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/*-
* Copyright (c) 2000-2013 Mark R V Murray
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer
* in this position and unchanged.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/random.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <crypto/rijndael/rijndael-api-fst.h>
#include <crypto/sha2/sha2.h>
#include <dev/random/hash.h>
#include <dev/random/random_adaptors.h>
#include <dev/random/randomdev_soft.h>
#include <dev/random/yarrow.h>
#define TIMEBIN 16 /* max value for Pt/t */
#define FAST 0
#define SLOW 1
/* This is the beastie that needs protecting. It contains all of the
* state that we are excited about.
* Exactly one is instantiated.
*/
static struct random_state {
union {
uint8_t byte[BLOCKSIZE];
uint64_t qword[BLOCKSIZE/sizeof(uint64_t)];
} counter; /* C */
struct randomdev_key key; /* K */
u_int gengateinterval; /* Pg */
u_int bins; /* Pt/t */
u_int outputblocks; /* count output blocks for gates */
u_int slowoverthresh; /* slow pool overthreshhold reseed count */
struct pool {
struct source {
u_int bits; /* estimated bits of entropy */
} source[ENTROPYSOURCE];
u_int thresh; /* pool reseed threshhold */
struct randomdev_hash hash; /* accumulated entropy */
} pool[2]; /* pool[0] is fast, pool[1] is slow */
u_int which; /* toggle - sets the current insertion pool */
} random_state;
RANDOM_CHECK_UINT(gengateinterval, 4, 64);
RANDOM_CHECK_UINT(bins, 2, 16);
RANDOM_CHECK_UINT(fastthresh, (BLOCKSIZE*8)/4, (BLOCKSIZE*8)); /* Bit counts */
RANDOM_CHECK_UINT(slowthresh, (BLOCKSIZE*8)/4, (BLOCKSIZE*8)); /* Bit counts */
RANDOM_CHECK_UINT(slowoverthresh, 1, 5);
static void generator_gate(void);
static void reseed(u_int);
/* The reseed thread mutex */
struct mtx random_reseed_mtx;
/* 128-bit C = 0 */
/* Nothing to see here, folks, just an ugly mess. */
static void
clear_counter(void)
{
random_state.counter.qword[0] = 0UL;
random_state.counter.qword[1] = 0UL;
}
/* 128-bit C = C + 1 */
/* Nothing to see here, folks, just an ugly mess. */
/* TODO: Make a Galois counter instead? */
static void
increment_counter(void)
{
random_state.counter.qword[0]++;
if (!random_state.counter.qword[0])
random_state.counter.qword[1]++;
}
/* Process a single stochastic event off the harvest queue */
void
random_process_event(struct harvest *event)
{
u_int pl, overthreshhold[2];
struct source *source;
enum esource src;
#if 0
/* Do this better with DTrace */
{
int i;
printf("Harvest:%16jX ", event->somecounter);
for (i = 0; i < event->size; i++)
printf("%02X", event->entropy[i]);
for (; i < 16; i++)
printf(" ");
printf(" %2d %2d %02X\n", event->size, event->bits, event->source);
}
#endif
/* Accumulate the event into the appropriate pool */
pl = random_state.which;
source = &random_state.pool[pl].source[event->source];
randomdev_hash_iterate(&random_state.pool[pl].hash, event,
sizeof(*event));
source->bits += event->bits;
/* Count the over-threshold sources in each pool */
for (pl = 0; pl < 2; pl++) {
overthreshhold[pl] = 0;
for (src = RANDOM_START; src < ENTROPYSOURCE; src++) {
if (random_state.pool[pl].source[src].bits
> random_state.pool[pl].thresh)
overthreshhold[pl]++;
}
}
/* if any fast source over threshhold, reseed */
if (overthreshhold[FAST])
reseed(FAST);
/* if enough slow sources are over threshhold, reseed */
if (overthreshhold[SLOW] >= random_state.slowoverthresh)
reseed(SLOW);
/* Invert the fast/slow pool selector bit */
random_state.which = !random_state.which;
}
void
random_yarrow_init_alg(struct sysctl_ctx_list *clist)
{
int i;
struct sysctl_oid *random_yarrow_o;
/* Yarrow parameters. Do not adjust these unless you have
* have a very good clue about what they do!
*/
random_yarrow_o = SYSCTL_ADD_NODE(clist,
SYSCTL_STATIC_CHILDREN(_kern_random),
OID_AUTO, "yarrow", CTLFLAG_RW, 0,
"Yarrow Parameters");
SYSCTL_ADD_PROC(clist,
SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
"gengateinterval", CTLTYPE_INT|CTLFLAG_RW,
&random_state.gengateinterval, 10,
random_check_uint_gengateinterval, "I",
"Generation gate interval");
SYSCTL_ADD_PROC(clist,
SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
"bins", CTLTYPE_INT|CTLFLAG_RW,
&random_state.bins, 10,
random_check_uint_bins, "I",
"Execution time tuner");
SYSCTL_ADD_PROC(clist,
SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
"fastthresh", CTLTYPE_INT|CTLFLAG_RW,
&random_state.pool[0].thresh, (3*(BLOCKSIZE*8))/4,
random_check_uint_fastthresh, "I",
"Fast reseed threshold");
SYSCTL_ADD_PROC(clist,
SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
"slowthresh", CTLTYPE_INT|CTLFLAG_RW,
&random_state.pool[1].thresh, (BLOCKSIZE*8),
random_check_uint_slowthresh, "I",
"Slow reseed threshold");
SYSCTL_ADD_PROC(clist,
SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
"slowoverthresh", CTLTYPE_INT|CTLFLAG_RW,
&random_state.slowoverthresh, 2,
random_check_uint_slowoverthresh, "I",
"Slow over-threshold reseed");
random_state.gengateinterval = 10;
random_state.bins = 10;
random_state.pool[0].thresh = (3*(BLOCKSIZE*8))/4;
random_state.pool[1].thresh = (BLOCKSIZE*8);
random_state.slowoverthresh = 2;
random_state.which = FAST;
/* Initialise the fast and slow entropy pools */
for (i = 0; i < 2; i++)
randomdev_hash_init(&random_state.pool[i].hash);
/* Clear the counter */
clear_counter();
/* Set up a lock for the reseed process */
mtx_init(&random_reseed_mtx, "Yarrow reseed", NULL, MTX_DEF);
}
void
random_yarrow_deinit_alg(void)
{
mtx_destroy(&random_reseed_mtx);
}
static void
reseed(u_int fastslow)
{
/* Interrupt-context stack is a limited resource; make large
* structures static.
*/
static uint8_t v[TIMEBIN][KEYSIZE]; /* v[i] */
static struct randomdev_hash context;
uint8_t hash[KEYSIZE]; /* h' */
uint8_t temp[KEYSIZE];
u_int i;
enum esource j;
#if 0
printf("Yarrow: %s reseed\n", fastslow == FAST ? "fast" : "slow");
#endif
/* The reseed task must not be jumped on */
mtx_lock(&random_reseed_mtx);
/* 1. Hash the accumulated entropy into v[0] */
randomdev_hash_init(&context);
/* Feed the slow pool hash in if slow */
if (fastslow == SLOW)
randomdev_hash_iterate(&context,
&random_state.pool[SLOW].hash,
sizeof(struct randomdev_hash));
randomdev_hash_iterate(&context,
&random_state.pool[FAST].hash, sizeof(struct randomdev_hash));
randomdev_hash_finish(&context, v[0]);
/* 2. Compute hash values for all v. _Supposed_ to be computationally
* intensive.
*/
if (random_state.bins > TIMEBIN)
random_state.bins = TIMEBIN;
for (i = 1; i < random_state.bins; i++) {
randomdev_hash_init(&context);
/* v[i] #= h(v[i - 1]) */
randomdev_hash_iterate(&context, v[i - 1], KEYSIZE);
/* v[i] #= h(v[0]) */
randomdev_hash_iterate(&context, v[0], KEYSIZE);
/* v[i] #= h(i) */
randomdev_hash_iterate(&context, &i, sizeof(u_int));
/* Return the hashval */
randomdev_hash_finish(&context, v[i]);
}
/* 3. Compute a new key; h' is the identity function here;
* it is not being ignored!
*/
randomdev_hash_init(&context);
randomdev_hash_iterate(&context, &random_state.key, KEYSIZE);
for (i = 1; i < random_state.bins; i++)
randomdev_hash_iterate(&context, &v[i], KEYSIZE);
randomdev_hash_finish(&context, temp);
randomdev_encrypt_init(&random_state.key, temp);
/* 4. Recompute the counter */
clear_counter();
randomdev_encrypt(&random_state.key, random_state.counter.byte, temp, BLOCKSIZE);
memcpy(random_state.counter.byte, temp, BLOCKSIZE);
/* 5. Reset entropy estimate accumulators to zero */
for (i = 0; i <= fastslow; i++)
for (j = RANDOM_START; j < ENTROPYSOURCE; j++)
random_state.pool[i].source[j].bits = 0;
/* 6. Wipe memory of intermediate values */
memset((void *)v, 0, sizeof(v));
memset((void *)temp, 0, sizeof(temp));
memset((void *)hash, 0, sizeof(hash));
/* 7. Dump to seed file */
/* XXX Not done here yet */
/* Unblock the device if it was blocked due to being unseeded */
randomdev_unblock();
/* Release the reseed mutex */
mtx_unlock(&random_reseed_mtx);
}
/* Internal function to return processed entropy from the PRNG */
int
random_yarrow_read(void *buf, int count)
{
static int cur = 0;
static int gate = 1;
static uint8_t genval[KEYSIZE];
size_t tomove;
int i;
int retval;
/* Check for final read request */
if (buf == NULL && count == 0)
return (0);
/* The reseed task must not be jumped on */
mtx_lock(&random_reseed_mtx);
if (gate) {
generator_gate();
random_state.outputblocks = 0;
gate = 0;
}
if (count > 0 && (size_t)count >= BLOCKSIZE) {
retval = 0;
for (i = 0; i < count; i += BLOCKSIZE) {
increment_counter();
randomdev_encrypt(&random_state.key, random_state.counter.byte, genval, BLOCKSIZE);
tomove = MIN(count - i, BLOCKSIZE);
memcpy((char *)buf + i, genval, tomove);
if (++random_state.outputblocks >= random_state.gengateinterval) {
generator_gate();
random_state.outputblocks = 0;
}
retval += (int)tomove;
cur = 0;
}
}
else {
if (!cur) {
increment_counter();
randomdev_encrypt(&random_state.key, random_state.counter.byte, genval, BLOCKSIZE);
memcpy(buf, genval, (size_t)count);
cur = BLOCKSIZE - count;
if (++random_state.outputblocks >= random_state.gengateinterval) {
generator_gate();
random_state.outputblocks = 0;
}
retval = count;
}
else {
retval = MIN(cur, count);
memcpy(buf, &genval[BLOCKSIZE - cur], (size_t)retval);
cur -= retval;
}
}
mtx_unlock(&random_reseed_mtx);
return (retval);
}
static void
generator_gate(void)
{
u_int i;
uint8_t temp[KEYSIZE];
for (i = 0; i < KEYSIZE; i += BLOCKSIZE) {
increment_counter();
randomdev_encrypt(&random_state.key, random_state.counter.byte, temp + i, BLOCKSIZE);
}
randomdev_encrypt_init(&random_state.key, temp);
memset((void *)temp, 0, KEYSIZE);
}
/* Helper routine to perform explicit reseeds */
void
random_yarrow_reseed(void)
{
reseed(SLOW);
}
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