On Friday 15 April 2016 09:47:51 Eric Blake wrote:
On 04/15/2016 04:41 AM, Cole Robinson wrote:
> Libvirt currently rejects using host /dev/urandom as an input source
> for a virtio-rng device. The only accepted sources are /dev/random
> and /dev/hwrng. This is the result of discussions on qemu-devel
> around when the feature was first added (2013). Examples:
>
>
http://lists.gnu.org/archive/html/qemu-devel/2012-09/msg02387.html
>
https://lists.gnu.org/archive/html/qemu-devel/2013-03/threads.html#0
> 0023
>
> libvirt's rejection of /dev/urandom has generated some complaints
> from users:
>
>
https://bugzilla.redhat.com/show_bug.cgi?id=1074464
> * cited:
http://www.2uo.de/myths-about-urandom/
>
http://www.redhat.com/archives/libvir-list/2016-March/msg01062.html
>
http://www.redhat.com/archives/libvir-list/2016-April/msg00186.html
>
> I think it's worth having another discussion about this, at least
> with a recent argument in one place so we can put it to bed. I'm
> CCing a bunch of people. I think the questions are:
>
> 1) is the original recommendation to never use
> virtio-rng+/dev/urandom correct?
That I'm not sure about - and the answer may be context-dependent (for
example a FIPS user may care more than an ordinary user)
/dev/urandom use is FIPS compliant, no FIPS-validated protocol or
cryptographic primitive requires the "fresh" entropy provided by
/dev/random. All primitives are designed to work with weaker entropy
guarantees than what /dev/urandom provides.
--
Regards,
Hubert Kario
Senior Quality Engineer, QE BaseOS Security team
Web:
www.cz.redhat.com
Red Hat Czech s.r.o., Purkyňova 99/71, 612 45, Brno, Czech Republic