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NetBSD/sys/dev/rndpseudo.c

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/* $NetBSD: rndpseudo.c,v 1.6 2011/12/20 13:42:19 apb Exp $ */
/*-
* Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Michael Graff <explorer@flame.org> and Thor Lancelot Simon.
*
* 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.
*
* 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: rndpseudo.c,v 1.6 2011/12/20 13:42:19 apb Exp $");
#if defined(_KERNEL_OPT)
#include "opt_compat_netbsd.h"
#endif
#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/select.h>
#include <sys/poll.h>
#include <sys/kmem.h>
#include <sys/atomic.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/systm.h>
#include <sys/vnode.h>
#include <sys/pool.h>
#include <sys/kauth.h>
#include <sys/cprng.h>
#include <sys/stat.h>
#include <sys/rnd.h>
#ifdef COMPAT_50
#include <compat/sys/rnd.h>
#endif
#include <dev/rnd_private.h>
#if defined(__HAVE_CPU_COUNTER) && !defined(_RUMPKERNEL) /* XXX: bad pooka */
#include <machine/cpu_counter.h>
#endif
#ifdef RND_DEBUG
#define DPRINTF(l,x) if (rnd_debug & (l)) printf x
extern int rnd_debug;
#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
*/
#if 0
#define RND_VERBOSE
#endif
/*
* The size of a temporary buffer, kmem_alloc()ed when needed, and used for
* reading and writing data.
*/
#define RND_TEMP_BUFFER_SIZE 512
static pool_cache_t rp_pc;
static pool_cache_t rp_cpc;
/*
* A context. cprng plus a smidge.
*/
typedef struct {
cprng_strong_t *cprng;
int hard;
int bytesonkey;
kmutex_t interlock;
} rp_ctx_t;
/*
* Our random pool. This is defined here rather than using the general
* purpose one defined in rndpool.c.
*
* Samples are collected and queued into a separate mutex-protected queue
* (rnd_samples, see above), and processed in a timeout routine; therefore,
* the mutex protecting the random pool is at IPL_SOFTCLOCK() as well.
*/
extern rndpool_t rnd_pool;
extern kmutex_t rndpool_mtx;
void rndattach(int);
dev_type_open(rndopen);
const struct cdevsw rnd_cdevsw = {
rndopen, noclose, noread, nowrite, noioctl, nostop,
notty, nopoll, nommap, nokqfilter, D_OTHER|D_MPSAFE
};
static int rnd_read(struct file *, off_t *, struct uio *, kauth_cred_t, int);
static int rnd_write(struct file *, off_t *, struct uio *, kauth_cred_t, int);
static int rnd_ioctl(struct file *, u_long, void *);
static int rnd_poll(struct file *, int);
static int rnd_stat(struct file *, struct stat *);
static int rnd_close(struct file *);
static int rnd_kqfilter(struct file *, struct knote *);
const struct fileops rnd_fileops = {
.fo_read = rnd_read,
.fo_write = rnd_write,
.fo_ioctl = rnd_ioctl,
.fo_fcntl = fnullop_fcntl,
.fo_poll = rnd_poll,
.fo_stat = rnd_stat,
.fo_close = rnd_close,
.fo_kqfilter = rnd_kqfilter,
.fo_restart = fnullop_restart
};
void rnd_wakeup_readers(void); /* XXX */
extern int rnd_ready; /* XXX */
extern rndsave_t *boot_rsp; /* XXX */
extern LIST_HEAD(, krndsource) rnd_sources; /* XXX */
/*
* Generate a 32-bit counter. This should be more machine dependent,
* using cycle counters and the like when possible.
*/
static inline u_int32_t
rndpseudo_counter(void)
{
struct timeval tv;
#if defined(__HAVE_CPU_COUNTER) && !defined(_RUMPKERNEL) /* XXX: bad pooka */
if (cpu_hascounter())
return (cpu_counter32());
#endif
microtime(&tv);
return (tv.tv_sec * 1000000 + tv.tv_usec);
}
/*
* "Attach" the random device. This is an (almost) empty stub, since
* pseudo-devices don't get attached until after config, after the
* entropy sources will attach. We just use the timing of this event
* as another potential source of initial entropy.
*/
void
rndattach(int num)
{
u_int32_t c;
/* Trap unwary players who don't call rnd_init() early */
KASSERT(rnd_ready);
rp_pc = pool_cache_init(RND_TEMP_BUFFER_SIZE, 0, 0, 0,
"rndtemp", NULL, IPL_NONE,
NULL, NULL, NULL);
rp_cpc = pool_cache_init(sizeof(rp_ctx_t), 0, 0, 0,
"rndctx", NULL, IPL_NONE,
NULL, NULL, NULL);
/* mix in another counter */
c = rndpseudo_counter();
mutex_spin_enter(&rndpool_mtx);
rndpool_add_data(&rnd_pool, &c, sizeof(u_int32_t), 1);
mutex_spin_exit(&rndpool_mtx);
}
int
rndopen(dev_t dev, int flag, int ifmt,
struct lwp *l)
{
rp_ctx_t *ctx;
file_t *fp;
int fd, hard, error = 0;
switch (minor(dev)) {
case RND_DEV_URANDOM:
hard = 0;
break;
case RND_DEV_RANDOM:
hard = 1;
break;
default:
return ENXIO;
}
ctx = pool_cache_get(rp_cpc, PR_WAITOK);
ctx->cprng = NULL;
ctx->hard = hard;
mutex_init(&ctx->interlock, MUTEX_DEFAULT, IPL_NONE);
if ((error = fd_allocfile(&fp, &fd)) != 0) {
pool_cache_put(rp_cpc, ctx);
return error;
}
return fd_clone(fp, fd, flag, &rnd_fileops, ctx);
}
static void
rnd_alloc_cprng(rp_ctx_t *ctx)
{
char personalization_buf[64];
struct lwp *l = curlwp;
int cflags = ctx->hard ? CPRNG_USE_CV :
CPRNG_INIT_ANY|CPRNG_REKEY_ANY;
mutex_enter(&ctx->interlock);
if (__predict_true(ctx->cprng == NULL)) {
snprintf(personalization_buf,
sizeof(personalization_buf),
"%d%llud%d", l->l_proc->p_pid,
(unsigned long long int)l->l_ncsw, l->l_cpticks);
ctx->cprng = cprng_strong_create(personalization_buf,
IPL_NONE, cflags);
}
membar_sync();
mutex_exit(&ctx->interlock);
}
static int
rnd_read(struct file * fp, off_t *offp, struct uio *uio,
kauth_cred_t cred, int flags)
{
rp_ctx_t *ctx = fp->f_data;
u_int8_t *bf;
int strength, ret;
DPRINTF(RND_DEBUG_READ,
("Random: Read of %zu requested, flags 0x%08x\n",
uio->uio_resid, flags));
if (uio->uio_resid == 0)
return (0);
if (ctx->cprng == NULL) {
rnd_alloc_cprng(ctx);
if (__predict_false(ctx->cprng == NULL)) {
return EIO;
}
}
strength = cprng_strong_strength(ctx->cprng);
ret = 0;
bf = pool_cache_get(rp_pc, PR_WAITOK);
while (uio->uio_resid > 0) {
int n, nread, want;
want = MIN(RND_TEMP_BUFFER_SIZE, uio->uio_resid);
/* XXX is this _really_ what's wanted? */
if (ctx->hard) {
n = MIN(want, strength - ctx->bytesonkey);
ctx->bytesonkey += n;
} else {
n = want;
}
nread = cprng_strong(ctx->cprng, bf, n,
(fp->f_flag & FNONBLOCK) ? FNONBLOCK : 0);
if (nread != n) {
if (fp->f_flag & FNONBLOCK) {
ret = EWOULDBLOCK;
} else {
ret = EINTR;
}
goto out;
}
ret = uiomove((void *)bf, nread, uio);
if (ret != 0 || n < want) {
goto out;
}
}
out:
if (ctx->bytesonkey >= strength) {
/* Force reseed of underlying DRBG (prediction resistance) */
cprng_strong_deplete(ctx->cprng);
ctx->bytesonkey = 0;
}
pool_cache_put(rp_pc, bf);
return (ret);
}
static int
rnd_write(struct file *fp, off_t *offp, struct uio *uio,
kauth_cred_t cred, int flags)
{
u_int8_t *bf;
int n, ret = 0, estimate_ok = 0, estimate = 0, added = 0;
ret = kauth_authorize_device(cred,
KAUTH_DEVICE_RND_ADDDATA, NULL, NULL, NULL, NULL);
if (ret) {
return (ret);
}
estimate_ok = !kauth_authorize_device(cred,
KAUTH_DEVICE_RND_ADDDATA_ESTIMATE, NULL, NULL, NULL, NULL);
DPRINTF(RND_DEBUG_WRITE,
("Random: Write of %zu requested\n", uio->uio_resid));
if (uio->uio_resid == 0)
return (0);
ret = 0;
bf = pool_cache_get(rp_pc, PR_WAITOK);
while (uio->uio_resid > 0) {
/*
* Don't flood the pool.
*/
if (added > RND_POOLWORDS * sizeof(int)) {
#ifdef RND_VERBOSE
printf("rnd: added %d already, adding no more.\n",
added);
#endif
break;
}
n = min(RND_TEMP_BUFFER_SIZE, uio->uio_resid);
ret = uiomove((void *)bf, n, uio);
if (ret != 0)
break;
if (estimate_ok) {
/*
* Don't cause samples to be discarded by taking
* the pool's entropy estimate to the max.
*/
if (added > RND_POOLWORDS / 2)
estimate = 0;
else
estimate = n * NBBY / 2;
#ifdef RND_VERBOSE
printf("rnd: adding on write, %d bytes, estimate %d\n",
n, estimate);
#endif
} else {
#ifdef RND_VERBOSE
printf("rnd: kauth says no entropy.\n");
#endif
}
/*
* Mix in the bytes.
*/
mutex_spin_enter(&rndpool_mtx);
rndpool_add_data(&rnd_pool, bf, n, estimate);
mutex_spin_exit(&rndpool_mtx);
added += n;
DPRINTF(RND_DEBUG_WRITE, ("Random: Copied in %d bytes\n", n));
}
pool_cache_put(rp_pc, bf);
return (ret);
}
static void
krndsource_to_rndsource(krndsource_t *kr, rndsource_t *r)
{
memset(r, 0, sizeof(*r));
strlcpy(r->name, kr->name, sizeof(r->name));
r->total = kr->total;
r->type = kr->type;
r->flags = kr->flags;
}
int
rnd_ioctl(struct file *fp, u_long cmd, void *addr)
{
krndsource_t *kr;
rndstat_t *rst;
rndstat_name_t *rstnm;
rndctl_t *rctl;
rnddata_t *rnddata;
u_int32_t count, start;
int ret = 0;
int estimate_ok = 0, estimate = 0;
switch (cmd) {
case FIONBIO:
case FIOASYNC:
case RNDGETENTCNT:
break;
case RNDGETPOOLSTAT:
case RNDGETSRCNUM:
case RNDGETSRCNAME:
ret = kauth_authorize_device(curlwp->l_cred,
KAUTH_DEVICE_RND_GETPRIV, NULL, NULL, NULL, NULL);
if (ret)
return (ret);
break;
case RNDCTL:
ret = kauth_authorize_device(curlwp->l_cred,
KAUTH_DEVICE_RND_SETPRIV, NULL, NULL, NULL, NULL);
if (ret)
return (ret);
break;
case RNDADDDATA:
ret = kauth_authorize_device(curlwp->l_cred,
KAUTH_DEVICE_RND_ADDDATA, NULL, NULL, NULL, NULL);
if (ret)
return (ret);
estimate_ok = !kauth_authorize_device(curlwp->l_cred,
KAUTH_DEVICE_RND_ADDDATA_ESTIMATE, NULL, NULL, NULL, NULL);
break;
default:
#ifdef COMPAT_50
return compat_50_rnd_ioctl(fp, cmd, addr);
#else
return ENOTTY;
#endif
}
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:
mutex_spin_enter(&rndpool_mtx);
*(u_int32_t *)addr = rndpool_get_entropy_count(&rnd_pool);
mutex_spin_exit(&rndpool_mtx);
break;
case RNDGETPOOLSTAT:
mutex_spin_enter(&rndpool_mtx);
rndpool_get_stats(&rnd_pool, addr, sizeof(rndpoolstat_t));
mutex_spin_exit(&rndpool_mtx);
break;
case RNDGETSRCNUM:
rst = (rndstat_t *)addr;
if (rst->count == 0)
break;
if (rst->count > RND_MAXSTATCOUNT)
return (EINVAL);
mutex_spin_enter(&rndpool_mtx);
/*
* Find the starting source by running through the
* list of sources.
*/
kr = rnd_sources.lh_first;
start = rst->start;
while (kr != NULL && start >= 1) {
kr = kr->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 && kr != NULL; count++) {
krndsource_to_rndsource(kr, &rst->source[count]);
kr = kr->list.le_next;
}
rst->count = count;
mutex_spin_exit(&rndpool_mtx);
break;
case RNDGETSRCNAME:
/*
* Scan through the list, trying to find the name.
*/
mutex_spin_enter(&rndpool_mtx);
rstnm = (rndstat_name_t *)addr;
kr = rnd_sources.lh_first;
while (kr != NULL) {
if (strncmp(kr->name, rstnm->name,
MIN(sizeof(kr->name),
sizeof(*rstnm))) == 0) {
krndsource_to_rndsource(kr, &rstnm->source);
mutex_spin_exit(&rndpool_mtx);
return (0);
}
kr = kr->list.le_next;
}
mutex_spin_exit(&rndpool_mtx);
ret = ENOENT; /* name not found */
break;
case RNDCTL:
/*
* Set flags to enable/disable entropy counting and/or
* collection.
*/
mutex_spin_enter(&rndpool_mtx);
rctl = (rndctl_t *)addr;
kr = rnd_sources.lh_first;
/*
* Flags set apply to all sources of this type.
*/
if (rctl->type != 0xff) {
while (kr != NULL) {
if (kr->type == rctl->type) {
kr->flags &= ~rctl->mask;
kr->flags |=
(rctl->flags & rctl->mask);
}
kr = kr->list.le_next;
}
mutex_spin_exit(&rndpool_mtx);
return (0);
}
/*
* scan through the list, trying to find the name
*/
while (kr != NULL) {
if (strncmp(kr->name, rctl->name,
MIN(sizeof(kr->name),
sizeof(rctl->name))) == 0) {
kr->flags &= ~rctl->mask;
kr->flags |= (rctl->flags & rctl->mask);
mutex_spin_exit(&rndpool_mtx);
return (0);
}
kr = kr->list.le_next;
}
mutex_spin_exit(&rndpool_mtx);
ret = ENOENT; /* name not found */
break;
case RNDADDDATA:
/*
* Don't seed twice if our bootloader has
* seed loading support.
*/
if (!boot_rsp) {
rnddata = (rnddata_t *)addr;
if (rnddata->len > sizeof(rnddata->data))
return EINVAL;
if (estimate_ok) {
/*
* Do not accept absurd entropy estimates, and
* do not flood the pool with entropy such that
* new samples are discarded henceforth.
*/
estimate = MIN((rnddata->len * NBBY) / 2,
MIN(rnddata->entropy,
RND_POOLBITS / 2));
} else {
estimate = 0;
}
mutex_spin_enter(&rndpool_mtx);
rndpool_add_data(&rnd_pool, rnddata->data,
rnddata->len, estimate);
mutex_spin_exit(&rndpool_mtx);
rnd_wakeup_readers();
}
#ifdef RND_VERBOSE
else {
printf("rnd: already seeded by boot loader\n");
}
#endif
break;
default:
return ENOTTY;
}
return (ret);
}
static int
rnd_poll(struct file *fp, int events)
{
int revents;
rp_ctx_t *ctx = fp->f_data;
/*
* We are always writable.
*/
revents = events & (POLLOUT | POLLWRNORM);
/*
* Save some work if not checking for reads.
*/
if ((events & (POLLIN | POLLRDNORM)) == 0)
return (revents);
if (ctx->cprng == NULL) {
rnd_alloc_cprng(ctx);
if (__predict_false(ctx->cprng == NULL)) {
return EIO;
}
}
if (cprng_strong_ready(ctx->cprng)) {
revents |= events & (POLLIN | POLLRDNORM);
} else {
mutex_enter(&ctx->cprng->mtx);
selrecord(curlwp, &ctx->cprng->selq);
mutex_exit(&ctx->cprng->mtx);
}
return (revents);
}
static int
rnd_stat(struct file *fp, struct stat *st)
{
rp_ctx_t *ctx = fp->f_data;
/* XXX lock, if cprng allocated? why? */
memset(st, 0, sizeof(*st));
st->st_dev = makedev(cdevsw_lookup_major(&rnd_cdevsw),
ctx->hard ? RND_DEV_RANDOM :
RND_DEV_URANDOM);
/* XXX leave atimespect, mtimespec, ctimespec = 0? */
st->st_uid = kauth_cred_geteuid(fp->f_cred);
st->st_gid = kauth_cred_getegid(fp->f_cred);
st->st_mode = S_IFCHR;
return 0;
}
static int
rnd_close(struct file *fp)
{
rp_ctx_t *ctx = fp->f_data;
if (ctx->cprng) {
cprng_strong_destroy(ctx->cprng);
}
fp->f_data = NULL;
mutex_destroy(&ctx->interlock);
pool_cache_put(rp_cpc, ctx);
return 0;
}
static void
filt_rnddetach(struct knote *kn)
{
cprng_strong_t *c = kn->kn_hook;
mutex_enter(&c->mtx);
SLIST_REMOVE(&c->selq.sel_klist, kn, knote, kn_selnext);
mutex_exit(&c->mtx);
}
static int
filt_rndread(struct knote *kn, long hint)
{
cprng_strong_t *c = kn->kn_hook;
if (cprng_strong_ready(c)) {
kn->kn_data = RND_TEMP_BUFFER_SIZE;
return 1;
}
return 0;
}
static const struct filterops rnd_seltrue_filtops =
{ 1, NULL, filt_rnddetach, filt_seltrue };
static const struct filterops rndread_filtops =
{ 1, NULL, filt_rnddetach, filt_rndread };
static int
rnd_kqfilter(struct file *fp, struct knote *kn)
{
rp_ctx_t *ctx = fp->f_data;
struct klist *klist;
if (ctx->cprng == NULL) {
rnd_alloc_cprng(ctx);
if (__predict_false(ctx->cprng == NULL)) {
return EIO;
}
}
mutex_enter(&ctx->cprng->mtx);
switch (kn->kn_filter) {
case EVFILT_READ:
klist = &ctx->cprng->selq.sel_klist;
kn->kn_fop = &rndread_filtops;
break;
case EVFILT_WRITE:
klist = &ctx->cprng->selq.sel_klist;
kn->kn_fop = &rnd_seltrue_filtops;
break;
default:
mutex_exit(&ctx->cprng->mtx);
return EINVAL;
}
kn->kn_hook = ctx->cprng;
SLIST_INSERT_HEAD(klist, kn, kn_selnext);
mutex_exit(&ctx->cprng->mtx);
return (0);
}
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