From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Garnier Subject: [PATCH v2 4/4] arm64/syscalls: Specific usage of verify_pre_usermode_state Date: Wed, 8 Mar 2017 17:24:56 -0800 Message-ID: <20170309012456.5631-4-thgarnie@google.com> References: <20170309012456.5631-1-thgarnie@google.com> Return-path: List-Post: List-Help: List-Unsubscribe: List-Subscribe: In-Reply-To: <20170309012456.5631-1-thgarnie@google.com> To: David Howells , Dave Hansen , Arnd Bergmann , Al Viro , =?UTF-8?q?Ren=C3=A9=20Nyffenegger?= , Thomas Garnier , Andrew Morton , Kees Cook , "Paul E . McKenney" , "David S . Miller" , Andy Lutomirski , Ard Biesheuvel , Nicolas Pitre , Petr Mladek , Sebastian Andrzej Siewior , Sergey Senozhatsky , Helge Deller , Rik van Riel , Ingo Molnar , Oleg Nesterov , John Stultz , Thomas Gleixner , Pavel Cc: linux-api@vger.kernel.org, linux-kernel@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 arm64. --- Based on next-20170308 --- arch/arm64/Kconfig | 1 + arch/arm64/kernel/entry.S | 15 +++++++++++++++ 2 files changed, 16 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 896eba61e5ed..da54774838d8 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -24,6 +24,7 @@ config ARM64 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION select ARCH_WANT_FRAME_POINTERS select ARCH_HAS_UBSAN_SANITIZE_ALL + select ARCH_NO_SYSCALL_VERIFY_PRE_USERMODE_STATE select ARM_AMBA select ARM_ARCH_TIMER select ARM_GIC diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 43512d4d7df2..eca392ae63e9 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -737,6 +737,19 @@ ENTRY(cpu_switch_to) ret ENDPROC(cpu_switch_to) +#ifdef CONFIG_BUG_ON_DATA_CORRUPTION +.macro VERIFY_PRE_USERMODE_STATE + bl verify_pre_usermode_state +.endm +#else +/* Similar to set_fs(USER_DS) in verify_pre_usermode_state without a warning. */ +.macro VERIFY_PRE_USERMODE_STATE + mov x1, #TASK_SIZE_64 + str x1, [tsk, #TSK_TI_ADDR_LIMIT] +.endm +#endif + + /* * This is the fast syscall return path. We do as little as possible here, * and this includes saving x0 back into the kernel stack. @@ -744,6 +757,7 @@ ENDPROC(cpu_switch_to) ret_fast_syscall: disable_irq // disable interrupts str x0, [sp, #S_X0] // returned x0 + VERIFY_PRE_USERMODE_STATE ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for syscall tracing and x2, x1, #_TIF_SYSCALL_WORK cbnz x2, ret_fast_syscall_trace @@ -771,6 +785,7 @@ work_pending: */ ret_to_user: disable_irq // disable interrupts + VERIFY_PRE_USERMODE_STATE ldr x1, [tsk, #TSK_TI_FLAGS] and x2, x1, #_TIF_WORK_MASK cbnz x2, work_pending -- 2.12.0.246.ga2ecc84866-goog