net/flow_dissector: Add support for QinQ dissection

Dissect the QinQ packets to get both outer and inner vlan information,
then store to the extended flow keys.

Signed-off-by: Jianbo Liu <jianbol@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/flow_dissector.h

@@ -206,6 +206,7 @@ enum flow_dissector_key_id {
 	FLOW_DISSECTOR_KEY_MPLS, /* struct flow_dissector_key_mpls */
 	FLOW_DISSECTOR_KEY_TCP, /* struct flow_dissector_key_tcp */
 	FLOW_DISSECTOR_KEY_IP, /* struct flow_dissector_key_ip */
+	FLOW_DISSECTOR_KEY_CVLAN, /* struct flow_dissector_key_flow_vlan */
 
 	FLOW_DISSECTOR_KEY_MAX,
 };
@@ -237,6 +238,7 @@ struct flow_keys {
 	struct flow_dissector_key_basic basic;
 	struct flow_dissector_key_tags tags;
 	struct flow_dissector_key_vlan vlan;
+	struct flow_dissector_key_vlan cvlan;
 	struct flow_dissector_key_keyid keyid;
 	struct flow_dissector_key_ports ports;
 	struct flow_dissector_key_addrs addrs;

net/core/flow_dissector.c

@@ -589,7 +589,7 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
 	struct flow_dissector_key_tags *key_tags;
 	struct flow_dissector_key_vlan *key_vlan;
 	enum flow_dissect_ret fdret;
-	bool skip_vlan = false;
+	enum flow_dissector_key_id dissector_vlan = FLOW_DISSECTOR_KEY_MAX;
 	int num_hdrs = 0;
 	u8 ip_proto = 0;
 	bool ret;
@@ -748,15 +748,14 @@ proto_again:
 	}
 	case htons(ETH_P_8021AD):
 	case htons(ETH_P_8021Q): {
-		const struct vlan_hdr *vlan;
+		const struct vlan_hdr *vlan = NULL;
 		struct vlan_hdr _vlan;
-		bool vlan_tag_present = skb && skb_vlan_tag_present(skb);
 		__be16 saved_vlan_tpid = proto;
 
-		if (vlan_tag_present)
+		if (dissector_vlan == FLOW_DISSECTOR_KEY_MAX &&
+		    skb && skb_vlan_tag_present(skb)) {
 			proto = skb->protocol;
-
-		if (!vlan_tag_present || eth_type_vlan(skb->protocol)) {
+		} else {
 			vlan = __skb_header_pointer(skb, nhoff, sizeof(_vlan),
 						    data, hlen, &_vlan);
 			if (!vlan) {
@@ -766,20 +765,23 @@ proto_again:
 
 			proto = vlan->h_vlan_encapsulated_proto;
 			nhoff += sizeof(*vlan);
-			if (skip_vlan) {
-				fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
-				break;
-			}
 		}
 
-		skip_vlan = true;
-		if (dissector_uses_key(flow_dissector,
-				       FLOW_DISSECTOR_KEY_VLAN)) {
+		if (dissector_vlan == FLOW_DISSECTOR_KEY_MAX) {
+			dissector_vlan = FLOW_DISSECTOR_KEY_VLAN;
+		} else if (dissector_vlan == FLOW_DISSECTOR_KEY_VLAN) {
+			dissector_vlan = FLOW_DISSECTOR_KEY_CVLAN;
+		} else {
+			fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
+			break;
+		}
+
+		if (dissector_uses_key(flow_dissector, dissector_vlan)) {
 			key_vlan = skb_flow_dissector_target(flow_dissector,
-							     FLOW_DISSECTOR_KEY_VLAN,
+							     dissector_vlan,
 							     target_container);
 
-			if (vlan_tag_present) {
+			if (!vlan) {
 				key_vlan->vlan_id = skb_vlan_tag_get_id(skb);
 				key_vlan->vlan_priority =
 					(skb_vlan_tag_get_prio(skb) >> VLAN_PRIO_SHIFT);