From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Garnier Subject: [PATCH v3 2/4] x86/syscalls: Specific usage of verify_pre_usermode_state Date: Fri, 10 Mar 2017 16:04:59 -0800 Message-ID: <20170311000501.46607-2-thgarnie@google.com> References: <20170311000501.46607-1-thgarnie@google.com> Return-path: List-Post: List-Help: List-Unsubscribe: List-Subscribe: In-Reply-To: <20170311000501.46607-1-thgarnie@google.com> To: Martin Schwidefsky , Heiko Carstens , David Howells , Arnd Bergmann , Al Viro , Dave Hansen , Thomas Garnier , =?UTF-8?q?Ren=C3=A9=20Nyffenegger?= , Andrew Morton , Kees Cook , "Paul E . McKenney" , Andy Lutomirski , Ard Biesheuvel , Nicolas Pitre , Petr Mladek , Sebastian Andrzej Siewior , Sergey Senozhatsky , Helge Deller , Rik van Riel , Ingo Molnar , John Stultz , Thomas Gleixner 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 x86. --- Based on next-20170308 --- arch/x86/Kconfig | 1 + arch/x86/entry/common.c | 3 +++ arch/x86/entry/entry_64.S | 19 +++++++++++++++++++ arch/x86/include/asm/pgtable_64_types.h | 11 +++++++++++ arch/x86/include/asm/processor.h | 11 ----------- 5 files changed, 34 insertions(+), 11 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 005df7c825f5..6d48e18e6f09 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -63,6 +63,7 @@ config X86 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_MIGHT_HAVE_PC_SERIO + select ARCH_NO_SYSCALL_VERIFY_PRE_USERMODE_STATE select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 370c42c7f046..525edbb77f03 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include @@ -180,6 +181,8 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs) struct thread_info *ti = current_thread_info(); u32 cached_flags; + verify_pre_usermode_state(); + if (IS_ENABLED(CONFIG_PROVE_LOCKING) && WARN_ON(!irqs_disabled())) local_irq_disable(); diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index d2b2a2948ffe..04db589be466 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -218,6 +218,25 @@ entry_SYSCALL_64_fastpath: testl $_TIF_ALLWORK_MASK, TASK_TI_flags(%r11) jnz 1f + /* + * Check user-mode state on fast path return, the same check is done + * under the slow path through syscall_return_slowpath. + */ +#ifdef CONFIG_BUG_ON_DATA_CORRUPTION + call verify_pre_usermode_state +#else + /* + * Similar to set_fs(USER_DS) in verify_pre_usermode_state without a + * warning. + */ + movq PER_CPU_VAR(current_task), %rax + movq $TASK_SIZE_MAX, %rcx + cmp %rcx, TASK_addr_limit(%rax) + jz 1f + movq %rcx, TASK_addr_limit(%rax) +1: +#endif + LOCKDEP_SYS_EXIT TRACE_IRQS_ON /* user mode is traced as IRQs on */ movq RIP(%rsp), %rcx diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h index 3a264200c62f..0fbbb79d058c 100644 --- a/arch/x86/include/asm/pgtable_64_types.h +++ b/arch/x86/include/asm/pgtable_64_types.h @@ -76,4 +76,15 @@ typedef struct { pteval_t pte; } pte_t; #define EARLY_DYNAMIC_PAGE_TABLES 64 +/* + * User space process size. 47bits minus one guard page. The guard + * page is necessary on Intel CPUs: if a SYSCALL instruction is at + * the highest possible canonical userspace address, then that + * syscall will enter the kernel with a non-canonical return + * address, and SYSRET will explode dangerously. We avoid this + * particular problem by preventing anything from being mapped + * at the maximum canonical address. + */ +#define TASK_SIZE_MAX ((_AC(1, UL) << 47) - PAGE_SIZE) + #endif /* _ASM_X86_PGTABLE_64_DEFS_H */ diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index f385eca5407a..9bc99d37133e 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -829,17 +829,6 @@ static inline void spin_lock_prefetch(const void *x) #define KSTK_ESP(task) (task_pt_regs(task)->sp) #else -/* - * User space process size. 47bits minus one guard page. The guard - * page is necessary on Intel CPUs: if a SYSCALL instruction is at - * the highest possible canonical userspace address, then that - * syscall will enter the kernel with a non-canonical return - * address, and SYSRET will explode dangerously. We avoid this - * particular problem by preventing anything from being mapped - * at the maximum canonical address. - */ -#define TASK_SIZE_MAX ((1UL << 47) - PAGE_SIZE) - /* This decides where the kernel will search for a free chunk of vm * space during mmap's. */ -- 2.12.0.246.ga2ecc84866-goog From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Garnier Date: Fri, 10 Mar 2017 16:04:59 -0800 Message-Id: <20170311000501.46607-2-thgarnie@google.com> In-Reply-To: <20170311000501.46607-1-thgarnie@google.com> References: <20170311000501.46607-1-thgarnie@google.com> Subject: [kernel-hardening] [PATCH v3 2/4] x86/syscalls: Specific usage of verify_pre_usermode_state To: Martin Schwidefsky , Heiko Carstens , David Howells , Arnd Bergmann , Al Viro , Dave Hansen , Thomas Garnier , =?UTF-8?q?Ren=C3=A9=20Nyffenegger?= , Andrew Morton , Kees Cook , "Paul E . McKenney" , Andy Lutomirski , Ard Biesheuvel , Nicolas Pitre , Petr Mladek , Sebastian Andrzej Siewior , Sergey Senozhatsky , Helge Deller , Rik van Riel , Ingo Molnar , John Stultz , Thomas Gleixner , Oleg Nesterov , Stephen Smalley , Pavel Tikhomirov , Frederic Weisbecker , Stanislav Kinsburskiy , Ingo Molnar , "H . Peter Anvin" , Paolo Bonzini , Dmitry Safonov , Borislav Petkov , Josh Poimboeuf , Brian Gerst , Jan Beulich , Christian Borntraeger , Fenghua Yu , He Chen , Russell King , Vladimir Murzin , Will Deacon , Catalin Marinas , Mark Rutland , James Morse , "David A . Long" , Pratyush Anand , Laura Abbott , Andre Przywara , Chris Metcalf 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: Implement specific usage of verify_pre_usermode_state for user-mode returns for x86. --- Based on next-20170308 --- arch/x86/Kconfig | 1 + arch/x86/entry/common.c | 3 +++ arch/x86/entry/entry_64.S | 19 +++++++++++++++++++ arch/x86/include/asm/pgtable_64_types.h | 11 +++++++++++ arch/x86/include/asm/processor.h | 11 ----------- 5 files changed, 34 insertions(+), 11 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 005df7c825f5..6d48e18e6f09 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -63,6 +63,7 @@ config X86 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_MIGHT_HAVE_PC_SERIO + select ARCH_NO_SYSCALL_VERIFY_PRE_USERMODE_STATE select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 370c42c7f046..525edbb77f03 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include @@ -180,6 +181,8 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs) struct thread_info *ti = current_thread_info(); u32 cached_flags; + verify_pre_usermode_state(); + if (IS_ENABLED(CONFIG_PROVE_LOCKING) && WARN_ON(!irqs_disabled())) local_irq_disable(); diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index d2b2a2948ffe..04db589be466 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -218,6 +218,25 @@ entry_SYSCALL_64_fastpath: testl $_TIF_ALLWORK_MASK, TASK_TI_flags(%r11) jnz 1f + /* + * Check user-mode state on fast path return, the same check is done + * under the slow path through syscall_return_slowpath. + */ +#ifdef CONFIG_BUG_ON_DATA_CORRUPTION + call verify_pre_usermode_state +#else + /* + * Similar to set_fs(USER_DS) in verify_pre_usermode_state without a + * warning. + */ + movq PER_CPU_VAR(current_task), %rax + movq $TASK_SIZE_MAX, %rcx + cmp %rcx, TASK_addr_limit(%rax) + jz 1f + movq %rcx, TASK_addr_limit(%rax) +1: +#endif + LOCKDEP_SYS_EXIT TRACE_IRQS_ON /* user mode is traced as IRQs on */ movq RIP(%rsp), %rcx diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h index 3a264200c62f..0fbbb79d058c 100644 --- a/arch/x86/include/asm/pgtable_64_types.h +++ b/arch/x86/include/asm/pgtable_64_types.h @@ -76,4 +76,15 @@ typedef struct { pteval_t pte; } pte_t; #define EARLY_DYNAMIC_PAGE_TABLES 64 +/* + * User space process size. 47bits minus one guard page. The guard + * page is necessary on Intel CPUs: if a SYSCALL instruction is at + * the highest possible canonical userspace address, then that + * syscall will enter the kernel with a non-canonical return + * address, and SYSRET will explode dangerously. We avoid this + * particular problem by preventing anything from being mapped + * at the maximum canonical address. + */ +#define TASK_SIZE_MAX ((_AC(1, UL) << 47) - PAGE_SIZE) + #endif /* _ASM_X86_PGTABLE_64_DEFS_H */ diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index f385eca5407a..9bc99d37133e 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -829,17 +829,6 @@ static inline void spin_lock_prefetch(const void *x) #define KSTK_ESP(task) (task_pt_regs(task)->sp) #else -/* - * User space process size. 47bits minus one guard page. The guard - * page is necessary on Intel CPUs: if a SYSCALL instruction is at - * the highest possible canonical userspace address, then that - * syscall will enter the kernel with a non-canonical return - * address, and SYSRET will explode dangerously. We avoid this - * particular problem by preventing anything from being mapped - * at the maximum canonical address. - */ -#define TASK_SIZE_MAX ((1UL << 47) - PAGE_SIZE) - /* This decides where the kernel will search for a free chunk of vm * space during mmap's. */ -- 2.12.0.246.ga2ecc84866-goog