From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ipmail03.adl2.internode.on.net ([150.101.137.141]:26737 "EHLO ipmail03.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726393AbfC1V3x (ORCPT ); Thu, 28 Mar 2019 17:29:53 -0400 Date: Fri, 29 Mar 2019 08:29:48 +1100 From: Dave Chinner Subject: Re: [PATCH 3/3] xfs: don't allow most setxattr to immutable files Message-ID: <20190328212948.GL23020@dastard> References: <155379543409.24796.5783716624820175068.stgit@magnolia> <155379545404.24796.5019142212767521955.stgit@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <155379545404.24796.5019142212767521955.stgit@magnolia> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: "Darrick J. Wong" Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-mm@kvack.org On Thu, Mar 28, 2019 at 10:50:54AM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong > > The chattr manpage has this to say about immutable files: > > "A file with the 'i' attribute cannot be modified: it cannot be deleted > or renamed, no link can be created to this file, most of the file's > metadata can not be modified, and the file can not be opened in write > mode." > > However, we don't actually check the immutable flag in the setattr code, > which means that we can update project ids and extent size hints on > supposedly immutable files. Therefore, reject a setattr call on an > immutable file except for the case where we're trying to unset > IMMUTABLE. > > Signed-off-by: Darrick J. Wong > --- > fs/xfs/xfs_ioctl.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c > index 2bd1c5ab5008..9cf0bc0ae2bd 100644 > --- a/fs/xfs/xfs_ioctl.c > +++ b/fs/xfs/xfs_ioctl.c > @@ -1067,6 +1067,14 @@ xfs_ioctl_setattr_xflags( > !capable(CAP_LINUX_IMMUTABLE)) > return -EPERM; > > + /* > + * If immutable is set and we are not clearing it, we're not allowed > + * to change anything else in the inode. > + */ > + if ((ip->i_d.di_flags & XFS_DIFLAG_IMMUTABLE) && > + (fa->fsx_xflags & FS_XFLAG_IMMUTABLE)) > + return -EPERM; > + > /* diflags2 only valid for v3 inodes. */ > di_flags2 = xfs_flags2diflags2(ip, fa->fsx_xflags); > if (di_flags2 && ip->i_d.di_version < 3) Looks fine - catches both FS_IOC_SETFLAGS and FS_IOC_FSSETXATTR for XFS. Do the other filesystems that implement FS_IOC_FSSETXATTR have the same bug? Cheers, Dave. -- Dave Chinner david@fromorbit.com