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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 | /* SPDX-License-Identifier: GPL-2.0 */ #ifndef _LINUX_RANDOM_H #define _LINUX_RANDOM_H #include <linux/bug.h> #include <linux/kernel.h> #include <linux/list.h> #include <linux/once.h> #include <uapi/linux/random.h> struct notifier_block; void add_device_randomness(const void *buf, size_t len); void __init add_bootloader_randomness(const void *buf, size_t len); void add_input_randomness(unsigned int type, unsigned int code, unsigned int value) __latent_entropy; void add_interrupt_randomness(int irq) __latent_entropy; void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy); static inline void add_latent_entropy(void) { #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__) add_device_randomness((const void *)&latent_entropy, sizeof(latent_entropy)); #else add_device_randomness(NULL, 0); #endif } #if IS_ENABLED(CONFIG_VMGENID) void add_vmfork_randomness(const void *unique_vm_id, size_t len); int register_random_vmfork_notifier(struct notifier_block *nb); int unregister_random_vmfork_notifier(struct notifier_block *nb); #else static inline int register_random_vmfork_notifier(struct notifier_block *nb) { return 0; } static inline int unregister_random_vmfork_notifier(struct notifier_block *nb) { return 0; } #endif void get_random_bytes(void *buf, size_t len); u8 get_random_u8(void); u16 get_random_u16(void); u32 get_random_u32(void); u64 get_random_u64(void); static inline unsigned long get_random_long(void) { #if BITS_PER_LONG == 64 return get_random_u64(); #else return get_random_u32(); #endif } u32 __get_random_u32_below(u32 ceil); /* * Returns a random integer in the interval [0, ceil), with uniform * distribution, suitable for all uses. Fastest when ceil is a constant, but * still fast for variable ceil as well. */ static inline u32 get_random_u32_below(u32 ceil) { if (!__builtin_constant_p(ceil)) return __get_random_u32_below(ceil); /* * For the fast path, below, all operations on ceil are precomputed by * the compiler, so this incurs no overhead for checking pow2, doing * divisions, or branching based on integer size. The resultant * algorithm does traditional reciprocal multiplication (typically * optimized by the compiler into shifts and adds), rejecting samples * whose lower half would indicate a range indivisible by ceil. */ BUILD_BUG_ON_MSG(!ceil, "get_random_u32_below() must take ceil > 0"); if (ceil <= 1) return 0; for (;;) { if (ceil <= 1U << 8) { u32 mult = ceil * get_random_u8(); if (likely(is_power_of_2(ceil) || (u8)mult >= (1U << 8) % ceil)) return mult >> 8; } else if (ceil <= 1U << 16) { u32 mult = ceil * get_random_u16(); if (likely(is_power_of_2(ceil) || (u16)mult >= (1U << 16) % ceil)) return mult >> 16; } else { u64 mult = (u64)ceil * get_random_u32(); if (likely(is_power_of_2(ceil) || (u32)mult >= -ceil % ceil)) return mult >> 32; } } } /* * Returns a random integer in the interval (floor, U32_MAX], with uniform * distribution, suitable for all uses. Fastest when floor is a constant, but * still fast for variable floor as well. */ static inline u32 get_random_u32_above(u32 floor) { BUILD_BUG_ON_MSG(__builtin_constant_p(floor) && floor == U32_MAX, "get_random_u32_above() must take floor < U32_MAX"); return floor + 1 + get_random_u32_below(U32_MAX - floor); } /* * Returns a random integer in the interval [floor, ceil], with uniform * distribution, suitable for all uses. Fastest when floor and ceil are * constant, but still fast for variable floor and ceil as well. */ static inline u32 get_random_u32_inclusive(u32 floor, u32 ceil) { BUILD_BUG_ON_MSG(__builtin_constant_p(floor) && __builtin_constant_p(ceil) && (floor > ceil || ceil - floor == U32_MAX), "get_random_u32_inclusive() must take floor <= ceil"); return floor + get_random_u32_below(ceil - floor + 1); } /* * On 64-bit architectures, protect against non-terminated C string overflows * by zeroing out the first byte of the canary; this leaves 56 bits of entropy. */ #ifdef CONFIG_64BIT # ifdef __LITTLE_ENDIAN # define CANARY_MASK 0xffffffffffffff00UL # else /* big endian, 64 bits: */ # define CANARY_MASK 0x00ffffffffffffffUL # endif #else /* 32 bits: */ # define CANARY_MASK 0xffffffffUL #endif static inline unsigned long get_random_canary(void) { return get_random_long() & CANARY_MASK; } void __init random_init_early(const char *command_line); void __init random_init(void); bool rng_is_initialized(void); int wait_for_random_bytes(void); /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes). * Returns the result of the call to wait_for_random_bytes. */ static inline int get_random_bytes_wait(void *buf, size_t nbytes) { int ret = wait_for_random_bytes(); get_random_bytes(buf, nbytes); return ret; } #define declare_get_random_var_wait(name, ret_type) \ static inline int get_random_ ## name ## _wait(ret_type *out) { \ int ret = wait_for_random_bytes(); \ if (unlikely(ret)) \ return ret; \ *out = get_random_ ## name(); \ return 0; \ } declare_get_random_var_wait(u8, u8) declare_get_random_var_wait(u16, u16) declare_get_random_var_wait(u32, u32) declare_get_random_var_wait(u64, u32) declare_get_random_var_wait(long, unsigned long) #undef declare_get_random_var /* * This is designed to be standalone for just prandom * users, but for now we include it from <linux/random.h> * for legacy reasons. */ #include <linux/prandom.h> #include <asm/archrandom.h> /* * Called from the boot CPU during startup; not valid to call once * secondary CPUs are up and preemption is possible. */ #ifndef arch_get_random_seed_longs_early static inline size_t __init arch_get_random_seed_longs_early(unsigned long *v, size_t max_longs) { WARN_ON(system_state != SYSTEM_BOOTING); return arch_get_random_seed_longs(v, max_longs); } #endif #ifndef arch_get_random_longs_early static inline bool __init arch_get_random_longs_early(unsigned long *v, size_t max_longs) { WARN_ON(system_state != SYSTEM_BOOTING); return arch_get_random_longs(v, max_longs); } #endif #ifdef CONFIG_SMP int random_prepare_cpu(unsigned int cpu); int random_online_cpu(unsigned int cpu); #endif #ifndef MODULE extern const struct file_operations random_fops, urandom_fops; #endif #endif /* _LINUX_RANDOM_H */ |