linux-kernel - Re: [PATCH v2 net-next 1/3] bpf: enable non-root eBPF programs

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Date:	Fri, 9 Oct 2015 10:59:23 -0700
From:	Alexei Starovoitov <ast@...mgrid.com>
To:	Daniel Borkmann <daniel@...earbox.net>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	"David S. Miller" <davem@...emloft.net>
Cc:	Andy Lutomirski <luto@...capital.net>,
	Ingo Molnar <mingo@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Kees Cook <keescook@...omium.org>, linux-api@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 net-next 1/3] bpf: enable non-root eBPF programs

On 10/9/15 10:45 AM, Daniel Borkmann wrote:
> On 10/09/2015 07:30 PM, Alexei Starovoitov wrote:
> ...
>> Openstack use case is different. There it will be prog_type_sched_cls
>> that can mangle packets, change skb metadata, etc under TC framework.
>> These are not suitable for all users and this patch leaves
>> them root-only. If you're proposing to add CAP_BPF_TC to let containers
>> use them without being CAP_SYS_ADMIN, then I agree, it is useful, but
>> needs a lot more safety analysis on tc side.
>
> Well, I think if so, then this would need to be something generic for
> tc instead of being specific to a single (out of various) entities
> inside the tc framework, but I currently doubt that this makes much
> sense. If we allow to operate already at that level, then restricting
> to CAP_SYS_ADMIN makes more sense in that specific context/subsys to me.

Let me rephrase. I think it would be useful, but I have my doubts that
it's manageable, since analyzing dark corners of TC is not trivial.
Probably easier to allow prog_type_sched_cls/act under CAP_NET_ADMIN
and grant that to trusted apps. Though only tiny bit better than
requiring CAP_SYS_ADMIN.

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