tree 4981ef9e44089e03d5865b6d27c0625eccb917d1
parent f507d3bac2286c3f08d50b9c09b838fedfbfa8ee
author Serge Hallyn <serge.hallyn@ubuntu.com> 1447865805 -0600
committer Serge Hallyn <serge.hallyn@ubuntu.com> 1451937066 -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>