netdev - Re: [PATCH v2 bpf-next 1/3] capability: introduce CAP_BPF and CAP

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Date:   Thu, 29 Aug 2019 22:25:30 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Toke Høiland-Jørgensen <toke@...hat.com>
Cc:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Alexei Starovoitov <ast@...nel.org>, luto@...capital.net,
        davem@...emloft.net, peterz@...radead.org, rostedt@...dmis.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org, kernel-team@...com,
        linux-api@...r.kernel.org, brouer@...hat.com
Subject: Re: [PATCH v2 bpf-next 1/3] capability: introduce CAP_BPF and
 CAP_TRACING

On Thu, 29 Aug 2019 20:05:49 +0200
Toke Høiland-Jørgensen <toke@...hat.com> wrote:

> Alexei Starovoitov <alexei.starovoitov@...il.com> writes:
> 
> > On Thu, Aug 29, 2019 at 09:44:18AM +0200, Toke Høiland-Jørgensen wrote:  
> >> Alexei Starovoitov <ast@...nel.org> writes:
> >>   
> >> > CAP_BPF allows the following BPF operations:
> >> > - Loading all types of BPF programs
> >> > - Creating all types of BPF maps except:
> >> >    - stackmap that needs CAP_TRACING
> >> >    - devmap that needs CAP_NET_ADMIN
> >> >    - cpumap that needs CAP_SYS_ADMIN  
> >> 
> >> Why CAP_SYS_ADMIN instead of CAP_NET_ADMIN for cpumap?  
> >
> > Currently it's cap_sys_admin and I think it should stay this way
> > because it creates kthreads.  
> 
> Ah, right. I can sorta see that makes sense because of the kthreads, but
> it also means that you can use all of XDP *except* cpumap with
> CAP_NET_ADMIN+CAP_BPF. That is bound to create confusion, isn't it?
 
Hmm... I see 'cpumap' primarily as a network stack feature.  It is about
starting the network stack on a specific CPU, allocating and building
SKBs on that remote CPU.  It can only be used together with XDP_REDIRECT.
I would prefer CAP_NET_ADMIN like the devmap, to keep the XDP
capabilities consistent.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer