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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

  parent reply	other threads:[~2013-03-15 18:03 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-15  9:13 [PATCH 0/4] fix depvpts in user namespaces Glauber Costa
2013-03-15  9:13 ` 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
2013-03-15  9:13     ` 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 14:07       ` Serge Hallyn
2013-03-15 14:43         ` Glauber Costa
2013-03-15 14:43         ` Glauber Costa
2013-03-15 14:43           ` Glauber Costa
     [not found]           ` <514333A2.5060408-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2013-03-15 14:55             ` Serge Hallyn
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  9:13     ` Glauber Costa
     [not found]     ` <1363338823-25292-3-git-send-email-glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2013-03-15 14:20       ` Serge Hallyn
2013-03-15 14:20     ` Serge Hallyn
2013-03-19 15:32       ` Janne Karhunen
     [not found]         ` <CAE=Ncradvs_twWT8b6NQz85dm-Y8ayTH7NFv=i0vjYXpRBW9sg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-03-19 15:37           ` Serge Hallyn
2013-03-19 16:52             ` Janne Karhunen
     [not found]               ` <CAE=NcrYeKQYqkPsB9FG5PpYd2VTqmTszfpY39aRJqR=vsXfa7w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-03-19 17:27                 ` Serge Hallyn
2013-03-19 18:08                   ` Janne Karhunen
     [not found]                     ` <CAE=NcraBvk_hwCd9BgASpDBkmEB+fg-kKwAPbT7bQeFRbq5DSg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-03-19 19:15                       ` Serge Hallyn
2013-03-19 23:29                 ` Eric W. Biederman
2013-03-15  9:13   ` [PATCH 3/4] fs: allow mknod in user namespaces Glauber Costa
2013-03-15  9:13   ` Glauber Costa
2013-03-15  9:13     ` 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
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 15:14             ` Serge Hallyn
2013-03-15 14:49         ` Glauber Costa
2013-03-15 14:37       ` Serge Hallyn
2013-03-15 18:03       ` Vasily Kulikov
2013-03-15 20:43       ` Eric W. Biederman
2013-03-15 18:03     ` Vasily Kulikov [this message]
2013-03-15 20:43     ` Eric W. Biederman
2013-03-15 20:43       ` Eric W. Biederman
2013-03-16  0:23       ` Serge Hallyn
     [not found]       ` <87a9q4gzs1.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2013-03-16  0:23         ` Serge Hallyn
2013-03-15  9:13   ` [PATCH 4/4] devpts: fix usage " Glauber Costa
2013-03-15  9:13   ` Glauber Costa
2013-03-15  9:13     ` 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 14:45       ` Serge Hallyn
2013-03-15 10:26   ` [PATCH 0/4] fix depvpts " Eric W. Biederman
2013-03-15 14:00     ` Serge Hallyn
2013-03-15 14:42       ` Glauber Costa
2013-03-15 14:42       ` Glauber Costa
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
2013-03-15 15:26               ` Glauber Costa
2013-03-15 21:02               ` Eric W. Biederman
2013-03-15 21:02                 ` Eric W. Biederman
     [not found]                 ` <87txoce5qy.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2013-03-18  3:20                   ` Serge Hallyn
2013-03-18  3:20                 ` Serge Hallyn
2013-03-18 21:23                   ` Eric W. Biederman
     [not found]               ` <51433DBE.9020109-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2013-03-15 15:58                 ` Serge Hallyn
2013-03-15 15:58                 ` Serge Hallyn
2013-03-15 16:01                   ` Glauber Costa
2013-03-15 21:02                 ` Eric W. Biederman
2013-03-15 15:26             ` Glauber Costa
     [not found]     ` <87boalt0vi.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2013-03-15 12:01       ` Glauber Costa
2013-03-15 14:00       ` Serge Hallyn

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