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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 17E6EC47089 for ; Sat, 3 Dec 2022 02:35:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235172AbiLCCfE (ORCPT ); Fri, 2 Dec 2022 21:35:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52380 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235020AbiLCCfC (ORCPT ); Fri, 2 Dec 2022 21:35:02 -0500 Received: from mail-pj1-x1029.google.com (mail-pj1-x1029.google.com [IPv6:2607:f8b0:4864:20::1029]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89378E1769 for ; Fri, 2 Dec 2022 18:35:01 -0800 (PST) Received: by mail-pj1-x1029.google.com with SMTP id o12so6524605pjo.4 for ; Fri, 02 Dec 2022 18:35:01 -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=XQs9tVfGT9YvsTDVtvy9w4wMLhjzx69/QPDnzOH4S3c=; b=BdWCY0D6/wr/oO1soihVhNirwM62d3x+s0tgQ6bwd5Rj7JWEA/AE/XrfRopNOAwoz/ 05TXAjAuCW+vWbam1c1pbg13GCl4Mz1YtIeOJ4DYFu7vJpwyP3u/pJk7EQbmF1Fsbvxo IbSQDRCtw92dj9E+wfFDvqc9KGav6VtbWimEI= 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=XQs9tVfGT9YvsTDVtvy9w4wMLhjzx69/QPDnzOH4S3c=; b=FJyp2Fy1hnAtS0JdrQf3DWd1Z5s5oguwjPRHlOKGriCGV1CMou8cXnr2NPZUJWkOL2 cvWeYGZFoPBP4SIJkChibzKpwc6deuLwHxNqfqBp4sk/5GW6MClRCQ1EJkVR2LMiCjEM ddXJbwMjyU3WAW2pHUBITeQWgPEe1LMSIGOVzOFEYqLik9YVCJqWeGwMRWlz38gnjtv1 a0b5gF3VWnjxb7E9SLXO+UW/6UyBhTi6DAq3wYXYZqsSI8YnXL1wLfzz8yFzgZmHMfKe z9C/PtxKNRMl5HhdfSjBWaby6N8fIKStFVmqDLwPBYHryD5ExjkDdYuHwPvowOnv0ewq Egag== X-Gm-Message-State: ANoB5pnSuufQBT5X7JD81cmkbAJ9PHbtiJT8ksupTNGlYplGgABUJ8lW xldoDwbCh0EQdeTiN4qxxbWacQ== X-Google-Smtp-Source: AA0mqf7uStX3Ydoku6VU5WdR7aRvh89xtQi2ykwRpNP9wSfKDZaPCJnsBpzs/d7FPH3HpDywGEnbxA== X-Received: by 2002:a17:90a:5918:b0:213:df25:7e8a with SMTP id k24-20020a17090a591800b00213df257e8amr86239470pji.154.1670034901104; Fri, 02 Dec 2022 18:35:01 -0800 (PST) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id l12-20020a170902e2cc00b00176a6ba5969sm439650plc.98.2022.12.02.18.35.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 Dec 2022 18:35:00 -0800 (PST) Date: Fri, 2 Dec 2022 18:34:59 -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, Yu-cheng Yu Subject: Re: [PATCH v4 17/39] x86/mm: Update maybe_mkwrite() for shadow stack Message-ID: <202212021834.200AFA92BC@keescook> References: <20221203003606.6838-1-rick.p.edgecombe@intel.com> <20221203003606.6838-18-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221203003606.6838-18-rick.p.edgecombe@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Fri, Dec 02, 2022 at 04:35:44PM -0800, Rick Edgecombe wrote: > From: Yu-cheng Yu > > When serving a page fault, maybe_mkwrite() makes a PTE writable if there is > a write access to it, and its vma has VM_WRITE. Shadow stack accesses to > shadow stack vma's are also treated as write accesses by the fault handler. > This is because setting shadow stack memory makes it writable via some > instructions, so COW has to happen even for shadow stack reads. > > So maybe_mkwrite() should continue to set VM_WRITE vma's as normally > writable, but also set VM_WRITE|VM_SHADOW_STACK vma's as shadow stack. > > Do this by adding a pte_mkwrite_shstk() and a cross-arch stub. Check for > VM_SHADOW_STACK in maybe_mkwrite() and call pte_mkwrite_shstk() > accordingly. > > Apply the same changes to maybe_pmd_mkwrite(). > > Tested-by: Pengfei Xu > Tested-by: John Allen > Signed-off-by: Yu-cheng Yu Reviewed-by: Kees Cook -- Kees Cook