wireguard: queueing: make use of ip_tunnel_parse_protocol

Now that wg_examine_packet_protocol has been added for general
consumption as ip_tunnel_parse_protocol, it's possible to remove
wg_examine_packet_protocol and simply use the new
ip_tunnel_parse_protocol function directly.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wireguard/queueing.h

@@ -11,6 +11,7 @@
 #include <linux/skbuff.h>
 #include <linux/ip.h>
 #include <linux/ipv6.h>
+#include <net/ip_tunnels.h>
 
 struct wg_device;
 struct wg_peer;
@@ -65,25 +66,9 @@ struct packet_cb {
 #define PACKET_CB(skb) ((struct packet_cb *)((skb)->cb))
 #define PACKET_PEER(skb) (PACKET_CB(skb)->keypair->entry.peer)
 
-/* Returns either the correct skb->protocol value, or 0 if invalid. */
-static inline __be16 wg_examine_packet_protocol(struct sk_buff *skb)
-{
-	if (skb_network_header(skb) >= skb->head &&
-	    (skb_network_header(skb) + sizeof(struct iphdr)) <=
-		    skb_tail_pointer(skb) &&
-	    ip_hdr(skb)->version == 4)
-		return htons(ETH_P_IP);
-	if (skb_network_header(skb) >= skb->head &&
-	    (skb_network_header(skb) + sizeof(struct ipv6hdr)) <=
-		    skb_tail_pointer(skb) &&
-	    ipv6_hdr(skb)->version == 6)
-		return htons(ETH_P_IPV6);
-	return 0;
-}
-
 static inline bool wg_check_packet_protocol(struct sk_buff *skb)
 {
-	__be16 real_protocol = wg_examine_packet_protocol(skb);
+	__be16 real_protocol = ip_tunnel_parse_protocol(skb);
 	return real_protocol && skb->protocol == real_protocol;
 }
 

drivers/net/wireguard/receive.c

@@ -387,7 +387,7 @@ static void wg_packet_consume_data_done(struct wg_peer *peer,
 	 */
 	skb->ip_summed = CHECKSUM_UNNECESSARY;
 	skb->csum_level = ~0; /* All levels */
-	skb->protocol = wg_examine_packet_protocol(skb);
+	skb->protocol = ip_tunnel_parse_protocol(skb);
 	if (skb->protocol == htons(ETH_P_IP)) {
 		len = ntohs(ip_hdr(skb)->tot_len);
 		if (unlikely(len < sizeof(struct iphdr)))