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Linux/include/linux/random.h

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  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 

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