sit: Set inner IP protocol in sit

Call skb_set_inner_ipproto to set inner IP protocol to IPPROTO_IPV6
before tunnel_xmit. This is needed if UDP encapsulation (fou) is
being done.
Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/sit.c

@@ -982,6 +982,8 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 		goto tx_error;
 	}
 
+	skb_set_inner_ipproto(skb, IPPROTO_IPV6);
+
 	err = iptunnel_xmit(skb->sk, rt, skb, fl4.saddr, fl4.daddr,
 			    protocol, tos, ttl, df,
 			    !net_eq(tunnel->net, dev_net(dev)));
@@ -1006,6 +1008,8 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (IS_ERR(skb))
 		goto out;
 
+	skb_set_inner_ipproto(skb, IPPROTO_IPIP);
+
 	ip_tunnel_xmit(skb, dev, tiph, IPPROTO_IPIP);
 	return NETDEV_TX_OK;
 out: