netdev - Re: Permissions for eBPF objects

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Date:   Mon, 28 Aug 2017 18:44:25 -0700
From:   Chenbo Feng <fengc@...gle.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Jeffrey Vander Stoep <jeffv@...gle.com>,
        Stephen Smalley <sds@...ho.nsa.gov>, netdev@...r.kernel.org,
        SELinux <Selinux@...ho.nsa.gov>,
        Mickaël Salaün <mic@...ikod.net>
Subject: Re: Permissions for eBPF objects

On Mon, Aug 28, 2017 at 6:15 PM, Alexei Starovoitov
<alexei.starovoitov@...il.com> wrote:
> On Mon, Aug 28, 2017 at 05:47:19PM -0700, Chenbo Feng wrote:
>> On Fri, Aug 25, 2017 at 6:03 PM, Alexei Starovoitov
>> <alexei.starovoitov@...il.com> wrote:
>> > On Fri, Aug 25, 2017 at 10:07:27PM +0200, Daniel Borkmann wrote:
>> >> On 08/25/2017 09:52 PM, Chenbo Feng wrote:
>> >> > On Fri, Aug 25, 2017 at 12:45 PM, Jeffrey Vander Stoep <jeffv@...gle.com> wrote:
>> >> > > On Fri, Aug 25, 2017 at 12:26 PM, Stephen Smalley <sds@...ho.nsa.gov> wrote:
>> >> > > > On Fri, 2017-08-25 at 11:01 -0700, Jeffrey Vander Stoep via Selinux
>> >> > > > wrote:
>> >> > > > > I’d like to get your thoughts on adding LSM permission checks on BPF
>> >> > > > > objects.
>> >
>> > before reinventing the wheel please take a look at landlock work.
>> > Everything that was discussed in this thread is covered by it.
>> > The patches have been in development for more than a year and most of the early
>> > issues have been resolved.
>> > It will be presented again during security summit in LA in September.
>> >
>> I am not very familiar with landlock lsm, isn't this module also
>> depend on the lsm hooks to do
>> the landlock check? If so then adding lsm hooks for eBPF object seems
>> not conflict with the
>> work on progress.
>
> I see. I got it the other way around. What lsm checks are you proposing?
> and why unprivileged_bpf_disabled is not enough?
> you want to allow unpriv only for specific user(s) ?
>
Exactly, the proposal patch I am currently working on will add checks
before map creation,
map read,  and map modify, since all these functionalities will be
available to all users when
unprivileged_bpf_disabled is turned off. And eBPF prog_load may also
need a check as well
since loading some types of program is not restricted either.