include/linux/random.h

   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/bug.h>
  11 #include <linux/kernel.h>
  12 #include <linux/list.h>
  13 #include <linux/once.h>
  14
  15 #include <uapi/linux/random.h>
  16
  17 struct random_ready_callback {
  18         struct list_head list;
  19         void (*func)(struct random_ready_callback *rdy);
  20         struct module *owner;
  21 };
  22
  23 extern void add_device_randomness(const void *, unsigned int);
  24 extern void add_bootloader_randomness(const void *, unsigned int);
  25
  26 #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
  27 static inline void add_latent_entropy(void)
  28 {
  29         add_device_randomness((const void *)&latent_entropy,
  30                               sizeof(latent_entropy));
  31 }
  32 #else
  33 static inline void add_latent_entropy(void) {}
  34 #endif
  35
  36 extern void add_input_randomness(unsigned int type, unsigned int code,
  37                                  unsigned int value) __latent_entropy;
  38 extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;
  39
  40 extern void get_random_bytes(void *buf, int nbytes);
  41 extern int wait_for_random_bytes(void);
  42 extern int __init rand_initialize(void);
  43 extern bool rng_is_initialized(void);
  44 extern int add_random_ready_callback(struct random_ready_callback *rdy);
  45 extern void del_random_ready_callback(struct random_ready_callback *rdy);
  46 extern int __must_check get_random_bytes_arch(void *buf, int nbytes);
  47
  48 #ifndef MODULE
  49 extern const struct file_operations random_fops, urandom_fops;
  50 #endif
  51
  52 u32 get_random_u32(void);
  53 u64 get_random_u64(void);
  54 static inline unsigned int get_random_int(void)
  55 {
  56         return get_random_u32();
  57 }
  58 static inline unsigned long get_random_long(void)
  59 {
  60 #if BITS_PER_LONG == 64
  61         return get_random_u64();
  62 #else
  63         return get_random_u32();
  64 #endif
  65 }
  66
  67 /*
  68  * On 64-bit architectures, protect against non-terminated C string overflows
  69  * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
  70  */
  71 #ifdef CONFIG_64BIT
  72 # ifdef __LITTLE_ENDIAN
  73 #  define CANARY_MASK 0xffffffffffffff00UL
  74 # else /* big endian, 64 bits: */
  75 #  define CANARY_MASK 0x00ffffffffffffffUL
  76 # endif
  77 #else /* 32 bits: */
  78 # define CANARY_MASK 0xffffffffUL
  79 #endif
  80
  81 static inline unsigned long get_random_canary(void)
  82 {
  83         unsigned long val = get_random_long();
  84
  85         return val & CANARY_MASK;
  86 }
  87
  88 /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
  89  * Returns the result of the call to wait_for_random_bytes. */
  90 static inline int get_random_bytes_wait(void *buf, int nbytes)
  91 {
  92         int ret = wait_for_random_bytes();
  93         get_random_bytes(buf, nbytes);
  94         return ret;
  95 }
  96
  97 #define declare_get_random_var_wait(var) \
  98         static inline int get_random_ ## var ## _wait(var *out) { \
  99                 int ret = wait_for_random_bytes(); \
 100                 if (unlikely(ret)) \
 101                         return ret; \
 102                 *out = get_random_ ## var(); \
 103                 return 0; \
 104         }
 105 declare_get_random_var_wait(u32)
 106 declare_get_random_var_wait(u64)
 107 declare_get_random_var_wait(int)
 108 declare_get_random_var_wait(long)
 109 #undef declare_get_random_var
 110
 111 unsigned long randomize_page(unsigned long start, unsigned long range);
 112
 113 /*
 114  * This is designed to be standalone for just prandom
 115  * users, but for now we include it from <linux/random.h>
 116  * for legacy reasons.
 117  */
 118 #include <linux/prandom.h>
 119
 120 #ifdef CONFIG_ARCH_RANDOM
 121 # include <asm/archrandom.h>
 122 #else
 123 static inline bool __must_check arch_get_random_long(unsigned long *v)
 124 {
 125         return false;
 126 }
 127 static inline bool __must_check arch_get_random_int(unsigned int *v)
 128 {
 129         return false;
 130 }
 131 static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
 132 {
 133         return false;
 134 }
 135 static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
 136 {
 137         return false;
 138 }
 139 #endif
 140
 141 /*
 142  * Called from the boot CPU during startup; not valid to call once
 143  * secondary CPUs are up and preemption is possible.
 144  */
 145 #ifndef arch_get_random_seed_long_early
 146 static inline bool __init arch_get_random_seed_long_early(unsigned long *v)
 147 {
 148         WARN_ON(system_state != SYSTEM_BOOTING);
 149         return arch_get_random_seed_long(v);
 150 }
 151 #endif
 152
 153 #ifndef arch_get_random_long_early
 154 static inline bool __init arch_get_random_long_early(unsigned long *v)
 155 {
 156         WARN_ON(system_state != SYSTEM_BOOTING);
 157         return arch_get_random_long(v);
 158 }
 159 #endif
 160
 161 #endif /* _LINUX_RANDOM_H */