Re: Support status of OpenBSD frontend drivers

[Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>]

On 3/24/22 18:21, Marek Marczykowski-Górecki wrote:
> 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.

This ought to be on https://man.openbsd.org/xnf.4 and
https://man.openbsd.org/xbf.4, but it is not.  Should I send a patch?
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab

Attachment: OpenPGP_0xB288B55FFF9C22C1.asc
Description: OpenPGP public key

Attachment: OpenPGP_signature
Description: OpenPGP digital signature