[SK_BUFF]: Introduce skb_network_header()

For the places where we need a pointer to the network header, it is still legal
to touch skb->nh.raw directly if just adding to, subtracting from or setting it
to another layer header.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/xfrm6_input.c b/net/ipv6/xfrm6_input.c
index 33a1b92..5c929f8 100644
--- a/net/ipv6/xfrm6_input.c
+++ b/net/ipv6/xfrm6_input.c
@@ -28,7 +28,7 @@
 	unsigned int nhoff;
 
 	nhoff = IP6CB(skb)->nhoff;
-	nexthdr = skb->nh.raw[nhoff];
+	nexthdr = skb_network_header(skb)[nhoff];
 
 	seq = 0;
 	if (!spi && (err = xfrm_parse_spi(skb, nexthdr, &spi, &seq)) != 0)
@@ -58,7 +58,7 @@
 		if (nexthdr <= 0)
 			goto drop_unlock;
 
-		skb->nh.raw[nhoff] = nexthdr;
+		skb_network_header(skb)[nhoff] = nexthdr;
 
 		if (x->props.replay_window)
 			xfrm_replay_advance(x, seq);
@@ -113,7 +113,7 @@
 	} else {
 #ifdef CONFIG_NETFILTER
 		skb->nh.ipv6h->payload_len = htons(skb->len);
-		__skb_push(skb, skb->data - skb->nh.raw);
+		__skb_push(skb, skb->data - skb_network_header(skb));
 
 		NF_HOOK(PF_INET6, NF_IP6_PRE_ROUTING, skb, skb->dev, NULL,
 			ip6_rcv_finish);