1 /* Copyright 2016 The BoringSSL Authors
2 *
3 * Permission to use, copy, modify, and/or distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
14
15 #include <openssl/rand.h>
16
17 #include "../bcm_support.h"
18 #include "sysrand_internal.h"
19
20 #if defined(OPENSSL_RAND_DETERMINISTIC)
21
22 #include <string.h>
23
24 #include <openssl/chacha.h>
25
26 #include "../internal.h"
27
28
29 // g_num_calls is the number of calls to |CRYPTO_sysrand| that have occurred.
30 //
31 // This is intentionally not thread-safe. If the fuzzer mode is ever used in a
32 // multi-threaded program, replace this with a thread-local. (A mutex would not
33 // be deterministic.)
34 static uint64_t g_num_calls = 0;
35 static CRYPTO_MUTEX g_num_calls_lock = CRYPTO_MUTEX_INIT;
36
RAND_reset_for_fuzzing(void)37 void RAND_reset_for_fuzzing(void) { g_num_calls = 0; }
38
CRYPTO_init_sysrand(void)39 void CRYPTO_init_sysrand(void) {}
40
CRYPTO_sysrand(uint8_t * out,size_t requested)41 void CRYPTO_sysrand(uint8_t *out, size_t requested) {
42 static const uint8_t kZeroKey[32] = {0};
43
44 CRYPTO_MUTEX_lock_write(&g_num_calls_lock);
45 uint64_t num_calls = g_num_calls++;
46 CRYPTO_MUTEX_unlock_write(&g_num_calls_lock);
47
48 uint8_t nonce[12];
49 OPENSSL_memset(nonce, 0, sizeof(nonce));
50 OPENSSL_memcpy(nonce, &num_calls, sizeof(num_calls));
51
52 OPENSSL_memset(out, 0, requested);
53 CRYPTO_chacha_20(out, out, requested, kZeroKey, nonce, 0);
54 }
55
CRYPTO_sysrand_if_available(uint8_t * buf,size_t len)56 int CRYPTO_sysrand_if_available(uint8_t *buf, size_t len) {
57 CRYPTO_sysrand(buf, len);
58 return 1;
59 }
60
CRYPTO_sysrand_for_seed(uint8_t * out,size_t requested)61 void CRYPTO_sysrand_for_seed(uint8_t *out, size_t requested) {
62 CRYPTO_sysrand(out, requested);
63 }
64
65 #endif // OPENSSL_RAND_DETERMINISTIC
66