netdev - Re: [PATCH net 1/1] vrf: Revert "Reset skb conntrack connection..."

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Date:   Tue, 19 Oct 2021 20:02:29 -0600
From:   David Ahern <dsahern@...il.com>
To:     Eugene Crosser <crosser@...rage.org>, netdev@...r.kernel.org
Cc:     netfilter-devel@...r.kernel.org, David Ahern <dsahern@...il.com>,
        Florian Westphal <fw@...len.de>,
        Lahav Schlesinger <lschlesinger@...venets.com>
Subject: Re: [PATCH net 1/1] vrf: Revert "Reset skb conntrack connection..."

On 10/18/21 12:22 PM, Eugene Crosser wrote:
> This reverts commit 09e856d54bda5f288ef8437a90ab2b9b3eab83d1.
> 
> When an interface is enslaved in a VRF, prerouting conntrack hook is
> called twice: once in the context of the original input interface, and
> once in the context of the VRF interface. If no special precausions are
> taken, this leads to creation of two conntrack entries instead of one,
> and breaks SNAT.
> 
> Commit above was intended to avoid creation of extra conntrack entries
> when input interface is enslaved in a VRF. It did so by resetting
> conntrack related data associated with the skb when it enters VRF context.
> 
> However it breaks netfilter operation. Imagine a use case when conntrack
> zone must be assigned based on the original input interface, rather than
> VRF interface (that would make original interfaces indistinguishable). One
> could create netfilter rules similar to these:
> 
>         chain rawprerouting {
>                 type filter hook prerouting priority raw;
>                 iif realiface1 ct zone set 1 return
>                 iif realiface2 ct zone set 2 return
>         }
> 
> This works before the mentioned commit, but not after: zone assignment
> is "forgotten", and any subsequent NAT or filtering that is dependent
> on the conntrack zone does not work.
> 
...

> 
> Signed-off-by: Eugene Crosser <crosser@...rage.org>
> ---
>  drivers/net/vrf.c | 4 ----
>  1 file changed, 4 deletions(-)
> 

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