From patchwork Tue Apr 23 19:49:23 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 10913683 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6B7A91390 for ; Tue, 23 Apr 2019 19:49:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5AD96285BD for ; Tue, 23 Apr 2019 19:49:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4B9092862D; Tue, 23 Apr 2019 19:49:35 +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=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,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 87CFA285BD for ; Tue, 23 Apr 2019 19:49:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726943AbfDWTtd (ORCPT ); Tue, 23 Apr 2019 15:49:33 -0400 Received: from mail-pl1-f194.google.com ([209.85.214.194]:36660 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726339AbfDWTtc (ORCPT ); Tue, 23 Apr 2019 15:49:32 -0400 Received: by mail-pl1-f194.google.com with SMTP id ck15so8039820plb.3 for ; Tue, 23 Apr 2019 12:49:31 -0700 (PDT) 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; bh=uOtKe5kyml7Js+Q+L87rwnDRHYJQCKAPp2OSkZdqNJI=; b=h3swRhiciAEavLEU7ENqTEjg0wN2iiR/MN9y8Hna8P/bGPEx/d/Eq1EQHJOlCPg+56 TnFSmyf/mnJi1j7ACoWNaui2dTB8k7lJaTGCQHpzwTgXFiHJNoczQEsDo5HtGwcx2rEG R6B7TaSFbb2Je7R7JHahwvM9UOuXUXMoeAmTI= 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; bh=uOtKe5kyml7Js+Q+L87rwnDRHYJQCKAPp2OSkZdqNJI=; b=aIQq0VETX9uDxMEd9INwhco+i7IJD4p0hRDYSqgsIu38eBj9nhsuXTmteOK4pWg9Hg 6MCMwUHCaQmtTatOeu7YghWNJ0AbaryIvHgFq/gzhLUhfVqo68FaVbZFHYD7hMaQ7Xhm C/LhVJ+p+U4Lx2DmS6zt84ZzCW0QvwdQhlC5OlBVtM0Kq7IqsWjxQphUdv9ihiqNHudw WpnKmtgJyGqwFz4lyl5lEKYy1Bz+8toisKCZDgcS046NYKxuRHNUDHIDXKw8ljEVZppZ DN4kbeahTGjDWb0FKlvUW1FjSDjKMSkZBu5QpDGe3eK2VoABnBFCw8QDemZmmiTmt9cN tzHg== X-Gm-Message-State: APjAAAWq3BAntnf3h+s/Lrt4bSJTD18vlUzWwt3qrqUrE06KsWu/siiW aSmHA9mdHumPHmCxeU4+zh2TmlTdLSQ= X-Google-Smtp-Source: APXvYqwFaRFwRy9VH6uH2q5jqI5hM3KzhHgD0CYIl1z3fLB1uzjxbvsnIzJ7vuH0E21hrNVEMnSzkQ== X-Received: by 2002:a17:902:9a85:: with SMTP id w5mr27979569plp.157.1556048971421; Tue, 23 Apr 2019 12:49:31 -0700 (PDT) Received: from www.outflux.net (173-164-112-133-Oregon.hfc.comcastbusiness.net. [173.164.112.133]) by smtp.gmail.com with ESMTPSA id a12sm17537959pgq.21.2019.04.23.12.49.29 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 23 Apr 2019 12:49:29 -0700 (PDT) From: Kees Cook To: Alexander Potapenko Cc: Kees Cook , Masahiro Yamada , James Morris , Alexander Popov , Nick Desaulniers , Kostya Serebryany , Dmitry Vyukov , Sandeep Patil , Laura Abbott , Randy Dunlap , Michal Marek , Emese Revfy , "Serge E. Hallyn" , Kernel Hardening , linux-security-module , Linux Kbuild mailing list , Linux Kernel Mailing List Subject: [PATCH v3 1/3] security: Create "kernel hardening" config area Date: Tue, 23 Apr 2019 12:49:23 -0700 Message-Id: <20190423194925.32151-2-keescook@chromium.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190423194925.32151-1-keescook@chromium.org> References: <20190423194925.32151-1-keescook@chromium.org> Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Right now kernel hardening options are scattered around various Kconfig files. This can be a central place to collect these kinds of options going forward. This is initially populated with the memory initialization options from the gcc-plugins. Signed-off-by: Kees Cook --- scripts/gcc-plugins/Kconfig | 75 +++--------------------------- security/Kconfig | 2 + security/Kconfig.hardening | 93 +++++++++++++++++++++++++++++++++++++ 3 files changed, 101 insertions(+), 69 deletions(-) create mode 100644 security/Kconfig.hardening diff --git a/scripts/gcc-plugins/Kconfig b/scripts/gcc-plugins/Kconfig index 74271dba4f94..352f03878a1e 100644 --- a/scripts/gcc-plugins/Kconfig +++ b/scripts/gcc-plugins/Kconfig @@ -13,17 +13,19 @@ config HAVE_GCC_PLUGINS An arch should select this symbol if it supports building with GCC plugins. -menuconfig GCC_PLUGINS - bool "GCC plugins" +config GCC_PLUGINS + bool depends on HAVE_GCC_PLUGINS depends on PLUGIN_HOSTCC != "" + default y help GCC plugins are loadable modules that provide extra features to the compiler. They are useful for runtime instrumentation and static analysis. See Documentation/gcc-plugins.txt for details. -if GCC_PLUGINS +menu "GCC plugins" + depends on GCC_PLUGINS config GCC_PLUGIN_CYC_COMPLEXITY bool "Compute the cyclomatic complexity of a function" if EXPERT @@ -66,71 +68,6 @@ config GCC_PLUGIN_LATENT_ENTROPY * https://grsecurity.net/ * https://pax.grsecurity.net/ -config GCC_PLUGIN_STRUCTLEAK - bool "Zero initialize stack variables" - help - While the kernel is built with warnings enabled for any missed - stack variable initializations, this warning is silenced for - anything passed by reference to another function, under the - occasionally misguided assumption that the function will do - the initialization. As this regularly leads to exploitable - flaws, this plugin is available to identify and zero-initialize - such variables, depending on the chosen level of coverage. - - This plugin was originally ported from grsecurity/PaX. More - information at: - * https://grsecurity.net/ - * https://pax.grsecurity.net/ - -choice - prompt "Coverage" - depends on GCC_PLUGIN_STRUCTLEAK - default GCC_PLUGIN_STRUCTLEAK_BYREF_ALL - help - This chooses the level of coverage over classes of potentially - uninitialized variables. The selected class will be - zero-initialized before use. - - config GCC_PLUGIN_STRUCTLEAK_USER - bool "structs marked for userspace" - help - Zero-initialize any structures on the stack containing - a __user attribute. This can prevent some classes of - uninitialized stack variable exploits and information - exposures, like CVE-2013-2141: - https://git.kernel.org/linus/b9e146d8eb3b9eca - - config GCC_PLUGIN_STRUCTLEAK_BYREF - bool "structs passed by reference" - help - Zero-initialize any structures on the stack that may - be passed by reference and had not already been - explicitly initialized. This can prevent most classes - of uninitialized stack variable exploits and information - exposures, like CVE-2017-1000410: - https://git.kernel.org/linus/06e7e776ca4d3654 - - config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL - bool "anything passed by reference" - help - Zero-initialize any stack variables that may be passed - by reference and had not already been explicitly - initialized. This is intended to eliminate all classes - of uninitialized stack variable exploits and information - exposures. - -endchoice - -config GCC_PLUGIN_STRUCTLEAK_VERBOSE - bool "Report forcefully initialized variables" - depends on GCC_PLUGIN_STRUCTLEAK - depends on !COMPILE_TEST # too noisy - help - This option will cause a warning to be printed each time the - structleak plugin finds a variable it thinks needs to be - initialized. Since not all existing initializers are detected - by the plugin, this can produce false positive warnings. - config GCC_PLUGIN_RANDSTRUCT bool "Randomize layout of sensitive kernel structures" select MODVERSIONS if MODULES @@ -226,4 +163,4 @@ config GCC_PLUGIN_ARM_SSP_PER_TASK bool depends on GCC_PLUGINS && ARM -endif +endmenu diff --git a/security/Kconfig b/security/Kconfig index 1d6463fb1450..7aec8d094ce2 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -249,5 +249,7 @@ config LSM If unsure, leave this as the default. +source "security/Kconfig.hardening" + endmenu diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening new file mode 100644 index 000000000000..19881341f1c2 --- /dev/null +++ b/security/Kconfig.hardening @@ -0,0 +1,93 @@ +menu "Kernel hardening options" + +config GCC_PLUGIN_STRUCTLEAK + bool + help + While the kernel is built with warnings enabled for any missed + stack variable initializations, this warning is silenced for + anything passed by reference to another function, under the + occasionally misguided assumption that the function will do + the initialization. As this regularly leads to exploitable + flaws, this plugin is available to identify and zero-initialize + such variables, depending on the chosen level of coverage. + + This plugin was originally ported from grsecurity/PaX. More + information at: + * https://grsecurity.net/ + * https://pax.grsecurity.net/ + +menu "Memory initialization" + +choice + prompt "Initialize kernel stack variables at function entry" + default GCC_PLUGIN_STRUCTLEAK_BYREF_ALL if COMPILE_TEST && GCC_PLUGINS + default INIT_STACK_NONE + help + This option enables initialization of stack variables at + function entry time. This has the possibility to have the + greatest coverage (since all functions can have their + variables initialized), but the performance impact depends + on the function calling complexity of a given workload's + syscalls. + + This chooses the level of coverage over classes of potentially + uninitialized variables. The selected class will be + initialized before use in a function. + + config INIT_STACK_NONE + bool "no automatic initialization (weakest)" + help + Disable automatic stack variable initialization. + This leaves the kernel vulnerable to the standard + classes of uninitialized stack variable exploits + and information exposures. + + config GCC_PLUGIN_STRUCTLEAK_USER + bool "zero-init structs marked for userspace (weak)" + depends on GCC_PLUGINS + select GCC_PLUGIN_STRUCTLEAK + help + Zero-initialize any structures on the stack containing + a __user attribute. This can prevent some classes of + uninitialized stack variable exploits and information + exposures, like CVE-2013-2141: + https://git.kernel.org/linus/b9e146d8eb3b9eca + + config GCC_PLUGIN_STRUCTLEAK_BYREF + bool "zero-init structs passed by reference (strong)" + depends on GCC_PLUGINS + select GCC_PLUGIN_STRUCTLEAK + help + Zero-initialize any structures on the stack that may + be passed by reference and had not already been + explicitly initialized. This can prevent most classes + of uninitialized stack variable exploits and information + exposures, like CVE-2017-1000410: + https://git.kernel.org/linus/06e7e776ca4d3654 + + config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL + bool "zero-init anything passed by reference (very strong)" + depends on GCC_PLUGINS + select GCC_PLUGIN_STRUCTLEAK + help + Zero-initialize any stack variables that may be passed + by reference and had not already been explicitly + initialized. This is intended to eliminate all classes + of uninitialized stack variable exploits and information + exposures. + +endchoice + +config GCC_PLUGIN_STRUCTLEAK_VERBOSE + bool "Report forcefully initialized variables" + depends on GCC_PLUGIN_STRUCTLEAK + depends on !COMPILE_TEST # too noisy + help + This option will cause a warning to be printed each time the + structleak plugin finds a variable it thinks needs to be + initialized. Since not all existing initializers are detected + by the plugin, this can produce false positive warnings. + +endmenu + +endmenu