freebsd-dev/sys/dev/random/randomdev.c

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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.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/filio.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/poll.h>
#include <sys/proc.h>
#include <sys/random.h>
#include <sys/selinfo.h>
#include <sys/sysctl.h>
#include <sys/uio.h>
#include <sys/unistd.h>
#include <sys/vnode.h>
#include <machine/bus.h>
#include <machine/cpu.h>
#include <dev/random/randomdev.h>
static d_open_t random_open;
static d_close_t random_close;
static d_read_t random_read;
static d_write_t random_write;
static d_ioctl_t random_ioctl;
static d_poll_t random_poll;
#define CDEV_MAJOR 2
#define RANDOM_MINOR 3
static struct cdevsw random_cdevsw = {
/* open */ random_open,
/* close */ random_close,
/* read */ random_read,
/* write */ random_write,
/* ioctl */ random_ioctl,
/* poll */ random_poll,
/* mmap */ nommap,
/* strategy */ nostrategy,
/* name */ "random",
/* maj */ CDEV_MAJOR,
/* dump */ nodump,
/* psize */ nopsize,
/* flags */ 0,
/* kqfilter */ NULL
};
static void random_kthread(void *);
static void random_harvest_internal(u_int64_t, void *, u_int, u_int, u_int, enum esource);
static void random_write_internal(void *, int);
/* Ring buffer holding harvested entropy */
static struct harvestring {
volatile u_int head;
volatile u_int tail;
struct harvest data[HARVEST_RING_SIZE];
} harvestring;
static struct random_systat {
u_int seeded; /* 0 causes blocking 1 allows normal output */
u_int burst; /* number of events to do before sleeping */
struct selinfo rsel; /* For poll(2) */
} random_systat;
/* <0 to end the kthread, 0 to let it run */
static int random_kthread_control = 0;
static struct proc *random_kthread_proc;
/* For use with make_dev(9)/destroy_dev(9). */
static dev_t random_dev;
static dev_t urandom_dev;
/* ARGSUSED */
static int
random_check_boolean(SYSCTL_HANDLER_ARGS)
{
if (oidp->oid_arg1 != NULL && *(u_int *)(oidp->oid_arg1) != 0)
*(u_int *)(oidp->oid_arg1) = 1;
return sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
}
RANDOM_CHECK_UINT(burst, 0, 20);
SYSCTL_NODE(_kern, OID_AUTO, random, CTLFLAG_RW,
0, "Random Number Generator");
SYSCTL_NODE(_kern_random, OID_AUTO, sys, CTLFLAG_RW,
0, "Entropy Device Parameters");
SYSCTL_PROC(_kern_random_sys, OID_AUTO, seeded,
CTLTYPE_INT|CTLFLAG_RW, &random_systat.seeded, 1,
random_check_boolean, "I", "Seeded State");
SYSCTL_PROC(_kern_random_sys, OID_AUTO, burst,
CTLTYPE_INT|CTLFLAG_RW, &random_systat.burst, 20,
random_check_uint_burst, "I", "Harvest Burst Size");
SYSCTL_NODE(_kern_random_sys, OID_AUTO, harvest, CTLFLAG_RW,
0, "Entropy Sources");
SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, ethernet,
CTLTYPE_INT|CTLFLAG_RW, &harvest.ethernet, 0,
random_check_boolean, "I", "Harvest NIC entropy");
SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, point_to_point,
CTLTYPE_INT|CTLFLAG_RW, &harvest.point_to_point, 0,
random_check_boolean, "I", "Harvest serial net entropy");
SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, interrupt,
CTLTYPE_INT|CTLFLAG_RW, &harvest.interrupt, 0,
random_check_boolean, "I", "Harvest IRQ entropy");
SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, swi,
CTLTYPE_INT|CTLFLAG_RW, &harvest.swi, 0,
random_check_boolean, "I", "Harvest SWI entropy");
/* ARGSUSED */
static int
random_open(dev_t dev __unused, int flags, int fmt __unused, struct thread *td)
{
int error;
if (flags & FWRITE) {
error = suser(td);
if (error)
return (error);
error = securelevel_gt(td->td_ucred, 0);
if (error)
return (error);
}
return 0;
}
/* ARGSUSED */
static int
random_close(dev_t dev __unused, int flags, int fmt __unused, struct thread *td)
{
if (flags & FWRITE) {
if (!(suser(td) ||
securelevel_gt(td->td_ucred, 0)))
random_reseed();
}
return 0;
}
/* ARGSUSED */
static int
random_read(dev_t dev __unused, struct uio *uio, int flag)
{
int c, ret;
int error = 0;
void *random_buf;
while (!random_systat.seeded) {
if (flag & IO_NDELAY)
error = EWOULDBLOCK;
else
error = tsleep(&random_systat, PUSER|PCATCH,
"block", 0);
if (error != 0)
return error;
}
c = uio->uio_resid < PAGE_SIZE ? uio->uio_resid : PAGE_SIZE;
random_buf = (void *)malloc((u_long)c, M_TEMP, M_WAITOK);
while (uio->uio_resid > 0 && error == 0) {
ret = read_random_real(random_buf, c);
error = uiomove(random_buf, ret, uio);
}
free(random_buf, M_TEMP);
return error;
}
/* ARGSUSED */
static int
random_write(dev_t dev __unused, struct uio *uio, int flag __unused)
{
int c;
int error;
void *random_buf;
error = 0;
random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
while (uio->uio_resid > 0) {
c = (int)(uio->uio_resid < PAGE_SIZE
? uio->uio_resid
: PAGE_SIZE);
error = uiomove(random_buf, c, uio);
if (error)
break;
random_write_internal(random_buf, c);
}
free(random_buf, M_TEMP);
return error;
}
/* ARGSUSED */
static int
random_ioctl(dev_t dev __unused, u_long cmd, caddr_t addr __unused,
int flags __unused, struct thread *td __unused)
{
switch (cmd) {
/* Really handled in upper layer */
case FIOASYNC:
case FIONBIO:
return 0;
default:
return ENOTTY;
}
}
/* ARGSUSED */
static int
random_poll(dev_t dev __unused, int events, struct thread *td)
{
int revents;
revents = 0;
if (events & (POLLIN | POLLRDNORM)) {
if (random_systat.seeded)
revents = events & (POLLIN | POLLRDNORM);
else
selrecord(td, &random_systat.rsel);
}
return revents;
}
/* ARGSUSED */
static int
random_modevent(module_t mod __unused, int type, void *data __unused)
{
int error;
switch(type) {
case MOD_LOAD:
random_init();
/* This can be turned off by the very paranoid
* a reseed will turn it back on.
*/
random_systat.seeded = 1;
/* Number of envents to process off the harvest
* queue before giving it a break and sleeping
*/
random_systat.burst = 20;
/* Initialise the harvest ringbuffer */
harvestring.head = 0;
harvestring.tail = 0;
if (bootverbose)
printf("random: <entropy source>\n");
random_dev = make_dev(&random_cdevsw, RANDOM_MINOR, UID_ROOT,
GID_WHEEL, 0666, "random");
urandom_dev = make_dev_alias(random_dev, "urandom");
/* Start the hash/reseed thread */
error = kthread_create(random_kthread, NULL,
&random_kthread_proc, RFHIGHPID, "random");
if (error != 0)
return error;
/* Register the randomness harvesting routine */
random_init_harvester(random_harvest_internal,
read_random_real);
return 0;
case MOD_UNLOAD:
/* Deregister the randomness harvesting routine */
random_deinit_harvester();
/* Command the hash/reseed thread to end and
* wait for it to finish
*/
random_kthread_control = -1;
tsleep((void *)&random_kthread_control, PUSER, "term", 0);
random_deinit();
destroy_dev(random_dev);
destroy_dev(urandom_dev);
return 0;
case MOD_SHUTDOWN:
return 0;
default:
return EOPNOTSUPP;
}
}
DEV_MODULE(random, random_modevent, NULL);
/* ARGSUSED */
static void
random_kthread(void *arg __unused)
{
struct harvest *event;
u_int newtail, burst;
/* Drain the harvest queue (in 'burst' size chunks,
* if 'burst' > 0. If 'burst' == 0, then completely
* drain the queue.
*/
for (burst = 0; ; burst++) {
if ((harvestring.tail == harvestring.head) ||
(random_systat.burst && burst == random_systat.burst)) {
tsleep(&harvestring, PUSER, "sleep", hz/10);
burst = 0;
}
else {
/* Suck a harvested entropy event out of the queue and
* hand it to the event processor
*/
newtail = (harvestring.tail + 1) & HARVEST_RING_MASK;
event = &harvestring.data[harvestring.tail];
/* Bump the ring counter. This action is assumed
* to be atomic.
*/
harvestring.tail = newtail;
random_process_event(event);
}
/* Is the thread scheduled for a shutdown? */
if (random_kthread_control != 0) {
#ifdef DEBUG
mtx_lock(&Giant);
printf("Random kthread setting terminate\n");
mtx_unlock(&Giant);
#endif
random_set_wakeup_exit(&random_kthread_control);
/* NOTREACHED */
break;
}
}
}
/* Entropy harvesting routine. This is supposed to be fast; do
* not do anything slow in here!
*/
static void
random_harvest_internal(u_int64_t somecounter, void *entropy, u_int count,
u_int bits, u_int frac, enum esource origin)
{
struct harvest *pharvest;
u_int newhead;
newhead = (harvestring.head + 1) & HARVEST_RING_MASK;
if (newhead != harvestring.tail) {
/* Add the harvested data to the ring buffer */
pharvest = &harvestring.data[harvestring.head];
/* Stuff the harvested data into the ring */
pharvest->somecounter = somecounter;
count = count > HARVESTSIZE ? HARVESTSIZE : count;
memcpy(pharvest->entropy, entropy, count);
pharvest->size = count;
pharvest->bits = bits;
pharvest->frac = frac;
pharvest->source =
origin < ENTROPYSOURCE ? origin : RANDOM_START;
/* Bump the ring counter. This action is assumed
* to be atomic.
*/
harvestring.head = newhead;
}
}
static void
random_write_internal(void *buf, int count)
{
int i;
/* Break the input up into HARVESTSIZE chunks.
* The writer has too much control here, so "estimate" the
* the entropy as zero.
*/
for (i = 0; i < count; i += HARVESTSIZE) {
random_harvest_internal(get_cyclecount(), (char *)buf + i,
HARVESTSIZE, 0, 0, RANDOM_WRITE);
}
/* Maybe the loop iterated at least once */
if (i > count)
i -= HARVESTSIZE;
/* Get the last bytes even if the input length is not
* a multiple of HARVESTSIZE.
*/
count %= HARVESTSIZE;
if (count) {
random_harvest_internal(get_cyclecount(), (char *)buf + i,
(u_int)count, 0, 0, RANDOM_WRITE);
}
}
void
random_unblock(void)
{
if (!random_systat.seeded) {
random_systat.seeded = 1;
selwakeup(&random_systat.rsel);
wakeup(&random_systat);
}
}