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 X-Spam-Level: X-Spam-Status: No, score=-11.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A45BEC433E9 for ; Thu, 4 Feb 2021 20:23:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4D5C964E0A for ; Thu, 4 Feb 2021 20:23:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238754AbhBDUW7 (ORCPT ); Thu, 4 Feb 2021 15:22:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45656 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240071AbhBDUWu (ORCPT ); Thu, 4 Feb 2021 15:22:50 -0500 Received: from mail-pg1-x533.google.com (mail-pg1-x533.google.com [IPv6:2607:f8b0:4864:20::533]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D3748C06178A for ; Thu, 4 Feb 2021 12:22:15 -0800 (PST) Received: by mail-pg1-x533.google.com with SMTP id r38so2885872pgk.13 for ; Thu, 04 Feb 2021 12:22:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=wnU2ljW3GZfVnC0yk4dz3F0Y7a+z0DVuakcSpmImkaw=; b=gk1+3E6zusffn9W5IuwsN3M705pg/AsgpNvWYuk60I9SgeXKbvb/YqudopHfguTWg9 XHcDS3MQ5Ux9oTwks1PbxMjwOQxFmmNtlcxRxjcKXwBpL+AypZgWkafkkCYlZNNC8R7x wPriOS6bS/ExEs3s+CHTQ9aBYRWxITrDlxn9s= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=wnU2ljW3GZfVnC0yk4dz3F0Y7a+z0DVuakcSpmImkaw=; b=NzVSNXgXUYPP3419vDC0g82cGhiIrecMdPH5BRj6KHv2Ehj04TWvt48laWpd4csN7S c3W+nmkC0JyamfbCpZJV9STIoktP/57ymUxj09I03Jk2Wt31Q3/NLiPa925hDjtRbbAn BcMhmqAr8gmur2MTsIlOcJrOp8VIqteAr3jiy3sERa6UII/uPhlr75JyVrn2Yxx5UYhO SKe/7OPSBDsFtkMF9YJj0lNZMxEfwwf/Au1B1AfW4CaUCEIwlPz+zOPw/bO2c6ynyQde AAUsGUkVKsusx5oI8cptfzDvIzvlg1O4n4qfXBB9XjwH6hOAhk44DexfcqpQmtiWBHPn HijQ== X-Gm-Message-State: AOAM532tCaSUPxUshHRKederx873trtmPK+3Abq984CZj7Dmw8Q2hcwv lHzAgqM9EoBlzLjJdRByASPtzg== X-Google-Smtp-Source: ABdhPJxQWfp/aPzc5XZSKfbRPLKD5pttOTUDGoXyRh6jr8ntSfLzFQ6LjNTCdQXVJDDoi4XbHDHR4A== X-Received: by 2002:a63:5952:: with SMTP id j18mr708407pgm.29.1612470135501; Thu, 04 Feb 2021 12:22:15 -0800 (PST) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id 11sm7480618pgz.22.2021.02.04.12.22.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Feb 2021 12:22:14 -0800 (PST) Date: Thu, 4 Feb 2021 12:22:13 -0800 From: Kees Cook To: Yu-cheng Yu 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" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu Subject: Re: [PATCH v19 14/25] x86/mm: Update maybe_mkwrite() for shadow stack Message-ID: <202102041222.B111A20A9@keescook> References: <20210203225547.32221-1-yu-cheng.yu@intel.com> <20210203225547.32221-15-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210203225547.32221-15-yu-cheng.yu@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Wed, Feb 03, 2021 at 02:55:36PM -0800, Yu-cheng Yu wrote: > When serving a page fault, maybe_mkwrite() makes a PTE writable if its vma > has VM_WRITE. > > A shadow stack vma has VM_SHSTK. Its PTEs have _PAGE_DIRTY, but not > _PAGE_WRITE. In fork(), _PAGE_DIRTY is cleared to effect copy-on-write, > and in page fault, _PAGE_DIRTY is restored and the shadow stack page is > writable again. > > Update maybe_mkwrite() by introducing arch_maybe_mkwrite(), which sets > _PAGE_DIRTY for a shadow stack PTE. > > Apply the same changes to maybe_pmd_mkwrite(). > > Signed-off-by: Yu-cheng Yu Reviewed-by: Kees Cook -- Kees Cook