1 /* $NetBSD: evutil_rand.c,v 1.1.1.1 2013/12/27 23:31:19 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_init(void) 50 { 51 /* call arc4random() now to force it to self-initialize */ 52 (void) arc4random(); 53 return 0; 54 } 55 #ifndef EVENT__DISABLE_THREAD_SUPPORT 56 int 57 evutil_secure_rng_global_setup_locks_(const int enable_locks) 58 { 59 return 0; 60 } 61 #endif 62 static void 63 evutil_free_secure_rng_globals_locks(void) 64 { 65 } 66 67 static void 68 ev_arc4random_buf(void *buf, size_t n) 69 { 70 #if defined(EVENT__HAVE_ARC4RANDOM_BUF) && !defined(__APPLE__) 71 return arc4random_buf(buf, n); 72 #else 73 unsigned char *b = buf; 74 75 #if defined(EVENT__HAVE_ARC4RANDOM_BUF) 76 /* OSX 10.7 introducd arc4random_buf, so if you build your program 77 * there, you'll get surprised when older versions of OSX fail to run. 78 * To solve this, we can check whether the function pointer is set, 79 * and fall back otherwise. (OSX does this using some linker 80 * trickery.) 81 */ 82 if (arc4random_buf != NULL) { 83 return arc4random_buf(buf, n); 84 } 85 #endif 86 /* Make sure that we start out with b at a 4-byte alignment; plenty 87 * of CPUs care about this for 32-bit access. */ 88 if (n >= 4 && ((ev_uintptr_t)b) & 3) { 89 ev_uint32_t u = arc4random(); 90 int n_bytes = 4 - (((ev_uintptr_t)b) & 3); 91 memcpy(b, &u, n_bytes); 92 b += n_bytes; 93 n -= n_bytes; 94 } 95 while (n >= 4) { 96 *(ev_uint32_t*)b = arc4random(); 97 b += 4; 98 n -= 4; 99 } 100 if (n) { 101 ev_uint32_t u = arc4random(); 102 memcpy(b, &u, n); 103 } 104 #endif 105 } 106 107 #else /* !EVENT__HAVE_ARC4RANDOM { */ 108 109 #ifdef EVENT__ssize_t 110 #define ssize_t EVENT__ssize_t 111 #endif 112 #define ARC4RANDOM_EXPORT static 113 #define ARC4_LOCK_() EVLOCK_LOCK(arc4rand_lock, 0) 114 #define ARC4_UNLOCK_() EVLOCK_UNLOCK(arc4rand_lock, 0) 115 #ifndef EVENT__DISABLE_THREAD_SUPPORT 116 static void *arc4rand_lock; 117 #endif 118 119 #define ARC4RANDOM_UINT32 ev_uint32_t 120 #define ARC4RANDOM_NOSTIR 121 #define ARC4RANDOM_NORANDOM 122 #define ARC4RANDOM_NOUNIFORM 123 124 #include "./arc4random.c" 125 126 #ifndef EVENT__DISABLE_THREAD_SUPPORT 127 int 128 evutil_secure_rng_global_setup_locks_(const int enable_locks) 129 { 130 EVTHREAD_SETUP_GLOBAL_LOCK(arc4rand_lock, 0); 131 return 0; 132 } 133 #endif 134 135 static void 136 evutil_free_secure_rng_globals_locks(void) 137 { 138 #ifndef EVENT__DISABLE_THREAD_SUPPORT 139 if (arc4rand_lock != NULL) { 140 EVTHREAD_FREE_LOCK(arc4rand_lock, 0); 141 arc4rand_lock = NULL; 142 } 143 #endif 144 return; 145 } 146 147 int 148 evutil_secure_rng_init(void) 149 { 150 int val; 151 152 ARC4_LOCK_(); 153 if (!arc4_seeded_ok) 154 arc4_stir(); 155 val = arc4_seeded_ok ? 0 : -1; 156 ARC4_UNLOCK_(); 157 return val; 158 } 159 160 static void 161 ev_arc4random_buf(void *buf, size_t n) 162 { 163 arc4random_buf(buf, n); 164 } 165 166 #endif /* } !EVENT__HAVE_ARC4RANDOM */ 167 168 void 169 evutil_secure_rng_get_bytes(void *buf, size_t n) 170 { 171 ev_arc4random_buf(buf, n); 172 } 173 174 void 175 evutil_secure_rng_add_bytes(const char *buf, size_t n) 176 { 177 arc4random_addrandom((unsigned char*)buf, 178 n>(size_t)INT_MAX ? INT_MAX : (int)n); 179 } 180 181 void 182 evutil_free_secure_rng_globals_(void) 183 { 184 evutil_free_secure_rng_globals_locks(); 185 } 186