ipv6: gre: fix wrong skb->protocol in WCCP

When using GRE redirection in WCCP, it sets the wrong skb->protocol,
that is, ETH_P_IP instead of ETH_P_IPV6 for the encapuslated traffic.

Fixes: c12b395a ("gre: Support GRE over IPv6")
Cc: Dmitry Kozlov <xeb@mail.ru>
Signed-off-by: Yuri Chislov <yuri.chislov@gmail.com>
Tested-by: Yuri Chislov <yuri.chislov@gmail.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ip6_gre.c

@@ -502,11 +502,11 @@ static int ip6gre_rcv(struct sk_buff *skb)
 
 		skb->protocol = gre_proto;
 		/* WCCP version 1 and 2 protocol decoding.
-		 * - Change protocol to IP
+		 * - Change protocol to IPv6
 		 * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
 		 */
 		if (flags == 0 && gre_proto == htons(ETH_P_WCCP)) {
-			skb->protocol = htons(ETH_P_IP);
+			skb->protocol = htons(ETH_P_IPV6);
 			if ((*(h + offset) & 0xF0) != 0x40)
 				offset += 4;
 		}