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Message-ID: <CAEk6tEx0JRNX9q0k8JH2PNkGJO59WVVMhh4=3DkoQFMNkqY9LA@mail.gmail.com>
Date: Wed, 27 Jul 2016 13:49:14 -0700
From: Jessica Frazelle <me@...sfraz.com>
To: "oss-security@...ts.openwall.com" <oss-security@...ts.openwall.com>
Subject: Re: cve request: systemd-machined: information
exposure for docker containers
To be clear this is ONLY in Red Hat's fork of docker which is unsupported
by Docker. There is no oci-register-machine in docker itself.
On Wednesday, July 27, 2016, Jesse Hertz <jesse.hertz@...group.trust> wrote:
> Just to chime in here, since a docker container would be inside its own
> PID namespace, running ‘ps’ inside a container would not show you other
> processes/containers running on the same host.
> A similar “vulnerability" I “found” was patched in Docker earlier (tl;dr
> '/proc/sched_debug’ is not pid namespace aware).
>
> -jh
> > On Jul 27, 2016, at 4:00 PM, Christian Rebischke <
> Chris.Rebischke@...hlinux.org <javascript:;>> wrote:
> >
> > On Wed, Jul 27, 2016 at 01:27:08PM -0400, Daniel J Walsh wrote:
> >>
> >>
> >> On 07/27/2016 01:05 PM, Christian Rebischke wrote:
> >>> On Tue, Jul 26, 2016 at 03:24:13PM -0400, cve-assign@...re.org
> <javascript:;> wrote:
> >>>> -----BEGIN PGP SIGNED MESSAGE-----
> >>>> Hash: SHA256
> >>>>
> >>>>> Once docker containers register themselves to systemd-machined
> >>>>> by oci-register-machine. Any unprivileged user could run
> >>>>> machinectl to list every single containers running in the host
> >>>>> even if the containers do not belong to this user (including
> containers
> >>>>> belong to the root user), and access sensitive information associated
> >>>>> with any individual container including its internal IP address, OS
> >>>>> version, running processes, and file path for its rootfs.
> >>>>>
> >>>>> $ machinectl status cc8d10c7b9892b75843d200d54d34a3a
> >>>>> cc8d10c7b9892b75843d200d54d34a3a(63633864313063376239383932623735)
> >>>>> Since: Mon 2016-07-25 17:55:36 UTC; 34s ago
> >>>>> Leader: 43494 (sleep)
> >>>>> Service: docker; class container
> >>>>> Root:
> /var/mnt/overlay/overlay/0429684e3da515ae4f11b8514c7b20f759613
> >>>>> Address: 172.17.0.2
> >>>>> fe80::42:acff:fe11:2
> >>>>> OS: Red Hat Enterprise Linux Server 7.2 (Maipo)
> >>>>> Unit:
> docker-cc8d10c7b9892b75843d200d54d34a3a9435fe0f65527c254ebfd2d
> >>>>> 43494 sleep 3000
> >>>> Use CVE-2016-6349.
> >>> Hello,
> >>> I don't think that the bug for this problem lies in systemd.
> >>> It's more a design mistake in docker or oci-register-machine.
> >>> I have forwarded this issue to the systemd developer team and I don't
> >>> think they will fix this in the future. In their opinion it's a
> >>> bug in docker or oci-register-machine:
> >>>
> >>> https://github.com/systemd/systemd/issues/3815
> >>>
> >>> by the way.. I would feel glad if the security researchers would first
> >>> message the developers and then assign a CVE a bug. This is the normal
> >>> way for a full disclosure.
> >>>
> >>> best regards,
> >>>
> >>> Christian Rebischke
> >> Why is this a bug in oci-register-machine? All it is doing is calling
> >> the systemd-machine call to register with it using the three flags
> >> available.
> >> Is systemd saying we should not use that call?
> >
> > Let me quote Lennart Poettering:
> >
> > ---
> > machined is a system service and is for registering containers running
> > on the system. There's no concept of "user containers" with that, and
> > unprivileged users do not have the privileges to even register any
> > containers with machined.
> >
> > If you ask me the CVE is complete and utter rubbish. At least against
> > systemd. If Docker knows a concept of user containers, then good for
> > them, but in that case they shouldn't register them with machined
> > really, if they are not supposed to be visible on the host.
> >
> > Generally though I think the CVE is without merit entirely, after all
> > "ps" is generally unrestricted, and hence you can always see container
> > processes running on the host anyway.
> > ---
> >
> > In my opinion I would say you shouldn't use this call if you don't want
> > an information leak. Even if systemd would fix the output of
> > `machinectl status ..`. The information leak would still be there
> > because you could still see informations about the container with `ps`
> > or other tools. systemd is not designed for 'user containers'.
> >
> > If yo have further questions. I would say that you ask the
> > systemd-developers on their mailing list directly.
>
>
--
Jessie Frazelle
4096R / D4C4 DD60 0D66 F65A 8EFC 511E 18F3 685C 0022 BFF3
pgp.mit.edu <http://pgp.mit.edu/pks/lookup?op=get&search=0x18F3685C0022BFF3>
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