OpenSolaris_b135/uts/common/io/random.c
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*
* Copyright 2009 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/*
* Random number generator pseudo-driver
*
* This is a lightweight driver which calls in to the Kernel Cryptographic
* Framework to do the real work. Kernel modules should NOT depend on this
* driver for /dev/random kernel API.
*
* Applications may ask for 2 types of random bits:
* . High quality random by reading from /dev/random. The output is extracted
* only when a minimum amount of entropy is available.
* . Pseudo-random, by reading from /dev/urandom, that can be generated any
* time.
*/
#include <sys/types.h>
#include <sys/errno.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/open.h>
#include <sys/poll.h>
#include <sys/uio.h>
#include <sys/cred.h>
#include <sys/modctl.h>
#include <sys/conf.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#include <sys/random.h>
#include <sys/crypto/impl.h>
#define DEVRANDOM 0
#define DEVURANDOM 1
#define HASHSIZE 20 /* Assuming a SHA1 hash algorithm */
#define WRITEBUFSIZE 512 /* Size of buffer for write request */
#define MAXRETBYTES 1040 /* Max bytes returned per read. */
/* Must be a multiple of HASHSIZE */
static dev_info_t *rnd_dip;
static int rnd_open(dev_t *, int, int, cred_t *);
static int rnd_close(dev_t, int, int, cred_t *);
static int rnd_read(dev_t, struct uio *, cred_t *);
static int rnd_write(dev_t, struct uio *, cred_t *);
static int rnd_chpoll(dev_t, short, int, short *, struct pollhead **);
static int rnd_attach(dev_info_t *, ddi_attach_cmd_t);
static int rnd_detach(dev_info_t *, ddi_detach_cmd_t);
static int rnd_getinfo(dev_info_t *, ddi_info_cmd_t, void *, void **);
/* DDI declarations */
static struct cb_ops rnd_cb_ops = {
rnd_open, /* open */
rnd_close, /* close */
nodev, /* strategy */
nodev, /* print */
nodev, /* dump */
rnd_read, /* read */
rnd_write, /* write */
nodev, /* ioctl */
nodev, /* devmap */
nodev, /* mmap */
nodev, /* segmap */
rnd_chpoll, /* chpoll */
ddi_prop_op, /* prop_op */
NULL, /* streamtab */
(D_NEW | D_MP), /* cb_flag */
CB_REV, /* cb_rev */
nodev, /* aread */
nodev /* awrite */
};
static struct dev_ops rnd_ops = {
DEVO_REV, /* devo_rev, */
0, /* refcnt */
rnd_getinfo, /* get_dev_info */
nulldev, /* identify */
nulldev, /* probe */
rnd_attach, /* attach */
rnd_detach, /* detach */
nodev, /* reset */
&rnd_cb_ops, /* driver operations */
NULL, /* bus operations */
NULL, /* power */
ddi_quiesce_not_needed, /* quiesce */
};
/* Modlinkage */
static struct modldrv modldrv = {
&mod_driverops,
"random number device",
&rnd_ops
};
static struct modlinkage modlinkage = { MODREV_1, { &modldrv, NULL } };
/* DDI glue */
int
_init(void)
{
return (mod_install(&modlinkage));
}
int
_fini(void)
{
return (mod_remove(&modlinkage));
}
int
_info(struct modinfo *modinfop)
{
return (mod_info(&modlinkage, modinfop));
}
static int
rnd_attach(dev_info_t *dip, ddi_attach_cmd_t cmd)
{
if (cmd != DDI_ATTACH)
return (DDI_FAILURE);
if (ddi_create_minor_node(dip, "random", S_IFCHR, DEVRANDOM,
DDI_PSEUDO, 0) == DDI_FAILURE) {
ddi_remove_minor_node(dip, NULL);
return (DDI_FAILURE);
}
if (ddi_create_minor_node(dip, "urandom", S_IFCHR, DEVURANDOM,
DDI_PSEUDO, 0) == DDI_FAILURE) {
ddi_remove_minor_node(dip, NULL);
return (DDI_FAILURE);
}
rnd_dip = dip;
return (DDI_SUCCESS);
}
static int
rnd_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
{
if (cmd != DDI_DETACH)
return (DDI_FAILURE);
rnd_dip = NULL;
ddi_remove_minor_node(dip, NULL);
return (DDI_SUCCESS);
}
/*ARGSUSED*/
static int
rnd_getinfo(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
{
int error;
switch (infocmd) {
case DDI_INFO_DEVT2DEVINFO:
*result = rnd_dip;
error = DDI_SUCCESS;
break;
case DDI_INFO_DEVT2INSTANCE:
*result = (void *)0;
error = DDI_SUCCESS;
break;
default:
error = DDI_FAILURE;
}
return (error);
}
/*ARGSUSED3*/
static int
rnd_open(dev_t *devp, int flag, int otyp, cred_t *credp)
{
switch (getminor(*devp)) {
case DEVRANDOM:
if (!kcf_rngprov_check())
return (ENXIO);
break;
case DEVURANDOM:
break;
default:
return (ENXIO);
}
if (otyp != OTYP_CHR)
return (EINVAL);
if (flag & FEXCL)
return (EINVAL);
return (0);
}
/*ARGSUSED*/
static int
rnd_close(dev_t dev, int flag, int otyp, cred_t *credp)
{
return (0);
}
/*ARGSUSED2*/
static int
rnd_read(dev_t dev, struct uio *uiop, cred_t *credp)
{
size_t len;
minor_t devno;
int error = 0;
int nbytes = 0;
uint8_t random_bytes[2 * HASHSIZE];
devno = getminor(dev);
while (error == 0 && uiop->uio_resid > 0) {
len = min(sizeof (random_bytes), uiop->uio_resid);
switch (devno) {
case DEVRANDOM:
error = kcf_rnd_get_bytes(random_bytes, len,
uiop->uio_fmode & (FNDELAY|FNONBLOCK));
break;
case DEVURANDOM:
error = kcf_rnd_get_pseudo_bytes(random_bytes, len);
break;
default:
return (ENXIO);
}
if (error == 0) {
/*
* /dev/[u]random is not a seekable device. To prevent
* uio offset from growing and eventually exceeding
* the maximum, reset the offset here for every call.
*/
uiop->uio_loffset = 0;
error = uiomove(random_bytes, len, UIO_READ, uiop);
nbytes += len;
if (devno == DEVRANDOM && nbytes >= MAXRETBYTES)
break;
} else if ((error == EAGAIN) && (nbytes > 0)) {
error = 0;
break;
}
}
return (error);
}
/*ARGSUSED*/
static int
rnd_write(dev_t dev, struct uio *uiop, cred_t *credp)
{
int error;
uint8_t buf[WRITEBUFSIZE];
size_t bytes;
minor_t devno;
devno = getminor(dev);
while (uiop->uio_resid > 0) {
bytes = min(sizeof (buf), uiop->uio_resid);
/* See comments in rnd_read() */
uiop->uio_loffset = 0;
if ((error = uiomove(buf, bytes, UIO_WRITE, uiop)) != 0)
return (error);
switch (devno) {
case DEVRANDOM:
if ((error = random_add_entropy(buf, bytes, 0)) != 0)
return (error);
break;
case DEVURANDOM:
if ((error = random_add_pseudo_entropy(buf, bytes,
0)) != 0)
return (error);
break;
default:
return (ENXIO);
}
}
return (0);
}
static struct pollhead urnd_pollhd;
/*
* poll(2) is supported as follows:
* . Only POLLIN, POLLOUT, and POLLRDNORM events are supported.
* . POLLOUT always succeeds.
* . POLLIN and POLLRDNORM from /dev/urandom always succeeds.
* . POLLIN and POLLRDNORM from /dev/random will block until a
* minimum amount of entropy is available.
*/
static int
rnd_chpoll(dev_t dev, short events, int anyyet, short *reventsp,
struct pollhead **phpp)
{
switch (getminor(dev)) {
case DEVURANDOM:
*reventsp = events & (POLLOUT | POLLIN | POLLRDNORM);
/*
* A non NULL pollhead pointer should be returned in case
* user polls for 0 events.
*/
if (*reventsp == 0 && !anyyet)
*phpp = &urnd_pollhd;
break;
case DEVRANDOM:
kcf_rnd_chpoll(events, anyyet, reventsp, phpp);
break;
default:
return (ENXIO);
}
return (0);
}