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Commit 75ecab1d authored by David S. Miller's avatar David S. Miller
Browse files

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: default avatarDavid S. Miller <davem@davemloft.net>
parents 12959667 a6a9c0f1

drivers/char/random.c

+4 −1
Original line number Diff line number Diff line
@@ -603,8 +603,11 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits) 


	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,

include/linux/random.h

+10 −4
Original line number Diff line number Diff line
@@ -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

include/uapi/linux/random.h

+0 −7
Original line number Diff line number Diff line
@@ -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 */

lib/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -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

#

lib/random32.c

+273 −34
Original line number Diff line number Diff line
@@ -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