From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Garnier Subject: [PATCH v4 3/4] arm/syscalls: Specific usage of verify_pre_usermode_state Date: Wed, 22 Mar 2017 13:38:33 -0700 Message-ID: <20170322203834.67556-3-thgarnie@google.com> References: <20170322203834.67556-1-thgarnie@google.com> Return-path: List-Post: List-Help: List-Unsubscribe: List-Subscribe: In-Reply-To: <20170322203834.67556-1-thgarnie@google.com> To: Martin Schwidefsky , Heiko Carstens , Dave Hansen , David Howells , Al Viro , Arnd Bergmann , Thomas Garnier , =?UTF-8?q?Ren=C3=A9=20Nyffenegger?= , Andrew Morton , "Paul E . McKenney" , Ingo Molnar , Thomas Gleixner , Oleg Nesterov , Pavel Tikhomirov , Stephen Smalley , Ingo Molnar , "H . Peter Anvin" , Andy Lutomirski , Paolo Bonzini , Rik van Riel , Kees Cook , Josh Poimboeuf , Borislav Petkov Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, kernel-hardening@lists.openwall.com List-Id: linux-api@vger.kernel.org Implement specific usage of verify_pre_usermode_state for user-mode returns for arm. --- Based on next-20170322 --- arch/arm/Kconfig | 1 + arch/arm/include/asm/domain.h | 3 +++ arch/arm/kernel/entry-common.S | 32 +++++++++++++++++++++++++++++++- 3 files changed, 35 insertions(+), 1 deletion(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index fcbc5ef1ec69..10c6dc3dfff9 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -12,6 +12,7 @@ config ARM select ARCH_HAVE_CUSTOM_GPIO_H select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_MIGHT_HAVE_PC_PARPORT + select ARCH_NO_SYSCALL_VERIFY_PRE_USERMODE_STATE select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7 select ARCH_SUPPORTS_ATOMIC_RMW diff --git a/arch/arm/include/asm/domain.h b/arch/arm/include/asm/domain.h index 99d9f630d6b6..fd1cd24ca9fe 100644 --- a/arch/arm/include/asm/domain.h +++ b/arch/arm/include/asm/domain.h @@ -58,6 +58,9 @@ #define domain_mask(dom) ((3) << (2 * (dom))) #define domain_val(dom,type) ((type) << (2 * (dom))) +#define DOMAIN_KERNEL_MASK domain_mask(DOMAIN_KERNEL) +#define DOMAIN_CLIENT_VALUE domain_val(DOMAIN_KERNEL, DOMAIN_CLIENT) + #ifdef CONFIG_CPU_SW_DOMAIN_PAN #define DACR_INIT \ (domain_val(DOMAIN_USER, DOMAIN_NOACCESS) | \ diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index eb5cd77bf1d8..8d9bfe9ff313 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -12,6 +12,7 @@ #include #include #include +#include #ifdef CONFIG_AEABI #include #endif @@ -27,7 +28,6 @@ #include "entry-header.S" - .align 5 #if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING)) /* @@ -40,9 +40,12 @@ ret_fast_syscall: UNWIND(.fnstart ) UNWIND(.cantunwind ) disable_irq_notrace @ disable interrupts + ldr r2, [tsk, #TI_ADDR_LIMIT] ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK bne fast_work_pending + cmp r2, #TASK_SIZE + blne addr_limit_fail /* perform architecture specific actions before user return */ arch_ret_to_user r1, lr @@ -66,6 +69,7 @@ ret_fast_syscall: UNWIND(.cantunwind ) str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 disable_irq_notrace @ disable interrupts + ldr r2, [tsk, #TI_ADDR_LIMIT] ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK beq no_work_pending @@ -82,6 +86,7 @@ slow_work_pending: mov r2, why @ 'syscall' bl do_work_pending cmp r0, #0 + ldreq r2, [tsk, #TI_ADDR_LIMIT] beq no_work_pending movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) ldmia sp, {r0 - r6} @ have to reload r0 - r6 @@ -99,9 +104,12 @@ ret_slow_syscall: disable_irq_notrace @ disable interrupts ENTRY(ret_to_user_from_irq) ldr r1, [tsk, #TI_FLAGS] + ldr r2, [tsk, #TI_ADDR_LIMIT] tst r1, #_TIF_WORK_MASK bne slow_work_pending no_work_pending: + cmp r2, #TASK_SIZE + blne addr_limit_fail asm_trace_hardirqs_on save = 0 /* perform architecture specific actions before user return */ @@ -125,6 +133,28 @@ ENTRY(ret_from_fork) b ret_slow_syscall ENDPROC(ret_from_fork) +addr_limit_fail: +#ifdef CONFIG_BUG_ON_DATA_CORRUPTION + stmfd sp!, {r0, lr} + bl verify_pre_usermode_state + ldmfd sp!, {r0, lr} +#else + /* + * Similar to set_fs(USER_DS) in verify_pre_usermode_state without a + * warning. + */ + mov r2, #TASK_SIZE + str r2, [tsk, #TI_ADDR_LIMIT] +#ifdef CONFIG_CPU_USE_DOMAINS + /* Switch domain like modify_domain(DOMAIN_KERNEL, DOMAIN_CLIENT) */ + mrc p15, 0, r2, c3, c0, 0 @ Get domain register + bic r2, r2, #DOMAIN_KERNEL_MASK @ Clear the domain part + orr r2, r2, #DOMAIN_CLIENT_VALUE @ Enforce DOMAIN_CLIENT + mcr p15, 0, r2, c3, c0, 0 @ Set domain register +#endif +#endif + ret lr + /*============================================================================= * SWI handler *----------------------------------------------------------------------------- -- 2.12.1.500.gab5fba24ee-goog