[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, 13 insertions, 0 deletions

diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index cb97fda1b6df..4c803f7e74e5 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -81,6 +81,19 @@ int xfrm_parse_spi(struct sk_buff *skb, u8 nexthdr, __be32 *spi, __be32 *seq)
 }
 EXPORT_SYMBOL(xfrm_parse_spi);
 
+int xfrm_prepare_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err;
+
+	err = x->outer_mode->afinfo->extract_input(x, skb);
+	if (err)
+		return err;
+
+	skb->protocol = x->inner_mode->afinfo->eth_proto;
+	return x->inner_mode->input2(x, skb);
+}
+EXPORT_SYMBOL(xfrm_prepare_input);
+
 void __init xfrm_input_init(void)
 {
 	secpath_cachep = kmem_cache_create("secpath_cache",