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/list.h>
11 #include <linux/once.h>
13 #include <uapi/linux/random.h>
15 struct random_ready_callback
{
16 struct list_head list
;
17 void (*func
)(struct random_ready_callback
*rdy
);
21 extern void add_device_randomness(const void *, unsigned int);
23 #if defined(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) && !defined(__CHECKER__)
24 static inline void add_latent_entropy(void)
26 add_device_randomness((const void *)&latent_entropy
,
27 sizeof(latent_entropy
));
30 static inline void add_latent_entropy(void) {}
33 extern void add_input_randomness(unsigned int type
, unsigned int code
,
34 unsigned int value
) __latent_entropy
;
35 extern void add_interrupt_randomness(int irq
, int irq_flags
) __latent_entropy
;
37 extern void get_random_bytes(void *buf
, int nbytes
);
38 extern int wait_for_random_bytes(void);
39 extern int add_random_ready_callback(struct random_ready_callback
*rdy
);
40 extern void del_random_ready_callback(struct random_ready_callback
*rdy
);
41 extern void get_random_bytes_arch(void *buf
, int nbytes
);
44 extern const struct file_operations random_fops
, urandom_fops
;
47 u32
get_random_u32(void);
48 u64
get_random_u64(void);
49 static inline unsigned int get_random_int(void)
51 return get_random_u32();
53 static inline unsigned long get_random_long(void)
55 #if BITS_PER_LONG == 64
56 return get_random_u64();
58 return get_random_u32();
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.
67 # ifdef __LITTLE_ENDIAN
68 # define CANARY_MASK 0xffffffffffffff00UL
69 # else /* big endian, 64 bits: */
70 # define CANARY_MASK 0x00ffffffffffffffUL
73 # define CANARY_MASK 0xffffffffUL
76 static inline unsigned long get_random_canary(void)
78 unsigned long val
= get_random_long();
80 return val
& CANARY_MASK
;
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. */
85 static inline int get_random_bytes_wait(void *buf
, int nbytes
)
87 int ret
= wait_for_random_bytes();
90 get_random_bytes(buf
, nbytes
);
94 #define declare_get_random_var_wait(var) \
95 static inline int get_random_ ## var ## _wait(var *out) { \
96 int ret = wait_for_random_bytes(); \
99 *out = get_random_ ## var(); \
102 declare_get_random_var_wait(u32
)
103 declare_get_random_var_wait(u64
)
104 declare_get_random_var_wait(int)
105 declare_get_random_var_wait(long)
106 #undef declare_get_random_var
108 unsigned long randomize_page(unsigned long start
, unsigned long range
);
110 u32
prandom_u32(void);
111 void prandom_bytes(void *buf
, size_t nbytes
);
112 void prandom_seed(u32 seed
);
113 void prandom_reseed_late(void);
116 __u32 s1
, s2
, s3
, s4
;
119 u32
prandom_u32_state(struct rnd_state
*state
);
120 void prandom_bytes_state(struct rnd_state
*state
, void *buf
, size_t nbytes
);
121 void prandom_seed_full_state(struct rnd_state __percpu
*pcpu_state
);
123 #define prandom_init_once(pcpu_state) \
124 DO_ONCE(prandom_seed_full_state, (pcpu_state))
127 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
128 * @ep_ro: right open interval endpoint
130 * Returns a pseudo-random number that is in interval [0, ep_ro). Note
131 * that the result depends on PRNG being well distributed in [0, ~0U]
132 * u32 space. Here we use maximally equidistributed combined Tausworthe
133 * generator, that is, prandom_u32(). This is useful when requesting a
134 * random index of an array containing ep_ro elements, for example.
136 * Returns: pseudo-random number in interval [0, ep_ro)
138 static inline u32
prandom_u32_max(u32 ep_ro
)
140 return (u32
)(((u64
) prandom_u32() * ep_ro
) >> 32);
144 * Handle minimum values for seeds
146 static inline u32
__seed(u32 x
, u32 m
)
148 return (x
< m
) ? x
+ m
: x
;
152 * prandom_seed_state - set seed for prandom_u32_state().
153 * @state: pointer to state structure to receive the seed.
154 * @seed: arbitrary 64-bit value to use as a seed.
156 static inline void prandom_seed_state(struct rnd_state
*state
, u64 seed
)
158 u32 i
= (seed
>> 32) ^ (seed
<< 10) ^ seed
;
160 state
->s1
= __seed(i
, 2U);
161 state
->s2
= __seed(i
, 8U);
162 state
->s3
= __seed(i
, 16U);
163 state
->s4
= __seed(i
, 128U);
166 #ifdef CONFIG_ARCH_RANDOM
167 # include <asm/archrandom.h>
169 static inline bool arch_get_random_long(unsigned long *v
)
173 static inline bool arch_get_random_int(unsigned int *v
)
177 static inline bool arch_has_random(void)
181 static inline bool arch_get_random_seed_long(unsigned long *v
)
185 static inline bool arch_get_random_seed_int(unsigned int *v
)
189 static inline bool arch_has_random_seed(void)
195 /* Pseudo random number generator from numerical recipes. */
196 static inline u32
next_pseudo_random32(u32 seed
)
198 return seed
* 1664525 + 1013904223;
201 #endif /* _LINUX_RANDOM_H */