netdev - Re: [PATCH bpf-next 1/4] bpf: unprivileged BPF access via /dev/bpf

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Message-ID: <68BB91E5-B70C-4640-9550-8CAB62E5F6C6@fb.com>
Date:   Wed, 26 Jun 2019 16:10:25 +0000
From:   Song Liu <songliubraving@...com>
To:     Lorenz Bauer <lmb@...udflare.com>
CC:     Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        "Alexei Starovoitov" <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kernel Team <Kernel-team@...com>
Subject: Re: [PATCH bpf-next 1/4] bpf: unprivileged BPF access via /dev/bpf



> On Jun 26, 2019, at 8:26 AM, Lorenz Bauer <lmb@...udflare.com> wrote:
> 
> On Wed, 26 Jun 2019 at 16:19, Song Liu <songliubraving@...com> wrote:
>>> I know nothing about the scheduler, so pardon my ignorance. Does
>>> TASK_BPF_FLAG_PERMITTED apply per user-space process, or per thread?
>> 
>> It is per thread. clone() also clears the bit. I will make it more
>> clear int the commit log.
> 
> In that case this is going to be very hard if not impossible to use
> from languages that
> don't allow controlling threads, aka Go. I'm sure there are other
> examples as well.
> 
> Is it possible to make this per-process instead?

We can probably use CLONE_THREAD flag to differentiate clone() and 
fork(). I need to read it more carefully to determine whether this is 
accurate and safe. 

Thanks,
Song