linux-kernel - Re: [RFC] Unify KVM kernel-space and user-space code into a single project

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Message-ID: <20100324153746.GF14800@8bytes.org>
Date:	Wed, 24 Mar 2010 16:37:46 +0100
From:	Joerg Roedel <joro@...tes.org>
To:	"Daniel P. Berrange" <berrange@...hat.com>
Cc:	Avi Kivity <avi@...hat.com>,
	Anthony Liguori <anthony@...emonkey.ws>,
	Ingo Molnar <mingo@...e.hu>,
	Pekka Enberg <penberg@...helsinki.fi>,
	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Sheng Yang <sheng@...ux.intel.com>,
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Jes Sorensen <Jes.Sorensen@...hat.com>,
	Gleb Natapov <gleb@...hat.com>, ziteng.huang@...el.com,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Fr?d?ric Weisbecker <fweisbec@...il.com>,
	Gregory Haskins <ghaskins@...ell.com>
Subject: Re: [RFC] Unify KVM kernel-space and user-space code into a single
	project

On Wed, Mar 24, 2010 at 03:26:53PM +0000, Daniel P. Berrange wrote:
> On Wed, Mar 24, 2010 at 04:01:37PM +0100, Joerg Roedel wrote:
> > >> An approach like: "The files are owned and only readable by the same
> > >> user that started the vm." might be a good start. So a user can measure
> > >> its own guests and root can measure all of them.
> > >
> > > That's not how sVirt works.  sVirt isolates a user's VMs from each  
> > > other, so if a guest breaks into qemu it can't break into other guests  
> > > owned by the same user.
> > 
> > If a vm breaks into qemu it can access the host file system which is the
> > bigger problem. In this case there is no isolation anymore. From that
> > context it can even kill other VMs of the same user independent of a
> > hypothetical /sys/kvm/.
> 
> No it can't. With sVirt every single VM has a custom security label and
> the policy only allows it access to disks / files with a matching label,
> and prevents it attacking any other VMs or processes on the host. THis
> confines the scope of any exploit in QEMU to those resources the admin
> has explicitly assigned to the guest.

Even better. So a guest which breaks out can't even access its own
/sys/kvm/ directory. Perfect, it doesn't need that access anyway.

	Joerg

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