netdev - Re: [PATCH v2 1/1] ipv6 : ip6mr.c : Fix can't match the IPv6 multicast packets with input net device in netfilter FORWARD chain.

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Message-ID: <1343977858.4579.11.camel@barry.localdomain>
Date:	Fri, 03 Aug 2012 15:10:58 +0800
From:	Jun Zhao <mypopydev@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	kuznet@....inr.ac.ru, jmorris@...ei.org, yoshfuji@...ux-ipv6.org,
	kaber@...sh.net, netdev@...r.kernel.org
Subject: Re: [PATCH v2 1/1] ipv6 : ip6mr.c : Fix can't match the IPv6
 multicast packets with input net device in netfilter FORWARD chain.

On Thu, 2012-08-02 at 23:43 -0700, David Miller wrote:
> From: Jun Zhao <mypopydev@...il.com>
> Date: Fri,  3 Aug 2012 14:27:51 +0800
> 
> > @@ -1960,7 +1962,7 @@ static int ip6mr_forward2(struct net *net, struct mr6_table *mrt,
> >  
> >  	IP6CB(skb)->flags |= IP6SKB_FORWARDED;
> >  
> > -	return NF_HOOK(NFPROTO_IPV6, NF_INET_FORWARD, skb, skb->dev, dev,
> > +	return NF_HOOK(NFPROTO_IPV6, NF_INET_FORWARD, skb, indev, dev,
> >  		       ip6mr_forward2_finish);
> >  
> 
> This patch has the same problem I mentioned, it means someone who is
> now matching on the VIF device will now fail to do son.
> 
> You have to understand that you simply cannot change the behavior
> here without breaking something for someone.

Hi, David:

Can you give me some more details what I break in this fix?

As my understanding, in the ip6mr_forward2(), vifi is the VIF index for
output, we can get the output device used vif->dev and record input
device before change skb->dev; then used FORWARD chain match the rules. 

Tks.

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