Fix "unexpected relkind" error when denying permissions on toast tables.

get_relkind_objtype, and hence get_object_type, failed when applied to a
toast table.  This is not a good thing, because it prevents reporting of
perfectly legitimate permissions errors.  (At present, these functions
are in fact *only* used to determine the ObjectType argument for
acl_error() calls.)  It seems best to have them fall back to returning
OBJECT_TABLE in every case where they can't determine an object type
for a pg_class entry, so do that.

In passing, make some edits to alter.c to make it more obvious that
those calls of get_object_type() are used only for error reporting.
This might save a few cycles in the non-error code path, too.

Back-patch to v11 where this issue originated.

John Hsu, Michael Paquier, Tom Lane

Discussion: https://postgr.es/m/C652D3DF-2B0C-4128-9420-FB5379F6B1E4@amazon.com

2 files changed, 26 insertions, 14 deletions

diff --git a/src/backend/catalog/objectaddress.c b/src/backend/catalog/objectaddress.c
index caf48cefa98..fb6e7190278 100644
--- a/src/backend/catalog/objectaddress.c
+++ b/src/backend/catalog/objectaddress.c
@@ -2612,6 +2612,13 @@ get_object_attnum_acl(Oid class_id)
 	return prop->attnum_acl;
 }
 
+/*
+ * get_object_type
+ *
+ * Return the object type associated with a given object.  This routine
+ * is primarily used to determine the object type to mention in ACL check
+ * error messages, so it's desirable for it to avoid failing.
+ */
 ObjectType
 get_object_type(Oid class_id, Oid object_id)
 {
@@ -5333,6 +5340,16 @@ strlist_to_textarray(List *list)
 	return arr;
 }
 
+/*
+ * get_relkind_objtype
+ *
+ * Return the object type for the relkind given by the caller.
+ *
+ * If an unexpected relkind is passed, we say OBJECT_TABLE rather than
+ * failing.  That's because this is mostly used for generating error messages
+ * for failed ACL checks on relations, and we'd rather produce a generic
+ * message saying "table" than fail entirely.
+ */
 ObjectType
 get_relkind_objtype(char relkind)
 {
@@ -5352,13 +5369,10 @@ get_relkind_objtype(char relkind)
 			return OBJECT_MATVIEW;
 		case RELKIND_FOREIGN_TABLE:
 			return OBJECT_FOREIGN_TABLE;
-
-			/*
-			 * other relkinds are not supported here because they don't map to
-			 * OBJECT_* values
-			 */
+		case RELKIND_TOASTVALUE:
+			return OBJECT_TABLE;
 		default:
-			elog(ERROR, "unexpected relkind: %d", relkind);
-			return 0;
+			/* Per above, don't raise an error */
+			return OBJECT_TABLE;
 	}
 }
diff --git a/src/backend/commands/alter.c b/src/backend/commands/alter.c
index 70dbcb0756c..562e3d3455c 100644
--- a/src/backend/commands/alter.c
+++ b/src/backend/commands/alter.c
@@ -172,7 +172,6 @@ AlterObjectRename_internal(Relation rel, Oid objectId, const char *new_name)
 	AttrNumber	Anum_name = get_object_attnum_name(classId);
 	AttrNumber	Anum_namespace = get_object_attnum_namespace(classId);
 	AttrNumber	Anum_owner = get_object_attnum_owner(classId);
-	ObjectType	objtype = get_object_type(classId, objectId);
 	HeapTuple	oldtup;
 	HeapTuple	newtup;
 	Datum		datum;
@@ -224,7 +223,8 @@ AlterObjectRename_internal(Relation rel, Oid objectId, const char *new_name)
 		ownerId = DatumGetObjectId(datum);
 
 		if (!has_privs_of_role(GetUserId(), DatumGetObjectId(ownerId)))
-			aclcheck_error(ACLCHECK_NOT_OWNER, objtype, old_name);
+			aclcheck_error(ACLCHECK_NOT_OWNER, get_object_type(classId, objectId),
+						   old_name);
 
 		/* User must have CREATE privilege on the namespace */
 		if (OidIsValid(namespaceId))
@@ -670,7 +670,6 @@ AlterObjectNamespace_internal(Relation rel, Oid objid, Oid nspOid)
 	AttrNumber	Anum_name = get_object_attnum_name(classId);
 	AttrNumber	Anum_namespace = get_object_attnum_namespace(classId);
 	AttrNumber	Anum_owner = get_object_attnum_owner(classId);
-	ObjectType	objtype = get_object_type(classId, objid);
 	Oid			oldNspOid;
 	Datum		name,
 				namespace;
@@ -726,7 +725,7 @@ AlterObjectNamespace_internal(Relation rel, Oid objid, Oid nspOid)
 		ownerId = DatumGetObjectId(owner);
 
 		if (!has_privs_of_role(GetUserId(), ownerId))
-			aclcheck_error(ACLCHECK_NOT_OWNER, objtype,
+			aclcheck_error(ACLCHECK_NOT_OWNER, get_object_type(classId, objid),
 						   NameStr(*(DatumGetName(name))));
 
 		/* User must have CREATE privilege on new namespace */
@@ -950,8 +949,6 @@ AlterObjectOwner_internal(Relation rel, Oid objectId, Oid new_ownerId)
 		/* Superusers can bypass permission checks */
 		if (!superuser())
 		{
-			ObjectType	objtype = get_object_type(classId, objectId);
-
 			/* must be owner */
 			if (!has_privs_of_role(GetUserId(), old_ownerId))
 			{
@@ -970,7 +967,8 @@ AlterObjectOwner_internal(Relation rel, Oid objectId, Oid new_ownerId)
 					snprintf(namebuf, sizeof(namebuf), "%u", objectId);
 					objname = namebuf;
 				}
-				aclcheck_error(ACLCHECK_NOT_OWNER, objtype, objname);
+				aclcheck_error(ACLCHECK_NOT_OWNER, get_object_type(classId, objectId),
+							   objname);
 			}
 			/* Must be able to become new owner */
 			check_is_member_of_role(GetUserId(), new_ownerId);