gre: Set inner protocol in v4 and v6 GRE transmit

Call skb_set_inner_protocol to set inner Ethernet protocol to
protocol being encapsulation by GRE before tunnel_xmit. This is
needed for GSO 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/ipv4/ip_gre.c

@@ -241,6 +241,8 @@ static void __gre_xmit(struct sk_buff *skb, struct net_device *dev,
 	/* Push GRE header. */
 	gre_build_header(skb, &tpi, tunnel->tun_hlen);
 
+	skb_set_inner_protocol(skb, tpi.proto);
+
 	ip_tunnel_xmit(skb, dev, tnl_params, tnl_params->protocol);
 }
 

net/ipv6/ip6_gre.c

@@ -616,6 +616,7 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
 	int err = -1;
 	u8 proto;
 	struct sk_buff *new_skb;
+	__be16 protocol;
 
 	if (dev->type == ARPHRD_ETHER)
 		IPCB(skb)->flags = 0;
@@ -732,8 +733,9 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
 	ipv6h->daddr = fl6->daddr;
 
 	((__be16 *)(ipv6h + 1))[0] = tunnel->parms.o_flags;
-	((__be16 *)(ipv6h + 1))[1] = (dev->type == ARPHRD_ETHER) ?
-				   htons(ETH_P_TEB) : skb->protocol;
+	protocol = (dev->type == ARPHRD_ETHER) ?
+		    htons(ETH_P_TEB) : skb->protocol;
+	((__be16 *)(ipv6h + 1))[1] = protocol;
 
 	if (tunnel->parms.o_flags&(GRE_KEY|GRE_CSUM|GRE_SEQ)) {
 		__be32 *ptr = (__be32 *)(((u8 *)ipv6h) + tunnel->hlen - 4);
@@ -754,6 +756,8 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
 		}
 	}
 
+	skb_set_inner_protocol(skb, protocol);
+
 	ip6tunnel_xmit(skb, dev);
 	if (ndst)
 		ip6_tnl_dst_store(tunnel, ndst);