From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C786AC4321E for ; Sat, 3 Dec 2022 02:52:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6AB7E6B0071; Fri, 2 Dec 2022 21:52:35 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 681DC6B0072; Fri, 2 Dec 2022 21:52:35 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 523966B0073; Fri, 2 Dec 2022 21:52:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 4616D6B0071 for ; Fri, 2 Dec 2022 21:52:35 -0500 (EST) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 18B3B1A058C for ; Sat, 3 Dec 2022 02:52:35 +0000 (UTC) X-FDA: 80199471870.23.3611C67 Received: from mail-pj1-f51.google.com (mail-pj1-f51.google.com [209.85.216.51]) by imf03.hostedemail.com (Postfix) with ESMTP id B31CE20012 for ; Sat, 3 Dec 2022 02:52:34 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=G3PwPkkl; spf=pass (imf03.hostedemail.com: domain of keescook@chromium.org designates 209.85.216.51 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1670035954; a=rsa-sha256; cv=none; b=s3dbM5cGEoHHh5UId08bVZQ6lIrsAx9Kn+YlYpBEjQAAjGTj2hOKdjrxC6MWWgWXHae0Ca 83PwGOlxLT6ppyiT/SxJGqHh9LgWphymljU891DUaSqZGVHzo11724ADHSCd0KfRATuI7X Si+8OoQu7xe1Gs7r4GQEbDw4ljO7o/U= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=G3PwPkkl; spf=pass (imf03.hostedemail.com: domain of keescook@chromium.org designates 209.85.216.51 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1670035954; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=J6Bi98oKuxFWgcdJnIttlj0hQxwkrhCnC895Z7MBrPA=; b=pNiJCIUu3E1NcTlZ0EAUP6pmvn9jtOlDOQpineJzfbAgtyWfK+4u6lzi4aqqSZfeGPUOjn gKItHMJn+rtoMB/kPxkA5yL++8vyJHQwU8HLEh6ixBkMmePqu3+hN6FZ6f6791fBR2Kqiw rz8zs29QSuSYFt46EFqItaqX2cnCe9E= Received: by mail-pj1-f51.google.com with SMTP id o12so6545772pjo.4 for ; Fri, 02 Dec 2022 18:52:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=J6Bi98oKuxFWgcdJnIttlj0hQxwkrhCnC895Z7MBrPA=; b=G3PwPkklAW4vkncmaBzEMICopZp3Mv692M00zFs27IW9i/6mvm03dt//cegrsFawer Uk/v7oR2bXRlYn6JZTG6VV3/FgAq9tdCv4VQqbEryYFq1Zryqks//J9vOxjCDvTajMSL Cn3V/5fwZghyCOmIJ898KnniIOWpzz1R5ycFA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=J6Bi98oKuxFWgcdJnIttlj0hQxwkrhCnC895Z7MBrPA=; b=jPAQQbqQ9RCTnUaHcGgbA1Kg77MKw4VggTS94uDFi7bjSzAOZfbd6qGViSb2FS7Nnl tnBbWH0KJXptXhXVojuwXstFR14tkGT8pyPxrGB0w5yAGkg6mtdxI6wnYYFqb4UD+w2/ yEUF/WkV/EVZgscXKM92GByMvGXb5/tNreGmPJrHc/obA/bsoSI42t1zhHB9FsXK7kvd z3aUDLLUNI1K4VETx3PqsFD2HVClya59HdjrUwe/MGNjlWN27y/8H8Gfo5yE6PuS0snh hEGo9nMmJ8A38opVA50Ot4PFIELtrJuDMWTKgVv4tNflsRTwFayJ/E9PPJu2Bsoq2m0p HHKA== X-Gm-Message-State: ANoB5pltJ1Ij83Lu0/KZ2nouM1a1k7r5ni/Vzc/1eIStsODFhDHRmsMV gzGg1ClLhEsHSyLjqhvXZISFQw== X-Google-Smtp-Source: AA0mqf7wuueuka+zZZhnHrTJv5Bs8Z9bgUPy37YEHYzhG6WAxqMTnTK9X0leDnFE/fsw8X1YGvoPwg== X-Received: by 2002:a17:90a:5d05:b0:219:57e:7790 with SMTP id s5-20020a17090a5d0500b00219057e7790mr43217497pji.3.1670035953807; Fri, 02 Dec 2022 18:52:33 -0800 (PST) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id c194-20020a621ccb000000b0056d3b8f530csm5759664pfc.34.2022.12.02.18.52.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 Dec 2022 18:52:33 -0800 (PST) Date: Fri, 2 Dec 2022 18:52:32 -0800 From: Kees Cook To: Rick Edgecombe Cc: x86@kernel.org, "H . Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H . J . Lu" , Jann Horn , Jonathan Corbet , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , Weijiang Yang , "Kirill A . Shutemov" , John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com, akpm@linux-foundation.org, Andrew.Cooper3@citrix.com, christina.schimpe@intel.com Subject: Re: [PATCH v4 31/39] x86/shstk: Support wrss for userspace Message-ID: <202212021852.88C57CF544@keescook> References: <20221203003606.6838-1-rick.p.edgecombe@intel.com> <20221203003606.6838-32-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221203003606.6838-32-rick.p.edgecombe@intel.com> X-Spamd-Result: default: False [5.09 / 9.00]; SORBS_IRL_BL(3.00)[209.85.216.51:from]; SUSPICIOUS_RECIPS(1.50)[]; MID_RHS_NOT_FQDN(0.50)[]; RCVD_NO_TLS_LAST(0.10)[]; MIME_GOOD(-0.10)[text/plain]; BAD_REP_POLICIES(0.10)[]; BAYES_HAM(-0.01)[42.08%]; DKIM_TRACE(0.00)[chromium.org:+]; RCPT_COUNT_TWELVE(0.00)[38]; FROM_EQ_ENVFROM(0.00)[]; DMARC_POLICY_ALLOW(0.00)[chromium.org,none]; MIME_TRACE(0.00)[0:+]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; PREVIOUSLY_DELIVERED(0.00)[linux-mm@kvack.org]; R_DKIM_ALLOW(0.00)[chromium.org:s=google]; ARC_NA(0.00)[]; ARC_SIGNED(0.00)[hostedemail.com:s=arc-20220608:i=1]; FROM_HAS_DN(0.00)[]; R_SPF_ALLOW(0.00)[+ip4:209.85.128.0/17]; TO_DN_SOME(0.00)[]; TAGGED_RCPT(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[] X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: B31CE20012 X-Stat-Signature: zisww7er4abhcayhzbrn7kdrrxiemntp X-HE-Tag: 1670035954-270936 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Dec 02, 2022 at 04:35:58PM -0800, Rick Edgecombe wrote: > For the current shadow stack implementation, shadow stacks contents can't > easily be provisioned with arbitrary data. This property helps apps > protect themselves better, but also restricts any potential apps that may > want to do exotic things at the expense of a little security. > > The x86 shadow stack feature introduces a new instruction, wrss, which > can be enabled to write directly to shadow stack permissioned memory from > userspace. Allow it to get enabled via the prctl interface. > > Only enable the userspace wrss instruction, which allows writes to > userspace shadow stacks from userspace. Do not allow it to be enabled > independently of shadow stack, as HW does not support using WRSS when > shadow stack is disabled. > > From a fault handler perspective, WRSS will behave very similar to WRUSS, > which is treated like a user access from a #PF err code perspective. > > Tested-by: Pengfei Xu > Tested-by: John Allen > Signed-off-by: Rick Edgecombe Reviewed-by: Kees Cook -- Kees Cook