From: Ang Way Chuang <wcang@sfc•wide.ad.jp>
To: "Yan, Zheng " <yanzheng@21cn•com>
Cc: "Eric Dumazet" <eric.dumazet@gmail•com>,
netdev@vger•kernel.org, "Linus Lüssing" <linus.luessing@web•de>,
"Herbert Xu" <herbert@gondor•apana.org.au>
Subject: Re: IPv6 multicast snooping behaviour on 2.6.39-rc2 and later
Date: Wed, 24 Aug 2011 16:38:39 +0900 [thread overview]
Message-ID: <4E54AA7F.80107@sfc.wide.ad.jp> (raw)
In-Reply-To: <CAAM7YAmht5FFTTFHrDUXAXHD5h5gzn1GrtEbHkQfbaoCwccG0w@mail.gmail.com>
Thanks Zheng Yan. Your patch works as well. I trust others' code more than mine,
so please ignore the patch that I sent earlier.
On 24/08/11 16:04, Yan, Zheng wrote:
> On Wed, Aug 24, 2011 at 1:24 AM, Ang Way Chuang <wcang@sfc•wide.ad.jp> wrote:
>> This is what I found so far from debugging.
>>
>> The packet is not forwarded due to the failed checksum at
>> br_multicast.c:1533
>>
>> case CHECKSUM_NONE:
>> skb2->csum = 0;
>> if (skb_checksum_complete(skb2))
>> goto out;
>> }
>>
>> Contrary to description of commit ff9a57a6, when the patch of commit
>> ff9a57a6 is applied,
>> pskb_trim_rcsum is never called at all on my testbed. When commit ff9a57a6
>> is reverted,
>> pskb_trim_rcsum will be called. The difference is:
>>
>> with commit ff9a57a6,
>> pskb_trim_rcsum is never called, br_multicast_ipv6_rcv returns -EINVAL
>> which causes
>> br_handle_frame_finish to drop the packet
>>
>> without commit ff9a57a6,
>> pskb_trim_rcsum is called overwriting err with 0. br_multicast_ipv6_rcv
>> still fails on the
>> same line (skb_checksum_complete). But the difference is err is set to 0
>> this time. Thereby,
>> allowing the packet to be forwarded.
>>
>> Anyway, I don't think the behaviour is correct with or without commit
>> ff9a57a6
>>
>>
> Looks like a checksum calculation bug. Please try below patch, Thanks.
>
> ---
> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
> index 2d85ca7..22d2d1a 100644
> --- a/net/bridge/br_multicast.c
> +++ b/net/bridge/br_multicast.c
> @@ -1520,16 +1520,23 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br,
> err = pskb_trim_rcsum(skb2, len);
> if (err)
> goto out;
> + err = -EINVAL;
> }
>
> + ip6h = ipv6_hdr(skb2);
> +
> switch (skb2->ip_summed) {
> case CHECKSUM_COMPLETE:
> - if (!csum_fold(skb2->csum))
> + if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, skb2->len,
> + IPPROTO_ICMPV6, skb2->csum))
> break;
> /*FALLTHROUGH*/
> case CHECKSUM_NONE:
> - skb2->csum = 0;
> - if (skb_checksum_complete(skb2))
> + skb2->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
> + &ip6h->daddr,
> + skb2->len,
> + IPPROTO_ICMPV6, 0));
> + if (__skb_checksum_complete(skb2))
> goto out;
> }
>
> ---
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
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>
prev parent reply other threads:[~2011-08-24 7:38 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-23 8:41 IPv6 multicast snooping behaviour on 2.6.39-rc2 and later Ang Way Chuang
2011-08-23 9:57 ` Eric Dumazet
2011-08-23 12:31 ` Ang Way Chuang
2011-08-23 13:10 ` Eric Dumazet
2011-08-23 14:04 ` Ang Way Chuang
2011-08-23 17:24 ` Ang Way Chuang
2011-08-24 4:56 ` [PATCH] bridge: Pseudo-header required for the checksum of ICMP6 header of MLD Ang Way Chuang
2011-08-24 5:06 ` David Miller
2011-08-24 7:04 ` IPv6 multicast snooping behaviour on 2.6.39-rc2 and later Yan, Zheng
2011-08-24 7:22 ` Eric Dumazet
2011-08-24 7:38 ` Ang Way Chuang [this message]
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