net/flow_dissector: add connection tracking dissection

Retreives connection tracking zone, mark, label, and state from
a SKB.
Signed-off-by: Paul Blakey <paulb@mellanox.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -1325,6 +1325,16 @@ void skb_flow_dissect_meta(const struct sk_buff *skb,
 			   struct flow_dissector *flow_dissector,
 			   void *target_container);
 
+/* Gets a skb connection tracking info, ctinfo map should be a
+ * a map of mapsize to translate enum ip_conntrack_info states
+ * to user states.
+ */
+void
+skb_flow_dissect_ct(const struct sk_buff *skb,
+		    struct flow_dissector *flow_dissector,
+		    void *target_container,
+		    u16 *ctinfo_map,
+		    size_t mapsize);
 void
 skb_flow_dissect_tunnel_info(const struct sk_buff *skb,
 			     struct flow_dissector *flow_dissector,

include/net/flow_dissector.h

@@ -208,6 +208,20 @@ struct flow_dissector_key_meta {
 	int ingress_ifindex;
 };
 
+/**
+ * struct flow_dissector_key_ct:
+ * @ct_state: conntrack state after converting with map
+ * @ct_mark: conttrack mark
+ * @ct_zone: conntrack zone
+ * @ct_labels: conntrack labels
+ */
+struct flow_dissector_key_ct {
+	u16	ct_state;
+	u16	ct_zone;
+	u32	ct_mark;
+	u32	ct_labels[4];
+};
+
 enum flow_dissector_key_id {
 	FLOW_DISSECTOR_KEY_CONTROL, /* struct flow_dissector_key_control */
 	FLOW_DISSECTOR_KEY_BASIC, /* struct flow_dissector_key_basic */
@@ -234,6 +248,7 @@ enum flow_dissector_key_id {
 	FLOW_DISSECTOR_KEY_ENC_IP, /* struct flow_dissector_key_ip */
 	FLOW_DISSECTOR_KEY_ENC_OPTS, /* struct flow_dissector_key_enc_opts */
 	FLOW_DISSECTOR_KEY_META, /* struct flow_dissector_key_meta */
+	FLOW_DISSECTOR_KEY_CT, /* struct flow_dissector_key_ct */
 
 	FLOW_DISSECTOR_KEY_MAX,
 };

net/core/flow_dissector.c

@@ -27,6 +27,10 @@
 #include <scsi/fc/fc_fcoe.h>
 #include <uapi/linux/batadv_packet.h>
 #include <linux/bpf.h>
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+#include <net/netfilter/nf_conntrack_core.h>
+#include <net/netfilter/nf_conntrack_labels.h>
+#endif
 
 static DEFINE_MUTEX(flow_dissector_mutex);
 
@@ -231,6 +235,46 @@ skb_flow_dissect_set_enc_addr_type(enum flow_dissector_key_id type,
 	ctrl->addr_type = type;
 }
 
+void
+skb_flow_dissect_ct(const struct sk_buff *skb,
+		    struct flow_dissector *flow_dissector,
+		    void *target_container,
+		    u16 *ctinfo_map,
+		    size_t mapsize)
+{
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+	struct flow_dissector_key_ct *key;
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn_labels *cl;
+	struct nf_conn *ct;
+
+	if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_CT))
+		return;
+
+	ct = nf_ct_get(skb, &ctinfo);
+	if (!ct)
+		return;
+
+	key = skb_flow_dissector_target(flow_dissector,
+					FLOW_DISSECTOR_KEY_CT,
+					target_container);
+
+	if (ctinfo < mapsize)
+		key->ct_state = ctinfo_map[ctinfo];
+#if IS_ENABLED(CONFIG_NF_CONNTRACK_ZONES)
+	key->ct_zone = ct->zone.id;
+#endif
+#if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK)
+	key->ct_mark = ct->mark;
+#endif
+
+	cl = nf_ct_labels_find(ct);
+	if (cl)
+		memcpy(key->ct_labels, cl->bits, sizeof(key->ct_labels));
+#endif /* CONFIG_NF_CONNTRACK */
+}
+EXPORT_SYMBOL(skb_flow_dissect_ct);
+
 void
 skb_flow_dissect_tunnel_info(const struct sk_buff *skb,
 			     struct flow_dissector *flow_dissector,