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 bool rng_is_initialized(void); 40 extern int add_random_ready_callback(struct random_ready_callback *rdy); 41 extern void del_random_ready_callback(struct random_ready_callback *rdy); 42 extern int __must_check get_random_bytes_arch(void *buf, int nbytes); 43 44 #ifndef MODULE 45 extern const struct file_operations random_fops, urandom_fops; 46 #endif 47 48 u32 get_random_u32(void); 49 u64 get_random_u64(void); 50 static inline unsigned int get_random_int(void) 51 { 52 return get_random_u32(); 53 } 54 static inline unsigned long get_random_long(void) 55 { 56 #if BITS_PER_LONG == 64 57 return get_random_u64(); 58 #else 59 return get_random_u32(); 60 #endif 61 } 62 63 /* 64 * On 64-bit architectures, protect against non-terminated C string overflows 65 * by zeroing out the first byte of the canary; this leaves 56 bits of entropy. 66 */ 67 #ifdef CONFIG_64BIT 68 # ifdef __LITTLE_ENDIAN 69 # define CANARY_MASK 0xffffffffffffff00UL 70 # else /* big endian, 64 bits: */ 71 # define CANARY_MASK 0x00ffffffffffffffUL 72 # endif 73 #else /* 32 bits: */ 74 # define CANARY_MASK 0xffffffffUL 75 #endif 76 77 static inline unsigned long get_random_canary(void) 78 { 79 unsigned long val = get_random_long(); 80 81 return val & CANARY_MASK; 82 } 83 84 /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes). 85 * Returns the result of the call to wait_for_random_bytes. */ 86 static inline int get_random_bytes_wait(void *buf, int nbytes) 87 { 88 int ret = wait_for_random_bytes(); 89 get_random_bytes(buf, nbytes); 90 return ret; 91 } 92 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(); \ 96 if (unlikely(ret)) \ 97 return ret; \ 98 *out = get_random_ ## var(); \ 99 return 0; \ 100 } 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 106 107 unsigned long randomize_page(unsigned long start, unsigned long range); 108 109 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); 113 114 struct rnd_state { 115 __u32 s1, s2, s3, s4; 116 }; 117 118 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); 121 122 #define prandom_init_once(pcpu_state) \ 123 DO_ONCE(prandom_seed_full_state, (pcpu_state)) 124 125 /** 126 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro) 127 * @ep_ro: right open interval endpoint 128 * 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. 134 * 135 * Returns: pseudo-random number in interval [0, ep_ro) 136 */ 137 static inline u32 prandom_u32_max(u32 ep_ro) 138 { 139 return (u32)(((u64) prandom_u32() * ep_ro) >> 32); 140 } 141 142 /* 143 * Handle minimum values for seeds 144 */ 145 static inline u32 __seed(u32 x, u32 m) 146 { 147 return (x < m) ? x + m : x; 148 } 149 150 /** 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. 154 */ 155 static inline void prandom_seed_state(struct rnd_state *state, u64 seed) 156 { 157 u32 i = (seed >> 32) ^ (seed << 10) ^ seed; 158 159 state->s1 = __seed(i, 2U); 160 state->s2 = __seed(i, 8U); 161 state->s3 = __seed(i, 16U); 162 state->s4 = __seed(i, 128U); 163 } 164 165 #ifdef CONFIG_ARCH_RANDOM 166 # include <asm/archrandom.h> 167 #else 168 static inline bool arch_get_random_long(unsigned long *v) 169 { 170 return 0; 171 } 172 static inline bool arch_get_random_int(unsigned int *v) 173 { 174 return 0; 175 } 176 static inline bool arch_has_random(void) 177 { 178 return 0; 179 } 180 static inline bool arch_get_random_seed_long(unsigned long *v) 181 { 182 return 0; 183 } 184 static inline bool arch_get_random_seed_int(unsigned int *v) 185 { 186 return 0; 187 } 188 static inline bool arch_has_random_seed(void) 189 { 190 return 0; 191 } 192 #endif 193 194 /* Pseudo random number generator from numerical recipes. */ 195 static inline u32 next_pseudo_random32(u32 seed) 196 { 197 return seed * 1664525 + 1013904223; 198 } 199 200 #endif /* _LINUX_RANDOM_H */ 201