From: Andy Lutomirski <luto@amacapital.net>
To: Colin Walters <walters@verbum.org>
Cc: Will Drewry <wad@chromium.org>,
linux-kernel@vger.kernel.org,
Casey Schaufler <casey@schaufler-ca.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Jamie Lokier <jamie@shareable.org>,
keescook@chromium.org, john.johansen@canonical.com,
serge.hallyn@canonical.com, coreyb@linux.vnet.ibm.com,
pmoore@redhat.com, eparis@redhat.com, djm@mindrot.org,
segoon@openwall.com, rostedt@goodmis.org, jmorris@namei.org,
scarybeasts@gmail.com, avi@redhat.com, penberg@cs.helsinki.fi,
viro@zeniv.linux.org.uk, mingo@elte.hu,
akpm@linux-foundation.org, khilman@ti.com,
borislav.petkov@amd.com, amwang@redhat.com, oleg@redhat.com,
ak@linux.intel.com, eric.dumazet@gmail.com, gregkh@suse.de,
dhowells@redhat.com, daniel.lezcano@free.fr,
linux-fsdevel@vger.kernel.org,
linux-security-module@vger.kernel.org, olofj@chromium.org,
mhalcrow@google.com, dlaor@redhat.com, corbet@lwn.net,
alan@lxorguk.ukuu.org.uk
Subject: Re: [PATCH v3 4/4] Allow unprivileged chroot when safe
Date: Mon, 30 Jan 2012 14:10:22 -0800 [thread overview]
Message-ID: <CALCETrWqOsWjnJOLD5TytOiSSiRE7wAwo6dRj5A7-jP-zEGa3A@mail.gmail.com> (raw)
In-Reply-To: <1327960736.5355.5.camel@lenny>
On Mon, Jan 30, 2012 at 1:58 PM, Colin Walters <walters@verbum.org> wrote:
> On Mon, 2012-01-30 at 08:17 -0800, Andy Lutomirski wrote:
>> Chroot can easily be used to subvert setuid programs. If no_new_privs,
>> then setuid programs don't gain any privilege, so allow chroot.
>
> Is this needed/desired by anyone now, or are you just using it to "demo"
> NO_NEW_PRIVS? I don't see it as very useful on its own, since in any
> "container"-type chroot you really want /proc and /dev, and your patch
> doesn't help with that.
It's a demo, but it could still be useful for container-ish things.
If something privileged sets up /proc, /sys, and /dev, then
unprivileged code can chroot into the container. This would allow
much simpler implementations of tools like schroot.
>
> System daemons that do chroot for a modicum of security already start
> privileged, so this doesn't help them either.
With this change, they wouldn't need to start privileged.
(Admittedly, this isn't a great argument for this patch.)
It would be really nice to have unprivileged filesystem namespace
features, but that would be more complicated to do safely.
--Andy
>
>
>
--
Andy Lutomirski
AMA Capital Management, LLC
Office: (310) 553-5322
Mobile: (650) 906-0647
next prev parent reply other threads:[~2012-01-30 22:10 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-30 16:17 [PATCH v3 0/4] PR_SET_NO_NEW_PRIVS, unshare, and chroot Andy Lutomirski
2012-01-30 16:17 ` [PATCH v3 1/4] Add PR_{GET,SET}_NO_NEW_PRIVS to prevent execve from granting privs Andy Lutomirski
2012-02-01 18:14 ` Kees Cook
2012-01-30 16:17 ` [PATCH v3 2/4] Fix apparmor for PR_{GET,SET}_NO_NEW_PRIVS Andy Lutomirski
2012-01-30 16:17 ` [PATCH v3 3/4] Allow unprivileged CLONE_NEWUTS and CLONE_NEWIPC with no_new_privs Andy Lutomirski
2012-02-01 19:02 ` Kees Cook
2012-02-01 20:35 ` Andy Lutomirski
2012-01-30 16:17 ` [PATCH v3 4/4] Allow unprivileged chroot when safe Andy Lutomirski
2012-01-30 21:58 ` Colin Walters
2012-01-30 22:10 ` Andy Lutomirski [this message]
2012-01-30 22:41 ` Colin Walters
2012-01-30 22:43 ` Andy Lutomirski
2012-01-30 23:10 ` Colin Walters
2012-01-30 23:15 ` Andy Lutomirski
2012-01-30 23:55 ` Colin Walters
2012-01-31 0:13 ` Andy Lutomirski
2012-01-30 22:18 ` Steven Rostedt
2012-01-30 22:28 ` Andy Lutomirski
2012-01-30 22:38 ` Will Drewry
2012-01-30 22:48 ` Colin Walters
2012-01-30 22:51 ` Andy Lutomirski
2012-02-09 9:35 ` Vasiliy Kulikov
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