ACK: [PATCH] dev_forward_skb: do not scrub skb mark within the same name space

[Kleber Souza]

On 29.07.21 14:51, Tim Gardner wrote:
> From: Nicolas Dichtel <nicolas.dichtel at 6wind.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1935040
> 
> The goal is to keep the mark during a bpf_redirect(), like it is done for
> legacy encapsulation / decapsulation, when there is no x-netns.
> This was initially done in commit 213dd74aee76 ("skbuff: Do not scrub skb
> mark within the same name space").
> 
> When the call to skb_scrub_packet() was added in dev_forward_skb() (commit
> 8b27f27797ca ("skb: allow skb_scrub_packet() to be used by tunnels")), the
> second argument (xnet) was set to true to force a call to skb_orphan(). At
> this time, the mark was always cleanned up by skb_scrub_packet(), whatever
> xnet value was.
> This call to skb_orphan() was removed later in commit
> 9c4c325252c5 ("skbuff: preserve sock reference when scrubbing the skb.").
> But this 'true' stayed here without any real reason.
> 
> Let's correctly set xnet in ____dev_forward_skb(), this function has access
> to the previous interface and to the new interface.
> 
> Signed-off-by: Nicolas Dichtel <nicolas.dichtel at 6wind.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> (cherry picked from commit ff70202b2d1ad522275c6aadc8c53519b6a22c57)
> Signed-off-by: Tim Gardner <tim.gardner at canonical.com>

Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>

Thanks

> ---
>   include/linux/netdevice.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 11a52f2fa35de..edd3806fe944f 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -3750,7 +3750,7 @@ static __always_inline int ____dev_forward_skb(struct net_device *dev,
>   		return NET_RX_DROP;
>   	}
>   
> -	skb_scrub_packet(skb, true);
> +	skb_scrub_packet(skb, !net_eq(dev_net(dev), dev_net(skb->dev)));
>   	skb->priority = 0;
>   	return 0;
>   }
>