linux-stable/include/linux/random.h
Daniel Borkmann 897ece56e7 random32: add prandom_init_once helper for own rngs
Add a prandom_init_once() facility that works on the rnd_state, so that
users that are keeping their own state independent from prandom_u32() can
initialize their taus113 per cpu states.

The motivation here is similar to net_get_random_once(): initialize the
state as late as possible in the hope that enough entropy has been
collected for the seeding. prandom_init_once() makes use of the recently
introduced prandom_seed_full_state() helper and is generic enough so that
it could also be used on fast-paths due to the DO_ONCE().

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-08 05:26:38 -07:00

130 lines
3.4 KiB
C

/*
* include/linux/random.h
*
* Include file for the random number generator.
*/
#ifndef _LINUX_RANDOM_H
#define _LINUX_RANDOM_H
#include <linux/list.h>
#include <linux/once.h>
#include <uapi/linux/random.h>
struct random_ready_callback {
struct list_head list;
void (*func)(struct random_ready_callback *rdy);
struct module *owner;
};
extern void add_device_randomness(const void *, unsigned int);
extern void add_input_randomness(unsigned int type, unsigned int code,
unsigned int value);
extern void add_interrupt_randomness(int irq, int irq_flags);
extern void get_random_bytes(void *buf, int nbytes);
extern int add_random_ready_callback(struct random_ready_callback *rdy);
extern void del_random_ready_callback(struct random_ready_callback *rdy);
extern void get_random_bytes_arch(void *buf, int nbytes);
void generate_random_uuid(unsigned char uuid_out[16]);
extern int random_int_secret_init(void);
#ifndef MODULE
extern const struct file_operations random_fops, urandom_fops;
#endif
unsigned int get_random_int(void);
unsigned long randomize_range(unsigned long start, unsigned long end, unsigned long len);
u32 prandom_u32(void);
void prandom_bytes(void *buf, size_t nbytes);
void prandom_seed(u32 seed);
void prandom_reseed_late(void);
struct rnd_state {
__u32 s1, s2, s3, s4;
};
u32 prandom_u32_state(struct rnd_state *state);
void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
#define prandom_init_once(pcpu_state) \
DO_ONCE(prandom_seed_full_state, (pcpu_state))
/**
* prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
* @ep_ro: right open interval endpoint
*
* Returns a pseudo-random number that is in interval [0, ep_ro). Note
* that the result depends on PRNG being well distributed in [0, ~0U]
* u32 space. Here we use maximally equidistributed combined Tausworthe
* generator, that is, prandom_u32(). This is useful when requesting a
* random index of an array containing ep_ro elements, for example.
*
* Returns: pseudo-random number in interval [0, ep_ro)
*/
static inline u32 prandom_u32_max(u32 ep_ro)
{
return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
}
/*
* Handle minimum values for seeds
*/
static inline u32 __seed(u32 x, u32 m)
{
return (x < m) ? x + m : x;
}
/**
* prandom_seed_state - set seed for prandom_u32_state().
* @state: pointer to state structure to receive the seed.
* @seed: arbitrary 64-bit value to use as a seed.
*/
static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
{
u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
state->s1 = __seed(i, 2U);
state->s2 = __seed(i, 8U);
state->s3 = __seed(i, 16U);
state->s4 = __seed(i, 128U);
}
#ifdef CONFIG_ARCH_RANDOM
# include <asm/archrandom.h>
#else
static inline int arch_get_random_long(unsigned long *v)
{
return 0;
}
static inline int arch_get_random_int(unsigned int *v)
{
return 0;
}
static inline int arch_has_random(void)
{
return 0;
}
static inline int arch_get_random_seed_long(unsigned long *v)
{
return 0;
}
static inline int arch_get_random_seed_int(unsigned int *v)
{
return 0;
}
static inline int arch_has_random_seed(void)
{
return 0;
}
#endif
/* Pseudo random number generator from numerical recipes. */
static inline u32 next_pseudo_random32(u32 seed)
{
return seed * 1664525 + 1013904223;
}
#endif /* _LINUX_RANDOM_H */