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