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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Andy Lutomirski <luto@amacapital.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>,
	"Mickaël Salaün" <mic@digikod.net>,
	"Daniel Mack" <daniel@zonque.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>
Subject: Re: [RFC v2 09/10] landlock: Handle cgroups
Date: Sat, 27 Aug 2016 11:11:55 -0700
Message-ID: <20160827181153.GB38754@ast-mbp.thefacebook.com> (raw)
In-Reply-To: <CALCETrVK1yQw=8ckLn3dcB4LuKft0NOrvQFoyFRs98ON00WgBw@mail.gmail.com>

On Sat, Aug 27, 2016 at 12:30:36AM -0700, Andy Lutomirski wrote:
> > cgroup is the common way to group multiple tasks.
> > Without cgroup only parent<->child relationship will be possible,
> > which will limit usability of such lsm to a master task that controls
> > its children. Such api restriction would have been ok, if we could
> > extend it in the future, but unfortunately task-centric won't allow it
> > without creating a parallel lsm that is cgroup based.
> > Therefore I think we have to go with cgroup-centric api and your
> > application has to use cgroups from the start though only parent-child
> > would have been enough.
> > Also I don't think the kernel can afford two bpf based lsm. One task
> > based and another cgroup based, so we have to find common ground
> > that suits both use cases.
> > Having unprivliged access is a subset. There is no strong reason why
> > cgroup+lsm+bpf should be limited to root only always.
> > When we can guarantee no pointer leaks, we can allow unpriv.
> 
> I don't really understand what you mean.  In the context of landlock,
> which is a *sandbox*, can one of you explain a use case that
> materially benefits from this type of cgroup usage?  I haven't thought
> of one.

In case of seccomp-like sandbox where parent controls child processes
cgroup is not needed. It's needed when container management software
needs to control a set of applications. If we can have one bpf-based lsm
that works via cgroup and without, I'd be fine with it. Right now
I haven't seen a plausible proposal to do that. Therefore cgroup based
api is a common api that works for sandbox as well, though requiring
parent to create a cgroup just to control a single child is cumbersome.

  reply index

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 [this message]
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
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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