flow_dissector: allow dissection of tunnel options from metadata

Allow the existing 'dissection' of tunnel metadata to 'dissect'
options already present in tunnel metadata. This dissection is
controlled by a new dissector key, FLOW_DISSECTOR_KEY_ENC_OPTS.

This dissection only occurs when skb_flow_dissect_tunnel_info()
is called, currently only the Flower classifier makes that call.
So there should be no impact on other users of the flow dissector.

This is in preparation for allowing the flower classifier to
match on Geneve options.

Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/flow_dissector.h

@@ -57,6 +57,21 @@ struct flow_dissector_key_mpls {
 		mpls_label:20;
 };
 
+#define FLOW_DIS_TUN_OPTS_MAX 255
+/**
+ * struct flow_dissector_key_enc_opts:
+ * @data: tunnel option data
+ * @len: length of tunnel option data
+ * @dst_opt_type: tunnel option type
+ */
+struct flow_dissector_key_enc_opts {
+	u8 data[FLOW_DIS_TUN_OPTS_MAX];	/* Using IP_TUNNEL_OPTS_MAX is desired
+					 * here but seems difficult to #include
+					 */
+	u8 len;
+	__be16 dst_opt_type;
+};
+
 struct flow_dissector_key_keyid {
 	__be32	keyid;
 };
@@ -208,6 +223,8 @@ enum flow_dissector_key_id {
 	FLOW_DISSECTOR_KEY_IP, /* struct flow_dissector_key_ip */
 	FLOW_DISSECTOR_KEY_CVLAN, /* struct flow_dissector_key_flow_vlan */
 	FLOW_DISSECTOR_KEY_ENC_IP, /* struct flow_dissector_key_ip */
+	FLOW_DISSECTOR_KEY_ENC_OPTS, /* struct flow_dissector_key_enc_opts */
+
 	FLOW_DISSECTOR_KEY_MAX,
 };
 

net/core/flow_dissector.c

@@ -154,7 +154,9 @@ skb_flow_dissect_tunnel_info(const struct sk_buff *skb,
 	    !dissector_uses_key(flow_dissector,
 				FLOW_DISSECTOR_KEY_ENC_PORTS) &&
 	    !dissector_uses_key(flow_dissector,
-				FLOW_DISSECTOR_KEY_ENC_IP))
+				FLOW_DISSECTOR_KEY_ENC_IP) &&
+	    !dissector_uses_key(flow_dissector,
+				FLOW_DISSECTOR_KEY_ENC_OPTS))
 		return;
 
 	info = skb_tunnel_info(skb);
@@ -224,6 +226,21 @@ skb_flow_dissect_tunnel_info(const struct sk_buff *skb,
 		ip->tos = key->tos;
 		ip->ttl = key->ttl;
 	}
+
+	if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_OPTS)) {
+		struct flow_dissector_key_enc_opts *enc_opt;
+
+		enc_opt = skb_flow_dissector_target(flow_dissector,
+						    FLOW_DISSECTOR_KEY_ENC_OPTS,
+						    target_container);
+
+		if (info->options_len) {
+			enc_opt->len = info->options_len;
+			ip_tunnel_info_opts_get(enc_opt->data, info);
+			enc_opt->dst_opt_type = info->key.tun_flags &
+						TUNNEL_OPTIONS_PRESENT;
+		}
+	}
 }
 EXPORT_SYMBOL(skb_flow_dissect_tunnel_info);