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 49EBDC433FE for ; Mon, 3 Oct 2022 18:39:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229735AbiJCSjR (ORCPT ); Mon, 3 Oct 2022 14:39:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46936 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229709AbiJCSjO (ORCPT ); Mon, 3 Oct 2022 14:39:14 -0400 Received: from mail-pg1-x52a.google.com (mail-pg1-x52a.google.com [IPv6:2607:f8b0:4864:20::52a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 88D763ED6A for ; Mon, 3 Oct 2022 11:39:12 -0700 (PDT) Received: by mail-pg1-x52a.google.com with SMTP id e129so10369916pgc.9 for ; Mon, 03 Oct 2022 11:39:12 -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=G7bUMV+FEZy7kwIPvofvWVHEzM2JjGpJ/T9cn7FANKI=; b=DbL7LAsMn1ZPP3tNqgEAs3OQijAthjiTsME8iEq9bYxYCoSv0lX69AAmGW/K9A6j/q TMxBNDTbCnI8kpn+gp3mX8N+xIP0/vXpRvy2NYb976KpDaLB/bkmYwScsJ09vfjp9jgi P5XvS/Lge/4CLPDX9IZNvy8a9fJitWxxwmk0E= 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=G7bUMV+FEZy7kwIPvofvWVHEzM2JjGpJ/T9cn7FANKI=; b=mK9HuK0JSle8Ouyp/iAsGcRmOIeST+l/OdyJNBO/7OAHns86uI6Z3U4OqYDVwsnMqy X/ZlWFOhiNJca7KSfvpI2ydbLliT5pWpGyzs1cmdvknEHE39ery/6OLg/FrOW2O3kjPj E6pt9+EvZQlhGtor+F3OaWTG6IiDni7Y0Ao4xPC3dt6Z8VP4hDA5fFJcWzkmui5PA4nc iERzQ4xju63hfW18yKPIR8pJONZsMvYc9vcSOHnbb+Fg8PG8VazqkfT//I0p8ZZ90snx 7I774LhDVYoNe5NhmxX7x903fHkp75Hmeb19b7st74b417s/q4X9/90h4z6Ygf5u3UB1 PbMw== X-Gm-Message-State: ACrzQf3NXn10wrhixJXifywiqCgBByi6XYFDorvUS8uxmZ7tXc2/HqxH eA/MA0ermWTw3qcM8+Q6SxsEiw== X-Google-Smtp-Source: AMsMyM7dhnU1K9hukcn95YVuWGVu5LA5Bt+XPOoY3OKL7aWIGI8OTGW3VT2EJsGjF80hrfyoCag0wQ== X-Received: by 2002:a62:1482:0:b0:55f:eb9a:38b2 with SMTP id 124-20020a621482000000b0055feb9a38b2mr11535532pfu.29.1664822351896; Mon, 03 Oct 2022 11:39:11 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id v62-20020a626141000000b0054097cb2da6sm7726006pfb.38.2022.10.03.11.39.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Oct 2022 11:39:11 -0700 (PDT) Date: Mon, 3 Oct 2022 11:39:10 -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 Subject: Re: [PATCH v2 22/39] mm: Don't allow write GUPs to shadow stack memory Message-ID: <202210031134.B0B6B37@keescook> References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-23-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220929222936.14584-23-rick.p.edgecombe@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 29, 2022 at 03:29:19PM -0700, Rick Edgecombe wrote: > [...] > Still allow FOLL_FORCE to write through shadow stack protections, as it > does for read-only protections. As I asked in the cover letter: why do we need to add this for shstk? It was a mistake for general memory. :P > [...] > diff --git a/mm/gup.c b/mm/gup.c > index 5abdaf487460..56da98f3335c 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1043,7 +1043,7 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags) > return -EFAULT; > > if (write) { > - if (!(vm_flags & VM_WRITE)) { > + if (!(vm_flags & VM_WRITE) || (vm_flags & VM_SHADOW_STACK)) { > if (!(gup_flags & FOLL_FORCE)) > return -EFAULT; > /* How about this instead: return -EFAULT; if (write) { + if (vm_flags & VM_SHADOW_STACK) + return -EFAULT; if (!(vm_flags & VM_WRITE)) { if (!(gup_flags & FOLL_FORCE)) return -EFAULT; -- Kees Cook