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/*-
* Copyright (c) 2000 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.
*
* $FreeBSD$
*/
/* NOTE NOTE NOTE - This is not finished! It will supply numbers, but
* it is not yet cryptographically secure!!
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/queue.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/linker.h>
#include <sys/libkern.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/proc.h>
#include <sys/random.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/unistd.h>
#include <machine/mutex.h>
#include <crypto/blowfish/blowfish.h>
#include <dev/randomdev/hash.h>
#include <dev/randomdev/yarrow.h>
/* #define DEBUG */
/* #define DEBUG1 */ /* Very noisy - prints plenty harvesting stats */
static void generator_gate(void);
static void reseed(int);
static void random_harvest_internal(struct timespec *, void *, u_int, u_int, u_int, enum esource);
static void random_kthread(void *);
/* Structure holding the entropy state */
struct random_state random_state;
/* Queue holding harvested entropy */
TAILQ_HEAD(harvestqueue, harvest) harvestqueue,
initqueue = TAILQ_HEAD_INITIALIZER(harvestqueue);
/* These are used to queue harvested packets of entropy. The entropy
* buffer size of 16 is pretty arbitrary.
*/
struct harvest {
struct timespec time; /* nanotime for clock jitter */
u_char entropy[16]; /* the harvested entropy */
u_int size, bits, frac; /* stats about the entropy */
enum esource source; /* stats about the entropy */
u_int pool; /* which pool this goes into */
TAILQ_ENTRY(harvest) harvest; /* link to next */
};
/* The reseed thread mutex */
static mtx_t random_reseed_mtx;
/* The entropy harvest mutex */
static mtx_t random_harvest_mtx;
/* <0 until the kthread starts, 0 for running */
static int random_kthread_status = -1;
/* <0 to end the kthread, 0 to let it run */
static int random_kthread_control = 0;
static struct proc *random_kthread_proc;
static void
random_kthread(void *status)
{
int pl, src, overthreshhold[2];
struct harvest *event;
struct source *source;
#ifdef DEBUG1
int queuecount;
#endif
#ifdef DEBUG
printf("At %s, line %d: mtx_owned(&Giant) == %d\n", __FILE__, __LINE__, mtx_owned(&Giant));
printf("At %s, line %d: mtx_owned(&sched_lock) == %d\n", __FILE__, __LINE__, mtx_owned(&sched_lock));
#endif
random_set_wakeup((int *)status, 0);
for (pl = 0; pl < 2; pl++)
yarrow_hash_init(&random_state.pool[pl].hash, NULL, 0);
for (;;) {
if (TAILQ_EMPTY(&harvestqueue)) {
/* Sleep for a second to give the system a chance */
mtx_enter(&Giant, MTX_DEF);
tsleep(&harvestqueue, PUSER, "rndslp", hz);
mtx_exit(&Giant, MTX_DEF);
}
else {
/* Suck the harvested entropy out of the queue and hash
* it into the fast and slow pools.
*/
#ifdef DEBUG1
queuecount = 0;
#endif
while (!TAILQ_EMPTY(&harvestqueue)) {
#ifdef DEBUG1
queuecount++;
#endif
mtx_enter(&random_harvest_mtx, MTX_DEF);
event = TAILQ_FIRST(&harvestqueue);
TAILQ_REMOVE(&harvestqueue, event, harvest);
mtx_exit(&random_harvest_mtx, MTX_DEF);
source = &random_state.pool[event->pool].source[event->source];
yarrow_hash_iterate(&random_state.pool[event->pool].hash,
event->entropy, sizeof(event->entropy));
yarrow_hash_iterate(&random_state.pool[event->pool].hash,
&event->time, sizeof(event->time));
source->frac += event->frac;
source->bits += event->bits + source->frac/1024;
source->frac %= 1024;
free(event, M_TEMP);
/* XXX abuse tsleep() to get at mi_switch() */
/* tsleep(&harvestqueue, PUSER, "rndprc", 1); */
}
#ifdef DEBUG1
printf("Harvested %d events\n", queuecount);
#endif
/* Count the over-threshold sources in each pool */
for (pl = 0; pl < 2; pl++) {
overthreshhold[pl] = 0;
for (src = 0; 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);
}
/* Is the thread scheduled for a shutdown? */
if (random_kthread_control < 0) {
if (!TAILQ_EMPTY(&harvestqueue)) {
#ifdef DEBUG
printf("Random cleaning extraneous events\n");
#endif
mtx_enter(&random_harvest_mtx, MTX_DEF);
TAILQ_FOREACH(event, &harvestqueue, harvest) {
TAILQ_REMOVE(&harvestqueue, event, harvest);
free(event, M_TEMP);
}
mtx_exit(&random_harvest_mtx, MTX_DEF);
}
#ifdef DEBUG
printf("Random kthread setting terminate\n");
#endif
random_set_wakeup_exit((int *)status, -1, 0);
break;
}
}
}
int
random_init(void)
{
int error;
#ifdef DEBUG
printf("Random initialise\n");
#endif
random_state.gengateinterval = 10;
random_state.bins = 10;
random_state.pool[0].thresh = 100;
random_state.pool[1].thresh = 160;
random_state.slowoverthresh = 2;
random_state.which = FAST;
harvestqueue = initqueue;
/* Initialise the mutexes */
mtx_init(&random_reseed_mtx, "random reseed", MTX_DEF);
mtx_init(&random_harvest_mtx, "random harvest", MTX_DEF);
/* Start the hash/reseed thread */
error = kthread_create(random_kthread, &random_kthread_status,
&random_kthread_proc, RFHIGHPID, "random");
if (error != 0)
return error;
/* Register the randomness harvesting routine */
random_init_harvester(random_harvest_internal);
#ifdef DEBUG
printf("Random initalise finish\n");
#endif
return 0;
}
void
random_deinit(void)
{
#ifdef DEBUG
printf("Random deinitalise\n");
#endif
/* Deregister the randomness harvesting routine */
random_deinit_harvester();
#ifdef DEBUG
printf("Random deinitalise waiting for thread to terminate\n");
#endif
/* Command the hash/reseed thread to end and wait for it to finish */
random_kthread_control = -1;
while (random_kthread_status != -1)
tsleep(&random_kthread_status, PUSER, "rndend", hz);
#ifdef DEBUG
printf("Random deinitalise removing mutexes\n");
#endif
/* Remove the mutexes */
mtx_destroy(&random_reseed_mtx);
mtx_destroy(&random_harvest_mtx);
#ifdef DEBUG
printf("Random deinitalise finish\n");
#endif
}
static void
reseed(int fastslow)
{
/* Interrupt-context stack is a limited resource; make large
* structures static.
*/
static u_char v[TIMEBIN][KEYSIZE]; /* v[i] */
static struct yarrowhash context;
u_char hash[KEYSIZE]; /* h' */
u_char temp[KEYSIZE];
int i, j;
#ifdef DEBUG
printf("Reseed type %d\n", fastslow);
#endif
/* The reseed task must not be jumped on */
mtx_enter(&random_reseed_mtx, MTX_DEF);
/* 1. Hash the accumulated entropy into v[0] */
yarrow_hash_init(&context, NULL, 0);
/* Feed the slow pool hash in if slow */
if (fastslow == SLOW)
yarrow_hash_iterate(&context,
&random_state.pool[SLOW].hash, sizeof(struct yarrowhash));
yarrow_hash_iterate(&context,
&random_state.pool[FAST].hash, sizeof(struct yarrowhash));
/* 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++) {
yarrow_hash_init(&context, NULL, 0);
/* v[i] #= h(v[i-1]) */
yarrow_hash_iterate(&context, v[i - 1], KEYSIZE);
/* v[i] #= h(v[0]) */
yarrow_hash_iterate(&context, v[0], KEYSIZE);
/* v[i] #= h(i) */
yarrow_hash_iterate(&context, &i, sizeof(int));
/* Return the hashval */
yarrow_hash_finish(&context, v[i]);
}
/* 3. Compute a new key; h' is the identity function here;
* it is not being ignored!
*/
yarrow_hash_init(&context, NULL, 0);
yarrow_hash_iterate(&context, &random_state.key, KEYSIZE);
for (i = 1; i < random_state.bins; i++)
yarrow_hash_iterate(&context, &v[i], KEYSIZE);
yarrow_hash_finish(&context, temp);
yarrow_encrypt_init(&random_state.key, temp, KEYSIZE);
/* 4. Recompute the counter */
random_state.counter = 0;
yarrow_encrypt(&random_state.key, &random_state.counter, temp,
sizeof(random_state.counter));
memcpy(&random_state.counter, temp, random_state.counter);
/* 5. Reset entropy estimate accumulators to zero */
for (i = 0; i <= fastslow; i++) {
for (j = 0; j < ENTROPYSOURCE; j++) {
if (random_state.pool[i].source[j].bits >
random_state.pool[i].thresh) {
random_state.pool[i].source[j].bits = 0;
random_state.pool[i].source[j].frac = 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 */
/* Release the reseed mutex */
mtx_exit(&random_reseed_mtx, MTX_DEF);
#ifdef DEBUG
printf("Reseed finish\n");
#endif
}
u_int
read_random(void *buf, u_int count)
{
static u_int64_t genval;
static int cur = 0;
static int gate = 1;
u_int i;
u_int retval;
/* The reseed task must not be jumped on */
mtx_enter(&random_reseed_mtx, MTX_DEF);
if (gate) {
generator_gate();
random_state.outputblocks = 0;
gate = 0;
}
if (count >= sizeof(random_state.counter)) {
retval = 0;
for (i = 0; i < count; i += sizeof(random_state.counter)) {
random_state.counter++;
yarrow_encrypt(&random_state.key, &random_state.counter,
&genval, sizeof(random_state.counter));
memcpy((char *)buf + i, &genval,
sizeof(random_state.counter));
if (++random_state.outputblocks >= random_state.gengateinterval) {
generator_gate();
random_state.outputblocks = 0;
}
retval += sizeof(random_state.counter);
}
}
else {
if (!cur) {
random_state.counter++;
yarrow_encrypt(&random_state.key, &random_state.counter,
&genval, sizeof(random_state.counter));
memcpy(buf, &genval, count);
cur = sizeof(random_state.counter) - count;
if (++random_state.outputblocks >= random_state.gengateinterval) {
generator_gate();
random_state.outputblocks = 0;
}
retval = count;
}
else {
retval = cur < count ? cur : count;
memcpy(buf,
(char *)&genval +
(sizeof(random_state.counter) - cur),
retval);
cur -= retval;
}
}
mtx_exit(&random_reseed_mtx, MTX_DEF);
return retval;
}
void
write_random(void *buf, u_int count)
{
u_int i;
struct timespec timebuf;
/* arbitrarily break the input up into 8-byte chunks */
for (i = 0; i < count; i += 8) {
nanotime(&timebuf);
random_harvest_internal(&timebuf, (char *)buf + i, 8, 0, 0,
RANDOM_WRITE);
}
/* Maybe the loop iterated at least once */
if (i > count)
i -= 8;
/* Get the last bytes even if the input length is not a multiple of 8 */
count %= 8;
if (count) {
nanotime(&timebuf);
random_harvest_internal(&timebuf, (char *)buf + i, count, 0, 0,
RANDOM_WRITE);
}
/* Explicit reseed */
reseed(FAST);
}
static void
generator_gate(void)
{
int i;
u_char temp[KEYSIZE];
#ifdef DEBUG
printf("Generator gate\n");
#endif
for (i = 0; i < KEYSIZE; i += sizeof(random_state.counter)) {
random_state.counter++;
yarrow_encrypt(&random_state.key, &random_state.counter,
&(temp[i]), sizeof(random_state.counter));
}
yarrow_encrypt_init(&random_state.key, temp, KEYSIZE);
memset((void *)temp, 0, KEYSIZE);
#ifdef DEBUG
printf("Generator gate finish\n");
#endif
}
/* Entropy harvesting routine. This is supposed to be fast; do
* not do anything slow in here!
*/
static void
random_harvest_internal(struct timespec *timep, void *entropy, u_int count,
u_int bits, u_int frac, enum esource origin)
{
struct harvest *event;
u_int64_t entropy_buf;
#if 0
#ifdef DEBUG
printf("Random harvest\n");
#endif
#endif
event = malloc(sizeof(struct harvest), M_TEMP, M_NOWAIT);
if (origin < ENTROPYSOURCE && event != NULL) {
/* nanotime provides clock jitter */
event->time = *timep;
/* the harvested entropy */
count = count > sizeof(entropy_buf)
? sizeof(entropy_buf)
: count;
memcpy(event->entropy, entropy, count);
event->size = count;
event->bits = bits;
event->frac = frac;
event->source = origin;
/* protect the queue from simultaneous updates */
mtx_enter(&random_harvest_mtx, MTX_DEF);
/* toggle the pool for next insertion */
event->pool = random_state.which;
random_state.which = !random_state.which;
TAILQ_INSERT_TAIL(&harvestqueue, event, harvest);
mtx_exit(&random_harvest_mtx, MTX_DEF);
}
}
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