LXR linux/arch/arm64/include/asm/stackprotector.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * GCC stack protector support.
   4 *
   5 * Stack protector works by putting predefined pattern at the start of
   6 * the stack frame and verifying that it hasn't been overwritten when
   7 * returning from the function.  The pattern is called stack canary
   8 * and gcc expects it to be defined by a global variable called
   9 * "__stack_chk_guard" on ARM.  This unfortunately means that on SMP
  10 * we cannot have a different canary value per task.
  11 */
  12
  13#ifndef __ASM_STACKPROTECTOR_H
  14#define __ASM_STACKPROTECTOR_H
  15
  16#include <linux/random.h>
  17#include <linux/version.h>
  18#include <asm/pointer_auth.h>
  19
  20extern unsigned long __stack_chk_guard;
  21
  22/*
  23 * Initialize the stackprotector canary value.
  24 *
  25 * NOTE: this must only be called from functions that never return,
  26 * and it must always be inlined.
  27 */
  28static __always_inline void boot_init_stack_canary(void)
  29{
  30#if defined(CONFIG_STACKPROTECTOR)
  31        unsigned long canary;
  32
  33        /* Try to get a semi random initial value. */
  34        get_random_bytes(&canary, sizeof(canary));
  35        canary ^= LINUX_VERSION_CODE;
  36        canary &= CANARY_MASK;
  37
  38        current->stack_canary = canary;
  39        if (!IS_ENABLED(CONFIG_STACKPROTECTOR_PER_TASK))
  40                __stack_chk_guard = current->stack_canary;
  41#endif
  42        ptrauth_thread_init_kernel(current);
  43        ptrauth_thread_switch_kernel(current);
  44        ptrauth_enable();
  45}
  46
  47#endif  /* _ASM_STACKPROTECTOR_H */
  48