ipv4: Multipath hashing on inner L3 needs to consider inner IPv6 pkts

Commit 363887a2 ("ipv4: Support multipath hashing on inner IP pkts
for GRE tunnel") supports multipath policy value of 2, Layer 3 or inner
Layer 3 if present, but it only considers inner IPv4. There is a use
case of IPv6 is tunneled by IPv4 GRE, thus add the ability to hash on
inner IPv6 addresses.

Fixes: 363887a2 ("ipv4: Support multipath hashing on inner IP pkts for GRE tunnel")
Signed-off-by: Stephen Suryaputra <ssuryaextr@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/route.c

@@ -1964,17 +1964,30 @@ int fib_multipath_hash(const struct net *net, const struct flowi4 *fl4,
 		break;
 	case 2:
 		memset(&hash_keys, 0, sizeof(hash_keys));
-		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
 		/* skb is currently provided only when forwarding */
 		if (skb) {
 			struct flow_keys keys;
 
 			skb_flow_dissect_flow_keys(skb, &keys, 0);
-
-			hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
-			hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
+			/* Inner can be v4 or v6 */
+			if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV4_ADDRS) {
+				hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
+				hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
+				hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
+			} else if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV6_ADDRS) {
+				hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
+				hash_keys.addrs.v6addrs.src = keys.addrs.v6addrs.src;
+				hash_keys.addrs.v6addrs.dst = keys.addrs.v6addrs.dst;
+				hash_keys.tags.flow_label = keys.tags.flow_label;
+				hash_keys.basic.ip_proto = keys.basic.ip_proto;
+			} else {
+				/* Same as case 0 */
+				hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
+				ip_multipath_l3_keys(skb, &hash_keys);
+			}
 		} else {
 			/* Same as case 0 */
+			hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
 			hash_keys.addrs.v4addrs.src = fl4->saddr;
 			hash_keys.addrs.v4addrs.dst = fl4->daddr;
 		}