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

On Sep 4, 2019, at 6:32 PM, Alexei Starovoitov [off-list ref] wrote:

On Thu, Sep 05, 2019 at 12:34:36AM +0000, Song Liu wrote:

quoted

quoted

On Sep 4, 2019, at 11:43 AM, Alexei Starovoitov [off-list ref] wrote:

Implement permissions as stated in uapi/linux/capability.h

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

[...]

quoted

@@ -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