[IPSEC]: Get rid of ipv6_{auth,esp,comp}_hdr

This patch removes the duplicate ipv6_{auth,esp,comp}_hdr structures since
they're identical to the IPv4 versions.  Duplicating them would only create
problems for ourselves later when we need to add things like extended
sequence numbers.

I've also added transport header type conversion headers for these types
which are now used by the transforms.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ah4.c b/net/ipv4/ah4.c
index e4f7aa39..d697064 100644
--- a/net/ipv4/ah4.c
+++ b/net/ipv4/ah4.c
@@ -82,7 +82,7 @@
 			goto error;
 	}
 
-	ah = (struct ip_auth_hdr *)skb_transport_header(skb);
+	ah = ip_auth_hdr(skb);
 	ah->nexthdr = *skb_mac_header(skb);
 	*skb_mac_header(skb) = IPPROTO_AH;
 
@@ -93,8 +93,7 @@
 	top_iph->check = 0;
 
 	ahp = x->data;
-	ah->hdrlen  = (XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
-				   ahp->icv_trunc_len) >> 2) - 2;
+	ah->hdrlen  = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
 
 	ah->reserved = 0;
 	ah->spi = x->id.spi;
@@ -134,15 +133,15 @@
 	struct ah_data *ahp;
 	char work_buf[60];
 
-	if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
+	if (!pskb_may_pull(skb, sizeof(*ah)))
 		goto out;
 
-	ah = (struct ip_auth_hdr*)skb->data;
+	ah = (struct ip_auth_hdr *)skb->data;
 	ahp = x->data;
 	ah_hlen = (ah->hdrlen + 2) << 2;
 
-	if (ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_full_len) &&
-	    ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len))
+	if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
+	    ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
 		goto out;
 
 	if (!pskb_may_pull(skb, ah_hlen))
@@ -156,7 +155,7 @@
 
 	skb->ip_summed = CHECKSUM_NONE;
 
-	ah = (struct ip_auth_hdr*)skb->data;
+	ah = (struct ip_auth_hdr *)skb->data;
 	iph = ip_hdr(skb);
 
 	ihl = skb->data - skb_network_header(skb);
@@ -266,7 +265,8 @@
 	if (!ahp->work_icv)
 		goto error;
 
-	x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len);
+	x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
+					  ahp->icv_trunc_len);
 	if (x->props.mode == XFRM_MODE_TUNNEL)
 		x->props.header_len += sizeof(struct iphdr);
 	x->data = ahp;