Move permissions check from do_pg_start_backup to pg_start_backup

mhagander · mhagander · commit 026a91f86c19 · 2014-01-07T18:00:36.000+01:00
And the same for do_pg_stop_backup. The code in do_pg_* is not allowed
to access the catalogs. For manual base backups, the permissions
check can be handled in the calling function, and for streaming
base backups only users with the required permissions can get past
the authentication step in the first place.

Reported by Antonin Houska, diagnosed by Andres Freund
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
@@ -8957,6 +8957,11 @@ pg_start_backup(PG_FUNCTION_ARGS)
 
 	backupidstr = text_to_cstring(backupid);
 
+	if (!superuser() && !has_rolreplication(GetUserId()))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser or replication role to run a backup")));
+
 	startpoint = do_pg_start_backup(backupidstr, fast, NULL);
 
 	snprintf(startxlogstr, sizeof(startxlogstr), "%X/%X",
@@ -8984,6 +8989,9 @@ pg_start_backup(PG_FUNCTION_ARGS)
  *
  * Every successfully started non-exclusive backup must be stopped by calling
  * do_pg_stop_backup() or do_pg_abort_backup().
+ *
+ * It is the responsibility of the caller of this function to verify the
+ * permissions of the calling user!
  */
 XLogRecPtr
 do_pg_start_backup(const char *backupidstr, bool fast, char **labelfile)
@@ -9000,11 +9008,6 @@ do_pg_start_backup(const char *backupidstr, bool fast, char **labelfile)
 	FILE	   *fp;
 	StringInfoData labelfbuf;
 
-	if (!superuser() && !has_rolreplication(GetUserId()))
-		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-		   errmsg("must be superuser or replication role to run a backup")));
-
 	if (RecoveryInProgress())
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
@@ -9241,6 +9244,11 @@ pg_stop_backup(PG_FUNCTION_ARGS)
 	XLogRecPtr	stoppoint;
 	char		stopxlogstr[MAXFNAMELEN];
 
+	if (!superuser() && !has_rolreplication(GetUserId()))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser or replication role to run a backup")));
+
 	stoppoint = do_pg_stop_backup(NULL, true);
 
 	snprintf(stopxlogstr, sizeof(stopxlogstr), "%X/%X",
@@ -9254,6 +9262,9 @@ pg_stop_backup(PG_FUNCTION_ARGS)
 
  * If labelfile is NULL, this stops an exclusive backup. Otherwise this stops
  * the non-exclusive backup specified by 'labelfile'.
+ *
+ * It is the responsibility of the caller of this function to verify the
+ * permissions of the calling user!
  */
 XLogRecPtr
 do_pg_stop_backup(char *labelfile, bool waitforarchive)
@@ -9279,11 +9290,6 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive)
 	bool		reported_waiting = false;
 	char	   *remaining;
 
-	if (!superuser() && !has_rolreplication(GetUserId()))
-		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-		 (errmsg("must be superuser or replication role to run a backup"))));
-
 	if (RecoveryInProgress())
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
