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/bug.h>
11#include <linux/kernel.h>
12#include <linux/list.h>
13#include <linux/once.h>
14#include <asm/percpu.h>
15
16#include <uapi/linux/random.h>
17
18struct random_ready_callback {
19 struct list_head list;
20 void (*func)(struct random_ready_callback *rdy);
21 struct module *owner;
22};
23
24extern void add_device_randomness(const void *, unsigned int);
25extern void add_bootloader_randomness(const void *, unsigned int);
26
27#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
28static inline void add_latent_entropy(void)
29{
30 add_device_randomness((const void *)&latent_entropy,
31 sizeof(latent_entropy));
32}
33#else
34static inline void add_latent_entropy(void) {}
35#endif
36
37extern void add_input_randomness(unsigned int type, unsigned int code,
38 unsigned int value) __latent_entropy;
39extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;
40
41extern void get_random_bytes(void *buf, int nbytes);
42extern int wait_for_random_bytes(void);
43extern int __init rand_initialize(void);
44extern bool rng_is_initialized(void);
45extern int add_random_ready_callback(struct random_ready_callback *rdy);
46extern void del_random_ready_callback(struct random_ready_callback *rdy);
47extern int __must_check get_random_bytes_arch(void *buf, int nbytes);
48
49#ifndef MODULE
50extern const struct file_operations random_fops, urandom_fops;
51#endif
52
53u32 get_random_u32(void);
54u64 get_random_u64(void);
55static inline unsigned int get_random_int(void)
56{
57 return get_random_u32();
58}
59static inline unsigned long get_random_long(void)
60{
61#if BITS_PER_LONG == 64
62 return get_random_u64();
63#else
64 return get_random_u32();
65#endif
66}
67
68/*
69 * On 64-bit architectures, protect against non-terminated C string overflows
70 * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
71 */
72#ifdef CONFIG_64BIT
73# ifdef __LITTLE_ENDIAN
74# define CANARY_MASK 0xffffffffffffff00UL
75# else /* big endian, 64 bits: */
76# define CANARY_MASK 0x00ffffffffffffffUL
77# endif
78#else /* 32 bits: */
79# define CANARY_MASK 0xffffffffUL
80#endif
81
82static inline unsigned long get_random_canary(void)
83{
84 unsigned long val = get_random_long();
85
86 return val & CANARY_MASK;
87}
88
89/* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
90 * Returns the result of the call to wait_for_random_bytes. */
91static inline int get_random_bytes_wait(void *buf, int nbytes)
92{
93 int ret = wait_for_random_bytes();
94 get_random_bytes(buf, nbytes);
95 return ret;
96}
97
98#define declare_get_random_var_wait(var) \
99 static inline int get_random_ ## var ## _wait(var *out) { \
100 int ret = wait_for_random_bytes(); \
101 if (unlikely(ret)) \
102 return ret; \
103 *out = get_random_ ## var(); \
104 return 0; \
105 }
106declare_get_random_var_wait(u32)
107declare_get_random_var_wait(u64)
108declare_get_random_var_wait(int)
109declare_get_random_var_wait(long)
110#undef declare_get_random_var
111
112unsigned long randomize_page(unsigned long start, unsigned long range);
113
114u32 prandom_u32(void);
115void prandom_bytes(void *buf, size_t nbytes);
116void prandom_seed(u32 seed);
117void prandom_reseed_late(void);
118
119struct rnd_state {
120 __u32 s1, s2, s3, s4;
121};
122
123DECLARE_PER_CPU(struct rnd_state, net_rand_state);
124
125u32 prandom_u32_state(struct rnd_state *state);
126void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
127void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
128
129#define prandom_init_once(pcpu_state) \
130 DO_ONCE(prandom_seed_full_state, (pcpu_state))
131
132/**
133 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
134 * @ep_ro: right open interval endpoint
135 *
136 * Returns a pseudo-random number that is in interval [0, ep_ro). Note
137 * that the result depends on PRNG being well distributed in [0, ~0U]
138 * u32 space. Here we use maximally equidistributed combined Tausworthe
139 * generator, that is, prandom_u32(). This is useful when requesting a
140 * random index of an array containing ep_ro elements, for example.
141 *
142 * Returns: pseudo-random number in interval [0, ep_ro)
143 */
144static inline u32 prandom_u32_max(u32 ep_ro)
145{
146 return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
147}
148
149/*
150 * Handle minimum values for seeds
151 */
152static inline u32 __seed(u32 x, u32 m)
153{
154 return (x < m) ? x + m : x;
155}
156
157/**
158 * prandom_seed_state - set seed for prandom_u32_state().
159 * @state: pointer to state structure to receive the seed.
160 * @seed: arbitrary 64-bit value to use as a seed.
161 */
162static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
163{
164 u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
165
166 state->s1 = __seed(i, 2U);
167 state->s2 = __seed(i, 8U);
168 state->s3 = __seed(i, 16U);
169 state->s4 = __seed(i, 128U);
170}
171
172#ifdef CONFIG_ARCH_RANDOM
173# include <asm/archrandom.h>
174#else
175static inline bool __must_check arch_get_random_long(unsigned long *v)
176{
177 return false;
178}
179static inline bool __must_check arch_get_random_int(unsigned int *v)
180{
181 return false;
182}
183static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
184{
185 return false;
186}
187static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
188{
189 return false;
190}
191#endif
192
193/*
194 * Called from the boot CPU during startup; not valid to call once
195 * secondary CPUs are up and preemption is possible.
196 */
197#ifndef arch_get_random_seed_long_early
198static inline bool __init arch_get_random_seed_long_early(unsigned long *v)
199{
200 WARN_ON(system_state != SYSTEM_BOOTING);
201 return arch_get_random_seed_long(v);
202}
203#endif
204
205#ifndef arch_get_random_long_early
206static inline bool __init arch_get_random_long_early(unsigned long *v)
207{
208 WARN_ON(system_state != SYSTEM_BOOTING);
209 return arch_get_random_long(v);
210}
211#endif
212
213/* Pseudo random number generator from numerical recipes. */
214static inline u32 next_pseudo_random32(u32 seed)
215{
216 return seed * 1664525 + 1013904223;
217}
218
219#endif /* _LINUX_RANDOM_H */