1 /*
2 * util/random.c - thread safe random generator, which is reasonably secure.
3 *
4 * Copyright (c) 2007, NLnet Labs. All rights reserved.
5 *
6 * This software is open source.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * Redistributions of source code must retain the above copyright notice,
13 * this list of conditions and the following disclaimer.
14 *
15 * Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
18 *
19 * Neither the name of the NLNET LABS nor the names of its contributors may
20 * be used to endorse or promote products derived from this software without
21 * specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
29 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
30 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
31 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
32 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36 /**
37 * \file
38 * Thread safe random functions. Similar to arc4random() with an explicit
39 * initialisation routine.
40 *
41 * The code in this file is based on arc4random from
42 * openssh-4.0p1/openbsd-compat/bsd-arc4random.c
43 * That code is also BSD licensed. Here is their statement:
44 *
45 * Copyright (c) 1996, David Mazieres <dm@uun.org>
46 * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
47 *
48 * Permission to use, copy, modify, and distribute this software for any
49 * purpose with or without fee is hereby granted, provided that the above
50 * copyright notice and this permission notice appear in all copies.
51 *
52 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
53 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
54 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
55 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
56 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
57 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
58 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
59 */
60 #include "config.h"
61 #include "util/random.h"
62 #include "util/log.h"
63 #include <time.h>
64
65 #ifdef HAVE_NSS
66 /* nspr4 */
67 #include "prerror.h"
68 /* nss3 */
69 #include "secport.h"
70 #include "pk11pub.h"
71 #elif defined(HAVE_NETTLE)
72 #include "yarrow.h"
73 #endif
74
75 /**
76 * Max random value. Similar to RAND_MAX, but more portable
77 * (mingw uses only 15 bits random).
78 */
79 #define MAX_VALUE 0x7fffffff
80
81 #if defined(HAVE_SSL) || defined(HAVE_LIBBSD)
82 struct ub_randstate*
ub_initstate(struct ub_randstate * ATTR_UNUSED (from))83 ub_initstate(struct ub_randstate* ATTR_UNUSED(from))
84 {
85 struct ub_randstate* s = (struct ub_randstate*)malloc(1);
86 if(!s) {
87 log_err("malloc failure in random init");
88 return NULL;
89 }
90 return s;
91 }
92
93 long int
ub_random(struct ub_randstate * ATTR_UNUSED (s))94 ub_random(struct ub_randstate* ATTR_UNUSED(s))
95 {
96 /* This relies on MAX_VALUE being 0x7fffffff. */
97 return (long)arc4random() & MAX_VALUE;
98 }
99
100 long int
ub_random_max(struct ub_randstate * state,long int x)101 ub_random_max(struct ub_randstate* state, long int x)
102 {
103 (void)state;
104 /* on OpenBSD, this does not need _seed(), or _stir() calls */
105 return (long)arc4random_uniform((uint32_t)x);
106 }
107
108 #elif defined(HAVE_NSS)
109
110 /* not much to remember for NSS since we use its pk11_random, placeholder */
111 struct ub_randstate {
112 int ready;
113 };
114
ub_initstate(struct ub_randstate * ATTR_UNUSED (from))115 struct ub_randstate* ub_initstate(struct ub_randstate* ATTR_UNUSED(from))
116 {
117 struct ub_randstate* s = (struct ub_randstate*)calloc(1, sizeof(*s));
118 if(!s) {
119 log_err("malloc failure in random init");
120 return NULL;
121 }
122 return s;
123 }
124
ub_random(struct ub_randstate * ATTR_UNUSED (state))125 long int ub_random(struct ub_randstate* ATTR_UNUSED(state))
126 {
127 long int x;
128 /* random 31 bit value. */
129 SECStatus s = PK11_GenerateRandom((unsigned char*)&x, (int)sizeof(x));
130 if(s != SECSuccess) {
131 /* unbound needs secure randomness for randomized
132 * ID bits and port numbers in packets to upstream servers */
133 fatal_exit("PK11_GenerateRandom error: %s",
134 PORT_ErrorToString(PORT_GetError()));
135 }
136 return x & MAX_VALUE;
137 }
138
139 #elif defined(HAVE_NETTLE)
140
141 /**
142 * libnettle implements a Yarrow-256 generator (SHA256 + AES),
143 * and we have to ensure it is seeded before use.
144 */
145 struct ub_randstate {
146 struct yarrow256_ctx ctx;
147 int seeded;
148 };
149
ub_initstate(struct ub_randstate * ATTR_UNUSED (from))150 struct ub_randstate* ub_initstate(struct ub_randstate* ATTR_UNUSED(from))
151 {
152 struct ub_randstate* s = (struct ub_randstate*)calloc(1, sizeof(*s));
153 uint8_t buf[YARROW256_SEED_FILE_SIZE];
154 if(!s) {
155 log_err("malloc failure in random init");
156 return NULL;
157 }
158 /* Setup Yarrow context */
159 yarrow256_init(&s->ctx, 0, NULL);
160
161 if(getentropy(buf, sizeof(buf)) != -1) {
162 /* got entropy */
163 yarrow256_seed(&s->ctx, YARROW256_SEED_FILE_SIZE, buf);
164 s->seeded = yarrow256_is_seeded(&s->ctx);
165 } else {
166 log_err("nettle random(yarrow) cannot initialize, "
167 "getentropy failed: %s", strerror(errno));
168 free(s);
169 return NULL;
170 }
171
172 return s;
173 }
174
ub_random(struct ub_randstate * s)175 long int ub_random(struct ub_randstate* s)
176 {
177 /* random 31 bit value. */
178 long int x = 0;
179 if (!s || !s->seeded) {
180 log_err("Couldn't generate randomness, Yarrow-256 generator not yet seeded");
181 } else {
182 yarrow256_random(&s->ctx, sizeof(x), (uint8_t *)&x);
183 }
184 return x & MAX_VALUE;
185 }
186 #endif /* HAVE_SSL or HAVE_LIBBSD or HAVE_NSS or HAVE_NETTLE */
187
188
189 #if defined(HAVE_NSS) || defined(HAVE_NETTLE) && !defined(HAVE_LIBBSD)
190 long int
ub_random_max(struct ub_randstate * state,long int x)191 ub_random_max(struct ub_randstate* state, long int x)
192 {
193 /* make sure we fetch in a range that is divisible by x. ignore
194 * values from d .. MAX_VALUE, instead draw a new number */
195 long int d = MAX_VALUE - (MAX_VALUE % x); /* d is divisible by x */
196 long int v = ub_random(state);
197 while(d <= v)
198 v = ub_random(state);
199 return (v % x);
200 }
201 #endif /* HAVE_NSS or HAVE_NETTLE and !HAVE_LIBBSD */
202
203 void
ub_randfree(struct ub_randstate * s)204 ub_randfree(struct ub_randstate* s)
205 {
206 free(s);
207 /* user app must do RAND_cleanup(); */
208 }
209