From patchwork Wed Jul 20 20:26:57 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 9240531 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 1B4026077C for ; Wed, 20 Jul 2016 20:33:55 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0C58A27C26 for ; Wed, 20 Jul 2016 20:33:55 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 006DD27D4D; Wed, 20 Jul 2016 20:33:54 +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=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 84E7C27C26 for ; Wed, 20 Jul 2016 20:33:54 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1bPyAJ-0004fo-1e; Wed, 20 Jul 2016 20:32:23 +0000 Received: from mail-pf0-x232.google.com ([2607:f8b0:400e:c00::232]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1bPy5k-0007kj-KK for linux-arm-kernel@lists.infradead.org; Wed, 20 Jul 2016 20:27:43 +0000 Received: by mail-pf0-x232.google.com with SMTP id y134so22374105pfg.0 for ; Wed, 20 Jul 2016 13:27:20 -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=m6ZMyPSI+wnfFONnWfXh8nbvuRtK/xUyUwlZueocUkg=; b=NpLZi0b4wZzpcFU/xreJ+LN9gXUKeA6jBFP7lWPUpo6axc6t5yfPdQ4iQBdqmiCsQk +uVtagL3y/hOtl4KnX60PlAsrdpavX7UksTm8o3XYo6qpN3Ro6o312v1ie24NWGeyNS/ 6BaPTOSAjhWv2rAtGyGNjpz4xl+OEmoo0VaWg= 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=m6ZMyPSI+wnfFONnWfXh8nbvuRtK/xUyUwlZueocUkg=; b=WLz6FRDIoeoU7XiZ4HCuaP0IIOv6RuQ80xDWytSdKsnuR1+HQbV9xAHVZWs8GR/Sl7 0eqhuvljwxZM2Z//nYn5JQN5b7AJakv3ME1CvgHJBCTjJyhGWBTW7e2iML9dFkCt4tny f357bjkt55CNcnw7csZV2iOhX1Gcz4emj6tEGyAA1EvHuXcNTc5BsmmI93sfDAT4Fdjh 7lNY1jeK6tDSZhBen4uSg4VSV6QOengAWfhxiRMAF2q9wNS010bW8I34MxbZl9pYw0jU TH5qulyMsRIbG0Px5uUXe/BNPrw2ubyR+0ADsfiZ2E3dL3Nxqxu3izcX2cPOJwcfQTV+ KOfw== X-Gm-Message-State: ALyK8tIU43X2Dou5kIXGIFlxYTl+kFeICLpdGffWLvKm0Lj5rt6EGXzO3O7N2oG2Hbo0TCAg X-Received: by 10.98.192.144 with SMTP id g16mr68250989pfk.55.1469046439954; Wed, 20 Jul 2016 13:27:19 -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 k78sm6585536pfa.78.2016.07.20.13.27.17 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 20 Jul 2016 13:27:18 -0700 (PDT) From: Kees Cook To: kernel-hardening@lists.openwall.com Subject: [PATCH v4 02/12] mm: Implement stack frame object validation Date: Wed, 20 Jul 2016 13:26:57 -0700 Message-Id: <1469046427-12696-3-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1469046427-12696-1-git-send-email-keescook@chromium.org> References: <1469046427-12696-1-git-send-email-keescook@chromium.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160720_132740_816411_909E1A5B X-CRM114-Status: GOOD ( 18.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jan Kara , Benjamin Herrenschmidt , Balbir Singh , Will Deacon , linux-mm@kvack.org, sparclinux@vger.kernel.org, linux-ia64@vger.kernel.org, Christoph Lameter , Andrea Arcangeli , linux-arch@vger.kernel.org, Michael Ellerman , x86@kernel.org, Russell King , linux-arm-kernel@lists.infradead.org, Catalin Marinas , PaX Team , Borislav Petkov , Mathias Krause , Fenghua Yu , Rik van Riel , Kees Cook , Vitaly Wool , David Rientjes , Tony Luck , Andy Lutomirski , Josh Poimboeuf , Andrew Morton , Dmitry Vyukov , Laura Abbott , Brad Spengler , Ard Biesheuvel , linux-kernel@vger.kernel.org, Pekka Enberg , Daniel Micay , Casey Schaufler , Joonsoo Kim , linuxppc-dev@lists.ozlabs.org, "David S. Miller" MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP This creates per-architecture function arch_within_stack_frames() that should validate if a given object is contained by a kernel stack frame. Initial implementation is on x86. This is based on code from PaX. Signed-off-by: Kees Cook --- arch/Kconfig | 9 ++++++++ arch/x86/Kconfig | 1 + arch/x86/include/asm/thread_info.h | 44 ++++++++++++++++++++++++++++++++++++++ include/linux/thread_info.h | 9 ++++++++ 4 files changed, 63 insertions(+) diff --git a/arch/Kconfig b/arch/Kconfig index d794384a0404..5e2776562035 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -424,6 +424,15 @@ config CC_STACKPROTECTOR_STRONG endchoice +config HAVE_ARCH_WITHIN_STACK_FRAMES + bool + help + An architecture should select this if it can walk the kernel stack + frames to determine if an object is part of either the arguments + or local variables (i.e. that it excludes saved return addresses, + and similar) by implementing an inline arch_within_stack_frames(), + which is used by CONFIG_HARDENED_USERCOPY. + config HAVE_CONTEXT_TRACKING bool help diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 0a7b885964ba..4407f596b72c 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -91,6 +91,7 @@ config X86 select HAVE_ARCH_SOFT_DIRTY if X86_64 select HAVE_ARCH_TRACEHOOK select HAVE_ARCH_TRANSPARENT_HUGEPAGE + select HAVE_ARCH_WITHIN_STACK_FRAMES select HAVE_EBPF_JIT if X86_64 select HAVE_CC_STACKPROTECTOR select HAVE_CMPXCHG_DOUBLE diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index 30c133ac05cd..ab386f1336f2 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -180,6 +180,50 @@ static inline unsigned long current_stack_pointer(void) return sp; } +/* + * Walks up the stack frames to make sure that the specified object is + * entirely contained by a single stack frame. + * + * Returns: + * 1 if within a frame + * -1 if placed across a frame boundary (or outside stack) + * 0 unable to determine (no frame pointers, etc) + */ +static inline int arch_within_stack_frames(const void * const stack, + const void * const stackend, + const void *obj, unsigned long len) +{ +#if defined(CONFIG_FRAME_POINTER) + const void *frame = NULL; + const void *oldframe; + + oldframe = __builtin_frame_address(1); + if (oldframe) + frame = __builtin_frame_address(2); + /* + * low ----------------------------------------------> high + * [saved bp][saved ip][args][local vars][saved bp][saved ip] + * ^----------------^ + * allow copies only within here + */ + while (stack <= frame && frame < stackend) { + /* + * If obj + len extends past the last frame, this + * check won't pass and the next frame will be 0, + * causing us to bail out and correctly report + * the copy as invalid. + */ + if (obj + len <= frame) + return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1; + oldframe = frame; + frame = *(const void * const *)frame; + } + return -1; +#else + return 0; +#endif +} + #else /* !__ASSEMBLY__ */ #ifdef CONFIG_X86_64 diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index b4c2a485b28a..3d5c80b4391d 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -146,6 +146,15 @@ static inline bool test_and_clear_restore_sigmask(void) #error "no set_restore_sigmask() provided and default one won't work" #endif +#ifndef CONFIG_HAVE_ARCH_WITHIN_STACK_FRAMES +static inline int arch_within_stack_frames(const void * const stack, + const void * const stackend, + const void *obj, unsigned long len) +{ + return 0; +} +#endif + #endif /* __KERNEL__ */ #endif /* _LINUX_THREAD_INFO_H */