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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
21void __stack_chk_fail(void);
22__attribute__((weak,used,noreturn,section(".text.nolibc_stack_chk")))
23void __stack_chk_fail(void)
24{
25 pid_t pid;
26 my_syscall3(__NR_write, STDERR_FILENO, "!!Stack smashing detected!!\n", 28);
27 pid = my_syscall0(__NR_getpid);
28 my_syscall2(__NR_kill, pid, SIGABRT);
29 for (;;);
30}
31
32void __stack_chk_fail_local(void);
33__attribute__((weak,noreturn,section(".text.nolibc_stack_chk")))
34void __stack_chk_fail_local(void)
35{
36 __stack_chk_fail();
37}
38
39__attribute__((weak,used,section(".data.nolibc_stack_chk")))
40uintptr_t __stack_chk_guard;
41
42static __no_stack_protector void __stack_chk_init(void)
43{
44 my_syscall3(__NR_getrandom, &__stack_chk_guard, sizeof(__stack_chk_guard), 0);
45 /* a bit more randomness in case getrandom() fails, ensure the guard is never 0 */
46 if (__stack_chk_guard != (uintptr_t) &__stack_chk_guard)
47 __stack_chk_guard ^= (uintptr_t) &__stack_chk_guard;
48}
49#else /* !defined(_NOLIBC_STACKPROTECTOR) */
50static void __stack_chk_init(void) {}
51#endif /* defined(_NOLIBC_STACKPROTECTOR) */
52
53#endif /* _NOLIBC_STACKPROTECTOR_H */