Subject: Re: [PATCH] resume oif rule match l3mdev in fib_lookup

From: Ido Schimmel <[email-masked]>
Date: Mon, 14 Apr 2025 10:17:31 +0300

On Sat, Apr 12, 2025 at 09:19:10PM +0800, hanhuihui wrote:
> flowi_oif will be reset if flowi_oif set to a l3mdev (e.g., VRF) device.
> This causes the oif rule to fail to match the l3mdev device in fib_lookup.
> Let's get back to previous behavior.
> 
> Fixes: 40867d74c374 ("net: Add l3mdev index to flow struct and avoid oif reset for port devices")
> Signed-off-by: hanhuihui [email-masked]
> ---
>  net/core/fib_rules.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
> index 4bc64d9..3c2a2db 100644
> --- a/net/core/fib_rules.c
> +++ b/net/core/fib_rules.c
> @@ -268,7 +268,7 @@ static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
>  		goto out;
>  
>  	oifindex = READ_ONCE(rule->oifindex);
> -	if (oifindex && (oifindex != fl->flowi_oif))
> +	if (oifindex && (oifindex != (fl->flowi_l3mdev ? : fl->flowi_oif)))

This will prevent us from matching on the output device when the device
is enslaved to a VRF. We should try to match on L3 domain only if the
FIB rule matches on a VRF device. I will try to send a fix today (wasn't
feeling well in the last few days).

>  		goto out;
>  
>  	if ((rule->mark ^ fl->flowi_mark) & rule->mark_mask)
> -- 
> 2.27.0
>