| Message ID | 20180718211013.14512-3-labbott@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jul 18, 2018 at 2:10 PM, Laura Abbott <labbott@redhat.com> wrote: > > Implementation of stackleak based heavily on the x86 version > > Signed-off-by: Laura Abbott <labbott@redhat.com> > --- > Since last time: Minor style cleanups. Re-wrote check_alloca to > correctly handle all stack types. While doing that, I also realized > current_top_of_stack was incorrect so I fixed that as well. Can you drop the include/linux/stackleak.h change from this series? I've included that in the v14 in linux-next already, so that these patches can land entirely separately in the arm64 tree (which was the request). Otherwise, this looks great! Reviewed-by: Kees Cook <keescook@chromium.org> -Kees > --- > arch/arm64/Kconfig | 1 + > arch/arm64/include/asm/processor.h | 17 ++++++++++++++ > arch/arm64/kernel/entry.S | 7 ++++++ > arch/arm64/kernel/process.c | 32 +++++++++++++++++++++++++++ > arch/arm64/kvm/hyp/Makefile | 3 ++- > drivers/firmware/efi/libstub/Makefile | 3 ++- > include/linux/stackleak.h | 1 + > 7 files changed, 62 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 42c090cf0292..216d36a49ab5 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -96,6 +96,7 @@ config ARM64 > select HAVE_ARCH_MMAP_RND_BITS > select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT > select HAVE_ARCH_SECCOMP_FILTER > + select HAVE_ARCH_STACKLEAK > select HAVE_ARCH_THREAD_STRUCT_WHITELIST > select HAVE_ARCH_TRACEHOOK > select HAVE_ARCH_TRANSPARENT_HUGEPAGE > diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h > index a73ae1e49200..4f3062ee22c6 100644 > --- a/arch/arm64/include/asm/processor.h > +++ b/arch/arm64/include/asm/processor.h > @@ -266,5 +266,22 @@ extern void __init minsigstksz_setup(void); > #define SVE_SET_VL(arg) sve_set_current_vl(arg) > #define SVE_GET_VL() sve_get_current_vl() > > +/* > + * For CONFIG_STACKLEAK > + * > + * These need to be macros because otherwise we get stuck in a nightmare > + * of header definitions for the use of task_stack_page. > + */ > + > +#define current_top_of_stack() \ > +({ \ > + unsigned long _low = 0; \ > + unsigned long _high = 0; \ > + \ > + current_stack_type(current, current_stack_pointer, &_low, &_high); \ > + _high; \ > +}) > +#define on_thread_stack() (on_task_stack(current, current_stack_pointer, NULL, NULL)) > + > #endif /* __ASSEMBLY__ */ > #endif /* __ASM_PROCESSOR_H */ > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index 28ad8799406f..67d12016063d 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -431,6 +431,11 @@ tsk .req x28 // current thread_info > > .text > > + .macro stackleak_erase > +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK > + bl stackleak_erase > +#endif > + .endm > /* > * Exception vectors. > */ > @@ -910,6 +915,7 @@ ret_fast_syscall: > and x2, x1, #_TIF_WORK_MASK > cbnz x2, work_pending > enable_step_tsk x1, x2 > + stackleak_erase > kernel_exit 0 > ret_fast_syscall_trace: > enable_daif > @@ -936,6 +942,7 @@ ret_to_user: > cbnz x2, work_pending > finish_ret_to_user: > enable_step_tsk x1, x2 > + stackleak_erase > kernel_exit 0 > ENDPROC(ret_to_user) > > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c > index e10bc363f533..904defa36689 100644 > --- a/arch/arm64/kernel/process.c > +++ b/arch/arm64/kernel/process.c > @@ -493,3 +493,35 @@ void arch_setup_new_exec(void) > { > current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0; > } > + > +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK > +void __used stackleak_check_alloca(unsigned long size) > +{ > + unsigned long stack_left; > + enum stack_type type; > + unsigned long current_sp = current_stack_pointer; > + unsigned long low, high; > + > + type = current_stack_type(current, current_sp, &low, &high); > + BUG_ON(type == STACK_TYPE_UNKNOWN); > + > + stack_left = current_sp - low; > + > + if (size >= stack_left) { > + /* > + * Kernel stack depth overflow is detected, let's report that. > + * If CONFIG_VMAP_STACK is enabled, we can safely use BUG(). > + * If CONFIG_VMAP_STACK is disabled, BUG() handling can corrupt > + * the neighbour memory. CONFIG_SCHED_STACK_END_CHECK calls > + * panic() in a similar situation, so let's do the same if that > + * option is on. Otherwise just use BUG() and hope for the best. > + */ > +#if !defined(CONFIG_VMAP_STACK) && defined(CONFIG_SCHED_STACK_END_CHECK) > + panic("alloca() over the kernel stack boundary\n"); > +#else > + BUG(); > +#endif > + } > +} > +EXPORT_SYMBOL(stackleak_check_alloca); > +#endif > diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile > index 4313f7475333..2fabc2dc1966 100644 > --- a/arch/arm64/kvm/hyp/Makefile > +++ b/arch/arm64/kvm/hyp/Makefile > @@ -3,7 +3,8 @@ > # Makefile for Kernel-based Virtual Machine module, HYP part > # > > -ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING > +ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING \ > + $(DISABLE_STACKLEAK_PLUGIN) > > KVM=../../../../virt/kvm > > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile > index a34e9290a699..25dd2a14560d 100644 > --- a/drivers/firmware/efi/libstub/Makefile > +++ b/drivers/firmware/efi/libstub/Makefile > @@ -20,7 +20,8 @@ cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt > KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \ > -D__NO_FORTIFY \ > $(call cc-option,-ffreestanding) \ > - $(call cc-option,-fno-stack-protector) > + $(call cc-option,-fno-stack-protector) \ > + $(DISABLE_STACKLEAK_PLUGIN) > > GCOV_PROFILE := n > KASAN_SANITIZE := n > diff --git a/include/linux/stackleak.h b/include/linux/stackleak.h > index b911b973d328..08420ec6b7c3 100644 > --- a/include/linux/stackleak.h > +++ b/include/linux/stackleak.h > @@ -5,6 +5,7 @@ > #include <linux/sched.h> > #include <linux/sched/task_stack.h> > > +#include <asm/stacktrace.h> > /* > * Check that the poison value points to the unused hole in the > * virtual memory map for your platform. > -- > 2.17.1 >
Hello Laura, Thanks again for your work. Please see some comments below. On 19.07.2018 00:10, Laura Abbott wrote: > Implementation of stackleak based heavily on the x86 version > > Signed-off-by: Laura Abbott <labbott@redhat.com> > --- > Since last time: Minor style cleanups. Re-wrote check_alloca to > correctly handle all stack types. While doing that, I also realized > current_top_of_stack was incorrect so I fixed that as well. > --- > arch/arm64/Kconfig | 1 + > arch/arm64/include/asm/processor.h | 17 ++++++++++++++ > arch/arm64/kernel/entry.S | 7 ++++++ > arch/arm64/kernel/process.c | 32 +++++++++++++++++++++++++++ > arch/arm64/kvm/hyp/Makefile | 3 ++- > drivers/firmware/efi/libstub/Makefile | 3 ++- > include/linux/stackleak.h | 1 + > 7 files changed, 62 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 42c090cf0292..216d36a49ab5 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -96,6 +96,7 @@ config ARM64 > select HAVE_ARCH_MMAP_RND_BITS > select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT > select HAVE_ARCH_SECCOMP_FILTER > + select HAVE_ARCH_STACKLEAK > select HAVE_ARCH_THREAD_STRUCT_WHITELIST > select HAVE_ARCH_TRACEHOOK > select HAVE_ARCH_TRANSPARENT_HUGEPAGE > diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h > index a73ae1e49200..4f3062ee22c6 100644 > --- a/arch/arm64/include/asm/processor.h > +++ b/arch/arm64/include/asm/processor.h > @@ -266,5 +266,22 @@ extern void __init minsigstksz_setup(void); > #define SVE_SET_VL(arg) sve_set_current_vl(arg) > #define SVE_GET_VL() sve_get_current_vl() > > +/* > + * For CONFIG_STACKLEAK Our config option is called CONFIG_GCC_PLUGIN_STACKLEAK. > + * > + * These need to be macros because otherwise we get stuck in a nightmare > + * of header definitions for the use of task_stack_page. > + */ > + > +#define current_top_of_stack() \ > +({ \ > + unsigned long _low = 0; \ > + unsigned long _high = 0; \ > + \ > + current_stack_type(current, current_stack_pointer, &_low, &_high); \ > + _high; \ > +}) Do you really need _low here? Ah, I see this in the previous patch: + if (stack_low && stack_high) { + *stack_low = low; + *stack_high = high; + } How about checking them against NULL separately? That would allow + current_stack_type(current, current_stack_pointer, NULL, &_high); Also a minor comment - how about aligning backslashes? > +#define on_thread_stack() (on_task_stack(current, current_stack_pointer, NULL, NULL)) > + > #endif /* __ASSEMBLY__ */ > #endif /* __ASM_PROCESSOR_H */ > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index 28ad8799406f..67d12016063d 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -431,6 +431,11 @@ tsk .req x28 // current thread_info > > .text > > + .macro stackleak_erase > +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK > + bl stackleak_erase > +#endif > + .endm > /* > * Exception vectors. > */ > @@ -910,6 +915,7 @@ ret_fast_syscall: > and x2, x1, #_TIF_WORK_MASK > cbnz x2, work_pending > enable_step_tsk x1, x2 > + stackleak_erase > kernel_exit 0 > ret_fast_syscall_trace: > enable_daif > @@ -936,6 +942,7 @@ ret_to_user: > cbnz x2, work_pending > finish_ret_to_user: > enable_step_tsk x1, x2 > + stackleak_erase > kernel_exit 0 > ENDPROC(ret_to_user) > > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c > index e10bc363f533..904defa36689 100644 > --- a/arch/arm64/kernel/process.c > +++ b/arch/arm64/kernel/process.c > @@ -493,3 +493,35 @@ void arch_setup_new_exec(void) > { > current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0; > } > + > +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK > +void __used stackleak_check_alloca(unsigned long size) > +{ > + unsigned long stack_left; > + enum stack_type type; > + unsigned long current_sp = current_stack_pointer; > + unsigned long low, high; > + > + type = current_stack_type(current, current_sp, &low, &high); > + BUG_ON(type == STACK_TYPE_UNKNOWN); > + > + stack_left = current_sp - low; > + > + if (size >= stack_left) { > + /* > + * Kernel stack depth overflow is detected, let's report that. > + * If CONFIG_VMAP_STACK is enabled, we can safely use BUG(). > + * If CONFIG_VMAP_STACK is disabled, BUG() handling can corrupt > + * the neighbour memory. CONFIG_SCHED_STACK_END_CHECK calls > + * panic() in a similar situation, so let's do the same if that > + * option is on. Otherwise just use BUG() and hope for the best. > + */ > +#if !defined(CONFIG_VMAP_STACK) && defined(CONFIG_SCHED_STACK_END_CHECK) > + panic("alloca() over the kernel stack boundary\n"); > +#else > + BUG(); > +#endif This comment and #if logic should be dropped, we should always use panic() here on arm64. Mark Rutland and I have worked out the solution for arm64 in this thread: http://openwall.com/lists/kernel-hardening/2018/05/11/12 Rationale: on arm64 with CONFIG_VMAP_STACK, a stack overflow results in panic() anyway. > + } > +} > +EXPORT_SYMBOL(stackleak_check_alloca); > +#endif > diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile > index 4313f7475333..2fabc2dc1966 100644 > --- a/arch/arm64/kvm/hyp/Makefile > +++ b/arch/arm64/kvm/hyp/Makefile > @@ -3,7 +3,8 @@ > # Makefile for Kernel-based Virtual Machine module, HYP part > # > > -ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING > +ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING \ > + $(DISABLE_STACKLEAK_PLUGIN) > > KVM=../../../../virt/kvm > > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile > index a34e9290a699..25dd2a14560d 100644 > --- a/drivers/firmware/efi/libstub/Makefile > +++ b/drivers/firmware/efi/libstub/Makefile > @@ -20,7 +20,8 @@ cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt > KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \ > -D__NO_FORTIFY \ > $(call cc-option,-ffreestanding) \ > - $(call cc-option,-fno-stack-protector) > + $(call cc-option,-fno-stack-protector) \ > + $(DISABLE_STACKLEAK_PLUGIN) > > GCOV_PROFILE := n > KASAN_SANITIZE := n > diff --git a/include/linux/stackleak.h b/include/linux/stackleak.h > index b911b973d328..08420ec6b7c3 100644 > --- a/include/linux/stackleak.h > +++ b/include/linux/stackleak.h > @@ -5,6 +5,7 @@ > #include <linux/sched.h> > #include <linux/sched/task_stack.h> > > +#include <asm/stacktrace.h> > /* > * Check that the poison value points to the unused hole in the > * virtual memory map for your platform. >
On Wed, Jul 18, 2018 at 02:10:13PM -0700, Laura Abbott wrote: > > Implementation of stackleak based heavily on the x86 version > > Signed-off-by: Laura Abbott <labbott@redhat.com> > --- > Since last time: Minor style cleanups. Re-wrote check_alloca to > correctly handle all stack types. While doing that, I also realized > current_top_of_stack was incorrect so I fixed that as well. > --- > arch/arm64/Kconfig | 1 + > arch/arm64/include/asm/processor.h | 17 ++++++++++++++ > arch/arm64/kernel/entry.S | 7 ++++++ > arch/arm64/kernel/process.c | 32 +++++++++++++++++++++++++++ > arch/arm64/kvm/hyp/Makefile | 3 ++- > drivers/firmware/efi/libstub/Makefile | 3 ++- > include/linux/stackleak.h | 1 + > 7 files changed, 62 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 42c090cf0292..216d36a49ab5 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -96,6 +96,7 @@ config ARM64 > select HAVE_ARCH_MMAP_RND_BITS > select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT > select HAVE_ARCH_SECCOMP_FILTER > + select HAVE_ARCH_STACKLEAK > select HAVE_ARCH_THREAD_STRUCT_WHITELIST > select HAVE_ARCH_TRACEHOOK > select HAVE_ARCH_TRANSPARENT_HUGEPAGE > diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h > index a73ae1e49200..4f3062ee22c6 100644 > --- a/arch/arm64/include/asm/processor.h > +++ b/arch/arm64/include/asm/processor.h > @@ -266,5 +266,22 @@ extern void __init minsigstksz_setup(void); > #define SVE_SET_VL(arg) sve_set_current_vl(arg) > #define SVE_GET_VL() sve_get_current_vl() > > +/* > + * For CONFIG_STACKLEAK > + * > + * These need to be macros because otherwise we get stuck in a nightmare > + * of header definitions for the use of task_stack_page. > + */ > + > +#define current_top_of_stack() \ > +({ \ > + unsigned long _low = 0; \ > + unsigned long _high = 0; \ > + \ > + current_stack_type(current, current_stack_pointer, &_low, &_high); \ > + _high; \ > +}) ... with the info changes, this could be: #define current_top_of_stack() \ ({ \ struct stack_info _info; \ BUG_ON(!on_accessible_stack(current_stack_pinter, &_info)); \ _info->high; \ }) > +#define on_thread_stack() (on_task_stack(current, current_stack_pointer, NULL, NULL)) ... and one fewer NULL here. > + > #endif /* __ASSEMBLY__ */ > #endif /* __ASM_PROCESSOR_H */ > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index 28ad8799406f..67d12016063d 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -431,6 +431,11 @@ tsk .req x28 // current thread_info > > .text > > + .macro stackleak_erase > +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK > + bl stackleak_erase > +#endif > + .endm > /* > * Exception vectors. > */ > @@ -910,6 +915,7 @@ ret_fast_syscall: > and x2, x1, #_TIF_WORK_MASK > cbnz x2, work_pending > enable_step_tsk x1, x2 > + stackleak_erase > kernel_exit 0 > ret_fast_syscall_trace: > enable_daif > @@ -936,6 +942,7 @@ ret_to_user: > cbnz x2, work_pending > finish_ret_to_user: > enable_step_tsk x1, x2 > + stackleak_erase > kernel_exit 0 > ENDPROC(ret_to_user) > > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c > index e10bc363f533..904defa36689 100644 > --- a/arch/arm64/kernel/process.c > +++ b/arch/arm64/kernel/process.c > @@ -493,3 +493,35 @@ void arch_setup_new_exec(void) > { > current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0; > } > + > +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK > +void __used stackleak_check_alloca(unsigned long size) > +{ > + unsigned long stack_left; > + enum stack_type type; > + unsigned long current_sp = current_stack_pointer; > + unsigned long low, high; > + > + type = current_stack_type(current, current_sp, &low, &high); > + BUG_ON(type == STACK_TYPE_UNKNOWN); > + > + stack_left = current_sp - low; ... similarly with the info changes, this could be: unsigned long current_sp = current_stack_pointer; unsigned long stack_left; struct stack_info info; BUG_ON(!on_accessible_stack(current, current_sp, &info)); stack_lead = current_sp - info->low; Otherwise, this looks good to me. Thanks, Mark. > + > + if (size >= stack_left) { > + /* > + * Kernel stack depth overflow is detected, let's report that. > + * If CONFIG_VMAP_STACK is enabled, we can safely use BUG(). > + * If CONFIG_VMAP_STACK is disabled, BUG() handling can corrupt > + * the neighbour memory. CONFIG_SCHED_STACK_END_CHECK calls > + * panic() in a similar situation, so let's do the same if that > + * option is on. Otherwise just use BUG() and hope for the best. > + */ > +#if !defined(CONFIG_VMAP_STACK) && defined(CONFIG_SCHED_STACK_END_CHECK) > + panic("alloca() over the kernel stack boundary\n"); > +#else > + BUG(); > +#endif > + } > +} > +EXPORT_SYMBOL(stackleak_check_alloca); > +#endif > diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile > index 4313f7475333..2fabc2dc1966 100644 > --- a/arch/arm64/kvm/hyp/Makefile > +++ b/arch/arm64/kvm/hyp/Makefile > @@ -3,7 +3,8 @@ > # Makefile for Kernel-based Virtual Machine module, HYP part > # > > -ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING > +ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING \ > + $(DISABLE_STACKLEAK_PLUGIN) > > KVM=../../../../virt/kvm > > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile > index a34e9290a699..25dd2a14560d 100644 > --- a/drivers/firmware/efi/libstub/Makefile > +++ b/drivers/firmware/efi/libstub/Makefile > @@ -20,7 +20,8 @@ cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt > KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \ > -D__NO_FORTIFY \ > $(call cc-option,-ffreestanding) \ > - $(call cc-option,-fno-stack-protector) > + $(call cc-option,-fno-stack-protector) \ > + $(DISABLE_STACKLEAK_PLUGIN) > > GCOV_PROFILE := n > KASAN_SANITIZE := n > diff --git a/include/linux/stackleak.h b/include/linux/stackleak.h > index b911b973d328..08420ec6b7c3 100644 > --- a/include/linux/stackleak.h > +++ b/include/linux/stackleak.h > @@ -5,6 +5,7 @@ > #include <linux/sched.h> > #include <linux/sched/task_stack.h> > > +#include <asm/stacktrace.h> > /* > * Check that the poison value points to the unused hole in the > * virtual memory map for your platform. > -- > 2.17.1 >
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 42c090cf0292..216d36a49ab5 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -96,6 +96,7 @@ config ARM64 select HAVE_ARCH_MMAP_RND_BITS select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT select HAVE_ARCH_SECCOMP_FILTER + select HAVE_ARCH_STACKLEAK select HAVE_ARCH_THREAD_STRUCT_WHITELIST select HAVE_ARCH_TRACEHOOK select HAVE_ARCH_TRANSPARENT_HUGEPAGE diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index a73ae1e49200..4f3062ee22c6 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -266,5 +266,22 @@ extern void __init minsigstksz_setup(void); #define SVE_SET_VL(arg) sve_set_current_vl(arg) #define SVE_GET_VL() sve_get_current_vl() +/* + * For CONFIG_STACKLEAK + * + * These need to be macros because otherwise we get stuck in a nightmare + * of header definitions for the use of task_stack_page. + */ + +#define current_top_of_stack() \ +({ \ + unsigned long _low = 0; \ + unsigned long _high = 0; \ + \ + current_stack_type(current, current_stack_pointer, &_low, &_high); \ + _high; \ +}) +#define on_thread_stack() (on_task_stack(current, current_stack_pointer, NULL, NULL)) + #endif /* __ASSEMBLY__ */ #endif /* __ASM_PROCESSOR_H */ diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 28ad8799406f..67d12016063d 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -431,6 +431,11 @@ tsk .req x28 // current thread_info .text + .macro stackleak_erase +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK + bl stackleak_erase +#endif + .endm /* * Exception vectors. */ @@ -910,6 +915,7 @@ ret_fast_syscall: and x2, x1, #_TIF_WORK_MASK cbnz x2, work_pending enable_step_tsk x1, x2 + stackleak_erase kernel_exit 0 ret_fast_syscall_trace: enable_daif @@ -936,6 +942,7 @@ ret_to_user: cbnz x2, work_pending finish_ret_to_user: enable_step_tsk x1, x2 + stackleak_erase kernel_exit 0 ENDPROC(ret_to_user) diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index e10bc363f533..904defa36689 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -493,3 +493,35 @@ void arch_setup_new_exec(void) { current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0; } + +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK +void __used stackleak_check_alloca(unsigned long size) +{ + unsigned long stack_left; + enum stack_type type; + unsigned long current_sp = current_stack_pointer; + unsigned long low, high; + + type = current_stack_type(current, current_sp, &low, &high); + BUG_ON(type == STACK_TYPE_UNKNOWN); + + stack_left = current_sp - low; + + if (size >= stack_left) { + /* + * Kernel stack depth overflow is detected, let's report that. + * If CONFIG_VMAP_STACK is enabled, we can safely use BUG(). + * If CONFIG_VMAP_STACK is disabled, BUG() handling can corrupt + * the neighbour memory. CONFIG_SCHED_STACK_END_CHECK calls + * panic() in a similar situation, so let's do the same if that + * option is on. Otherwise just use BUG() and hope for the best. + */ +#if !defined(CONFIG_VMAP_STACK) && defined(CONFIG_SCHED_STACK_END_CHECK) + panic("alloca() over the kernel stack boundary\n"); +#else + BUG(); +#endif + } +} +EXPORT_SYMBOL(stackleak_check_alloca); +#endif diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile index 4313f7475333..2fabc2dc1966 100644 --- a/arch/arm64/kvm/hyp/Makefile +++ b/arch/arm64/kvm/hyp/Makefile @@ -3,7 +3,8 @@ # Makefile for Kernel-based Virtual Machine module, HYP part # -ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING +ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING \ + $(DISABLE_STACKLEAK_PLUGIN) KVM=../../../../virt/kvm diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index a34e9290a699..25dd2a14560d 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -20,7 +20,8 @@ cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \ -D__NO_FORTIFY \ $(call cc-option,-ffreestanding) \ - $(call cc-option,-fno-stack-protector) + $(call cc-option,-fno-stack-protector) \ + $(DISABLE_STACKLEAK_PLUGIN) GCOV_PROFILE := n KASAN_SANITIZE := n diff --git a/include/linux/stackleak.h b/include/linux/stackleak.h index b911b973d328..08420ec6b7c3 100644 --- a/include/linux/stackleak.h +++ b/include/linux/stackleak.h @@ -5,6 +5,7 @@ #include <linux/sched.h> #include <linux/sched/task_stack.h> +#include <asm/stacktrace.h> /* * Check that the poison value points to the unused hole in the * virtual memory map for your platform.
Implementation of stackleak based heavily on the x86 version Signed-off-by: Laura Abbott <labbott@redhat.com> --- Since last time: Minor style cleanups. Re-wrote check_alloca to correctly handle all stack types. While doing that, I also realized current_top_of_stack was incorrect so I fixed that as well. --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/processor.h | 17 ++++++++++++++ arch/arm64/kernel/entry.S | 7 ++++++ arch/arm64/kernel/process.c | 32 +++++++++++++++++++++++++++ arch/arm64/kvm/hyp/Makefile | 3 ++- drivers/firmware/efi/libstub/Makefile | 3 ++- include/linux/stackleak.h | 1 + 7 files changed, 62 insertions(+), 2 deletions(-)