Avoid repeated name lookups during table and index DDL.

If the name lookups come to different conclusions due to concurrent
activity, we might perform some parts of the DDL on a different table
than other parts.  At least in the case of CREATE INDEX, this can be
used to cause the permissions checks to be performed against a
different table than the index creation, allowing for a privilege
escalation attack.

This changes the calling convention for DefineIndex, CreateTrigger,
transformIndexStmt, transformAlterTableStmt, CheckIndexCompatible
(in 9.2 and newer), and AlterTable (in 9.1 and older).  In addition,
CheckRelationOwnership is removed in 9.2 and newer and the calling
convention is changed in older branches.  A field has also been added
to the Constraint node (FkConstraint in 8.4).  Third-party code calling
these functions or using the Constraint node will require updating.

Report by Andres Freund.  Patch by Robert Haas and Andres Freund,
reviewed by Tom Lane.

Security: CVE-2014-0062

1 files changed, 100 insertions, 37 deletions

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 08b037e501f..fe0c0aca291 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -296,7 +296,8 @@ static void validateCheckConstraint(Relation rel, HeapTuple constrtup);
 static void validateForeignKeyConstraint(char *conname,
 							 Relation rel, Relation pkrel,
 							 Oid pkindOid, Oid constraintOid);
-static void createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
+static void createForeignKeyTriggers(Relation rel, Oid refRelOid,
+						 Constraint *fkconstraint,
 						 Oid constraintOid, Oid indexOid);
 static void ATController(Relation rel, List *cmds, bool recurse, LOCKMODE lockmode);
 static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
@@ -373,8 +374,9 @@ static void ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 static void ATExecAlterColumnGenericOptions(Relation rel, const char *colName,
 								List *options, LOCKMODE lockmode);
 static void ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode);
-static void ATPostAlterTypeParse(Oid oldId, char *cmd,
-					 List **wqueue, LOCKMODE lockmode, bool rewrite);
+static void ATPostAlterTypeParse(Oid oldId, Oid oldRelId, Oid refRelId,
+					 char *cmd, List **wqueue, LOCKMODE lockmode,
+					 bool rewrite);
 static void TryReuseIndex(Oid oldId, IndexStmt *stmt);
 static void TryReuseForeignKey(Oid oldId, Constraint *con);
 static void change_owner_fix_column_acls(Oid relationOid,
@@ -5539,7 +5541,8 @@ ATExecAddIndex(AlteredTableInfo *tab, Relation rel,
 
 	/* The IndexStmt has already been through transformIndexStmt */
 
-	new_index = DefineIndex(stmt,
+	new_index = DefineIndex(RelationGetRelid(rel),
+							stmt,
 							InvalidOid, /* no predefined OID */
 							true,		/* is_alter_table */
 							check_rights,
@@ -5863,7 +5866,10 @@ ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
 	 * table; trying to start with a lesser lock will just create a risk of
 	 * deadlock.)
 	 */
-	pkrel = heap_openrv(fkconstraint->pktable, AccessExclusiveLock);
+	if (OidIsValid(fkconstraint->old_pktable_oid))
+		pkrel = heap_open(fkconstraint->old_pktable_oid, AccessExclusiveLock);
+	else
+		pkrel = heap_openrv(fkconstraint->pktable, AccessExclusiveLock);
 
 	/*
 	 * Validity checks (permission checks wait till we have the column
@@ -6202,7 +6208,8 @@ ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
 	/*
 	 * Create the triggers that will enforce the constraint.
 	 */
-	createForeignKeyTriggers(rel, fkconstraint, constrOid, indexOid);
+	createForeignKeyTriggers(rel, RelationGetRelid(pkrel), fkconstraint,
+							 constrOid, indexOid);
 
 	/*
 	 * Tell Phase 3 to check that the constraint is satisfied by existing
@@ -7012,7 +7019,7 @@ validateForeignKeyConstraint(char *conname,
 }
 
 static void
-CreateFKCheckTrigger(RangeVar *myRel, Constraint *fkconstraint,
+CreateFKCheckTrigger(Oid myRelOid, Oid refRelOid, Constraint *fkconstraint,
 					 Oid constraintOid, Oid indexOid, bool on_insert)
 {
 	CreateTrigStmt *fk_trigger;
@@ -7028,7 +7035,7 @@ CreateFKCheckTrigger(RangeVar *myRel, Constraint *fkconstraint,
 	 */
 	fk_trigger = makeNode(CreateTrigStmt);
 	fk_trigger->trigname = "RI_ConstraintTrigger_c";
-	fk_trigger->relation = myRel;
+	fk_trigger->relation = NULL;
 	fk_trigger->row = true;
 	fk_trigger->timing = TRIGGER_TYPE_AFTER;
 
@@ -7049,10 +7056,11 @@ CreateFKCheckTrigger(RangeVar *myRel, Constraint *fkconstraint,
 	fk_trigger->isconstraint = true;
 	fk_trigger->deferrable = fkconstraint->deferrable;
 	fk_trigger->initdeferred = fkconstraint->initdeferred;
-	fk_trigger->constrrel = fkconstraint->pktable;
+	fk_trigger->constrrel = NULL;
 	fk_trigger->args = NIL;
 
-	(void) CreateTrigger(fk_trigger, NULL, constraintOid, indexOid, true);
+	(void) CreateTrigger(fk_trigger, NULL, myRelOid, refRelOid, constraintOid,
+						 indexOid, true);
 
 	/* Make changes-so-far visible */
 	CommandCounterIncrement();
@@ -7062,18 +7070,13 @@ CreateFKCheckTrigger(RangeVar *myRel, Constraint *fkconstraint,
  * Create the triggers that implement an FK constraint.
  */
 static void
-createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
+createForeignKeyTriggers(Relation rel, Oid refRelOid, Constraint *fkconstraint,
 						 Oid constraintOid, Oid indexOid)
 {
-	RangeVar   *myRel;
+	Oid			myRelOid;
 	CreateTrigStmt *fk_trigger;
 
-	/*
-	 * Reconstruct a RangeVar for my relation (not passed in, unfortunately).
-	 */
-	myRel = makeRangeVar(get_namespace_name(RelationGetNamespace(rel)),
-						 pstrdup(RelationGetRelationName(rel)),
-						 -1);
+	myRelOid = RelationGetRelid(rel);
 
 	/* Make changes-so-far visible */
 	CommandCounterIncrement();
@@ -7084,14 +7087,14 @@ createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
 	 */
 	fk_trigger = makeNode(CreateTrigStmt);
 	fk_trigger->trigname = "RI_ConstraintTrigger_a";
-	fk_trigger->relation = fkconstraint->pktable;
+	fk_trigger->relation = NULL;
 	fk_trigger->row = true;
 	fk_trigger->timing = TRIGGER_TYPE_AFTER;
 	fk_trigger->events = TRIGGER_TYPE_DELETE;
 	fk_trigger->columns = NIL;
 	fk_trigger->whenClause = NULL;
 	fk_trigger->isconstraint = true;
-	fk_trigger->constrrel = myRel;
+	fk_trigger->constrrel = NULL;
 	switch (fkconstraint->fk_del_action)
 	{
 		case FKCONSTR_ACTION_NOACTION:
@@ -7126,7 +7129,8 @@ createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
 	}
 	fk_trigger->args = NIL;
 
-	(void) CreateTrigger(fk_trigger, NULL, constraintOid, indexOid, true);
+	(void) CreateTrigger(fk_trigger, NULL, refRelOid, myRelOid, constraintOid,
+						 indexOid, true);
 
 	/* Make changes-so-far visible */
 	CommandCounterIncrement();
@@ -7137,14 +7141,14 @@ createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
 	 */
 	fk_trigger = makeNode(CreateTrigStmt);
 	fk_trigger->trigname = "RI_ConstraintTrigger_a";
-	fk_trigger->relation = fkconstraint->pktable;
+	fk_trigger->relation = NULL;
 	fk_trigger->row = true;
 	fk_trigger->timing = TRIGGER_TYPE_AFTER;
 	fk_trigger->events = TRIGGER_TYPE_UPDATE;
 	fk_trigger->columns = NIL;
 	fk_trigger->whenClause = NULL;
 	fk_trigger->isconstraint = true;
-	fk_trigger->constrrel = myRel;
+	fk_trigger->constrrel = NULL;
 	switch (fkconstraint->fk_upd_action)
 	{
 		case FKCONSTR_ACTION_NOACTION:
@@ -7179,7 +7183,8 @@ createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
 	}
 	fk_trigger->args = NIL;
 
-	(void) CreateTrigger(fk_trigger, NULL, constraintOid, indexOid, true);
+	(void) CreateTrigger(fk_trigger, NULL, refRelOid, myRelOid, constraintOid,
+						 indexOid, true);
 
 	/* Make changes-so-far visible */
 	CommandCounterIncrement();
@@ -7188,8 +7193,10 @@ createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
 	 * Build and execute CREATE CONSTRAINT TRIGGER statements for the CHECK
 	 * action for both INSERTs and UPDATEs on the referencing table.
 	 */
-	CreateFKCheckTrigger(myRel, fkconstraint, constraintOid, indexOid, true);
-	CreateFKCheckTrigger(myRel, fkconstraint, constraintOid, indexOid, false);
+	CreateFKCheckTrigger(myRelOid, refRelOid, fkconstraint, constraintOid,
+						 indexOid, true);
+	CreateFKCheckTrigger(myRelOid, refRelOid, fkconstraint, constraintOid,
+						 indexOid, false);
 }
 
 /*
@@ -8093,15 +8100,36 @@ ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode)
 	 * lock on the table the constraint is attached to, and we need to get
 	 * that before dropping.  It's safe because the parser won't actually look
 	 * at the catalogs to detect the existing entry.
+	 *
+	 * We can't rely on the output of deparsing to tell us which relation
+	 * to operate on, because concurrent activity might have made the name
+	 * resolve differently.  Instead, we've got to use the OID of the
+	 * constraint or index we're processing to figure out which relation
+	 * to operate on.
 	 */
 	forboth(oid_item, tab->changedConstraintOids,
 			def_item, tab->changedConstraintDefs)
-		ATPostAlterTypeParse(lfirst_oid(oid_item), (char *) lfirst(def_item),
+	{
+		Oid		oldId = lfirst_oid(oid_item);
+		Oid		relid;
+		Oid		confrelid;
+
+		get_constraint_relation_oids(oldId, &relid, &confrelid);
+		ATPostAlterTypeParse(oldId, relid, confrelid,
+							 (char *) lfirst(def_item),
 							 wqueue, lockmode, tab->rewrite);
+	}
 	forboth(oid_item, tab->changedIndexOids,
 			def_item, tab->changedIndexDefs)
-		ATPostAlterTypeParse(lfirst_oid(oid_item), (char *) lfirst(def_item),
+	{
+		Oid		oldId = lfirst_oid(oid_item);
+		Oid		relid;
+
+		relid = IndexGetRelation(oldId, false);
+		ATPostAlterTypeParse(oldId, relid, InvalidOid,
+							 (char *) lfirst(def_item),
 							 wqueue, lockmode, tab->rewrite);
+	}
 
 	/*
 	 * Now we can drop the existing constraints and indexes --- constraints
@@ -8134,12 +8162,13 @@ ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode)
 }
 
 static void
-ATPostAlterTypeParse(Oid oldId, char *cmd,
+ATPostAlterTypeParse(Oid oldId, Oid oldRelId, Oid refRelId, char *cmd,
 					 List **wqueue, LOCKMODE lockmode, bool rewrite)
 {
 	List	   *raw_parsetree_list;
 	List	   *querytree_list;
 	ListCell   *list_item;
+	Relation	rel;
 
 	/*
 	 * We expect that we will get only ALTER TABLE and CREATE INDEX
@@ -8155,16 +8184,21 @@ ATPostAlterTypeParse(Oid oldId, char *cmd,
 
 		if (IsA(stmt, IndexStmt))
 			querytree_list = lappend(querytree_list,
-									 transformIndexStmt((IndexStmt *) stmt,
+									 transformIndexStmt(oldRelId,
+														(IndexStmt *) stmt,
 														cmd));
 		else if (IsA(stmt, AlterTableStmt))
 			querytree_list = list_concat(querytree_list,
-							 transformAlterTableStmt((AlterTableStmt *) stmt,
+							 transformAlterTableStmt(oldRelId,
+													 (AlterTableStmt *) stmt,
 													 cmd));
 		else
 			querytree_list = lappend(querytree_list, stmt);
 	}
 
+	/* Caller should already have acquired whatever lock we need. */
+	rel = relation_open(oldRelId, NoLock);
+
 	/*
 	 * Attach each generated command to the proper place in the work queue.
 	 * Note this could result in creation of entirely new work-queue entries.
@@ -8176,7 +8210,6 @@ ATPostAlterTypeParse(Oid oldId, char *cmd,
 	foreach(list_item, querytree_list)
 	{
 		Node	   *stm = (Node *) lfirst(list_item);
-		Relation	rel;
 		AlteredTableInfo *tab;
 
 		switch (nodeTag(stm))
@@ -8189,14 +8222,12 @@ ATPostAlterTypeParse(Oid oldId, char *cmd,
 					if (!rewrite)
 						TryReuseIndex(oldId, stmt);
 
-					rel = relation_openrv(stmt->relation, lockmode);
 					tab = ATGetQueueEntry(wqueue, rel);
 					newcmd = makeNode(AlterTableCmd);
 					newcmd->subtype = AT_ReAddIndex;
 					newcmd->def = (Node *) stmt;
 					tab->subcmds[AT_PASS_OLD_INDEX] =
 						lappend(tab->subcmds[AT_PASS_OLD_INDEX], newcmd);
-					relation_close(rel, NoLock);
 					break;
 				}
 			case T_AlterTableStmt:
@@ -8204,7 +8235,6 @@ ATPostAlterTypeParse(Oid oldId, char *cmd,
 					AlterTableStmt *stmt = (AlterTableStmt *) stm;
 					ListCell   *lcmd;
 
-					rel = relation_openrv(stmt->relation, lockmode);
 					tab = ATGetQueueEntry(wqueue, rel);
 					foreach(lcmd, stmt->cmds)
 					{
@@ -8225,6 +8255,7 @@ ATPostAlterTypeParse(Oid oldId, char *cmd,
 							case AT_AddConstraint:
 								Assert(IsA(cmd->def, Constraint));
 								con = (Constraint *) cmd->def;
+								con->old_pktable_oid = refRelId;
 								/* rewriting neither side of a FK */
 								if (con->contype == CONSTR_FOREIGN &&
 									!rewrite && !tab->rewrite)
@@ -8238,7 +8269,6 @@ ATPostAlterTypeParse(Oid oldId, char *cmd,
 									 (int) cmd->subtype);
 						}
 					}
-					relation_close(rel, NoLock);
 					break;
 				}
 			default:
@@ -8246,6 +8276,8 @@ ATPostAlterTypeParse(Oid oldId, char *cmd,
 					 (int) nodeTag(stm));
 		}
 	}
+
+	relation_close(rel, NoLock);
 }
 
 /*
@@ -8256,7 +8288,6 @@ static void
 TryReuseIndex(Oid oldId, IndexStmt *stmt)
 {
 	if (CheckIndexCompatible(oldId,
-							 stmt->relation,
 							 stmt->accessMethod,
 							 stmt->indexParams,
 							 stmt->excludeOpNames))
@@ -10880,6 +10911,38 @@ RangeVarCallbackOwnsTable(const RangeVar *relation,
 }
 
 /*
+ * Callback to RangeVarGetRelidExtended(), similar to
+ * RangeVarCallbackOwnsTable() but without checks on the type of the relation.
+ */
+void
+RangeVarCallbackOwnsRelation(const RangeVar *relation,
+							 Oid relId, Oid oldRelId, void *arg)
+{
+	HeapTuple	tuple;
+
+	/* Nothing to do if the relation was not found. */
+	if (!OidIsValid(relId))
+		return;
+
+	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relId));
+	if (!HeapTupleIsValid(tuple))		/* should not happen */
+		elog(ERROR, "cache lookup failed for relation %u", relId);
+
+	if (!pg_class_ownercheck(relId, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
+					   relation->relname);
+
+	if (!allowSystemTableMods &&
+		IsSystemClass(relId, (Form_pg_class) GETSTRUCT(tuple)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied: \"%s\" is a system catalog",
+						relation->relname)));
+
+	ReleaseSysCache(tuple);
+}
+
+/*
  * Common RangeVarGetRelid callback for rename, set schema, and alter table
  * processing.
  */