From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f196.google.com ([209.85.216.196]:38331 "EHLO mail-qt0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751020AbdHBGSc (ORCPT ); Wed, 2 Aug 2017 02:18:32 -0400 Received: by mail-qt0-f196.google.com with SMTP id p3so3713976qtg.5 for ; Tue, 01 Aug 2017 23:18:32 -0700 (PDT) Date: Wed, 2 Aug 2017 03:18:27 -0300 From: Ernesto =?utf-8?Q?A=2E_Fern=C3=A1ndez?= To: linux-btrfs@vger.kernel.org Cc: Chris Mason , Josef Bacik , David Sterba , Ernesto =?utf-8?Q?A=2E_Fern=C3=A1ndez?= Subject: [PATCH v3] btrfs: preserve i_mode if __btrfs_set_acl() fails Message-ID: <20170802061825.GA8058@debian.home> References: <20170729002626.GA6759@debian.home> <20170730021838.GA4565@debian.home> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 In-Reply-To: <20170730021838.GA4565@debian.home> Sender: linux-btrfs-owner@vger.kernel.org List-ID: When changing a file's acl mask, btrfs_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 restoring the original mode bits if __btrfs_set_acl fails. Signed-off-by: Ernesto A. Fernández --- Please ignore the two previous versions, this is far simpler and has the same effect. To Josef Bacik: thank you for your review, I'm sorry I wasted your time. fs/btrfs/acl.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c index 8d8370d..1ba49eb 100644 --- a/fs/btrfs/acl.c +++ b/fs/btrfs/acl.c @@ -114,13 +114,17 @@ static int __btrfs_set_acl(struct btrfs_trans_handle *trans, int btrfs_set_acl(struct inode *inode, struct posix_acl *acl, int type) { int ret; + umode_t old_mode = inode->i_mode; if (type == ACL_TYPE_ACCESS && acl) { ret = posix_acl_update_mode(inode, &inode->i_mode, &acl); if (ret) return ret; } - return __btrfs_set_acl(NULL, inode, acl, type); + ret = __btrfs_set_acl(NULL, inode, acl, type); + if (ret) + inode->i_mode = old_mode; + return ret; } /* -- 2.1.4