From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman) Subject: [CFT][PATCH] mnt: Implicitly add MNT_NODEV on remount when it was implicitly added by mount Date: Sat, 29 Nov 2014 17:05:24 -0600 Message-ID: <87egsllia3.fsf_-_@x220.int.ebiederm.org> References: <20141127101105.GA30605@linux-rxt1.site> <87k32dlicc.fsf@x220.int.ebiederm.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87k32dlicc.fsf-JOvCrm2gF+uungPnsOpG7nhyD016LWXt@public.gmane.org> (Eric W. Biederman's message of "Sat, 29 Nov 2014 17:04:03 -0600") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: joeyli Cc: Stephen Rothwell , Richard Weinberger , Linux Containers , Andy Lutomirski , Jim Fehlig , Cedric Bosdonnat List-Id: containers.vger.kernel.org Now that remount is properly enforcing the rule that you can't remove nodev at least sandstorm.io is breaking when performing a remount. It turns out that there is an easy intuitive solution implicitly add nodev on remount when nodev was implicitly added on mount. Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Signed-off-by: "Eric W. Biederman" --- fs/namespace.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/namespace.c b/fs/namespace.c index 5b66b2b3624d..3a1a87dc33df 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2098,7 +2098,13 @@ static int do_remount(struct path *path, int flags, int mnt_flags, } if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) && !(mnt_flags & MNT_NODEV)) { - return -EPERM; + /* Was the nodev implicitly added in mount? */ + if ((mnt->mnt_ns->user_ns != &init_user_ns) && + !(sb->s_type->fs_flags & FS_USERNS_DEV_MOUNT)) { + mnt_flags |= MNT_NODEV; + } else { + return -EPERM; + } } if ((mnt->mnt.mnt_flags & MNT_LOCK_NOSUID) && !(mnt_flags & MNT_NOSUID)) { -- 1.9.1