Commit c6f1b355 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'gcc-plugins-v4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux 

Pull gcc-plugins update from Kees Cook:
 "Both arm and arm64 are gaining per-task stack canaries (to match x86),
  but arm is being done with a gcc plugin, hence it going through the
  gcc-plugins tree.

  New gcc-plugin:

   - Enable per-task stack protector for ARM (Ard Biesheuvel)"

* tag 'gcc-plugins-v4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  ARM: smp: add support for per-task stack canaries
parents c06e9ef6 189af465

arch/arm/Kconfig

+15 −0
Original line number Diff line number Diff line
@@ -1810,6 +1810,21 @@ config XEN 
	help

	  Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.



config STACKPROTECTOR_PER_TASK

	bool "Use a unique stack canary value for each task"

	depends on GCC_PLUGINS && STACKPROTECTOR && SMP && !XIP_DEFLATED_DATA

	select GCC_PLUGIN_ARM_SSP_PER_TASK

	default y

	help

	  Due to the fact that GCC uses an ordinary symbol reference from

	  which to load the value of the stack canary, this value can only

	  change at reboot time on SMP systems, and all tasks running in the

	  kernel's address space are forced to use the same canary value for

	  the entire duration that the system is up.



	  Enable this option to switch to a different method that uses a

	  different canary value for each task.



endmenu



menu "Boot options"

arch/arm/Makefile

+12 −0
Original line number Diff line number Diff line
@@ -303,6 +303,18 @@ else 
KBUILD_IMAGE := $(boot)/zImage

endif



ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)

prepare: stack_protector_prepare

stack_protector_prepare: prepare0

	$(eval KBUILD_CFLAGS += \

		-fplugin-arg-arm_ssp_per_task_plugin-tso=$(shell	\

			awk '{if ($$2 == "THREAD_SZ_ORDER") print $$3;}'\

				include/generated/asm-offsets.h)	\

		-fplugin-arg-arm_ssp_per_task_plugin-offset=$(shell	\

			awk '{if ($$2 == "TI_STACK_CANARY") print $$3;}'\

				include/generated/asm-offsets.h))

endif



all:	$(notdir $(KBUILD_IMAGE))

arch/arm/boot/compressed/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -101,6 +101,7 @@ clean-files += piggy_data lib1funcs.S ashldi3.S bswapsdi2.S \ 
		$(libfdt) $(libfdt_hdrs) hyp-stub.S



KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING

KBUILD_CFLAGS += $(DISABLE_ARM_SSP_PER_TASK_PLUGIN)



ifeq ($(CONFIG_FUNCTION_TRACER),y)

ORIG_CFLAGS := $(KBUILD_CFLAGS)

arch/arm/include/asm/stackprotector.h

+10 −2
Original line number Diff line number Diff line
@@ -6,8 +6,10 @@ 
 * the stack frame and verifying that it hasn't been overwritten when

 * returning from the function.  The pattern is called stack canary

 * and gcc expects it to be defined by a global variable called

 * "__stack_chk_guard" on ARM.  This unfortunately means that on SMP

 * we cannot have a different canary value per task.

 * "__stack_chk_guard" on ARM.  This prevents SMP systems from using a

 * different value for each task unless we enable a GCC plugin that

 * replaces these symbol references with references to each task's own

 * value.

 */



#ifndef _ASM_STACKPROTECTOR_H
@@ -16,6 +18,8 @@ 
#include <linux/random.h>

#include <linux/version.h>



#include <asm/thread_info.h>



extern unsigned long __stack_chk_guard;



/*
@@ -33,7 +37,11 @@ static __always_inline void boot_init_stack_canary(void) 
	canary ^= LINUX_VERSION_CODE;



	current->stack_canary = canary;

#ifndef CONFIG_STACKPROTECTOR_PER_TASK

	__stack_chk_guard = current->stack_canary;

#else

	current_thread_info()->stack_canary = current->stack_canary;

#endif

}



#endif	/* _ASM_STACKPROTECTOR_H */

arch/arm/include/asm/thread_info.h

+3 −0
Original line number Diff line number Diff line
@@ -53,6 +53,9 @@ struct thread_info { 
	struct task_struct	*task;		/* main task structure */

	__u32			cpu;		/* cpu */

	__u32			cpu_domain;	/* cpu domain */

#ifdef CONFIG_STACKPROTECTOR_PER_TASK

	unsigned long		stack_canary;

#endif

	struct cpu_context_save	cpu_context;	/* cpu context */

	__u32			syscall;	/* syscall number */

	__u8			used_cp[16];	/* thread used copro */