Date: Fri, 5 Nov 2004 00:17:34 +0100
From: Matthias Andree <matthias.andree@gmx.de>
To: Patrick McHardy <kaber@trash.net>
Cc: Matthias Andree <matthias.andree@gmx.de>,
       netfilter-devel@lists.netfilter.org, linux-net@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: [BK PATCH] Fix ip_conntrack_amanda data corruption bug that breaks amanda dumps
Message-ID: <20041104231734.GA30029@merlin.emma.line.org>
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	netfilter-devel@lists.netfilter.org, linux-net@vger.kernel.org,
	linux-kernel@vger.kernel.org
References: <20041104121522.GA16547@merlin.emma.line.org> <418A7B0B.7040803@trash.net>
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On Thu, 04 Nov 2004, Patrick McHardy wrote:

> Matthias Andree wrote:
> 
> >You can use "bk receive" to patch with this mail.
> >
> >BK: Parent repository is bk://linux.bkbits.net/linux-2.5
> >
> >Patch description:
> >ChangeSet@1.2427, 2004-11-04 13:00:54+01:00, matthias.andree@gmx.de
> >   Fix ip_conntrack_amanda data corruption bug that breaks amanda dumps.
> > 
> >   Fix a bug where the ip_conntrack_amanda module replaces the first LF
> >   after "CONNECT " by a NUL byte. This causes the UDP checksum to become
> >   corrupt and strips off the OPTIONS argument from the received packet,
> >   breaking amanda's sendbackup component altogether.  Replace the LF
> >   character before releasing the buffer.
> >
> The data that is changed is only a copy, the actual packet is not touched.

Why then does the application not see the packets as long as
ip_conntrack_amanda is loaded and starts seeing them again as soon as
"rmmod ip_conntrack_amanda" has completed?

And I'm not even arguing with tcpdump which may get the altered copy of the packet.

I am unaware of two things:
1. detailed packet flow and SKBs
2. internal ip_conntrack API.

I am however seeing that ip_conntrack_amanda
1. jams the application's protocol
2. modifies the packet.

So is there any evidence to support the "only a copy" theory?

-- 
Matthias Andree
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