From mboxrd@z Thu Jan  1 00:00:00 1970
From: Changli Gao <xiaosuo@gmail.com>
Subject: Re: [PATCH] ip6tables: use skb->len for accounting
Date: Fri, 23 Jul 2010 14:38:20 +0800
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Cc: Patrick McHardy <kaber@trash.net>,
	"David S. Miller" <davem@davemloft.net>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	"Pekka Savola (ipv6)" <pekkas@netcore.fi>,
	James Morris <jmorris@namei.org>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	netfilter-devel@vger.kernel.org, netdev@vger.kernel.org
To: Jan Engelhardt <jengelh@medozas.de>
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On Fri, Jul 23, 2010 at 2:16 PM, Jan Engelhardt <jengelh@medozas.de> wrote:
>
>
> I wonder how this fares with trailing padding or data, like, when
> you have a standard v4/v6 packet created in a raw socket, and append
> a bunch of \0s to it.
>
>

For the packets received, ip_rcv, ipv6_rcv and bridge all call
pskb_trim_rcsum before feeding them to netfilter. The raw packets are
sent via dev_queue_xmit(), and they don't pass through the output path
of netfilter. One case, maybe the queued packets mangled "wrongly" in
userspace are reinjected, however, we can't prevent a user from
changing the payload_len wrongly.

-- 
Regards,
Changli Gao(xiaosuo@gmail.com)