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 extern void add_bootloader_randomness(const void *, unsigned int);
23
24 #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
add_latent_entropy(void)25 static inline void add_latent_entropy(void)
26 {
27 add_device_randomness((const void *)&latent_entropy,
28 sizeof(latent_entropy));
29 }
30 #else
add_latent_entropy(void)31 static inline void add_latent_entropy(void) {}
32 #endif
33
34 extern void add_input_randomness(unsigned int type, unsigned int code,
35 unsigned int value) __latent_entropy;
36 extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;
37
38 extern void get_random_bytes(void *buf, int nbytes);
39 extern int wait_for_random_bytes(void);
40 extern int __init rand_initialize(void);
41 extern bool rng_is_initialized(void);
42 extern int add_random_ready_callback(struct random_ready_callback *rdy);
43 extern void del_random_ready_callback(struct random_ready_callback *rdy);
44 extern int __must_check get_random_bytes_arch(void *buf, int nbytes);
45
46 #ifndef MODULE
47 extern const struct file_operations random_fops, urandom_fops;
48 #endif
49
50 u32 get_random_u32(void);
51 u64 get_random_u64(void);
get_random_int(void)52 static inline unsigned int get_random_int(void)
53 {
54 return get_random_u32();
55 }
get_random_long(void)56 static inline unsigned long get_random_long(void)
57 {
58 #if BITS_PER_LONG == 64
59 return get_random_u64();
60 #else
61 return get_random_u32();
62 #endif
63 }
64
65 /*
66 * On 64-bit architectures, protect against non-terminated C string overflows
67 * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
68 */
69 #ifdef CONFIG_64BIT
70 # ifdef __LITTLE_ENDIAN
71 # define CANARY_MASK 0xffffffffffffff00UL
72 # else /* big endian, 64 bits: */
73 # define CANARY_MASK 0x00ffffffffffffffUL
74 # endif
75 #else /* 32 bits: */
76 # define CANARY_MASK 0xffffffffUL
77 #endif
78
get_random_canary(void)79 static inline unsigned long get_random_canary(void)
80 {
81 unsigned long val = get_random_long();
82
83 return val & CANARY_MASK;
84 }
85
86 /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
87 * Returns the result of the call to wait_for_random_bytes. */
get_random_bytes_wait(void * buf,int nbytes)88 static inline int get_random_bytes_wait(void *buf, int nbytes)
89 {
90 int ret = wait_for_random_bytes();
91 get_random_bytes(buf, nbytes);
92 return ret;
93 }
94
95 #define declare_get_random_var_wait(var) \
96 static inline int get_random_ ## var ## _wait(var *out) { \
97 int ret = wait_for_random_bytes(); \
98 if (unlikely(ret)) \
99 return ret; \
100 *out = get_random_ ## var(); \
101 return 0; \
102 }
103 declare_get_random_var_wait(u32)
104 declare_get_random_var_wait(u64)
105 declare_get_random_var_wait(int)
106 declare_get_random_var_wait(long)
107 #undef declare_get_random_var
108
109 unsigned long randomize_page(unsigned long start, unsigned long range);
110
111 u32 prandom_u32(void);
112 void prandom_bytes(void *buf, size_t nbytes);
113 void prandom_seed(u32 seed);
114 void prandom_reseed_late(void);
115
116 struct rnd_state {
117 __u32 s1, s2, s3, s4;
118 };
119
120 u32 prandom_u32_state(struct rnd_state *state);
121 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
122 void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
123
124 #define prandom_init_once(pcpu_state) \
125 DO_ONCE(prandom_seed_full_state, (pcpu_state))
126
127 /**
128 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
129 * @ep_ro: right open interval endpoint
130 *
131 * Returns a pseudo-random number that is in interval [0, ep_ro). Note
132 * that the result depends on PRNG being well distributed in [0, ~0U]
133 * u32 space. Here we use maximally equidistributed combined Tausworthe
134 * generator, that is, prandom_u32(). This is useful when requesting a
135 * random index of an array containing ep_ro elements, for example.
136 *
137 * Returns: pseudo-random number in interval [0, ep_ro)
138 */
prandom_u32_max(u32 ep_ro)139 static inline u32 prandom_u32_max(u32 ep_ro)
140 {
141 return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
142 }
143
144 /*
145 * Handle minimum values for seeds
146 */
__seed(u32 x,u32 m)147 static inline u32 __seed(u32 x, u32 m)
148 {
149 return (x < m) ? x + m : x;
150 }
151
152 /**
153 * prandom_seed_state - set seed for prandom_u32_state().
154 * @state: pointer to state structure to receive the seed.
155 * @seed: arbitrary 64-bit value to use as a seed.
156 */
prandom_seed_state(struct rnd_state * state,u64 seed)157 static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
158 {
159 u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
160
161 state->s1 = __seed(i, 2U);
162 state->s2 = __seed(i, 8U);
163 state->s3 = __seed(i, 16U);
164 state->s4 = __seed(i, 128U);
165 }
166
167 #ifdef CONFIG_ARCH_RANDOM
168 # include <asm/archrandom.h>
169 #else
arch_get_random_long(unsigned long * v)170 static inline bool arch_get_random_long(unsigned long *v)
171 {
172 return 0;
173 }
arch_get_random_int(unsigned int * v)174 static inline bool arch_get_random_int(unsigned int *v)
175 {
176 return 0;
177 }
arch_has_random(void)178 static inline bool arch_has_random(void)
179 {
180 return 0;
181 }
arch_get_random_seed_long(unsigned long * v)182 static inline bool arch_get_random_seed_long(unsigned long *v)
183 {
184 return 0;
185 }
arch_get_random_seed_int(unsigned int * v)186 static inline bool arch_get_random_seed_int(unsigned int *v)
187 {
188 return 0;
189 }
arch_has_random_seed(void)190 static inline bool arch_has_random_seed(void)
191 {
192 return 0;
193 }
194 #endif
195
196 /* Pseudo random number generator from numerical recipes. */
next_pseudo_random32(u32 seed)197 static inline u32 next_pseudo_random32(u32 seed)
198 {
199 return seed * 1664525 + 1013904223;
200 }
201
202 #endif /* _LINUX_RANDOM_H */
203
