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/*
* 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 (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
*/
#include <sys/types.h>
#include <sys/sysmacros.h>
#include <sys/modctl.h>
#include <sys/conf.h>
#include <sys/devops.h>
#include <sys/cmn_err.h>
#include <sys/kmem.h>
#include <sys/stat.h>
#include <sys/open.h>
#include <sys/file.h>
#include <sys/cpuvar.h>
#include <sys/disp.h>
#include <sys/hsvc.h>
#include <sys/machsystm.h>
#include <sys/ksynch.h>
#include <sys/hypervisor_api.h>
#include <sys/n2rng.h>
#include <sys/sha1.h>
#include <sys/ddi.h> /* near end to get min and max macros right */
#include <sys/sunddi.h>
#include <rng/fips_random.h>
/* n must be a power of 2 */
#define ROUNDUP(k, n) (((k) + (n) - 1) & ~((n) - 1))
/*
* Policy. ENTROPY_STARVATION is the maximum number of calls each
* FIPS instance will accept without successfully getting more
* entropy. It needs to be large enough to allow RNG operations to
* not stall because of health checks, etc. But we don't want it too
* large. FIPS 186-2 change 1 (5 October 2001) states that no more
* that 2,000,000 DSA signatures (done using this algorithm) should be
* done without reseeding. We make sure we add 64 bits of entropy at
* most every 10000 operations, hence we will have stirred in 160 bits
* of entropy at most once every 30000 operations. Normally, we stir
* in 64 bits of entropy for every number generated.
*/
#define ENTROPY_STARVATION 10000ULL
int
fips_random(n2rng_t *n2rng, uint8_t *out, size_t nbytes)
{
int i;
fipsrandomstruct_t *frsp;
int rv;
union {
uint32_t as32[SHA1WORDS];
uint64_t as64[ROUNDUP(SHA1WORDS, 2) >> 1];
} entropy = {0};
uint32_t tempout[SHA1WORDS];
for (i = 0; i < nbytes; i += SHA1BYTES) {
frsp = &n2rng->n_frs.fipsarray[
atomic_inc_32_nv(&n2rng->n_frs.fips_round_robin_j) %
N2RNG_FIPS_INSTANCES];
/*
* Since in the new scheme of things, the RNG latency
* will be high on reads after the first, we get just
* one word of entropy per call.
*/
if ((rv = n2rng_getentropy(n2rng, (void *)&entropy.as64[1],
sizeof (uint64_t))) != 0) {
/*
* If all rngs have failed, dispatch task to unregister
* from kcf and put the driver in an error state. If
* recoverable errors persist, a configuration retry
* will be initiated.
*/
if (rv == EPERM) {
n2rng_failure(n2rng);
return (EIO);
}
/* Failure with possible recovery */
entropy.as64[1] = 0;
}
/*
* The idea here is that a Niagara2 chip is highly
* parallel, with many strands. If we have just one
* instance of the FIPS data, then only one FIPS
* computation can happen at a time, serializeing all
* the RNG stuff. So we make N2RNG_FIPS_INSTANCES,
* and use them round-robin, with the counter being
* n2rng->n_frs.fips_round_robin_j. We increment the
* counter with an atomic op, avoiding having to have
* a global muxtex. The atomic ops are also
* significantly faster than mutexes. The mutex is
* put inside the loop, otherwise one thread reading
* many blocks could stall all other strands.
*/
frsp = &n2rng->n_frs.fipsarray[
atomic_inc_32_nv(&n2rng->n_frs.fips_round_robin_j) %
N2RNG_FIPS_INSTANCES];
mutex_enter(&frsp->mtx);
if (entropy.as64[1] == 0) {
/*
* If we did not get any entropy, entropyword
* is zero. We get a false positive with
* probablitity 2^-64. It's not worth a few
* extra stores and tests eliminate the false
* positive.
*/
if (++frsp->entropyhunger > ENTROPY_STARVATION) {
mutex_exit(&frsp->mtx);
n2rng_unconfigured(n2rng);
return (EIO);
}
} else {
frsp->entropyhunger = 0;
}
/* nbytes - i is bytes to go */
fips_random_inner(frsp->XKEY, tempout, entropy.as32);
bcopy(tempout, &out[i], min(nbytes - i, SHA1BYTES));
mutex_exit(&frsp->mtx);
}
/* Zeroize sensitive information */
entropy.as64[1] = 0;
bzero(tempout, SHA1BYTES);
return (0);
}
/*
* Initializes one FIPS RNG instance. Must be called once for each
* instance.
*/
int
n2rng_fips_random_init(n2rng_t *n2rng, fipsrandomstruct_t *frsp)
{
/*
* All FIPS-approved algorithms will operate as cryptograpic
* quality PRNGs even if there is no entropy source. (In
* fact, this the only one that accepts entropy on the fly.)
* One motivation for this is that they system keeps on
* delivering cryptographic quality random numbers, even if
* the entropy source fails.
*/
int rv;
static uint32_t FIPS_RNG_NO_USER_INPUT[] = {0, 0, 0, 0, 0};
rv = n2rng_getentropy(n2rng, (void *)frsp->XKEY, ROUNDUP(SHA1BYTES, 8));
if (rv) {
return (rv);
}
frsp->entropyhunger = 0;
mutex_init(&frsp->mtx, NULL, MUTEX_DRIVER, NULL);
/* compute the first (compare only) random value */
fips_random_inner(frsp->XKEY, frsp->x_jminus1, FIPS_RNG_NO_USER_INPUT);
return (0);
}
void
n2rng_fips_random_fini(fipsrandomstruct_t *frsp)
{
mutex_destroy(&frsp->mtx);
/*
* Zeroise fips data. Not really necessary, since the
* algorithm has backtracking resistance, but do it anyway.
*/
bzero(frsp, sizeof (fipsrandomstruct_t));
}
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