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/bug.h> 11 #include <linux/kernel.h> 12 #include <linux/list.h> 13 #include <linux/once.h> 14 #include <asm/percpu.h> 15 16 #include <uapi/linux/random.h> 17 18 struct random_ready_callback { 19 struct list_head list; 20 void (*func)(struct random_ready_callback *rdy); 21 struct module *owner; 22 }; 23 24 extern void add_device_randomness(const void *, unsigned int); 25 extern void add_bootloader_randomness(const void *, unsigned int); 26 27 #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__) 28 static inline void add_latent_entropy(void) 29 { 30 add_device_randomness((const void *)&latent_entropy, 31 sizeof(latent_entropy)); 32 } 33 #else 34 static inline void add_latent_entropy(void) {} 35 #endif 36 37 extern void add_input_randomness(unsigned int type, unsigned int code, 38 unsigned int value) __latent_entropy; 39 extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy; 40 41 extern void get_random_bytes(void *buf, int nbytes); 42 extern int wait_for_random_bytes(void); 43 extern int __init rand_initialize(void); 44 extern bool rng_is_initialized(void); 45 extern int add_random_ready_callback(struct random_ready_callback *rdy); 46 extern void del_random_ready_callback(struct random_ready_callback *rdy); 47 extern int __must_check get_random_bytes_arch(void *buf, int nbytes); 48 49 #ifndef MODULE 50 extern const struct file_operations random_fops, urandom_fops; 51 #endif 52 53 u32 get_random_u32(void); 54 u64 get_random_u64(void); 55 static inline unsigned int get_random_int(void) 56 { 57 return get_random_u32(); 58 } 59 static inline unsigned long get_random_long(void) 60 { 61 #if BITS_PER_LONG == 64 62 return get_random_u64(); 63 #else 64 return get_random_u32(); 65 #endif 66 } 67 68 /* 69 * On 64-bit architectures, protect against non-terminated C string overflows 70 * by zeroing out the first byte of the canary; this leaves 56 bits of entropy. 71 */ 72 #ifdef CONFIG_64BIT 73 # ifdef __LITTLE_ENDIAN 74 # define CANARY_MASK 0xffffffffffffff00UL 75 # else /* big endian, 64 bits: */ 76 # define CANARY_MASK 0x00ffffffffffffffUL 77 # endif 78 #else /* 32 bits: */ 79 # define CANARY_MASK 0xffffffffUL 80 #endif 81 82 static inline unsigned long get_random_canary(void) 83 { 84 unsigned long val = get_random_long(); 85 86 return val & CANARY_MASK; 87 } 88 89 /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes). 90 * Returns the result of the call to wait_for_random_bytes. */ 91 static inline int get_random_bytes_wait(void *buf, int nbytes) 92 { 93 int ret = wait_for_random_bytes(); 94 get_random_bytes(buf, nbytes); 95 return ret; 96 } 97 98 #define declare_get_random_var_wait(var) \ 99 static inline int get_random_ ## var ## _wait(var *out) { \ 100 int ret = wait_for_random_bytes(); \ 101 if (unlikely(ret)) \ 102 return ret; \ 103 *out = get_random_ ## var(); \ 104 return 0; \ 105 } 106 declare_get_random_var_wait(u32) 107 declare_get_random_var_wait(u64) 108 declare_get_random_var_wait(int) 109 declare_get_random_var_wait(long) 110 #undef declare_get_random_var 111 112 unsigned long randomize_page(unsigned long start, unsigned long range); 113 114 u32 prandom_u32(void); 115 void prandom_bytes(void *buf, size_t nbytes); 116 void prandom_seed(u32 seed); 117 void prandom_reseed_late(void); 118 119 struct rnd_state { 120 __u32 s1, s2, s3, s4; 121 }; 122 123 DECLARE_PER_CPU(struct rnd_state, net_rand_state); 124 125 u32 prandom_u32_state(struct rnd_state *state); 126 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes); 127 void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state); 128 129 #define prandom_init_once(pcpu_state) \ 130 DO_ONCE(prandom_seed_full_state, (pcpu_state)) 131 132 /** 133 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro) 134 * @ep_ro: right open interval endpoint 135 * 136 * Returns a pseudo-random number that is in interval [0, ep_ro). Note 137 * that the result depends on PRNG being well distributed in [0, ~0U] 138 * u32 space. Here we use maximally equidistributed combined Tausworthe 139 * generator, that is, prandom_u32(). This is useful when requesting a 140 * random index of an array containing ep_ro elements, for example. 141 * 142 * Returns: pseudo-random number in interval [0, ep_ro) 143 */ 144 static inline u32 prandom_u32_max(u32 ep_ro) 145 { 146 return (u32)(((u64) prandom_u32() * ep_ro) >> 32); 147 } 148 149 /* 150 * Handle minimum values for seeds 151 */ 152 static inline u32 __seed(u32 x, u32 m) 153 { 154 return (x < m) ? x + m : x; 155 } 156 157 /** 158 * prandom_seed_state - set seed for prandom_u32_state(). 159 * @state: pointer to state structure to receive the seed. 160 * @seed: arbitrary 64-bit value to use as a seed. 161 */ 162 static inline void prandom_seed_state(struct rnd_state *state, u64 seed) 163 { 164 u32 i = (seed >> 32) ^ (seed << 10) ^ seed; 165 166 state->s1 = __seed(i, 2U); 167 state->s2 = __seed(i, 8U); 168 state->s3 = __seed(i, 16U); 169 state->s4 = __seed(i, 128U); 170 } 171 172 #ifdef CONFIG_ARCH_RANDOM 173 # include <asm/archrandom.h> 174 #else 175 static inline bool __must_check arch_get_random_long(unsigned long *v) 176 { 177 return false; 178 } 179 static inline bool __must_check arch_get_random_int(unsigned int *v) 180 { 181 return false; 182 } 183 static inline bool __must_check arch_get_random_seed_long(unsigned long *v) 184 { 185 return false; 186 } 187 static inline bool __must_check arch_get_random_seed_int(unsigned int *v) 188 { 189 return false; 190 } 191 #endif 192 193 /* 194 * Called from the boot CPU during startup; not valid to call once 195 * secondary CPUs are up and preemption is possible. 196 */ 197 #ifndef arch_get_random_seed_long_early 198 static inline bool __init arch_get_random_seed_long_early(unsigned long *v) 199 { 200 WARN_ON(system_state != SYSTEM_BOOTING); 201 return arch_get_random_seed_long(v); 202 } 203 #endif 204 205 #ifndef arch_get_random_long_early 206 static inline bool __init arch_get_random_long_early(unsigned long *v) 207 { 208 WARN_ON(system_state != SYSTEM_BOOTING); 209 return arch_get_random_long(v); 210 } 211 #endif 212 213 /* Pseudo random number generator from numerical recipes. */ 214 static inline u32 next_pseudo_random32(u32 seed) 215 { 216 return seed * 1664525 + 1013904223; 217 } 218 219 #endif /* _LINUX_RANDOM_H */ 220