stackprotector.h

 1/* SPDX-License-Identifier: GPL-2.0 */
 2#ifndef _LINUX_STACKPROTECTOR_H
 3#define _LINUX_STACKPROTECTOR_H 1
 4
 5#include <linux/compiler.h>
 6#include <linux/sched.h>
 7#include <linux/random.h>
 8
 9/*
10 * On 64-bit architectures, protect against non-terminated C string overflows
11 * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
12 */
13#ifdef CONFIG_64BIT
14# ifdef __LITTLE_ENDIAN
15#  define CANARY_MASK 0xffffffffffffff00UL
16# else /* big endian, 64 bits: */
17#  define CANARY_MASK 0x00ffffffffffffffUL
18# endif
19#else /* 32 bits: */
20# define CANARY_MASK 0xffffffffUL
21#endif
22
23static inline unsigned long get_random_canary(void)
24{
25	return get_random_long() & CANARY_MASK;
26}
27
28#if defined(CONFIG_STACKPROTECTOR) || defined(CONFIG_ARM64_PTR_AUTH)
29# include <asm/stackprotector.h>
30#else
31static inline void boot_init_stack_canary(void)
32{
33}
34#endif
35
36#endif