Re: [PATCH net-next v5] ipv6: add `force_forwarding` sysctl to enable per-interface forwarding

[Nicolas Dichtel]

Le 07/07/2025 à 11:43, Gabriel Goller a écrit :
> It is currently impossible to enable ipv6 forwarding on a per-interface
> basis like in ipv4. To enable forwarding on an ipv6 interface we need to
> enable it on all interfaces and disable it on the other interfaces using
> a netfilter rule. This is especially cumbersome if you have lots of
> interface and only want to enable forwarding on a few. According to the
> sysctl docs [0] the `net.ipv6.conf.all.forwarding` enables forwarding
> for all interfaces, while the interface-specific
> `net.ipv6.conf.<interface>.forwarding` configures the interface
> Host/Router configuration.
> 
> Introduce a new sysctl flag `force_forwarding`, which can be set on every
> interface. The ip6_forwarding function will then check if the global
> forwarding flag OR the force_forwarding flag is active and forward the
> packet.
> 
> To preserver backwards-compatibility reset the flag (on all interfaces)
> to 0 if the net.ipv6.conf.all.forwarding flag is set to 0.
> 
> Add a short selftest that checks if a packet gets forwarded with and
> without `force_forwarding`.
> 
> [0]: https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt
> 
> Signed-off-by: Gabriel Goller <g.goller@xxxxxxxxxxx>

Acked-by: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>