netfilter: nf_tables: match on tunnel metadata

This patch allows us to match on the tunnel metadata that is available
of the packet. We can use this to validate if the packet comes from/goes
to tunnel and the corresponding tunnel ID.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/uapi/linux/netfilter/nf_tables.h

@@ -1647,4 +1647,19 @@ enum nft_tunnel_key_attributes {
 };
 #define NFTA_TUNNEL_KEY_MAX	(__NFTA_TUNNEL_KEY_MAX - 1)
 
+enum nft_tunnel_keys {
+	NFT_TUNNEL_PATH,
+	NFT_TUNNEL_ID,
+	__NFT_TUNNEL_MAX
+};
+#define NFT_TUNNEL_MAX	(__NFT_TUNNEL_MAX - 1)
+
+enum nft_tunnel_attributes {
+	NFTA_TUNNEL_UNSPEC,
+	NFTA_TUNNEL_KEY,
+	NFTA_TUNNEL_DREG,
+	__NFTA_TUNNEL_MAX
+};
+#define NFTA_TUNNEL_MAX	(__NFTA_TUNNEL_MAX - 1)
+
 #endif /* _LINUX_NF_TABLES_H */