[IPSEC]: Kill post_input hook and do NAT-T in esp_input directly

The only reason post_input exists at all is that it gives us the
potential to adjust the checksums incrementally in future which
we ought to do.

However, after thinking about it for a bit we can adjust the
checksums without using this post_input stuff at all.  The crucial
point is that only the inner-most NAT-T SA needs to be considered
when adjusting checksums.  What's more, the checksum adjustment
comes down to a single u32 due to the linearity of IP checksums.

We just happen to have a spare u32 lying around in our skb structure :)
When ip_summed is set to CHECKSUM_NONE on input, the value of skb->csum
is currently unused.  All we have to do is to make that the checksum
adjustment and voila, there goes all the post_input and decap structures!

I've left in the decap data structures for now since it's intricately
woven into the sec_path stuff.  We can kill them later too.

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

1 files changed, 0 insertions, 1 deletions

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 004e645f3e18..8d362c49b8a9 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -233,7 +233,6 @@ struct xfrm_type
         int                     (*init_state)(struct xfrm_state *x);
         void                    (*destructor)(struct xfrm_state *);
         int                     (*input)(struct xfrm_state *, struct xfrm_decap_state *, struct sk_buff *skb);
-        int                     (*post_input)(struct xfrm_state *, struct xfrm_decap_state *, struct sk_buff *skb);
         int                     (*output)(struct xfrm_state *, struct sk_buff *pskb);
         /* Estimate maximal size of result of transformation of a dgram */
         u32                     (*get_max_size)(struct xfrm_state *, int size);