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#include <sys/types.h>
28#include <sys/socket.h>
29#ifdef HAVE_SYS_UN_H
30# include <sys/un.h>
31#endif
32
33#include <netinet/in.h>
34#include <arpa/inet.h>
35
36#include <errno.h>
37#include <signal.h>
38#include <string.h>
39#include <unistd.h>
40#include <stddef.h> /* for offsetof */
41
42#ifdef __APPLE_CRYPTO__
43#include "ossl-rand.h"
44#include "ossl-crypto.h"
45#include "ossl-err.h"
46#else
47#include <openssl/rand.h>
48#include <openssl/crypto.h>
49#include <openssl/err.h>
50#endif
51
52#include "ssh.h"
53#include "misc.h"
54#include "xmalloc.h"
55#include "atomicio.h"
56#include "pathnames.h"
57#include "log.h"
58#include "buffer.h"
59
60/*
61 * Portable OpenSSH PRNG seeding:
62 * If OpenSSL has not "internally seeded" itself (e.g. pulled data from
63 * /dev/random), then collect RANDOM_SEED_SIZE bytes of randomness from
64 * PRNGd.
65 */
66#ifndef OPENSSL_PRNG_ONLY
67
68#define RANDOM_SEED_SIZE 48
69
70/*
71 * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon
72 * listening either on 'tcp_port', or via Unix domain socket at *
73 * 'socket_path'.
74 * Either a non-zero tcp_port or a non-null socket_path must be
75 * supplied.
76 * Returns 0 on success, -1 on error
77 */
78int
79get_random_bytes_prngd(unsigned char *buf, int len,
80    unsigned short tcp_port, char *socket_path)
81{
82	int fd, addr_len, rval, errors;
83	u_char msg[2];
84	struct sockaddr_storage addr;
85	struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr;
86	struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr;
87	mysig_t old_sigpipe;
88
89	/* Sanity checks */
90	if (socket_path == NULL && tcp_port == 0)
91		fatal("You must specify a port or a socket");
92	if (socket_path != NULL &&
93	    strlen(socket_path) >= sizeof(addr_un->sun_path))
94		fatal("Random pool path is too long");
95	if (len <= 0 || len > 255)
96		fatal("Too many bytes (%d) to read from PRNGD", len);
97
98	memset(&addr, '\0', sizeof(addr));
99
100	if (tcp_port != 0) {
101		addr_in->sin_family = AF_INET;
102		addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
103		addr_in->sin_port = htons(tcp_port);
104		addr_len = sizeof(*addr_in);
105	} else {
106		addr_un->sun_family = AF_UNIX;
107		strlcpy(addr_un->sun_path, socket_path,
108		    sizeof(addr_un->sun_path));
109		addr_len = offsetof(struct sockaddr_un, sun_path) +
110		    strlen(socket_path) + 1;
111	}
112
113	old_sigpipe = mysignal(SIGPIPE, SIG_IGN);
114
115	errors = 0;
116	rval = -1;
117reopen:
118	fd = socket(addr.ss_family, SOCK_STREAM, 0);
119	if (fd == -1) {
120		error("Couldn't create socket: %s", strerror(errno));
121		goto done;
122	}
123
124	if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) {
125		if (tcp_port != 0) {
126			error("Couldn't connect to PRNGD port %d: %s",
127			    tcp_port, strerror(errno));
128		} else {
129			error("Couldn't connect to PRNGD socket \"%s\": %s",
130			    addr_un->sun_path, strerror(errno));
131		}
132		goto done;
133	}
134
135	/* Send blocking read request to PRNGD */
136	msg[0] = 0x02;
137	msg[1] = len;
138
139	if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) {
140		if (errno == EPIPE && errors < 10) {
141			close(fd);
142			errors++;
143			goto reopen;
144		}
145		error("Couldn't write to PRNGD socket: %s",
146		    strerror(errno));
147		goto done;
148	}
149
150	if (atomicio(read, fd, buf, len) != (size_t)len) {
151		if (errno == EPIPE && errors < 10) {
152			close(fd);
153			errors++;
154			goto reopen;
155		}
156		error("Couldn't read from PRNGD socket: %s",
157		    strerror(errno));
158		goto done;
159	}
160
161	rval = 0;
162done:
163	mysignal(SIGPIPE, old_sigpipe);
164	if (fd != -1)
165		close(fd);
166	return rval;
167}
168
169static int
170seed_from_prngd(unsigned char *buf, size_t bytes)
171{
172#ifdef PRNGD_PORT
173	debug("trying egd/prngd port %d", PRNGD_PORT);
174	if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0)
175		return 0;
176#endif
177#ifdef PRNGD_SOCKET
178	debug("trying egd/prngd socket %s", PRNGD_SOCKET);
179	if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0)
180		return 0;
181#endif
182	return -1;
183}
184
185void
186rexec_send_rng_seed(Buffer *m)
187{
188	u_char buf[RANDOM_SEED_SIZE];
189
190	if (RAND_bytes(buf, sizeof(buf)) <= 0) {
191		error("Couldn't obtain random bytes (error %ld)",
192		    ERR_get_error());
193		buffer_put_string(m, "", 0);
194	} else
195		buffer_put_string(m, buf, sizeof(buf));
196}
197
198void
199rexec_recv_rng_seed(Buffer *m)
200{
201	u_char *buf;
202	u_int len;
203
204	buf = buffer_get_string_ret(m, &len);
205	if (buf != NULL) {
206		debug3("rexec_recv_rng_seed: seeding rng with %u bytes", len);
207		RAND_add(buf, len, len);
208	}
209}
210#endif /* OPENSSL_PRNG_ONLY */
211
212void
213seed_rng(void)
214{
215#ifndef OPENSSL_PRNG_ONLY
216	unsigned char buf[RANDOM_SEED_SIZE];
217#endif
218	/*
219	 * OpenSSL version numbers: MNNFFPPS: major minor fix patch status
220	 * We match major, minor, fix and status (not patch) for <1.0.0.
221	 * After that, we acceptable compatible fix versions (so we
222	 * allow 1.0.1 to work with 1.0.0). Going backwards is only allowed
223	 * within a patch series.
224	 */
225	u_long version_mask = SSLeay() >= 0x1000000f ?  ~0xffff0L : ~0xff0L;
226	if (((SSLeay() ^ OPENSSL_VERSION_NUMBER) & version_mask) ||
227	    (SSLeay() >> 12) < (OPENSSL_VERSION_NUMBER >> 12))
228		fatal("OpenSSL version mismatch. Built against %lx, you "
229		    "have %lx", (u_long)OPENSSL_VERSION_NUMBER, SSLeay());
230
231#ifndef OPENSSL_PRNG_ONLY
232	if (RAND_status() == 1) {
233		debug3("RNG is ready, skipping seeding");
234		return;
235	}
236
237	if (seed_from_prngd(buf, sizeof(buf)) == -1)
238		fatal("Could not obtain seed from PRNGd");
239	RAND_add(buf, sizeof(buf), sizeof(buf));
240	memset(buf, '\0', sizeof(buf));
241
242#endif /* OPENSSL_PRNG_ONLY */
243	if (RAND_status() != 1)
244		fatal("PRNG is not seeded");
245}
246