summaryrefslogtreecommitdiffstats
path: root/lib/random32.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/random32.c')
-rw-r--r--lib/random32.c307
1 files changed, 273 insertions, 34 deletions
diff --git a/lib/random32.c b/lib/random32.c
index 52280d5..82da4f4 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -2,19 +2,19 @@
This is a maximally equidistributed combined Tausworthe generator
based on code from GNU Scientific Library 1.5 (30 Jun 2004)
- x_n = (s1_n ^ s2_n ^ s3_n)
+ lfsr113 version:
- s1_{n+1} = (((s1_n & 4294967294) <<12) ^ (((s1_n <<13) ^ s1_n) >>19))
- s2_{n+1} = (((s2_n & 4294967288) << 4) ^ (((s2_n << 2) ^ s2_n) >>25))
- s3_{n+1} = (((s3_n & 4294967280) <<17) ^ (((s3_n << 3) ^ s3_n) >>11))
+ x_n = (s1_n ^ s2_n ^ s3_n ^ s4_n)
- The period of this generator is about 2^88.
+ 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))
- From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
- Generators", Mathematics of Computation, 65, 213 (1996), 203--213.
-
- This is available on the net from L'Ecuyer's home page,
+ 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
@@ -29,7 +29,7 @@
that paper.)
This affects the seeding procedure by imposing the requirement
- s1 > 1, s2 > 7, s3 > 15.
+ s1 > 1, s2 > 7, s3 > 15, s4 > 127.
*/
@@ -38,6 +38,11 @@
#include <linux/export.h>
#include <linux/jiffies.h>
#include <linux/random.h>
+#include <linux/sched.h>
+
+#ifdef CONFIG_RANDOM32_SELFTEST
+static void __init prandom_state_selftest(void);
+#endif
static DEFINE_PER_CPU(struct rnd_state, net_rand_state);
@@ -52,11 +57,12 @@ 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, 13, 19, 4294967294UL, 12);
- state->s2 = TAUSWORTHE(state->s2, 2, 25, 4294967288UL, 4);
- state->s3 = TAUSWORTHE(state->s3, 3, 11, 4294967280UL, 17);
+ 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);
+ return (state->s1 ^ state->s2 ^ state->s3 ^ state->s4);
}
EXPORT_SYMBOL(prandom_u32_state);
@@ -126,6 +132,38 @@ void prandom_bytes(void *buf, int bytes)
}
EXPORT_SYMBOL(prandom_bytes);
+static void prandom_warmup(struct rnd_state *state)
+{
+ /* Calling RNG ten times to satify 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 void prandom_seed_very_weak(struct rnd_state *state, u32 seed)
+{
+ /* Note: This sort of seeding is ONLY used in test cases and
+ * during boot at the time from core_initcall until late_initcall
+ * as we don't have a stronger entropy source available yet.
+ * After late_initcall, we reseed entire state, we have to (!),
+ * otherwise an attacker just needs to search 32 bit space to
+ * probe for our internal 128 bit state if he knows a couple
+ * of prandom32 outputs!
+ */
+#define LCG(x) ((x) * 69069U) /* super-duper LCG */
+ state->s1 = __seed(LCG(seed), 2U);
+ state->s2 = __seed(LCG(state->s1), 8U);
+ state->s3 = __seed(LCG(state->s2), 16U);
+ state->s4 = __seed(LCG(state->s3), 128U);
+}
+
/**
* prandom_seed - add entropy to pseudo random number generator
* @seed: seed value
@@ -141,7 +179,9 @@ void prandom_seed(u32 entropy)
*/
for_each_possible_cpu (i) {
struct rnd_state *state = &per_cpu(net_rand_state, i);
- state->s1 = __seed(state->s1 ^ entropy, 1);
+
+ state->s1 = __seed(state->s1 ^ entropy, 2U);
+ prandom_warmup(state);
}
}
EXPORT_SYMBOL(prandom_seed);
@@ -154,46 +194,245 @@ static int __init prandom_init(void)
{
int i;
+#ifdef CONFIG_RANDOM32_SELFTEST
+ prandom_state_selftest();
+#endif
+
for_each_possible_cpu(i) {
struct rnd_state *state = &per_cpu(net_rand_state,i);
-#define LCG(x) ((x) * 69069) /* super-duper LCG */
- state->s1 = __seed(LCG(i + jiffies), 1);
- state->s2 = __seed(LCG(state->s1), 7);
- state->s3 = __seed(LCG(state->s2), 15);
-
- /* "warm it up" */
- 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_seed_very_weak(state, (i + jiffies) ^ random_get_entropy());
+ 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;
+
+ get_random_bytes(&entropy, sizeof(entropy));
+ prandom_seed(entropy);
+ /* reseed every ~60 seconds, in [40 .. 80) interval with slack */
+ seed_timer.expires = jiffies + (40 * HZ + (prandom_u32() % (40 * HZ)));
+ add_timer(&seed_timer);
+}
+
+static void prandom_start_seed_timer(void)
+{
+ set_timer_slack(&seed_timer, HZ);
+ seed_timer.expires = jiffies + 40 * HZ;
+ add_timer(&seed_timer);
+}
+
/*
* Generate better values after random number generator
* is fully initialized.
*/
-static int __init prandom_reseed(void)
+static void __prandom_reseed(bool late)
{
int i;
+ unsigned long flags;
+ static bool latch = false;
+ static DEFINE_SPINLOCK(lock);
+
+ /* only allow initial seeding (late == false) once */
+ spin_lock_irqsave(&lock, flags);
+ if (latch && !late)
+ goto out;
+ latch = true;
for_each_possible_cpu(i) {
struct rnd_state *state = &per_cpu(net_rand_state,i);
- u32 seeds[3];
+ u32 seeds[4];
get_random_bytes(&seeds, sizeof(seeds));
- state->s1 = __seed(seeds[0], 1);
- state->s2 = __seed(seeds[1], 7);
- state->s3 = __seed(seeds[2], 15);
+ state->s1 = __seed(seeds[0], 2U);
+ state->s2 = __seed(seeds[1], 8U);
+ state->s3 = __seed(seeds[2], 16U);
+ state->s4 = __seed(seeds[3], 128U);
- /* mix it in */
- prandom_u32_state(state);
+ prandom_warmup(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_very_weak(&state, test1[i].seed);
+ 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_very_weak(&state, test2[i].seed);
+ 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
OpenPOWER on IntegriCloud