random32: add test cases for taus113 implementation

We generated a battery of 100 test cases from GSL taus113 implemention
and compare the results from a particular seed and a particular
iteration with our implementation in the kernel. We have verified on
32 and 64 bit machines that our taus113 kernel implementation gives
same results as GSL taus113 implementation:

  [    0.147370] prandom: seed boundary self test passed
  [    0.148078] prandom: 100 self tests passed

This is a Kconfig option that is disabled on default, just like the
crc32 init selftests in order to not unnecessary slow down boot process.
We also refactored out prandom_seed_very_weak() as it's now used in
multiple places in order to reduce redundant code.

GSL code we used for generating test cases:

  int i, j;
  srand(time(NULL));
  for (i = 0; i < 100; ++i) {
    int iteration = 500 + (rand() % 500);
    gsl_rng_default_seed = rand() + 1;
    gsl_rng *r = gsl_rng_alloc(gsl_rng_taus113);
    printf("\t{ %lu, ", gsl_rng_default_seed);
    for (j = 0; j < iteration - 1; ++j)
      gsl_rng_get(r);
    printf("%u, %lu },\n", iteration, gsl_rng_get(r));
    gsl_rng_free(r);
  }

Joint work with Hannes Frederic Sowa.

Cc: Florian Weimer <fweimer@redhat.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/lib/Kconfig b/lib/Kconfig
index b3c8be0da17f8472429ad79787c76d42fa62eb02..75485e163ca3bc8e807c10f7fdf2c761a7df377f 100644 (file)
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -189,6 +189,13 @@ config AUDIT_GENERIC
        depends on AUDIT && !AUDIT_ARCH
        default y
 
+config RANDOM32_SELFTEST
+       bool "PRNG perform self test on init"
+       default n
+       help
+         This option enables the 32 bit PRNG library functions to perform a
+         self test on initialization.
+
 #
 # compression support is select'ed if needed
 #

diff --git a/lib/random32.c b/lib/random32.c
index 27adb753180f3b5438d65de23157a265e9e12b4b..82da4f4c3489eb0fa2a814adf477be16c14cbed4 100644 (file)
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -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);
 
@@ -142,6 +147,23 @@ static void prandom_warmup(struct rnd_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
@@ -172,15 +194,14 @@ 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) * 69069U)  /* super-duper LCG */
-               state->s1 = __seed(LCG((i + jiffies) ^ random_get_entropy()), 2U);
-               state->s2 = __seed(LCG(state->s1),   8U);
-               state->s3 = __seed(LCG(state->s2),  16U);
-               state->s4 = __seed(LCG(state->s3), 128U);
-
+               prandom_seed_very_weak(state, (i + jiffies) ^ random_get_entropy());
                prandom_warmup(state);
        }
        return 0;
@@ -253,3 +274,165 @@ static int __init prandom_reseed(void)
        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