Re: Linux guest kernel threat model for Confidential Computing

Richard Weinberger
2023-01-26T15:13:26Z

On Thu, Jan 26, 2023 at 3:58 PM Dr. David Alan Gilbert
<dgilbert@redhat.com> wrote:
>
> * Richard Weinberger (richard.weinberger@gmail.com) wrote:
> > On Wed, Jan 25, 2023 at 3:22 PM Daniel P. Berrangé <berrange@redhat.com> wrote:
> > > Any virtual device exposed to the guest that can transfer potentially
> > > sensitive data needs to have some form of guest controlled encryption
> > > applied. For disks this is easy with FDE like LUKS, for NICs this is
> > > already best practice for services by using TLS. Other devices may not
> > > have good existing options for applying encryption.
> >
> > I disagree wrt. LUKS. The cryptography behind LUKS protects persistent data
> > but not transport. If an attacker can observe all IO you better
> > consult a cryptographer.
> > LUKS has no concept of session keys or such, so the same disk sector will
> > always get encrypted with the very same key/iv.
>
> Are you aware of anything that you'd use instead?

Well, I'd think towards iSCSI over TLS to protect the IO transport.

> Are you happy with dm-verity for protection against modification?

Like LUKS (actually dm-crypt) the crypto behind is designed to protect
persistent data not transport.
My fear is that an attacker who is able to observe IOs can do bad things.