[IPSEC] xfrm: Abstract out encapsulation modes

This patch adds the structure xfrm_mode.  It is meant to represent
the operations carried out by transport/tunnel modes.

By doing this we allow additional encapsulation modes to be added
without clogging up the xfrm_input/xfrm_output paths.

Candidate modes include 4-to-6 tunnel mode, 6-to-4 tunnel mode, and
BEET modes.

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

1 files changed, 2 insertions, 26 deletions

diff --git a/net/ipv4/xfrm4_input.c b/net/ipv4/xfrm4_input.c
index 3e174c8..817ed84 100644
--- a/net/ipv4/xfrm4_input.c
+++ b/net/ipv4/xfrm4_input.c
@@ -13,7 +13,6 @@
 #include <linux/string.h>
 #include <linux/netfilter.h>
 #include <linux/netfilter_ipv4.h>
-#include <net/inet_ecn.h>
 #include <net/ip.h>
 #include <net/xfrm.h>
 
@@ -24,15 +23,6 @@ int xfrm4_rcv(struct sk_buff *skb)
 
 EXPORT_SYMBOL(xfrm4_rcv);
 
-static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
-{
-	struct iphdr *outer_iph = skb->nh.iph;
-	struct iphdr *inner_iph = skb->h.ipiph;
-
-	if (INET_ECN_is_ce(outer_iph->tos))
-		IP_ECN_set_ce(inner_iph);
-}
-
 static int xfrm4_parse_spi(struct sk_buff *skb, u8 nexthdr, u32 *spi, u32 *seq)
 {
 	switch (nexthdr) {
@@ -113,24 +103,10 @@ int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type)
 
 		xfrm_vec[xfrm_nr++] = x;
 
-		iph = skb->nh.iph;
+		if (x->mode->input(x, skb))
+			goto drop;
 
 		if (x->props.mode) {
-			if (iph->protocol != IPPROTO_IPIP)
-				goto drop;
-			if (!pskb_may_pull(skb, sizeof(struct iphdr)))
-				goto drop;
-			if (skb_cloned(skb) &&
-			    pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
-				goto drop;
-			if (x->props.flags & XFRM_STATE_DECAP_DSCP)
-				ipv4_copy_dscp(iph, skb->h.ipiph);
-			if (!(x->props.flags & XFRM_STATE_NOECN))
-				ipip_ecn_decapsulate(skb);
-			skb->mac.raw = memmove(skb->data - skb->mac_len,
-					       skb->mac.raw, skb->mac_len);
-			skb->nh.raw = skb->data;
-			memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
 			decaps = 1;
 			break;
 		}