netdev - Re: [PATCH bpf-next V3 4/6] bpf: make it possible to identify BPF redirected SKBs

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Date:   Fri, 9 Oct 2020 18:47:45 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Jesper Dangaard Brouer <brouer@...hat.com>, bpf@...r.kernel.org
Cc:     netdev@...r.kernel.org, Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        maze@...gle.com, lmb@...udflare.com, shaun@...era.io,
        Lorenzo Bianconi <lorenzo@...nel.org>, marek@...udflare.com,
        John Fastabend <john.fastabend@...il.com>,
        Jakub Kicinski <kuba@...nel.org>, eyal.birger@...il.com
Subject: Re: [PATCH bpf-next V3 4/6] bpf: make it possible to identify BPF
 redirected SKBs

On 10/8/20 4:09 PM, Jesper Dangaard Brouer wrote:
> This change makes it possible to identify SKBs that have been redirected
> by TC-BPF (cls_act). This is needed for a number of cases.
> 
> (1) For collaborating with driver ifb net_devices.
> (2) For avoiding starting generic-XDP prog on TC ingress redirect.
> 
> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>

Not sure if anyone actually cares about ifb devices, but my worry is that the
generic XDP vs tc interaction has been as-is for quite some time so this change
in behavior could break in the wild.