LXR linux/include/linux/random.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2
   3#ifndef _LINUX_RANDOM_H
   4#define _LINUX_RANDOM_H
   5
   6#include <linux/bug.h>
   7#include <linux/kernel.h>
   8#include <linux/list.h>
   9#include <linux/once.h>
  10
  11#include <uapi/linux/random.h>
  12
  13struct notifier_block;
  14
  15extern void add_device_randomness(const void *, size_t);
  16extern void add_bootloader_randomness(const void *, size_t);
  17
  18#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
  19static inline void add_latent_entropy(void)
  20{
  21        add_device_randomness((const void *)&latent_entropy,
  22                              sizeof(latent_entropy));
  23}
  24#else
  25static inline void add_latent_entropy(void) {}
  26#endif
  27
  28extern void add_input_randomness(unsigned int type, unsigned int code,
  29                                 unsigned int value) __latent_entropy;
  30extern void add_interrupt_randomness(int irq) __latent_entropy;
  31extern void add_hwgenerator_randomness(const void *buffer, size_t count,
  32                                       size_t entropy);
  33#if IS_ENABLED(CONFIG_VMGENID)
  34extern void add_vmfork_randomness(const void *unique_vm_id, size_t size);
  35extern int register_random_vmfork_notifier(struct notifier_block *nb);
  36extern int unregister_random_vmfork_notifier(struct notifier_block *nb);
  37#else
  38static inline int register_random_vmfork_notifier(struct notifier_block *nb) { return 0; }
  39static inline int unregister_random_vmfork_notifier(struct notifier_block *nb) { return 0; }
  40#endif
  41
  42extern void get_random_bytes(void *buf, size_t nbytes);
  43extern int wait_for_random_bytes(void);
  44extern int __init rand_initialize(void);
  45extern bool rng_is_initialized(void);
  46extern int register_random_ready_notifier(struct notifier_block *nb);
  47extern int unregister_random_ready_notifier(struct notifier_block *nb);
  48extern size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes);
  49
  50#ifndef MODULE
  51extern const struct file_operations random_fops, urandom_fops;
  52#endif
  53
  54u32 get_random_u32(void);
  55u64 get_random_u64(void);
  56static inline unsigned int get_random_int(void)
  57{
  58        return get_random_u32();
  59}
  60static inline unsigned long get_random_long(void)
  61{
  62#if BITS_PER_LONG == 64
  63        return get_random_u64();
  64#else
  65        return get_random_u32();
  66#endif
  67}
  68
  69/*
  70 * On 64-bit architectures, protect against non-terminated C string overflows
  71 * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
  72 */
  73#ifdef CONFIG_64BIT
  74# ifdef __LITTLE_ENDIAN
  75#  define CANARY_MASK 0xffffffffffffff00UL
  76# else /* big endian, 64 bits: */
  77#  define CANARY_MASK 0x00ffffffffffffffUL
  78# endif
  79#else /* 32 bits: */
  80# define CANARY_MASK 0xffffffffUL
  81#endif
  82
  83static inline unsigned long get_random_canary(void)
  84{
  85        unsigned long val = get_random_long();
  86
  87        return val & CANARY_MASK;
  88}
  89
  90/* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
  91 * Returns the result of the call to wait_for_random_bytes. */
  92static inline int get_random_bytes_wait(void *buf, size_t nbytes)
  93{
  94        int ret = wait_for_random_bytes();
  95        get_random_bytes(buf, nbytes);
  96        return ret;
  97}
  98
  99#define declare_get_random_var_wait(var) \
 100        static inline int get_random_ ## var ## _wait(var *out) { \
 101                int ret = wait_for_random_bytes(); \
 102                if (unlikely(ret)) \
 103                        return ret; \
 104                *out = get_random_ ## var(); \
 105                return 0; \
 106        }
 107declare_get_random_var_wait(u32)
 108declare_get_random_var_wait(u64)
 109declare_get_random_var_wait(int)
 110declare_get_random_var_wait(long)
 111#undef declare_get_random_var
 112
 113unsigned long randomize_page(unsigned long start, unsigned long range);
 114
 115/*
 116 * This is designed to be standalone for just prandom
 117 * users, but for now we include it from <linux/random.h>
 118 * for legacy reasons.
 119 */
 120#include <linux/prandom.h>
 121
 122#ifdef CONFIG_ARCH_RANDOM
 123# include <asm/archrandom.h>
 124#else
 125static inline bool __must_check arch_get_random_long(unsigned long *v)
 126{
 127        return false;
 128}
 129static inline bool __must_check arch_get_random_int(unsigned int *v)
 130{
 131        return false;
 132}
 133static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
 134{
 135        return false;
 136}
 137static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
 138{
 139        return false;
 140}
 141#endif
 142
 143/*
 144 * Called from the boot CPU during startup; not valid to call once
 145 * secondary CPUs are up and preemption is possible.
 146 */
 147#ifndef arch_get_random_seed_long_early
 148static inline bool __init arch_get_random_seed_long_early(unsigned long *v)
 149{
 150        WARN_ON(system_state != SYSTEM_BOOTING);
 151        return arch_get_random_seed_long(v);
 152}
 153#endif
 154
 155#ifndef arch_get_random_long_early
 156static inline bool __init arch_get_random_long_early(unsigned long *v)
 157{
 158        WARN_ON(system_state != SYSTEM_BOOTING);
 159        return arch_get_random_long(v);
 160}
 161#endif
 162
 163#ifdef CONFIG_SMP
 164extern int random_prepare_cpu(unsigned int cpu);
 165extern int random_online_cpu(unsigned int cpu);
 166#endif
 167
 168#endif /* _LINUX_RANDOM_H */
 169