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Commit | Line | Data |
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8efc0c15 | 1 | /* |
5260325f | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5260325f | 5 | * Code to connect to a remote host, and to perform the client side of the |
6 | * login (authentication) dialog. | |
bcbf86ec | 7 | * |
8 | * As far as I am concerned, the code I have written for this software | |
9 | * can be used freely for any purpose. Any derived versions of this | |
10 | * software must be clearly marked as such, and if the derived work is | |
11 | * incompatible with the protocol description in the RFC file, it must be | |
12 | * called by a name other than "ssh" or "Secure Shell". | |
5260325f | 13 | */ |
8efc0c15 | 14 | |
15 | #include "includes.h" | |
8bbc048a | 16 | RCSID("$OpenBSD: sshconnect.c,v 1.111 2001/10/01 21:51:16 markus Exp $"); |
8efc0c15 | 17 | |
8ce64345 | 18 | #include <openssl/bn.h> |
a306f2dd | 19 | |
42f11eb2 | 20 | #include "ssh.h" |
8efc0c15 | 21 | #include "xmalloc.h" |
22 | #include "rsa.h" | |
8ce64345 | 23 | #include "buffer.h" |
8efc0c15 | 24 | #include "packet.h" |
8efc0c15 | 25 | #include "uidswap.h" |
26 | #include "compat.h" | |
4fe2af09 | 27 | #include "key.h" |
a306f2dd | 28 | #include "sshconnect.h" |
4fe2af09 | 29 | #include "hostfile.h" |
42f11eb2 | 30 | #include "log.h" |
31 | #include "readconf.h" | |
32 | #include "atomicio.h" | |
33 | #include "misc.h" | |
8efc0c15 | 34 | |
a306f2dd | 35 | char *client_version_string = NULL; |
36 | char *server_version_string = NULL; | |
8ce64345 | 37 | |
57112b5a | 38 | extern Options options; |
48e671d5 | 39 | extern char *__progname; |
57112b5a | 40 | |
42f11eb2 | 41 | /* AF_UNSPEC or AF_INET or AF_INET6 */ |
42 | extern int IPv4or6; | |
43 | ||
a704dd54 | 44 | #ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */ |
45 | #define INET6_ADDRSTRLEN 46 | |
46 | #endif | |
47 | ||
ce773142 | 48 | static const char * |
49 | sockaddr_ntop(struct sockaddr *sa) | |
50 | { | |
51 | void *addr; | |
52 | static char addrbuf[INET6_ADDRSTRLEN]; | |
53 | ||
54 | switch (sa->sa_family) { | |
55 | case AF_INET: | |
56 | addr = &((struct sockaddr_in *)sa)->sin_addr; | |
57 | break; | |
58 | case AF_INET6: | |
59 | addr = &((struct sockaddr_in6 *)sa)->sin6_addr; | |
60 | break; | |
61 | default: | |
62 | /* This case should be protected against elsewhere */ | |
63 | abort(); | |
64 | } | |
65 | inet_ntop(sa->sa_family, addr, addrbuf, sizeof(addrbuf)); | |
66 | return addrbuf; | |
67 | } | |
68 | ||
5260325f | 69 | /* |
70 | * Connect to the given ssh server using a proxy command. | |
71 | */ | |
396c147e | 72 | static int |
63bd8c36 | 73 | ssh_proxy_connect(const char *host, u_short port, struct passwd *pw, |
8efc0c15 | 74 | const char *proxy_command) |
75 | { | |
5260325f | 76 | Buffer command; |
77 | const char *cp; | |
78 | char *command_string; | |
79 | int pin[2], pout[2]; | |
9da5c3c9 | 80 | pid_t pid; |
48e671d5 | 81 | char strport[NI_MAXSERV]; |
5260325f | 82 | |
83 | /* Convert the port number into a string. */ | |
48e671d5 | 84 | snprintf(strport, sizeof strport, "%hu", port); |
5260325f | 85 | |
86 | /* Build the final command string in the buffer by making the | |
87 | appropriate substitutions to the given proxy command. */ | |
88 | buffer_init(&command); | |
89 | for (cp = proxy_command; *cp; cp++) { | |
90 | if (cp[0] == '%' && cp[1] == '%') { | |
91 | buffer_append(&command, "%", 1); | |
92 | cp++; | |
93 | continue; | |
94 | } | |
95 | if (cp[0] == '%' && cp[1] == 'h') { | |
96 | buffer_append(&command, host, strlen(host)); | |
97 | cp++; | |
98 | continue; | |
99 | } | |
100 | if (cp[0] == '%' && cp[1] == 'p') { | |
48e671d5 | 101 | buffer_append(&command, strport, strlen(strport)); |
5260325f | 102 | cp++; |
103 | continue; | |
104 | } | |
105 | buffer_append(&command, cp, 1); | |
8efc0c15 | 106 | } |
5260325f | 107 | buffer_append(&command, "\0", 1); |
108 | ||
109 | /* Get the final command string. */ | |
110 | command_string = buffer_ptr(&command); | |
111 | ||
112 | /* Create pipes for communicating with the proxy. */ | |
113 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
114 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
115 | strerror(errno)); | |
116 | ||
117 | debug("Executing proxy command: %.500s", command_string); | |
118 | ||
119 | /* Fork and execute the proxy command. */ | |
120 | if ((pid = fork()) == 0) { | |
121 | char *argv[10]; | |
122 | ||
123 | /* Child. Permanently give up superuser privileges. */ | |
63bd8c36 | 124 | permanently_set_uid(pw); |
5260325f | 125 | |
126 | /* Redirect stdin and stdout. */ | |
127 | close(pin[1]); | |
128 | if (pin[0] != 0) { | |
129 | if (dup2(pin[0], 0) < 0) | |
130 | perror("dup2 stdin"); | |
131 | close(pin[0]); | |
132 | } | |
133 | close(pout[0]); | |
134 | if (dup2(pout[1], 1) < 0) | |
135 | perror("dup2 stdout"); | |
136 | /* Cannot be 1 because pin allocated two descriptors. */ | |
137 | close(pout[1]); | |
138 | ||
139 | /* Stderr is left as it is so that error messages get | |
140 | printed on the user's terminal. */ | |
30228d7c | 141 | argv[0] = _PATH_BSHELL; |
5260325f | 142 | argv[1] = "-c"; |
143 | argv[2] = command_string; | |
144 | argv[3] = NULL; | |
145 | ||
146 | /* Execute the proxy command. Note that we gave up any | |
147 | extra privileges above. */ | |
328654d8 | 148 | execv(argv[0], argv); |
149 | perror(argv[0]); | |
5260325f | 150 | exit(1); |
8efc0c15 | 151 | } |
5260325f | 152 | /* Parent. */ |
153 | if (pid < 0) | |
154 | fatal("fork failed: %.100s", strerror(errno)); | |
155 | ||
156 | /* Close child side of the descriptors. */ | |
157 | close(pin[0]); | |
158 | close(pout[1]); | |
159 | ||
160 | /* Free the command name. */ | |
161 | buffer_free(&command); | |
162 | ||
163 | /* Set the connection file descriptors. */ | |
164 | packet_set_connection(pout[0], pin[1]); | |
8efc0c15 | 165 | |
ce773142 | 166 | /* Indicate OK return */ |
167 | return 0; | |
5260325f | 168 | } |
8efc0c15 | 169 | |
5260325f | 170 | /* |
171 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
172 | */ | |
396c147e | 173 | static int |
63bd8c36 | 174 | ssh_create_socket(struct passwd *pw, int privileged, int family) |
8efc0c15 | 175 | { |
3435f5a6 | 176 | int sock, gaierr; |
177 | struct addrinfo hints, *res; | |
5260325f | 178 | |
aa3378df | 179 | /* |
180 | * If we are running as root and want to connect to a privileged | |
181 | * port, bind our own socket to a privileged port. | |
182 | */ | |
5260325f | 183 | if (privileged) { |
184 | int p = IPPORT_RESERVED - 1; | |
48e671d5 | 185 | sock = rresvport_af(&p, family); |
5260325f | 186 | if (sock < 0) |
c8d54615 | 187 | error("rresvport: af=%d %.100s", family, strerror(errno)); |
188 | else | |
189 | debug("Allocated local port %d.", p); | |
3435f5a6 | 190 | return sock; |
191 | } | |
192 | /* | |
193 | * Just create an ordinary socket on arbitrary port. We use | |
194 | * the user's uid to create the socket. | |
195 | */ | |
196 | temporarily_use_uid(pw); | |
197 | sock = socket(family, SOCK_STREAM, 0); | |
198 | if (sock < 0) | |
199 | error("socket: %.100s", strerror(errno)); | |
200 | restore_uid(); | |
201 | ||
202 | /* Bind the socket to an alternative local IP address */ | |
203 | if (options.bind_address == NULL) | |
204 | return sock; | |
205 | ||
206 | memset(&hints, 0, sizeof(hints)); | |
207 | hints.ai_family = IPv4or6; | |
208 | hints.ai_socktype = SOCK_STREAM; | |
209 | hints.ai_flags = AI_PASSIVE; | |
210 | gaierr = getaddrinfo(options.bind_address, "0", &hints, &res); | |
211 | if (gaierr) { | |
212 | error("getaddrinfo: %s: %s", options.bind_address, | |
213 | gai_strerror(gaierr)); | |
214 | close(sock); | |
215 | return -1; | |
216 | } | |
217 | if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { | |
218 | error("bind: %s: %s", options.bind_address, strerror(errno)); | |
219 | close(sock); | |
220 | freeaddrinfo(res); | |
221 | return -1; | |
5260325f | 222 | } |
3435f5a6 | 223 | freeaddrinfo(res); |
5260325f | 224 | return sock; |
8efc0c15 | 225 | } |
226 | ||
5260325f | 227 | /* |
48e671d5 | 228 | * Opens a TCP/IP connection to the remote server on the given host. |
229 | * The address of the remote host will be returned in hostaddr. | |
230 | * If port is 0, the default port will be used. If anonymous is zero, | |
5260325f | 231 | * a privileged port will be allocated to make the connection. |
232 | * This requires super-user privileges if anonymous is false. | |
233 | * Connection_attempts specifies the maximum number of tries (one per | |
234 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
235 | * and %p substituted for host and port, respectively) to use to contact | |
236 | * the daemon. | |
ce773142 | 237 | * Return values: |
238 | * 0 for OK | |
239 | * ECONNREFUSED if we got a "Connection Refused" by the peer on any address | |
240 | * ECONNABORTED if we failed without a "Connection refused" | |
241 | * Suitable error messages for the connection failure will already have been | |
242 | * printed. | |
5260325f | 243 | */ |
244 | int | |
48e671d5 | 245 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, |
57112b5a | 246 | u_short port, int connection_attempts, |
63bd8c36 | 247 | int anonymous, struct passwd *pw, |
5260325f | 248 | const char *proxy_command) |
8efc0c15 | 249 | { |
b5c334cc | 250 | int gaierr; |
251 | int on = 1; | |
48e671d5 | 252 | int sock = -1, attempt; |
48e671d5 | 253 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; |
b5c334cc | 254 | struct addrinfo hints, *ai, *aitop; |
5260325f | 255 | struct linger linger; |
b5c334cc | 256 | struct servent *sp; |
ce773142 | 257 | /* |
258 | * Did we get only other errors than "Connection refused" (which | |
259 | * should block fallback to rsh and similar), or did we get at least | |
260 | * one "Connection refused"? | |
261 | */ | |
262 | int full_failure = 1; | |
5260325f | 263 | |
14a9a859 | 264 | debug("ssh_connect: getuid %u geteuid %u anon %d", |
265 | (u_int) getuid(), (u_int) geteuid(), anonymous); | |
5260325f | 266 | |
267 | /* Get default port if port has not been set. */ | |
268 | if (port == 0) { | |
269 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
270 | if (sp) | |
271 | port = ntohs(sp->s_port); | |
272 | else | |
273 | port = SSH_DEFAULT_PORT; | |
8efc0c15 | 274 | } |
5260325f | 275 | /* If a proxy command is given, connect using it. */ |
276 | if (proxy_command != NULL) | |
63bd8c36 | 277 | return ssh_proxy_connect(host, port, pw, proxy_command); |
5260325f | 278 | |
279 | /* No proxy command. */ | |
280 | ||
48e671d5 | 281 | memset(&hints, 0, sizeof(hints)); |
282 | hints.ai_family = IPv4or6; | |
283 | hints.ai_socktype = SOCK_STREAM; | |
284 | snprintf(strport, sizeof strport, "%d", port); | |
285 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) | |
286 | fatal("%s: %.100s: %s", __progname, host, | |
287 | gai_strerror(gaierr)); | |
5260325f | 288 | |
95f1eccc | 289 | /* |
290 | * Try to connect several times. On some machines, the first time | |
291 | * will sometimes fail. In general socket code appears to behave | |
292 | * quite magically on many machines. | |
ce773142 | 293 | */ |
294 | for (attempt = 0; ;) { | |
5260325f | 295 | if (attempt > 0) |
296 | debug("Trying again..."); | |
297 | ||
48e671d5 | 298 | /* Loop through addresses for this host, and try each one in |
6ae2364d | 299 | sequence until the connection succeeds. */ |
48e671d5 | 300 | for (ai = aitop; ai; ai = ai->ai_next) { |
301 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
302 | continue; | |
303 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
304 | ntop, sizeof(ntop), strport, sizeof(strport), | |
305 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
306 | error("ssh_connect: getnameinfo failed"); | |
307 | continue; | |
308 | } | |
309 | debug("Connecting to %.200s [%.100s] port %s.", | |
310 | host, ntop, strport); | |
311 | ||
312 | /* Create a socket for connecting. */ | |
63bd8c36 | 313 | sock = ssh_create_socket(pw, |
3c62e7eb | 314 | #ifdef HAVE_CYGWIN |
fa08c86b | 315 | !anonymous, |
3c62e7eb | 316 | #else |
fa08c86b | 317 | !anonymous && geteuid() == 0, |
3c62e7eb | 318 | #endif |
48e671d5 | 319 | ai->ai_family); |
320 | if (sock < 0) | |
ce773142 | 321 | /* Any error is already output */ |
48e671d5 | 322 | continue; |
323 | ||
324 | /* Connect to the host. We use the user's uid in the | |
325 | * hope that it will help with tcp_wrappers showing | |
326 | * the remote uid as root. | |
aa3378df | 327 | */ |
63bd8c36 | 328 | temporarily_use_uid(pw); |
48e671d5 | 329 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { |
330 | /* Successful connection. */ | |
cd332296 | 331 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); |
5260325f | 332 | restore_uid(); |
333 | break; | |
48e671d5 | 334 | } else { |
ce773142 | 335 | if (errno == ECONNREFUSED) |
336 | full_failure = 0; | |
337 | log("ssh: connect to address %s port %s: %s", | |
338 | sockaddr_ntop(ai->ai_addr), strport, | |
339 | strerror(errno)); | |
5260325f | 340 | restore_uid(); |
aa3378df | 341 | /* |
342 | * Close the failed socket; there appear to | |
343 | * be some problems when reusing a socket for | |
344 | * which connect() has already returned an | |
345 | * error. | |
346 | */ | |
5260325f | 347 | shutdown(sock, SHUT_RDWR); |
348 | close(sock); | |
349 | } | |
8efc0c15 | 350 | } |
48e671d5 | 351 | if (ai) |
352 | break; /* Successful connection. */ | |
8efc0c15 | 353 | |
ce773142 | 354 | attempt++; |
355 | if (attempt >= connection_attempts) | |
356 | break; | |
5260325f | 357 | /* Sleep a moment before retrying. */ |
358 | sleep(1); | |
359 | } | |
48e671d5 | 360 | |
361 | freeaddrinfo(aitop); | |
362 | ||
5260325f | 363 | /* Return failure if we didn't get a successful connection. */ |
364 | if (attempt >= connection_attempts) | |
ce773142 | 365 | return full_failure ? ECONNABORTED : ECONNREFUSED; |
8efc0c15 | 366 | |
5260325f | 367 | debug("Connection established."); |
8efc0c15 | 368 | |
aa3378df | 369 | /* |
370 | * Set socket options. We would like the socket to disappear as soon | |
371 | * as it has been closed for whatever reason. | |
372 | */ | |
373 | /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 374 | linger.l_onoff = 1; |
375 | linger.l_linger = 5; | |
b5c334cc | 376 | setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger)); |
377 | ||
378 | /* Set keepalives if requested. */ | |
379 | if (options.keepalives && | |
380 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, | |
381 | sizeof(on)) < 0) | |
382 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
8efc0c15 | 383 | |
5260325f | 384 | /* Set the connection. */ |
385 | packet_set_connection(sock, sock); | |
8efc0c15 | 386 | |
ce773142 | 387 | return 0; |
8efc0c15 | 388 | } |
389 | ||
5260325f | 390 | /* |
391 | * Waits for the server identification string, and sends our own | |
392 | * identification string. | |
393 | */ | |
396c147e | 394 | static void |
5ca51e19 | 395 | ssh_exchange_identification(void) |
8efc0c15 | 396 | { |
5260325f | 397 | char buf[256], remote_version[256]; /* must be same size! */ |
a8be9f80 | 398 | int remote_major, remote_minor, i, mismatch; |
5260325f | 399 | int connection_in = packet_get_connection_in(); |
400 | int connection_out = packet_get_connection_out(); | |
2b87da3b | 401 | int minor1 = PROTOCOL_MINOR_1; |
5260325f | 402 | |
403 | /* Read other side\'s version identification. */ | |
38c295d6 | 404 | for (;;) { |
405 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
406 | int len = atomicio(read, connection_in, &buf[i], 1); | |
407 | if (len < 0) | |
408 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); | |
409 | if (len != 1) | |
410 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
411 | if (buf[i] == '\r') { | |
412 | buf[i] = '\n'; | |
413 | buf[i + 1] = 0; | |
414 | continue; /**XXX wait for \n */ | |
415 | } | |
416 | if (buf[i] == '\n') { | |
417 | buf[i + 1] = 0; | |
418 | break; | |
419 | } | |
5260325f | 420 | } |
38c295d6 | 421 | buf[sizeof(buf) - 1] = 0; |
422 | if (strncmp(buf, "SSH-", 4) == 0) | |
5260325f | 423 | break; |
38c295d6 | 424 | debug("ssh_exchange_identification: %s", buf); |
8efc0c15 | 425 | } |
8ce64345 | 426 | server_version_string = xstrdup(buf); |
5260325f | 427 | |
aa3378df | 428 | /* |
429 | * Check that the versions match. In future this might accept | |
430 | * several versions and set appropriate flags to handle them. | |
431 | */ | |
8ce64345 | 432 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", |
433 | &remote_major, &remote_minor, remote_version) != 3) | |
5260325f | 434 | fatal("Bad remote protocol version identification: '%.100s'", buf); |
435 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
436 | remote_major, remote_minor, remote_version); | |
437 | ||
8ce64345 | 438 | compat_datafellows(remote_version); |
a8be9f80 | 439 | mismatch = 0; |
440 | ||
441 | switch(remote_major) { | |
442 | case 1: | |
443 | if (remote_minor == 99 && | |
444 | (options.protocol & SSH_PROTO_2) && | |
445 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
446 | enable_compat20(); | |
447 | break; | |
5260325f | 448 | } |
a8be9f80 | 449 | if (!(options.protocol & SSH_PROTO_1)) { |
450 | mismatch = 1; | |
451 | break; | |
452 | } | |
453 | if (remote_minor < 3) { | |
454 | fatal("Remote machine has too old SSH software version."); | |
fa08c86b | 455 | } else if (remote_minor == 3 || remote_minor == 4) { |
a8be9f80 | 456 | /* We speak 1.3, too. */ |
457 | enable_compat13(); | |
fa08c86b | 458 | minor1 = 3; |
a8be9f80 | 459 | if (options.forward_agent) { |
460 | log("Agent forwarding disabled for protocol 1.3"); | |
461 | options.forward_agent = 0; | |
462 | } | |
463 | } | |
464 | break; | |
465 | case 2: | |
466 | if (options.protocol & SSH_PROTO_2) { | |
467 | enable_compat20(); | |
468 | break; | |
469 | } | |
470 | /* FALLTHROUGH */ | |
6ae2364d | 471 | default: |
a8be9f80 | 472 | mismatch = 1; |
473 | break; | |
8efc0c15 | 474 | } |
a8be9f80 | 475 | if (mismatch) |
5260325f | 476 | fatal("Protocol major versions differ: %d vs. %d", |
a8be9f80 | 477 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
478 | remote_major); | |
5260325f | 479 | /* Send our own protocol version identification. */ |
480 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
a8be9f80 | 481 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
fa08c86b | 482 | compat20 ? PROTOCOL_MINOR_2 : minor1, |
8ce64345 | 483 | SSH_VERSION); |
a408af76 | 484 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) |
5260325f | 485 | fatal("write: %.100s", strerror(errno)); |
8ce64345 | 486 | client_version_string = xstrdup(buf); |
487 | chop(client_version_string); | |
488 | chop(server_version_string); | |
489 | debug("Local version string %.100s", client_version_string); | |
8efc0c15 | 490 | } |
491 | ||
f21032a6 | 492 | /* defaults to 'no' */ |
396c147e | 493 | static int |
5260325f | 494 | read_yes_or_no(const char *prompt, int defval) |
8efc0c15 | 495 | { |
5260325f | 496 | char buf[1024]; |
497 | FILE *f; | |
498 | int retval = -1; | |
499 | ||
f21032a6 | 500 | if (options.batch_mode) |
501 | return 0; | |
502 | ||
7c49df64 | 503 | if (isatty(STDIN_FILENO)) |
5260325f | 504 | f = stdin; |
505 | else | |
5ca51e19 | 506 | f = fopen(_PATH_TTY, "rw"); |
5260325f | 507 | |
508 | if (f == NULL) | |
509 | return 0; | |
510 | ||
511 | fflush(stdout); | |
512 | ||
513 | while (1) { | |
514 | fprintf(stderr, "%s", prompt); | |
515 | if (fgets(buf, sizeof(buf), f) == NULL) { | |
f49bc4f7 | 516 | /* |
517 | * Print a newline (the prompt probably didn\'t have | |
518 | * one). | |
519 | */ | |
5260325f | 520 | fprintf(stderr, "\n"); |
521 | strlcpy(buf, "no", sizeof buf); | |
522 | } | |
523 | /* Remove newline from response. */ | |
524 | if (strchr(buf, '\n')) | |
525 | *strchr(buf, '\n') = 0; | |
526 | ||
527 | if (buf[0] == 0) | |
528 | retval = defval; | |
529 | if (strcmp(buf, "yes") == 0) | |
530 | retval = 1; | |
188adeb2 | 531 | else if (strcmp(buf, "no") == 0) |
5260325f | 532 | retval = 0; |
188adeb2 | 533 | else |
534 | fprintf(stderr, "Please type 'yes' or 'no'.\n"); | |
5260325f | 535 | |
536 | if (retval != -1) { | |
537 | if (f != stdin) | |
538 | fclose(f); | |
539 | return retval; | |
540 | } | |
8efc0c15 | 541 | } |
8efc0c15 | 542 | } |
543 | ||
5260325f | 544 | /* |
f49bc4f7 | 545 | * check whether the supplied host key is valid, return -1 if the key |
546 | * is not valid. the user_hostfile will not be updated if 'readonly' is true. | |
5260325f | 547 | */ |
95f1eccc | 548 | |
396c147e | 549 | static int |
a306f2dd | 550 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, |
f49bc4f7 | 551 | int readonly, const char *user_hostfile, const char *system_hostfile) |
8efc0c15 | 552 | { |
4fe2af09 | 553 | Key *file_key; |
1d1ffb87 | 554 | char *type = key_type(host_key); |
95f1eccc | 555 | char *ip = NULL; |
22138a36 | 556 | char hostline[1000], *hostp, *fp; |
5260325f | 557 | HostStatus host_status; |
558 | HostStatus ip_status; | |
48e671d5 | 559 | int local = 0, host_ip_differ = 0; |
20af321f | 560 | int salen; |
48e671d5 | 561 | char ntop[NI_MAXHOST]; |
7c49df64 | 562 | int host_line, ip_line; |
1e3b8b07 | 563 | const char *host_file = NULL, *ip_file = NULL; |
48e671d5 | 564 | |
565 | /* | |
566 | * Force accepting of the host key for loopback/localhost. The | |
567 | * problem is that if the home directory is NFS-mounted to multiple | |
568 | * machines, localhost will refer to a different machine in each of | |
569 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
570 | * essentially disables host authentication for localhost; however, | |
571 | * this is probably not a real problem. | |
572 | */ | |
a306f2dd | 573 | /** hostaddr == 0! */ |
48e671d5 | 574 | switch (hostaddr->sa_family) { |
575 | case AF_INET: | |
f49bc4f7 | 576 | local = (ntohl(((struct sockaddr_in *)hostaddr)-> |
577 | sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; | |
20af321f | 578 | salen = sizeof(struct sockaddr_in); |
48e671d5 | 579 | break; |
580 | case AF_INET6: | |
f49bc4f7 | 581 | local = IN6_IS_ADDR_LOOPBACK( |
582 | &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
20af321f | 583 | salen = sizeof(struct sockaddr_in6); |
48e671d5 | 584 | break; |
585 | default: | |
586 | local = 0; | |
20af321f | 587 | salen = sizeof(struct sockaddr_storage); |
48e671d5 | 588 | break; |
589 | } | |
8bbc048a | 590 | if (options.no_host_authentication_for_localhost == 1 && local && |
591 | options.host_key_alias == NULL) { | |
7c49df64 | 592 | debug("Forcing accepting of host key for " |
593 | "loopback/localhost."); | |
f49bc4f7 | 594 | return 0; |
48e671d5 | 595 | } |
5260325f | 596 | |
57112b5a | 597 | /* |
7c49df64 | 598 | * We don't have the remote ip-address for connections |
599 | * using a proxy command | |
600 | */ | |
601 | if (options.proxy_command == NULL) { | |
602 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), | |
603 | NULL, 0, NI_NUMERICHOST) != 0) | |
604 | fatal("check_host_key: getnameinfo failed"); | |
605 | ip = xstrdup(ntop); | |
606 | } else { | |
607 | ip = xstrdup("<no hostip for proxy command>"); | |
608 | } | |
609 | /* | |
610 | * Turn off check_host_ip if the connection is to localhost, via proxy | |
611 | * command or if we don't have a hostname to compare with | |
57112b5a | 612 | */ |
7c49df64 | 613 | if (options.check_host_ip && |
614 | (local || strcmp(host, ip) == 0 || options.proxy_command != NULL)) | |
57112b5a | 615 | options.check_host_ip = 0; |
616 | ||
8abcdba4 | 617 | /* |
7c49df64 | 618 | * Allow the user to record the key under a different name. This is |
8abcdba4 | 619 | * useful for ssh tunneling over forwarded connections or if you run |
7c49df64 | 620 | * multiple sshd's on different ports on the same machine. |
8abcdba4 | 621 | */ |
622 | if (options.host_key_alias != NULL) { | |
623 | host = options.host_key_alias; | |
624 | debug("using hostkeyalias: %s", host); | |
625 | } | |
626 | ||
95f1eccc | 627 | /* |
628 | * Store the host key from the known host file in here so that we can | |
629 | * compare it with the key for the IP address. | |
630 | */ | |
4fe2af09 | 631 | file_key = key_new(host_key->type); |
5260325f | 632 | |
aa3378df | 633 | /* |
634 | * Check if the host key is present in the user\'s list of known | |
635 | * hosts or in the systemwide list. | |
636 | */ | |
1e3b8b07 | 637 | host_file = user_hostfile; |
f49bc4f7 | 638 | host_status = check_host_in_hostfile(host_file, host, host_key, |
639 | file_key, &host_line); | |
1e3b8b07 | 640 | if (host_status == HOST_NEW) { |
641 | host_file = system_hostfile; | |
f49bc4f7 | 642 | host_status = check_host_in_hostfile(host_file, host, host_key, |
643 | file_key, &host_line); | |
1e3b8b07 | 644 | } |
aa3378df | 645 | /* |
646 | * Also perform check for the ip address, skip the check if we are | |
647 | * localhost or the hostname was an ip address to begin with | |
648 | */ | |
7c49df64 | 649 | if (options.check_host_ip) { |
4fe2af09 | 650 | Key *ip_key = key_new(host_key->type); |
5260325f | 651 | |
1e3b8b07 | 652 | ip_file = user_hostfile; |
f49bc4f7 | 653 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, |
654 | ip_key, &ip_line); | |
1e3b8b07 | 655 | if (ip_status == HOST_NEW) { |
656 | ip_file = system_hostfile; | |
f49bc4f7 | 657 | ip_status = check_host_in_hostfile(ip_file, ip, |
658 | host_key, ip_key, &ip_line); | |
1e3b8b07 | 659 | } |
5260325f | 660 | if (host_status == HOST_CHANGED && |
4fe2af09 | 661 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) |
5260325f | 662 | host_ip_differ = 1; |
663 | ||
4fe2af09 | 664 | key_free(ip_key); |
5260325f | 665 | } else |
666 | ip_status = host_status; | |
667 | ||
4fe2af09 | 668 | key_free(file_key); |
5260325f | 669 | |
670 | switch (host_status) { | |
671 | case HOST_OK: | |
672 | /* The host is known and the key matches. */ | |
1d1ffb87 | 673 | debug("Host '%.200s' is known and matches the %s host key.", |
674 | host, type); | |
1e3b8b07 | 675 | debug("Found key in %s:%d", host_file, host_line); |
7c49df64 | 676 | if (options.check_host_ip && ip_status == HOST_NEW) { |
f49bc4f7 | 677 | if (readonly) |
678 | log("%s host key for IP address " | |
679 | "'%.128s' not in list of known hosts.", | |
7c49df64 | 680 | type, ip); |
f49bc4f7 | 681 | else if (!add_host_to_hostfile(user_hostfile, ip, |
682 | host_key)) | |
683 | log("Failed to add the %s host key for IP " | |
684 | "address '%.128s' to the list of known " | |
685 | "hosts (%.30s).", type, ip, user_hostfile); | |
686 | else | |
687 | log("Warning: Permanently added the %s host " | |
688 | "key for IP address '%.128s' to the list " | |
689 | "of known hosts.", type, ip); | |
5260325f | 690 | } |
691 | break; | |
692 | case HOST_NEW: | |
f49bc4f7 | 693 | if (readonly) |
694 | goto fail; | |
5260325f | 695 | /* The host is new. */ |
696 | if (options.strict_host_key_checking == 1) { | |
f49bc4f7 | 697 | /* |
698 | * User has requested strict host key checking. We | |
699 | * will not add the host key automatically. The only | |
700 | * alternative left is to abort. | |
701 | */ | |
702 | error("No %s host key is known for %.200s and you " | |
703 | "have requested strict checking.", type, host); | |
704 | goto fail; | |
5260325f | 705 | } else if (options.strict_host_key_checking == 2) { |
706 | /* The default */ | |
707 | char prompt[1024]; | |
22138a36 | 708 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
5260325f | 709 | snprintf(prompt, sizeof(prompt), |
f49bc4f7 | 710 | "The authenticity of host '%.200s (%s)' can't be " |
711 | "established.\n" | |
1d1ffb87 | 712 | "%s key fingerprint is %s.\n" |
f49bc4f7 | 713 | "Are you sure you want to continue connecting " |
714 | "(yes/no)? ", host, ip, type, fp); | |
22138a36 | 715 | xfree(fp); |
f49bc4f7 | 716 | if (!read_yes_or_no(prompt, -1)) { |
717 | log("Aborted by user!"); | |
718 | goto fail; | |
719 | } | |
5260325f | 720 | } |
7c49df64 | 721 | if (options.check_host_ip && ip_status == HOST_NEW) { |
5260325f | 722 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); |
723 | hostp = hostline; | |
724 | } else | |
725 | hostp = host; | |
726 | ||
f49bc4f7 | 727 | /* |
728 | * If not in strict mode, add the key automatically to the | |
729 | * local known_hosts file. | |
730 | */ | |
a306f2dd | 731 | if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) |
f49bc4f7 | 732 | log("Failed to add the host to the list of known " |
733 | "hosts (%.500s).", user_hostfile); | |
5260325f | 734 | else |
f49bc4f7 | 735 | log("Warning: Permanently added '%.200s' (%s) to the " |
736 | "list of known hosts.", hostp, type); | |
5260325f | 737 | break; |
738 | case HOST_CHANGED: | |
739 | if (options.check_host_ip && host_ip_differ) { | |
740 | char *msg; | |
741 | if (ip_status == HOST_NEW) | |
742 | msg = "is unknown"; | |
743 | else if (ip_status == HOST_OK) | |
744 | msg = "is unchanged"; | |
745 | else | |
746 | msg = "has a different value"; | |
747 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
748 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
749 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1d1ffb87 | 750 | error("The %s host key for %s has changed,", type, host); |
5260325f | 751 | error("and the key for the according IP address %s", ip); |
752 | error("%s. This could either mean that", msg); | |
753 | error("DNS SPOOFING is happening or the IP address for the host"); | |
1e3b8b07 | 754 | error("and its host key have changed at the same time."); |
7c49df64 | 755 | if (ip_status != HOST_NEW) |
1e3b8b07 | 756 | error("Offending key for IP in %s:%d", ip_file, ip_line); |
5260325f | 757 | } |
758 | /* The host key has changed. */ | |
22138a36 | 759 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
5260325f | 760 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
ae2f7af7 | 761 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); |
5260325f | 762 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
763 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
764 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
1d1ffb87 | 765 | error("It is also possible that the %s host key has just been changed.", type); |
8abcdba4 | 766 | error("The fingerprint for the %s key sent by the remote host is\n%s.", |
22138a36 | 767 | type, fp); |
5260325f | 768 | error("Please contact your system administrator."); |
769 | error("Add correct host key in %.100s to get rid of this message.", | |
8abcdba4 | 770 | user_hostfile); |
1e3b8b07 | 771 | error("Offending key in %s:%d", host_file, host_line); |
22138a36 | 772 | xfree(fp); |
5260325f | 773 | |
aa3378df | 774 | /* |
775 | * If strict host key checking is in use, the user will have | |
776 | * to edit the key manually and we can only abort. | |
777 | */ | |
f49bc4f7 | 778 | if (options.strict_host_key_checking) { |
779 | error("%s host key for %.200s has changed and you have " | |
780 | "requested strict checking.", type, host); | |
781 | goto fail; | |
782 | } | |
5260325f | 783 | |
aa3378df | 784 | /* |
785 | * If strict host key checking has not been requested, allow | |
786 | * the connection but without password authentication or | |
787 | * agent forwarding. | |
788 | */ | |
5260325f | 789 | if (options.password_authentication) { |
f49bc4f7 | 790 | error("Password authentication is disabled to avoid " |
791 | "man-in-the-middle attacks."); | |
5260325f | 792 | options.password_authentication = 0; |
793 | } | |
794 | if (options.forward_agent) { | |
f49bc4f7 | 795 | error("Agent forwarding is disabled to avoid " |
796 | "man-in-the-middle attacks."); | |
5260325f | 797 | options.forward_agent = 0; |
798 | } | |
0b6fbf03 | 799 | if (options.forward_x11) { |
f49bc4f7 | 800 | error("X11 forwarding is disabled to avoid " |
801 | "man-in-the-middle attacks."); | |
0b6fbf03 | 802 | options.forward_x11 = 0; |
803 | } | |
f49bc4f7 | 804 | if (options.num_local_forwards > 0 || |
805 | options.num_remote_forwards > 0) { | |
806 | error("Port forwarding is disabled to avoid " | |
807 | "man-in-the-middle attacks."); | |
808 | options.num_local_forwards = | |
809 | options.num_remote_forwards = 0; | |
0b6fbf03 | 810 | } |
aa3378df | 811 | /* |
812 | * XXX Should permit the user to change to use the new id. | |
813 | * This could be done by converting the host key to an | |
814 | * identifying sentence, tell that the host identifies itself | |
815 | * by that sentence, and ask the user if he/she whishes to | |
816 | * accept the authentication. | |
817 | */ | |
5260325f | 818 | break; |
819 | } | |
0b6fbf03 | 820 | |
7c49df64 | 821 | if (options.check_host_ip && host_status != HOST_CHANGED && |
822 | ip_status == HOST_CHANGED) { | |
823 | log("Warning: the %s host key for '%.200s' " | |
5d1d11d1 | 824 | "differs from the key for the IP address '%.128s'", |
7c49df64 | 825 | type, host, ip); |
826 | if (host_status == HOST_OK) | |
827 | log("Matching host key in %s:%d", host_file, host_line); | |
828 | log("Offending key for IP in %s:%d", ip_file, ip_line); | |
829 | if (options.strict_host_key_checking == 1) { | |
f49bc4f7 | 830 | error("Exiting, you have requested strict checking."); |
831 | goto fail; | |
7c49df64 | 832 | } else if (options.strict_host_key_checking == 2) { |
f49bc4f7 | 833 | if (!read_yes_or_no("Are you sure you want " |
834 | "to continue connecting (yes/no)? ", -1)) { | |
835 | log("Aborted by user!"); | |
836 | goto fail; | |
837 | } | |
7c49df64 | 838 | } |
839 | } | |
840 | ||
0b6fbf03 | 841 | xfree(ip); |
f49bc4f7 | 842 | return 0; |
843 | ||
844 | fail: | |
845 | xfree(ip); | |
846 | return -1; | |
847 | } | |
848 | ||
849 | int | |
850 | verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) | |
851 | { | |
852 | struct stat st; | |
853 | ||
854 | /* return ok if the key can be found in an old keyfile */ | |
855 | if (stat(options.system_hostfile2, &st) == 0 || | |
856 | stat(options.user_hostfile2, &st) == 0) { | |
857 | if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1, | |
858 | options.user_hostfile2, options.system_hostfile2) == 0) | |
859 | return 0; | |
860 | } | |
861 | return check_host_key(host, hostaddr, host_key, /*readonly*/ 0, | |
862 | options.user_hostfile, options.system_hostfile); | |
95f1eccc | 863 | } |
864 | ||
8ce64345 | 865 | /* |
a306f2dd | 866 | * Starts a dialog with the server, and authenticates the current user on the |
867 | * server. This does not need any extra privileges. The basic connection | |
868 | * to the server must already have been established before this is called. | |
869 | * If login fails, this function prints an error and never returns. | |
870 | * This function does not require super-user privileges. | |
8ce64345 | 871 | */ |
872 | void | |
8002af61 | 873 | ssh_login(Key **keys, int nkeys, const char *orighost, |
63bd8c36 | 874 | struct sockaddr *hostaddr, struct passwd *pw) |
8ce64345 | 875 | { |
a306f2dd | 876 | char *host, *cp; |
8ce64345 | 877 | char *server_user, *local_user; |
8ce64345 | 878 | |
8ce64345 | 879 | local_user = xstrdup(pw->pw_name); |
880 | server_user = options.user ? options.user : local_user; | |
881 | ||
7b2ea3a1 | 882 | /* Convert the user-supplied hostname into all lowercase. */ |
883 | host = xstrdup(orighost); | |
884 | for (cp = host; *cp; cp++) | |
885 | if (isupper(*cp)) | |
886 | *cp = tolower(*cp); | |
887 | ||
888 | /* Exchange protocol version identification strings with the server. */ | |
889 | ssh_exchange_identification(); | |
890 | ||
891 | /* Put the connection into non-blocking mode. */ | |
892 | packet_set_nonblocking(); | |
893 | ||
7b2ea3a1 | 894 | /* key exchange */ |
7b2ea3a1 | 895 | /* authenticate user */ |
8ce64345 | 896 | if (compat20) { |
897 | ssh_kex2(host, hostaddr); | |
8002af61 | 898 | ssh_userauth2(local_user, server_user, host, keys, nkeys); |
8ce64345 | 899 | } else { |
8ce64345 | 900 | ssh_kex(host, hostaddr); |
8002af61 | 901 | ssh_userauth1(local_user, server_user, host, keys, nkeys); |
8ce64345 | 902 | } |
7b2ea3a1 | 903 | } |
0ae4fe1d | 904 | |
905 | void | |
906 | ssh_put_password(char *password) | |
907 | { | |
908 | int size; | |
909 | char *padded; | |
910 | ||
99c415db | 911 | if (datafellows & SSH_BUG_PASSWORDPAD) { |
449c5ba5 | 912 | packet_put_cstring(password); |
99c415db | 913 | return; |
914 | } | |
0ae4fe1d | 915 | size = roundup(strlen(password) + 1, 32); |
916 | padded = xmalloc(size); | |
917 | memset(padded, 0, size); | |
918 | strlcpy(padded, password, size); | |
919 | packet_put_string(padded, size); | |
920 | memset(padded, 0, size); | |
921 | xfree(padded); | |
922 | } |