From patchwork Wed Apr 10 16:16:10 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 10894335 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 0C65D139A for ; Wed, 10 Apr 2019 16:16:59 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F0DE128B94 for ; Wed, 10 Apr 2019 16:16:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EF17128CE9; Wed, 10 Apr 2019 16:16:58 +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=-5.3 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 9EA6128D00 for ; Wed, 10 Apr 2019 16:16:57 +0000 (UTC) Received: (qmail 16273 invoked by uid 550); 10 Apr 2019 16:16:35 -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 16168 invoked from network); 10 Apr 2019 16:16:33 -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; bh=4Wn4tYZKtyQIbqgdelcndTQ7HKhw2rd1tFQ7AR2NLSY=; b=XLsREfCwxZo6YbXBti+6yI1YNNTD5ljjsLcsyNo/Y7t3unozeSVUQw1UBBrgBvftpk b5SxINtyvYKXwhcWCPXNESzyhk2C/F6sYiSseOZf7O2z60mAZMDfqIEnqlX2B5WHZ9xi pGk+EbfYaPiilcHxNgTFhT2yOyCCqV7UCrJbQ= 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=4Wn4tYZKtyQIbqgdelcndTQ7HKhw2rd1tFQ7AR2NLSY=; b=GISOY6y8xRjyp2kuHues6ZPtwTuR1oKCUgDGU0CnBHf/6THUlEEp2Avh0E2UUdzO7Y DA6hJyAplO0g62/Yf7IG6hq8A+Br+hOmSjhwbsRMzO+6igELX/kt+R9nBy2jp/0eYMbp ZeAWTgBoL29ThWCw5eiPdeKt1ISTVD4JkdRZhr6LzZJwIQx9SaTTLlI0L/N3KN8ss+2J KkDxLeLigOhfa3JFG/K6T8IZnpt4kqsKfcYuP4GbjLnPDS5c+P7Vs4pFlYSWY2l9u5CQ rTH69k3iu5SZlYuGajIjyqwjWqjmFi59KQLBI8I7k8FZ6rV1dJshjhYKtm0U5Hmirlgx yB6Q== X-Gm-Message-State: APjAAAXbi12eaadunw5aE9pe+FeC+Yw4doSDtvJxktfzn8tRMe5kr6zZ J+04LaMrq8XMO23ESYaFJe5psA== X-Google-Smtp-Source: APXvYqxK+h5jiN9iKivMZH6Qpj7WRrDDWue1wq5Qvc4y2pUUe1u7rjZAoe9SvEw052fJmBYZQ8cDDw== X-Received: by 2002:a17:902:b191:: with SMTP id s17mr43294465plr.70.1554912981415; Wed, 10 Apr 2019 09:16:21 -0700 (PDT) From: Kees Cook To: Masahiro Yamada Cc: Kees Cook , Alexander Potapenko , Nick Desaulniers , Kostya Serebryany , Dmitry Vyukov , Sandeep Patil , Laura Abbott , Randy Dunlap , Alexander Popov , Michal Marek , Emese Revfy , James Morris , "Serge E. Hallyn" , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: [PATCH 1/3] Kconfig: Create "kernel hardening" config area Date: Wed, 10 Apr 2019 09:16:10 -0700 Message-Id: <20190410161612.18545-2-keescook@chromium.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190410161612.18545-1-keescook@chromium.org> References: <20190410161612.18545-1-keescook@chromium.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. Signed-off-by: Kees Cook --- scripts/gcc-plugins/Kconfig | 70 ++------------------------- security/Kconfig | 2 + security/Kconfig.hardening | 94 +++++++++++++++++++++++++++++++++++++ 3 files changed, 99 insertions(+), 67 deletions(-) create mode 100644 security/Kconfig.hardening diff --git a/scripts/gcc-plugins/Kconfig b/scripts/gcc-plugins/Kconfig index 74271dba4f94..01874ef0f883 100644 --- a/scripts/gcc-plugins/Kconfig +++ b/scripts/gcc-plugins/Kconfig @@ -13,10 +13,11 @@ 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. @@ -66,71 +67,6 @@ 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 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..8223a8ab1a12 --- /dev/null +++ b/security/Kconfig.hardening @@ -0,0 +1,94 @@ +menu "Kernel hardening options" + +config GCC_PLUGIN_STRUCTLEAK + bool + depends on GCC_PLUGIN_STRUCTLEAK_USER || GCC_PLUGIN_STRUCTLEAK_BYREF || GCC_PLUGIN_STRUCTLEAK_BYREF_ALL + 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" + depends on CC_HAS_AUTO_VAR_INIT || 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