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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 bool rng_is_initialized(void);
 40 extern int add_random_ready_callback(struct random_ready_callback *rdy);
 41 extern void del_random_ready_callback(struct random_ready_callback *rdy);
 42 extern int __must_check get_random_bytes_arch(void *buf, int nbytes);
 43 
 44 #ifndef MODULE
 45 extern const struct file_operations random_fops, urandom_fops;
 46 #endif
 47 
 48 u32 get_random_u32(void);
 49 u64 get_random_u64(void);
 50 static inline unsigned int get_random_int(void)
 51 {
 52         return get_random_u32();
 53 }
 54 static inline unsigned long get_random_long(void)
 55 {
 56 #if BITS_PER_LONG == 64
 57         return get_random_u64();
 58 #else
 59         return get_random_u32();
 60 #endif
 61 }
 62 
 63 /*
 64  * On 64-bit architectures, protect against non-terminated C string overflows
 65  * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
 66  */
 67 #ifdef CONFIG_64BIT
 68 # ifdef __LITTLE_ENDIAN
 69 #  define CANARY_MASK 0xffffffffffffff00UL
 70 # else /* big endian, 64 bits: */
 71 #  define CANARY_MASK 0x00ffffffffffffffUL
 72 # endif
 73 #else /* 32 bits: */
 74 # define CANARY_MASK 0xffffffffUL
 75 #endif
 76 
 77 static inline unsigned long get_random_canary(void)
 78 {
 79         unsigned long val = get_random_long();
 80 
 81         return val & CANARY_MASK;
 82 }
 83 
 84 /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
 85  * Returns the result of the call to wait_for_random_bytes. */
 86 static inline int get_random_bytes_wait(void *buf, int nbytes)
 87 {
 88         int ret = wait_for_random_bytes();
 89         get_random_bytes(buf, nbytes);
 90         return ret;
 91 }
 92 
 93 #define declare_get_random_var_wait(var) \
 94         static inline int get_random_ ## var ## _wait(var *out) { \
 95                 int ret = wait_for_random_bytes(); \
 96                 if (unlikely(ret)) \
 97                         return ret; \
 98                 *out = get_random_ ## var(); \
 99                 return 0; \
100         }
101 declare_get_random_var_wait(u32)
102 declare_get_random_var_wait(u64)
103 declare_get_random_var_wait(int)
104 declare_get_random_var_wait(long)
105 #undef declare_get_random_var
106 
107 unsigned long randomize_page(unsigned long start, unsigned long range);
108 
109 u32 prandom_u32(void);
110 void prandom_bytes(void *buf, size_t nbytes);
111 void prandom_seed(u32 seed);
112 void prandom_reseed_late(void);
113 
114 struct rnd_state {
115         __u32 s1, s2, s3, s4;
116 };
117 
118 u32 prandom_u32_state(struct rnd_state *state);
119 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
120 void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
121 
122 #define prandom_init_once(pcpu_state)                   \
123         DO_ONCE(prandom_seed_full_state, (pcpu_state))
124 
125 /**
126  * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
127  * @ep_ro: right open interval endpoint
128  *
129  * Returns a pseudo-random number that is in interval [0, ep_ro). Note
130  * that the result depends on PRNG being well distributed in [0, ~0U]
131  * u32 space. Here we use maximally equidistributed combined Tausworthe
132  * generator, that is, prandom_u32(). This is useful when requesting a
133  * random index of an array containing ep_ro elements, for example.
134  *
135  * Returns: pseudo-random number in interval [0, ep_ro)
136  */
137 static inline u32 prandom_u32_max(u32 ep_ro)
138 {
139         return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
140 }
141 
142 /*
143  * Handle minimum values for seeds
144  */
145 static inline u32 __seed(u32 x, u32 m)
146 {
147         return (x < m) ? x + m : x;
148 }
149 
150 /**
151  * prandom_seed_state - set seed for prandom_u32_state().
152  * @state: pointer to state structure to receive the seed.
153  * @seed: arbitrary 64-bit value to use as a seed.
154  */
155 static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
156 {
157         u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
158 
159         state->s1 = __seed(i,   2U);
160         state->s2 = __seed(i,   8U);
161         state->s3 = __seed(i,  16U);
162         state->s4 = __seed(i, 128U);
163 }
164 
165 #ifdef CONFIG_ARCH_RANDOM
166 # include <asm/archrandom.h>
167 #else
168 static inline bool arch_get_random_long(unsigned long *v)
169 {
170         return 0;
171 }
172 static inline bool arch_get_random_int(unsigned int *v)
173 {
174         return 0;
175 }
176 static inline bool arch_has_random(void)
177 {
178         return 0;
179 }
180 static inline bool arch_get_random_seed_long(unsigned long *v)
181 {
182         return 0;
183 }
184 static inline bool arch_get_random_seed_int(unsigned int *v)
185 {
186         return 0;
187 }
188 static inline bool arch_has_random_seed(void)
189 {
190         return 0;
191 }
192 #endif
193 
194 /* Pseudo random number generator from numerical recipes. */
195 static inline u32 next_pseudo_random32(u32 seed)
196 {
197         return seed * 1664525 + 1013904223;
198 }
199 
200 #endif /* _LINUX_RANDOM_H */
201 

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