Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932889AbdC2SSb (ORCPT ); Wed, 29 Mar 2017 14:18:31 -0400 Received: from mail-pg0-f47.google.com ([74.125.83.47]:34458 "EHLO mail-pg0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932437AbdC2SQ0 (ORCPT ); Wed, 29 Mar 2017 14:16:26 -0400 From: Kees Cook To: kernel-hardening@lists.openwall.com Cc: Kees Cook , Mark Rutland , Andy Lutomirski , Hoeun Ryu , PaX Team , Emese Revfy , Russell King , x86@kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [RFC v2][PATCH 08/11] ARM: Implement __arch_rare_write_begin/end() Date: Wed, 29 Mar 2017 11:16:00 -0700 Message-Id: <1490811363-93944-9-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1490811363-93944-1-git-send-email-keescook@chromium.org> References: <1490811363-93944-1-git-send-email-keescook@chromium.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2743 Lines: 83 Based on grsecurity's ARM pax_{open,close}_kernel() implementation, this allows HAVE_ARCH_RARE_WRITE to work on ARM. Signed-off-by: Kees Cook --- arch/arm/Kconfig | 1 + arch/arm/include/asm/domain.h | 3 ++- arch/arm/include/asm/pgtable.h | 27 +++++++++++++++++++++++++++ 3 files changed, 30 insertions(+), 1 deletion(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 0d4e71b42c77..57b8aeaf501c 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -45,6 +45,7 @@ config ARM select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU select HAVE_ARCH_MMAP_RND_BITS if MMU + select HAVE_ARCH_RARE_WRITE if MMU && !ARM_LPAE && !CPU_USE_DOMAINS select HAVE_ARCH_SECCOMP_FILTER if (AEABI && !OABI_COMPAT) select HAVE_ARCH_TRACEHOOK select HAVE_ARM_SMCCC if CPU_V7 diff --git a/arch/arm/include/asm/domain.h b/arch/arm/include/asm/domain.h index b5ca80ac823c..b3fb5c0a2efd 100644 --- a/arch/arm/include/asm/domain.h +++ b/arch/arm/include/asm/domain.h @@ -54,6 +54,7 @@ #define DOMAIN_MANAGER 3 #else #define DOMAIN_MANAGER 1 +#define DOMAIN_FORCE_MANAGER 3 #endif #define domain_mask(dom) ((3) << (2 * (dom))) @@ -118,7 +119,7 @@ static inline void set_domain(unsigned val) } #endif -#ifdef CONFIG_CPU_USE_DOMAINS +#if defined(CONFIG_CPU_USE_DOMAINS) || defined(CONFIG_HAVE_ARCH_RARE_WRITE) #define modify_domain(dom,type) \ do { \ unsigned int domain = get_domain(); \ diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h index 1c462381c225..104923ea9eb5 100644 --- a/arch/arm/include/asm/pgtable.h +++ b/arch/arm/include/asm/pgtable.h @@ -57,6 +57,33 @@ extern void __pgd_error(const char *file, int line, pgd_t); #define pmd_ERROR(pmd) __pmd_error(__FILE__, __LINE__, pmd) #define pgd_ERROR(pgd) __pgd_error(__FILE__, __LINE__, pgd) +#ifdef CONFIG_HAVE_ARCH_RARE_WRITE +#include +#include + +static inline int test_domain(int domain, int domaintype) +{ + return (get_domain() & domain_val(domain, 3)) == + domain_val(domain, domaintype); +} + +static inline unsigned long __arch_rare_write_begin(void) +{ + preempt_disable(); + BUG_ON(test_domain(DOMAIN_WR_RARE, DOMAIN_FORCE_MANAGER)); + modify_domain(DOMAIN_WR_RARE, DOMAIN_FORCE_MANAGER); + return 0; +} + +static inline unsigned long __arch_rare_write_end(void) +{ + BUG_ON(test_domain(DOMAIN_WR_RARE, DOMAIN_CLIENT)); + modify_domain(DOMAIN_WR_RARE, DOMAIN_CLIENT); + preempt_enable_no_resched(); + return 0; +} +#endif + /* * This is the lowest virtual address we can permit any user space * mapping to be mapped at. This is particularly important for -- 2.7.4