From: Kees Cook <keescook@chromium.org>
To: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: "kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"Andy Lutomirski" <luto@amacapital.net>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Richard Weinberger" <richard@nod.at>,
"Robert Święcki" <robert@swiecki.net>,
"Dmitry Vyukov" <dvyukov@google.com>,
"David Howells" <dhowells@redhat.com>,
"Kostya Serebryany" <kcc@google.com>,
"Alexander Potapenko" <glider@google.com>,
"Eric Dumazet" <edumazet@google.com>,
"Sasha Levin" <sasha.levin@oracle.com>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [kernel-hardening] Re: [PATCH 0/2] sysctl: allow CLONE_NEWUSER to be disabled
Date: Tue, 26 Jan 2016 15:13:29 -0800 [thread overview]
Message-ID: <CAGXu5j+kkzmnrvfOhcDfsK81bxwrgnywKQKCof+Pqjv-oVB+Kw@mail.gmail.com> (raw)
In-Reply-To: <20160126171523.GA13715@ubuntumail>
On Tue, Jan 26, 2016 at 9:15 AM, Serge Hallyn <serge.hallyn@ubuntu.com> wrote:
> Quoting Josh Boyer (jwboyer@fedoraproject.org):
>> What you're saying is true for the "oh crap" case of a new userns
>> related CVE being found. However, there is the case where sysadmins
>> know for a fact that a set of machines should not allow user
>> namespaces to be enabled. Currently they have 2 choices, 1) use their
>
> Hi - can you give a specific example of this? (Where users really should
> not be able to use them - not where they might not need them) I think
> it'll help the discussion tremendously. Because so far the only good
> arguments I've seen have been about actual bugs in the user namespaces,
> which would not warrant a designed-in permanent disable switch. If
> there are good use cases where such a disable switch will always be
> needed (and compiling out can't satisfy) that'd be helpful.
My example is a machine in a colo rack serving web pages. A site gets
attacked, and www-data uses user namespaces to continue their attack
to gain root privileges.
The admin of such a machine could have disabled userns months earlier
and limited the scope of the attack.
-Kees
--
Kees Cook
Chrome OS & Brillo Security
next prev parent reply other threads:[~2016-01-26 23:13 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-22 22:39 [PATCH 0/2] sysctl: allow CLONE_NEWUSER to be disabled Kees Cook
2016-01-22 22:39 ` [PATCH 1/2] sysctl: expand use of proc_dointvec_minmax_sysadmin Kees Cook
2016-01-23 3:10 ` Eric W. Biederman
2016-01-23 22:25 ` [kernel-hardening] " Jann Horn
2016-01-24 1:20 ` Eric W. Biederman
2016-01-24 1:43 ` Al Viro
2016-01-24 1:56 ` Jann Horn
2016-01-24 6:02 ` Eric W. Biederman
2016-01-24 6:32 ` Jann Horn
2016-01-24 6:44 ` Eric W. Biederman
2016-01-22 22:39 ` [PATCH 2/2] sysctl: allow CLONE_NEWUSER to be disabled Kees Cook
2016-01-22 22:47 ` Robert Święcki
2016-01-22 22:50 ` Kees Cook
2016-01-22 22:55 ` Robert Święcki
2016-01-22 23:00 ` Kees Cook
2016-01-23 0:44 ` Serge Hallyn
2016-01-23 0:44 ` Serge Hallyn
2016-01-23 0:59 ` [kernel-hardening] " Ben Hutchings
2016-01-24 20:59 ` Kees Cook
2016-01-24 22:20 ` Andy Lutomirski
2016-01-25 18:51 ` Kees Cook
2016-01-22 22:49 ` [PATCH 0/2] " Richard Weinberger
2016-01-23 3:02 ` Eric W. Biederman
2016-01-24 20:57 ` Kees Cook
2016-01-26 7:38 ` [kernel-hardening] " Serge Hallyn
2016-01-24 22:22 ` Andy Lutomirski
2016-01-25 18:51 ` Kees Cook
2016-01-25 18:53 ` Andy Lutomirski
2016-01-25 18:56 ` Kees Cook
2016-01-25 19:33 ` Eric W. Biederman
2016-01-25 22:34 ` Kees Cook
2016-01-25 23:33 ` Andy Lutomirski
2016-01-26 2:27 ` [kernel-hardening] " Daniel Micay
2016-01-26 4:57 ` Eric W. Biederman
2016-01-26 14:38 ` Josh Boyer
2016-01-26 14:46 ` Austin S. Hemmelgarn
2016-01-26 14:56 ` Josh Boyer
2016-01-26 17:20 ` [kernel-hardening] " Serge Hallyn
2016-01-26 19:56 ` Josh Boyer
2016-01-26 20:11 ` Austin S. Hemmelgarn
2016-01-26 17:15 ` Serge Hallyn
2016-01-26 18:09 ` Austin S. Hemmelgarn
2016-01-26 18:27 ` Andy Lutomirski
2016-01-26 18:45 ` Austin S. Hemmelgarn
2016-01-26 23:15 ` Kees Cook
2016-01-26 23:13 ` Kees Cook [this message]
2016-01-27 10:27 ` Eric W. Biederman
2016-01-27 12:32 ` Austin S. Hemmelgarn
2016-01-28 14:41 ` Robert Święcki
2016-01-26 16:37 ` Kees Cook
2016-01-28 8:56 ` [kernel-hardening] " Serge E. Hallyn
2016-01-28 12:53 ` Austin S. Hemmelgarn
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAGXu5j+kkzmnrvfOhcDfsK81bxwrgnywKQKCof+Pqjv-oVB+Kw@mail.gmail.com \
--to=keescook@chromium.org \
--cc=akpm@linux-foundation.org \
--cc=dhowells@redhat.com \
--cc=dvyukov@google.com \
--cc=ebiederm@xmission.com \
--cc=edumazet@google.com \
--cc=glider@google.com \
--cc=kcc@google.com \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=richard@nod.at \
--cc=robert@swiecki.net \
--cc=sasha.levin@oracle.com \
--cc=serge.hallyn@ubuntu.com \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).