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 get_random_bytes(buf, nbytes); 89 return ret; 90 } 91 92 #define declare_get_random_var_wait(var) \ 93 static inline int get_random_ ## var ## _wait(var *out) { \ 94 int ret = wait_for_random_bytes(); \ 95 if (unlikely(ret)) \ 96 return ret; \ 97 *out = get_random_ ## var(); \ 98 return 0; \ 99 } 100 declare_get_random_var_wait(u32) 101 declare_get_random_var_wait(u64) 102 declare_get_random_var_wait(int) 103 declare_get_random_var_wait(long) 104 #undef declare_get_random_var 105 106 unsigned long randomize_page(unsigned long start, unsigned long range); 107 108 u32 prandom_u32(void); 109 void prandom_bytes(void *buf, size_t nbytes); 110 void prandom_seed(u32 seed); 111 void prandom_reseed_late(void); 112 113 struct rnd_state { 114 __u32 s1, s2, s3, s4; 115 }; 116 117 u32 prandom_u32_state(struct rnd_state *state); 118 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes); 119 void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state); 120 121 #define prandom_init_once(pcpu_state) \ 122 DO_ONCE(prandom_seed_full_state, (pcpu_state)) 123 124 /** 125 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro) 126 * @ep_ro: right open interval endpoint 127 * 128 * Returns a pseudo-random number that is in interval [0, ep_ro). Note 129 * that the result depends on PRNG being well distributed in [0, ~0U] 130 * u32 space. Here we use maximally equidistributed combined Tausworthe 131 * generator, that is, prandom_u32(). This is useful when requesting a 132 * random index of an array containing ep_ro elements, for example. 133 * 134 * Returns: pseudo-random number in interval [0, ep_ro) 135 */ 136 static inline u32 prandom_u32_max(u32 ep_ro) 137 { 138 return (u32)(((u64) prandom_u32() * ep_ro) >> 32); 139 } 140 141 /* 142 * Handle minimum values for seeds 143 */ 144 static inline u32 __seed(u32 x, u32 m) 145 { 146 return (x < m) ? x + m : x; 147 } 148 149 /** 150 * prandom_seed_state - set seed for prandom_u32_state(). 151 * @state: pointer to state structure to receive the seed. 152 * @seed: arbitrary 64-bit value to use as a seed. 153 */ 154 static inline void prandom_seed_state(struct rnd_state *state, u64 seed) 155 { 156 u32 i = (seed >> 32) ^ (seed << 10) ^ seed; 157 158 state->s1 = __seed(i, 2U); 159 state->s2 = __seed(i, 8U); 160 state->s3 = __seed(i, 16U); 161 state->s4 = __seed(i, 128U); 162 } 163 164 #ifdef CONFIG_ARCH_RANDOM 165 # include <asm/archrandom.h> 166 #else 167 static inline bool arch_get_random_long(unsigned long *v) 168 { 169 return 0; 170 } 171 static inline bool arch_get_random_int(unsigned int *v) 172 { 173 return 0; 174 } 175 static inline bool arch_has_random(void) 176 { 177 return 0; 178 } 179 static inline bool arch_get_random_seed_long(unsigned long *v) 180 { 181 return 0; 182 } 183 static inline bool arch_get_random_seed_int(unsigned int *v) 184 { 185 return 0; 186 } 187 static inline bool arch_has_random_seed(void) 188 { 189 return 0; 190 } 191 #endif 192 193 /* Pseudo random number generator from numerical recipes. */ 194 static inline u32 next_pseudo_random32(u32 seed) 195 { 196 return seed * 1664525 + 1013904223; 197 } 198 199 #endif /* _LINUX_RANDOM_H */ 200