Re: [Qemu-devel] [multiprocess RFC PATCH 36/37] multi-process: add the concept description to docs/devel/qemu-multiprocess

[Jag Raman]

On 3/26/2019 4:08 AM, Stefan Hajnoczi wrote:
> On Fri, Mar 08, 2019 at 09:50:36AM +0000, Stefan Hajnoczi wrote:
> > On Thu, Mar 07, 2019 at 03:29:41PM -0800, John G Johnson wrote:
> > > > On Mar 7, 2019, at 11:27 AM, Stefan Hajnoczi <address@hidden> wrote:
> > > > On Thu, Mar 07, 2019 at 02:51:20PM +0000, Daniel P. Berrangé wrote:
> > > > > On Thu, Mar 07, 2019 at 02:26:09PM +0000, Stefan Hajnoczi wrote:
> > > > > > On Wed, Mar 06, 2019 at 11:22:53PM -0800, address@hidden wrote:
> > > > > > > diff --git a/docs/devel/qemu-multiprocess.txt b/docs/devel/qemu-multiprocess.txt
> > > > > > > new file mode 100644
> > > > > > > index 0000000..e29c6c8
> > > > > > > --- /dev/null
> > > > > > > +++ b/docs/devel/qemu-multiprocess.txt
> > > > > >
> > > > > > Thanks for this document and the interesting work that you are doing.
> > > > > > I'd like to discuss the security advantages gained by disaggregating
> > > > > > QEMU in more detail.
> > > > > >
> > > > > > The security model for VMs managed by libvirt (most production x86, ppc,
> > > > > > s390 guests) is that the QEMU process is untrusted and only has access
> > > > > > to resources belonging to the guest.  SELinux is used to restrict the
> > > > > > process from accessing other files, processes, etc on the host.
> > > > >
> > > > > NB it doesn't have to be SELinux. Libvirt also supports AppArmor and
> > > > > can even do isolation with traditional DAC by putting each QEMU under
> > > > > a distinct UID/GID and having libvirtd set ownership on resources each
> > > > > VM is permitted to use.
> > > > >
> > > > > > QEMU does not hold privileged resources that must be kept away from the
> > > > > > guest.  An escaped guest can access its image file, tap file descriptor,
> > > > > > etc but they are the same resources it could already access via device
> > > > > > emulation.
> > > > > >
> > > > > > Can you give specific examples of how disaggregation improves security?
> > > >
> > > > Elena & collaborators: Dan has posted some ideas but please share yours
> > > > so the security benefits of this patch series can be better understood.
> > >
> > >         Dan covered the main point.  The security regime we use (selinux)
> > > constrains the actions of processes on objects, so having multiple processes
> > > allows us to apply more fine-grained policies.
> >
> > Please share the SELinux policy files, containerization scripts, etc.
> > There is probably a home for them in qemu.git, libvirt.git, or elsewhere
> > upstream.
> >
> > We need to find a way to make the sandboxing improvements available to
> > users besides yourself and easily reusable for developers who wish to
> > convert additional device models.
>
> Ping?
>
> Without the scripts/policies there is no security benefit from this
> patch series.

Hi Stefan,

We are working on this. We'll get back to you once we have this
available.

Thanks!
--
Jag

> Stefan