netdev - Re: [PATCH] net: ipv6 bind to device issue

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Message-ID: <20100420154239.GC5711@jolsa.lab.eng.brq.redhat.com>
Date:	Tue, 20 Apr 2010 17:42:39 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	davem@...emloft.net, kuznet@....inr.ac.ru, pekkas@...core.fi,
	jmorris@...ei.org, yoshfuji@...ux-ipv6.org, kaber@...sh.net,
	eric.dumazet@...il.com
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH] net: ipv6 bind to device issue

On Tue, Apr 20, 2010 at 02:46:12PM +0200, Jiri Olsa wrote:
> hi,
> 
> The issue raises when having 2 NICs both assigned the same
> IPv6 global address.
> 
> If a sender binds to a particular NIC (SO_BINDTODEVICE),
> the outgoing traffic is being sent via the first found.
> The bonded device is thus not taken into an account during the
> routing.
> 
> 
> From the ip6_route_output function:
> 
> If the binding address is multicast, linklocal or loopback,
> the RT6_LOOKUP_F_IFACE bit is set, but not for global address.
> 
> So binding global address will neglect SO_BINDTODEVICE-binded device,
> because the fib6_rule_lookup function path won't check for the
> flowi::oif field and take first route that fits.
> 
> Following patch should handle the issue.
> 
> wbr,
> jirka
> 
> 
> Signed-off-by: Jiri Olsa <jolsa@...hat.com>
Signed-off-by: Scott Otto <scott.otto@...atel-lucent.com>

> ---
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index c2438e8..7bf7717 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -815,7 +815,7 @@ struct dst_entry * ip6_route_output(struct net *net, struct sock *sk,
>  {
>  	int flags = 0;
>  
> -	if (rt6_need_strict(&fl->fl6_dst))
> +	if (rt6_need_strict(&fl->fl6_dst) || fl->oif)
>  		flags |= RT6_LOOKUP_F_IFACE;
>  
>  	if (!ipv6_addr_any(&fl->fl6_src))
--
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