Make standard maintenance operations (including VACUUM, ANALYZE, REINDEX,

and CLUSTER) execute as the table owner rather than the calling user, using
the same privilege-switching mechanism already used for SECURITY DEFINER
functions.  The purpose of this change is to ensure that user-defined
functions used in index definitions cannot acquire the privileges of a
superuser account that is performing routine maintenance.  While a function
used in an index is supposed to be IMMUTABLE and thus not able to do anything
very interesting, there are several easy ways around that restriction; and
even if we could plug them all, there would remain a risk of reading sensitive
information and broadcasting it through a covert channel such as CPU usage.

To prevent bypassing this security measure, execution of SET SESSION
AUTHORIZATION and SET ROLE is now forbidden within a SECURITY DEFINER context.

Thanks to Itagaki Takahiro for reporting this vulnerability.

Security: CVE-2007-6600

1 files changed, 17 insertions, 6 deletions

diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index e188f7297d5..91a0cc05b35 100644
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.80 2004/12/31 21:59:41 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.80.4.1 2008/01/03 21:25:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -110,6 +110,8 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
 				numrows;
 	double		totalrows;
 	HeapTuple  *rows;
+	AclId		save_userid;
+	bool		save_secdefcxt;
 
 	if (vacstmt->verbose)
 		elevel = INFO;
@@ -200,6 +202,13 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
 					RelationGetRelationName(onerel))));
 
 	/*
+	 * Switch to the table owner's userid, so that any index functions are
+	 * run as that user.
+	 */
+	GetUserIdAndContext(&save_userid, &save_secdefcxt);
+	SetUserIdAndContext(onerel->rd_rel->relowner, true);
+
+	/*
 	 * Determine which columns to analyze
 	 *
 	 * Note that system attributes are never analyzed.
@@ -309,11 +318,7 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
 	 * Quit if no analyzable columns
 	 */
 	if (attr_cnt <= 0 && !analyzableindex)
-	{
-		vac_close_indexes(nindexes, Irel, AccessShareLock);
-		relation_close(onerel, AccessShareLock);
-		return;
-	}
+		goto cleanup;
 
 	/*
 	 * Determine how many rows we need to sample, using the worst case
@@ -426,6 +431,9 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
 		}
 	}
 
+	/* We skip to here if there were no analyzable columns */
+cleanup:
+
 	/* Done with indexes */
 	vac_close_indexes(nindexes, Irel, NoLock);
 
@@ -435,6 +443,9 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
 	 * entries we made in pg_statistic.)
 	 */
 	relation_close(onerel, NoLock);
+
+	/* Restore userid */
+	SetUserIdAndContext(save_userid, save_secdefcxt);
 }
 
 /*