From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758272AbYDAWHe (ORCPT ); Tue, 1 Apr 2008 18:07:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752790AbYDAWHZ (ORCPT ); Tue, 1 Apr 2008 18:07:25 -0400 Received: from e3.ny.us.ibm.com ([32.97.182.143]:36420 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751955AbYDAWHY (ORCPT ); Tue, 1 Apr 2008 18:07:24 -0400 Date: Tue, 1 Apr 2008 17:07:22 -0500 From: "Serge E. Hallyn" To: Pavel Machek Cc: "Serge E. Hallyn" , lkml , daniel@hozac.com, lizf@cn.fujitsu.com, Pavel Emelyanov , Greg KH , Andrew Morton Subject: Re: [PATCH 1/1] cgroups: implement device whitelist (v6) Message-ID: <20080401220722.GA6317@sergelap.austin.ibm.com> References: <20080326180543.GA27709@sergelap.austin.ibm.com> <20080329081839.GA4423@ucw.cz> <20080331140053.GA9909@sergelap.austin.ibm.com> <20080401123218.GE12129@elf.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080401123218.GE12129@elf.ucw.cz> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Quoting Pavel Machek (pavel@ucw.cz): > On Mon 2008-03-31 09:00:53, Serge E. Hallyn wrote: > > Quoting Pavel Machek (pavel@ucw.cz): > > > On Wed 2008-03-26 13:05:43, Serge E. Hallyn wrote: > > > > (This is identical to the version I sent on Mar 19 in response to > > > > the comments by Daniel Hokka Zakrisson, which are the last > > > > comments I've gotten.) > > > > > > > > Implement a cgroup to track and enforce open and mknod restrictions on device > > > > files. A device cgroup associates a device access whitelist with each > > > > cgroup. A whitelist entry has 4 fields. 'type' is a (all), c (char), or > > > > b (block). 'all' means it applies to all types and all major and minor > > > > numbers. Major and minor are either an integer or * for all. > > > > Access is a composition of r (read), w (write), and m (mknod). > > > > > > > > The root device cgroup starts with rwm to 'all'. A child devcg gets > > > > a copy of the parent. Admins can then remove devices from the > > > > whitelist or add new entries. A child cgroup can never receive a > > > > device access which is denied its parent. However when a device > > > > access is removed from a parent it will not also be removed from the > > > > child(ren). > > > > > > > > An entry is added using devices.allow, and removed using > > > > devices.deny. For instance > > > > > > > > echo 'c 1:3 mr' > /cgroups/1/devices.allow > > > > > > > > allows cgroup 1 to read and mknod the device usually known as > > > > /dev/null. Doing > > > > > > > > echo a > /cgroups/1/devices.deny > > > > > > Can't you use selinux or something? > > > > No. At the moment SELinux can't authorize based on type/major:minor. I > > would like to add that support later on, but even when I do, folks such > > as the openvz folks do not want to rely on any security modules. > > Yep, it looks like openvz folks do not want to rely on any security > modules, do not want to fix their userland, and do not have a taste > when implementing new features. > > IMO that means openvz folks should be kept off mainline. > > Implementing SELinux extension that can authorize based on > type/major:minor seems like a way to go to me.... If we go with the decision that properly isolated containers will always require an LSM then I can go with that. But IMO such a decision needs agreement by all the players. So far it seems there is only calls from one objector. Eric, I don't recall - was it your opinion that an LSM was an ok short-term solution, or that it was in fact an ok long-term solution? > > > > --- a/include/linux/cgroup_subsys.h > > > > +++ b/include/linux/cgroup_subsys.h > > > > @@ -42,3 +42,9 @@ SUBSYS(mem_cgroup) > > > > #endif > > > > > > > > /* */ > > > > + > > > > +#ifdef CONFIG_CGROUP_DEVICE > > > > +SUBSYS(devices) > > > > +#endif > > > > + > > > > +/* */ > > > > > > I don't know what this is, but it does not look like C... > > > > Huh? > > Empty comments as separators? What does magical SUBSYS macro do? > Pavel > -- > (english) http://www.livejournal.com/~pavelmachek > (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html