1 /* SPDX-License-Identifier: GPL-2.0 */
3 * include/linux/random.h
5 * Include file for the random number generator.
7 #ifndef _LINUX_RANDOM_H
8 #define _LINUX_RANDOM_H
10 #include <linux/bug.h>
11 #include <linux/kernel.h>
12 #include <linux/list.h>
13 #include <linux/once.h>
15 #include <uapi/linux/random.h>
17 struct random_ready_callback {
18 struct list_head list;
19 void (*func)(struct random_ready_callback *rdy);
23 extern void add_device_randomness(const void *, unsigned int);
24 extern void add_bootloader_randomness(const void *, unsigned int);
26 #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
27 static inline void add_latent_entropy(void)
29 add_device_randomness((const void *)&latent_entropy,
30 sizeof(latent_entropy));
33 static inline void add_latent_entropy(void) {}
36 extern void add_input_randomness(unsigned int type, unsigned int code,
37 unsigned int value) __latent_entropy;
38 extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;
40 extern void get_random_bytes(void *buf, int nbytes);
41 extern int wait_for_random_bytes(void);
42 extern int __init rand_initialize(void);
43 extern bool rng_is_initialized(void);
44 extern int add_random_ready_callback(struct random_ready_callback *rdy);
45 extern void del_random_ready_callback(struct random_ready_callback *rdy);
46 extern int __must_check get_random_bytes_arch(void *buf, int nbytes);
49 extern const struct file_operations random_fops, urandom_fops;
52 u32 get_random_u32(void);
53 u64 get_random_u64(void);
54 static inline unsigned int get_random_int(void)
56 return get_random_u32();
58 static inline unsigned long get_random_long(void)
60 #if BITS_PER_LONG == 64
61 return get_random_u64();
63 return get_random_u32();
68 * On 64-bit architectures, protect against non-terminated C string overflows
69 * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
72 # ifdef __LITTLE_ENDIAN
73 # define CANARY_MASK 0xffffffffffffff00UL
74 # else /* big endian, 64 bits: */
75 # define CANARY_MASK 0x00ffffffffffffffUL
78 # define CANARY_MASK 0xffffffffUL
81 static inline unsigned long get_random_canary(void)
83 unsigned long val = get_random_long();
85 return val & CANARY_MASK;
88 /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
89 * Returns the result of the call to wait_for_random_bytes. */
90 static inline int get_random_bytes_wait(void *buf, int nbytes)
92 int ret = wait_for_random_bytes();
93 get_random_bytes(buf, nbytes);
97 #define declare_get_random_var_wait(var) \
98 static inline int get_random_ ## var ## _wait(var *out) { \
99 int ret = wait_for_random_bytes(); \
102 *out = get_random_ ## var(); \
105 declare_get_random_var_wait(u32)
106 declare_get_random_var_wait(u64)
107 declare_get_random_var_wait(int)
108 declare_get_random_var_wait(long)
109 #undef declare_get_random_var
111 unsigned long randomize_page(unsigned long start, unsigned long range);
113 u32 prandom_u32(void);
114 void prandom_bytes(void *buf, size_t nbytes);
115 void prandom_seed(u32 seed);
116 void prandom_reseed_late(void);
119 __u32 s1, s2, s3, s4;
122 u32 prandom_u32_state(struct rnd_state *state);
123 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
124 void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
126 #define prandom_init_once(pcpu_state) \
127 DO_ONCE(prandom_seed_full_state, (pcpu_state))
130 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
131 * @ep_ro: right open interval endpoint
133 * Returns a pseudo-random number that is in interval [0, ep_ro). Note
134 * that the result depends on PRNG being well distributed in [0, ~0U]
135 * u32 space. Here we use maximally equidistributed combined Tausworthe
136 * generator, that is, prandom_u32(). This is useful when requesting a
137 * random index of an array containing ep_ro elements, for example.
139 * Returns: pseudo-random number in interval [0, ep_ro)
141 static inline u32 prandom_u32_max(u32 ep_ro)
143 return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
147 * Handle minimum values for seeds
149 static inline u32 __seed(u32 x, u32 m)
151 return (x < m) ? x + m : x;
155 * prandom_seed_state - set seed for prandom_u32_state().
156 * @state: pointer to state structure to receive the seed.
157 * @seed: arbitrary 64-bit value to use as a seed.
159 static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
161 u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
163 state->s1 = __seed(i, 2U);
164 state->s2 = __seed(i, 8U);
165 state->s3 = __seed(i, 16U);
166 state->s4 = __seed(i, 128U);
169 #ifdef CONFIG_ARCH_RANDOM
170 # include <asm/archrandom.h>
172 static inline bool __must_check arch_get_random_long(unsigned long *v)
176 static inline bool __must_check arch_get_random_int(unsigned int *v)
180 static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
184 static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
191 * Called from the boot CPU during startup; not valid to call once
192 * secondary CPUs are up and preemption is possible.
194 #ifndef arch_get_random_seed_long_early
195 static inline bool __init arch_get_random_seed_long_early(unsigned long *v)
197 WARN_ON(system_state != SYSTEM_BOOTING);
198 return arch_get_random_seed_long(v);
202 #ifndef arch_get_random_long_early
203 static inline bool __init arch_get_random_long_early(unsigned long *v)
205 WARN_ON(system_state != SYSTEM_BOOTING);
206 return arch_get_random_long(v);
210 /* Pseudo random number generator from numerical recipes. */
211 static inline u32 next_pseudo_random32(u32 seed)
213 return seed * 1664525 + 1013904223;
216 #endif /* _LINUX_RANDOM_H */