From: Vasily Kulikov <segoon@openwall.com>
To: Glauber Costa <glommer@parallels.com>
Cc: cgroups@vger.kernel.org, containers@lists.linux-foundation.org,
Aristeu Rozanski <aris@redhat.com>,
mtk.manpages@gmail.com, linux-fsdevel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH 3/4] fs: allow mknod in user namespaces
Date: Fri, 15 Mar 2013 22:03:08 +0400 [thread overview]
Message-ID: <20130315180308.GA5526@cachalot> (raw)
In-Reply-To: <1363338823-25292-4-git-send-email-glommer@parallels.com>
On Fri, Mar 15, 2013 at 13:13 +0400, Glauber Costa wrote:
> Since we have strict control on who access the devices, it should be
> no problem to allow the device to appear.
...
> - if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
> + if ((S_ISCHR(mode) || S_ISBLK(mode)) && !nsown_capable(CAP_MKNOD))
As now we have several mechanisms for dev nodes usage in containers
(cgroup, per-fs flags, CAP_MKNOD), probably it's better to document
all this stuff in a single document? Enumerate all possible limits
of device files creation and usage, and describe unobvious ways to
abuse the API to escape from a container (allow loopback device?
allow ext4? just guessing, didn't investigate myself). It should
document several safe patterns for common cases and beware of
known-to-be-vulnerable ones.
Thanks,
--
Vasily Kulikov
http://www.openwall.com - bringing security into open computing environments
next prev parent reply other threads:[~2013-03-15 18:03 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-15 9:13 [PATCH 0/4] fix depvpts in user namespaces Glauber Costa
[not found] ` <1363338823-25292-1-git-send-email-glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2013-03-15 9:13 ` [PATCH 1/4] dev_cgroup: keep track of which cgroup is the root cgroup Glauber Costa
[not found] ` <1363338823-25292-2-git-send-email-glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2013-03-15 14:07 ` Serge Hallyn
2013-03-15 14:43 ` Glauber Costa
2013-03-15 14:55 ` Serge Hallyn
2013-03-15 19:27 ` Aristeu Rozanski
2013-03-15 9:13 ` [PATCH 2/4] fs: allow dev accesses in userns in controlled situations Glauber Costa
2013-03-15 14:20 ` Serge Hallyn
2013-03-15 9:13 ` [PATCH 3/4] fs: allow mknod in user namespaces Glauber Costa
[not found] ` <1363338823-25292-4-git-send-email-glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2013-03-15 14:37 ` Serge Hallyn
2013-03-15 14:49 ` Glauber Costa
[not found] ` <51433511.1020808-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2013-03-15 15:14 ` Serge Hallyn
2013-03-15 18:03 ` Vasily Kulikov [this message]
2013-03-15 20:43 ` Eric W. Biederman
2013-03-16 0:23 ` Serge Hallyn
2013-03-15 9:13 ` [PATCH 4/4] devpts: fix usage " Glauber Costa
[not found] ` <1363338823-25292-5-git-send-email-glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2013-03-15 14:45 ` Serge Hallyn
2013-03-15 10:26 ` [PATCH 0/4] fix depvpts " Eric W. Biederman
[not found] ` <87boalt0vi.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2013-03-15 12:01 ` Glauber Costa
2013-03-15 14:00 ` Serge Hallyn
2013-03-15 14:42 ` Glauber Costa
[not found] ` <5143333E.1040100-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2013-03-15 15:21 ` Serge Hallyn
2013-03-15 15:26 ` Glauber Costa
[not found] ` <51433DBE.9020109-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2013-03-15 15:58 ` Serge Hallyn
2013-03-15 16:01 ` Glauber Costa
2013-03-15 21:02 ` Eric W. Biederman
2013-03-18 3:20 ` Serge Hallyn
2013-03-18 21:23 ` Eric W. Biederman
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=20130315180308.GA5526@cachalot \
--to=segoon@openwall.com \
--cc=akpm@linux-foundation.org \
--cc=aris@redhat.com \
--cc=cgroups@vger.kernel.org \
--cc=containers@lists.linux-foundation.org \
--cc=ebiederm@xmission.com \
--cc=glommer@parallels.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=mtk.manpages@gmail.com \
/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).