Merge branch 'bpf-Add-option-to-set-mark-and-priority-in-cgroup-sock-programs'

David Ahern says:

====================
bpf: Add option to set mark and priority in cgroup sock programs

Add option to set mark and priority in addition to bound device for newly
created sockets. Also, allow the bpf programs to use the get_current_uid_gid
helper meaning socket marks, priority and device can be set based on the
uid/gid of the running process.

Sample programs are updated to demonstrate the new options.

v3
- no changes to Patches 1 and 2 which Alexei acked in previous versions
- dropped change related to recursive programs in a cgroup
- updated tests per dropped patch

v2
- added flag to control recursive behavior as requested by Alexei
- added comment to sock_filter_func_proto regarding use of
  get_current_uid_gid helper
- updated test programs for recursive option
====================

Signed-off-by: David S. Miller <davem@davemloft.net>