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 #ifndef NOLIBC_NO_RUNTIME
13 #if defined(_NOLIBC_STACKPROTECTOR)
14
15 #include "sys.h"
16 #include "stdlib.h"
17
18 /* The functions in this header are using raw syscall macros to avoid
19 * triggering stack protector errors themselves
20 */
21
22 void __stack_chk_fail(void);
23 __attribute__((weak,used,noreturn,section(".text.nolibc_stack_chk")))
__stack_chk_fail(void)24 void __stack_chk_fail(void)
25 {
26 pid_t pid;
27 my_syscall3(__NR_write, STDERR_FILENO, "!!Stack smashing detected!!\n", 28);
28 pid = my_syscall0(__NR_getpid);
29 my_syscall2(__NR_kill, pid, SIGABRT);
30 for (;;);
31 }
32
33 void __stack_chk_fail_local(void);
34 __attribute__((weak,noreturn,section(".text.nolibc_stack_chk")))
__stack_chk_fail_local(void)35 void __stack_chk_fail_local(void)
36 {
37 __stack_chk_fail();
38 }
39
40 __attribute__((weak,used,section(".data.nolibc_stack_chk")))
41 uintptr_t __stack_chk_guard;
42
__stack_chk_init(void)43 static __no_stack_protector void __stack_chk_init(void)
44 {
45 my_syscall3(__NR_getrandom, &__stack_chk_guard, sizeof(__stack_chk_guard), 0);
46 /* a bit more randomness in case getrandom() fails, ensure the guard is never 0 */
47 if (__stack_chk_guard != (uintptr_t) &__stack_chk_guard)
48 __stack_chk_guard ^= (uintptr_t) &__stack_chk_guard;
49 }
50 #else /* !defined(_NOLIBC_STACKPROTECTOR) */
__stack_chk_init(void)51 static void __stack_chk_init(void) {}
52 #endif /* defined(_NOLIBC_STACKPROTECTOR) */
53 #endif /* NOLIBC_NO_RUNTIME */
54
55 #endif /* _NOLIBC_STACKPROTECTOR_H */
56