Re: Support status of OpenBSD frontend drivers

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On Thu, Mar 24, 2022 at 11:49:14AM -0400, Demi Marie Obenour wrote:
> On 3/24/22 10:11, Roger Pau Monné wrote:
> > On Thu, Mar 24, 2022 at 09:56:29AM -0400, Demi Marie Obenour wrote:
> >> As per private discussion with Theo de Raadt, OpenBSD does not consider
> >> bugs in its xnf(4) that allow a backend to cause mischief to be security
> >> issues.  I believe the same applies to its xbf(4).  Should the support
> >> document be updated?
> > 
> > I think that's already reflected in the support document:
> > 
> > 'Status, OpenBSD: Supported, Security support external'
> > 
> > Since the security support is external it's my understanding OpenBSD
> > security team gets to decide what's a security issue and what is not.
> > 
> > That however creates differences in the level of support offered by
> > the different OSes, but I think that's unavoidable. It's also hard to
> > track the status here because those are external components in
> > separate code bases.
> > 
> > Could be added as a mention together with the Windows note about
> > frontends trusting backends, but then I would fear this is likely to
> > get out of sync if OpenBSD ever changes their frontends to support
> > untrusted backends (even if not considered as a security issue).
> 
> As a Qubes OS developer, I still think this is useful information and
> should be documented.  For instance, if I choose to add proper OpenBSD
> guest support to Qubes OS (as opposed to the current “you can run
> anything in an HVM” situation), I might decide to have OpenBSD
> guests use devices emulated by a Linux-based stubdomain, since the
> stubdomain’s netfront and blkfront drivers *are* security-supported
> against malicious backends.  I might also choose to have a warning in
> the GUI when switching the NetVM of an OpenBSD guest to something other
> than the empty string (meaning no network access) or the (normally
> fairly trusted) sys-firewall or sys-whonix qubes.

I'm with Roger on this - when security support is external, such
information in xen.git could easily become stale. If anything, there
could be a link to OpenBSD security status info, maintained by whoever
such support provides.

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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