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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id s197sm20482307pfc.188.2020.06.24.08.45.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jun 2020 08:45:48 -0700 (PDT) Date: Wed, 24 Jun 2020 08:45:47 -0700 From: Kees Cook To: Ard Biesheuvel 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-Disposition: inline In-Reply-To: X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , linux-arch , linux-efi , Arnd Bergmann , Fangrui Song , Peter Collingbourne , Catalin Marinas , Masahiro Yamada , X86 ML , Nick Desaulniers , Russell King , Linux Kernel Mailing List , clang-built-linux , Arvind Sankar , Ingo Molnar , James Morse , Thomas Gleixner , Borislav Petkov , Will Deacon , Nathan Chancellor , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel