From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:46802) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QvYWF-0004c7-53 for qemu-devel@nongnu.org; Mon, 22 Aug 2011 13:42:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QvYWD-0001t9-VB for qemu-devel@nongnu.org; Mon, 22 Aug 2011 13:42:39 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:47024) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QvYWD-0001t5-Nm for qemu-devel@nongnu.org; Mon, 22 Aug 2011 13:42:37 -0400 Received: from d03relay05.boulder.ibm.com (d03relay05.boulder.ibm.com [9.17.195.107]) by e33.co.us.ibm.com (8.14.4/8.13.1) with ESMTP id p7MHYWhE009133 for ; Mon, 22 Aug 2011 11:34:32 -0600 Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d03relay05.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p7MHg4P5021248 for ; Mon, 22 Aug 2011 11:42:08 -0600 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p7MBg37l006032 for ; Mon, 22 Aug 2011 05:42:03 -0600 Message-ID: <4E5294EA.1050007@linux.vnet.ibm.com> Date: Mon, 22 Aug 2011 13:42:02 -0400 From: Corey Bryant MIME-Version: 1.0 References: <1314024650-28510-1-git-send-email-coreyb@linux.vnet.ibm.com> <20110822153820.GA4774@lst.de> <20110822162444.GI9456@redhat.com> <4E5283D8.9000309@codemonkey.ws> <20110822165014.GM9456@redhat.com> <4E529105.2010907@us.ibm.com> In-Reply-To: <4E529105.2010907@us.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [libvirt] [PATCH v4] Add support for fd: protocol List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: kwolf@redhat.com, libvir-list@redhat.com, Christoph Hellwig , qemu-devel@nongnu.org On 08/22/2011 01:25 PM, Anthony Liguori wrote: > On 08/22/2011 11:50 AM, Daniel P. Berrange wrote: >> On Mon, Aug 22, 2011 at 11:29:12AM -0500, Anthony Liguori wrote: >>> I don't think it makes sense to have qemu-fe do dynamic labelling. >>> You certainly could avoid the fd passing by having qemu-fe do the >>> open though and just let qemu-fe run without the restricted security >>> context. >> >> qemu-fe would also not be entirely simple, > > Indeed. > I do like the idea of a privileged qemu-fe performing the open and passing the fd to a restricted qemu. However, I get the impression that this won't get delivered nearly as quickly as fd: passing could be. How soon do we need image isolation for NFS? Btw, this sounds similar to what Blue Swirl recommended here on v1 of this patch: http://lists.gnu.org/archive/html/qemu-devel/2011-05/msg02187.html Regards, Corey >> because it will need to act >> as a proxy for the monitor, in order to make hotplug work. ie the mgmt >> app would be sending 'drive_add file:/foo/bar' to qemu-fe, which would >> then have to open the file and send 'drive_add fd:NN' onto the real QEMU, >> and then pass the results on back. >> >> In addition qemu-fe would still have to be under some kind of restricted >> security context for it to be acceptable. This is going to want to be as >> locked down as possible. > > I think there's got to be some give and take here. > > It should at least be as locked down as libvirtd. From a security point > of view, we should be able to agree that we want libvirtd to be as > locked down as possible. > > But there shouldn't be a hard requirement to lock down qemu-fe more than > libvirtd. Instead, the requirement should be for qemu-fe to be as/more > vigilant in not trusting qemu-system-x86_64 as libvirtd is. > > The fundamental problem here, is that there is some logic in libvirtd > that rightly belongs in QEMU. In order to preserve the security model, > that means that we're going to have to take a subsection of QEMU and > trust it more. > >> So I'd see that you'd likely end up with the >> qemu-fe security policy being identical to the qemu security policy, > > Then there's no point in doing qemu-fe. qemu-fe should be thought of as > QEMU supplied libvirtd plugin. > >> with the exception that it would be allowed to open files on NFS without >> needing them to be labelled. So I don't really see that all this gives us >> any tangible benefits over just allowing the mgmt app to pass in the FDs >> directly. >> >>> But libvirt would still need to parse image files. >> >> Not neccessarily. As mentioned below, it is entirely possible to >> enable the mgmt app to pass in details of the backing files, at >> which point no image parsing is required by libvirt. Hence my >> assertion that the question of who does image parsing is irrelevant >> to this discussion. > > That's certainly true. > > Regards, > > Anthony Liguori