kernel-ark/lib/random32.c
Linus Torvalds 9ffc66941d This adds a new gcc plugin named "latent_entropy". It is designed to
extract as much possible uncertainty from a running system at boot time as
 possible, hoping to capitalize on any possible variation in CPU operation
 (due to runtime data differences, hardware differences, SMP ordering,
 thermal timing variation, cache behavior, etc).
 
 At the very least, this plugin is a much more comprehensive example for
 how to manipulate kernel code using the gcc plugin internals.
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Merge tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull gcc plugins update from Kees Cook:
 "This adds a new gcc plugin named "latent_entropy". It is designed to
  extract as much possible uncertainty from a running system at boot
  time as possible, hoping to capitalize on any possible variation in
  CPU operation (due to runtime data differences, hardware differences,
  SMP ordering, thermal timing variation, cache behavior, etc).

  At the very least, this plugin is a much more comprehensive example
  for how to manipulate kernel code using the gcc plugin internals"

* tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  latent_entropy: Mark functions with __latent_entropy
  gcc-plugins: Add latent_entropy plugin
2016-10-15 10:03:15 -07:00

465 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) __latent_entropy;
/**
* 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(net_rand_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(net_rand_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)
{
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);
}
}
EXPORT_SYMBOL(prandom_seed_full_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