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
evutil_secure_rng_set_urandom_device_file(char * fname)51 evutil_secure_rng_set_urandom_device_file(char *fname)
52 {
53 (void) fname;
54 return -1;
55 }
56 int
evutil_secure_rng_init(void)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*/
evutil_secure_rng_global_setup_locks_(const int enable_locks)66 evutil_secure_rng_global_setup_locks_(const int enable_locks)
67 {
68 return 0;
69 }
70 #endif
71 static void
evutil_free_secure_rng_globals_locks(void)72 evutil_free_secure_rng_globals_locks(void)
73 {
74 }
75
76 static void
77 /*ARGSUSED*/
ev_arc4random_buf(void * buf,size_t n)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
evutil_secure_rng_global_setup_locks_(const int enable_locks)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
evutil_free_secure_rng_globals_locks(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*/
evutil_secure_rng_set_urandom_device_file(char * fname)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
evutil_secure_rng_init(void)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
ev_arc4random_buf(void * buf,size_t n)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
evutil_secure_rng_get_bytes(void * buf,size_t n)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
evutil_secure_rng_add_bytes(const char * buf,size_t n)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
evutil_free_secure_rng_globals_(void)210 evutil_free_secure_rng_globals_(void)
211 {
212 evutil_free_secure_rng_globals_locks();
213 }
214