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 64672C433FE for ; Mon, 3 Oct 2022 23:00:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D68796B0071; Mon, 3 Oct 2022 19:00:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D18A06B0073; Mon, 3 Oct 2022 19:00:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BE1796B0074; Mon, 3 Oct 2022 19:00:42 -0400 (EDT) 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 ABDD36B0071 for ; Mon, 3 Oct 2022 19:00:42 -0400 (EDT) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 841E1140AA2 for ; Mon, 3 Oct 2022 23:00:42 +0000 (UTC) X-FDA: 79981159524.18.D679D7A Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf02.hostedemail.com (Postfix) with ESMTP id 8331D8000F for ; Mon, 3 Oct 2022 23:00:41 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 00956B8164A; Mon, 3 Oct 2022 23:00:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E96D1C433D6; Mon, 3 Oct 2022 23:00:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664838038; bh=Xkf3Bl/hAOuHkGitFzqAuKe/IKE2LWmGABmXb5OtS5M=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=ikeZ4d26/rwOgesKbWVRO5wEoNTErR8LHHqKYkqW75cxZ1L3X1Wb7zX/m+V6jJeE5 +Ylgz6sIK59ufis/31nPNEZNAlekaVtR2zkRw0CkCRZfy4bsRk13JFNkkc+KwAThhO dtLyV/4iJdS90xMYqz8adnepkLgDq0kshRpG7ibCfhF+6myF9Sw5/XSgAYM0S6xWnM 8u3rQxFXCbyuj8fPOkeWedRr29AfZkUcrIANSNqteraG/IJaRnXbOq/BpC15Be5x2N xoxdEknCqggH1GgSRCv2U0DT26v+pHt8w2QDOXtx20ulLrlZyp40wK3sgdsTmjOO+4 r8WWRvahIoE2A== Message-ID: <6ea0841f-5086-9569-028b-922ec01a9196@kernel.org> Date: Mon, 3 Oct 2022 16:00:36 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.12.0 Subject: Re: [PATCH v2 29/39] x86/cet/shstk: Support wrss for userspace Content-Language: en-US To: Kees Cook , 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 , 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 , "Ravi V . Shankar" , Weijiang Yang , "Kirill A . Shutemov" , joao.moreira@intel.com, John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-30-rick.p.edgecombe@intel.com> <202210031525.78F3FA8@keescook> From: Andy Lutomirski In-Reply-To: <202210031525.78F3FA8@keescook> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1664838041; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=0sSnz3reJkzpZvYlxI0AP37k5VJHi8ZVSD5CQUajKUY=; b=o8XA4pPNUPBjVIHID9KgKdbQlWExOgHmA1QSvpZB1NHDH/dMNM2b4QMYvJ6nmzz2x9IcTf f8/TE2VKQMZp2P9WNe9EO/EX7xD5XtPG+6Pm2QpisPt9PNF29VYQ2y7SB30kZBvW6OVPRG 7C8Wmx0vAVA/RGN6/kgyvkx/IAaX15k= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=ikeZ4d26; spf=pass (imf02.hostedemail.com: domain of luto@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=luto@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1664838041; a=rsa-sha256; cv=none; b=PuJaD2o2ZaKc5+rW1QjyMLUJz4Y2k1Hjy3m8pBjh2GJoCZpUnnQP46ZmQ2xPUH6BVumZrg G+eStS3JUP4G4JfRt6Fe3EGHRBmIANvOPhxk8ZA4+6FzUBR6ndVpJW5fyZAA2yA3EbQs0+ H1JvUkcNtM87oMg3M1ECPBQ42rwStKU= Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=ikeZ4d26; spf=pass (imf02.hostedemail.com: domain of luto@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=luto@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 8331D8000F X-Rspam-User: X-Stat-Signature: em3ugo6pf8k4s1jtz46943k57d5pchwa X-HE-Tag: 1664838041-527982 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 10/3/22 15:28, Kees Cook wrote: > On Thu, Sep 29, 2022 at 03:29:26PM -0700, Rick Edgecombe wrote: >> For the current shadow stack implementation, shadow stacks contents easily >> be arbitrarily provisioned with data. > > I can't parse this sentence. > >> 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. > > Is anything using this right now? Wouldn't thing be safer without WRSS? > (Why can't we skip this patch?) > So that people don't write programs that need either (shstk off) or (shstk on and WRSS on) and crash or otherwise fail on kernels that support shstk but don't support WRSS, perhaps?