Adjust permissions checking for ALTER OWNER commands: instead of

requiring superuserness always, allow an owner to reassign ownership
to any role he is a member of, if that role would have the right to
create a similar object.  These three requirements essentially state
that the would-be alterer has enough privilege to DROP the existing
object and then re-CREATE it as the new role; so we might as well
let him do it in one step.  The ALTER TABLESPACE case is a bit
squirrely, but the whole concept of non-superuser tablespace owners
is pretty dubious anyway.  Stephen Frost, code review by Tom Lane.

1 files changed, 17 insertions, 6 deletions

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 2b50a402fc8..c06c272cbdd 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.163 2005/07/07 20:39:58 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.164 2005/07/14 21:46:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -5286,12 +5286,23 @@ ATExecChangeOwner(Oid relationOid, Oid newOwnerId)
 		Datum		aclDatum;
 		bool		isNull;
 		HeapTuple	newtuple;
+		Oid		    namespaceOid = tuple_class->relnamespace;
+		AclResult	aclresult;
 
-		/* Otherwise, check that we are the superuser */
-		if (!superuser())
-			ereport(ERROR,
-					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-					 errmsg("must be superuser to change owner")));
+		/* Otherwise, must be owner of the existing object */
+		if (!pg_class_ownercheck(relationOid,GetUserId()))
+			aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
+						   RelationGetRelationName(target_rel));
+
+		/* Must be able to become new owner */
+		check_is_member_of_role(GetUserId(), newOwnerId);
+
+		/* New owner must have CREATE privilege on namespace */
+		aclresult = pg_namespace_aclcheck(namespaceOid, newOwnerId,
+										  ACL_CREATE);
+		if (aclresult != ACLCHECK_OK)
+			aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
+						   get_namespace_name(namespaceOid));
 
 		memset(repl_null, ' ', sizeof(repl_null));
 		memset(repl_repl, ' ', sizeof(repl_repl));