[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, 7 deletions

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 8206025d8e46..ae62054a9fc4 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -996,13 +996,6 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
                         struct sec_decap_state *xvec = &(skb->sp->x[i]);
                         if (!xfrm_selector_match(&xvec->xvec->sel, &fl, family))
                                 return 0;
-
-                        /* If there is a post_input processor, try running it */
-                        if (xvec->xvec->type->post_input &&
-                            (xvec->xvec->type->post_input)(xvec->xvec,
-                                                           &(xvec->decap),
-                                                           skb) != 0)
-                                return 0;
                 }
         }