Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751348AbaJOXHJ (ORCPT ); Wed, 15 Oct 2014 19:07:09 -0400 Received: from mail-wi0-f171.google.com ([209.85.212.171]:39737 "EHLO mail-wi0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750870AbaJOXHG (ORCPT ); Wed, 15 Oct 2014 19:07:06 -0400 Date: Thu, 16 Oct 2014 01:07:01 +0200 From: Seth Forshee To: Andy Lutomirski Cc: Miklos Szeredi , fuse-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Eric W. Biederman" , "Serge H. Hallyn" , Seth Forshee Subject: Re: [PATCH v4 5/5] fuse: Allow user namespace mounts Message-ID: <20141015230701.GD988@ubuntu-mba51> Mail-Followup-To: Andy Lutomirski , Miklos Szeredi , fuse-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Eric W. Biederman" , "Serge H. Hallyn" References: <1413296756-25071-1-git-send-email-seth.forshee@canonical.com> <1413296756-25071-6-git-send-email-seth.forshee@canonical.com> <543E8BAD.7000207@mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <543E8BAD.7000207@mit.edu> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 15, 2014 at 07:58:53AM -0700, Andy Lutomirski wrote: > On 10/14/2014 07:25 AM, Seth Forshee wrote: > > Cc: Eric W. Biederman > > Cc: Serge H. Hallyn > > Signed-off-by: Seth Forshee > > --- > > fs/fuse/inode.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c > > index 5e00a6a76049..6522926b14e4 100644 > > --- a/fs/fuse/inode.c > > +++ b/fs/fuse/inode.c > > @@ -1212,7 +1212,7 @@ static void fuse_kill_sb_anon(struct super_block *sb) > > static struct file_system_type fuse_fs_type = { > > .owner = THIS_MODULE, > > .name = "fuse", > > - .fs_flags = FS_HAS_SUBTYPE, > > + .fs_flags = FS_HAS_SUBTYPE | FS_USERNS_MOUNT, > > .mount = fuse_mount, > > .kill_sb = fuse_kill_sb_anon, > > }; > > @@ -1244,7 +1244,7 @@ static struct file_system_type fuseblk_fs_type = { > > .name = "fuseblk", > > .mount = fuse_mount_blk, > > .kill_sb = fuse_kill_sb_blk, > > - .fs_flags = FS_REQUIRES_DEV | FS_HAS_SUBTYPE, > > + .fs_flags = FS_REQUIRES_DEV | FS_HAS_SUBTYPE | FS_USERNS_MOUNT, > > I think it's decision time -- if these patches are applied, then FUSE > will be the first filesystem for which userns nodev behavior matters for > security, so applying this patch will enshrine an API decision. > > I would very much prefer to make this patch depend on this: > > http://lkml.kernel.org/g/2686c32f00b14148379e8cfee9c028c794d4aa1a.1407974494.git.luto@amacapital.net > > That change will require that anyone who tries to mount one of these > things explicitly requests MS_NODEV instead of keeping the current > behavior of implicitly setting MS_NODEV and possibly confusing user code > that tries to remount. > > If you like my patch, feel free to fold it in to your series, or Eric > can apply it directly (pretty please). > > For background, with your patches as is, if you mount a FUSE fs and then > remount it with identical flags, the remount is likely to fail. (Resending my response since I still don't see it on lkml after 7+ hours) I discussed this with Eric during LinuxCon NA ... as I recall he was undecided about whether or not to use your patch at the time. I do prefer an explicit failure over implicitly adding MS_NODEV, but it's not up to me. I do agree though that we should make a decision before merging the fuse patches, I was just assuming that the decision was already made. Thanks, Seth -- 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/