From: Tycho Andersen <tycho@tycho.ws>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Kees Cook <keescook@chromium.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux Containers <containers@lists.linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
"Eric W . Biederman" <ebiederm@xmission.com>,
"Serge E . Hallyn" <serge@hallyn.com>,
Christian Brauner <christian.brauner@ubuntu.com>,
Tyler Hicks <tyhicks@canonical.com>,
Akihiro Suda <suda.akihiro@lab.ntt.co.jp>,
Tom Hromatka <tom.hromatka@oracle.com>,
Sargun Dhillon <sargun@sargun.me>, Paul Moore <pmoore@redhat.com>
Subject: Re: [RFC 1/3] seccomp: add a return code to trap to userspace
Date: Wed, 14 Feb 2018 10:23:00 -0700 [thread overview]
Message-ID: <20180214172300.7v2pre4rv4zzrj3s@cisco> (raw)
In-Reply-To: <CALCETrXeZZfVzXh7SwKhyB=+ySDk5fhrrdrXrcABsQ=JpQT7Tg@mail.gmail.com>
On Wed, Feb 14, 2018 at 05:19:52PM +0000, Andy Lutomirski wrote:
> On Wed, Feb 14, 2018 at 3:29 PM, Tycho Andersen <tycho@tycho.ws> wrote:
> > Hey Kees,
> >
> > Thanks for taking a look!
> >
> > On Tue, Feb 13, 2018 at 01:09:20PM -0800, Kees Cook wrote:
> >> On Sun, Feb 4, 2018 at 2:49 AM, Tycho Andersen <tycho@tycho.ws> wrote:
> >> > This patch introduces a means for syscalls matched in seccomp to notify
> >> > some other task that a particular filter has been triggered.
> >> >
> >> > The motivation for this is primarily for use with containers. For example,
> >> > if a container does an init_module(), we obviously don't want to load this
> >> > untrusted code, which may be compiled for the wrong version of the kernel
> >> > anyway. Instead, we could parse the module image, figure out which module
> >> > the container is trying to load and load it on the host.
> >> >
> >> > As another example, containers cannot mknod(), since this checks
> >> > capable(CAP_SYS_ADMIN). However, harmless devices like /dev/null or
> >> > /dev/zero should be ok for containers to mknod, but we'd like to avoid hard
> >> > coding some whitelist in the kernel. Another example is mount(), which has
> >> > many security restrictions for good reason, but configuration or runtime
> >> > knowledge could potentially be used to relax these restrictions.
> >>
> >> Related to the eBPF seccomp thread, can the logic for these things be
> >> handled entirely by eBPF? My assumption is that you still need to stop
> >> the process to do something (i.e. do a mknod, or a mount) before
> >> letting it continue. Is there some "wait for notification" system in
> >> eBPF?
> >
> > I replied in the other thread
> > (https://patchwork.ozlabs.org/cover/872938/#1856642 for those
> > following along at home), but no, at least not that I know of.
>
> eBPF can call functions. One of those functions could put the caller
> to sleep. In fact, I think I once proposed doing this for the seccomp
> logging action as well.
Yes, true. We could always add a bpf_func_map_lookup_wait or
something. I can look into that if it's preferable.
next prev parent reply other threads:[~2018-02-14 17:23 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-04 10:49 [RFC 0/3] seccomp trap to userspace Tycho Andersen
2018-02-04 10:49 ` [RFC 1/3] seccomp: add a return code to " Tycho Andersen
2018-02-04 17:36 ` Andy Lutomirski
2018-02-04 20:01 ` Tycho Andersen
2018-02-04 20:33 ` Andy Lutomirski
2018-02-05 8:47 ` Tycho Andersen
2018-02-13 21:09 ` Kees Cook
2018-02-14 15:29 ` Tycho Andersen
2018-02-14 17:19 ` Andy Lutomirski
2018-02-14 17:23 ` Tycho Andersen [this message]
2018-02-15 14:48 ` Christian Brauner
2018-02-27 0:49 ` Kees Cook
2018-02-27 3:27 ` Andy Lutomirski
2018-02-04 10:49 ` [RFC 2/3] seccomp: hoist out filter resolving logic Tycho Andersen
2018-02-13 21:29 ` Kees Cook
2018-02-14 15:33 ` Tycho Andersen
2018-02-04 10:49 ` [RFC 3/3] seccomp: add a way to get a listener fd from ptrace Tycho Andersen
2018-02-13 21:32 ` Kees Cook
2018-02-14 15:33 ` Tycho Andersen
2018-03-15 16:09 ` [RFC 0/3] seccomp trap to userspace Christian Brauner
2018-03-15 16:56 ` Andy Lutomirski
2018-03-15 17:05 ` Serge E. Hallyn
2018-03-15 17:11 ` Andy Lutomirski
2018-03-15 17:25 ` Christian Brauner
2018-03-15 17:30 ` Andy Lutomirski
2018-03-15 17:35 ` Tycho Andersen
2018-03-16 0:46 ` Andy Lutomirski
2018-03-16 14:47 ` Christian Brauner
2018-03-16 16:01 ` Andy Lutomirski
2018-03-16 16:40 ` Christian Brauner
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