From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7AA714C8E for ; Wed, 26 Apr 2023 16:03:31 +0000 (UTC) Received: by mail-yb1-f201.google.com with SMTP id 3f1490d57ef6-b9a1f3b283bso2646822276.1 for ; Wed, 26 Apr 2023 09:03:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1682525010; x=1685117010; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=1iOXlTlBLlGt+xFnlJYCk9LyE8NZedUUmTtvF/W7cl8=; b=h+7lAviaHcHoFJpqy3l+q4CabqtBWTwMXj6h3C+ydRYC7L5NH31UBwdxn/KILMf1vm Y3vhdFcyJJxaJBnjdPnWm7EBsjBS8kuNRT0+c+ooFTlTSiIAeM+ZhPZ+v4avFK2rF6da NKHHFZS93BeoFnmnVNHb70DY2nYMrEXtIMaEcvAzh9FEsQlC+lu4UZrSdQJNIi3TbNiN Osqj2HWbJV565qJluzmWFQ2Zx94MqcPWBMekVUXkmQ0ynAuX+95+bgjNZRWPsXuaW3gU EXWxsZ29GFTlMsTaKN2ZOqlgY92cP9ECTwdj+vbRvLIyJcH5f/MnuTDBzk0s/4Dcuuor UogA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682525010; x=1685117010; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=1iOXlTlBLlGt+xFnlJYCk9LyE8NZedUUmTtvF/W7cl8=; b=fNocYVcmKO04WC2F/E2SZLmNsrV/QJoakWzx0JiRvQUCCThbvD1Ll4iZTHc1ur9htu bcofU8321rb9BSWyDjR/aLpycuNxhXMmuUjCdeD9X0sFeYJsIWHKnrracqnE00cs1jkX OX5OHmcME14m1PUj+8jbZEaLXnZtWEHKThJljdKlfim5UpMHfIyTxgf9RQnypnHLdMod RRiAnHJ2DeaZ1ecP8JcLSeRv1r72cPacINKjSyFWhEPhpXirp+qDPNAblixhGHuiE1ze Nozlz+FsgkdYe+KC3v8l51HloepfTPRJ/SBu7dLc5LxcVYmhxeNpIYq9cs+/I2ouKENp mrRA== X-Gm-Message-State: AAQBX9elgq5XpiO/GwbFKCveS+CYfnqERx+ZHjt587cC+MNc07Piiuwm 2E3th6Be8duROH0Hc+d8SDxNfqh6x4E= X-Google-Smtp-Source: AKy350bLi2qJ+4nzU1ANPOt2oieWNNI6eHJyZmf0N2WaN8R6KPw5aRqvu3QGqGyegbPKHISQlL/Sdaz4cD4= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:cac4:0:b0:b8f:1d2c:243f with SMTP id a187-20020a25cac4000000b00b8f1d2c243fmr7979508ybg.1.1682525010384; Wed, 26 Apr 2023 09:03:30 -0700 (PDT) Date: Wed, 26 Apr 2023 09:03:28 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20230327141816.2648615-1-carlos.bilbao@amd.com> Message-ID: Subject: Re: [PATCH] docs: security: Confidential computing intro and threat model From: Sean Christopherson To: Dave Hansen Cc: Carlos Bilbao , corbet@lwn.net, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, ardb@kernel.org, kraxel@redhat.com, dovmurik@linux.ibm.com, elena.reshetova@intel.com, dave.hansen@linux.intel.com, Dhaval.Giani@amd.com, michael.day@amd.com, pavankumar.paluri@amd.com, David.Kaplan@amd.com, Reshma.Lal@amd.com, Jeremy.Powell@amd.com, sathyanarayanan.kuppuswamy@linux.intel.com, alexander.shishkin@linux.intel.com, thomas.lendacky@amd.com, tglx@linutronix.de, dgilbert@redhat.com, gregkh@linuxfoundation.org, dinechin@redhat.com, linux-coco@lists.linux.dev, berrange@redhat.com, mst@redhat.com, tytso@mit.edu, jikos@kernel.org, joro@8bytes.org, leon@kernel.org, richard.weinberger@gmail.com, lukas@wunner.de, jejb@linux.ibm.com, cdupontd@redhat.com, jasowang@redhat.com, sameo@rivosinc.com, bp@alien8.de, security@kernel.org Content-Type: text/plain; charset="us-ascii" On Wed, Apr 26, 2023, Dave Hansen wrote: > On 4/25/23 08:02, Sean Christopherson wrote: > >> +While the traditional hypervisor has unlimited access to guest data and > >> +can leverage this access to attack the guest, the CoCo systems mitigate > >> +such attacks by adding security features like guest data confidentiality > >> +and integrity protection. This threat model assumes that those features > >> +are available and intact. > > Again, if you're claiming integrity is a key tenant, then SEV and SEV-ES can't be > > considered CoCo. > > This document is clearly trying to draw a line in the sand and say: > > CoCo on one side, non-CoCo on the other > > I think it's less important to name that line than it is to realize what > we need to do on one side versus the other. > > For instance, if the system doesn't have strong guest memory > confidentiality protection, then it's kinda silly to talk about the > guest's need to defend against "CoCo guest data attacks". > > Sure, the mitigations for "CoCo guest data attacks" are pretty sane even > without all this CoCo jazz. But if your goal is to mitigate damage that > a VMM out of the TCB can do, then they don't do much if there isn't > VMM->guest memory confidentiality in the first place. > > So, sure, CoCo implementations exist along a continuum. SGX is in there > (with and without integrity protection), as are SEV=>SEV-ES=>SEV and > MKTME=>TDX. > > This document is making the case that the kernel should go to some new > (and extraordinary) lengths to defend itself against ... something. Then name the document something other than confidential-computing.rst, e.g. tdx-and-snp-threat-model.rst. Because this doc isn't remotely close to achieving its stated goal of providing an "architecture-agnostic introduction ... to help developers gain a foundational understanding of the subject". IMO, it does more harm than good on that front because it presents Intel's and AMD's viewpoints as if they are widely accepted for all of CoCo, and that is just flagrantly false. : In order to effectively engage with the linux-coco mailing list and contribute : to ongoing kernel efforts, one must have a thorough familiarity with these : concepts. Add a concise, architecture-agnostic introduction and threat model : to provide a reference for ongoing design discussions and to help developers : gain a foundational understanding of the subject.