netdev - Re: [PATCH v2 net-next 2/2] vrf: run conntrack only in context of lower/physdev for locally generated packets

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Date:   Mon, 25 Oct 2021 08:25:16 -0600
From:   David Ahern <dsahern@...il.com>
To:     Florian Westphal <fw@...len.de>, netdev@...r.kernel.org
Cc:     netfilter-devel@...r.kernel.org, lschlesinger@...venets.com,
        dsahern@...nel.org, pablo@...filter.org, crosser@...rage.org
Subject: Re: [PATCH v2 net-next 2/2] vrf: run conntrack only in context of
 lower/physdev for locally generated packets

On 10/25/21 8:14 AM, Florian Westphal wrote:
> The VRF driver invokes netfilter for output+postrouting hooks so that users
> can create rules that check for 'oif $vrf' rather than lower device name.
> 
> This is a problem when NAT rules are configured.
> 
> To avoid any conntrack involvement in round 1, tag skbs as 'untracked'
> to prevent conntrack from picking them up.
> 
> This gets cleared before the packet gets handed to the ip stack so
> conntrack will be active on the second iteration.
> 
> One remaining issue is that a rule like
> 
>   output ... oif $vrfname notrack
> 
> won't propagate to the second round because we can't tell
> 'notrack set via ruleset' and 'notrack set by vrf driver' apart.
> However, this isn't a regression: the 'notrack' removal happens
> instead of unconditional nf_reset_ct().
> I'd also like to avoid leaking more vrf specific conditionals into the
> netfilter infra.
> 
> For ingress, conntrack has already been done before the packet makes it
> to the vrf driver, with this patch egress does connection tracking with
> lower/physical device as well.
> 
> Signed-off-by: Florian Westphal <fw@...len.de>
> ---
>  drivers/net/vrf.c | 28 ++++++++++++++++++++++++----
>  1 file changed, 24 insertions(+), 4 deletions(-)
> 

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