From 3af35f8d40bede09c4fe976050ff402dc346dbf2 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 3 Jan 2008 21:23:45 +0000
Subject: 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
---
 src/backend/commands/analyze.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

(limited to 'src/backend/commands/analyze.c')

diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index 95410258d34..233345c1c47 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 1.101 2006/11/05 22:42:08 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.101.2.1 2008/01/03 21:23:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -109,6 +109,8 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
 	double		totalrows,
 				totaldeadrows;
 	HeapTuple  *rows;
+	Oid			save_userid;
+	bool		save_secdefcxt;
 
 	if (vacstmt->verbose)
 		elevel = INFO;
@@ -195,6 +197,13 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
 					get_namespace_name(RelationGetNamespace(onerel)),
 					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
 	 *
@@ -319,9 +328,7 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
 								  onerel->rd_rel->relisshared,
 								  0, 0);
 
-		vac_close_indexes(nindexes, Irel, AccessShareLock);
-		relation_close(onerel, ShareUpdateExclusiveLock);
-		return;
+		goto cleanup;
 	}
 
 	/*
@@ -441,6 +448,9 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
 							  totalrows, totaldeadrows);
 	}
 
+	/* We skip to here if there were no analyzable columns */
+cleanup:
+
 	/* Done with indexes */
 	vac_close_indexes(nindexes, Irel, NoLock);
 
@@ -451,6 +461,9 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
 	 * expose us to concurrent-update failures in update_attstats.)
 	 */
 	relation_close(onerel, NoLock);
+
+	/* Restore userid */
+	SetUserIdAndContext(save_userid, save_secdefcxt);
 }
 
 /*
-- 
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