[IPSEC]: Separate inner/outer mode processing on input

With inter-family transforms the inner mode differs from the outer
mode.  Attempting to handle both sides from the same function means
that it needs to handle both IPv4 and IPv6 which creates duplication
and confusion.

This patch separates the two parts on the input path so that each
function deals with one family only.

In particular, the functions xfrm4_extract_inut/xfrm6_extract_inut
moves the pertinent fields from the IPv4/IPv6 IP headers into a
neutral format stored in skb->cb.  This is then used by the inner mode
input functions to modify the inner IP header.  In this way the input
function no longer has to know about the outer address family.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 34 deletions

diff --git a/net/ipv4/xfrm4_mode_tunnel.c b/net/ipv4/xfrm4_mode_tunnel.c
index cc8bbb2..aa335db 100644
--- a/net/ipv4/xfrm4_mode_tunnel.c
+++ b/net/ipv4/xfrm4_mode_tunnel.c
@@ -16,19 +16,12 @@
 
 static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
 {
-	struct iphdr *outer_iph = ip_hdr(skb);
 	struct iphdr *inner_iph = ipip_hdr(skb);
 
-	if (INET_ECN_is_ce(outer_iph->tos))
+	if (INET_ECN_is_ce(XFRM_MODE_SKB_CB(skb)->tos))
 		IP_ECN_set_ce(inner_iph);
 }
 
-static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
-{
-	if (INET_ECN_is_ce(iph->tos))
-		IP6_ECN_set_ce(ipv6_hdr(skb));
-}
-
 /* Add encapsulation header.
  *
  * The top IP header will be constructed per RFC 2401.
@@ -72,20 +65,11 @@ static int xfrm4_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
 
 static int xfrm4_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
 {
-	struct iphdr *iph = ip_hdr(skb);
 	const unsigned char *old_mac;
 	int err = -EINVAL;
 
-	switch (iph->protocol){
-		case IPPROTO_IPIP:
-			break;
-#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
-		case IPPROTO_IPV6:
-			break;
-#endif
-		default:
-			goto out;
-	}
+	if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPIP)
+		goto out;
 
 	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 		goto out;
@@ -94,20 +78,11 @@ static int xfrm4_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
 	    (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
 		goto out;
 
-	iph = ip_hdr(skb);
-	if (iph->protocol == IPPROTO_IPIP) {
-		if (x->props.flags & XFRM_STATE_DECAP_DSCP)
-			ipv4_copy_dscp(ipv4_get_dsfield(iph), ipip_hdr(skb));
-		if (!(x->props.flags & XFRM_STATE_NOECN))
-			ipip_ecn_decapsulate(skb);
-	}
-#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
-	else {
-		if (!(x->props.flags & XFRM_STATE_NOECN))
-			ipip6_ecn_decapsulate(iph, skb);
-		skb->protocol = htons(ETH_P_IPV6);
-	}
-#endif
+	if (x->props.flags & XFRM_STATE_DECAP_DSCP)
+		ipv4_copy_dscp(XFRM_MODE_SKB_CB(skb)->tos, ipip_hdr(skb));
+	if (!(x->props.flags & XFRM_STATE_NOECN))
+		ipip_ecn_decapsulate(skb);
+
 	old_mac = skb_mac_header(skb);
 	skb_set_mac_header(skb, -skb->mac_len);
 	memmove(skb_mac_header(skb), old_mac, skb->mac_len);
@@ -119,7 +94,8 @@ out:
 }
 
 static struct xfrm_mode xfrm4_tunnel_mode = {
-	.input = xfrm4_tunnel_input,
+	.input2 = xfrm4_tunnel_input,
+	.input = xfrm_prepare_input,
 	.output2 = xfrm4_tunnel_output,
 	.output = xfrm4_prepare_output,
 	.owner = THIS_MODULE,