postgres.git / summary / log / commit / refs

commit    a316a3bc6d3f57e3fe0d287d11eb4f114388b1b6
Author:   Alvaro Herrera <alvherre@alvh.no-ip.org>
Date:     Mon Feb 20 15:00:42 2023 +0000
First released in: 16.0

    Correctly set userid of subquery relations' child rels
    
    The RelOptInfo->userid field (the user ID to check permissions as) of an
    "otherrel" relation was being copied from its parent relation, which is
    correct in most cases but wrong when the parent is a subquery.  In that
    case, using the value from the RTEPermissionInfo of the child itself is
    the appropriate thing to do.
    
    Coming up with a test case where user-visible behavior changes proves
    hard enough, so we don't add one here.
    
    Bug introduced by a61b1f74823c, discovered by Amit while reviewing
    nearby code.
    
    Author: Amit Langote <amitlangote09@gmail.com>
    Discussion: https://postgr.es/m/CA+HiwqE0WY_AhLnGtTsY7eYebG212XWbM-D8gr2A_ToOHyCywQ@mail.gmail.com


 src/backend/optimizer/util/relnode.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c
index a70a16238a8..d29a25f8aa6 100644
--- a/src/backend/optimizer/util/relnode.c
+++ b/src/backend/optimizer/util/relnode.c
@@ -233,12 +233,22 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptInfo *parent)
 	rel->serverid = InvalidOid;
 	if (rte->rtekind == RTE_RELATION)
 	{
+		Assert(parent == NULL ||
+			   parent->rtekind == RTE_RELATION ||
+			   parent->rtekind == RTE_SUBQUERY);
+
 		/*
-		 * Get the userid from the relation's RTEPermissionInfo, though only
-		 * the tables mentioned in query are assigned RTEPermissionInfos.
-		 * Child relations (otherrels) simply use the parent's value.
+		 * For any RELATION rte, we need a userid with which to check
+		 * permission access. Baserels simply use their own
+		 * RTEPermissionInfo's checkAsUser.
+		 *
+		 * For otherrels normally there's no RTEPermissionInfo, so we use the
+		 * parent's, which normally has one. The exceptional case is that the
+		 * parent is a subquery, in which case the otherrel will have its own.
 		 */
-		if (parent == NULL)
+		if (rel->reloptkind == RELOPT_BASEREL ||
+			(rel->reloptkind == RELOPT_OTHER_MEMBER_REL &&
+			 parent->rtekind == RTE_SUBQUERY))
 		{
 			RTEPermissionInfo *perminfo;
 


[parent: 94cad7a3e604]