123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205 |
- /* 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 */
|