From patchwork Tue Jan 21 17:26:06 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laura Abbott X-Patchwork-Id: 3519121 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 94623C02DC for ; Tue, 21 Jan 2014 17:30:53 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id A31592013A for ; Tue, 21 Jan 2014 17:30:51 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id F315B20125 for ; Tue, 21 Jan 2014 17:30:49 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1W5f5z-0006hB-L1; Tue, 21 Jan 2014 17:26:39 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1W5f5x-0003qI-BN; Tue, 21 Jan 2014 17:26:37 +0000 Received: from smtp.codeaurora.org ([198.145.11.231]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1W5f5u-0003pL-1p for linux-arm-kernel@lists.infradead.org; Tue, 21 Jan 2014 17:26:35 +0000 Received: from smtp.codeaurora.org (localhost [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id EAFF613EDFB; Tue, 21 Jan 2014 17:26:11 +0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 486) id DE33613F14D; Tue, 21 Jan 2014 17:26:11 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-4.8 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 Received: from lauraa-linux1.qualcomm.com (i-global252.qualcomm.com [199.106.103.252]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: lauraa@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 3525313EDFB; Tue, 21 Jan 2014 17:26:11 +0000 (UTC) From: Laura Abbott To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] arm64: Add CONFIG_CC_STACKPROTECTOR Date: Tue, 21 Jan 2014 09:26:06 -0800 Message-Id: <1390325166-16840-1-git-send-email-lauraa@codeaurora.org> X-Mailer: git-send-email 1.7.8.3 X-Virus-Scanned: ClamAV using ClamSMTP X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140121_122634_234341_AB6A0EFE X-CRM114-Status: GOOD ( 23.03 ) X-Spam-Score: -2.5 (--) Cc: Will Deacon , Laura Abbott , Catalin Marinas X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 arm64 currently lacks support for -fstack-protector. Add similar functionality to arm to detect stack corruption. Cc: Will Deacon Cc: Catalin Marinas Signed-off-by: Laura Abbott --- arch/arm64/Kconfig | 12 +++++++++ arch/arm64/Makefile | 4 +++ arch/arm64/include/asm/stackprotector.h | 38 +++++++++++++++++++++++++++++++ arch/arm64/kernel/process.c | 9 +++++++ 4 files changed, 63 insertions(+), 0 deletions(-) create mode 100644 arch/arm64/include/asm/stackprotector.h diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 6d4dd22..4f86874 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -168,6 +168,18 @@ config HOTPLUG_CPU Say Y here to experiment with turning CPUs off and on. CPUs can be controlled through /sys/devices/system/cpu. +config CC_STACKPROTECTOR + bool "Enable -fstack-protector buffer overflow detection" + help + This option turns on the -fstack-protector GCC feature. This + feature puts, at the beginning of functions, a canary value on + the stack just before the return address, and validates + the value just before actually returning. Stack based buffer + overflows (that need to overwrite this return address) now also + overwrite the canary, which gets detected and the attack is then + neutralized via a kernel panic. + This feature requires gcc version 4.2 or above. + source kernel/Kconfig.preempt config HZ diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 2fceb71..1ce221e 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -48,6 +48,10 @@ core-$(CONFIG_XEN) += arch/arm64/xen/ libs-y := arch/arm64/lib/ $(libs-y) libs-y += $(LIBGCC) +ifeq ($(CONFIG_CC_STACKPROTECTOR),y) +KBUILD_CFLAGS +=-fstack-protector +endif + # Default target when executing plain make KBUILD_IMAGE := Image.gz KBUILD_DTBS := dtbs diff --git a/arch/arm64/include/asm/stackprotector.h b/arch/arm64/include/asm/stackprotector.h new file mode 100644 index 0000000..de00332 --- /dev/null +++ b/arch/arm64/include/asm/stackprotector.h @@ -0,0 +1,38 @@ +/* + * GCC stack protector support. + * + * Stack protector works by putting predefined pattern at the start of + * the stack frame and verifying that it hasn't been overwritten when + * returning from the function. The pattern is called stack canary + * and gcc expects it to be defined by a global variable called + * "__stack_chk_guard" on ARM. This unfortunately means that on SMP + * we cannot have a different canary value per task. + */ + +#ifndef _ASM_STACKPROTECTOR_H +#define _ASM_STACKPROTECTOR_H 1 + +#include +#include + +extern unsigned long __stack_chk_guard; + +/* + * Initialize the stackprotector canary value. + * + * NOTE: this must only be called from functions that never return, + * and it must always be inlined. + */ +static __always_inline void boot_init_stack_canary(void) +{ + unsigned long canary; + + /* Try to get a semi random initial value. */ + get_random_bytes(&canary, sizeof(canary)); + canary ^= LINUX_VERSION_CODE; + + current->stack_canary = canary; + __stack_chk_guard = current->stack_canary; +} + +#endif /* _ASM_STACKPROTECTOR_H */ diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index de17c89..592d630 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -50,6 +50,12 @@ #include #include +#ifdef CONFIG_CC_STACKPROTECTOR +#include +unsigned long __stack_chk_guard __read_mostly; +EXPORT_SYMBOL(__stack_chk_guard); +#endif + static void setup_restart(void) { /* @@ -288,6 +294,9 @@ struct task_struct *__switch_to(struct task_struct *prev, { struct task_struct *last; +#if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP) + __stack_chk_guard = next->stack_canary; +#endif fpsimd_thread_switch(next); tls_thread_switch(next); hw_breakpoint_thread_switch(next);