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 5650AC433FE for ; Mon, 3 Oct 2022 18:23:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229781AbiJCSXB (ORCPT ); Mon, 3 Oct 2022 14:23:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48194 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229669AbiJCSW5 (ORCPT ); Mon, 3 Oct 2022 14:22:57 -0400 Received: from mail-pf1-x434.google.com (mail-pf1-x434.google.com [IPv6:2607:f8b0:4864:20::434]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B7D8A2F028 for ; Mon, 3 Oct 2022 11:22:54 -0700 (PDT) Received: by mail-pf1-x434.google.com with SMTP id 83so3910705pfw.10 for ; Mon, 03 Oct 2022 11:22:54 -0700 (PDT) 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; bh=DpamCQg4r6DJ9TEvfJUx5RfmiJZUBbQ1vJaFAYMtbtE=; b=bKitYN0ycfUP50dLE5yBs9aVB69jVdFmdIDNWZSSiBtQ2XyHoGDEf5LYIZa1I/OwhF 1fu8VI8iw+wr2lMK3sdEZx7+Gt162AqNHmK5PBQuBSw+CUdTXUH9di6lhhM8m5g4r6ni Cf/ac/CiSEYQJtBC8L2idRWiSX6thxVOEH5Tg= 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; bh=DpamCQg4r6DJ9TEvfJUx5RfmiJZUBbQ1vJaFAYMtbtE=; b=oE4X6CnEzjQeE677vOXtrE8ZSau/x1Zj4SSehdUTcjfJJfJuFAZARs/x4dWOqhxIec wBRZo7l6bqSW6VaEY2GztgIzadQjRzh5VrtDewav/cN6G4hpDrhBPQLVKlpCsMRwn2Va 8Y/k3HovgJ49D/fuUoAU/i2d+1583eZsa3tw1Dp1ylFURGLU6nJS/IQnEMmxD4MBEUC7 LYnGl4CYnSYN7DdO7hfaW9GzZO9esU05iSwWriI5WBcY0SEuwJFZaYmjo/EqSzRY3kYh Q8APc/qDJtIlQ4Qv/7VkY0hfKfrCRGjuCb0OZyJ79oPc6Ou+BJl+9WNhvI3pwckkHL53 EEbQ== X-Gm-Message-State: ACrzQf3Vko/xLUC2qzjab4cV6Vn2TWSt9uhDb8XbM+fJsYSrPu2MK4u7 I8ezNT19HRHVUZ2HrtIklCyNRQ== X-Google-Smtp-Source: AMsMyM7dTP6DXvLNUcsKmzIg6k7/Qu8IfrWs3YPR/Fd2tS7bSA3q/wwAl34jCHU6wmwWuCw+ROg+Fw== X-Received: by 2002:a05:6a00:2185:b0:520:7276:6570 with SMTP id h5-20020a056a00218500b0052072766570mr23927389pfi.84.1664821374239; Mon, 03 Oct 2022 11:22:54 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id h4-20020a170902f54400b0017ee7f331ffsm3242061plf.291.2022.10.03.11.22.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Oct 2022 11:22:53 -0700 (PDT) Date: Mon, 3 Oct 2022 11:22:52 -0700 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 , "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, Yu-cheng Yu Subject: Re: [PATCH v2 16/39] x86/mm: Update maybe_mkwrite() for shadow stack Message-ID: <202210031122.A27CE24D39@keescook> References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-17-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220929222936.14584-17-rick.p.edgecombe@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 29, 2022 at 03:29:13PM -0700, 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(). > > Signed-off-by: Yu-cheng Yu Reviewed-by: Kees Cook -- Kees Cook