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 37 #include <limits.h> 38 39 #include "util-internal.h" 40 #include "evthread-internal.h" 41 42 #ifdef _EVENT_HAVE_ARC4RANDOM 43 #include <stdlib.h> 44 #include <string.h> 45 int 46 evutil_secure_rng_set_urandom_device_file(char *fname) 47 { 48 (void) fname; 49 return -1; 50 } 51 int 52 evutil_secure_rng_init(void) 53 { 54 /* call arc4random() now to force it to self-initialize */ 55 (void) arc4random(); 56 return 0; 57 } 58 int 59 evutil_secure_rng_global_setup_locks_(const int enable_locks) 60 { 61 return 0; 62 } 63 64 static void 65 ev_arc4random_buf(void *buf, size_t n) 66 { 67 #if defined(_EVENT_HAVE_ARC4RANDOM_BUF) && !defined(__APPLE__) 68 return arc4random_buf(buf, n); 69 #else 70 unsigned char *b = buf; 71 72 #if defined(_EVENT_HAVE_ARC4RANDOM_BUF) 73 /* OSX 10.7 introducd arc4random_buf, so if you build your program 74 * there, you'll get surprised when older versions of OSX fail to run. 75 * To solve this, we can check whether the function pointer is set, 76 * and fall back otherwise. (OSX does this using some linker 77 * trickery.) 78 */ 79 { 80 void (*tptr)(void *,size_t) = 81 (void (*)(void*,size_t))arc4random_buf; 82 if (tptr != NULL) { 83 return arc4random_buf(buf, n); 84 } 85 } 86 #endif 87 /* Make sure that we start out with b at a 4-byte alignment; plenty 88 * of CPUs care about this for 32-bit access. */ 89 if (n >= 4 && ((ev_uintptr_t)b) & 3) { 90 ev_uint32_t u = arc4random(); 91 int n_bytes = 4 - (((ev_uintptr_t)b) & 3); 92 memcpy(b, &u, n_bytes); 93 b += n_bytes; 94 n -= n_bytes; 95 } 96 while (n >= 4) { 97 *(ev_uint32_t*)b = arc4random(); 98 b += 4; 99 n -= 4; 100 } 101 if (n) { 102 ev_uint32_t u = arc4random(); 103 memcpy(b, &u, n); 104 } 105 #endif 106 } 107 108 #else /* !_EVENT_HAVE_ARC4RANDOM { */ 109 110 #ifdef _EVENT_ssize_t 111 #define ssize_t _EVENT_SSIZE_t 112 #endif 113 #define ARC4RANDOM_EXPORT static 114 #define _ARC4_LOCK() EVLOCK_LOCK(arc4rand_lock, 0) 115 #define _ARC4_UNLOCK() EVLOCK_UNLOCK(arc4rand_lock, 0) 116 #ifndef _EVENT_DISABLE_THREAD_SUPPORT 117 static void *arc4rand_lock; 118 #endif 119 120 #define ARC4RANDOM_UINT32 ev_uint32_t 121 #define ARC4RANDOM_NOSTIR 122 #define ARC4RANDOM_NORANDOM 123 #define ARC4RANDOM_NOUNIFORM 124 125 #include "./arc4random.c" 126 127 #ifndef _EVENT_DISABLE_THREAD_SUPPORT 128 int 129 evutil_secure_rng_global_setup_locks_(const int enable_locks) 130 { 131 EVTHREAD_SETUP_GLOBAL_LOCK(arc4rand_lock, 0); 132 return 0; 133 } 134 #endif 135 136 int 137 evutil_secure_rng_set_urandom_device_file(char *fname) 138 { 139 #ifdef TRY_SEED_URANDOM 140 _ARC4_LOCK(); 141 arc4random_urandom_filename = fname; 142 _ARC4_UNLOCK(); 143 #endif 144 return 0; 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 #if !defined(__BIONIC__) /* bionic and OpenBSD removed this; it's a no-op in their current implementation. */ 178 arc4random_addrandom((unsigned char*)buf, 179 n>(size_t)INT_MAX ? INT_MAX : (int)n); 180 #endif 181 } 182 183
