Commit 0b3e3366 authored by Laura Abbott's avatar Laura Abbott Committed by Will Deacon
Browse files

arm64: Add support for STACKLEAK gcc plugin 



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.

Acked-by: default avatarAlexander Popov <alex.popov@linux.com>
Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarLaura Abbott <labbott@redhat.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 8a1ccfbc

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -108,6 +108,7 @@ 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

arch/arm64/include/asm/processor.h

+15 −0
Original line number Diff line number Diff line
@@ -266,5 +266,20 @@ 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_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()							\

({										\

	struct stack_info _info;						\

	BUG_ON(!on_accessible_stack(current, current_stack_pointer, &_info));	\

	_info.high;								\

})

#define on_thread_stack()	(on_task_stack(current, current_stack_pointer, NULL))



#endif /* __ASSEMBLY__ */

#endif /* __ASM_PROCESSOR_H */

arch/arm64/kernel/entry.S

+3 −0
Original line number Diff line number Diff line
@@ -902,6 +902,9 @@ ret_to_user: 
	cbnz	x2, work_pending

finish_ret_to_user:

	enable_step_tsk x1, x2

#ifdef CONFIG_GCC_PLUGIN_STACKLEAK

	bl	stackleak_erase

#endif

	kernel_exit 0

ENDPROC(ret_to_user)

arch/arm64/kernel/process.c

+22 −0
Original line number Diff line number Diff line
@@ -493,3 +493,25 @@ 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;

	unsigned long current_sp = current_stack_pointer;

	struct stack_info info;



	BUG_ON(!on_accessible_stack(current, current_sp, &info));



	stack_left = current_sp - info.low;



	/*

	 * There's a good chance we're almost out of stack space if this

	 * is true. Using panic() over BUG() is more likely to give

	 * reliable debugging output.

	 */

	if (size >= stack_left)

		panic("alloca() over the kernel stack boundary\n");

}

EXPORT_SYMBOL(stackleak_check_alloca);

#endif

arch/arm64/kvm/hyp/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -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

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