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

On Thu, Aug 29, 2019 at 10:25:30PM +0200, Jesper Dangaard Brouer wrote:

On Thu, 29 Aug 2019 20:05:49 +0200
Toke Høiland-Jørgensen [off-list ref] wrote:

quoted

Alexei Starovoitov [off-list ref] writes:

quoted

On Thu, Aug 29, 2019 at 09:44:18AM +0200, Toke Høiland-Jørgensen wrote:  

quoted

Alexei Starovoitov [off-list ref] writes:
  

quoted

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.

I don't mind relaxing cpumap to cap_net_admin.
Looking at the reaction to the rest of the set. I'd rather discuss it
and do it later after basic cap_bpf is in.