tree b83a95848223a38850d678493e5598200bf814e6
parent 1919981ed9fdf90ed05bd605d4f162833ed2c4c6
author Serge Hallyn <serge.hallyn@ubuntu.com> 1447865805 -0600
committer Serge Hallyn <serge.hallyn@ubuntu.com> 1450840935 -0800

Add FS_USERNS_FLAG to cgroup fs

allowing root in a non-init user namespace to mount it.  This should
now be safe, because

1. non-init-root cannot mount a previously unbound subsystem
2. the task doing the mount must be privileged with respect to the
   user namespace owning the cgroup namespace
3. the mounted subsystem will have its current cgroup as the root dentry.
   the permissions will be unchanged, so tasks will receive no new
   privilege over the cgroups which they did not have on the original
   mounts.

Signed-off-by: Serge Hallyn <serge.hallyn@canonical.com>