| 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 | |
| 10 | #include <uapi/linux/random.h> |
| 11 | |
| 12 | struct notifier_block; |
| 13 | |
| 14 | void add_device_randomness(const void *buf, size_t len); |
| 15 | void __init add_bootloader_randomness(const void *buf, size_t len); |
| 16 | void add_input_randomness(unsigned int type, unsigned int code, |
| 17 | unsigned int value) __latent_entropy; |
| 18 | void add_interrupt_randomness(int irq) __latent_entropy; |
| 19 | void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy, bool sleep_after); |
| 20 | |
| 21 | static inline void add_latent_entropy(void) |
| 22 | { |
| 23 | #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__) |
| 24 | add_device_randomness((const void *)&latent_entropy, sizeof(latent_entropy)); |
| 25 | #else |
| 26 | add_device_randomness(NULL, 0); |
| 27 | #endif |
| 28 | } |
| 29 | |
| 30 | #if IS_ENABLED(CONFIG_VMGENID) |
| 31 | void add_vmfork_randomness(const void *unique_vm_id, size_t len); |
| 32 | int register_random_vmfork_notifier(struct notifier_block *nb); |
| 33 | int unregister_random_vmfork_notifier(struct notifier_block *nb); |
| 34 | #else |
| 35 | static inline int register_random_vmfork_notifier(struct notifier_block *nb) { return 0; } |
| 36 | static inline int unregister_random_vmfork_notifier(struct notifier_block *nb) { return 0; } |
| 37 | #endif |
| 38 | |
| 39 | void get_random_bytes(void *buf, size_t len); |
| 40 | u8 get_random_u8(void); |
| 41 | u16 get_random_u16(void); |
| 42 | u32 get_random_u32(void); |
| 43 | u64 get_random_u64(void); |
| 44 | static inline unsigned long get_random_long(void) |
| 45 | { |
| 46 | #if BITS_PER_LONG == 64 |
| 47 | return get_random_u64(); |
| 48 | #else |
| 49 | return get_random_u32(); |
| 50 | #endif |
| 51 | } |
| 52 | |
| 53 | u32 __get_random_u32_below(u32 ceil); |
| 54 | |
| 55 | /* |
| 56 | * Returns a random integer in the interval [0, ceil), with uniform |
| 57 | * distribution, suitable for all uses. Fastest when ceil is a constant, but |
| 58 | * still fast for variable ceil as well. |
| 59 | */ |
| 60 | static inline u32 get_random_u32_below(u32 ceil) |
| 61 | { |
| 62 | if (!__builtin_constant_p(ceil)) |
| 63 | return __get_random_u32_below(ceil); |
| 64 | |
| 65 | /* |
| 66 | * For the fast path, below, all operations on ceil are precomputed by |
| 67 | * the compiler, so this incurs no overhead for checking pow2, doing |
| 68 | * divisions, or branching based on integer size. The resultant |
| 69 | * algorithm does traditional reciprocal multiplication (typically |
| 70 | * optimized by the compiler into shifts and adds), rejecting samples |
| 71 | * whose lower half would indicate a range indivisible by ceil. |
| 72 | */ |
| 73 | BUILD_BUG_ON_MSG(!ceil, "get_random_u32_below() must take ceil > 0"); |
| 74 | if (ceil <= 1) |
| 75 | return 0; |
| 76 | for (;;) { |
| 77 | if (ceil <= 1U << 8) { |
| 78 | u32 mult = ceil * get_random_u8(); |
| 79 | if (likely(is_power_of_2(ceil) || (u8)mult >= (1U << 8) % ceil)) |
| 80 | return mult >> 8; |
| 81 | } else if (ceil <= 1U << 16) { |
| 82 | u32 mult = ceil * get_random_u16(); |
| 83 | if (likely(is_power_of_2(ceil) || (u16)mult >= (1U << 16) % ceil)) |
| 84 | return mult >> 16; |
| 85 | } else { |
| 86 | u64 mult = (u64)ceil * get_random_u32(); |
| 87 | if (likely(is_power_of_2(ceil) || (u32)mult >= -ceil % ceil)) |
| 88 | return mult >> 32; |
| 89 | } |
| 90 | } |
| 91 | } |
| 92 | |
| 93 | /* |
| 94 | * Returns a random integer in the interval (floor, U32_MAX], with uniform |
| 95 | * distribution, suitable for all uses. Fastest when floor is a constant, but |
| 96 | * still fast for variable floor as well. |
| 97 | */ |
| 98 | static inline u32 get_random_u32_above(u32 floor) |
| 99 | { |
| 100 | BUILD_BUG_ON_MSG(__builtin_constant_p(floor) && floor == U32_MAX, |
| 101 | "get_random_u32_above() must take floor < U32_MAX"); |
| 102 | return floor + 1 + get_random_u32_below(U32_MAX - floor); |
| 103 | } |
| 104 | |
| 105 | /* |
| 106 | * Returns a random integer in the interval [floor, ceil], with uniform |
| 107 | * distribution, suitable for all uses. Fastest when floor and ceil are |
| 108 | * constant, but still fast for variable floor and ceil as well. |
| 109 | */ |
| 110 | static inline u32 get_random_u32_inclusive(u32 floor, u32 ceil) |
| 111 | { |
| 112 | BUILD_BUG_ON_MSG(__builtin_constant_p(floor) && __builtin_constant_p(ceil) && |
| 113 | (floor > ceil || ceil - floor == U32_MAX), |
| 114 | "get_random_u32_inclusive() must take floor <= ceil"); |
| 115 | return floor + get_random_u32_below(ceil - floor + 1); |
| 116 | } |
| 117 | |
| 118 | void __init random_init_early(const char *command_line); |
| 119 | void __init random_init(void); |
| 120 | bool rng_is_initialized(void); |
| 121 | int wait_for_random_bytes(void); |
| 122 | int execute_with_initialized_rng(struct notifier_block *nb); |
| 123 | |
| 124 | /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes). |
| 125 | * Returns the result of the call to wait_for_random_bytes. */ |
| 126 | static inline int get_random_bytes_wait(void *buf, size_t nbytes) |
| 127 | { |
| 128 | int ret = wait_for_random_bytes(); |
| 129 | get_random_bytes(buf, nbytes); |
| 130 | return ret; |
| 131 | } |
| 132 | |
| 133 | #define declare_get_random_var_wait(name, ret_type) \ |
| 134 | static inline int get_random_ ## name ## _wait(ret_type *out) { \ |
| 135 | int ret = wait_for_random_bytes(); \ |
| 136 | if (unlikely(ret)) \ |
| 137 | return ret; \ |
| 138 | *out = get_random_ ## name(); \ |
| 139 | return 0; \ |
| 140 | } |
| 141 | declare_get_random_var_wait(u8, u8) |
| 142 | declare_get_random_var_wait(u16, u16) |
| 143 | declare_get_random_var_wait(u32, u32) |
| 144 | declare_get_random_var_wait(u64, u32) |
| 145 | declare_get_random_var_wait(long, unsigned long) |
| 146 | #undef declare_get_random_var |
| 147 | |
| 148 | /* |
| 149 | * This is designed to be standalone for just prandom |
| 150 | * users, but for now we include it from <linux/random.h> |
| 151 | * for legacy reasons. |
| 152 | */ |
| 153 | #include <linux/prandom.h> |
| 154 | |
| 155 | #ifdef CONFIG_SMP |
| 156 | int random_prepare_cpu(unsigned int cpu); |
| 157 | int random_online_cpu(unsigned int cpu); |
| 158 | #endif |
| 159 | |
| 160 | #ifndef MODULE |
| 161 | extern const struct file_operations random_fops, urandom_fops; |
| 162 | #endif |
| 163 | |
| 164 | #endif /* _LINUX_RANDOM_H */ |