netdev - Re: [PATCH] net: gre: don't pull skb if dealing with icmp message

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Message-ID: <52DC7DE4.1050108@cn.fujitsu.com>
Date:	Mon, 20 Jan 2014 09:37:40 +0800
From:	Duan Jiong <duanj.fnst@...fujitsu.com>
To:	Pravin Shelar <pshelar@...ira.com>
CC:	David Miller <davem@...emloft.net>,
	Daniel Borkmann <dborkman@...hat.com>,
	netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] net: gre: don't pull skb if dealing with icmp message

于 2014年01月20日 05:08, Pravin Shelar 写道:
> On Sun, Jan 19, 2014 at 12:35 AM, Duan Jiong <duanj.fnst@...fujitsu.com> wrote:
>>
>> When dealing with icmp messages, the skb->data points the
>> ip header that triggered the sending of the icmp message.
>>
>> In gre_cisco_err(), the parse_gre_header() is called, and the
>> iptunnel_pull_header() is called to pull the skb at the end of
>> the parse_gre_header(). Unfortunately, the ipgre_err still needs
>> the skb->data points the ip header following the icmp layer,
>> and those ip addresses in ip header will be used to look up
>> tunnel by ip_tunnel_lookup().
>>
> This looks like bug.
> Can you use ip_hdr() rather than skb->data in ipgre_err().
> Same is done in ipgre_rcv().

That's maybe not a good idea. The ip_hdr() will the return the outmost
ip header, but we need inner ip header following the icmp layer.

Thanks,
  Duan

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