netdev - Re: IPsec replay sequence number overflow behavior? (RFC4303 section 3.3.3)

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Date:	Sun, 9 Dec 2007 09:37:56 -0500
From:	Paul Moore <paul.moore@...com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	netdev@...r.kernel.org, latten@...ibm.com
Subject: Re: IPsec replay sequence number overflow behavior? (RFC4303 section 3.3.3)

On Saturday 08 December 2007 9:13:48 pm Herbert Xu wrote:
> Paul Moore <paul.moore@...com> wrote:
> > If it is a bug, I think the basic fix should be pretty simple, changing
> > the above xfrm_output() code to the following:
> >
> >   if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
> >           XFRM_SKB_CB(skb)->seq = ++x->replay.oseq;
> > +          if (x->replay.oseq == 0)
> > +                  goto error;
>
> Yes we need this check.
>
> However please add an unlikely around it since it's a 1-in-4
> billion event :)

 :)

Thanks for clearing that up, I'll send a patch this week; complete with an 
unlikely (similar to the RFC quality IPsec audit patch I sent on Friday) and 
a decrement to the sequence counter in case of rollover.

-- 
paul moore
linux security @ hp
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