netdev - Re: [RFC PATCH bpf-next 0/2] unprivileged BPF_PROG_TEST

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Message-ID: <20191219154704.GC4198@linux-9.fritz.box>
Date:   Thu, 19 Dec 2019 16:47:04 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Edwin Peer <epeer@...iper.net>
Cc:     Y Song <ys114321@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "ast@...nel.org" <ast@...nel.org>, bpf <bpf@...r.kernel.org>
Subject: Re: [RFC PATCH bpf-next 0/2] unprivileged BPF_PROG_TEST_RUN

On Thu, Dec 19, 2019 at 02:50:42PM +0000, Edwin Peer wrote:
> On 12/18/19, 23:19, "Y Song" <ys114321@...il.com> wrote:
> 
> >  Added cc to bpf@...r.kernel.org.
>
> Thank you, I will remember to do this next time.
>
> > Have you tried your patch with some bpf programs? verifier and jit  put some
> > restrictions on unpriv programs. To truely test the program, most if not all these
> > restrictions should be lifted, so the same tested program should be able to
> > run on production server and vice verse.
> 
> Agreed, I am aware of some of these differences in the load/verifier behavior with and without
> CAP_SYS_ADMIN. In particular, without CAP_SYS_ADMIN programs are still restricted to 4k, some helpers are not available (spin locks, trace printk) and there are some differences in context access checks.
> 
> I think these can be addressed incrementally, assuming folk are on board with this approach in general?

What about CAP_BPF? IIRC, there are also other issues e.g. you could abuse
the test interface as a packet generator (bpf_clone_redirect) which is not
something fully unpriv should be doing.

Thanks,
Daniel