openvswitch: Allow matching on conntrack label

Allow matching and setting the ct_label field. As with ct_mark, this is
populated by executing the CT action. The label field may be modified by
specifying a label and mask nested under the CT action. It is stored as
metadata attached to the connection. Label modification occurs after
lookup, and will only persist when the conntrack entry is committed by
providing the COMMIT flag to the CT action. Labels are currently fixed
to 128 bits in size.

Signed-off-by: Joe Stringer <joestringer@nicira.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/openvswitch/datapath.h

@@ -138,6 +138,9 @@ struct ovs_net {
 	struct list_head dps;
 	struct work_struct dp_notify_work;
 	struct vport_net vport_net;
+
+	/* Module reference for configuring conntrack. */
+	bool xt_label;
 };
 
 extern int ovs_net_id;