iptunnel: specify protocol outside IP header

Before this patch, ip_tunnel_xmit() was using the field protocol from the IP
header passed into argument.
There is no functional change, this patch prepares the support of IPv4 over
IPv4 for module sit.
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip_tunnels.h

@@ -101,7 +101,7 @@ int __net_init ip_tunnel_init_net(struct net *net, int ip_tnl_net_id,
 void __net_exit ip_tunnel_delete_net(struct ip_tunnel_net *itn);
 
 void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
-		    const struct iphdr *tnl_params);
+		    const struct iphdr *tnl_params, const u8 protocol);
 int ip_tunnel_ioctl(struct net_device *dev, struct ip_tunnel_parm *p, int cmd);
 int ip_tunnel_change_mtu(struct net_device *dev, int new_mtu);
 

net/ipv4/ip_gre.c

@@ -429,7 +429,7 @@ static void __gre_xmit(struct sk_buff *skb, struct net_device *dev,
 		return;
 	}
 
-	ip_tunnel_xmit(skb, dev, tnl_params);
+	ip_tunnel_xmit(skb, dev, tnl_params, tnl_params->protocol);
 }
 
 static netdev_tx_t ipgre_xmit(struct sk_buff *skb,

net/ipv4/ip_tunnel.c

@@ -487,7 +487,7 @@ int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct sk_buff *skb,
 EXPORT_SYMBOL_GPL(ip_tunnel_rcv);
 
 void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
-		    const struct iphdr *tnl_params)
+		    const struct iphdr *tnl_params, const u8 protocol)
 {
 	struct ip_tunnel *tunnel = netdev_priv(dev);
 	const struct iphdr *inner_iph;
@@ -670,7 +670,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 	iph->version	=	4;
 	iph->ihl	=	sizeof(struct iphdr) >> 2;
 	iph->frag_off	=	df;
-	iph->protocol	=	tnl_params->protocol;
+	iph->protocol	=	protocol;
 	iph->tos	=	ip_tunnel_ecn_encap(tos, inner_iph, skb);
 	iph->daddr	=	fl4.daddr;
 	iph->saddr	=	fl4.saddr;

net/ipv4/ipip.c

@@ -222,7 +222,7 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 		skb->encapsulation = 1;
 	}
 
-	ip_tunnel_xmit(skb, dev, tiph);
+	ip_tunnel_xmit(skb, dev, tiph, tiph->protocol);
 	return NETDEV_TX_OK;
 
 tx_error: