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(LATENT_ENTROPY_PLUGIN) && !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 __init rand_initialize(void); 40 extern bool rng_is_initialized(void); 41 extern int add_random_ready_callback(struct random_ready_callback *rdy); 42 extern void del_random_ready_callback(struct random_ready_callback *rdy); 43 extern int __must_check get_random_bytes_arch(void *buf, int nbytes); 44 45 #ifndef MODULE 46 extern const struct file_operations random_fops, urandom_fops; 47 #endif 48 49 u32 get_random_u32(void); 50 u64 get_random_u64(void); 51 static inline unsigned int get_random_int(void) 52 { 53 return get_random_u32(); 54 } 55 static inline unsigned long get_random_long(void) 56 { 57 #if BITS_PER_LONG == 64 58 return get_random_u64(); 59 #else 60 return get_random_u32(); 61 #endif 62 } 63 64 /* 65 * On 64-bit architectures, protect against non-terminated C string overflows 66 * by zeroing out the first byte of the canary; this leaves 56 bits of entropy. 67 */ 68 #ifdef CONFIG_64BIT 69 # ifdef __LITTLE_ENDIAN 70 # define CANARY_MASK 0xffffffffffffff00UL 71 # else /* big endian, 64 bits: */ 72 # define CANARY_MASK 0x00ffffffffffffffUL 73 # endif 74 #else /* 32 bits: */ 75 # define CANARY_MASK 0xffffffffUL 76 #endif 77 78 static inline unsigned long get_random_canary(void) 79 { 80 unsigned long val = get_random_long(); 81 82 return val & CANARY_MASK; 83 } 84 85 /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes). 86 * Returns the result of the call to wait_for_random_bytes. */ 87 static inline int get_random_bytes_wait(void *buf, int nbytes) 88 { 89 int ret = wait_for_random_bytes(); 90 get_random_bytes(buf, nbytes); 91 return ret; 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 */ 202