root/include/linux/random.h

INCLUDED FROM

DEFINITIONS

1. add_latent_entropy
2. add_latent_entropy
3. add_input_randomness
4. get_random_long
5. get_random_canary
6. get_random_bytes_wait
7. declare_get_random_var_wait
8. prandom_u32_max
9. __seed
10. prandom_seed_state
11. arch_get_random_long
12. arch_get_random_int
13. arch_has_random
14. arch_get_random_seed_long
15. arch_get_random_seed_int
16. arch_has_random_seed
17. next_pseudo_random32

   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 
  15 struct random_ready_callback {
  16         struct list_head list;
  17         void (*func)(struct random_ready_callback *rdy);
  18         struct module *owner;
  19 };
  20 
  21 extern void add_device_randomness(const void *, unsigned int);
  22 extern void add_bootloader_randomness(const void *, unsigned int);
  23 
  24 #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
  25 static inline void add_latent_entropy(void)
  26 {
  27         add_device_randomness((const void *)&latent_entropy,
  28                               sizeof(latent_entropy));
  29 }
  30 #else
  31 static inline void add_latent_entropy(void) {}
  32 #endif
  33 
  34 extern void add_input_randomness(unsigned int type, unsigned int code,
  35                                  unsigned int value) __latent_entropy;
  36 extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;
  37 
  38 extern void get_random_bytes(void *buf, int nbytes);
  39 extern int wait_for_random_bytes(void);
  40 extern int __init rand_initialize(void);
  41 extern bool rng_is_initialized(void);
  42 extern int add_random_ready_callback(struct random_ready_callback *rdy);
  43 extern void del_random_ready_callback(struct random_ready_callback *rdy);
  44 extern int __must_check get_random_bytes_arch(void *buf, int nbytes);
  45 
  46 #ifndef MODULE
  47 extern const struct file_operations random_fops, urandom_fops;
  48 #endif
  49 
  50 u32 get_random_u32(void);
  51 u64 get_random_u64(void);
  52 static inline unsigned int get_random_int(void)
  53 {
  54         return get_random_u32();
  55 }
  56 static inline unsigned long get_random_long(void)
  57 {
  58 #if BITS_PER_LONG == 64
  59         return get_random_u64();
  60 #else
  61         return get_random_u32();
  62 #endif
  63 }
  64 
  65 /*
  66  * On 64-bit architectures, protect against non-terminated C string overflows
  67  * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
  68  */
  69 #ifdef CONFIG_64BIT
  70 # ifdef __LITTLE_ENDIAN
  71 #  define CANARY_MASK 0xffffffffffffff00UL
  72 # else /* big endian, 64 bits: */
  73 #  define CANARY_MASK 0x00ffffffffffffffUL
  74 # endif
  75 #else /* 32 bits: */
  76 # define CANARY_MASK 0xffffffffUL
  77 #endif
  78 
  79 static inline unsigned long get_random_canary(void)
  80 {
  81         unsigned long val = get_random_long();
  82 
  83         return val & CANARY_MASK;
  84 }
  85 
  86 /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
  87  * Returns the result of the call to wait_for_random_bytes. */
  88 static inline int get_random_bytes_wait(void *buf, int nbytes)
  89 {
  90         int ret = wait_for_random_bytes();
  91         get_random_bytes(buf, nbytes);
  92         return ret;
  93 }
  94 
  95 #define declare_get_random_var_wait(var) \
  96         static inline int get_random_ ## var ## _wait(var *out) { \
  97                 int ret = wait_for_random_bytes(); \
  98                 if (unlikely(ret)) \
  99                         return ret; \
 100                 *out = get_random_ ## var(); \
 101                 return 0; \
 102         }
 103 declare_get_random_var_wait(u32)
 104 declare_get_random_var_wait(u64)
 105 declare_get_random_var_wait(int)
 106 declare_get_random_var_wait(long)
 107 #undef declare_get_random_var
 108 
 109 unsigned long randomize_page(unsigned long start, unsigned long range);
 110 
 111 u32 prandom_u32(void);
 112 void prandom_bytes(void *buf, size_t nbytes);
 113 void prandom_seed(u32 seed);
 114 void prandom_reseed_late(void);
 115 
 116 struct rnd_state {
 117         __u32 s1, s2, s3, s4;
 118 };
 119 
 120 u32 prandom_u32_state(struct rnd_state *state);
 121 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
 122 void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
 123 
 124 #define prandom_init_once(pcpu_state)                   \
 125         DO_ONCE(prandom_seed_full_state, (pcpu_state))
 126 
 127 /**
 128  * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
 129  * @ep_ro: right open interval endpoint
 130  *
 131  * Returns a pseudo-random number that is in interval [0, ep_ro). Note
 132  * that the result depends on PRNG being well distributed in [0, ~0U]
 133  * u32 space. Here we use maximally equidistributed combined Tausworthe
 134  * generator, that is, prandom_u32(). This is useful when requesting a
 135  * random index of an array containing ep_ro elements, for example.
 136  *
 137  * Returns: pseudo-random number in interval [0, ep_ro)
 138  */
 139 static inline u32 prandom_u32_max(u32 ep_ro)
 140 {
 141         return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
 142 }
 143 
 144 /*
 145  * Handle minimum values for seeds
 146  */
 147 static inline u32 __seed(u32 x, u32 m)
 148 {
 149         return (x < m) ? x + m : x;
 150 }
 151 
 152 /**
 153  * prandom_seed_state - set seed for prandom_u32_state().
 154  * @state: pointer to state structure to receive the seed.
 155  * @seed: arbitrary 64-bit value to use as a seed.
 156  */
 157 static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
 158 {
 159         u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
 160 
 161         state->s1 = __seed(i,   2U);
 162         state->s2 = __seed(i,   8U);
 163         state->s3 = __seed(i,  16U);
 164         state->s4 = __seed(i, 128U);
 165 }
 166 
 167 #ifdef CONFIG_ARCH_RANDOM
 168 # include <asm/archrandom.h>
 169 #else
 170 static inline bool arch_get_random_long(unsigned long *v)
 171 {
 172         return 0;
 173 }
 174 static inline bool arch_get_random_int(unsigned int *v)
 175 {
 176         return 0;
 177 }
 178 static inline bool arch_has_random(void)
 179 {
 180         return 0;
 181 }
 182 static inline bool arch_get_random_seed_long(unsigned long *v)
 183 {
 184         return 0;
 185 }
 186 static inline bool arch_get_random_seed_int(unsigned int *v)
 187 {
 188         return 0;
 189 }
 190 static inline bool arch_has_random_seed(void)
 191 {
 192         return 0;
 193 }
 194 #endif
 195 
 196 /* Pseudo random number generator from numerical recipes. */
 197 static inline u32 next_pseudo_random32(u32 seed)
 198 {
 199         return seed * 1664525 + 1013904223;
 200 }
 201 
 202 #endif /* _LINUX_RANDOM_H */