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[3.16.y-ckt,070/216] mnt: Implicitly add MNT_NODEV on remount when it was implicitly added by mount

Message ID 1421085933-32536-71-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques Jan. 12, 2015, 6:03 p.m. UTC 
3.16.7-ckt4 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Eric W. Biederman" <ebiederm@xmission.com>

commit 3e1866410f11356a9fd869beb3e95983dc79c067 upstream.

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.

Tested-by: Cedric Bosdonnat <cbosdonnat@suse.com>
Tested-by: Richard Weinberger <richard@nod.at>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 fs/namespace.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/fs/namespace.c b/fs/namespace.c
index f24161a45b06..e718c7a0437a 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1973,7 +1973,13 @@  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)) {