From patchwork Wed Aug 17 00:20:28 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 9285017 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id D916060574 for ; Wed, 17 Aug 2016 00:21:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C975D287A6 for ; Wed, 17 Aug 2016 00:21:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BDE57288A1; Wed, 17 Aug 2016 00:21:09 +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=-4.1 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,T_DKIM_INVALID 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 A469E287A6 for ; Wed, 17 Aug 2016 00:21:08 +0000 (UTC) Received: (qmail 31889 invoked by uid 550); 17 Aug 2016 00:20:48 -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: Reply-To: kernel-hardening@lists.openwall.com Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 31759 invoked from network); 17 Aug 2016 00:20:45 -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=p2SNJvI/EH9nFYdAlT2tGPwu5QceSvx9hgLlWGsXK/M=; b=Wpe1G3cPDBn2jzLorc31RshYSd5ZQyJpy300lvRkC32f0ijMDsK1hTW35dNUui+1CG mbxSDkVYMTOVGctktT3sN7wmDo6ZikJaeFZGM6HPcHpXAtS6Z6qwPofzFqBKRtCRcv/T T/phDvI0tXFMZkyO1eRSLg63zEZfZdtQa8cOQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=p2SNJvI/EH9nFYdAlT2tGPwu5QceSvx9hgLlWGsXK/M=; b=h60gl0ZO9CEQvD9v57/l4cGXaBM/Vt7VIPgNhLgWfGnpq0V6JueLk98jkJ6jCV7LAG c5KCkboG7kbGAemePHd4QHQBbd1/k2OszHvQMRqfYX/yiuLkOXsvhinIcGuBuhr/jGbl 9vj6sqXvn6DafVhiSuu/1d5bzicZX645CBPqrUFDdXzBOYbxf7WglDS3LMWPwId51oO5 urXBYmU6m2QxS2JlPOqUq1wI7IEJvCJ/HbuNl+GzTT64qAk/o3GBNkrudqJIwHjg2WyU Qv9hP2bW/tG2Br/uMmrG28Sjtetigt9fyMYUJ4t/xRmtryNomEflFdCvC5tQ8k4WeWZi AElw== X-Gm-Message-State: AEkooutjbYWh1QcQr1JwMfPVsdyI1GfLkhe9unBA8gqcSAwPDdbGWT/Sz3lnneojOlApbgTO X-Received: by 10.98.216.199 with SMTP id e190mr69051983pfg.123.1471393233618; Tue, 16 Aug 2016 17:20:33 -0700 (PDT) From: Kees Cook To: "Paul E . McKenney" Cc: Kees Cook , Laura Abbott , Steven Rostedt , Stephen Boyd , Daniel Micay , Joe Perches , Arnd Bergmann , Greg Kroah-Hartman , Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , "Aneesh Kumar K.V" , "Kirill A. Shutemov" , Michael Ellerman , Dan Williams , Andrew Morton , Ingo Molnar , Thomas Gleixner , Josef Bacik , Andrey Ryabinin , Tejun Heo , Nikolay Aleksandrov , Dmitry Vyukov , linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Date: Tue, 16 Aug 2016 17:20:28 -0700 Message-Id: <1471393229-27182-5-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1471393229-27182-1-git-send-email-keescook@chromium.org> References: <1471393229-27182-1-git-send-email-keescook@chromium.org> Subject: [kernel-hardening] [PATCH v2 4/5] bug: Provide toggle for BUG on data corruption X-Virus-Scanned: ClamAV using ClamSMTP The kernel checks for cases of data structure corruption under some CONFIGs (e.g. CONFIG_DEBUG_LIST). When corruption is detected, some systems may want to BUG() immediately instead of letting the system run with known corruption. Usually these kinds of manipulation primitives can be used by security flaws to gain arbitrary memory write control. This provides a new config CONFIG_BUG_ON_DATA_CORRUPTION and a corresponding macro CHECK_DATA_CORRUPTION for handling these situations. Notably, even if not BUGing, the kernel should not continue processing the corrupted structure. This is inspired by similar hardening by Stephen Boyd in MSM kernels, and in PaX and Grsecurity, which is likely in response to earlier removal of the BUG calls in commit 924d9addb9b1 ("list debugging: use WARN() instead of BUG()"). Signed-off-by: Kees Cook --- include/linux/bug.h | 17 ++++++++++++++++ lib/Kconfig.debug | 10 ++++++++++ lib/list_debug.c | 57 +++++++++++++++++++++-------------------------------- 3 files changed, 49 insertions(+), 35 deletions(-) diff --git a/include/linux/bug.h b/include/linux/bug.h index e51b0709e78d..011e8e95aa0e 100644 --- a/include/linux/bug.h +++ b/include/linux/bug.h @@ -118,4 +118,21 @@ static inline enum bug_trap_type report_bug(unsigned long bug_addr, } #endif /* CONFIG_GENERIC_BUG */ + +/* + * Since detected data corruption should stop operation on the affected + * structures, this returns false if the corruption condition is found. + */ +#define CHECK_DATA_CORRUPTION(condition, format...) \ + do { \ + if (unlikely(condition)) { \ + if (IS_ENABLED(CONFIG_BUG_ON_DATA_CORRUPTION)) { \ + printk(KERN_ERR format); \ + BUG(); \ + } else \ + WARN(1, format); \ + return false; \ + } \ + } while (0) + #endif /* _LINUX_BUG_H */ diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 2307d7c89dac..58d358a4c7f3 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1987,6 +1987,16 @@ config TEST_STATIC_KEYS If unsure, say N. +config BUG_ON_DATA_CORRUPTION + bool "Trigger a BUG when data corruption is detected" + select CONFIG_DEBUG_LIST + help + Select this option if the kernel should BUG when it encounters + data corruption in kernel memory structures when they get checked + for validity. + + If unsure, say N. + source "samples/Kconfig" source "lib/Kconfig.kgdb" diff --git a/lib/list_debug.c b/lib/list_debug.c index 276565fca2a6..7f7bfa55eb6d 100644 --- a/lib/list_debug.c +++ b/lib/list_debug.c @@ -20,21 +20,16 @@ bool __list_add_valid(struct list_head *new, struct list_head *prev, struct list_head *next) { - if (unlikely(next->prev != prev)) { - WARN(1, "list_add corruption. next->prev should be prev (%p), but was %p. (next=%p).\n", - prev, next->prev, next); - return false; - } - if (unlikely(prev->next != next)) { - WARN(1, "list_add corruption. prev->next should be next (%p), but was %p. (prev=%p).\n", - next, prev->next, prev); - return false; - } - if (unlikely(new == prev || new == next)) { - WARN(1, "list_add double add: new=%p, prev=%p, next=%p.\n", - new, prev, next); - return false; - } + CHECK_DATA_CORRUPTION(next->prev != prev, + "list_add corruption. next->prev should be prev (%p), but was %p. (next=%p).\n", + prev, next->prev, next); + CHECK_DATA_CORRUPTION(prev->next != next, + "list_add corruption. prev->next should be next (%p), but was %p. (prev=%p).\n", + next, prev->next, prev); + CHECK_DATA_CORRUPTION(new == prev || new == next, + "list_add double add: new=%p, prev=%p, next=%p.\n", + new, prev, next); + return true; } EXPORT_SYMBOL(__list_add_valid); @@ -46,26 +41,18 @@ bool __list_del_entry_valid(struct list_head *entry) prev = entry->prev; next = entry->next; - if (unlikely(next == LIST_POISON1)) { - WARN(1, "list_del corruption, %p->next is LIST_POISON1 (%p)\n", - entry, LIST_POISON1); - return false; - } - if (unlikely(prev == LIST_POISON2)) { - WARN(1, "list_del corruption, %p->prev is LIST_POISON2 (%p)\n", - entry, LIST_POISON2); - return false; - } - if (unlikely(prev->next != entry)) { - WARN(1, "list_del corruption. prev->next should be %p, but was %p\n", - entry, prev->next); - return false; - } - if (unlikely(next->prev != entry)) { - WARN(1, "list_del corruption. next->prev should be %p, but was %p\n", - entry, next->prev); - return false; - } + CHECK_DATA_CORRUPTION(next == LIST_POISON1, + "list_del corruption, %p->next is LIST_POISON1 (%p)\n", + entry, LIST_POISON1); + CHECK_DATA_CORRUPTION(prev == LIST_POISON2, + "list_del corruption, %p->prev is LIST_POISON2 (%p)\n", + entry, LIST_POISON2); + CHECK_DATA_CORRUPTION(prev->next != entry, + "list_del corruption. prev->next should be %p, but was %p\n", + entry, prev->next); + CHECK_DATA_CORRUPTION(next->prev != entry, + "list_del corruption. next->prev should be %p, but was %p\n", + entry, next->prev); return true; }