897ece56e7
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>
464 lines
13 KiB
C
464 lines
13 KiB
C
/*
|
|
* This is a maximally equidistributed combined Tausworthe generator
|
|
* based on code from GNU Scientific Library 1.5 (30 Jun 2004)
|
|
*
|
|
* lfsr113 version:
|
|
*
|
|
* x_n = (s1_n ^ s2_n ^ s3_n ^ s4_n)
|
|
*
|
|
* s1_{n+1} = (((s1_n & 4294967294) << 18) ^ (((s1_n << 6) ^ s1_n) >> 13))
|
|
* s2_{n+1} = (((s2_n & 4294967288) << 2) ^ (((s2_n << 2) ^ s2_n) >> 27))
|
|
* s3_{n+1} = (((s3_n & 4294967280) << 7) ^ (((s3_n << 13) ^ s3_n) >> 21))
|
|
* s4_{n+1} = (((s4_n & 4294967168) << 13) ^ (((s4_n << 3) ^ s4_n) >> 12))
|
|
*
|
|
* The period of this generator is about 2^113 (see erratum paper).
|
|
*
|
|
* From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
|
|
* Generators", Mathematics of Computation, 65, 213 (1996), 203--213:
|
|
* http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
|
|
* ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
|
|
*
|
|
* There is an erratum in the paper "Tables of Maximally Equidistributed
|
|
* Combined LFSR Generators", Mathematics of Computation, 68, 225 (1999),
|
|
* 261--269: http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
|
|
*
|
|
* ... the k_j most significant bits of z_j must be non-zero,
|
|
* for each j. (Note: this restriction also applies to the
|
|
* computer code given in [4], but was mistakenly not mentioned
|
|
* in that paper.)
|
|
*
|
|
* This affects the seeding procedure by imposing the requirement
|
|
* s1 > 1, s2 > 7, s3 > 15, s4 > 127.
|
|
*/
|
|
|
|
#include <linux/types.h>
|
|
#include <linux/percpu.h>
|
|
#include <linux/export.h>
|
|
#include <linux/jiffies.h>
|
|
#include <linux/random.h>
|
|
#include <linux/sched.h>
|
|
#include <asm/unaligned.h>
|
|
|
|
#ifdef CONFIG_RANDOM32_SELFTEST
|
|
static void __init prandom_state_selftest(void);
|
|
#else
|
|
static inline void prandom_state_selftest(void)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
static DEFINE_PER_CPU(struct rnd_state, net_rand_state);
|
|
|
|
/**
|
|
* prandom_u32_state - seeded pseudo-random number generator.
|
|
* @state: pointer to state structure holding seeded state.
|
|
*
|
|
* This is used for pseudo-randomness with no outside seeding.
|
|
* For more random results, use prandom_u32().
|
|
*/
|
|
u32 prandom_u32_state(struct rnd_state *state)
|
|
{
|
|
#define TAUSWORTHE(s, a, b, c, d) ((s & c) << d) ^ (((s << a) ^ s) >> b)
|
|
state->s1 = TAUSWORTHE(state->s1, 6U, 13U, 4294967294U, 18U);
|
|
state->s2 = TAUSWORTHE(state->s2, 2U, 27U, 4294967288U, 2U);
|
|
state->s3 = TAUSWORTHE(state->s3, 13U, 21U, 4294967280U, 7U);
|
|
state->s4 = TAUSWORTHE(state->s4, 3U, 12U, 4294967168U, 13U);
|
|
|
|
return (state->s1 ^ state->s2 ^ state->s3 ^ state->s4);
|
|
}
|
|
EXPORT_SYMBOL(prandom_u32_state);
|
|
|
|
/**
|
|
* prandom_u32 - pseudo random number generator
|
|
*
|
|
* A 32 bit pseudo-random number is generated using a fast
|
|
* algorithm suitable for simulation. This algorithm is NOT
|
|
* considered safe for cryptographic use.
|
|
*/
|
|
u32 prandom_u32(void)
|
|
{
|
|
struct rnd_state *state = &get_cpu_var(net_rand_state);
|
|
u32 res;
|
|
|
|
res = prandom_u32_state(state);
|
|
put_cpu_var(state);
|
|
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(prandom_u32);
|
|
|
|
/**
|
|
* prandom_bytes_state - get the requested number of pseudo-random bytes
|
|
*
|
|
* @state: pointer to state structure holding seeded state.
|
|
* @buf: where to copy the pseudo-random bytes to
|
|
* @bytes: the requested number of bytes
|
|
*
|
|
* This is used for pseudo-randomness with no outside seeding.
|
|
* For more random results, use prandom_bytes().
|
|
*/
|
|
void prandom_bytes_state(struct rnd_state *state, void *buf, size_t bytes)
|
|
{
|
|
u8 *ptr = buf;
|
|
|
|
while (bytes >= sizeof(u32)) {
|
|
put_unaligned(prandom_u32_state(state), (u32 *) ptr);
|
|
ptr += sizeof(u32);
|
|
bytes -= sizeof(u32);
|
|
}
|
|
|
|
if (bytes > 0) {
|
|
u32 rem = prandom_u32_state(state);
|
|
do {
|
|
*ptr++ = (u8) rem;
|
|
bytes--;
|
|
rem >>= BITS_PER_BYTE;
|
|
} while (bytes > 0);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(prandom_bytes_state);
|
|
|
|
/**
|
|
* prandom_bytes - get the requested number of pseudo-random bytes
|
|
* @buf: where to copy the pseudo-random bytes to
|
|
* @bytes: the requested number of bytes
|
|
*/
|
|
void prandom_bytes(void *buf, size_t bytes)
|
|
{
|
|
struct rnd_state *state = &get_cpu_var(net_rand_state);
|
|
|
|
prandom_bytes_state(state, buf, bytes);
|
|
put_cpu_var(state);
|
|
}
|
|
EXPORT_SYMBOL(prandom_bytes);
|
|
|
|
static void prandom_warmup(struct rnd_state *state)
|
|
{
|
|
/* Calling RNG ten times to satisfy recurrence condition */
|
|
prandom_u32_state(state);
|
|
prandom_u32_state(state);
|
|
prandom_u32_state(state);
|
|
prandom_u32_state(state);
|
|
prandom_u32_state(state);
|
|
prandom_u32_state(state);
|
|
prandom_u32_state(state);
|
|
prandom_u32_state(state);
|
|
prandom_u32_state(state);
|
|
prandom_u32_state(state);
|
|
}
|
|
|
|
static u32 __extract_hwseed(void)
|
|
{
|
|
unsigned int val = 0;
|
|
|
|
(void)(arch_get_random_seed_int(&val) ||
|
|
arch_get_random_int(&val));
|
|
|
|
return val;
|
|
}
|
|
|
|
static void prandom_seed_early(struct rnd_state *state, u32 seed,
|
|
bool mix_with_hwseed)
|
|
{
|
|
#define LCG(x) ((x) * 69069U) /* super-duper LCG */
|
|
#define HWSEED() (mix_with_hwseed ? __extract_hwseed() : 0)
|
|
state->s1 = __seed(HWSEED() ^ LCG(seed), 2U);
|
|
state->s2 = __seed(HWSEED() ^ LCG(state->s1), 8U);
|
|
state->s3 = __seed(HWSEED() ^ LCG(state->s2), 16U);
|
|
state->s4 = __seed(HWSEED() ^ LCG(state->s3), 128U);
|
|
}
|
|
|
|
/**
|
|
* prandom_seed - add entropy to pseudo random number generator
|
|
* @seed: seed value
|
|
*
|
|
* Add some additional seeding to the prandom pool.
|
|
*/
|
|
void prandom_seed(u32 entropy)
|
|
{
|
|
int i;
|
|
/*
|
|
* No locking on the CPUs, but then somewhat random results are, well,
|
|
* expected.
|
|
*/
|
|
for_each_possible_cpu(i) {
|
|
struct rnd_state *state = &per_cpu(net_rand_state, i);
|
|
|
|
state->s1 = __seed(state->s1 ^ entropy, 2U);
|
|
prandom_warmup(state);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(prandom_seed);
|
|
|
|
/*
|
|
* Generate some initially weak seeding values to allow
|
|
* to start the prandom_u32() engine.
|
|
*/
|
|
static int __init prandom_init(void)
|
|
{
|
|
int i;
|
|
|
|
prandom_state_selftest();
|
|
|
|
for_each_possible_cpu(i) {
|
|
struct rnd_state *state = &per_cpu(net_rand_state, i);
|
|
u32 weak_seed = (i + jiffies) ^ random_get_entropy();
|
|
|
|
prandom_seed_early(state, weak_seed, true);
|
|
prandom_warmup(state);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
core_initcall(prandom_init);
|
|
|
|
static void __prandom_timer(unsigned long dontcare);
|
|
|
|
static DEFINE_TIMER(seed_timer, __prandom_timer, 0, 0);
|
|
|
|
static void __prandom_timer(unsigned long dontcare)
|
|
{
|
|
u32 entropy;
|
|
unsigned long expires;
|
|
|
|
get_random_bytes(&entropy, sizeof(entropy));
|
|
prandom_seed(entropy);
|
|
|
|
/* reseed every ~60 seconds, in [40 .. 80) interval with slack */
|
|
expires = 40 + prandom_u32_max(40);
|
|
seed_timer.expires = jiffies + msecs_to_jiffies(expires * MSEC_PER_SEC);
|
|
|
|
add_timer(&seed_timer);
|
|
}
|
|
|
|
static void __init __prandom_start_seed_timer(void)
|
|
{
|
|
set_timer_slack(&seed_timer, HZ);
|
|
seed_timer.expires = jiffies + msecs_to_jiffies(40 * MSEC_PER_SEC);
|
|
add_timer(&seed_timer);
|
|
}
|
|
|
|
void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state)
|
|
{
|
|
int i;
|
|
|
|
for_each_possible_cpu(i) {
|
|
struct rnd_state *state = per_cpu_ptr(pcpu_state, i);
|
|
u32 seeds[4];
|
|
|
|
get_random_bytes(&seeds, sizeof(seeds));
|
|
state->s1 = __seed(seeds[0], 2U);
|
|
state->s2 = __seed(seeds[1], 8U);
|
|
state->s3 = __seed(seeds[2], 16U);
|
|
state->s4 = __seed(seeds[3], 128U);
|
|
|
|
prandom_warmup(state);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Generate better values after random number generator
|
|
* is fully initialized.
|
|
*/
|
|
static void __prandom_reseed(bool late)
|
|
{
|
|
unsigned long flags;
|
|
static bool latch = false;
|
|
static DEFINE_SPINLOCK(lock);
|
|
|
|
/* Asking for random bytes might result in bytes getting
|
|
* moved into the nonblocking pool and thus marking it
|
|
* as initialized. In this case we would double back into
|
|
* this function and attempt to do a late reseed.
|
|
* Ignore the pointless attempt to reseed again if we're
|
|
* already waiting for bytes when the nonblocking pool
|
|
* got initialized.
|
|
*/
|
|
|
|
/* only allow initial seeding (late == false) once */
|
|
if (!spin_trylock_irqsave(&lock, flags))
|
|
return;
|
|
|
|
if (latch && !late)
|
|
goto out;
|
|
|
|
latch = true;
|
|
prandom_seed_full_state(&net_rand_state);
|
|
out:
|
|
spin_unlock_irqrestore(&lock, flags);
|
|
}
|
|
|
|
void prandom_reseed_late(void)
|
|
{
|
|
__prandom_reseed(true);
|
|
}
|
|
|
|
static int __init prandom_reseed(void)
|
|
{
|
|
__prandom_reseed(false);
|
|
__prandom_start_seed_timer();
|
|
return 0;
|
|
}
|
|
late_initcall(prandom_reseed);
|
|
|
|
#ifdef CONFIG_RANDOM32_SELFTEST
|
|
static struct prandom_test1 {
|
|
u32 seed;
|
|
u32 result;
|
|
} test1[] = {
|
|
{ 1U, 3484351685U },
|
|
{ 2U, 2623130059U },
|
|
{ 3U, 3125133893U },
|
|
{ 4U, 984847254U },
|
|
};
|
|
|
|
static struct prandom_test2 {
|
|
u32 seed;
|
|
u32 iteration;
|
|
u32 result;
|
|
} test2[] = {
|
|
/* Test cases against taus113 from GSL library. */
|
|
{ 931557656U, 959U, 2975593782U },
|
|
{ 1339693295U, 876U, 3887776532U },
|
|
{ 1545556285U, 961U, 1615538833U },
|
|
{ 601730776U, 723U, 1776162651U },
|
|
{ 1027516047U, 687U, 511983079U },
|
|
{ 416526298U, 700U, 916156552U },
|
|
{ 1395522032U, 652U, 2222063676U },
|
|
{ 366221443U, 617U, 2992857763U },
|
|
{ 1539836965U, 714U, 3783265725U },
|
|
{ 556206671U, 994U, 799626459U },
|
|
{ 684907218U, 799U, 367789491U },
|
|
{ 2121230701U, 931U, 2115467001U },
|
|
{ 1668516451U, 644U, 3620590685U },
|
|
{ 768046066U, 883U, 2034077390U },
|
|
{ 1989159136U, 833U, 1195767305U },
|
|
{ 536585145U, 996U, 3577259204U },
|
|
{ 1008129373U, 642U, 1478080776U },
|
|
{ 1740775604U, 939U, 1264980372U },
|
|
{ 1967883163U, 508U, 10734624U },
|
|
{ 1923019697U, 730U, 3821419629U },
|
|
{ 442079932U, 560U, 3440032343U },
|
|
{ 1961302714U, 845U, 841962572U },
|
|
{ 2030205964U, 962U, 1325144227U },
|
|
{ 1160407529U, 507U, 240940858U },
|
|
{ 635482502U, 779U, 4200489746U },
|
|
{ 1252788931U, 699U, 867195434U },
|
|
{ 1961817131U, 719U, 668237657U },
|
|
{ 1071468216U, 983U, 917876630U },
|
|
{ 1281848367U, 932U, 1003100039U },
|
|
{ 582537119U, 780U, 1127273778U },
|
|
{ 1973672777U, 853U, 1071368872U },
|
|
{ 1896756996U, 762U, 1127851055U },
|
|
{ 847917054U, 500U, 1717499075U },
|
|
{ 1240520510U, 951U, 2849576657U },
|
|
{ 1685071682U, 567U, 1961810396U },
|
|
{ 1516232129U, 557U, 3173877U },
|
|
{ 1208118903U, 612U, 1613145022U },
|
|
{ 1817269927U, 693U, 4279122573U },
|
|
{ 1510091701U, 717U, 638191229U },
|
|
{ 365916850U, 807U, 600424314U },
|
|
{ 399324359U, 702U, 1803598116U },
|
|
{ 1318480274U, 779U, 2074237022U },
|
|
{ 697758115U, 840U, 1483639402U },
|
|
{ 1696507773U, 840U, 577415447U },
|
|
{ 2081979121U, 981U, 3041486449U },
|
|
{ 955646687U, 742U, 3846494357U },
|
|
{ 1250683506U, 749U, 836419859U },
|
|
{ 595003102U, 534U, 366794109U },
|
|
{ 47485338U, 558U, 3521120834U },
|
|
{ 619433479U, 610U, 3991783875U },
|
|
{ 704096520U, 518U, 4139493852U },
|
|
{ 1712224984U, 606U, 2393312003U },
|
|
{ 1318233152U, 922U, 3880361134U },
|
|
{ 855572992U, 761U, 1472974787U },
|
|
{ 64721421U, 703U, 683860550U },
|
|
{ 678931758U, 840U, 380616043U },
|
|
{ 692711973U, 778U, 1382361947U },
|
|
{ 677703619U, 530U, 2826914161U },
|
|
{ 92393223U, 586U, 1522128471U },
|
|
{ 1222592920U, 743U, 3466726667U },
|
|
{ 358288986U, 695U, 1091956998U },
|
|
{ 1935056945U, 958U, 514864477U },
|
|
{ 735675993U, 990U, 1294239989U },
|
|
{ 1560089402U, 897U, 2238551287U },
|
|
{ 70616361U, 829U, 22483098U },
|
|
{ 368234700U, 731U, 2913875084U },
|
|
{ 20221190U, 879U, 1564152970U },
|
|
{ 539444654U, 682U, 1835141259U },
|
|
{ 1314987297U, 840U, 1801114136U },
|
|
{ 2019295544U, 645U, 3286438930U },
|
|
{ 469023838U, 716U, 1637918202U },
|
|
{ 1843754496U, 653U, 2562092152U },
|
|
{ 400672036U, 809U, 4264212785U },
|
|
{ 404722249U, 965U, 2704116999U },
|
|
{ 600702209U, 758U, 584979986U },
|
|
{ 519953954U, 667U, 2574436237U },
|
|
{ 1658071126U, 694U, 2214569490U },
|
|
{ 420480037U, 749U, 3430010866U },
|
|
{ 690103647U, 969U, 3700758083U },
|
|
{ 1029424799U, 937U, 3787746841U },
|
|
{ 2012608669U, 506U, 3362628973U },
|
|
{ 1535432887U, 998U, 42610943U },
|
|
{ 1330635533U, 857U, 3040806504U },
|
|
{ 1223800550U, 539U, 3954229517U },
|
|
{ 1322411537U, 680U, 3223250324U },
|
|
{ 1877847898U, 945U, 2915147143U },
|
|
{ 1646356099U, 874U, 965988280U },
|
|
{ 805687536U, 744U, 4032277920U },
|
|
{ 1948093210U, 633U, 1346597684U },
|
|
{ 392609744U, 783U, 1636083295U },
|
|
{ 690241304U, 770U, 1201031298U },
|
|
{ 1360302965U, 696U, 1665394461U },
|
|
{ 1220090946U, 780U, 1316922812U },
|
|
{ 447092251U, 500U, 3438743375U },
|
|
{ 1613868791U, 592U, 828546883U },
|
|
{ 523430951U, 548U, 2552392304U },
|
|
{ 726692899U, 810U, 1656872867U },
|
|
{ 1364340021U, 836U, 3710513486U },
|
|
{ 1986257729U, 931U, 935013962U },
|
|
{ 407983964U, 921U, 728767059U },
|
|
};
|
|
|
|
static void __init prandom_state_selftest(void)
|
|
{
|
|
int i, j, errors = 0, runs = 0;
|
|
bool error = false;
|
|
|
|
for (i = 0; i < ARRAY_SIZE(test1); i++) {
|
|
struct rnd_state state;
|
|
|
|
prandom_seed_early(&state, test1[i].seed, false);
|
|
prandom_warmup(&state);
|
|
|
|
if (test1[i].result != prandom_u32_state(&state))
|
|
error = true;
|
|
}
|
|
|
|
if (error)
|
|
pr_warn("prandom: seed boundary self test failed\n");
|
|
else
|
|
pr_info("prandom: seed boundary self test passed\n");
|
|
|
|
for (i = 0; i < ARRAY_SIZE(test2); i++) {
|
|
struct rnd_state state;
|
|
|
|
prandom_seed_early(&state, test2[i].seed, false);
|
|
prandom_warmup(&state);
|
|
|
|
for (j = 0; j < test2[i].iteration - 1; j++)
|
|
prandom_u32_state(&state);
|
|
|
|
if (test2[i].result != prandom_u32_state(&state))
|
|
errors++;
|
|
|
|
runs++;
|
|
cond_resched();
|
|
}
|
|
|
|
if (errors)
|
|
pr_warn("prandom: %d/%d self tests failed\n", errors, runs);
|
|
else
|
|
pr_info("prandom: %d self tests passed\n", runs);
|
|
}
|
|
#endif
|