Linux kernel mirror (for testing)
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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);
22extern void add_bootloader_randomness(const void *, unsigned int);
23
24#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
25static inline void add_latent_entropy(void)
26{
27 add_device_randomness((const void *)&latent_entropy,
28 sizeof(latent_entropy));
29}
30#else
31static inline void add_latent_entropy(void) {}
32#endif
33
34extern void add_input_randomness(unsigned int type, unsigned int code,
35 unsigned int value) __latent_entropy;
36extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;
37
38extern void get_random_bytes(void *buf, int nbytes);
39extern int wait_for_random_bytes(void);
40extern int __init rand_initialize(void);
41extern bool rng_is_initialized(void);
42extern int add_random_ready_callback(struct random_ready_callback *rdy);
43extern void del_random_ready_callback(struct random_ready_callback *rdy);
44extern int __must_check get_random_bytes_arch(void *buf, int nbytes);
45
46#ifndef MODULE
47extern const struct file_operations random_fops, urandom_fops;
48#endif
49
50u32 get_random_u32(void);
51u64 get_random_u64(void);
52static inline unsigned int get_random_int(void)
53{
54 return get_random_u32();
55}
56static inline unsigned long get_random_long(void)
57{
58#if BITS_PER_LONG == 64
59 return get_random_u64();
60#else
61 return get_random_u32();
62#endif
63}
64
65/*
66 * On 64-bit architectures, protect against non-terminated C string overflows
67 * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
68 */
69#ifdef CONFIG_64BIT
70# ifdef __LITTLE_ENDIAN
71# define CANARY_MASK 0xffffffffffffff00UL
72# else /* big endian, 64 bits: */
73# define CANARY_MASK 0x00ffffffffffffffUL
74# endif
75#else /* 32 bits: */
76# define CANARY_MASK 0xffffffffUL
77#endif
78
79static inline unsigned long get_random_canary(void)
80{
81 unsigned long val = get_random_long();
82
83 return val & CANARY_MASK;
84}
85
86/* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
87 * Returns the result of the call to wait_for_random_bytes. */
88static inline int get_random_bytes_wait(void *buf, int nbytes)
89{
90 int ret = wait_for_random_bytes();
91 get_random_bytes(buf, nbytes);
92 return ret;
93}
94
95#define declare_get_random_var_wait(var) \
96 static inline int get_random_ ## var ## _wait(var *out) { \
97 int ret = wait_for_random_bytes(); \
98 if (unlikely(ret)) \
99 return ret; \
100 *out = get_random_ ## var(); \
101 return 0; \
102 }
103declare_get_random_var_wait(u32)
104declare_get_random_var_wait(u64)
105declare_get_random_var_wait(int)
106declare_get_random_var_wait(long)
107#undef declare_get_random_var
108
109unsigned long randomize_page(unsigned long start, unsigned long range);
110
111u32 prandom_u32(void);
112void prandom_bytes(void *buf, size_t nbytes);
113void prandom_seed(u32 seed);
114void prandom_reseed_late(void);
115
116struct rnd_state {
117 __u32 s1, s2, s3, s4;
118};
119
120u32 prandom_u32_state(struct rnd_state *state);
121void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
122void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
123
124#define prandom_init_once(pcpu_state) \
125 DO_ONCE(prandom_seed_full_state, (pcpu_state))
126
127/**
128 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
129 * @ep_ro: right open interval endpoint
130 *
131 * Returns a pseudo-random number that is in interval [0, ep_ro). Note
132 * that the result depends on PRNG being well distributed in [0, ~0U]
133 * u32 space. Here we use maximally equidistributed combined Tausworthe
134 * generator, that is, prandom_u32(). This is useful when requesting a
135 * random index of an array containing ep_ro elements, for example.
136 *
137 * Returns: pseudo-random number in interval [0, ep_ro)
138 */
139static inline u32 prandom_u32_max(u32 ep_ro)
140{
141 return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
142}
143
144/*
145 * Handle minimum values for seeds
146 */
147static inline u32 __seed(u32 x, u32 m)
148{
149 return (x < m) ? x + m : x;
150}
151
152/**
153 * prandom_seed_state - set seed for prandom_u32_state().
154 * @state: pointer to state structure to receive the seed.
155 * @seed: arbitrary 64-bit value to use as a seed.
156 */
157static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
158{
159 u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
160
161 state->s1 = __seed(i, 2U);
162 state->s2 = __seed(i, 8U);
163 state->s3 = __seed(i, 16U);
164 state->s4 = __seed(i, 128U);
165}
166
167#ifdef CONFIG_ARCH_RANDOM
168# include <asm/archrandom.h>
169#else
170static inline bool arch_get_random_long(unsigned long *v)
171{
172 return 0;
173}
174static inline bool arch_get_random_int(unsigned int *v)
175{
176 return 0;
177}
178static inline bool arch_has_random(void)
179{
180 return 0;
181}
182static inline bool arch_get_random_seed_long(unsigned long *v)
183{
184 return 0;
185}
186static inline bool arch_get_random_seed_int(unsigned int *v)
187{
188 return 0;
189}
190static inline bool arch_has_random_seed(void)
191{
192 return 0;
193}
194#endif
195
196/* Pseudo random number generator from numerical recipes. */
197static inline u32 next_pseudo_random32(u32 seed)
198{
199 return seed * 1664525 + 1013904223;
200}
201
202#endif /* _LINUX_RANDOM_H */