From: Andy Lutomirski <luto@amacapital.net>
To: "Mickaël Salaün" <mic@digikod.net>
Cc: "kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Alexei Starovoitov <ast@kernel.org>, Tejun Heo <tj@kernel.org>,
Sargun Dhillon <sargun@sargun.me>,
Network Development <netdev@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Kees Cook <keescook@chromium.org>,
LSM List <linux-security-module@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"open list:CONTROL GROUP (CGROUP)" <cgroups@vger.kernel.org>,
"David S . Miller" <davem@davemloft.net>,
Daniel Mack <daniel@zonque.org>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Daniel Borkmann <daniel@iogearbox.net>
Subject: Re: [RFC v2 09/10] landlock: Handle cgroups (performance)
Date: Sun, 28 Aug 2016 01:13:13 -0700 [thread overview]
Message-ID: <CALCETrXgQ+njtupXiKcOXG8ZRzD=n2LhT45NiJr1Ehob7bHskQ@mail.gmail.com> (raw)
In-Reply-To: <57C202BF.7000207@digikod.net>
On Aug 27, 2016 11:14 PM, "Mickaël Salaün" <mic@digikod.net> wrote:
>
>
> On 27/08/2016 22:43, Alexei Starovoitov wrote:
> > On Sat, Aug 27, 2016 at 09:35:14PM +0200, Mickaël Salaün wrote:
> >> On 27/08/2016 20:06, Alexei Starovoitov wrote:
> >>> On Sat, Aug 27, 2016 at 04:06:38PM +0200, Mickaël Salaün wrote:
> >>>> As said above, Landlock will not run an eBPF programs when not strictly
> >>>> needed. Attaching to a cgroup will have the same performance impact as
> >>>> attaching to a process hierarchy.
> >>>
> >>> Having a prog per cgroup per lsm_hook is the only scalable way I
> >>> could come up with. If you see another way, please propose.
> >>> current->seccomp.landlock_prog is not the answer.
> >>
> >> Hum, I don't see the difference from a performance point of view between
> >> a cgroup-based or a process hierarchy-based system.
> >>
> >> Maybe a better option should be to use an array of pointers with N
> >> entries, one for each supported hook, instead of a unique pointer list?
> >
> > yes, clearly array dereference is faster than link list walk.
> > Now the question is where to keep this prog_array[num_lsm_hooks] ?
> > Since we cannot keep it inside task_struct, we have to allocate it.
> > Every time the task is creted then. What to do on the fork? That
> > will require changes all over. Then the obvious optimization would be
> > to share this allocated array of prog pointers across multiple tasks...
> > and little by little this new facility will look like cgroup.
> > Hence the suggestion to put this array into cgroup from the start.
>
> I see your point :)
>
> >
> >> Anyway, being able to attach an LSM hook program to a cgroup thanks to
> >> the new BPF_PROG_ATTACH seems a good idea (while keeping the possibility
> >> to use a process hierarchy). The downside will be to handle an LSM hook
> >> program which is not triggered by a seccomp-filter, but this should be
> >> needed anyway to handle interruptions.
> >
> > what do you mean 'not triggered by seccomp' ?
> > You're not suggesting that this lsm has to enable seccomp to be functional?
> > imo that's non starter due to overhead.
>
> Yes, for now, it is triggered by a new seccomp filter return value
> RET_LANDLOCK, which can take a 16-bit value called cookie. This must not
> be needed but could be useful to bind a seccomp filter security policy
> with a Landlock one. Waiting for Kees's point of view…
>
I'm not Kees, but I'd be okay with that. I still think that doing
this by process hierarchy a la seccomp will be easier to use and to
understand (which is quite important for this kind of work) than doing
it by cgroup.
A feature I've wanted to add for a while is to have an fd that
represents a seccomp layer, the idea being that you would set up your
seccomp layer (with syscall filter, landlock hooks, etc) and then you
would have a syscall to install that layer. Then an unprivileged
sandbox manager could set up its layer and still be able to inject new
processes into it later on, no cgroups needed.
--Andy
next prev parent reply other threads:[~2016-08-28 8:13 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-25 10:32 [RFC v2 00/10] Landlock LSM: Unprivileged sandboxing Mickaël Salaün
2016-08-25 10:32 ` [RFC v2 01/10] landlock: Add Kconfig Mickaël Salaün
2016-08-25 10:32 ` [RFC v2 02/10] bpf: Move u64_to_ptr() to BPF headers and inline it Mickaël Salaün
2016-08-25 10:32 ` [RFC v2 03/10] bpf,landlock: Add a new arraymap type to deal with (Landlock) handles Mickaël Salaün
2016-08-25 10:32 ` [RFC v2 04/10] seccomp: Split put_seccomp_filter() with put_seccomp() Mickaël Salaün
2016-08-25 10:32 ` [RFC v2 05/10] seccomp: Handle Landlock Mickaël Salaün
2016-08-25 10:32 ` [RFC v2 06/10] landlock: Add LSM hooks Mickaël Salaün
2016-08-30 18:56 ` Andy Lutomirski
2016-08-30 20:10 ` Mickaël Salaün
2016-08-30 20:18 ` Andy Lutomirski
2016-08-30 20:27 ` Mickaël Salaün
2016-08-25 10:32 ` [RFC v2 07/10] landlock: Add errno check Mickaël Salaün
2016-08-25 11:13 ` Andy Lutomirski
2016-08-25 10:32 ` [RFC v2 08/10] landlock: Handle file system comparisons Mickaël Salaün
2016-08-25 11:12 ` Andy Lutomirski
2016-08-25 14:10 ` Mickaël Salaün
2016-08-26 14:57 ` Andy Lutomirski
2016-08-27 13:45 ` Mickaël Salaün
2016-08-25 10:32 ` [RFC v2 09/10] landlock: Handle cgroups Mickaël Salaün
2016-08-25 11:09 ` Andy Lutomirski
2016-08-25 14:44 ` Mickaël Salaün
2016-08-26 12:55 ` Tejun Heo
2016-08-26 14:20 ` Andy Lutomirski
2016-08-26 15:50 ` Tejun Heo
2016-08-26 2:14 ` Alexei Starovoitov
2016-08-26 15:10 ` Mickaël Salaün
2016-08-26 23:05 ` Alexei Starovoitov
2016-08-27 7:30 ` Andy Lutomirski
2016-08-27 18:11 ` Alexei Starovoitov
2016-08-28 8:14 ` Andy Lutomirski
2016-08-27 14:06 ` [RFC v2 09/10] landlock: Handle cgroups (performance) Mickaël Salaün
2016-08-27 18:06 ` Alexei Starovoitov
2016-08-27 19:35 ` Mickaël Salaün
2016-08-27 20:43 ` Alexei Starovoitov
2016-08-27 21:14 ` Mickaël Salaün
2016-08-28 8:13 ` Andy Lutomirski [this message]
2016-08-28 9:42 ` Mickaël Salaün
2016-08-30 18:55 ` Andy Lutomirski
2016-08-30 20:20 ` Mickaël Salaün
2016-08-30 20:23 ` Andy Lutomirski
2016-08-30 20:33 ` Mickaël Salaün
2016-08-30 20:55 ` Alexei Starovoitov
2016-08-30 21:45 ` Andy Lutomirski
2016-08-31 1:36 ` Alexei Starovoitov
2016-08-31 3:29 ` Andy Lutomirski
2016-08-27 14:19 ` [RFC v2 09/10] landlock: Handle cgroups (netfilter match) Mickaël Salaün
2016-08-27 18:32 ` Alexei Starovoitov
2016-08-27 14:34 ` [RFC v2 09/10] landlock: Handle cgroups (program types) Mickaël Salaün
2016-08-27 18:19 ` Alexei Starovoitov
2016-08-27 19:55 ` Mickaël Salaün
2016-08-27 20:56 ` Alexei Starovoitov
2016-08-27 21:18 ` Mickaël Salaün
2016-08-25 10:32 ` [RFC v2 10/10] samples/landlock: Add sandbox example Mickaël Salaün
2016-08-25 11:05 ` [RFC v2 00/10] Landlock LSM: Unprivileged sandboxing Andy Lutomirski
2016-08-25 13:57 ` Mickaël Salaün
2016-08-27 7:40 ` Andy Lutomirski
2016-08-27 15:10 ` Mickaël Salaün
2016-08-27 15:21 ` [RFC v2 00/10] Landlock LSM: Unprivileged sandboxing (cgroup delegation) Mickaël Salaün
2016-08-30 16:06 ` [RFC v2 00/10] Landlock LSM: Unprivileged sandboxing Andy Lutomirski
2016-08-30 19:51 ` Mickaël Salaün
2016-08-30 19:55 ` Andy Lutomirski
2016-09-15 9:19 ` Pavel Machek
2016-09-20 17:08 ` Mickaël Salaün
2016-09-24 7:45 ` Pavel Machek
2016-10-03 22:56 ` Kees Cook
2016-10-05 20:30 ` Mickaël Salaün
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