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From:   Richard Weinberger <richard.weinberger@gmail.com>
Date:   Thu, 26 Jan 2023 16:13:11 +0100
Message-ID: <CAFLxGvyMncqjkEXiOqenQu+rZW46RP7UorXs36+awmgnBxTGhA@mail.gmail.com>
Subject: Re: Linux guest kernel threat model for Confidential Computing
To:     "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc:     =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?= <berrange@redhat.com>,
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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. Berrang=C3=A9 <berrange@redha=
t.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 no=
t
> > > 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 wi=
ll
> > 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.