| Message ID | 20180712000337.GA4022@beast (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 07/11/2018 05:03 PM, Kees Cook wrote: > From: Laura Abbott <labbott@redhat.com> > > This adds support for the STACKLEAK gcc plugin to arm64 by implementing > stackleak_check_alloca(), based heavily on the x86 version, and adding the > two helpers used by the stackleak common code: current_top_of_stack() and > on_thread_stack(). The stack erasure calls are made at syscall returns. > Additionally, this disables the plugin in hypervisor and EFI stub code, > which are out of scope for the protection. > > Signed-off-by: Laura Abbott <labbott@redhat.com> > [kees: add cast to current_top_of_stack(), tweak commit log & comments] > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > This is tweaked to be stand-alone from Alexander's series so it can land > via the arm64 tree. (Alexander's v14 pulled one change out already, and > I've lifted the last remaining: the newly needed include in stackleak.h) > --- > arch/arm64/Kconfig | 1 + > arch/arm64/include/asm/processor.h | 10 ++++++++++ > arch/arm64/kernel/entry.S | 7 +++++++ > arch/arm64/kernel/process.c | 16 ++++++++++++++++ > arch/arm64/kvm/hyp/Makefile | 3 ++- > drivers/firmware/efi/libstub/Makefile | 3 ++- > 6 files changed, 38 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..ca856bda2051 100644 > --- a/arch/arm64/include/asm/processor.h > +++ b/arch/arm64/include/asm/processor.h > @@ -266,5 +266,15 @@ 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 the STACKLEAK gcc plugin. > + * > + * 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)task_stack_page(current) + \ > + THREAD_SIZE) > +#define on_thread_stack() (on_task_stack(current, current_stack_pointer)) > + > #endif /* __ASSEMBLY__ */ > #endif /* __ASM_PROCESSOR_H */ > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index 28ad8799406f..80bc93d971f7 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_kstack > +#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..d99281b476b0 100644 > --- a/arch/arm64/kernel/process.c > +++ b/arch/arm64/kernel/process.c > @@ -493,3 +493,19 @@ void arch_setup_new_exec(void) > { > current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0; > } > + > +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK > +#define MIN_STACK_LEFT 256 > + > +void __used stackleak_check_alloca(unsigned long size) > +{ > + unsigned long sp, stack_left; > + > + sp = current_stack_pointer; > + > + stack_left = sp & (THREAD_SIZE - 1); > + BUG_ON(stack_left < MIN_STACK_LEFT || > + size >= stack_left - MIN_STACK_LEFT); > +} > +EXPORT_SYMBOL(stackleak_check_alloca); > +#endif I think the conclusion was this needs to be re-written to account for the different stack sizes in the same way as x86. > 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 >
On Wed, Jul 11, 2018 at 6:45 PM, Laura Abbott <labbott@redhat.com> wrote: >> +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK >> +#define MIN_STACK_LEFT 256 >> + >> +void __used stackleak_check_alloca(unsigned long size) >> +{ >> + unsigned long sp, stack_left; >> + >> + sp = current_stack_pointer; >> + >> + stack_left = sp & (THREAD_SIZE - 1); >> + BUG_ON(stack_left < MIN_STACK_LEFT || >> + size >= stack_left - MIN_STACK_LEFT); >> +} >> +EXPORT_SYMBOL(stackleak_check_alloca); >> +#endif > > > I think the conclusion was this needs to be re-written to account > for the different stack sizes in the same way as x86. Oh, whoops! Sorry, I missed that fork of the thread. :) -Kees
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..ca856bda2051 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -266,5 +266,15 @@ 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 the STACKLEAK gcc plugin. + * + * 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)task_stack_page(current) + \ + THREAD_SIZE) +#define on_thread_stack() (on_task_stack(current, current_stack_pointer)) + #endif /* __ASSEMBLY__ */ #endif /* __ASM_PROCESSOR_H */ diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 28ad8799406f..80bc93d971f7 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_kstack +#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..d99281b476b0 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -493,3 +493,19 @@ void arch_setup_new_exec(void) { current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0; } + +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK +#define MIN_STACK_LEFT 256 + +void __used stackleak_check_alloca(unsigned long size) +{ + unsigned long sp, stack_left; + + sp = current_stack_pointer; + + stack_left = sp & (THREAD_SIZE - 1); + BUG_ON(stack_left < MIN_STACK_LEFT || + size >= stack_left - MIN_STACK_LEFT); +} +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