tree da5901e5d3b6cc41d7ea30d1fc39be7244254019
parent 1b852bceb0d111e510d1a15826ecc4a19358d512
author Eric W. Biederman <ebiederm@xmission.com> 1431146987 -0500
committer Eric W. Biederman <ebiederm@xmission.com> 1433431765 -0500

mnt: Modify fs_fully_visible to deal with locked ro nodev and atime

Ignore an existing mount if the locked readonly, nodev or atime
attributes are less permissive than the desired attributes
of the new mount.

On success ensure the new mount locks all of the same readonly, nodev and
atime attributes as the old mount.

The nosuid and noexec attributes are not checked here as this change
is destined for stable and enforcing those attributes causes a
regression in lxc and libvirt-lxc where those applications will not
start and there are no known executables on sysfs or proc and no known
way to create exectuables without code modifications

Cc: stable@vger.kernel.org
Fixes: e51db73532955 ("userns: Better restrictions on when proc and sysfs can be mounted")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>