From: Duan Jiong <duanj.fnst@cn•fujitsu.com>
To: David Miller <davem@davemloft•net>
Cc: djduanjiong@gmail•com, netdev@vger•kernel.org
Subject: Re: [PATCH v2] ip6tnl: do route updating for redirect in ip6_tnl_err()
Date: Fri, 20 Sep 2013 18:43:08 +0800 [thread overview]
Message-ID: <523C26BC.5050408@cn.fujitsu.com> (raw)
In-Reply-To: <20130919.140213.417316271045370155.davem@davemloft.net>
于 2013年09月20日 02:02, David Miller 写道:
> From: Duan Jiong <djduanjiong@gmail•com>
> Date: Tue, 17 Sep 2013 20:27:57 -0700
>
>> After the ip6_tnl_err() is called, the rel_msg is assigned to
>> 0, and the ip4ip6_err() will return directly, the instruction
>> below will not be executed.
>>
>> In rfc2473, we can know that the tunnel ICMP redirect message
>> should not be reported to the source of the original packet,
>> so we can handle it in ip6_tnl_err().
>>
>> Signed-off-by: Duan Jiong <duanj.fnst@cn•fujitsu.com>
>
> I do not think this change is correct.
>
>> @@ -576,9 +579,6 @@ ip4ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
>> rel_type = ICMP_DEST_UNREACH;
>> rel_code = ICMP_FRAG_NEEDED;
>> break;
>> - case NDISC_REDIRECT:
>> - rel_type = ICMP_REDIRECT;
>> - rel_code = ICMP_REDIR_HOST;
>> default:
>> return 0;
>> }
>
> The bug is a missing "break;" statement for this case, and:
You can read the ip6_tnl_err(). when the message is NDISC_REDIRECT, the
rel_msg is assigned to 0, then
561 if (rel_msg == 0)
562 return 0;
the function ip4ip6_err() return directly. so even though you add "break;"
statement for this case, the redirect message will not be handled.
>
>> @@ -637,8 +637,6 @@ ip4ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
>>
>> skb_dst(skb2)->ops->update_pmtu(skb_dst(skb2), NULL, skb2, rel_info);
>> }
>> - if (rel_type == ICMP_REDIRECT)
>> - skb_dst(skb2)->ops->redirect(skb_dst(skb2), NULL, skb2);
>>
>
> We absolutely must run the ipv4 dst_ops redirect handler here so you must
> keep this code around as well.
>
Because the Redirect Message is sent to tunnel entry-point, so the target address in
Redirect ICMPv6 Message is an ipv6 address, then we could not run the ipv4 dst_ops
redirect handler here.
Thanks,
Duan
> The only change you need to make is to add the missing break;
> statement to ip4ip6_err() and then also add appropriate NDISC_REDIRECT
> handling to ip6ip6_err().
prev parent reply other threads:[~2013-09-20 10:44 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-18 3:27 [PATCH v2] ip6tnl: do route updating for redirect in ip6_tnl_err() Duan Jiong
2013-09-19 18:02 ` David Miller
2013-09-20 10:43 ` Duan Jiong [this message]
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