From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Ahern <dsa@cumulusnetworks.com>
Subject: Re: [PATCH v7 0/6] Add eBPF hooks for cgroups
Date: Fri, 28 Oct 2016 09:00:51 -0600
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To: Pablo Neira Ayuso <pablo@netfilter.org>, Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Daniel Mack <daniel@zonque.org>, htejun@fb.com, daniel@iogearbox.net, ast@fb.com, davem@davemloft.net, kafai@fb.com, fw@strlen.de, harald@redhat.com, netdev@vger.kernel.org, sargun@sargun.me, cgroups@vger.kernel.org

On 10/28/16 5:28 AM, Pablo Neira Ayuso wrote:
> I saw those, I would really like to have a closer look at David
> Ahern's usecase since that skb iif mangling looks kludgy to me, and
> given this is exposing a new helper for general use, not only vrf, it
> would be good to make sure helpers provide something useful for
> everyone. So that new helper is questionable at this stage IMO. I'm
> concerned that people may start using bpf as the adhesive tape to glue
> things to solve probably design problems.

It's changing sk_bound_dev_if on a socket when the socket is created, not skb iif. I explain the need in the cover letter. I have also explained the use case in the other attempts to solve this problem -- a stand alone l3mdev cgroup and adding a default setting to the task struct.