From patchwork Mon Feb 10 19:30:45 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 11374013 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D1685109A for ; Mon, 10 Feb 2020 19:31:39 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 36E5220873 for ; Mon, 10 Feb 2020 19:31:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="mqEHj3cJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 36E5220873 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17764-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 12088 invoked by uid 550); 10 Feb 2020 19:31:14 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 11983 invoked from network); 10 Feb 2020 19:31:13 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=Hedv3uQpLYtG/8d40iSwsTwWwbRFJKr8vrN4ZiDg04Q=; b=mqEHj3cJctfFXlmy16cRdbd3ZRwBg+PBoqBPYVmqQH/qHbN5NUcjIYDQxGJmRKQ7wa Gh/oTcwv3s+WJTQGeN5oXvRGmYE52sD2Oy62uw9zNjtHK9oLi+CKMUz2V13jB1bNCceN HKebkK1prPWHrTSh29Rcs3l4gWJQcq2tOzhxQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Hedv3uQpLYtG/8d40iSwsTwWwbRFJKr8vrN4ZiDg04Q=; b=NuBv9/hkGLTThOtpp2KdeY1Moh/4UrQL++mhW1QepEIKN7q00aVW+0NkCUWLRIRzEw a++Kp2MCFUtjmQjm3ZN8yzu7ehnz8V0qTgWB194nB5R/5Fg23pOSiLXRNcJSZWhstOI9 KUAZonIzNxQqMnK2PAJv6gk5ufp561WIHjP14a89eD88eOC9Gbd+LCLny5Nk5/wRLarw 12dG2vprX5U8vs++FrG+dyBfS7wax6EIDX29WpiV76AKvQsLvbOMH6PjIgnM9kiH3iW6 +ikDZlP5F/v5B6WR7a4wotWsvxiq8cBAqqwMsWo02BykMUhQ9ZDWNAhsapq2cxNAtUJD Oe5w== X-Gm-Message-State: APjAAAVmUh9O3kJ+HFHjsfUhnnZ4bV422LD/SNGfYuwK09+3Xl0goj4A 7L4GZNcxwR2P/0DcuS2N7hPrgQ== X-Google-Smtp-Source: APXvYqxzrrMjKkyUG9U1mzxeIF/mXf4CdliJjd23xPg8Q25YEpKS/E/iAhQV5XTWVKedZ6gqCTRpxg== X-Received: by 2002:aca:be57:: with SMTP id o84mr419172oif.138.1581363061318; Mon, 10 Feb 2020 11:31:01 -0800 (PST) From: Kees Cook To: Ingo Molnar Cc: Kees Cook , Hector Marco-Gisbert , Catalin Marinas , Will Deacon , Jason Gunthorpe , Jann Horn , Russell King , x86@kernel.org, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v3 3/7] x86/elf: Disable automatic READ_IMPLIES_EXEC for 64-bit address spaces Date: Mon, 10 Feb 2020 11:30:45 -0800 Message-Id: <20200210193049.64362-4-keescook@chromium.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200210193049.64362-1-keescook@chromium.org> References: <20200210193049.64362-1-keescook@chromium.org> MIME-Version: 1.0 With modern x86 64-bit environments, there should never be a need for automatic READ_IMPLIES_EXEC, as the architecture is intended to always be execute-bit aware (as in, the default memory protection should be NX unless a region explicitly requests to be executable). There were very old x86_64 systems that lacked the NX bit, but for those, the NX bit is, obviously, unenforceable, so these changes should have no impact on them. Suggested-by: Hector Marco-Gisbert Signed-off-by: Kees Cook --- arch/x86/include/asm/elf.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h index a7035065377c..c9b7be0bcad3 100644 --- a/arch/x86/include/asm/elf.h +++ b/arch/x86/include/asm/elf.h @@ -287,7 +287,7 @@ extern u32 elf_hwcap2; *              CPU: | lacks NX*  | has NX, ia32     | has NX, x86_64 | * ELF:              |            |                  |                | * -------------------------------|------------------|----------------| - * missing GNU_STACK | exec-all   | exec-all         | exec-all       | + * missing GNU_STACK | exec-all   | exec-all         | exec-none      | * GNU_STACK == RWX  | exec-stack | exec-stack       | exec-stack     | * GNU_STACK == RW   | exec-none  | exec-none        | exec-none      | * @@ -303,7 +303,7 @@ extern u32 elf_hwcap2; * */ #define elf_read_implies_exec(ex, executable_stack) \ - (executable_stack == EXSTACK_DEFAULT) + (mmap_is_ia32() && executable_stack == EXSTACK_DEFAULT) struct task_struct;