tree aa8528c1c23dccbeca409059ec5f5d21ca1318bf
parent 3151527ee007b73a0ebd296010f1c0454a919c7d
author Eric W. Biederman <ebiederm@xmission.com> 1363947015 -0700
committer Eric W. Biederman <ebiederm@xmission.com> 1364395804 -0700

vfs: Add a mount flag to lock read only bind mounts

When a read-only bind mount is copied from mount namespace in a higher
privileged user namespace to a mount namespace in a lesser privileged
user namespace, it should not be possible to remove the the read-only
restriction.

Add a MNT_LOCK_READONLY mount flag to indicate that a mount must
remain read-only.

CC: stable@vger.kernel.org
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>