[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, 9 insertions, 22 deletions

diff --git a/net/ipv6/xfrm6_mode_tunnel.c b/net/ipv6/xfrm6_mode_tunnel.c
index d45ce5d44197..f7d0d6612650 100644
--- a/net/ipv6/xfrm6_mode_tunnel.c
+++ b/net/ipv6/xfrm6_mode_tunnel.c
@@ -25,12 +25,6 @@ static inline void ipip6_ecn_decapsulate(struct sk_buff *skb)
                 IP6_ECN_set_ce(inner_iph);
 }
 
-static inline void ip6ip_ecn_decapsulate(struct sk_buff *skb)
-{
-        if (INET_ECN_is_ce(ipv6_get_dsfield(ipv6_hdr(skb))))
-                        IP_ECN_set_ce(ipip_hdr(skb));
-}
-
 /* Add encapsulation header.
  *
  * The top IP header will be constructed per RFC 2401.
@@ -68,10 +62,8 @@ static int xfrm6_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
 {
         int err = -EINVAL;
         const unsigned char *old_mac;
-        const unsigned char *nh = skb_network_header(skb);
 
-        if (nh[IP6CB(skb)->nhoff] != IPPROTO_IPV6 &&
-            nh[IP6CB(skb)->nhoff] != IPPROTO_IPIP)
+        if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPV6)
                 goto out;
         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
                 goto out;
@@ -80,18 +72,12 @@ static int xfrm6_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
             (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
                 goto out;
 
-        nh = skb_network_header(skb);
-        if (nh[IP6CB(skb)->nhoff] == IPPROTO_IPV6) {
-                if (x->props.flags & XFRM_STATE_DECAP_DSCP)
-                        ipv6_copy_dscp(ipv6_get_dsfield(ipv6_hdr(skb)),
-                                       ipipv6_hdr(skb));
-                if (!(x->props.flags & XFRM_STATE_NOECN))
-                        ipip6_ecn_decapsulate(skb);
-        } else {
-                if (!(x->props.flags & XFRM_STATE_NOECN))
-                        ip6ip_ecn_decapsulate(skb);
-                skb->protocol = htons(ETH_P_IP);
-        }
+        if (x->props.flags & XFRM_STATE_DECAP_DSCP)
+                ipv6_copy_dscp(ipv6_get_dsfield(ipv6_hdr(skb)),
+                               ipipv6_hdr(skb));
+        if (!(x->props.flags & XFRM_STATE_NOECN))
+                ipip6_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);
@@ -103,7 +89,8 @@ out:
 }
 
 static struct xfrm_mode xfrm6_tunnel_mode = {
-        .input = xfrm6_tunnel_input,
+        .input2 = xfrm6_tunnel_input,
+        .input = xfrm_prepare_input,
         .output2 = xfrm6_tunnel_output,
         .output = xfrm6_prepare_output,
         .owner = THIS_MODULE,