1 /* $NetBSD: evutil_rand.c,v 1.4 2016/01/08 21:35:40 christos Exp $ */ 2 3 /* 4 * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /* This file has our secure PRNG code. On platforms that have arc4random(), 30 * we just use that. Otherwise, we include arc4random.c as a bunch of static 31 * functions, and wrap it lightly. We don't expose the arc4random*() APIs 32 * because A) they aren't in our namespace, and B) it's not nice to name your 33 * APIs after their implementations. We keep them in a separate file 34 * so that other people can rip it out and use it for whatever. 35 */ 36 37 #include "event2/event-config.h" 38 #include "evconfig-private.h" 39 40 #include <limits.h> 41 42 #include "util-internal.h" 43 #include "evthread-internal.h" 44 45 #ifdef EVENT__HAVE_ARC4RANDOM 46 #include <stdlib.h> 47 #include <string.h> 48 int 49 evutil_secure_rng_set_urandom_device_file(char *fname) 50 { 51 (void) fname; 52 return -1; 53 } 54 int 55 evutil_secure_rng_init(void) 56 { 57 /* call arc4random() now to force it to self-initialize */ 58 (void) arc4random(); 59 return 0; 60 } 61 #ifndef EVENT__DISABLE_THREAD_SUPPORT 62 int 63 evutil_secure_rng_global_setup_locks_(const int enable_locks) 64 { 65 return 0; 66 } 67 #endif 68 static void 69 evutil_free_secure_rng_globals_locks(void) 70 { 71 } 72 73 static void 74 ev_arc4random_buf(void *buf, size_t n) 75 { 76 #if defined(EVENT__HAVE_ARC4RANDOM_BUF) && !defined(__APPLE__) 77 arc4random_buf(buf, n); 78 return; 79 #else 80 unsigned char *b = buf; 81 82 #if defined(EVENT__HAVE_ARC4RANDOM_BUF) 83 /* OSX 10.7 introducd arc4random_buf, so if you build your program 84 * there, you'll get surprised when older versions of OSX fail to run. 85 * To solve this, we can check whether the function pointer is set, 86 * and fall back otherwise. (OSX does this using some linker 87 * trickery.) 88 */ 89 { 90 void (*tptr)(void *,size_t) = 91 (void (*)(void*,size_t))arc4random_buf; 92 if (tptr != NULL) { 93 arc4random_buf(buf, n); 94 return; 95 } 96 } 97 #endif 98 /* Make sure that we start out with b at a 4-byte alignment; plenty 99 * of CPUs care about this for 32-bit access. */ 100 if (n >= 4 && ((ev_uintptr_t)b) & 3) { 101 ev_uint32_t u = arc4random(); 102 int n_bytes = 4 - (((ev_uintptr_t)b) & 3); 103 memcpy(b, &u, n_bytes); 104 b += n_bytes; 105 n -= n_bytes; 106 } 107 while (n >= 4) { 108 *(ev_uint32_t*)b = arc4random(); 109 b += 4; 110 n -= 4; 111 } 112 if (n) { 113 ev_uint32_t u = arc4random(); 114 memcpy(b, &u, n); 115 } 116 #endif 117 } 118 119 #else /* !EVENT__HAVE_ARC4RANDOM { */ 120 121 #ifdef EVENT__ssize_t 122 #define ssize_t EVENT__ssize_t 123 #endif 124 #define ARC4RANDOM_EXPORT static 125 #define ARC4_LOCK_() EVLOCK_LOCK(arc4rand_lock, 0) 126 #define ARC4_UNLOCK_() EVLOCK_UNLOCK(arc4rand_lock, 0) 127 #ifndef EVENT__DISABLE_THREAD_SUPPORT 128 static void *arc4rand_lock; 129 #endif 130 131 #define ARC4RANDOM_UINT32 ev_uint32_t 132 #define ARC4RANDOM_NOSTIR 133 #define ARC4RANDOM_NORANDOM 134 #define ARC4RANDOM_NOUNIFORM 135 136 #include "./arc4random.c" 137 138 #ifndef EVENT__DISABLE_THREAD_SUPPORT 139 int 140 evutil_secure_rng_global_setup_locks_(const int enable_locks) 141 { 142 EVTHREAD_SETUP_GLOBAL_LOCK(arc4rand_lock, 0); 143 return 0; 144 } 145 #endif 146 147 static void 148 evutil_free_secure_rng_globals_locks(void) 149 { 150 #ifndef EVENT__DISABLE_THREAD_SUPPORT 151 if (arc4rand_lock != NULL) { 152 EVTHREAD_FREE_LOCK(arc4rand_lock, 0); 153 arc4rand_lock = NULL; 154 } 155 #endif 156 return; 157 } 158 159 int 160 evutil_secure_rng_set_urandom_device_file(char *fname) 161 { 162 #ifdef TRY_SEED_URANDOM 163 ARC4_LOCK_(); 164 arc4random_urandom_filename = fname; 165 ARC4_UNLOCK_(); 166 #endif 167 return 0; 168 } 169 170 int 171 evutil_secure_rng_init(void) 172 { 173 int val; 174 175 ARC4_LOCK_(); 176 if (!arc4_seeded_ok) 177 arc4_stir(); 178 val = arc4_seeded_ok ? 0 : -1; 179 ARC4_UNLOCK_(); 180 return val; 181 } 182 183 static void 184 ev_arc4random_buf(void *buf, size_t n) 185 { 186 arc4random_buf(buf, n); 187 } 188 189 #endif /* } !EVENT__HAVE_ARC4RANDOM */ 190 191 void 192 evutil_secure_rng_get_bytes(void *buf, size_t n) 193 { 194 ev_arc4random_buf(buf, n); 195 } 196 197 void 198 evutil_secure_rng_add_bytes(const char *buf, size_t n) 199 { 200 arc4random_addrandom((unsigned char*)buf, 201 n>(size_t)INT_MAX ? INT_MAX : (int)n); 202 } 203 204 void 205 evutil_free_secure_rng_globals_(void) 206 { 207 evutil_free_secure_rng_globals_locks(); 208 } 209