Subject: Re: [PATCH net-next] bpf: allow BPF programs access skb->skb_iif and skb->dev->ifindex fields

From: Daniel Borkmann <[email-masked]>
Date: Thu, 28 May 2015 21:22:34 +0200

On 05/28/2015 12:30 AM, Alexei Starovoitov wrote:
> classic BPF already exposes skb->dev->ifindex via SKF_AD_IFINDEX extension.
> Allow eBPF program to access it as well. Note that classic aborts execution
> of the program if 'skb->dev == NULL' (which is inconvenient for program
> writers), whereas eBPF returns zero in such case.

That's better, yep.

> Also expose the 'skb_iif' field, since programs triggered by redirected
> packet need to known the original interface index.
> Summary:
> __skb->ifindex         -> skb->dev->ifindex
> __skb->ingress_ifindex -> skb->skb_iif
>
> Signed-off-by: Alexei Starovoitov <[email-masked]>

Acked-by: Daniel Borkmann <[email-masked]>