1/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
2/*
3 * Stack protector support for NOLIBC
4 * Copyright (C) 2023 Thomas Wei��schuh <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,noreturn,section(".text.nolibc_stack_chk")))
22void __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")))
32void __stack_chk_fail_local(void)
33{
34	__stack_chk_fail();
35}
36
37__attribute__((weak,section(".data.nolibc_stack_chk")))
38uintptr_t __stack_chk_guard;
39
40static __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) */
48static void __stack_chk_init(void) {}
49#endif /* defined(_NOLIBC_STACKPROTECTOR) */
50
51#endif /* _NOLIBC_STACKPROTECTOR_H */
52