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