Line data Source code
1 : /*
2 : * Copyright (c) 1997 - 2008 Kungliga Tekniska Högskolan
3 : * (Royal Institute of Technology, Stockholm, Sweden).
4 : * All rights reserved.
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 : *
10 : * 1. Redistributions of source code must retain the above copyright
11 : * notice, this list of conditions and the following disclaimer.
12 : *
13 : * 2. Redistributions in binary form must reproduce the above copyright
14 : * notice, this list of conditions and the following disclaimer in the
15 : * documentation and/or other materials provided with the distribution.
16 : *
17 : * 3. Neither the name of the Institute nor the names of its contributors
18 : * may be used to endorse or promote products derived from this software
19 : * without specific prior written permission.
20 : *
21 : * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22 : * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 : * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 : * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25 : * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 : * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 : * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 : * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 : * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 : * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 : * SUCH DAMAGE.
32 : */
33 :
34 : #include "krb5_locl.h"
35 :
36 : #define ENTROPY_NEEDED 128
37 :
38 : static HEIMDAL_MUTEX crypto_mutex = HEIMDAL_MUTEX_INITIALIZER;
39 :
40 : static int
41 18182 : seed_something(void)
42 : {
43 : char buf[1024], seedfile[256];
44 :
45 : /* If there is a seed file, load it. But such a file cannot be trusted,
46 : so use 0 for the entropy estimate */
47 18182 : if (RAND_file_name(seedfile, sizeof(seedfile))) {
48 : int fd;
49 18182 : fd = open(seedfile, O_RDONLY | O_BINARY | O_CLOEXEC);
50 18182 : if (fd >= 0) {
51 : ssize_t ret;
52 0 : rk_cloexec(fd);
53 0 : ret = read(fd, buf, sizeof(buf));
54 0 : if (ret > 0)
55 0 : RAND_add(buf, ret, 0.0);
56 0 : close(fd);
57 : } else
58 18182 : seedfile[0] = '\0';
59 : } else
60 0 : seedfile[0] = '\0';
61 :
62 : /* Calling RAND_status() will try to use /dev/urandom if it exists so
63 : we do not have to deal with it. */
64 18182 : if (RAND_status() != 1) {
65 : #ifndef _WIN32
66 : krb5_context context;
67 : const char *p;
68 :
69 : /* Try using egd */
70 0 : if (!krb5_init_context(&context)) {
71 0 : p = krb5_config_get_string(context, NULL, "libdefaults",
72 : "egd_socket", NULL);
73 0 : if (p != NULL)
74 0 : RAND_egd_bytes(p, ENTROPY_NEEDED);
75 0 : krb5_free_context(context);
76 : }
77 : #else
78 : /* TODO: Once a Windows CryptoAPI RAND method is defined, we
79 : can use that and failover to another method. */
80 : #endif
81 : }
82 :
83 18182 : if (RAND_status() == 1) {
84 : /* Update the seed file */
85 18182 : if (seedfile[0])
86 0 : RAND_write_file(seedfile);
87 :
88 17603 : return 0;
89 : } else
90 0 : return -1;
91 : }
92 :
93 : KRB5_LIB_FUNCTION void KRB5_LIB_CALL
94 1692745 : krb5_generate_random_block(void *buf, size_t len)
95 : {
96 : static int rng_initialized = 0;
97 :
98 : HEIMDAL_MUTEX_lock(&crypto_mutex);
99 1692745 : if (!rng_initialized) {
100 18182 : if (seed_something())
101 0 : krb5_abortx(NULL, "Fatal: could not seed the "
102 : "random number generator");
103 :
104 18182 : rng_initialized = 1;
105 : }
106 : HEIMDAL_MUTEX_unlock(&crypto_mutex);
107 1692745 : if (RAND_bytes(buf, len) <= 0)
108 0 : krb5_abortx(NULL, "Failed to generate random block");
109 1692745 : }
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