From patchwork Fri May 19 21:26:34 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rik van Riel X-Patchwork-Id: 9738215 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id D659F6041F for ; Fri, 19 May 2017 21:35:17 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BC3F0284FE for ; Fri, 19 May 2017 21:35:17 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B07EF28501; Fri, 19 May 2017 21:35:17 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5B710284FF for ; Fri, 19 May 2017 21:35:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756564AbdESVfN (ORCPT ); Fri, 19 May 2017 17:35:13 -0400 Received: from shelob.surriel.com ([96.67.55.147]:35583 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756364AbdESVfH (ORCPT ); Fri, 19 May 2017 17:35:07 -0400 Received: from [2603:3005:d05:2b00:224:e8ff:fe38:995c] (helo=annuminas.surriel.com) by shelob.surriel.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.63) (envelope-from ) id 1dBpQ0-00048z-Ku; Fri, 19 May 2017 17:26:40 -0400 Received: from annuminas.surriel.com (localhost.localdomain [127.0.0.1]) by annuminas.surriel.com (8.15.2/8.14.5) with ESMTP id v4JLQeGM000761; Fri, 19 May 2017 17:26:40 -0400 Received: (from riel@localhost) by annuminas.surriel.com (8.15.2/8.15.2/Submit) id v4JLQe09000760; Fri, 19 May 2017 17:26:40 -0400 X-Authentication-Warning: annuminas.surriel.com: riel set sender to riel@redhat.com using -f From: riel@redhat.com To: linux-kernel@vger.kernel.org Cc: danielmicay@gmail.com, tytso@mit.edu, keescook@chromium.org, hpa@zytor.com, luto@amacapital.net, mingo@kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, linux-sh@vger.kernel.org, ysato@users.sourceforge.jp Subject: [PATCH 3/5] x86: ascii armor the x86_64 boot init stack canary Date: Fri, 19 May 2017 17:26:34 -0400 Message-Id: <20170519212636.30440-4-riel@redhat.com> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20170519212636.30440-1-riel@redhat.com> References: <20170519212636.30440-1-riel@redhat.com> Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Rik van Riel Use the ascii-armor canary to prevent unterminated C string overflows from being able to successfully overwrite the canary, even if they somehow obtain the canary value. Inspired by execshield ascii-armor and PaX/grsecurity. Signed-off-by: Rik van Riel --- arch/x86/include/asm/stackprotector.h | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h index dcbd9bcce714..8abedf1d650e 100644 --- a/arch/x86/include/asm/stackprotector.h +++ b/arch/x86/include/asm/stackprotector.h @@ -74,6 +74,7 @@ static __always_inline void boot_init_stack_canary(void) get_random_bytes(&canary, sizeof(canary)); tsc = rdtsc(); canary += tsc + (tsc << 32UL); + canary &= CANARY_MASK; current->stack_canary = canary; #ifdef CONFIG_X86_64