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=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 96157C3815B for ; Mon, 20 Apr 2020 20:03:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 78CD520736 for ; Mon, 20 Apr 2020 20:03:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726709AbgDTUDI convert rfc822-to-8bit (ORCPT ); Mon, 20 Apr 2020 16:03:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725918AbgDTUDI (ORCPT ); Mon, 20 Apr 2020 16:03:08 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E1E36C061A0C; Mon, 20 Apr 2020 13:03:07 -0700 (PDT) Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jQcdD-0005ze-Rg; Mon, 20 Apr 2020 22:03:03 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 76FC81C007F; Mon, 20 Apr 2020 22:03:03 +0200 (CEST) Date: Mon, 20 Apr 2020 20:03:03 -0000 From: "tip-bot2 for Kees Cook" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: core/core] arm32/64/elf: Add tables to document READ_IMPLIES_EXEC Cc: Kees Cook , Borislav Petkov , Jason Gunthorpe , Catalin Marinas , x86 , LKML In-Reply-To: <20200327064820.12602-5-keescook@chromium.org> References: <20200327064820.12602-5-keescook@chromium.org> MIME-Version: 1.0 Message-ID: <158741298311.28353.9327807633618864541.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8BIT X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the core/core branch of tip: Commit-ID: 78066055b08096ed3282c027de9d9e137f9a1580 Gitweb: https://git.kernel.org/tip/78066055b08096ed3282c027de9d9e137f9a1580 Author: Kees Cook AuthorDate: Thu, 26 Mar 2020 23:48:18 -07:00 Committer: Borislav Petkov CommitterDate: Mon, 20 Apr 2020 19:41:50 +02:00 arm32/64/elf: Add tables to document READ_IMPLIES_EXEC Add tables to document the current behavior of READ_IMPLIES_EXEC in preparation for changing the behavior for both arm64 and arm. Signed-off-by: Kees Cook Signed-off-by: Borislav Petkov Reviewed-by: Jason Gunthorpe Reviewed-by: Catalin Marinas Link: https://lkml.kernel.org/r/20200327064820.12602-5-keescook@chromium.org --- arch/arm/kernel/elf.c | 24 +++++++++++++++++++++--- arch/arm64/include/asm/elf.h | 20 ++++++++++++++++++++ 2 files changed, 41 insertions(+), 3 deletions(-) diff --git a/arch/arm/kernel/elf.c b/arch/arm/kernel/elf.c index 1824229..5ccd4ac 100644 --- a/arch/arm/kernel/elf.c +++ b/arch/arm/kernel/elf.c @@ -78,9 +78,27 @@ void elf_set_personality(const struct elf32_hdr *x) EXPORT_SYMBOL(elf_set_personality); /* - * Set READ_IMPLIES_EXEC if: - * - the binary requires an executable stack - * - we're running on a CPU which doesn't support NX. + * An executable for which elf_read_implies_exec() returns TRUE will + * have the READ_IMPLIES_EXEC personality flag set automatically. + * + * The decision process for determining the results are: + * + *              CPU: | lacks NX*  | has NX | + * ELF:              |            |           | + * ---------------------|------------|------------| + * missing PT_GNU_STACK | exec-all   | exec-all  | + * PT_GNU_STACK == RWX  | exec-all   | exec-all  | + * PT_GNU_STACK == RW   | exec-all  | exec-none | + * + * exec-all : all PROT_READ user mappings are executable, except when + * backed by files on a noexec-filesystem. + * exec-none : only PROT_EXEC user mappings are executable. + * + * *this column has no architectural effect: NX markings are ignored by + * hardware, but may have behavioral effects when "wants X" collides with + * "cannot be X" constraints in memory permission flags, as in + * https://lkml.kernel.org/r/20190418055759.GA3155@mellanox.com + * */ int arm_elf_read_implies_exec(int executable_stack) { diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h index b618017..986ecf4 100644 --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -96,6 +96,26 @@ */ #define elf_check_arch(x) ((x)->e_machine == EM_AARCH64) +/* + * An executable for which elf_read_implies_exec() returns TRUE will + * have the READ_IMPLIES_EXEC personality flag set automatically. + * + * The decision process for determining the results are: + * + *              CPU*: | arm32    | arm64 | + * ELF:              |            |            | + * ---------------------|------------|------------| + * missing PT_GNU_STACK | exec-all   | exec-all   | + * PT_GNU_STACK == RWX  | exec-all   | exec-all   | + * PT_GNU_STACK == RW   | exec-none | exec-none | + * + * exec-all : all PROT_READ user mappings are executable, except when + * backed by files on a noexec-filesystem. + * exec-none : only PROT_EXEC user mappings are executable. + * + * *all arm64 CPUs support NX, so there is no "lacks NX" column. + * + */ #define elf_read_implies_exec(ex,stk) (stk != EXSTACK_DISABLE_X) #define CORE_DUMP_USE_REGSET