Merge branch 'vxlan_group_policy_extension'

Thomas Graf says:

====================
VXLAN Group Policy Extension

Implements supports for the Group Policy VXLAN extension [0] to provide
a lightweight and simple security label mechanism across network peers
based on VXLAN. The security context and associated metadata is mapped
to/from skb->mark. This allows further mapping to a SELinux context
using SECMARK, to implement ACLs directly with nftables, iptables, OVS,
tc, etc.

The extension is disabled by default and should be run on a distinct
port in mixed Linux VXLAN VTEP environments. Liberal VXLAN VTEPs
which ignore unknown reserved bits will be able to receive VXLAN-GBP
frames.

Simple usage example:

10.1.1.1:
   # ip link add vxlan0 type vxlan id 10 remote 10.1.1.2 gbp
   # iptables -I OUTPUT -m owner --uid-owner 101 -j MARK --set-mark 0x200

10.1.1.2:
   # ip link add vxlan0 type vxlan id 10 remote 10.1.1.1 gbp
   # iptables -I INPUT -m mark --mark 0x200 -j DROP

iproute2 [1] and OVS [2] support will be provided in separate patches.

[0] https://tools.ietf.org/html/draft-smith-vxlan-group-policy
[1] https://github.com/tgraf/iproute2/tree/vxlan-gbp
[2] https://github.com/tgraf/ovs/tree/vxlan-gbp
====================

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