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