netdev - Re: [PATCH] net: ICMPv6 packets transmitted on wrong interface if nfmark is mangled

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Message-ID: <CA+e04fgTfSYppUHZkv0DaTawHEOKA-YXiahEJwTS75ndkK1TXw@mail.gmail.com>
Date:	Thu, 6 Dec 2012 10:11:23 +0100
From:	Dries De Winter <dries.dewinter@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	pablo@...filter.org, kaber@...sh.net, netdev@...r.kernel.org,
	netfilter-devel@...r.kernel.org
Subject: Re: [PATCH] net: ICMPv6 packets transmitted on wrong interface if
 nfmark is mangled

2012/12/5 David Miller <davem@...emloft.net>:
> From: Dries De Winter <dries.dewinter@...il.com>
> Date: Wed, 5 Dec 2012 14:41:59 +0100
>
>> My "noreroute" patch will not fix this. Therefore it's indeed maybe
>> better to add a simple check to ip6_route_me_harder(): not a check for
>> ICMPv6, but a check for (ipv6_addr_type(&iph->daddr) &
>> IPV6_ADDR_LINKLOCAL) instead. What do you think?
>
> What if a packet is rewritten from a non-link-local destination address
> into a link-local one?  Or vice versa?
>
> Your test will fail in those cases.

You are saying that the decision should be based on the original
destination address rather the modified one? I would say the opposite:

- If a non-link-local destination is changed into a link-local one, it
should certainly not be rerouted because routing doesn't make much
sense for link-local destinations.

- If a link-local destination is changed into a non-link-local one,
why not reroute it according to the new destination?

If you do not agree, we can also put the check in
ip6t_local_out_hook() where the original destination is still
available.

Dries.
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