netdev - Re: [PATCH] xfrm: Accept ESP packets regardless of UDP encapsulation mode

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Date:	Thu, 18 Dec 2008 14:47:26 +1100
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	martin@...ongswan.org (Martin Willi)
Cc:	davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH] xfrm: Accept ESP packets regardless of UDP encapsulation  mode

Martin Willi <martin@...ongswan.org> wrote:
> An IPsec node speaking IKEv2 MUST accept incoming UDP encapsulated
> ESP packets, even if no NAT situation is detected. This is important
> if MOBIKE is in use. Some implementation keep the encapsulation
> mode if they move out of a NAT situation.
> 
> diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
> index b4a1317..65bcf09 100644
> --- a/net/xfrm/xfrm_input.c
> +++ b/net/xfrm/xfrm_input.c
> @@ -167,11 +167,6 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
>                        goto drop_unlock;
>                }
> 
> -               if ((x->encap ? x->encap->encap_type : 0) != encap_type) {
> -                       XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEMISMATCH);
> -                       goto drop_unlock;
> -               }

This can't work as ESP relies on this check.  Now that it's gone
ESP may touch a UDP header which doesn't exist.

What exactly are you trying to achieve?

Thanks,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
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