From: Herbert Xu <herbert@gondor.hengli.com.au>
To: Changli Gao <xiaosuo@gmail.com>
Cc: Jamal Hadi Salim <hadi@cyberus.ca>,
"David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Patrick McHardy <kaber@trash.net>
Subject: Re: [PATCH] act_nat: the checksum of ICMP doesn't have pseudo header
Date: Fri, 30 Jul 2010 22:30:16 +0800 [thread overview]
Message-ID: <20100730143016.GA10543@gondor.apana.org.au> (raw)
In-Reply-To: <AANLkTimKXsgmOSVmw-cP6Zw6UoK5CSshK38Oo5tLuAeA@mail.gmail.com>
On Fri, Jul 30, 2010 at 10:16:05PM +0800, Changli Gao wrote:
>
> I know we need to update the ICMP checksum if we alter the payload(the
> inner IP header here) of ICMP. But I doubt if the update is really
> necessary if the checksum is partial, as the checksum will be done
> later(by ether skb_checksum_help() or NIC hardware). In fact, as there
> isn't any pseudo header, the icmph->checksum should be always ZERO,
> otherwise skb_checksum_help() or NIC will give the wrong checksums,
> when the checksum is partial.
Actually you are right. I suppose the only reason this has never
shown up is because CHEKSUM_PARTIAL doesn't usually occur with
forwarded packets.
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Thanks,
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
next prev parent reply other threads:[~2010-07-30 14:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-30 0:04 Changli Gao
2010-07-30 9:09 ` Herbert Xu
2010-07-30 10:10 ` Changli Gao
2010-07-30 10:24 ` Herbert Xu
2010-07-30 14:16 ` Changli Gao
2010-07-30 14:30 ` Herbert Xu [this message]
2010-08-01 5:05 ` David Miller
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