netdev - Re: [PATCH net v2] ipv6: enforce egress device match in per table nexthop lookups

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Date:	Thu, 23 Jun 2016 08:20:20 -0600
From:	David Ahern <dsa@...ulusnetworks.com>
To:	Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org
Cc:	"David S. Miller" <davem@...emloft.net>,
	Beniamino Galvani <bgalvani@...hat.com>
Subject: Re: [PATCH net v2] ipv6: enforce egress device match in per table
 nexthop lookups

On 6/23/16 7:25 AM, Paolo Abeni wrote:
> with the commit 8c14586fc320 ("net: ipv6: Use passed in table for
> nexthop lookups"), net hop lookup is first performed on route creation
> in the passed-in table.
> However device match is not enforced in table lookup, so the found
> route can be later discarded due to egress device mismatch and no
> global lookup will be performed.
> This cause the following to fail:
>
> ip link add dummy1 type dummy
> ip link add dummy2 type dummy
> ip link set dummy1 up
> ip link set dummy2 up
> ip route add 2001:db8:8086::/48 dev dummy1 metric 20
> ip route add 2001:db8:d34d::/64 via 2001:db8:8086::2 dev dummy1 metric 20
> ip route add 2001:db8:8086::/48 dev dummy2 metric 21
> ip route add 2001:db8:d34d::/64 via 2001:db8:8086::2 dev dummy2 metric 21
> RTNETLINK answers: No route to host
>
> This change fixes the issue enforcing device lookup in
> ip6_nh_lookup_table()
>
> v1->v2: updated commit message title
>
> Fixes: 8c14586fc320 ("net: ipv6: Use passed in table for nexthop lookups")
> Reported-and-tested-by: Beniamino Galvani <bgalvani@...hat.com>
> Signed-off-by: Paolo Abeni <pabeni@...hat.com>
> ---
>  net/ipv6/route.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 969913d..520b788 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -1782,7 +1782,7 @@ static struct rt6_info *ip6_nh_lookup_table(struct net *net,
>  	};
>  	struct fib6_table *table;
>  	struct rt6_info *rt;
> -	int flags = 0;
> +	int flags = RT6_LOOKUP_F_IFACE;
>
>  	table = fib6_get_table(net, cfg->fc_table);
>  	if (!table)
>

Acked-by: David Ahern <dsa@...ulusnetworks.com>