1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
23 */
24
25#include <sys/types.h>
26#include <sys/sysmacros.h>
27#include <sys/modctl.h>
28#include <sys/conf.h>
29#include <sys/devops.h>
30#include <sys/cmn_err.h>
31#include <sys/kmem.h>
32#include <sys/stat.h>
33#include <sys/open.h>
34#include <sys/file.h>
35#include <sys/cpuvar.h>
36#include <sys/disp.h>
37#include <sys/hsvc.h>
38#include <sys/machsystm.h>
39#include <sys/ksynch.h>
40#include <sys/hypervisor_api.h>
41#include <sys/n2rng.h>
42#include <sys/sha1.h>
43#include <sys/ddi.h>  /* near end to get min and max macros right */
44#include <sys/sunddi.h>
45#include <rng/fips_random.h>
46
47/* n must be a power of 2 */
48#define	ROUNDUP(k, n)		(((k) + (n) - 1) & ~((n) - 1))
49
50/*
51 * Policy.  ENTROPY_STARVATION is the maximum number of calls each
52 * FIPS instance will accept without successfully getting more
53 * entropy.  It needs to be large enough to allow RNG operations to
54 * not stall because of health checks, etc.  But we don't want it too
55 * large.  FIPS 186-2 change 1 (5 October 2001) states that no more
56 * that 2,000,000 DSA signatures (done using this algorithm) should be
57 * done without reseeding.  We make sure we add 64 bits of entropy at
58 * most every 10000 operations, hence we will have stirred in 160 bits
59 * of entropy at most once every 30000 operations.  Normally, we stir
60 * in 64 bits of entropy for every number generated.
61 */
62#define	ENTROPY_STARVATION	10000ULL
63
64
65int
66fips_random(n2rng_t *n2rng, uint8_t *out, size_t nbytes)
67{
68	int			i;
69	fipsrandomstruct_t	*frsp;
70	int			rv;
71	union {
72		uint32_t	as32[SHA1WORDS];
73		uint64_t	as64[ROUNDUP(SHA1WORDS, 2) >> 1];
74	} entropy = {0};
75	uint32_t		tempout[SHA1WORDS];
76
77
78	for (i = 0; i < nbytes; i += SHA1BYTES) {
79		frsp = &n2rng->n_frs.fipsarray[
80		    atomic_inc_32_nv(&n2rng->n_frs.fips_round_robin_j) %
81		    N2RNG_FIPS_INSTANCES];
82		/*
83		 * Since in the new scheme of things, the RNG latency
84		 * will be high on reads after the first, we get just
85		 * one word of entropy per call.
86		 */
87		if ((rv = n2rng_getentropy(n2rng, (void *)&entropy.as64[1],
88		    sizeof (uint64_t))) != 0) {
89
90			/*
91			 * If all rngs have failed, dispatch task to unregister
92			 * from kcf and put the driver in an error state.  If
93			 * recoverable errors persist, a configuration retry
94			 * will be initiated.
95			 */
96			if (rv == EPERM) {
97				n2rng_failure(n2rng);
98				return (EIO);
99			}
100			/* Failure with possible recovery */
101			entropy.as64[1] = 0;
102		}
103
104		/*
105		 * The idea here is that a Niagara2 chip is highly
106		 * parallel, with many strands.  If we have just one
107		 * instance of the FIPS data, then only one FIPS
108		 * computation can happen at a time, serializeing all
109		 * the RNG stuff.  So we make N2RNG_FIPS_INSTANCES,
110		 * and use them round-robin, with the counter being
111		 * n2rng->n_frs.fips_round_robin_j.  We increment the
112		 * counter with an atomic op, avoiding having to have
113		 * a global muxtex.  The atomic ops are also
114		 * significantly faster than mutexes.  The mutex is
115		 * put inside the loop, otherwise one thread reading
116		 * many blocks could stall all other strands.
117		 */
118		frsp = &n2rng->n_frs.fipsarray[
119		    atomic_inc_32_nv(&n2rng->n_frs.fips_round_robin_j) %
120		    N2RNG_FIPS_INSTANCES];
121
122		mutex_enter(&frsp->mtx);
123
124		if (entropy.as64[1] == 0) {
125			/*
126			 * If we did not get any entropy, entropyword
127			 * is zero.  We get a false positive with
128			 * probablitity 2^-64.  It's not worth a few
129			 * extra stores and tests eliminate the false
130			 * positive.
131			 */
132			if (++frsp->entropyhunger > ENTROPY_STARVATION) {
133				mutex_exit(&frsp->mtx);
134				n2rng_unconfigured(n2rng);
135				return (EIO);
136			}
137		} else {
138			frsp->entropyhunger = 0;
139		}
140
141		/* nbytes - i is bytes to go */
142		fips_random_inner(frsp->XKEY, tempout, entropy.as32);
143
144		bcopy(tempout, &out[i], min(nbytes - i, SHA1BYTES));
145
146		mutex_exit(&frsp->mtx);
147	}
148
149	/* Zeroize sensitive information */
150
151	entropy.as64[1] = 0;
152	bzero(tempout, SHA1BYTES);
153
154	return (0);
155}
156
157/*
158 * Initializes one FIPS RNG instance.  Must be called once for each
159 * instance.
160 */
161int
162n2rng_fips_random_init(n2rng_t *n2rng, fipsrandomstruct_t *frsp)
163{
164	/*
165	 * All FIPS-approved algorithms will operate as cryptograpic
166	 * quality PRNGs even if there is no entropy source.  (In
167	 * fact, this the only one that accepts entropy on the fly.)
168	 * One motivation for this is that they system keeps on
169	 * delivering cryptographic quality random numbers, even if
170	 * the entropy source fails.
171	 */
172
173	int rv;
174	static uint32_t FIPS_RNG_NO_USER_INPUT[] = {0, 0, 0, 0, 0};
175
176	rv = n2rng_getentropy(n2rng, (void *)frsp->XKEY, ROUNDUP(SHA1BYTES, 8));
177	if (rv) {
178		return (rv);
179	}
180	frsp->entropyhunger = 0;
181	mutex_init(&frsp->mtx, NULL, MUTEX_DRIVER, NULL);
182
183	/* compute the first (compare only) random value */
184	fips_random_inner(frsp->XKEY, frsp->x_jminus1, FIPS_RNG_NO_USER_INPUT);
185
186	return (0);
187}
188
189void
190n2rng_fips_random_fini(fipsrandomstruct_t *frsp)
191{
192	mutex_destroy(&frsp->mtx);
193	/*
194	 * Zeroise fips data.  Not really necessary, since the
195	 * algorithm has backtracking resistance, but do it anyway.
196	 */
197	bzero(frsp, sizeof (fipsrandomstruct_t));
198}
199