2 * include/linux/random.h
4 * Include file for the random number generator.
6 #ifndef _LINUX_RANDOM_H
7 #define _LINUX_RANDOM_H
9 #include <linux/list.h>
10 #include <linux/once.h>
12 #include <uapi/linux/random.h>
14 struct random_ready_callback {
15 struct list_head list;
16 void (*func)(struct random_ready_callback *rdy);
20 extern void add_device_randomness(const void *, unsigned int);
22 #if defined(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) && !defined(__CHECKER__)
23 static inline void add_latent_entropy(void)
25 add_device_randomness((const void *)&latent_entropy,
26 sizeof(latent_entropy));
29 static inline void add_latent_entropy(void) {}
32 extern void add_input_randomness(unsigned int type, unsigned int code,
33 unsigned int value) __latent_entropy;
34 extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;
36 extern void get_random_bytes(void *buf, int nbytes);
37 extern int wait_for_random_bytes(void);
38 extern int add_random_ready_callback(struct random_ready_callback *rdy);
39 extern void del_random_ready_callback(struct random_ready_callback *rdy);
40 extern void get_random_bytes_arch(void *buf, int nbytes);
43 extern const struct file_operations random_fops, urandom_fops;
46 u32 get_random_u32(void);
47 u64 get_random_u64(void);
48 static inline unsigned int get_random_int(void)
50 return get_random_u32();
52 static inline unsigned long get_random_long(void)
54 #if BITS_PER_LONG == 64
55 return get_random_u64();
57 return get_random_u32();
62 * On 64-bit architectures, protect against non-terminated C string overflows
63 * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
66 # ifdef __LITTLE_ENDIAN
67 # define CANARY_MASK 0xffffffffffffff00UL
68 # else /* big endian, 64 bits: */
69 # define CANARY_MASK 0x00ffffffffffffffUL
72 # define CANARY_MASK 0xffffffffUL
75 static inline unsigned long get_random_canary(void)
77 unsigned long val = get_random_long();
79 return val & CANARY_MASK;
82 /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
83 * Returns the result of the call to wait_for_random_bytes. */
84 static inline int get_random_bytes_wait(void *buf, int nbytes)
86 int ret = wait_for_random_bytes();
89 get_random_bytes(buf, nbytes);
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(); \
98 *out = get_random_ ## var(); \
101 declare_get_random_var_wait(u32)
102 declare_get_random_var_wait(u64)
103 declare_get_random_var_wait(int)
104 declare_get_random_var_wait(long)
105 #undef declare_get_random_var
107 unsigned long randomize_page(unsigned long start, unsigned long range);
109 u32 prandom_u32(void);
110 void prandom_bytes(void *buf, size_t nbytes);
111 void prandom_seed(u32 seed);
112 void prandom_reseed_late(void);
115 __u32 s1, s2, s3, s4;
118 u32 prandom_u32_state(struct rnd_state *state);
119 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
120 void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
122 #define prandom_init_once(pcpu_state) \
123 DO_ONCE(prandom_seed_full_state, (pcpu_state))
126 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
127 * @ep_ro: right open interval endpoint
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.
135 * Returns: pseudo-random number in interval [0, ep_ro)
137 static inline u32 prandom_u32_max(u32 ep_ro)
139 return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
143 * Handle minimum values for seeds
145 static inline u32 __seed(u32 x, u32 m)
147 return (x < m) ? x + m : x;
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.
155 static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
157 u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
159 state->s1 = __seed(i, 2U);
160 state->s2 = __seed(i, 8U);
161 state->s3 = __seed(i, 16U);
162 state->s4 = __seed(i, 128U);
165 #ifdef CONFIG_ARCH_RANDOM
166 # include <asm/archrandom.h>
168 static inline bool arch_get_random_long(unsigned long *v)
172 static inline bool arch_get_random_int(unsigned int *v)
176 static inline bool arch_has_random(void)
180 static inline bool arch_get_random_seed_long(unsigned long *v)
184 static inline bool arch_get_random_seed_int(unsigned int *v)
188 static inline bool arch_has_random_seed(void)
194 /* Pseudo random number generator from numerical recipes. */
195 static inline u32 next_pseudo_random32(u32 seed)
197 return seed * 1664525 + 1013904223;
200 #endif /* _LINUX_RANDOM_H */