netdev - Re: [PATCH net] net: vrf: determine the dst using the original ifindex for multicast

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Date:   Tue, 20 Dec 2022 11:58:26 -0700
From:   David Ahern <dsahern@...nel.org>
To:     Antoine Tenart <atenart@...nel.org>, davem@...emloft.net,
        kuba@...nel.org, pabeni@...hat.com, edumazet@...gle.com
Cc:     netdev@...r.kernel.org, Jianlin Shi <jishi@...hat.com>
Subject: Re: [PATCH net] net: vrf: determine the dst using the original
 ifindex for multicast

On 12/20/22 10:18 AM, Antoine Tenart wrote:
> Multicast packets received on an interface bound to a VRF are marked as
> belonging to the VRF and the skb device is updated to point to the VRF
> device itself. This was fine even when a route was associated to a
> device as when performing a fib table lookup 'oif' in fib6_table_lookup
> (coming from 'skb->dev->ifindex' in ip6_route_input) was set to 0 when
> FLOWI_FLAG_SKIP_NH_OIF was set.
> 
> With commit 40867d74c374 ("net: Add l3mdev index to flow struct and
> avoid oif reset for port devices") this is not longer true and multicast
> traffic is not received on the original interface.
> 
> Instead of adding back a similar check in fib6_table_lookup determine
> the dst using the original ifindex for multicast VRF traffic. To make
> things consistent across the function do the above for all strict
> packets, which was the logic before commit 6f12fa775530 ("vrf: mark skb
> for multicast or link-local as enslaved to VRF"). Note that reverting to
> this behavior should be fine as the change was about marking packets
> belonging to the VRF, not about their dst.
> 
> Fixes: 40867d74c374 ("net: Add l3mdev index to flow struct and avoid oif reset for port devices")
> Cc: David Ahern <dsahern@...nel.org>
> Reported-by: Jianlin Shi <jishi@...hat.com>
> Signed-off-by: Antoine Tenart <atenart@...nel.org>
> ---
>  drivers/net/vrf.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@...nel.org>