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* 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 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 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 }; 114 115 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 } 124 125 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 }; 149 150 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 } 174 175 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 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 204 ub_randfree(struct ub_randstate* s) 205 { 206 free(s); 207 /* user app must do RAND_cleanup(); */ 208 } 209