From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764256AbYECM2P (ORCPT ); Sat, 3 May 2008 08:28:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756870AbYECM2A (ORCPT ); Sat, 3 May 2008 08:28:00 -0400 Received: from gustav.zipernowsky.hu ([193.225.20.248]:33730 "EHLO gustav.zipernowsky.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754835AbYECM17 (ORCPT ); Sat, 3 May 2008 08:27:59 -0400 MIME-Version: 1.0 Date: Sat, 03 May 2008 14:27:54 +0200 From: Oliver Pinter To: Miklos Szeredi Cc: linux-kernel@vger.kernel.org, Ulrich Drepper , Michael Kerrisk , Andrew Morton Subject: [OP] 04-vfs-fix-permission-checking-in-sys_utimensat.patch added to queue-2.6.22.23-op1 Reply-To: oliver.pntr@gmail.com Message-ID: <494fd3cee207c1311e9273ef9a4e0b1e@zipernowsky.hu> User-Agent: RoundCube Webmail/0.1 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Your patch added to queue-2.6.22.23-op1. If anyone has any objections, please let us know. http://repo.or.cz/w/linux-2.6.22.y-op-patches.git git://repo.or.cz/linux-2.6.22.y-op-patches.git --- From: Miklos Szeredi Date: Thu, 1 May 2008 04:34:45 -0700 Subject: [PATCH] vfs: fix permission checking in sys_utimensat If utimensat() is called with both times set to UTIME_NOW or one of them to UTIME_NOW and the other to UTIME_OMIT, then it will update the file time without any permission checking. I don't think this can be used for anything other than a local DoS, but could be quite bewildering at that (e.g. "Why was that large source tree rebuilt when I didn't modify anything???") This affects all kernels from 2.6.22, when the utimensat() syscall was introduced. Fix by doing the same permission checking as for the "times == NULL" case. Thanks to Michael Kerrisk, whose utimensat-non-conformances-and-fixes.patch in -mm also fixes this (and breaks other stuff), only he didn't realize the security implications of this bug. Signed-off-by: Miklos Szeredi Cc: Ulrich Drepper Cc: Michael Kerrisk Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Backported-to-2.6.22.y: Oliver Pinter diff --git a/fs/utimes.c b/fs/utimes.c index f28a919..88432eb 100644 --- a/fs/utimes.c +++ b/fs/utimes.c @@ -39,9 +39,14 @@ asmlinkage long sys_utime(char __user *filename, struct utimbuf __user *times) #endif +static bool nsec_special(long nsec) +{ + return nsec == UTIME_OMIT || nsec == UTIME_NOW; +} + static bool nsec_valid(long nsec) { - if (nsec == UTIME_OMIT || nsec == UTIME_NOW) + if (nsec_special(nsec)) return true; return nsec >= 0 && nsec <= 999999999; @@ -115,7 +120,15 @@ long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags newattrs.ia_mtime.tv_nsec = times[1].tv_nsec; newattrs.ia_valid |= ATTR_MTIME_SET; } - } else { + } + + /* + * If times is NULL or both times are either UTIME_OMIT or + * UTIME_NOW, then need to check permissions, because + * inode_change_ok() won't do it. + */ + if (!times || (nsec_special(times[0].tv_nsec) && + nsec_special(times[1].tv_nsec))) { error = -EACCES; if (IS_IMMUTABLE(inode)) goto dput_and_out;