From patchwork Wed Jul 13 21:55:54 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 9228509 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 151E960868 for ; Wed, 13 Jul 2016 21:56:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E7AFA28307 for ; Wed, 13 Jul 2016 21:56:36 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C74AC28325; Wed, 13 Jul 2016 21:56:36 +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 9867428307 for ; Wed, 13 Jul 2016 21:56:35 +0000 (UTC) Received: (qmail 17545 invoked by uid 550); 13 Jul 2016 21:56:27 -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 17521 invoked from network); 13 Jul 2016 21:56:26 -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=m6ZMyPSI+wnfFONnWfXh8nbvuRtK/xUyUwlZueocUkg=; b=IXOR8aH4/ht41E27EkanLpYNEnTNfOnMpEpY37iCDu3CZf6Yo2hQivAl3XIkfyEt1E bL9qQiW4qrLNwu7z5CAHI3Z0JUX+RMVv8SsVbebwmNVgvjqXB5mAMAD2T/9U13VGYvXD 9h1TRz+6hhjQ5+c7BRUZUG7oI0SaY2hr7jtuU= 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=aL8k0hYpRwITiAO0U2E4r1JprgVEGWI4qCIysPZltwqChy4UWoXB5fb+bv/F2vrEM4 z8mzT2LVVwdd+k9UN61LvR7yLNv9iwS6VSzZpKcvcwPyZfZtJT+pym5zAoJYZs4h4Yqi gHz+3F2o0/zYZ2hSMfuUrDiA2p6MKnc2S/R/0Hj+cqstMvuvL8Ow0ffO9pvE6fzgGZaP 8vRqTK4BMCSIaWxfC/lAcfhiCn9r0ChfV9hYfPd6SbABd8Re+YEd6AMHbBPkNrzsRp4d 7jMm+0Et0vT4gx5YA8NFW+roYWEYzcfx+AKt9Gw0h0sRTHPcx7aIvINgVUK0TAqu92uD kKYg== X-Gm-Message-State: ALyK8tLCQcUI5lIrcpfXCsQ0CHdzaYtzl7IzGgL7p1m7NT0x8WdwT89zW1zIweAt7ZTqvs0x X-Received: by 10.66.123.42 with SMTP id lx10mr17005435pab.95.1468446974669; Wed, 13 Jul 2016 14:56:14 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , Rik van Riel , Casey Schaufler , PaX Team , Brad Spengler , Russell King , Catalin Marinas , Will Deacon , Ard Biesheuvel , Benjamin Herrenschmidt , Michael Ellerman , Tony Luck , Fenghua Yu , "David S. Miller" , x86@kernel.org, Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Andy Lutomirski , Borislav Petkov , Mathias Krause , Jan Kara , Vitaly Wool , Andrea Arcangeli , Dmitry Vyukov , Laura Abbott , linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com Date: Wed, 13 Jul 2016 14:55:54 -0700 Message-Id: <1468446964-22213-2-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1468446964-22213-1-git-send-email-keescook@chromium.org> References: <1468446964-22213-1-git-send-email-keescook@chromium.org> Subject: [kernel-hardening] [PATCH v2 01/11] mm: Implement stack frame object validation 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 */