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 if (unlikely(ret))
89 return ret;
90 get_random_bytes(buf, nbytes);
91 return 0;
92 }
93
94 #define declare_get_random_var_wait(var) \
95 static inline int get_random_ ## var ## _wait(var *out) { \
96 int ret = wait_for_random_bytes(); \
97 if (unlikely(ret)) \
98 return ret; \
99 *out = get_random_ ## var(); \
100 return 0; \
101 }
102 declare_get_random_var_wait(u32)
103 declare_get_random_var_wait(u64)
104 declare_get_random_var_wait(int)
105 declare_get_random_var_wait(long)
106 #undef declare_get_random_var
107
108 unsigned long randomize_page(unsigned long start, unsigned long range);
109
110 u32 prandom_u32(void);
111 void prandom_bytes(void *buf, size_t nbytes);
112 void prandom_seed(u32 seed);
113 void prandom_reseed_late(void);
114
115 struct rnd_state {
116 __u32 s1, s2, s3, s4;
117 };
118
119 u32 prandom_u32_state(struct rnd_state *state);
120 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
121 void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
122
123 #define prandom_init_once(pcpu_state) \
124 DO_ONCE(prandom_seed_full_state, (pcpu_state))
125
126 /**
127 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
128 * @ep_ro: right open interval endpoint
129 *
130 * Returns a pseudo-random number that is in interval [0, ep_ro). Note
131 * that the result depends on PRNG being well distributed in [0, ~0U]
132 * u32 space. Here we use maximally equidistributed combined Tausworthe
133 * generator, that is, prandom_u32(). This is useful when requesting a
134 * random index of an array containing ep_ro elements, for example.
135 *
136 * Returns: pseudo-random number in interval [0, ep_ro)
137 */
138 static inline u32 prandom_u32_max(u32 ep_ro)
139 {
140 return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
141 }
142
143 /*
144 * Handle minimum values for seeds
145 */
146 static inline u32 __seed(u32 x, u32 m)
147 {
148 return (x < m) ? x + m : x;
149 }
150
151 /**
152 * prandom_seed_state - set seed for prandom_u32_state().
153 * @state: pointer to state structure to receive the seed.
154 * @seed: arbitrary 64-bit value to use as a seed.
155 */
156 static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
157 {
158 u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
159
160 state->s1 = __seed(i, 2U);
161 state->s2 = __seed(i, 8U);
162 state->s3 = __seed(i, 16U);
163 state->s4 = __seed(i, 128U);
164 }
165
166 #ifdef CONFIG_ARCH_RANDOM
167 # include <asm/archrandom.h>
168 #else
169 static inline bool arch_get_random_long(unsigned long *v)
170 {
171 return 0;
172 }
173 static inline bool arch_get_random_int(unsigned int *v)
174 {
175 return 0;
176 }
177 static inline bool arch_has_random(void)
178 {
179 return 0;
180 }
181 static inline bool arch_get_random_seed_long(unsigned long *v)
182 {
183 return 0;
184 }
185 static inline bool arch_get_random_seed_int(unsigned int *v)
186 {
187 return 0;
188 }
189 static inline bool arch_has_random_seed(void)
190 {
191 return 0;
192 }
193 #endif
194
195 /* Pseudo random number generator from numerical recipes. */
196 static inline u32 next_pseudo_random32(u32 seed)
197 {
198 return seed * 1664525 + 1013904223;
199 }
200
201 #endif /* _LINUX_RANDOM_H */
202
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