linux-kernel - Re: [lxc-devel] [RFC PATCH 11/11] loop: Allow priveleged operations for root in the namespace which owns a device

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Message-ID: <1401118325.7572.82.camel@canyon.ip6.wittsend.com>
Date:	Mon, 26 May 2014 11:32:05 -0400
From:	"Michael H. Warfield" <mhw@...tsEnd.com>
To:	LXC development mailing-list <lxc-devel@...ts.linuxcontainers.org>
Cc:	"Michael H.Warfield" <mhw@...tsEnd.com>,
	Marian Marinov <mm@...com>, Jens Axboe <axboe@...nel.dk>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [lxc-devel] [RFC PATCH 11/11] loop: Allow priveleged operations
 for root in the namespace which owns a device

On Mon, 2014-05-26 at 11:16 +0200, Seth Forshee wrote:
> On Fri, May 23, 2014 at 08:48:25AM +0300, Marian Marinov wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> > 
> > One question about this patch.
> > 
> > Why don't you use the devices cgroup check if the root user in that namespace is allowed to use this device?
> > 
> > This way you can be sure that the root in that namespace can not access devices to which the host system did not gave
> > him access to.

> That might be possible, but I don't want to require something on the
> host to whitelist the device for the container. Then loop would need to
> automatically add the device to devices.allow, which doesn't seem
> desirable to me. But I'm not entirely opposed to the idea if others
> think this is a better way to go.

I don't see any safe way to avoid it.  The host has to be in control of
what devices can and can not be accessed by the container.

> Seth

Regards,
Mike
-- 
Michael H. Warfield (AI4NB) | (770) 978-7061 |  mhw@...tsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
   NIC whois: MHW9          | An optimist believes we live in the best of all
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