Merge branch 'prandom'

prandom fixes/improvements

====================
It would be great if you could still consider this series that fixes and
improves prandom for 3.13. We have sent it to netdev as prandom() originally
came from net/core/utils.c and networking is its main user. For a detailled
description, please see individual patches.

For patch 3 in this series, there will be a minor merge conflict with the
random tree that is for 3.13. See below how to resolve it.

====
Hannes says: on merge with the random tree I would suggest to resolve the
conflict in drivers/char/random.c like this:

if (r->entropy_total > 128) {
	r->initialized = 1;
	r->entropy_total = 0;
	if (r == &nonblocking_pool) {
		prandom_reseed_late();
		pr_notice("random: %s pool is initialized\n",
			  r->name);
	}
}

So it won't generate a warning if DEBUG_RANDOM_BOOT gets activated.
====

Patch 1 should probably also go to -stable.

Set tested on 32 and 64 bit machines.

Thanks a lot!

Ref. original discussion: http://patchwork.ozlabs.org/patch/289951/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 294 insertions, 46 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 7a744d391756..4fe5609eeb72 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -603,8 +603,11 @@ retry:
 
         if (!r->initialized && nbits > 0) {
                 r->entropy_total += nbits;
-                if (r->entropy_total > 128)
+                if (r->entropy_total > 128) {
                         r->initialized = 1;
+                        if (r == &nonblocking_pool)
+                                prandom_reseed_late();
+                }
         }
 
         trace_credit_entropy_bits(r->name, nbits, entropy_count,
diff --git a/include/linux/random.h b/include/linux/random.h
index 6312dd9ba449..4002b3df4c85 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -29,8 +29,13 @@ unsigned long randomize_range(unsigned long start, unsigned long end, unsigned l
 u32 prandom_u32(void);
 void prandom_bytes(void *buf, int nbytes);
 void prandom_seed(u32 seed);
+void prandom_reseed_late(void);
 
-u32 prandom_u32_state(struct rnd_state *);
+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, int nbytes);
 
 /*
@@ -50,9 +55,10 @@ static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
 {
         u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
 
-        state->s1 = __seed(i, 1);
-        state->s2 = __seed(i, 7);
-        state->s3 = __seed(i, 15);
+        state->s1 = __seed(i,   2U);
+        state->s2 = __seed(i,   8U);
+        state->s3 = __seed(i,  16U);
+        state->s4 = __seed(i, 128U);
 }
 
 #ifdef CONFIG_ARCH_RANDOM
diff --git a/include/uapi/linux/random.h b/include/uapi/linux/random.h
index 7471b5b3b8ba..fff3528a078f 100644
--- a/include/uapi/linux/random.h
+++ b/include/uapi/linux/random.h
@@ -40,11 +40,4 @@ struct rand_pool_info {
         __u32   buf[0];
 };
 
-struct rnd_state {
-        __u32 s1, s2, s3;
-};
-
-/* Exported functions */
-
-
 #endif /* _UAPI_LINUX_RANDOM_H */
diff --git a/lib/Kconfig b/lib/Kconfig
index b3c8be0da17f..75485e163ca3 100644
--- 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 52280d5526be..82da4f4c3489 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