1 /* $NetBSD: evutil_rand.c,v 1.6 2021/04/07 03:36:48 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 <sys/cdefs.h> 39 __RCSID("$NetBSD: evutil_rand.c,v 1.6 2021/04/07 03:36:48 christos Exp $"); 40 #include "evconfig-private.h" 41 42 #include <limits.h> 43 44 #include "util-internal.h" 45 #include "evthread-internal.h" 46 47 #ifdef EVENT__HAVE_ARC4RANDOM 48 #include <stdlib.h> 49 #include <string.h> 50 int 51 evutil_secure_rng_set_urandom_device_file(char *fname) 52 { 53 (void) fname; 54 return -1; 55 } 56 int 57 evutil_secure_rng_init(void) 58 { 59 /* call arc4random() now to force it to self-initialize */ 60 (void) arc4random(); 61 return 0; 62 } 63 #ifndef EVENT__DISABLE_THREAD_SUPPORT 64 int 65 /*ARGSUSED*/ 66 evutil_secure_rng_global_setup_locks_(const int enable_locks) 67 { 68 return 0; 69 } 70 #endif 71 static void 72 evutil_free_secure_rng_globals_locks(void) 73 { 74 } 75 76 static void 77 /*ARGSUSED*/ 78 ev_arc4random_buf(void *buf, size_t n) 79 { 80 #if defined(EVENT__HAVE_ARC4RANDOM_BUF) && !defined(__APPLE__) 81 arc4random_buf(buf, n); 82 return; 83 #else 84 unsigned char *b = buf; 85 86 #if defined(EVENT__HAVE_ARC4RANDOM_BUF) 87 /* OSX 10.7 introducd arc4random_buf, so if you build your program 88 * there, you'll get surprised when older versions of OSX fail to run. 89 * To solve this, we can check whether the function pointer is set, 90 * and fall back otherwise. (OSX does this using some linker 91 * trickery.) 92 */ 93 { 94 void (*tptr)(void *,size_t) = 95 (void (*)(void*,size_t))arc4random_buf; 96 if (tptr != NULL) { 97 arc4random_buf(buf, n); 98 return; 99 } 100 } 101 #endif 102 /* Make sure that we start out with b at a 4-byte alignment; plenty 103 * of CPUs care about this for 32-bit access. */ 104 if (n >= 4 && ((ev_uintptr_t)b) & 3) { 105 ev_uint32_t u = arc4random(); 106 int n_bytes = 4 - (((ev_uintptr_t)b) & 3); 107 memcpy(b, &u, n_bytes); 108 b += n_bytes; 109 n -= n_bytes; 110 } 111 while (n >= 4) { 112 *(ev_uint32_t*)b = arc4random(); 113 b += 4; 114 n -= 4; 115 } 116 if (n) { 117 ev_uint32_t u = arc4random(); 118 memcpy(b, &u, n); 119 } 120 #endif 121 } 122 123 #else /* !EVENT__HAVE_ARC4RANDOM { */ 124 125 #ifdef EVENT__ssize_t 126 #define ssize_t EVENT__ssize_t 127 #endif 128 #define ARC4RANDOM_EXPORT static 129 #define ARC4_LOCK_() EVLOCK_LOCK(arc4rand_lock, 0) 130 #define ARC4_UNLOCK_() EVLOCK_UNLOCK(arc4rand_lock, 0) 131 #ifndef EVENT__DISABLE_THREAD_SUPPORT 132 static void *arc4rand_lock; 133 #endif 134 135 #define ARC4RANDOM_UINT32 ev_uint32_t 136 #define ARC4RANDOM_NOSTIR 137 #define ARC4RANDOM_NORANDOM 138 #define ARC4RANDOM_NOUNIFORM 139 140 #include "./arc4random.c" 141 142 #ifndef EVENT__DISABLE_THREAD_SUPPORT 143 int 144 evutil_secure_rng_global_setup_locks_(const int enable_locks) 145 { 146 EVTHREAD_SETUP_GLOBAL_LOCK(arc4rand_lock, 0); 147 return 0; 148 } 149 #endif 150 151 static void 152 evutil_free_secure_rng_globals_locks(void) 153 { 154 #ifndef EVENT__DISABLE_THREAD_SUPPORT 155 if (arc4rand_lock != NULL) { 156 EVTHREAD_FREE_LOCK(arc4rand_lock, 0); 157 arc4rand_lock = NULL; 158 } 159 #endif 160 return; 161 } 162 163 int 164 /*ARGSUSED*/ 165 evutil_secure_rng_set_urandom_device_file(char *fname) 166 { 167 #ifdef TRY_SEED_URANDOM 168 ARC4_LOCK_(); 169 arc4random_urandom_filename = fname; 170 ARC4_UNLOCK_(); 171 #endif 172 return 0; 173 } 174 175 int 176 evutil_secure_rng_init(void) 177 { 178 int val; 179 180 ARC4_LOCK_(); 181 val = (!arc4_stir()) ? 0 : -1; 182 ARC4_UNLOCK_(); 183 return val; 184 } 185 186 static void 187 ev_arc4random_buf(void *buf, size_t n) 188 { 189 arc4random_buf(buf, n); 190 } 191 192 #endif /* } !EVENT__HAVE_ARC4RANDOM */ 193 194 void 195 evutil_secure_rng_get_bytes(void *buf, size_t n) 196 { 197 ev_arc4random_buf(buf, n); 198 } 199 200 #if !defined(EVENT__HAVE_ARC4RANDOM) || defined(EVENT__HAVE_ARC4RANDOM_ADDRANDOM) 201 void 202 evutil_secure_rng_add_bytes(const char *buf, size_t n) 203 { 204 arc4random_addrandom(__UNCONST(buf), 205 n>(size_t)INT_MAX ? INT_MAX : (int)n); 206 } 207 #endif 208 209 void 210 evutil_free_secure_rng_globals_(void) 211 { 212 evutil_free_secure_rng_globals_locks(); 213 } 214