From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754421AbdJINMV (ORCPT ); Mon, 9 Oct 2017 09:12:21 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:42044 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754290AbdJIMpB (ORCPT ); Mon, 9 Oct 2017 08:45:01 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Jan Kara" , "Ernesto A. =?UTF-8?Q?Fern=C3=A1ndez?=" Date: Mon, 09 Oct 2017 13:44:24 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 120/192] ext3: preserve i_mode if ext2_set_acl() fails In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.49-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Ben Hutchings Based on Ernesto A. Fernández's fix for ext2 (commit fe26569eb919), from which the following description is taken: > When changing a file's acl mask, ext2_set_acl() will first set the group > bits of i_mode to the value of the mask, and only then set the actual > extended attribute representing the new acl. > > If the second part fails (due to lack of space, for example) and the file > had no acl attribute to begin with, the system will from now on assume > that the mask permission bits are actual group permission bits, potentially > granting access to the wrong users. > > Prevent this by only changing the inode mode after the acl has been set. Cc: Ernesto A. Fernández Cc: Jan Kara Signed-off-by: Ben Hutchings --- fs/ext3/acl.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/fs/ext3/acl.c +++ b/fs/ext3/acl.c @@ -227,19 +227,25 @@ ext3_set_acl(struct inode *inode, struct { handle_t *handle; int error, retries = 0; + int update_mode = 0; + umode_t mode = inode->i_mode; retry: handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb)); if (IS_ERR(handle)) return PTR_ERR(handle); if (type == ACL_TYPE_ACCESS && acl) { - error = posix_acl_update_mode(inode, &inode->i_mode, &acl); + error = posix_acl_update_mode(inode, &mode, &acl); if (error) goto journal_stop; + update_mode = 1; + } + error = __ext3_set_acl(handle, inode, type, acl); + if (!error && update_mode) { + inode->i_mode = mode; inode->i_ctime = CURRENT_TIME_SEC; ext3_mark_inode_dirty(handle, inode); } - error = __ext3_set_acl(handle, inode, type, acl); journal_stop: ext3_journal_stop(handle); if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))