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 */ 203