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 #ifndef OPENSSL_PRNG_ONLY
61
62 void
rexec_send_rng_seed(struct sshbuf * m)63 rexec_send_rng_seed(struct sshbuf *m)
64 {
65 u_char buf[RANDOM_SEED_SIZE];
66 size_t len = sizeof(buf);
67 int r;
68
69 if (RAND_bytes(buf, sizeof(buf)) <= 0) {
70 error("Couldn't obtain random bytes (error %ld)",
71 ERR_get_error());
72 len = 0;
73 }
74 if ((r = sshbuf_put_string(m, buf, len)) != 0)
75 fatal("%s: buffer error: %s", __func__, ssh_err(r));
76 explicit_bzero(buf, sizeof(buf));
77 }
78
79 void
rexec_recv_rng_seed(struct sshbuf * m)80 rexec_recv_rng_seed(struct sshbuf *m)
81 {
82 const u_char *buf = NULL;
83 size_t len = 0;
84 int r;
85
86 if ((r = sshbuf_get_string_direct(m, &buf, &len)) != 0)
87 fatal("%s: buffer error: %s", __func__, ssh_err(r));
88
89 debug3("rexec_recv_rng_seed: seeding rng with %lu bytes",
90 (unsigned long)len);
91 RAND_add(buf, len, len);
92 }
93 #endif /* OPENSSL_PRNG_ONLY */
94
95 void
seed_rng(void)96 seed_rng(void)
97 {
98 unsigned char buf[RANDOM_SEED_SIZE];
99
100 /* Initialise libcrypto */
101 ssh_libcrypto_init();
102
103 if (!ssh_compatible_openssl(OPENSSL_VERSION_NUMBER,
104 OpenSSL_version_num()))
105 fatal("OpenSSL version mismatch. Built against %lx, you "
106 "have %lx", (u_long)OPENSSL_VERSION_NUMBER,
107 OpenSSL_version_num());
108
109 #ifndef OPENSSL_PRNG_ONLY
110 if (RAND_status() == 1)
111 debug3("RNG is ready, skipping seeding");
112 else {
113 if (seed_from_prngd(buf, sizeof(buf)) == -1)
114 fatal("Could not obtain seed from PRNGd");
115 RAND_add(buf, sizeof(buf), sizeof(buf));
116 }
117 #endif /* OPENSSL_PRNG_ONLY */
118
119 if (RAND_status() != 1)
120 fatal("PRNG is not seeded");
121
122 /* Ensure arc4random() is primed */
123 arc4random_buf(buf, sizeof(buf));
124 explicit_bzero(buf, sizeof(buf));
125 }
126
127 #else /* WITH_OPENSSL */
128
129 #include <stdlib.h>
130 #include <string.h>
131
132 /* Actual initialisation is handled in arc4random() */
133 void
seed_rng(void)134 seed_rng(void)
135 {
136 unsigned char buf[RANDOM_SEED_SIZE];
137
138 /* Ensure arc4random() is primed */
139 arc4random_buf(buf, sizeof(buf));
140 explicit_bzero(buf, sizeof(buf));
141 }
142
143 #endif /* WITH_OPENSSL */
144