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 #endif 72 73 /** 74 * Max random value. Similar to RAND_MAX, but more portable 75 * (mingw uses only 15 bits random). 76 */ 77 #define MAX_VALUE 0x7fffffff 78 79 #ifndef HAVE_NSS 80 void 81 ub_systemseed(unsigned int ATTR_UNUSED(seed)) 82 { 83 /* arc4random_uniform does not need seeds, it gets kernel entropy */ 84 } 85 86 struct ub_randstate* 87 ub_initstate(unsigned int ATTR_UNUSED(seed), 88 struct ub_randstate* ATTR_UNUSED(from)) 89 { 90 struct ub_randstate* s = (struct ub_randstate*)malloc(1); 91 if(!s) { 92 log_err("malloc failure in random init"); 93 return NULL; 94 } 95 return s; 96 } 97 98 long int 99 ub_random(struct ub_randstate* ATTR_UNUSED(s)) 100 { 101 /* This relies on MAX_VALUE being 0x7fffffff. */ 102 return (long)arc4random() & MAX_VALUE; 103 } 104 105 long int 106 ub_random_max(struct ub_randstate* state, long int x) 107 { 108 (void)state; 109 /* on OpenBSD, this does not need _seed(), or _stir() calls */ 110 return (long)arc4random_uniform((uint32_t)x); 111 } 112 113 #else 114 115 /* not much to remember for NSS since we use its pk11_random, placeholder */ 116 struct ub_randstate { 117 int ready; 118 }; 119 120 void ub_systemseed(unsigned int ATTR_UNUSED(seed)) 121 { 122 } 123 124 struct ub_randstate* ub_initstate(unsigned int ATTR_UNUSED(seed), 125 struct ub_randstate* ATTR_UNUSED(from)) 126 { 127 struct ub_randstate* s = (struct ub_randstate*)calloc(1, sizeof(*s)); 128 if(!s) { 129 log_err("malloc failure in random init"); 130 return NULL; 131 } 132 return s; 133 } 134 135 long int ub_random(struct ub_randstate* ATTR_UNUSED(state)) 136 { 137 long int x; 138 /* random 31 bit value. */ 139 SECStatus s = PK11_GenerateRandom((unsigned char*)&x, (int)sizeof(x)); 140 if(s != SECSuccess) { 141 log_err("PK11_GenerateRandom error: %s", 142 PORT_ErrorToString(PORT_GetError())); 143 } 144 return x & MAX_VALUE; 145 } 146 147 long int 148 ub_random_max(struct ub_randstate* state, long int x) 149 { 150 /* make sure we fetch in a range that is divisible by x. ignore 151 * values from d .. MAX_VALUE, instead draw a new number */ 152 long int d = MAX_VALUE - (MAX_VALUE % x); /* d is divisible by x */ 153 long int v = ub_random(state); 154 while(d <= v) 155 v = ub_random(state); 156 return (v % x); 157 } 158 #endif /* HAVE_NSS */ 159 160 void 161 ub_randfree(struct ub_randstate* s) 162 { 163 if(s) 164 free(s); 165 /* user app must do RAND_cleanup(); */ 166 } 167