1 /* 2 * include/linux/random.h 3 * 4 * Include file for the random number generator. 5 */ 6 #ifndef _LINUX_RANDOM_H 7 #define _LINUX_RANDOM_H 8 9 #include <linux/list.h> 10 #include <linux/once.h> 11 12 #include <uapi/linux/random.h> 13 14 struct random_ready_callback { 15 struct list_head list; 16 void (*func)(struct random_ready_callback *rdy); 17 struct module *owner; 18 }; 19 20 extern void add_device_randomness(const void *, unsigned int); 21 22 #if defined(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) && !defined(__CHECKER__) 23 static inline void add_latent_entropy(void) 24 { 25 add_device_randomness((const void *)&latent_entropy, 26 sizeof(latent_entropy)); 27 } 28 #else 29 static inline void add_latent_entropy(void) {} 30 #endif 31 32 extern void add_input_randomness(unsigned int type, unsigned int code, 33 unsigned int value) __latent_entropy; 34 extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy; 35 36 extern void get_random_bytes(void *buf, int nbytes); 37 extern int add_random_ready_callback(struct random_ready_callback *rdy); 38 extern void del_random_ready_callback(struct random_ready_callback *rdy); 39 extern void get_random_bytes_arch(void *buf, int nbytes); 40 41 #ifndef MODULE 42 extern const struct file_operations random_fops, urandom_fops; 43 #endif 44 45 u32 get_random_u32(void); 46 u64 get_random_u64(void); 47 static inline unsigned int get_random_int(void) 48 { 49 return get_random_u32(); 50 } 51 static inline unsigned long get_random_long(void) 52 { 53 #if BITS_PER_LONG == 64 54 return get_random_u64(); 55 #else 56 return get_random_u32(); 57 #endif 58 } 59 60 /* 61 * On 64-bit architectures, protect against non-terminated C string overflows 62 * by zeroing out the first byte of the canary; this leaves 56 bits of entropy. 63 */ 64 #ifdef CONFIG_64BIT 65 # ifdef __LITTLE_ENDIAN 66 # define CANARY_MASK 0xffffffffffffff00UL 67 # else /* big endian, 64 bits: */ 68 # define CANARY_MASK 0x00ffffffffffffffUL 69 # endif 70 #else /* 32 bits: */ 71 # define CANARY_MASK 0xffffffffUL 72 #endif 73 74 static inline unsigned long get_random_canary(void) 75 { 76 unsigned long val = get_random_long(); 77 78 return val & CANARY_MASK; 79 } 80 81 unsigned long randomize_page(unsigned long start, unsigned long range); 82 83 u32 prandom_u32(void); 84 void prandom_bytes(void *buf, size_t nbytes); 85 void prandom_seed(u32 seed); 86 void prandom_reseed_late(void); 87 88 struct rnd_state { 89 __u32 s1, s2, s3, s4; 90 }; 91 92 u32 prandom_u32_state(struct rnd_state *state); 93 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes); 94 void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state); 95 96 #define prandom_init_once(pcpu_state) \ 97 DO_ONCE(prandom_seed_full_state, (pcpu_state)) 98 99 /** 100 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro) 101 * @ep_ro: right open interval endpoint 102 * 103 * Returns a pseudo-random number that is in interval [0, ep_ro). Note 104 * that the result depends on PRNG being well distributed in [0, ~0U] 105 * u32 space. Here we use maximally equidistributed combined Tausworthe 106 * generator, that is, prandom_u32(). This is useful when requesting a 107 * random index of an array containing ep_ro elements, for example. 108 * 109 * Returns: pseudo-random number in interval [0, ep_ro) 110 */ 111 static inline u32 prandom_u32_max(u32 ep_ro) 112 { 113 return (u32)(((u64) prandom_u32() * ep_ro) >> 32); 114 } 115 116 /* 117 * Handle minimum values for seeds 118 */ 119 static inline u32 __seed(u32 x, u32 m) 120 { 121 return (x < m) ? x + m : x; 122 } 123 124 /** 125 * prandom_seed_state - set seed for prandom_u32_state(). 126 * @state: pointer to state structure to receive the seed. 127 * @seed: arbitrary 64-bit value to use as a seed. 128 */ 129 static inline void prandom_seed_state(struct rnd_state *state, u64 seed) 130 { 131 u32 i = (seed >> 32) ^ (seed << 10) ^ seed; 132 133 state->s1 = __seed(i, 2U); 134 state->s2 = __seed(i, 8U); 135 state->s3 = __seed(i, 16U); 136 state->s4 = __seed(i, 128U); 137 } 138 139 #ifdef CONFIG_ARCH_RANDOM 140 # include <asm/archrandom.h> 141 #else 142 static inline bool arch_get_random_long(unsigned long *v) 143 { 144 return 0; 145 } 146 static inline bool arch_get_random_int(unsigned int *v) 147 { 148 return 0; 149 } 150 static inline bool arch_has_random(void) 151 { 152 return 0; 153 } 154 static inline bool arch_get_random_seed_long(unsigned long *v) 155 { 156 return 0; 157 } 158 static inline bool arch_get_random_seed_int(unsigned int *v) 159 { 160 return 0; 161 } 162 static inline bool arch_has_random_seed(void) 163 { 164 return 0; 165 } 166 #endif 167 168 /* Pseudo random number generator from numerical recipes. */ 169 static inline u32 next_pseudo_random32(u32 seed) 170 { 171 return seed * 1664525 + 1013904223; 172 } 173 174 #endif /* _LINUX_RANDOM_H */ 175