[SK_BUFF]: Introduce ip_hdr(), remove skb->nh.iph

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/xfrm4_output.c b/net/ipv4/xfrm4_output.c
index 038ca16..44ef208 100644
--- a/net/ipv4/xfrm4_output.c
+++ b/net/ipv4/xfrm4_output.c
@@ -22,14 +22,13 @@
 {
 	int mtu, ret = 0;
 	struct dst_entry *dst;
-	struct iphdr *iph = skb->nh.iph;
 
 	if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
 		goto out;
 
 	IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
 
-	if (!(iph->frag_off & htons(IP_DF)) || skb->local_df)
+	if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)
 		goto out;
 
 	dst = skb->dst;