[Bridge] [PATCH] bridge: mcast snooping, fix IPv6 MLD checksum calculation
Linus Lüssing
linus.luessing at web.de
Sun Mar 27 00:06:45 PDT 2011
So instead of 'if (!csum_fold(skb2->csum))' it should be this?
---
if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
skb2->len, nexthdr, skb2->csum))
---
(I'm peeking a little bit at
http://lxr.linux.no/linux+*/net/ipv6/netfilter.c#L98)
Hmm, if so, then I don't know how to test and verify that now though.
Cheers, Linus
On Sun, Mar 27, 2011 at 02:37:49PM +0800, Herbert Xu wrote:
> On Sun, Mar 27, 2011 at 08:27:23AM +0200, Linus Lüssing wrote:
> > In contrast to IGMP, the MLDv1/2 message checksum needs to include an
> > IPv6 "pseudo-header" in the calculations (see RFC2710, section 3.3;
> > RFC3810, section 5.1.2).
> >
> > The multicast snooping feature of the bridge code however did not take
> > this "pseudo-header" into consideration for the checksum validation when
> > parsing a snooped IPv6 MLDv1/2 message of another host, leading to
> > possibly ignored, though valid MLDv1/2 messages. This commit shall fix
> > this issue.
> >
> > Signed-off-by: Linus Lüssing <linus.luessing at web.de>
> > ---
> > net/bridge/br_multicast.c | 5 ++++-
> > 1 files changed, 4 insertions(+), 1 deletions(-)
> >
> > diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
> > index f61eb2e..47fae4f 100644
> > --- a/net/bridge/br_multicast.c
> > +++ b/net/bridge/br_multicast.c
> > @@ -1525,7 +1525,10 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br,
> > break;
> > /*FALLTHROUGH*/
> > case CHECKSUM_NONE:
> > - skb2->csum = 0;
> > + skb2->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
> > + &ip6h->daddr,
> > + skb2->len,
> > + nexthdr, 0));
>
> You also need to include the pseudo-header for the CHECKSUM_COMPLETE
> case, before we've fallen through (which only happens if the
> hardware checksum doesn't match).
>
> Thanks,
> --
> Email: Herbert Xu <herbert at gondor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
>
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