Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755643AbYFCW0g (ORCPT ); Tue, 3 Jun 2008 18:26:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758605AbYFCWZq (ORCPT ); Tue, 3 Jun 2008 18:25:46 -0400 Received: from mu-out-0910.google.com ([209.85.134.189]:19831 "EHLO mu-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758560AbYFCWZo (ORCPT ); Tue, 3 Jun 2008 18:25:44 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=message-id:date:user-agent:mime-version:to:cc:subject:content-type:content-transfer-encoding:from; b=q0kvcosbd2+d2B5K8rOGEzElX+XTGZ4SnUU3qt9Akl0iJqONYlah8lwEwKocWmjaiCufHus4QcCenK73Z76LxPN2iME+qKFV4vTqufbt9u6leiLGN1q8hGDGBzbwCBXCeSExmerEgX6AvFwM6OnbpK8vzhbv06YD+35icR8oUTY= Message-ID: <4845C4CA.5070403@gmail.com> Date: Wed, 04 Jun 2008 00:25:14 +0200 User-Agent: Thunderbird 2.0.0.6 (X11/20070801) MIME-Version: 1.0 To: Andrew Morton CC: lkml , Christoph Hellwig , Miklos Szeredi , Al Viro , jamie@shareable.org, Ulrich Drepper , linux-fsdevel@vger.kernel.org, Subrata Modak Subject: [parch 3/4] vfs: utimensat(): fix error checking for {UTIME_NOW,UTIME_OMIT} case Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit From: Michael Kerrisk Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2678 Lines: 85 The POSIX.1 draft spec for utimensat() says that to do anything other than setting both timestamps to a time other than the current time (i.e., times is not NULL, and both tv_nsec fields are not UTIME_NOW and both tv_nsec fields are not UTIME_OMIT), either: a) the caller's effective user ID must match the file owner; or b) the caller must have appropriate privileges. If this condition is violated, then the error EPERM should result. However, the current implementation does not generate EPERM if one tv_nsec field is UTIME_NOW while the other is UTIME_OMIT. It should give this error for that case. This patch: a) Repairs that problem. b) Removes the now unneeded nsec_special() helper function. Miklos suggested an alternative idea, migrating the is_owner_or_cap() checks into fs/attr.c:inode_change_ok() via the use of an ATTR_OWNER_CHECK flag. Maybe we could do that later, but for now I've gone with this version, which is simpler, and can be more easily read as being correct. CC: Miklos Szeredi CC: Al Viro CC: Ulrich Drepper Signed-off-by: Michael Kerrisk --- linux-2.6.26-rc4/fs/utimes.c 2008-06-03 23:11:53.000000000 +0200 +++ linux-2.6.26-rc4-utimensat-fix-v4/fs/utimes.c 2008-06-03 23:04:48.000000000 +0200 @@ -40,14 +40,9 @@ #endif -static bool nsec_special(long nsec) -{ - return nsec == UTIME_OMIT || nsec == UTIME_NOW; -} - static bool nsec_valid(long nsec) { - if (nsec_special(nsec)) + if (nsec == UTIME_OMIT || nsec == UTIME_NOW) return true; return nsec >= 0 && nsec <= 999999999; @@ -135,8 +130,7 @@ * 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))) { + if (!times) { error = -EACCES; if (IS_IMMUTABLE(inode)) goto mnt_drop_write_and_out; @@ -151,6 +145,18 @@ goto mnt_drop_write_and_out; } } + } else if ((times[0].tv_nsec == UTIME_NOW && + times[1].tv_nsec == UTIME_OMIT) + || + (times[0].tv_nsec == UTIME_OMIT && + times[1].tv_nsec == UTIME_NOW)) { + error =-EPERM; + + if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) + goto mnt_drop_write_and_out; + + if (!is_owner_or_cap(inode)) + goto mnt_drop_write_and_out; } mutex_lock(&inode->i_mutex); error = notify_change(dentry, &newattrs); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/