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[81.97.203.96]) by smtp.gmail.com with ESMTPSA id c7-20020adfe707000000b002bfb0c5527esm1555390wrm.109.2023.01.26.07.22.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Jan 2023 07:22:11 -0800 (PST) Date: Thu, 26 Jan 2023 15:22:09 +0000 From: "Dr. David Alan Gilbert" To: Richard Weinberger Cc: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , Greg Kroah-Hartman , "Reshetova, Elena" , "Shishkin, Alexander" , "Shutemov, Kirill" , "Kuppuswamy, Sathyanarayanan" , "Kleen, Andi" , "Hansen, Dave" , Thomas Gleixner , Peter Zijlstra , "Wunner, Lukas" , Mika Westerberg , "Michael S. Tsirkin" , Jason Wang , "Poimboe, Josh" , "aarcange@redhat.com" , Cfir Cohen , Marc Orr , "jbachmann@google.com" , "pgonda@google.com" , "keescook@chromium.org" , James Morris , Michael Kelley , "Lange, Jon" , "linux-coco@lists.linux.dev" , Linux Kernel Mailing List Subject: Re: Linux guest kernel threat model for Confidential Computing Message-ID: References: Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.2.9 (2022-11-12) X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit * Richard Weinberger (richard.weinberger@gmail.com) wrote: > On Thu, Jan 26, 2023 at 3:58 PM Dr. David Alan Gilbert > wrote: > > > > * Richard Weinberger (richard.weinberger@gmail.com) wrote: > > > On Wed, Jan 25, 2023 at 3:22 PM Daniel P. Berrangé 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. Yeh, that's not entirely crazy for VMs which tend to come off some remote storage system. > > 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. Hmm, OK, I'd assumed dm-crypt was OK since it's more hashlike and unchanging. Dave -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK