xref: /dflybsd-src/sys/dev/crypto/rdrand/rdrand.c (revision 83c3760782ba564d010efd016db0045fd25a1aa4)

/*
 * Copyright (c) 2012 Alex Hornung <alex@alexhornung.com>.
 * 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.
 * 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 COPYRIGHT HOLDERS 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
 * COPYRIGHT HOLDERS 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/systm.h>
#include <sys/kernel.h>
#include <sys/kobj.h>
#include <sys/libkern.h>
#include <sys/module.h>
#include <sys/malloc.h>
#include <sys/bus.h>
#include <sys/random.h>

#include <machine/specialreg.h>

#define	RDRAND_ALIGN(p)	(void *)(roundup2((uintptr_t)(p), 16))


struct rdrand_softc {
	struct callout	sc_rng_co;
	int32_t		sc_rng_ticks;
};


static void rdrand_rng_harvest(void *);
int rdrand_rng(uint8_t *out, int limit);


MALLOC_DEFINE(M_RDRAND, "rdrand_data", "RdRand Data");


static void
rdrand_identify(driver_t *drv, device_t parent)
{

	/* NB: order 10 is so we get attached after h/w devices */
	if (device_find_child(parent, "rdrand", -1) == NULL &&
	    BUS_ADD_CHILD(parent, parent, 10, "rdrand", -1) == 0)
		panic("rdrand: could not attach");
}


static int
rdrand_probe(device_t dev)
{

	if ((cpu_feature2 & CPUID2_RDRAND) == 0) {
		device_printf(dev, "No RdRand support.\n");
		return (EINVAL);
	}

	device_set_desc(dev, "RdRand RNG");
	return 0;
}


static int
rdrand_attach(device_t dev)
{
	struct rdrand_softc *sc;

	sc = device_get_softc(dev);

	if (hz > 100)
		sc->sc_rng_ticks = hz/100;
	else
		sc->sc_rng_ticks = 1;

	callout_init_mp(&sc->sc_rng_co);
	callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks,
	    rdrand_rng_harvest, sc);

	return 0;
}


static int
rdrand_detach(device_t dev)
{
	struct rdrand_softc *sc;

	sc = device_get_softc(dev);

	callout_stop_sync(&sc->sc_rng_co);

	return (0);
}


static int random_count = 512; /* in bytes */

static void
rdrand_rng_harvest(void *arg)
{
	struct rdrand_softc *sc = arg;
	uint8_t randomness[2048];
	uint8_t *arandomness; /* randomness aligned */
	int i, cnt;

	arandomness = RDRAND_ALIGN(randomness);
	cnt = rdrand_rng(arandomness, random_count);

	for (i = 0; i < cnt; i++)
		add_true_randomness((int)arandomness[i]);

	callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks,
	    rdrand_rng_harvest, sc);
}


static device_method_t rdrand_methods[] = {
	DEVMETHOD(device_identify, rdrand_identify),
	DEVMETHOD(device_probe, rdrand_probe),
	DEVMETHOD(device_attach, rdrand_attach),
	DEVMETHOD(device_detach, rdrand_detach),

	{0, 0},
};


static driver_t rdrand_driver = {
	"rdrand",
	rdrand_methods,
	sizeof(struct rdrand_softc),
};

static devclass_t rdrand_devclass;

DRIVER_MODULE(rdrand, nexus, rdrand_driver, rdrand_devclass, NULL, NULL);
MODULE_VERSION(rdrand, 1);
MODULE_DEPEND(rdrand, crypto, 1, 1, 1);