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[PATCH v28 07/11] Add DISTINCT support for IVM 721+ messages / 2 participants [nested] [flat]
* [PATCH v28 07/11] Add DISTINCT support for IVM @ 2023-05-31 10:08 Yugo Nagata <[email protected]> 0 siblings, 0 replies; 721+ messages in thread From: Yugo Nagata @ 2023-05-31 10:08 UTC (permalink / raw) When IMMV is created with DISTINCT, multiplicity of tuples is counted and stored in "__ivm_count__" column, which is a hidden column of IMMV. The value in __ivm_count__ is updated when IMMV is maintained incrementally. A tuple in IMMV can be removed if and only if the count becomes zero. --- src/backend/commands/createas.c | 141 ++++++++++++++++++++------ src/backend/commands/indexcmds.c | 40 ++++++++ src/backend/commands/matview.c | 148 ++++++++++++++++++++++++++-- src/backend/commands/tablecmds.c | 9 ++ src/backend/parser/parse_relation.c | 18 +++- src/backend/rewrite/rewriteDefine.c | 3 +- src/include/commands/createas.h | 2 + src/include/nodes/parsenodes.h | 1 + 8 files changed, 317 insertions(+), 45 deletions(-) diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c index 415f110516..076f35ee6b 100644 --- a/src/backend/commands/createas.c +++ b/src/backend/commands/createas.c @@ -53,6 +53,7 @@ #include "parser/parser.h" #include "parser/parsetree.h" #include "parser/parse_clause.h" +#include "parser/parse_func.h" #include "rewrite/rewriteHandler.h" #include "storage/smgr.h" #include "tcop/tcopprot.h" @@ -309,6 +310,9 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt, errhint("functions must be marked IMMUTABLE"))); check_ivm_restriction((Node *) query); + + /* For IMMV, we need to rewrite matview query */ + query = rewriteQueryForIMMV(query, into->colNames); } if (into->skipData) @@ -413,6 +417,49 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt, return address; } +/* + * rewriteQueryForIMMV -- rewrite view definition query for IMMV + * + * count(*) is added for counting distinct tuples in views. + */ +Query * +rewriteQueryForIMMV(Query *query, List *colNames) +{ + Query *rewritten; + + Node *node; + ParseState *pstate = make_parsestate(NULL); + FuncCall *fn; + + rewritten = copyObject(query); + pstate->p_expr_kind = EXPR_KIND_SELECT_TARGET; + + /* + * Convert DISTINCT to GROUP BY and add count(*) for counting distinct + * tuples in views. + */ + if (rewritten->distinctClause) + { + TargetEntry *tle; + + rewritten->groupClause = transformDistinctClause(NULL, &rewritten->targetList, rewritten->sortClause, false); + + fn = makeFuncCall(SystemFuncName("count"), NIL, COERCE_EXPLICIT_CALL, -1); + fn->agg_star = true; + + node = ParseFuncOrColumn(pstate, fn->funcname, NIL, NULL, fn, false, -1); + + tle = makeTargetEntry((Expr *) node, + list_length(rewritten->targetList) + 1, + pstrdup("__ivm_count__"), + false); + rewritten->targetList = lappend(rewritten->targetList, tle); + rewritten->hasAggs = true; + } + + return rewritten; +} + /* * GetIntoRelEFlags --- compute executor flags needed for CREATE TABLE AS * @@ -536,7 +583,8 @@ intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo) ColumnDef *col; char *colname; - if (lc) + /* Don't override hidden columns added for IVM */ + if (lc && !isIvmName(NameStr(attribute->attname))) { colname = strVal(lfirst(lc)); lc = lnext(into->colNames, lc); @@ -940,10 +988,6 @@ check_ivm_restriction_walker(Node *node, void *context) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("LIMIT/OFFSET clause is not supported on incrementally maintainable materialized view"))); - if (qry->distinctClause) - ereport(ERROR, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("DISTINCT is not supported on incrementally maintainable materialized view"))); if (qry->hasDistinctOn) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), @@ -1090,12 +1134,18 @@ CreateIndexOnIMMV(Query *query, Relation matviewRel) char idxname[NAMEDATALEN]; List *indexoidlist = RelationGetIndexList(matviewRel); ListCell *indexoidscan; - Bitmapset *key_attnos; snprintf(idxname, sizeof(idxname), "%s_index", RelationGetRelationName(matviewRel)); index = makeNode(IndexStmt); + /* + * We consider null values not distinct to make sure that views with DISTINCT + * or GROUP BY don't contain multiple NULL rows when NULL is inserted to + * a base table concurrently. + */ + index->nulls_not_distinct = true; + index->unique = true; index->primary = false; index->isconstraint = false; @@ -1122,41 +1172,68 @@ CreateIndexOnIMMV(Query *query, Relation matviewRel) index->concurrent = false; index->if_not_exists = false; - /* create index on the base tables' primary key columns */ - key_attnos = get_primary_key_attnos_from_query(query, &constraintList); - if (key_attnos) + if (query->distinctClause) { + /* create unique constraint on all columns */ foreach(lc, query->targetList) { TargetEntry *tle = (TargetEntry *) lfirst(lc); Form_pg_attribute attr = TupleDescAttr(matviewRel->rd_att, tle->resno - 1); - - if (bms_is_member(tle->resno - FirstLowInvalidHeapAttributeNumber, key_attnos)) - { - IndexElem *iparam; - - iparam = makeNode(IndexElem); - iparam->name = pstrdup(NameStr(attr->attname)); - iparam->expr = NULL; - iparam->indexcolname = NULL; - iparam->collation = NIL; - iparam->opclass = NIL; - iparam->opclassopts = NIL; - iparam->ordering = SORTBY_DEFAULT; - iparam->nulls_ordering = SORTBY_NULLS_DEFAULT; - index->indexParams = lappend(index->indexParams, iparam); - } + IndexElem *iparam; + + iparam = makeNode(IndexElem); + iparam->name = pstrdup(NameStr(attr->attname)); + iparam->expr = NULL; + iparam->indexcolname = NULL; + iparam->collation = NIL; + iparam->opclass = NIL; + iparam->opclassopts = NIL; + iparam->ordering = SORTBY_DEFAULT; + iparam->nulls_ordering = SORTBY_NULLS_DEFAULT; + index->indexParams = lappend(index->indexParams, iparam); } } else { - /* create no index, just notice that an appropriate index is necessary for efficient IVM */ - ereport(NOTICE, - (errmsg("could not create an index on materialized view \"%s\" automatically", - RelationGetRelationName(matviewRel)), - errdetail("This target list does not have all the primary key columns. "), - errhint("Create an index on the materialized view for efficient incremental maintenance."))); - return; + Bitmapset *key_attnos; + + /* create index on the base tables' primary key columns */ + key_attnos = get_primary_key_attnos_from_query(query, &constraintList); + if (key_attnos) + { + foreach(lc, query->targetList) + { + TargetEntry *tle = (TargetEntry *) lfirst(lc); + Form_pg_attribute attr = TupleDescAttr(matviewRel->rd_att, tle->resno - 1); + + if (bms_is_member(tle->resno - FirstLowInvalidHeapAttributeNumber, key_attnos)) + { + IndexElem *iparam; + + iparam = makeNode(IndexElem); + iparam->name = pstrdup(NameStr(attr->attname)); + iparam->expr = NULL; + iparam->indexcolname = NULL; + iparam->collation = NIL; + iparam->opclass = NIL; + iparam->opclassopts = NIL; + iparam->ordering = SORTBY_DEFAULT; + iparam->nulls_ordering = SORTBY_NULLS_DEFAULT; + index->indexParams = lappend(index->indexParams, iparam); + } + } + } + else + { + /* create no index, just notice that an appropriate index is necessary for efficient IVM */ + ereport(NOTICE, + (errmsg("could not create an index on materialized view \"%s\" automatically", + RelationGetRelationName(matviewRel)), + errdetail("This target list does not have all the primary key columns, " + "or this view does not contain DISTINCT clause."), + errhint("Create an index on the materialized view for efficient incremental maintenance."))); + return; + } } /* If we have a compatible index, we don't need to create another. */ diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c index a5168c9f09..480c3a00ed 100644 --- a/src/backend/commands/indexcmds.c +++ b/src/backend/commands/indexcmds.c @@ -39,6 +39,7 @@ #include "commands/dbcommands.h" #include "commands/defrem.h" #include "commands/event_trigger.h" +#include "commands/matview.h" #include "commands/progress.h" #include "commands/tablecmds.h" #include "commands/tablespace.h" @@ -1090,6 +1091,45 @@ DefineIndex(Oid relationId, safe_index = indexInfo->ii_Expressions == NIL && indexInfo->ii_Predicate == NIL; + /* + * We disallow unique indexes on IVM columns of IMMVs. + */ + if (RelationIsIVM(rel) && stmt->unique) + { + for (int i = 0; i < indexInfo->ii_NumIndexKeyAttrs; i++) + { + AttrNumber attno = indexInfo->ii_IndexAttrNumbers[i]; + if (attno > 0) + { + char *name = NameStr(TupleDescAttr(rel->rd_att, attno - 1)->attname); + if (name && isIvmName(name)) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("unique index creation on IVM columns is not supported"))); + } + } + + if (indexInfo->ii_Expressions) + { + Bitmapset *indexattrs = NULL; + int varno = -1; + + pull_varattnos((Node *) indexInfo->ii_Expressions, 1, &indexattrs); + + while ((varno = bms_next_member(indexattrs, varno)) >= 0) + { + int attno = varno + FirstLowInvalidHeapAttributeNumber; + char *name = NameStr(TupleDescAttr(rel->rd_att, attno - 1)->attname); + if (name && isIvmName(name)) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("unique index creation on IVM columns is not supported"))); + } + + } + } + + /* * Report index creation if appropriate (delay this till after most of the * error checks) diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c index fd9d0d99ae..6d8382180a 100644 --- a/src/backend/commands/matview.c +++ b/src/backend/commands/matview.c @@ -152,11 +152,15 @@ static Query *rewrite_query_for_postupdate_state(Query *query, MV_TriggerTable * static void apply_delta(Oid matviewOid, Tuplestorestate *old_tuplestores, Tuplestorestate *new_tuplestores, TupleDesc tupdesc_old, TupleDesc tupdesc_new, - Query *query); + Query *query, bool use_count, char *count_colname); static void apply_old_delta(const char *matviewname, const char *deltaname_old, List *keys); +static void apply_old_delta_with_count(const char *matviewname, const char *deltaname_old, + List *keys, const char *count_colname); static void apply_new_delta(const char *matviewname, const char *deltaname_new, StringInfo target_list); +static void apply_new_delta_with_count(const char *matviewname, const char* deltaname_new, + List *keys, StringInfo target_list, const char* count_colname); static char *get_matching_condition_string(List *keys); static void generate_equal(StringInfo querybuf, Oid opttype, const char *leftop, const char *rightop); @@ -271,6 +275,7 @@ ExecRefreshMatView(RefreshMatViewStmt *stmt, const char *queryString, Oid matviewOid; Relation matviewRel; Query *dataQuery; + Query *viewQuery; Oid tableSpace; Oid relowner; Oid OIDNewHeap; @@ -331,8 +336,13 @@ ExecRefreshMatView(RefreshMatViewStmt *stmt, const char *queryString, "CONCURRENTLY", "WITH NO DATA"))); - dataQuery = get_matview_query(matviewRel); + viewQuery = get_matview_query(matviewRel); + /* For IMMV, we need to rewrite matview query */ + if (!stmt->skipData && RelationIsIVM(matviewRel)) + dataQuery = rewriteQueryForIMMV(viewQuery,NIL); + else + dataQuery = viewQuery; /* * Check that there is a unique index with no WHERE clause on one or more @@ -512,8 +522,8 @@ ExecRefreshMatView(RefreshMatViewStmt *stmt, const char *queryString, if (!stmt->skipData && RelationIsIVM(matviewRel) && !oldPopulated) { - CreateIndexOnIMMV(dataQuery, matviewRel); - CreateIvmTriggersOnBaseTables(dataQuery, matviewOid); + CreateIndexOnIMMV(viewQuery, matviewRel); + CreateIvmTriggersOnBaseTables(viewQuery, matviewOid); } table_close(matviewRel, NoLock); @@ -1513,6 +1523,13 @@ IVM_immediate_maintenance(PG_FUNCTION_ARGS) int rte_index = lfirst_int(lc2); TupleDesc tupdesc_old; TupleDesc tupdesc_new; + bool use_count = false; + char *count_colname = NULL; + + count_colname = pstrdup("__ivm_count__"); + + if (query->distinctClause) + use_count = true; /* calculate delta tables */ calc_delta(table, rte_index, rewritten, dest_old, dest_new, @@ -1525,7 +1542,8 @@ IVM_immediate_maintenance(PG_FUNCTION_ARGS) { /* apply the delta tables to the materialized view */ apply_delta(matviewOid, old_tuplestore, new_tuplestore, - tupdesc_old, tupdesc_new, query); + tupdesc_old, tupdesc_new, query, use_count, + count_colname); } PG_CATCH(); { @@ -1998,7 +2016,7 @@ rewrite_query_for_postupdate_state(Query *query, MV_TriggerTable *table, int rte static void apply_delta(Oid matviewOid, Tuplestorestate *old_tuplestores, Tuplestorestate *new_tuplestores, TupleDesc tupdesc_old, TupleDesc tupdesc_new, - Query *query) + Query *query, bool use_count, char *count_colname) { StringInfoData querybuf; StringInfoData target_list_buf; @@ -2074,7 +2092,12 @@ apply_delta(Oid matviewOid, Tuplestorestate *old_tuplestores, Tuplestorestate *n if (rc != SPI_OK_REL_REGISTER) elog(ERROR, "SPI_register failed"); - apply_old_delta(matviewname, OLD_DELTA_ENRNAME, keys); + if (use_count) + /* apply old delta and get rows to be recalculated */ + apply_old_delta_with_count(matviewname, OLD_DELTA_ENRNAME, + keys, count_colname); + else + apply_old_delta(matviewname, OLD_DELTA_ENRNAME, keys); } /* For tuple insertion */ @@ -2096,7 +2119,11 @@ apply_delta(Oid matviewOid, Tuplestorestate *old_tuplestores, Tuplestorestate *n elog(ERROR, "SPI_register failed"); /* apply new delta */ - apply_new_delta(matviewname, NEW_DELTA_ENRNAME, &target_list_buf); + if (use_count) + apply_new_delta_with_count(matviewname, NEW_DELTA_ENRNAME, + keys, &target_list_buf, count_colname); + else + apply_new_delta(matviewname, NEW_DELTA_ENRNAME, &target_list_buf); } /* We're done maintaining the materialized view. */ @@ -2109,6 +2136,51 @@ apply_delta(Oid matviewOid, Tuplestorestate *old_tuplestores, Tuplestorestate *n elog(ERROR, "SPI_finish failed"); } +/* + * apply_old_delta_with_count + * + * Execute a query for applying a delta table given by deltname_old + * which contains tuples to be deleted from to a materialized view given by + * matviewname. This is used when counting is required, that is, the view + * has aggregate or distinct. + */ +static void +apply_old_delta_with_count(const char *matviewname, const char *deltaname_old, + List *keys, const char *count_colname) +{ + StringInfoData querybuf; + char *match_cond; + + /* build WHERE condition for searching tuples to be deleted */ + match_cond = get_matching_condition_string(keys); + + /* Search for matching tuples from the view and update or delete if found. */ + initStringInfo(&querybuf); + appendStringInfo(&querybuf, + "WITH t AS (" /* collecting tid of target tuples in the view */ + "SELECT diff.%s, " /* count column */ + "(diff.%s OPERATOR(pg_catalog.=) mv.%s) AS for_dlt, " + "mv.ctid " + "FROM %s AS mv, %s AS diff " + "WHERE %s" /* tuple matching condition */ + "), updt AS (" /* update a tuple if this is not to be deleted */ + "UPDATE %s AS mv SET %s = mv.%s OPERATOR(pg_catalog.-) t.%s " + "FROM t WHERE mv.ctid OPERATOR(pg_catalog.=) t.ctid AND NOT for_dlt " + ")" + /* delete a tuple if this is to be deleted */ + "DELETE FROM %s AS mv USING t " + "WHERE mv.ctid OPERATOR(pg_catalog.=) t.ctid AND for_dlt", + count_colname, + count_colname, count_colname, + matviewname, deltaname_old, + match_cond, + matviewname, count_colname, count_colname, count_colname, + matviewname); + + if (SPI_exec(querybuf.data, 0) != SPI_OK_DELETE) + elog(ERROR, "SPI_exec failed: %s", querybuf.data); +} + /* * apply_old_delta * @@ -2158,6 +2230,66 @@ apply_old_delta(const char *matviewname, const char *deltaname_old, elog(ERROR, "SPI_exec failed: %s", querybuf.data); } +/* + * apply_new_delta_with_count + * + * Execute a query for applying a delta table given by deltname_new + * which contains tuples to be inserted into a materialized view given by + * matviewname. This is used when counting is required, that is, the view + * has aggregate or distinct. Also, when a table in EXISTS sub queries + * is modified. + */ +static void +apply_new_delta_with_count(const char *matviewname, const char* deltaname_new, + List *keys, StringInfo target_list, const char* count_colname) +{ + StringInfoData querybuf; + StringInfoData returning_keys; + ListCell *lc; + char *match_cond = ""; + + /* build WHERE condition for searching tuples to be updated */ + match_cond = get_matching_condition_string(keys); + + /* build string of keys list */ + initStringInfo(&returning_keys); + if (keys) + { + foreach (lc, keys) + { + Form_pg_attribute attr = (Form_pg_attribute) lfirst(lc); + char *resname = NameStr(attr->attname); + appendStringInfo(&returning_keys, "%s", quote_qualified_identifier("mv", resname)); + if (lnext(keys, lc)) + appendStringInfo(&returning_keys, ", "); + } + } + else + appendStringInfo(&returning_keys, "NULL"); + + /* Search for matching tuples from the view and update if found or insert if not. */ + initStringInfo(&querybuf); + appendStringInfo(&querybuf, + "WITH updt AS (" /* update a tuple if this exists in the view */ + "UPDATE %s AS mv SET %s = mv.%s OPERATOR(pg_catalog.+) diff.%s " + "FROM %s AS diff " + "WHERE %s " /* tuple matching condition */ + "RETURNING %s" /* returning keys of updated tuples */ + ") INSERT INTO %s (%s)" /* insert a new tuple if this doesn't existw */ + "SELECT %s FROM %s AS diff " + "WHERE NOT EXISTS (SELECT 1 FROM updt AS mv WHERE %s);", + matviewname, count_colname, count_colname, count_colname, + deltaname_new, + match_cond, + returning_keys.data, + matviewname, target_list->data, + target_list->data, deltaname_new, + match_cond); + + if (SPI_exec(querybuf.data, 0) != SPI_OK_INSERT) + elog(ERROR, "SPI_exec failed: %s", querybuf.data); +} + /* * apply_new_delta * diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 4d49d70c33..25ff2a23db 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -53,6 +53,7 @@ #include "commands/cluster.h" #include "commands/comment.h" #include "commands/defrem.h" +#include "commands/matview.h" #include "commands/event_trigger.h" #include "commands/policy.h" #include "commands/sequence.h" @@ -3548,6 +3549,14 @@ renameatt_internal(Oid myrelid, targetrelation = relation_open(myrelid, AccessExclusiveLock); renameatt_check(myrelid, RelationGetForm(targetrelation), recursing); + /* + * Don't rename IVM columns. + */ + if (RelationIsIVM(targetrelation) && isIvmName(oldattname)) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("IVM column can not be renamed"))); + /* * if the 'recurse' flag is set then we are supposed to rename this * attribute in all classes that inherit from 'relname' (as well as in diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c index 41d60494b9..f516ac91e2 100644 --- a/src/backend/parser/parse_relation.c +++ b/src/backend/parser/parse_relation.c @@ -36,6 +36,7 @@ #include "utils/rel.h" #include "utils/syscache.h" #include "utils/varlena.h" +#include "commands/matview.h" /* @@ -97,7 +98,7 @@ static void expandTupleDesc(TupleDesc tupdesc, Alias *eref, int count, int offset, int rtindex, int sublevels_up, int location, bool include_dropped, - List **colnames, List **colvars); + List **colnames, List **colvars, bool is_ivm); static int specialAttNum(const char *attname); static bool rte_visible_if_lateral(ParseState *pstate, RangeTblEntry *rte); static bool rte_visible_if_qualified(ParseState *pstate, RangeTblEntry *rte); @@ -1501,6 +1502,7 @@ addRangeTableEntry(ParseState *pstate, rte->relid = RelationGetRelid(rel); rte->relkind = rel->rd_rel->relkind; rte->rellockmode = lockmode; + rte->relisivm = rel->rd_rel->relisivm; /* * Build the list of effective column names using user-supplied aliases @@ -1586,6 +1588,7 @@ addRangeTableEntryForRelation(ParseState *pstate, rte->relid = RelationGetRelid(rel); rte->relkind = rel->rd_rel->relkind; rte->rellockmode = lockmode; + rte->relisivm = rel->rd_rel->relisivm; /* * Build the list of effective column names using user-supplied aliases @@ -2757,7 +2760,7 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up, expandTupleDesc(tupdesc, rte->eref, rtfunc->funccolcount, atts_done, rtindex, sublevels_up, location, - include_dropped, colnames, colvars); + include_dropped, colnames, colvars, false); } else if (functypclass == TYPEFUNC_SCALAR) { @@ -3025,7 +3028,7 @@ expandRelation(Oid relid, Alias *eref, int rtindex, int sublevels_up, expandTupleDesc(rel->rd_att, eref, rel->rd_att->natts, 0, rtindex, sublevels_up, location, include_dropped, - colnames, colvars); + colnames, colvars, RelationIsIVM(rel)); relation_close(rel, AccessShareLock); } @@ -3042,7 +3045,7 @@ static void expandTupleDesc(TupleDesc tupdesc, Alias *eref, int count, int offset, int rtindex, int sublevels_up, int location, bool include_dropped, - List **colnames, List **colvars) + List **colnames, List **colvars, bool is_ivm) { ListCell *aliascell; int varattno; @@ -3055,6 +3058,9 @@ expandTupleDesc(TupleDesc tupdesc, Alias *eref, int count, int offset, { Form_pg_attribute attr = TupleDescAttr(tupdesc, varattno); + if (is_ivm && isIvmName(NameStr(attr->attname)) && !MatViewIncrementalMaintenanceIsEnabled()) + continue; + if (attr->attisdropped) { if (include_dropped) @@ -3217,6 +3223,10 @@ expandNSItemAttrs(ParseState *pstate, ParseNamespaceItem *nsitem, Var *varnode = (Var *) lfirst(var); TargetEntry *te; + /* if transform * into columnlist with IMMV, remove IVM columns */ + if (rte->relisivm && isIvmName(label) && !MatViewIncrementalMaintenanceIsEnabled()) + continue; + te = makeTargetEntry((Expr *) varnode, (AttrNumber) pstate->p_next_resno++, label, diff --git a/src/backend/rewrite/rewriteDefine.c b/src/backend/rewrite/rewriteDefine.c index e36fc72e1e..f6dc7ba202 100644 --- a/src/backend/rewrite/rewriteDefine.c +++ b/src/backend/rewrite/rewriteDefine.c @@ -621,7 +621,8 @@ checkRuleResultList(List *targetList, TupleDesc resultDesc, bool isSelect, attr->atttypmod)))); } - if (i != resultDesc->natts) + /* No check for materialized views since this could have special columns for IVM */ + if ((!isSelect || requireColumnNameMatch) && i != resultDesc->natts) ereport(ERROR, (errcode(ERRCODE_INVALID_OBJECT_DEFINITION), isSelect ? diff --git a/src/include/commands/createas.h b/src/include/commands/createas.h index 09a64fa2e5..76a7873ebf 100644 --- a/src/include/commands/createas.h +++ b/src/include/commands/createas.h @@ -29,6 +29,8 @@ extern ObjectAddress ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *st extern void CreateIvmTriggersOnBaseTables(Query *qry, Oid matviewOid); extern void CreateIndexOnIMMV(Query *query, Relation matviewRel); +extern Query *rewriteQueryForIMMV(Query *query, List *colNames); + extern int GetIntoRelEFlags(IntoClause *intoClause); extern DestReceiver *CreateIntoRelDestReceiver(IntoClause *intoClause); diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h index 0ca298f5a1..43c4ed49f1 100644 --- a/src/include/nodes/parsenodes.h +++ b/src/include/nodes/parsenodes.h @@ -1074,6 +1074,7 @@ typedef struct RangeTblEntry int rellockmode; /* lock level that query requires on the rel */ struct TableSampleClause *tablesample; /* sampling info, or NULL */ Index perminfoindex; + bool relisivm; /* * Fields valid for a subquery RTE (else NULL): -- 2.25.1 --Multipart=_Thu__1_Jun_2023_23_59_09_+0900_/G5+8nG46.f1T42K Content-Type: text/x-diff; name="v28-0008-Add-aggregates-support-in-IVM.patch" Content-Disposition: attachment; filename="v28-0008-Add-aggregates-support-in-IVM.patch" Content-Transfer-Encoding: quoted-printable ^ permalink raw reply [nested|flat] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ 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; 721+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef 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] 721+ messages in thread
end of thread, other threads:[~2026-07-06 08:28 UTC | newest] Thread overview: 721+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2023-05-31 10:08 [PATCH v28 07/11] Add DISTINCT support for IVM Yugo Nagata <[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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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]>
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