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From:   Richard Weinberger <richard.weinberger@gmail.com>
Date:   Thu, 26 Jan 2023 15:23:34 +0100
Message-ID: <CAFLxGvwHRK3vyXiCv5ELvrDSEkcDgV5c6pNnWgWhcATfp1dedA@mail.gmail.com>
Subject: Re: Linux guest kernel threat model for Confidential Computing
To:     =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?= <berrange@redhat.com>
Cc:     "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Reshetova, Elena" <elena.reshetova@intel.com>,
        "Shishkin, Alexander" <alexander.shishkin@intel.com>,
        "Shutemov, Kirill" <kirill.shutemov@intel.com>,
        "Kuppuswamy, Sathyanarayanan" <sathyanarayanan.kuppuswamy@intel.com>,
        "Kleen, Andi" <andi.kleen@intel.com>,
        "Hansen, Dave" <dave.hansen@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        "Wunner, Lukas" <lukas.wunner@intel.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        "Poimboe, Josh" <jpoimboe@redhat.com>,
        "aarcange@redhat.com" <aarcange@redhat.com>,
        Cfir Cohen <cfir@google.com>, Marc Orr <marcorr@google.com>,
        "jbachmann@google.com" <jbachmann@google.com>,
        "pgonda@google.com" <pgonda@google.com>,
        "keescook@chromium.org" <keescook@chromium.org>,
        James Morris <jmorris@namei.org>,
        Michael Kelley <mikelley@microsoft.com>,
        "Lange, Jon" <jlange@microsoft.com>,
        "linux-coco@lists.linux.dev" <linux-coco@lists.linux.dev>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Wed, Jan 25, 2023 at 3:22 PM Daniel P. Berrang=C3=A9 <berrange@redhat.co=
m> 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.

--=20
Thanks,
//richard