CVE request: libcgroup: Failure to verify netlink messages

[Nelson Elhage <nelhage () ksplice com>]

The cgrulesengd program from libcgroup failed to properly verify the
sender of netlink messages, allowing arbitrary users to spoof events
to the daemon, causing it to place processes into incorrect cgroups.

Note that the default configuration of cgrulesengd does not contain
any any rules, so this is probably only usefully exploitable if an
admin have specifically configured cgrulesengd to enforce some policy.

References:
http://sourceforge.net/mailarchive/message.php?msg_id=27102603

- Nelson