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, 66 insertions, 4 deletions

diff --git a/contrib/pageinspect/btreefuncs.c b/contrib/pageinspect/btreefuncs.c
index ab80b54500..85935b9990 100644
--- a/contrib/pageinspect/btreefuncs.c
+++ b/contrib/pageinspect/btreefuncs.c
@@ -1,5 +1,5 @@
 /*
- * $PostgreSQL: pgsql/contrib/pageinspect/btreefuncs.c,v 1.8 2008/05/17 01:28:19 adunstan Exp $ 
+ * $PostgreSQL: pgsql/contrib/pageinspect/btreefuncs.c,v 1.9 2009/03/31 22:54:31 tgl Exp $ 
  *
  *
  * btreefuncs.c
@@ -190,6 +190,16 @@ 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 (RELATION_IS_OTHER_TEMP(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");
 
@@ -298,6 +308,16 @@ 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 (RELATION_IS_OTHER_TEMP(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");
 
@@ -437,6 +457,16 @@ 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 (RELATION_IS_OTHER_TEMP(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 607f55eef0..91b6a1915f 100644
--- a/contrib/pageinspect/rawpage.c
+++ b/contrib/pageinspect/rawpage.c
@@ -8,7 +8,7 @@
  * Copyright (c) 2007-2009, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/contrib/pageinspect/rawpage.c,v 1.10 2009/01/01 17:23:32 momjian Exp $
+ *	  $PostgreSQL: pgsql/contrib/pageinspect/rawpage.c,v 1.11 2009/03/31 22:54:31 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -74,6 +74,16 @@ 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 (RELATION_IS_OTHER_TEMP(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 dfb162d5e4..b00ae5b766 100644
--- a/contrib/pgstattuple/pgstatindex.c
+++ b/contrib/pgstattuple/pgstatindex.c
@@ -1,5 +1,5 @@
 /*
- * $PostgreSQL: pgsql/contrib/pgstattuple/pgstatindex.c,v 1.11 2008/05/17 01:28:22 adunstan Exp $ 
+ * $PostgreSQL: pgsql/contrib/pgstattuple/pgstatindex.c,v 1.12 2009/03/31 22:54:31 tgl Exp $ 
  *
  *
  * pgstatindex
@@ -108,6 +108,16 @@ 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 (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions")));
+
+	/*
 	 * Read metapage
 	 */
 	{
@@ -262,6 +272,8 @@ 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 f4c046ca8c..c2c5d11e5a 100644
--- a/contrib/pgstattuple/pgstattuple.c
+++ b/contrib/pgstattuple/pgstattuple.c
@@ -1,5 +1,5 @@
 /*
- * $PostgreSQL: pgsql/contrib/pgstattuple/pgstattuple.c,v 1.36 2008/06/19 00:46:03 alvherre Exp $
+ * $PostgreSQL: pgsql/contrib/pgstattuple/pgstattuple.c,v 1.37 2009/03/31 22:54:31 tgl Exp $
  *
  * Copyright (c) 2001,2002	Tatsuo Ishii
  *
@@ -199,6 +199,16 @@ 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 (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions")));
+
 	switch (rel->rd_rel->relkind)
 	{
 		case RELKIND_RELATION: