Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * include/linux/random.h
4 *
5 * Include file for the random number generator.
6 */
7#ifndef _LINUX_RANDOM_H
8#define _LINUX_RANDOM_H
9
10#include <linux/list.h>
11#include <linux/once.h>
12
13#include <uapi/linux/random.h>
14
15struct random_ready_callback {
16 struct list_head list;
17 void (*func)(struct random_ready_callback *rdy);
18 struct module *owner;
19};
20
21extern void add_device_randomness(const void *, unsigned int);
22
23#if defined(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) && !defined(__CHECKER__)
24static inline void add_latent_entropy(void)
25{
26 add_device_randomness((const void *)&latent_entropy,
27 sizeof(latent_entropy));
28}
29#else
30static inline void add_latent_entropy(void) {}
31#endif
32
33extern void add_input_randomness(unsigned int type, unsigned int code,
34 unsigned int value) __latent_entropy;
35extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;
36
37extern void get_random_bytes(void *buf, int nbytes);
38extern int wait_for_random_bytes(void);
39extern int add_random_ready_callback(struct random_ready_callback *rdy);
40extern void del_random_ready_callback(struct random_ready_callback *rdy);
41extern void get_random_bytes_arch(void *buf, int nbytes);
42
43#ifndef MODULE
44extern const struct file_operations random_fops, urandom_fops;
45#endif
46
47u32 get_random_u32(void);
48u64 get_random_u64(void);
49static inline unsigned int get_random_int(void)
50{
51 return get_random_u32();
52}
53static inline unsigned long get_random_long(void)
54{
55#if BITS_PER_LONG == 64
56 return get_random_u64();
57#else
58 return get_random_u32();
59#endif
60}
61
62/*
63 * On 64-bit architectures, protect against non-terminated C string overflows
64 * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
65 */
66#ifdef CONFIG_64BIT
67# ifdef __LITTLE_ENDIAN
68# define CANARY_MASK 0xffffffffffffff00UL
69# else /* big endian, 64 bits: */
70# define CANARY_MASK 0x00ffffffffffffffUL
71# endif
72#else /* 32 bits: */
73# define CANARY_MASK 0xffffffffUL
74#endif
75
76static inline unsigned long get_random_canary(void)
77{
78 unsigned long val = get_random_long();
79
80 return val & CANARY_MASK;
81}
82
83/* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
84 * Returns the result of the call to wait_for_random_bytes. */
85static inline int get_random_bytes_wait(void *buf, int nbytes)
86{
87 int ret = wait_for_random_bytes();
88 get_random_bytes(buf, nbytes);
89 return ret;
90}
91
92#define declare_get_random_var_wait(var) \
93 static inline int get_random_ ## var ## _wait(var *out) { \
94 int ret = wait_for_random_bytes(); \
95 if (unlikely(ret)) \
96 return ret; \
97 *out = get_random_ ## var(); \
98 return 0; \
99 }
100declare_get_random_var_wait(u32)
101declare_get_random_var_wait(u64)
102declare_get_random_var_wait(int)
103declare_get_random_var_wait(long)
104#undef declare_get_random_var
105
106unsigned long randomize_page(unsigned long start, unsigned long range);
107
108u32 prandom_u32(void);
109void prandom_bytes(void *buf, size_t nbytes);
110void prandom_seed(u32 seed);
111void prandom_reseed_late(void);
112
113struct rnd_state {
114 __u32 s1, s2, s3, s4;
115};
116
117u32 prandom_u32_state(struct rnd_state *state);
118void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
119void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
120
121#define prandom_init_once(pcpu_state) \
122 DO_ONCE(prandom_seed_full_state, (pcpu_state))
123
124/**
125 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
126 * @ep_ro: right open interval endpoint
127 *
128 * Returns a pseudo-random number that is in interval [0, ep_ro). Note
129 * that the result depends on PRNG being well distributed in [0, ~0U]
130 * u32 space. Here we use maximally equidistributed combined Tausworthe
131 * generator, that is, prandom_u32(). This is useful when requesting a
132 * random index of an array containing ep_ro elements, for example.
133 *
134 * Returns: pseudo-random number in interval [0, ep_ro)
135 */
136static inline u32 prandom_u32_max(u32 ep_ro)
137{
138 return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
139}
140
141/*
142 * Handle minimum values for seeds
143 */
144static inline u32 __seed(u32 x, u32 m)
145{
146 return (x < m) ? x + m : x;
147}
148
149/**
150 * prandom_seed_state - set seed for prandom_u32_state().
151 * @state: pointer to state structure to receive the seed.
152 * @seed: arbitrary 64-bit value to use as a seed.
153 */
154static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
155{
156 u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
157
158 state->s1 = __seed(i, 2U);
159 state->s2 = __seed(i, 8U);
160 state->s3 = __seed(i, 16U);
161 state->s4 = __seed(i, 128U);
162}
163
164#ifdef CONFIG_ARCH_RANDOM
165# include <asm/archrandom.h>
166#else
167static inline bool arch_get_random_long(unsigned long *v)
168{
169 return 0;
170}
171static inline bool arch_get_random_int(unsigned int *v)
172{
173 return 0;
174}
175static inline bool arch_has_random(void)
176{
177 return 0;
178}
179static inline bool arch_get_random_seed_long(unsigned long *v)
180{
181 return 0;
182}
183static inline bool arch_get_random_seed_int(unsigned int *v)
184{
185 return 0;
186}
187static inline bool arch_has_random_seed(void)
188{
189 return 0;
190}
191#endif
192
193/* Pseudo random number generator from numerical recipes. */
194static inline u32 next_pseudo_random32(u32 seed)
195{
196 return seed * 1664525 + 1013904223;
197}
198
199#endif /* _LINUX_RANDOM_H */