Commit a45728fd authored by Youling Tang's avatar Youling Tang Committed by Huacai Chen
Browse files

LoongArch: Enable HAVE_ARCH_STACKLEAK 



Add support for the stackleak feature. It initializes the stack with the
poison value before returning from system calls which improves the kernel
security.

At the same time, disables the plugin in EFI stub code because EFI stub
is out of scope for the protection.

Tested on Loongson-3A5000 (enable GCC_PLUGIN_STACKLEAK and LKDTM):
 # echo STACKLEAK_ERASING > /sys/kernel/debug/provoke-crash/DIRECT
 # dmesg
   lkdtm: Performing direct entry STACKLEAK_ERASING
   lkdtm: stackleak stack usage:
      high offset: 320 bytes
      current:     448 bytes
      lowest:      1264 bytes
      tracked:     1264 bytes
      untracked:   208 bytes
      poisoned:    14528 bytes
      low offset:  64 bytes
   lkdtm: OK: the rest of the thread stack is properly erased

Signed-off-by: default avatarYouling Tang <tangyouling@kylinos.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent b37981ce

arch/loongarch/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -124,6 +124,7 @@ config LOONGARCH 
	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET

	select HAVE_ARCH_SECCOMP

	select HAVE_ARCH_SECCOMP_FILTER

	select HAVE_ARCH_STACKLEAK

	select HAVE_ARCH_TRACEHOOK

	select HAVE_ARCH_TRANSPARENT_HUGEPAGE

	select HAVE_ARCH_USERFAULTFD_MINOR if USERFAULTFD

arch/loongarch/include/asm/entry-common.h

+1 −7
Original line number Diff line number Diff line
@@ -2,12 +2,6 @@ 
#ifndef ARCH_LOONGARCH_ENTRY_COMMON_H

#define ARCH_LOONGARCH_ENTRY_COMMON_H



#include <linux/sched.h>

#include <linux/processor.h>



static inline bool on_thread_stack(void)

{

	return !(((unsigned long)(current->stack) ^ current_stack_pointer) & ~(THREAD_SIZE - 1));

}

#include <asm/stacktrace.h> /* For on_thread_stack() */



#endif

arch/loongarch/include/asm/stackframe.h

+6 −0
Original line number Diff line number Diff line
@@ -57,6 +57,12 @@ 
	jirl	zero, \temp1, 0xc

	.endm



	.macro STACKLEAK_ERASE

#ifdef CONFIG_GCC_PLUGIN_STACKLEAK

	bl	stackleak_erase_on_task_stack

#endif

	.endm



	.macro BACKUP_T0T1

	csrwr	t0, EXCEPTION_KS0

	csrwr	t1, EXCEPTION_KS1

arch/loongarch/include/asm/stacktrace.h

+5 −0
Original line number Diff line number Diff line
@@ -31,6 +31,11 @@ bool in_irq_stack(unsigned long stack, struct stack_info *info); 
bool in_task_stack(unsigned long stack, struct task_struct *task, struct stack_info *info);

int get_stack_info(unsigned long stack, struct task_struct *task, struct stack_info *info);



static __always_inline bool on_thread_stack(void)

{

	return !(((unsigned long)(current->stack) ^ current_stack_pointer) & ~(THREAD_SIZE - 1));

}



#define STR_LONG_L    __stringify(LONG_L)

#define STR_LONG_S    __stringify(LONG_S)

#define STR_LONGSIZE  __stringify(LONGSIZE)

arch/loongarch/kernel/entry.S

+3 −0
Original line number Diff line number Diff line
@@ -73,6 +73,7 @@ SYM_CODE_START(handle_syscall) 
	move		a0, sp

	bl		do_syscall



	STACKLEAK_ERASE

	RESTORE_ALL_AND_RET

SYM_CODE_END(handle_syscall)

_ASM_NOKPROBE(handle_syscall)
@@ -81,6 +82,7 @@ SYM_CODE_START(ret_from_fork_asm) 
	UNWIND_HINT_REGS

	move		a1, sp

	bl 		ret_from_fork

	STACKLEAK_ERASE

	RESTORE_STATIC

	RESTORE_SOME

	RESTORE_SP_AND_RET
@@ -92,6 +94,7 @@ SYM_CODE_START(ret_from_kernel_thread_asm) 
	move		a2, s0

	move		a3, s1

	bl		ret_from_kernel_thread

	STACKLEAK_ERASE

	RESTORE_STATIC

	RESTORE_SOME

	RESTORE_SP_AND_RET