include/linux/random.h

   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
  23 #if defined(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) && !defined(__CHECKER__)
  24 static inline void add_latent_entropy(void)
  25 {
  26         add_device_randomness((const void *)&latent_entropy,
  27                               sizeof(latent_entropy));
  28 }
  29 #else
  30 static inline void add_latent_entropy(void) {}
  31 #endif
  32
  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;
  36
  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);
  42
  43 #ifndef MODULE
  44 extern const struct file_operations random_fops, urandom_fops;
  45 #endif
  46
  47 u32 get_random_u32(void);
  48 u64 get_random_u64(void);
  49 static inline unsigned int get_random_int(void)
  50 {
  51         return get_random_u32();
  52 }
  53 static inline unsigned long get_random_long(void)
  54 {
  55 #if BITS_PER_LONG == 64
  56         return get_random_u64();
  57 #else
  58         return get_random_u32();
  59 #endif
  60 }
  61
  62 /*
  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.
  65  */
  66 #ifdef CONFIG_64BIT
  67 # ifdef __LITTLE_ENDIAN
  68 #  define CANARY_MASK 0xffffffffffffff00UL
  69 # else /* big endian, 64 bits: */
  70 #  define CANARY_MASK 0x00ffffffffffffffUL
  71 # endif
  72 #else /* 32 bits: */
  73 # define CANARY_MASK 0xffffffffUL
  74 #endif
  75
  76 static inline unsigned long get_random_canary(void)
  77 {
  78         unsigned long val = get_random_long();
  79
  80         return val & CANARY_MASK;
  81 }
  82
  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)
  86 {
  87         int ret = wait_for_random_bytes();
  88         if (unlikely(ret))
  89                 return ret;
  90         get_random_bytes(buf, nbytes);
  91         return 0;
  92 }
  93
  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(); \
  97                 if (unlikely(ret)) \
  98                         return ret; \
  99                 *out = get_random_ ## var(); \
 100                 return 0; \
 101         }
 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
 107
 108 unsigned long randomize_page(unsigned long start, unsigned long range);
 109
 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);
 114
 115 struct rnd_state {
 116         __u32 s1, s2, s3, s4;
 117 };
 118
 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);
 122
 123 #define prandom_init_once(pcpu_state)                   \
 124         DO_ONCE(prandom_seed_full_state, (pcpu_state))
 125
 126 /**
 127  * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
 128  * @ep_ro: right open interval endpoint
 129  *
 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.
 135  *
 136  * Returns: pseudo-random number in interval [0, ep_ro)
 137  */
 138 static inline u32 prandom_u32_max(u32 ep_ro)
 139 {
 140         return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
 141 }
 142
 143 /*
 144  * Handle minimum values for seeds
 145  */
 146 static inline u32 __seed(u32 x, u32 m)
 147 {
 148         return (x < m) ? x + m : x;
 149 }
 150
 151 /**
 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.
 155  */
 156 static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
 157 {
 158         u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
 159
 160         state->s1 = __seed(i,   2U);
 161         state->s2 = __seed(i,   8U);
 162         state->s3 = __seed(i,  16U);
 163         state->s4 = __seed(i, 128U);
 164 }
 165
 166 #ifdef CONFIG_ARCH_RANDOM
 167 # include <asm/archrandom.h>
 168 #else
 169 static inline bool arch_get_random_long(unsigned long *v)
 170 {
 171         return 0;
 172 }
 173 static inline bool arch_get_random_int(unsigned int *v)
 174 {
 175         return 0;
 176 }
 177 static inline bool arch_has_random(void)
 178 {
 179         return 0;
 180 }
 181 static inline bool arch_get_random_seed_long(unsigned long *v)
 182 {
 183         return 0;
 184 }
 185 static inline bool arch_get_random_seed_int(unsigned int *v)
 186 {
 187         return 0;
 188 }
 189 static inline bool arch_has_random_seed(void)
 190 {
 191         return 0;
 192 }
 193 #endif
 194
 195 /* Pseudo random number generator from numerical recipes. */
 196 static inline u32 next_pseudo_random32(u32 seed)
 197 {
 198         return seed * 1664525 + 1013904223;
 199 }
 200
 201 #endif /* _LINUX_RANDOM_H */