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