From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Subject: Re: [PATCH v3 3/9] efi/libstub: Remove .note.gnu.property Date: Wed, 24 Jun 2020 08:45:47 -0700 Message-ID: <202006240844.7BE48D2B5@keescook> References: <20200624014940.1204448-1-keescook@chromium.org> <20200624014940.1204448-4-keescook@chromium.org> <20200624033142.cinvg6rbg252j46d@google.com> <202006232143.66828CD3@keescook> <20200624104356.GA6134@willie-the-truck> <202006240820.A3468F4@keescook> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404341AbgFXPpu (ORCPT ); Wed, 24 Jun 2020 11:45:50 -0400 Received: from mail-pg1-x543.google.com (mail-pg1-x543.google.com [IPv6:2607:f8b0:4864:20::543]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 23294C061795 for ; Wed, 24 Jun 2020 08:45:50 -0700 (PDT) Received: by mail-pg1-x543.google.com with SMTP id s10so1617355pgm.0 for ; Wed, 24 Jun 2020 08:45:50 -0700 (PDT) Content-Disposition: inline In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Ard Biesheuvel Cc: Will Deacon , Fangrui Song , Catalin Marinas , Mark Rutland , Peter Collingbourne , James Morse , Borislav Petkov , Thomas Gleixner , Ingo Molnar , Russell King , Masahiro Yamada , Arvind Sankar , Nick Desaulniers , Nathan Chancellor , Arnd Bergmann , X86 ML , clang-built-linux , linux-arch , linux-efi , Linux ARM On Wed, Jun 24, 2020 at 05:31:06PM +0200, Ard Biesheuvel wrote: > On Wed, 24 Jun 2020 at 17:21, Kees Cook wrote: > > > > On Wed, Jun 24, 2020 at 12:46:32PM +0200, Ard Biesheuvel wrote: > > > I'm not sure if there is a point to having PAC and/or BTI in the EFI > > > stub, given that it runs under the control of the firmware, with its > > > memory mappings and PAC configuration etc. > > > > Is BTI being ignored when the firmware runs? > > Given that it requires the 'guarded' attribute to be set in the page > tables, and the fact that the UEFI spec does not require it for > executables that it invokes, nor describes any means of annotating > such executables as having been built with BTI annotations, I think we > can safely assume that the EFI stub will execute with BTI disabled in > the foreseeable future. yaaaaaay. *sigh* How long until EFI catches up? That said, BTI shouldn't _hurt_, right? If EFI ever decides to enable it, we'll be ready? -- Kees Cook From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404341AbgFXPpu (ORCPT ); Wed, 24 Jun 2020 11:45:50 -0400 Received: from mail-pg1-x543.google.com (mail-pg1-x543.google.com [IPv6:2607:f8b0:4864:20::543]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 23294C061795 for ; Wed, 24 Jun 2020 08:45:50 -0700 (PDT) Received: by mail-pg1-x543.google.com with SMTP id s10so1617355pgm.0 for ; Wed, 24 Jun 2020 08:45:50 -0700 (PDT) Date: Wed, 24 Jun 2020 08:45:47 -0700 From: Kees Cook Subject: Re: [PATCH v3 3/9] efi/libstub: Remove .note.gnu.property Message-ID: <202006240844.7BE48D2B5@keescook> References: <20200624014940.1204448-1-keescook@chromium.org> <20200624014940.1204448-4-keescook@chromium.org> <20200624033142.cinvg6rbg252j46d@google.com> <202006232143.66828CD3@keescook> <20200624104356.GA6134@willie-the-truck> <202006240820.A3468F4@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Ard Biesheuvel Cc: Will Deacon , Fangrui Song , Catalin Marinas , Mark Rutland , Peter Collingbourne , James Morse , Borislav Petkov , Thomas Gleixner , Ingo Molnar , Russell King , Masahiro Yamada , Arvind Sankar , Nick Desaulniers , Nathan Chancellor , Arnd Bergmann , X86 ML , clang-built-linux , linux-arch , linux-efi , Linux ARM , Linux Kernel Mailing List Message-ID: <20200624154547.ofSExHwimfFeF6O5tv_g_BN9BzsSgREAl0lq4Lfw8tc@z> On Wed, Jun 24, 2020 at 05:31:06PM +0200, Ard Biesheuvel wrote: > On Wed, 24 Jun 2020 at 17:21, Kees Cook wrote: > > > > On Wed, Jun 24, 2020 at 12:46:32PM +0200, Ard Biesheuvel wrote: > > > I'm not sure if there is a point to having PAC and/or BTI in the EFI > > > stub, given that it runs under the control of the firmware, with its > > > memory mappings and PAC configuration etc. > > > > Is BTI being ignored when the firmware runs? > > Given that it requires the 'guarded' attribute to be set in the page > tables, and the fact that the UEFI spec does not require it for > executables that it invokes, nor describes any means of annotating > such executables as having been built with BTI annotations, I think we > can safely assume that the EFI stub will execute with BTI disabled in > the foreseeable future. yaaaaaay. *sigh* How long until EFI catches up? That said, BTI shouldn't _hurt_, right? If EFI ever decides to enable it, we'll be ready? -- Kees Cook