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From: "Serge E. Hallyn" <serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>
To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: "Eric W. Biederman"
	<ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>,
	"Serge E. Hallyn" <serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>,
	Aditya Kali <adityakali-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 3/3] cgroupns: Only allow creation of hierarchies in the initial cgroup namespace
Date: Fri, 15 Jul 2016 11:39:26 -0500	[thread overview]
Message-ID: <20160715163926.GA18849@mail.hallyn.com> (raw)
In-Reply-To: <20160715120501.GF3078-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>

Quoting Tejun Heo (tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org):
> On Fri, Jul 15, 2016 at 06:36:44AM -0500, Eric W. Biederman wrote:
> > 
> > Unprivileged users can't use hierarchies if they create them as they do not
> > have privilieges to the root directory.
> > 
> > Which means the only thing a hiearchy created by an unprivileged user
> > is good for is expanding the number of cgroup links in every css_set,
> > which is a DOS attack.
> > 
> > We could allow hierarchies to be created in namespaces in the initial
> > user namespace.  Unfortunately there is only a single namespace for
> > the names of heirarchies, so that is likely to create more confusion
> > than not.
> > 
> > So do the simple thing and restrict hiearchy creation to the initial
> > cgroup namespace.
> > 
> > Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> > Fixes: a79a908fd2b0 ("cgroup: introduce cgroup namespaces")
> > Signed-off-by: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
> 
> Applied to cgroup/for-4.7-fixes.

Thanks, guys.

  parent reply	other threads:[~2016-07-15 16:39 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <87h9br4h80.fsf@x220.int.ebiederm.org>
     [not found] ` <87h9br4h80.fsf-JOvCrm2gF+uungPnsOpG7nhyD016LWXt@public.gmane.org>
2016-07-15  5:15   ` [PATCH 1/3] cgroupns: Fix the locking in copy_cgroup_ns Eric W. Biederman
2016-07-15  5:16   ` [PATCH 2/3] cgroupns: Close race between cgroup_post_fork and copy_cgroup_ns Eric W. Biederman
2016-07-15  5:17   ` [PATCH 3/3] cgroupns: Only allow creation of hierarchies in the initial cgroup namespace Eric W. Biederman
     [not found]     ` <87r3av32g1.fsf-JOvCrm2gF+uungPnsOpG7nhyD016LWXt@public.gmane.org>
2016-07-15 11:16       ` Tejun Heo
     [not found]         ` <20160715111659.GB3078-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2016-07-15 11:16           ` Eric W. Biederman
     [not found]             ` <8760s72lu5.fsf-JOvCrm2gF+uungPnsOpG7nhyD016LWXt@public.gmane.org>
2016-07-15 11:35               ` [PATCH 1/3] cgroupns: Fix the locking in copy_cgroup_ns Eric W. Biederman
2016-07-15 11:35               ` [PATCH 2/3] cgroupns: Close race between cgroup_post_fork and copy_cgroup_ns Eric W. Biederman
     [not found]                 ` <87mvlj16co.fsf_-_-JOvCrm2gF+uungPnsOpG7nhyD016LWXt@public.gmane.org>
2016-07-15 11:58                   ` Tejun Heo
2016-07-15 11:36               ` [PATCH 3/3] cgroupns: Only allow creation of hierarchies in the initial cgroup namespace Eric W. Biederman
     [not found]                 ` <87h9br16b7.fsf-JOvCrm2gF+uungPnsOpG7nhyD016LWXt@public.gmane.org>
2016-07-15 12:05                   ` Tejun Heo
     [not found]                     ` <20160715120501.GF3078-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2016-07-15 16:39                       ` Serge E. Hallyn [this message]
     [not found] ` <20160715111847.GC3078@mtj.duckdns.org>
     [not found]   ` <20160715111847.GC3078-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2016-07-15 11:34     ` [PATCH 0/3] cgroupns: Locking and semantic fixes Eric W. Biederman

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