From patchwork Mon Feb 10 19:30:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 11374015 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 B5D19109A for ; Mon, 10 Feb 2020 19:31:45 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8D72E20838 for ; Mon, 10 Feb 2020 19:31:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="c7FacXxQ"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="L4WYG666" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8D72E20838 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=jUdQS07ZstOejTP69ESqgOSF40mhIvVYokPrNdc/B3M=; b=c7FacXxQKhXJ8y lV0sq5TCAZ2edPljKdwW4T2Q+6Zphjf9k2HfZu8ll6mqmC7k7YSgTyZfUHzCPU559ygGVJyr8zLE4 9LAfn2vPILX+quiVs5fi6eLwaP+wLWdVTWm1VUaLgXbwppSLWHGWH2drfl3ZmwRcptA7TcJ3x+tcg SRtQotao54iX3RDcfByCSabv9GErjHG7zpJRWh0E23mFzutjfjqWRkKKSyu+XuhCuTQTxiMsL3K5+ SK/zMN+TbsOTlkCyDNEYclnqZT3jZf/FT7CuzqVHIEMD5EJCglCF0P6OZeu9iN3kXARVumTGJ4FYH zpgHC3Wc5OKg2rKjJJsQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j1EmV-0006B5-Sx; Mon, 10 Feb 2020 19:31:43 +0000 Received: from mail-ot1-x341.google.com ([2607:f8b0:4864:20::341]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1j1Elp-0005SY-Hy for linux-arm-kernel@lists.infradead.org; Mon, 10 Feb 2020 19:31:03 +0000 Received: by mail-ot1-x341.google.com with SMTP id a15so7598336otf.1 for ; Mon, 10 Feb 2020 11:31:01 -0800 (PST) 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=Xgo1yExYE1FoOrHi/q0yB3FWShMft6x5k4WGrQxm170=; b=L4WYG666B6q1Et3bcdlnVISVkOrsiaz/021i2HOtSDO+5jbbvUU8qOhFuAJpImd9Of tHvcCRS71nZ2E2PCYI1v1I7/5Fx8qC14IBkh3bZudUkhVCFVSTRXv68LgS4rolJ8b7NO oy2IjZYniOec+89rewQ3DeqzhHAbfLUi9rvdA= 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=Xgo1yExYE1FoOrHi/q0yB3FWShMft6x5k4WGrQxm170=; b=V7g/F8JV0gdlXbq81iXU16quVSMMJkQ6DAFVVsvqyUpOxN1xDa8tJSd9oPECJxKeiI M1APrQG3xl5tvBIWIFbVZ+DgWrO6bzcE6BTxwD4GSWqLf33gzoAmcw4KSHG1PLcaR6EW 2DvEBTGdj4xJPA8VSIsu9QxL60XM3W6ChQ2YveLgBhxbUpSJnvDiY3u/rw3LI9eAkeJg Z5mqJcBKbPSC6pWu4S13EYFg4VFYtwUgzKzffa855Yl0vRV7rgzNLTmNWWhORQH2vNkR 2xNgnGFQreoA7eN9YhdhWDFbcy1KhnlxikwL62nwzbCgDq9b4hf0y7AE7+gleWy4JuJj CwJQ== X-Gm-Message-State: APjAAAXVo17tQpoZ3Sv8PHI4C89Ums46AQEMi0Eaxn7kb0mI7XSc7PPY hkGEEyuVFiEB1iXHi4hUhMfBEw== X-Google-Smtp-Source: APXvYqxrCRbeRObAKsREPcdxJmg1NESdR+jwjL0VLXI5HeLb3NvoJQshGJ4OJNNqOglQAXv1YayQEA== X-Received: by 2002:a9d:6e8f:: with SMTP id a15mr2204441otr.178.1581363060517; Mon, 10 Feb 2020 11:31:00 -0800 (PST) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id b145sm356027oii.31.2020.02.10.11.30.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Feb 2020 11:30:58 -0800 (PST) From: Kees Cook To: Ingo Molnar Subject: [PATCH v3 4/7] arm32/64, elf: Add tables to document READ_IMPLIES_EXEC Date: Mon, 10 Feb 2020 11:30:46 -0800 Message-Id: <20200210193049.64362-5-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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200210_113101_588821_8D31C469 X-CRM114-Status: GOOD ( 13.11 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.3 on bombadil.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:341 listed in] [list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.0 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender 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: Kees Cook , Jann Horn , Catalin Marinas , x86@kernel.org, Hector Marco-Gisbert , Russell King , Will Deacon , linux-kernel@vger.kernel.org, Jason Gunthorpe , linux-kselftest@vger.kernel.org, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org 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 Reviewed-by: Catalin Marinas --- 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 182422981386..2f69cf978fe3 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 GNU_STACK | exec-all   | exec-all  | + * GNU_STACK == RWX  | exec-all   | exec-all  | + * 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 b618017205a3..7fc779e3f1ec 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 GNU_STACK | exec-all   | exec-all   | + * GNU_STACK == RWX  | exec-all   | exec-all   | + * 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