netdev - Re: [PATCH bpf-next] bpf: add read/write access to skb->tstamp from tc clsact progs

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Message-ID: <CALpBo+URiVUOkATDFtuyTnbX-FQVofy05Lh4tUb88+bihR+AXw@mail.gmail.com>
Date:   Wed, 21 Nov 2018 10:48:21 -0800
From:   Vlad Dumitrescu <vlad@...itrescu.ro>
To:     eric.dumazet@...il.com, alexei.starovoitov@...il.com
Cc:     Vlad Dumitrescu <vladum@...gle.com>, ast@...nel.org,
        Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org,
        edumazet@...gle.com, willemb@...gle.com
Subject: Re: [PATCH bpf-next] bpf: add read/write access to skb->tstamp from
 tc clsact progs

On Wed, Nov 21, 2018 at 5:08 AM Eric Dumazet <eric.dumazet@...il.com> wrote:
>
>
>
> On 11/20/2018 06:40 PM, Alexei Starovoitov wrote:
>
> >
> > looks good to me.
> >
> > Any particular reason you decided to disable it for cg_skb ?
> > It seems to me the same EDT approach will work from
> > cgroup-bpf skb hooks just as well and then we can have neat
> > way of controlling traffic per-container instead of tc-clsbpf global.
> > If you're already on cgroup v2 it will save you a lot of classifier
> > cycles, since you'd be able to group apps by cgroup
> > instead of relying on ip only.
>
> Vlad first wrote a complete version, but we felt explaining the _why_
> was probably harder.
>
> No particular reason, other than having to write more tests perhaps.

This sounds reasonable to me. I can prepare a v2.

Any concerns regarding capabilities? For example data and data_end are
only available to CAP_SYS_ADMIN. Note that enforcement of this would
be done by a global component later in the pipeline (e.g., FQ qdisc).

Any opinions on sk_filter, lwt, and sk_skb before I send v2?