Subject: Re: [PATCH net-next v2 2/2] bpf: Remove the capability check for cgroup skb eBPF program

From: Daniel Borkmann <[email-masked]>
Date: Tue, 06 Jun 2017 18:56:29 +0200

On 06/02/2017 01:42 AM, Alexei Starovoitov wrote:
> On Wed, May 31, 2017 at 06:16:00PM -0700, Chenbo Feng wrote:
>> From: Chenbo Feng <[email-masked]>
>>
>> Currently loading a cgroup skb eBPF program require a CAP_SYS_ADMIN
>> capability while attaching the program to a cgroup only requires the
>> user have CAP_NET_ADMIN privilege. We can escape the capability
>> check when load the program just like socket filter program to make
>> the capability requirement consistent.
>>
>> Change since v1:
>> Change the code style in order to be compliant with checkpatch.pl
>> preference
>>
>> Signed-off-by: Chenbo Feng <[email-masked]>
>
> as far as I can see they're indeed the same as socket filters, so
> Acked-by: Alexei Starovoitov <[email-masked]>
>
> but I don't quite understand how it helps, since as you said
> attaching such unpriv fd to cgroup still requires root.
> Do you have more patches to follow?

Hmm, when we relax this from capable(CAP_SYS_ADMIN) to unprivileged,
then we must at least also zero out the not-yet-initialized memory
for the mac header for egress case in __cgroup_bpf_run_filter_skb().