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NetBSD/sys/dev/rnd.c

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/* $NetBSD: rnd.c,v 1.10 1997/10/20 18:43:48 explorer Exp $ */
/*-
* Copyright (c) 1997 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Michael Graff <explorer@flame.org>. This code uses ideas and
* algorithms from the Linux driver written by Ted Ts'o.
*
* 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.
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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/param.h>
#include <sys/ioctl.h>
#include <sys/fcntl.h>
#include <sys/select.h>
#include <sys/poll.h>
#include <sys/malloc.h>
#include <sys/md5.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/systm.h>
#include <sys/rnd.h>
#include <sys/vnode.h>
#ifdef RND_DEBUG
#define DPRINTF(l,x) if (rnd_debug & (l)) printf x
int rnd_debug = 0;
#else
#define DPRINTF(l,x)
#endif
#define RND_DEBUG_WRITE 0x0001
#define RND_DEBUG_READ 0x0002
#define RND_DEBUG_IOCTL 0x0004
#define RND_DEBUG_SNOOZE 0x0008
/*
* list devices attached
*/
/* #define RND_VERBOSE */
/*
* Use the extraction time as a somewhat-random source
*/
#ifndef RND_USE_EXTRACT_TIME
#define RND_USE_EXTRACT_TIME 1
#endif
/*
* The size of a temporary buffer, malloc()ed when needed, and used for
* reading and writing data.
*/
#define RND_TEMP_BUFFER_SIZE 128
/*
* This is the minimum amount of random data we can have and be
* considered "readable"
*/
#define RND_ENTROPY_THRESHOLD 64
typedef struct _rnd_event_t {
rndsource_t *source;
u_int32_t val;
u_int32_t timestamp;
} rnd_event_t;
/*
* the event queue. Fields are altered at an interrupt level.
*/
volatile int rnd_head;
volatile int rnd_tail;
volatile int rnd_timeout_pending;
volatile rnd_event_t rnd_events[RND_EVENTQSIZE];
/*
* our select/poll queue
*/
struct selinfo rnd_selq;
/*
* Set when there are readers blocking on data from us
*/
#define RND_READWAITING 0x00000001
volatile u_int32_t rnd_status;
/*
* our random pool. This is defined here rather than using the general
* purpose one defined in rndpool.c
*/
rndpool_t rnd_pool;
/*
* This is used for devices that pass a NULL source pointer into the
* rnd_add_*() functions. The user never sees this source, and cannot
* modify it.
*/
static rndsource_t rnd_source_no_estimate = {
{ 'U', 'n', 'k', 'n', 'o', 'w', 'n', 0, 0, 0, 0, 0, 0, 0, 0, 0 },
0, 0, 0, 0,
(RND_FLAG_NO_ESTIMATE | RND_TYPE_UNKNOWN)
};
/*
* This source is used to easily "remove" queue entries when the source
* which actually generated the events is going away.
*/
static rndsource_t rnd_source_no_collect = {
{ 'U', 'n', 'k', 'n', 'o', 'w', 'n', 0, 0, 0, 0, 0, 0, 0, 0, 0 },
0, 0, 0, 0,
(RND_FLAG_NO_COLLECT | RND_FLAG_NO_ESTIMATE | RND_TYPE_UNKNOWN)
};
void rndattach __P((int));
int rndopen __P((dev_t, int, int, struct proc *));
int rndclose __P((dev_t, int, int, struct proc *));
int rndread __P((dev_t, struct uio *, int));
int rndwrite __P((dev_t, struct uio *, int));
int rndioctl __P((dev_t, u_long, caddr_t, int, struct proc *));
int rndpoll __P((dev_t, int, struct proc *));
static inline void rnd_wakeup_readers(void);
static inline u_int32_t rnd_estimate_entropy(rndsource_t *, u_int32_t);
static inline u_int32_t rnd_timestamp(void);
static void rnd_timeout(void *);
/*
* Generate a 32-bit timestamp. This should be more machine dependant,
* using cycle counters and the like when possible.
*/
static inline u_int32_t
rnd_timestamp()
{
struct timeval tv;
u_int32_t t;
microtime(&tv);
t = tv.tv_sec * 1000000 + tv.tv_usec;
return t;
}
/*
* Check to see if there are readers waiting on us. If so, kick them.
*/
static inline void
rnd_wakeup_readers()
{
/*
* If we have added new bits, and now have enough to do something,
* wake up sleeping readers.
*/
if (rndpool_get_entropy_count(&rnd_pool) > RND_ENTROPY_THRESHOLD) {
if (rnd_status & RND_READWAITING) {
DPRINTF(RND_DEBUG_SNOOZE,
("waking up pending readers.\n"));
rnd_status &= ~RND_READWAITING;
wakeup(&rnd_selq);
}
selwakeup(&rnd_selq);
}
}
/*
* Use the timing of the event to estimate the entropy gathered.
* Note that right now we will return either one or two, depending on
* if all the differentials (first, second, and third) are non-zero.
*/
static inline u_int32_t
rnd_estimate_entropy(rs, t)
rndsource_t *rs;
u_int32_t t;
{
int32_t delta;
int32_t delta2;
int32_t delta3;
/*
* If the time counter has overflowed, calculate the real difference.
* If it has not, it is simplier.
*/
if (t < rs->last_time)
delta = UINT_MAX - rs->last_time + t;
else
delta = rs->last_time - t;
if (delta < 0)
delta = -delta;
/*
* Calculate the second and third order differentials
*/
delta2 = rs->last_delta - delta;
if (delta2 < 0)
delta2 = -delta2;
delta3 = rs->last_delta2 - delta2;
if (delta3 < 0)
delta3 = -delta3;
rs->last_time = t;
rs->last_delta = delta;
rs->last_delta2 = delta2;
/*
* If any delta is 0, we got no entropy. If all are non-zero, we
* got one bit.
*
* XXX This is probably too conservative, but better than that than
* too liberal.
*/
if (delta == 0 || delta2 == 0 || delta3 == 0)
return 0;
return 1;
}
static int rnd_ready;
LIST_HEAD(, __rndsource_element) rnd_sources;
/*
* attach the random device, and initialize the global random pool
* for our use.
*/
void
rndattach(num)
int num;
{
rnd_init();
}
int
rndopen(dev, flags, ifmt, p)
dev_t dev;
int flags, ifmt;
struct proc *p;
{
if (rnd_ready == 0)
return (ENXIO);
if (minor(dev) == RND_DEV_RANDOM || minor(dev) == RND_DEV_URANDOM)
return 0;
return (ENXIO);
}
int
rndclose(dev, flags, ifmt, p)
dev_t dev;
int flags, ifmt;
struct proc *p;
{
return (0);
}
int
rndread(dev, uio, ioflag)
dev_t dev;
struct uio *uio;
int ioflag;
{
int ret;
u_int32_t nread;
int n;
int s;
u_int8_t *buf;
u_int32_t mode;
u_int32_t entcnt;
DPRINTF(RND_DEBUG_READ,
("Random: Read of %d requested, flags 0x%08x\n",
uio->uio_resid, ioflag));
if (uio->uio_resid == 0)
return (0);
switch (minor(dev)) {
case RND_DEV_RANDOM:
mode = RND_EXTRACT_GOOD;
break;
case RND_DEV_URANDOM:
mode = RND_EXTRACT_ANY;
break;
default:
/* Can't happen, but this is cheap */
return (ENXIO);
}
ret = 0;
buf = malloc(RND_TEMP_BUFFER_SIZE, M_TEMP, M_WAITOK);
while (uio->uio_resid > 0) {
n = min(RND_TEMP_BUFFER_SIZE, uio->uio_resid);
/*
* Make certain there is data available. If there
* is, do the I/O even if it is partial. If not,
* sleep unless the user has requested non-blocking
* I/O.
*/
for (;;) {
/*
* If not requesting strong randomness, we
* can always read.
*/
if (mode == RND_EXTRACT_ANY)
break;
/*
* How much entropy do we have? If it is enough for
* one hash, we can read.
*/
s = splsoftclock();
entcnt = rndpool_get_entropy_count(&rnd_pool);
splx(s);
if (entcnt >= RND_ENTROPY_THRESHOLD)
break;
/*
* Data is not available.
*/
if (ioflag & IO_NDELAY) {
ret = EWOULDBLOCK;
goto out;
}
rnd_status |= RND_READWAITING;
ret = tsleep(&rnd_selq, PRIBIO|PCATCH,
"rndread", 0);
if (ret)
goto out;
}
nread = rnd_extract_data(buf, n, mode);
/*
* copy (possibly partial) data to the user.
* If an error occurs, or this is a partial
* read, bail out.
*/
ret = uiomove((caddr_t)buf, nread, uio);
if (ret != 0 || nread != n)
goto out;
}
out:
free(buf, M_TEMP);
return (ret);
}
int
rndwrite(dev, uio, ioflag)
dev_t dev;
struct uio *uio;
int ioflag;
{
u_int8_t *buf;
int ret;
int n;
int s;
DPRINTF(RND_DEBUG_WRITE,
("Random: Write of %d requested\n", uio->uio_resid));
if (uio->uio_resid == 0)
return (0);
ret = 0;
buf = malloc(RND_TEMP_BUFFER_SIZE, M_TEMP, M_WAITOK);
while (uio->uio_resid > 0) {
n = min(RND_TEMP_BUFFER_SIZE, uio->uio_resid);
ret = uiomove((caddr_t)buf, n, uio);
if (ret != 0)
break;
/*
* Mix in the bytes.
*/
s = splsoftclock();
rndpool_add_data(&rnd_pool, buf, n, 0);
splx(s);
DPRINTF(RND_DEBUG_WRITE, ("Random: Copied in %d bytes\n", n));
}
free(buf, M_TEMP);
return (ret);
}
int
rndioctl(dev, cmd, addr, flag, p)
dev_t dev;
u_long cmd;
caddr_t addr;
int flag;
struct proc *p;
{
int ret;
rndsource_element_t *rse;
rndstat_t *rst;
rndstat_name_t *rstnm;
rndctl_t *rctl;
rnddata_t *rnddata;
u_int32_t count;
u_int32_t start;
int s;
ret = 0;
switch (cmd) {
/*
* Handled in upper layer really, but we have to return zero
* for it to be accepted by the upper layer.
*/
case FIONBIO:
case FIOASYNC:
break;
case RNDGETENTCNT:
s = splsoftclock();
*(u_int32_t *)addr = rndpool_get_entropy_count(&rnd_pool);
splx(s);
break;
case RNDGETPOOL:
if ((ret = suser(p->p_ucred, &p->p_acflag)) != 0)
return (ret);
s = splsoftclock();
ret = copyout(rndpool_get_pool(&rnd_pool),
addr, rndpool_get_poolsize());
splx(s);
break;
case RNDADDTOENTCNT:
if ((ret = suser(p->p_ucred, &p->p_acflag)) != 0)
return (ret);
s = splsoftclock();
rndpool_increment_entropy_count(&rnd_pool, *(u_int32_t *)addr);
rnd_wakeup_readers();
splx(s);
break;
case RNDSETENTCNT:
if ((ret = suser(p->p_ucred, &p->p_acflag)) != 0)
return (ret);
s = splsoftclock();
rndpool_set_entropy_count(&rnd_pool, *(u_int32_t *)addr);
rnd_wakeup_readers();
splx(s);
break;
case RNDGETSRCNUM:
if ((ret = suser(p->p_ucred, &p->p_acflag)) != 0)
return (ret);
rst = (rndstat_t *)addr;
if (rst->count == 0)
break;
if (rst->count > RND_MAXSTATCOUNT)
return (EINVAL);
/*
* find the starting source by running through the
* list of sources.
*/
rse = rnd_sources.lh_first;
start = rst->start;
while (rse != NULL && start >= 1) {
rse = rse->list.le_next;
start--;
}
/*
* Return up to as many structures as the user asked
* for. If we run out of sources, a count of zero
* will be returned, without an error.
*/
for (count = 0 ; count < rst->count && rse != NULL ; count++) {
bcopy(&rse->data, &rst->source[count],
sizeof(rndsource_t));
rse = rse->list.le_next;
}
rst->count = count;
break;
case RNDGETSRCNAME:
if ((ret = suser(p->p_ucred, &p->p_acflag)) != 0)
return (ret);
/*
* scan through the list, trying to find the name
*/
rstnm = (rndstat_name_t *)addr;
rse = rnd_sources.lh_first;
while (rse != NULL) {
if (strncmp(rse->data.name, rstnm->name, 16) == 0) {
bcopy(&rse->data, &rstnm->source,
sizeof(rndsource_t));
return 0;
}
rse = rse->list.le_next;
}
ret = ENOENT; /* name not found */
break;
case RNDCTL:
if ((ret = suser(p->p_ucred, &p->p_acflag)) != 0)
return (ret);
/*
* set flags to enable/disable entropy counting and/or
* collection
*/
rctl = (rndctl_t *)addr;
rse = rnd_sources.lh_first;
/*
* flags set apply to all sources of this type
*/
if (rctl->type != 0xff) {
while (rse != NULL) {
if ((rse->data.tyfl & 0xff) == rctl->type) {
rse->data.tyfl &= ~rctl->mask;
rse->data.tyfl |= (rctl->flags
& rctl->mask);
}
rse = rse->list.le_next;
}
return 0;
}
/*
* scan through the list, trying to find the name
*/
while (rse != NULL) {
if (strncmp(rse->data.name, rctl->name, 16) == 0) {
rse->data.tyfl &= ~rctl->mask;
rse->data.tyfl |= (rctl->flags & rctl->mask);
return 0;
}
rse = rse->list.le_next;
}
ret = ENOENT; /* name not found */
break;
case RNDADDDATA:
if ((ret = suser(p->p_ucred, &p->p_acflag)) != 0)
return (ret);
rnddata = (rnddata_t *)addr;
s = splsoftclock();
rndpool_add_data(&rnd_pool, rnddata->data, rnddata->len,
rnddata->entropy);
rnd_wakeup_readers();
splx(s);
break;
default:
return (EINVAL);
}
return (ret);
}
int
rndpoll(dev, events, p)
dev_t dev;
int events;
struct proc *p;
{
int revents;
int s;
u_int32_t entcnt;
/*
* we are always writable
*/
revents = events & (POLLOUT | POLLWRNORM);
/*
* Save some work if not checking for reads
*/
if ((events & (POLLIN | POLLRDNORM)) == 0)
return (revents);
/*
* If the minor device is not /dev/random, we are always readable.
*/
if (minor(dev) != RND_DEV_RANDOM) {
revents |= events & (POLLIN | POLLRDNORM);
return (revents);
}
/*
* make certain we have enough entropy to be readable
*/
s = splsoftclock();
entcnt = rndpool_get_entropy_count(&rnd_pool);
splx(s);
if (entcnt >= RND_ENTROPY_THRESHOLD)
revents |= events & (POLLIN | POLLRDNORM);
else
selrecord(p, &rnd_selq);
return (revents);
}
/*
* initialize the data for the random generator.
*/
void
rnd_init(void)
{
if (rnd_ready)
return;
LIST_INIT(&rnd_sources);
rnd_head = 0;
rnd_tail = 0;
rndpool_init(&rnd_pool);
rnd_ready = 1;
#ifdef RND_VERBOSE
printf("Random device ready\n");
#endif
}
/*
* add a source to our list of sources
*/
void
rnd_attach_source(rs, name, tyfl)
rndsource_element_t *rs;
char *name;
u_int32_t tyfl;
{
strcpy(rs->data.name, name);
/*
* force network devices to not collect any entropy by
* default
*/
if ((tyfl & 0x00ff) == RND_TYPE_NET)
tyfl |= RND_FLAG_NO_ESTIMATE;
rs->data.tyfl = tyfl;
LIST_INSERT_HEAD(&rnd_sources, rs, list);
#ifdef RND_VERBOSE
printf("%s: attached as an entropy source\n", rs->data.name);
#endif
}
/*
* remove a source from our list of sources
*/
void
rnd_detach_source(rs)
rndsource_element_t *rs;
{
int elem;
volatile rnd_event_t *ev;
int s;
s = splhigh();
LIST_REMOVE(rs, list);
/*
* If there are events queued up, "remove" them from the event queue
*/
elem = rnd_tail;
while (elem != rnd_head) {
ev = &rnd_events[elem];
if (ev->source == &rs->data)
ev->source = &rnd_source_no_collect;
elem = (elem + 1) & (RND_EVENTQSIZE - 1);
}
splx(s);
}
/*
* Add a value to the entropy pool. If rs is NULL no entropy estimation
* will be performed, otherwise it should point to the source-specific
* source structure.
*/
void
rnd_add_uint32(rs, val)
rndsource_element_t *rs;
u_int32_t val;
{
rndsource_t *rst;
volatile rnd_event_t *ev;
int s;
int nexthead;
s = splhigh();
/*
* check for full ring. If the queue is full and we have not
* already scheduled a timeout, do so here.
*/
nexthead = (rnd_head + 1) & (RND_EVENTQSIZE - 1);
if (nexthead == rnd_tail) {
if (rnd_timeout_pending == 0) {
rnd_timeout_pending = 1;
timeout(rnd_timeout, NULL, 1);
}
splx(s);
return;
}
/*
* If the source is null, we don't want to estimate, but we will
* collect. Point to our internal source definition for this.
*/
if (rs == NULL)
rst = &rnd_source_no_estimate;
else
rst = &rs->data;
/*
* If we are not collecting any data at all, just return.
*/
if (rst->tyfl & RND_FLAG_NO_COLLECT) {
splx(s);
return;
}
/*
* Otherwise, queue it up for later addition, and schedule a
* timeout to process it. Since we are at splhigh, this is
* an atomic operation...
*/
ev = &rnd_events[rnd_head];
ev->source = rst;
ev->val = val;
ev->timestamp = rnd_timestamp();
rnd_head = nexthead;
if (rnd_timeout_pending == 0) {
rnd_timeout_pending = 1;
timeout(rnd_timeout, NULL, 1);
}
splx(s);
}
/*
* timeout, run to process the events in the ring buffer. Only one of these
* can possibly be running at a time, and we are run at splsoftclock().
*/
static void
rnd_timeout(arg)
void *arg;
{
u_int32_t entropy;
volatile rnd_event_t *ev;
rnd_timeout_pending = 0;
/*
* check for empty queue
*/
if (rnd_head == rnd_tail)
return;
/*
* Run through the event queue, processing events.
*/
while (rnd_head != rnd_tail) {
ev = &rnd_events[rnd_tail];
/*
* We repeat this check here, since it is possible the source
* was disabled before we were called, but after the entry
* was queued.
*/
if ((ev->source->tyfl & RND_FLAG_NO_COLLECT) == 0) {
rndpool_add_uint32(&rnd_pool, ev->val, 0);
/*
* If we are not estimating entropy from this source,
* assume zero. We still add the timestamp, just
* don't bother calculating the estimation.
*/
if (ev->source->tyfl & RND_FLAG_NO_ESTIMATE)
entropy = 0;
else
entropy = rnd_estimate_entropy(ev->source,
ev->timestamp);
rndpool_add_uint32(&rnd_pool, ev->timestamp, entropy);
ev->source->total += entropy;
}
rnd_tail = (rnd_tail + 1) & (RND_EVENTQSIZE - 1);
}
/*
* wake up any potential readers waiting.
*/
rnd_wakeup_readers();
}
void
rnd_add_data(rs, p, len, entropy)
rndsource_element_t *rs;
void *p;
u_int32_t len;
u_int32_t entropy;
{
rndsource_t *rst;
int s;
u_int32_t t;
/*
* if the caller is trying to add more entropy than can possibly
* be in the buffer we are passed, ignore the whole thing.
*/
if (entropy > len * 8)
return;
s = splsoftclock();
/*
* If the source is null, we don't want to estimate, but we will
* collect.
*/
if (rs == NULL)
rst = &rnd_source_no_estimate;
else
rst = &rs->data;
/*
* If we are not collecting any data at all, just return.
*/
if (rst->tyfl & RND_FLAG_NO_COLLECT) {
splx(s);
return;
}
rndpool_add_data(&rnd_pool, p, len, entropy);
/*
* If we are not estimating timing entropy from this source, add
* the timestamp and assume zero entropy from timing info.
*/
t = rnd_timestamp();
if (rst->tyfl & RND_FLAG_NO_ESTIMATE)
entropy = 0;
else
entropy = rnd_estimate_entropy(rst, t);
rndpool_add_uint32(&rnd_pool, t, entropy);
rst->total += entropy;
rnd_wakeup_readers();
splx(s);
}
int
rnd_extract_data(p, len, flags)
void *p;
u_int32_t len;
u_int32_t flags;
{
int s;
int retval;
s = splsoftclock();
#if RND_USE_EXTRACT_TIME
rndpool_add_uint32(&rnd_pool, rnd_timestamp(), 0);
#endif
retval = rndpool_extract_data(&rnd_pool, p, len, flags);
splx(s);
return retval;
}
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