On Wed, Aug 23, 2023 at 03:41:02PM +0200, Nicolas Dichtel wrote:
> The goal is to support a bpf_redirect() from an ethernet device (ingress)
> to a ppp device (egress).
> The l2 header is added automatically by the ppp driver, thus the ethernet
> header should be removed.
Reviewed-by: Guillaume Nault <gnault@xxxxxxxxxx>
> CC: stable@xxxxxxxxxxxxxxx
> Fixes: 27b29f63058d ("bpf: add bpf_redirect() helper")
> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
> Tested-by: Siwar Zitouni <siwar.zitouni@xxxxxxxxx>
> ---
>
> v2 -> v3:
> - add a comment in the code
> - rework the commit log
>
> v1 -> v2:
> - I forgot the 'Tested-by' tag in the v1 :/
>
> include/linux/if_arp.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/include/linux/if_arp.h b/include/linux/if_arp.h
> index 1ed52441972f..10a1e81434cb 100644
> --- a/include/linux/if_arp.h
> +++ b/include/linux/if_arp.h
> @@ -53,6 +53,10 @@ static inline bool dev_is_mac_header_xmit(const struct net_device *dev)
> case ARPHRD_NONE:
> case ARPHRD_RAWIP:
> case ARPHRD_PIMREG:
> + /* PPP adds its l2 header automatically in ppp_start_xmit().
> + * This makes it look like an l3 device to __bpf_redirect() and tcf_mirred_init().
> + */
> + case ARPHRD_PPP:
> return false;
> default:
> return true;
> --
> 2.39.2
>
