netdev - Re: [net-next v3 0/2] eBPF seccomp filters

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Date:   Mon, 26 Feb 2018 18:01:53 -0700
From:   Tycho Andersen <tycho@...ho.ws>
To:     Kees Cook <keescook@...omium.org>
Cc:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Sargun Dhillon <sargun@...gun.me>,
        Network Development <netdev@...r.kernel.org>,
        Linux Containers <containers@...ts.linux-foundation.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andy Lutomirski <luto@...capital.net>,
        Will Drewry <wad@...omium.org>,
        Jessica Frazelle <me@...sfraz.com>, cpuguy83@...il.com,
        Tom Hromatka <tom.hromatka@...cle.com>,
        James Morris <jmorris@...ei.org>
Subject: Re: [net-next v3 0/2] eBPF seccomp filters

On Mon, Feb 26, 2018 at 03:20:15PM -0800, Kees Cook wrote:
> On Mon, Feb 26, 2018 at 3:04 PM, Alexei Starovoitov
> <alexei.starovoitov@...il.com> wrote:
> > On Mon, Feb 26, 2018 at 07:26:54AM +0000, Sargun Dhillon wrote:
> >> This patchset enables seccomp filters to be written in eBPF. Although, this
> >> [...]
> > The main statement I want to hear from seccomp maintainers before
> > proceeding any further on this that enabling eBPF in seccomp won't lead
> > to seccomp folks arguing against changes in bpf core (like verifier)
> > just because it's used by seccomp.
> > It must be spelled out in the commit log with explicit Ack.
> 
> The primary thing I'm concerned about with eBPF and seccomp is
> side-effects from eBPF programs running at syscall time. This is an
> extremely sensitive area, and I want to be sure there won't be
> feature-creep here that leads to seccomp getting into a bad state.
> 
> As long as seccomp can continue have its own verifier,

I guess these patches should introduce some additional restrictions in
kernel/seccomp.c then? Based on my reading now, it's whatever the eBPF
verifier allows.

> I *think* this will be fine, though, again I remain concerned about
> maps, etc. I'm still reviewing these patches and how they might
> provide overlap with Tycho's needs too, etc.

Yes, it's on my TODO list to take a look at how to do it as suggested
by Alexi on top of this set before posting a v2. Haven't had time
recently, though.

Cheers,

Tycho