fib: Add fib rule match on tunnel id

This add the ability to select a routing table based on the tunnel
id which allows to maintain separate routing tables for each virtual
tunnel network.

ip rule add from all tunnel-id 100 lookup 100
ip rule add from all tunnel-id 200 lookup 200

A new static key controls the collection of metadata at tunnel level
upon demand.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
index 903a55e..4e8f804 100644
--- a/include/net/fib_rules.h
+++ b/include/net/fib_rules.h
@@ -19,6 +19,7 @@
 	u8			action;
 	/* 3 bytes hole, try to use */
 	u32			target;
+	__be64			tun_id;
 	struct fib_rule __rcu	*ctarget;
 	struct net		*fr_net;
 
diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
index 0b7e18c..0a5a776 100644
--- a/include/net/ip_tunnels.h
+++ b/include/net/ip_tunnels.h
@@ -303,6 +303,17 @@
 	return (struct ip_tunnel_info *)lwtstate->data;
 }
 
+extern struct static_key ip_tunnel_metadata_cnt;
+
+/* Returns > 0 if metadata should be collected */
+static inline int ip_tunnel_collect_metadata(void)
+{
+	return static_key_false(&ip_tunnel_metadata_cnt);
+}
+
+void ip_tunnel_need_metadata(void);
+void ip_tunnel_unneed_metadata(void);
+
 #endif /* CONFIG_INET */
 
 #endif /* __NET_IP_TUNNELS_H */