Re: [PATCH v3 bpf-next 2/3] bpf: implement CAP_BPF

[Song Liu <songliubraving@fb.com>]

> On Sep 4, 2019, at 6:32 PM, Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:
> 
> On Thu, Sep 05, 2019 at 12:34:36AM +0000, Song Liu wrote:
>> 
>> 
>>> On Sep 4, 2019, at 11:43 AM, Alexei Starovoitov <ast@kernel.org> wrote:
>>> 
>>> Implement permissions as stated in uapi/linux/capability.h
>>> 
>>> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
>>> 
>> 
>> [...]
>> 
>>> @@ -1648,11 +1648,11 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
>>> 	is_gpl = license_is_gpl_compatible(license);
>>> 
>>> 	if (attr->insn_cnt == 0 ||
>>> -	    attr->insn_cnt > (capable(CAP_SYS_ADMIN) ? BPF_COMPLEXITY_LIMIT_INSNS : BPF_MAXINSNS))
>>> +	    attr->insn_cnt > (capable_bpf() ? BPF_COMPLEXITY_LIMIT_INSNS : BPF_MAXINSNS))
>>> 		return -E2BIG;
>>> 	if (type != BPF_PROG_TYPE_SOCKET_FILTER &&
>>> 	    type != BPF_PROG_TYPE_CGROUP_SKB &&
>>> -	    !capable(CAP_SYS_ADMIN))
>>> +	    !capable_bpf())
>>> 		return -EPERM;
>> 
>> Do we allow load BPF_PROG_TYPE_SOCKET_FILTER and BPF_PROG_TYPE_CGROUP_SKB
>> without CAP_BPF? If so, maybe highlight in the header?
> 
> of course. there is no change in behavior.
> 'highlight in the header'?
> you mean in commit log?
> I think it's a bit weird to describe things in commit that patch
> is _not_ changing vs things that patch does actually change.
> This type of comment would be great in a doc though.
> The doc will be coming separately in the follow up assuming
> the whole thing lands. I'll remember to note that bit.

I meant capability.h:

+ * CAP_BPF allows the following BPF operations:
+ * - Loading all types of BPF programs

But CAP_BPF is not required to load all types of programs. 

On a second thought, I am not sure whether we will keep capability.h
up to date with all features. So this is probably OK. 

Thanks,
Song