Fix contrib/pgstattuple and contrib/pageinspect to prevent attempts to read

temporary tables of other sessions; that is unsafe because of the way our
buffer management works.  Per report from Stuart Bishop.
This is redundant with the bufmgr.c checks in HEAD, but not at all redundant
in the back branches.

4 files changed, 64 insertions, 2 deletions

diff --git a/contrib/pageinspect/btreefuncs.c b/contrib/pageinspect/btreefuncs.c
index ce8b97e46ba..c50c5da0bdb 100644
--- a/contrib/pageinspect/btreefuncs.c
+++ b/contrib/pageinspect/btreefuncs.c
@@ -186,6 +186,16 @@ bt_page_stats(PG_FUNCTION_ARGS)
 		elog(ERROR, "relation \"%s\" is not a btree index",
 			 RelationGetRelationName(rel));
 
+	/*
+	 * Reject attempts to read non-local temporary relations; we would
+	 * be likely to get wrong data since we have no visibility into the
+	 * owning session's local buffers.
+	 */
+	if (isOtherTempNamespace(RelationGetNamespace(rel)))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions")));
+
 	if (blkno == 0)
 		elog(ERROR, "block 0 is a meta page");
 
@@ -294,6 +304,16 @@ bt_page_items(PG_FUNCTION_ARGS)
 			elog(ERROR, "relation \"%s\" is not a btree index",
 				 RelationGetRelationName(rel));
 
+		/*
+		 * Reject attempts to read non-local temporary relations; we would
+		 * be likely to get wrong data since we have no visibility into the
+		 * owning session's local buffers.
+		 */
+		if (isOtherTempNamespace(RelationGetNamespace(rel)))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("cannot access temporary tables of other sessions")));
+
 		if (blkno == 0)
 			elog(ERROR, "block 0 is a meta page");
 
@@ -433,6 +453,16 @@ bt_metap(PG_FUNCTION_ARGS)
 		elog(ERROR, "relation \"%s\" is not a btree index",
 			 RelationGetRelationName(rel));
 
+	/*
+	 * Reject attempts to read non-local temporary relations; we would
+	 * be likely to get wrong data since we have no visibility into the
+	 * owning session's local buffers.
+	 */
+	if (isOtherTempNamespace(RelationGetNamespace(rel)))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions")));
+
 	buffer = ReadBuffer(rel, 0);
 	page = BufferGetPage(buffer);
 	metad = BTPageGetMeta(page);
diff --git a/contrib/pageinspect/rawpage.c b/contrib/pageinspect/rawpage.c
index 230d27133b8..75ab6fbfa32 100644
--- a/contrib/pageinspect/rawpage.c
+++ b/contrib/pageinspect/rawpage.c
@@ -8,7 +8,7 @@
  * Copyright (c) 2007-2008, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/contrib/pageinspect/rawpage.c,v 1.4 2008/01/01 20:31:21 tgl Exp $
+ *	  $PostgreSQL: pgsql/contrib/pageinspect/rawpage.c,v 1.4.2.1 2009/03/31 22:54:52 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -68,6 +68,16 @@ get_raw_page(PG_FUNCTION_ARGS)
 				 errmsg("cannot get raw page from composite type \"%s\"",
 						RelationGetRelationName(rel))));
 
+	/*
+	 * Reject attempts to read non-local temporary relations; we would
+	 * be likely to get wrong data since we have no visibility into the
+	 * owning session's local buffers.
+	 */
+	if (isOtherTempNamespace(RelationGetNamespace(rel)))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions")));
+
 	if (blkno >= RelationGetNumberOfBlocks(rel))
 		elog(ERROR, "block number %u is out of range for relation \"%s\"",
 			 blkno, RelationGetRelationName(rel));
diff --git a/contrib/pgstattuple/pgstatindex.c b/contrib/pgstattuple/pgstatindex.c
index 3cd31478956..f766739d744 100644
--- a/contrib/pgstattuple/pgstatindex.c
+++ b/contrib/pgstattuple/pgstatindex.c
@@ -104,6 +104,16 @@ pgstatindex(PG_FUNCTION_ARGS)
 			 RelationGetRelationName(rel));
 
 	/*
+	 * Reject attempts to read non-local temporary relations; we would
+	 * be likely to get wrong data since we have no visibility into the
+	 * owning session's local buffers.
+	 */
+	if (isOtherTempNamespace(RelationGetNamespace(rel)))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions")));
+
+	/*
 	 * Read metapage
 	 */
 	{
@@ -261,6 +271,8 @@ pg_relpages(PG_FUNCTION_ARGS)
 	relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
 	rel = relation_openrv(relrv, AccessShareLock);
 
+	/* note: this will work OK on non-local temp tables */
+
 	relpages = RelationGetNumberOfBlocks(rel);
 
 	relation_close(rel, AccessShareLock);
diff --git a/contrib/pgstattuple/pgstattuple.c b/contrib/pgstattuple/pgstattuple.c
index d252e23847d..989911fdd88 100644
--- a/contrib/pgstattuple/pgstattuple.c
+++ b/contrib/pgstattuple/pgstattuple.c
@@ -1,5 +1,5 @@
 /*
- * $PostgreSQL: pgsql/contrib/pgstattuple/pgstattuple.c,v 1.32 2008/01/14 02:53:31 tgl Exp $
+ * $PostgreSQL: pgsql/contrib/pgstattuple/pgstattuple.c,v 1.32.2.1 2009/03/31 22:54:52 tgl Exp $
  *
  * Copyright (c) 2001,2002	Tatsuo Ishii
  *
@@ -196,6 +196,16 @@ pgstat_relation(Relation rel, FunctionCallInfo fcinfo)
 {
 	const char *err;
 
+	/*
+	 * Reject attempts to read non-local temporary relations; we would
+	 * be likely to get wrong data since we have no visibility into the
+	 * owning session's local buffers.
+	 */
+	if (isOtherTempNamespace(RelationGetNamespace(rel)))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions")));
+
 	switch (rel->rd_rel->relkind)
 	{
 		case RELKIND_RELATION: