On Thu, Aug 03, 2006 at 11:29:41AM +0200, Patrick McHardy wrote:
> >>+u_int16_t nf_proto_csum_update(struct sk_buff *skb,
> >>+ u_int32_t oldval, u_int32_t newval,
> >>+ u_int16_t csum, int pseudohdr)
> >>+{
> >>+ if (skb->ip_summed != CHECKSUM_PARTIAL) {
> >>+ csum = nf_csum_update(oldval, newval, csum);
> >>+ if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
> >
> >
> > Shouldn't that be !pseudohdr?
>
> No, if the changed data is part of the pseudo-hdr, we need to update
> skb->csum so the skb passes later checksum checks.
Are you sure? If ip_summed is CHECKSUM_COMPLETE then skb->csum is the
checksum of the payload *without* the pseudo header.
> > This is a 32-bit quantity so nf_csum_update should eat a 32-bit quantity
> > as well. Also, this checksum is not inverted so you need
> >
> > skb->csum = ~nf_csum_update(oldval, newval, ~skb->csum);
>
> I'll change it to 32-bit and try the inversion, but it works fine this
> way.
It'll break for e1000 at least since it puts the checksum into the
high 16 bits of skb->csum (on i386).
Cheers,
--
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