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