1 /*
2 * Copyright (c) 2001 Damien Miller. All rights reserved.
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 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
24
25 #include "includes.h"
26
27 #define RANDOM_SEED_SIZE 48
28
29 #ifdef WITH_OPENSSL
30
31 #include <sys/types.h>
32
33 #include <errno.h>
34 #include <signal.h>
35 #include <stdlib.h>
36 #include <string.h>
37 #include <unistd.h>
38
39 #include <openssl/rand.h>
40 #include <openssl/crypto.h>
41 #include <openssl/err.h>
42
43 #include "openbsd-compat/openssl-compat.h"
44
45 #include "ssh.h"
46 #include "misc.h"
47 #include "xmalloc.h"
48 #include "atomicio.h"
49 #include "pathnames.h"
50 #include "log.h"
51 #include "sshbuf.h"
52 #include "ssherr.h"
53
54 /*
55 * Portable OpenSSH PRNG seeding:
56 * If OpenSSL has not "internally seeded" itself (e.g. pulled data from
57 * /dev/random), then collect RANDOM_SEED_SIZE bytes of randomness from
58 * PRNGd.
59 */
60
61 void
seed_rng(void)62 seed_rng(void)
63 {
64 unsigned char buf[RANDOM_SEED_SIZE];
65
66 /* Initialise libcrypto */
67 if (ssh_libcrypto_init() != 1)
68 fatal("libcrypto failed to initialize.");
69
70 if (!ssh_compatible_openssl(OPENSSL_VERSION_NUMBER,
71 OpenSSL_version_num()))
72 fatal("OpenSSL version mismatch. Built against %lx, you "
73 "have %lx", (u_long)OPENSSL_VERSION_NUMBER,
74 OpenSSL_version_num());
75
76 #ifndef OPENSSL_PRNG_ONLY
77 if (RAND_status() == 1)
78 debug3("RNG is ready, skipping seeding");
79 else {
80 if (seed_from_prngd(buf, sizeof(buf)) == -1)
81 fatal("Could not obtain seed from PRNGd");
82 RAND_add(buf, sizeof(buf), sizeof(buf));
83 }
84 #endif /* OPENSSL_PRNG_ONLY */
85
86 if (RAND_status() != 1)
87 fatal("PRNG is not seeded");
88
89 /* Ensure arc4random() is primed */
90 arc4random_buf(buf, sizeof(buf));
91 explicit_bzero(buf, sizeof(buf));
92 }
93
94 #else /* WITH_OPENSSL */
95
96 #include <stdlib.h>
97 #include <string.h>
98
99 /* Actual initialisation is handled in arc4random() */
100 void
seed_rng(void)101 seed_rng(void)
102 {
103 unsigned char buf[RANDOM_SEED_SIZE];
104
105 /* Ensure arc4random() is primed */
106 arc4random_buf(buf, sizeof(buf));
107 explicit_bzero(buf, sizeof(buf));
108 }
109
110 #endif /* WITH_OPENSSL */
111
112 void
reseed_prngs(void)113 reseed_prngs(void)
114 {
115 uint32_t rnd[256];
116
117 #ifdef WITH_OPENSSL
118 RAND_poll();
119 #endif
120 arc4random_stir(); /* noop on recent arc4random() implementations */
121 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */
122
123 #ifdef WITH_OPENSSL
124 RAND_seed(rnd, sizeof(rnd));
125 /* give libcrypto a chance to notice the PID change */
126 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
127 fatal_f("RAND_bytes failed");
128 #endif
129
130 explicit_bzero(rnd, sizeof(rnd));
131 }
132