tools/include/nolibc/stackprotector.h

   1 /* SPDX-License-Identifier: LGPL-2.1 OR MIT */
   2 /*
   3  * Stack protector support for NOLIBC
   4  * Copyright (C) 2023 Thomas Weißschuh <linux@weissschuh.net>
   5  */
   6
   7 #ifndef _NOLIBC_STACKPROTECTOR_H
   8 #define _NOLIBC_STACKPROTECTOR_H
   9
  10 #include "compiler.h"
  11
  12 #if defined(_NOLIBC_STACKPROTECTOR)
  13
  14 #include "sys.h"
  15 #include "stdlib.h"
  16
  17 /* The functions in this header are using raw syscall macros to avoid
  18  * triggering stack protector errors themselves
  19  */
  20
  21 __attribute__((weak,used,noreturn,section(".text.nolibc_stack_chk")))
  22 void __stack_chk_fail(void)
  23 {
  24         pid_t pid;
  25         my_syscall3(__NR_write, STDERR_FILENO, "!!Stack smashing detected!!\n", 28);
  26         pid = my_syscall0(__NR_getpid);
  27         my_syscall2(__NR_kill, pid, SIGABRT);
  28         for (;;);
  29 }
  30
  31 __attribute__((weak,noreturn,section(".text.nolibc_stack_chk")))
  32 void __stack_chk_fail_local(void)
  33 {
  34         __stack_chk_fail();
  35 }
  36
  37 __attribute__((weak,used,section(".data.nolibc_stack_chk")))
  38 uintptr_t __stack_chk_guard;
  39
  40 static __no_stack_protector void __stack_chk_init(void)
  41 {
  42         my_syscall3(__NR_getrandom, &__stack_chk_guard, sizeof(__stack_chk_guard), 0);
  43         /* a bit more randomness in case getrandom() fails, ensure the guard is never 0 */
  44         if (__stack_chk_guard != (uintptr_t) &__stack_chk_guard)
  45                 __stack_chk_guard ^= (uintptr_t) &__stack_chk_guard;
  46 }
  47 #else /* !defined(_NOLIBC_STACKPROTECTOR) */
  48 static void __stack_chk_init(void) {}
  49 #endif /* defined(_NOLIBC_STACKPROTECTOR) */
  50
  51 #endif /* _NOLIBC_STACKPROTECTOR_H */