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3c0ef626 | 1 | /* |
2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * Code to connect to a remote host, and to perform the client side of the | |
6 | * login (authentication) dialog. | |
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". | |
13 | */ | |
14 | ||
15 | #include "includes.h" | |
0fff78ff | 16 | RCSID("$OpenBSD: sshconnect.c,v 1.147 2003/06/29 12:44:38 markus Exp $"); |
3c0ef626 | 17 | |
18 | #include <openssl/bn.h> | |
19 | ||
20 | #include "ssh.h" | |
21 | #include "xmalloc.h" | |
22 | #include "rsa.h" | |
23 | #include "buffer.h" | |
24 | #include "packet.h" | |
25 | #include "uidswap.h" | |
26 | #include "compat.h" | |
27 | #include "key.h" | |
28 | #include "sshconnect.h" | |
29 | #include "hostfile.h" | |
30 | #include "log.h" | |
31 | #include "readconf.h" | |
32 | #include "atomicio.h" | |
33 | #include "misc.h" | |
e9a17296 | 34 | #include "readpass.h" |
3c0ef626 | 35 | |
0fff78ff | 36 | #ifdef DNS |
37 | #include "dns.h" | |
38 | #endif | |
39 | ||
3c0ef626 | 40 | char *client_version_string = NULL; |
41 | char *server_version_string = NULL; | |
42 | ||
0fff78ff | 43 | #ifdef DNS |
44 | int verified_host_key_dns = 0; | |
45 | #endif | |
46 | ||
f5799ae1 | 47 | /* import */ |
3c0ef626 | 48 | extern Options options; |
49 | extern char *__progname; | |
f5799ae1 | 50 | extern uid_t original_real_uid; |
51 | extern uid_t original_effective_uid; | |
41b2f314 | 52 | extern pid_t proxy_command_pid; |
3c0ef626 | 53 | |
54 | #ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */ | |
55 | #define INET6_ADDRSTRLEN 46 | |
56 | #endif | |
57 | ||
41b2f314 | 58 | static int show_other_keys(const char *, Key *); |
3c0ef626 | 59 | |
60 | /* | |
61 | * Connect to the given ssh server using a proxy command. | |
62 | */ | |
63 | static int | |
f5799ae1 | 64 | ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) |
3c0ef626 | 65 | { |
66 | Buffer command; | |
67 | const char *cp; | |
68 | char *command_string; | |
69 | int pin[2], pout[2]; | |
70 | pid_t pid; | |
71 | char strport[NI_MAXSERV]; | |
72 | ||
73 | /* Convert the port number into a string. */ | |
74 | snprintf(strport, sizeof strport, "%hu", port); | |
75 | ||
41b2f314 | 76 | /* |
77 | * Build the final command string in the buffer by making the | |
78 | * appropriate substitutions to the given proxy command. | |
79 | * | |
80 | * Use "exec" to avoid "sh -c" processes on some platforms | |
81 | * (e.g. Solaris) | |
82 | */ | |
3c0ef626 | 83 | buffer_init(&command); |
41b2f314 | 84 | buffer_append(&command, "exec ", 5); |
85 | ||
3c0ef626 | 86 | for (cp = proxy_command; *cp; cp++) { |
87 | if (cp[0] == '%' && cp[1] == '%') { | |
88 | buffer_append(&command, "%", 1); | |
89 | cp++; | |
90 | continue; | |
91 | } | |
92 | if (cp[0] == '%' && cp[1] == 'h') { | |
93 | buffer_append(&command, host, strlen(host)); | |
94 | cp++; | |
95 | continue; | |
96 | } | |
97 | if (cp[0] == '%' && cp[1] == 'p') { | |
98 | buffer_append(&command, strport, strlen(strport)); | |
99 | cp++; | |
100 | continue; | |
101 | } | |
102 | buffer_append(&command, cp, 1); | |
103 | } | |
104 | buffer_append(&command, "\0", 1); | |
105 | ||
106 | /* Get the final command string. */ | |
107 | command_string = buffer_ptr(&command); | |
108 | ||
109 | /* Create pipes for communicating with the proxy. */ | |
110 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
111 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
e9a17296 | 112 | strerror(errno)); |
3c0ef626 | 113 | |
114 | debug("Executing proxy command: %.500s", command_string); | |
115 | ||
116 | /* Fork and execute the proxy command. */ | |
117 | if ((pid = fork()) == 0) { | |
118 | char *argv[10]; | |
119 | ||
120 | /* Child. Permanently give up superuser privileges. */ | |
f5799ae1 | 121 | seteuid(original_real_uid); |
122 | setuid(original_real_uid); | |
3c0ef626 | 123 | |
124 | /* Redirect stdin and stdout. */ | |
125 | close(pin[1]); | |
126 | if (pin[0] != 0) { | |
127 | if (dup2(pin[0], 0) < 0) | |
128 | perror("dup2 stdin"); | |
129 | close(pin[0]); | |
130 | } | |
131 | close(pout[0]); | |
132 | if (dup2(pout[1], 1) < 0) | |
133 | perror("dup2 stdout"); | |
134 | /* Cannot be 1 because pin allocated two descriptors. */ | |
135 | close(pout[1]); | |
136 | ||
137 | /* Stderr is left as it is so that error messages get | |
138 | printed on the user's terminal. */ | |
139 | argv[0] = _PATH_BSHELL; | |
140 | argv[1] = "-c"; | |
141 | argv[2] = command_string; | |
142 | argv[3] = NULL; | |
143 | ||
144 | /* Execute the proxy command. Note that we gave up any | |
145 | extra privileges above. */ | |
146 | execv(argv[0], argv); | |
147 | perror(argv[0]); | |
148 | exit(1); | |
149 | } | |
150 | /* Parent. */ | |
151 | if (pid < 0) | |
152 | fatal("fork failed: %.100s", strerror(errno)); | |
41b2f314 | 153 | else |
154 | proxy_command_pid = pid; /* save pid to clean up later */ | |
3c0ef626 | 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]); | |
165 | ||
166 | /* Indicate OK return */ | |
167 | return 0; | |
168 | } | |
169 | ||
170 | /* | |
171 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
172 | */ | |
173 | static int | |
0fff78ff | 174 | ssh_create_socket(int privileged, struct addrinfo *ai) |
3c0ef626 | 175 | { |
176 | int sock, gaierr; | |
177 | struct addrinfo hints, *res; | |
178 | ||
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 | */ | |
183 | if (privileged) { | |
184 | int p = IPPORT_RESERVED - 1; | |
f5799ae1 | 185 | PRIV_START; |
0fff78ff | 186 | sock = rresvport_af(&p, ai->ai_family); |
f5799ae1 | 187 | PRIV_END; |
3c0ef626 | 188 | if (sock < 0) |
0fff78ff | 189 | error("rresvport: af=%d %.100s", ai->ai_family, |
190 | strerror(errno)); | |
3c0ef626 | 191 | else |
192 | debug("Allocated local port %d.", p); | |
193 | return sock; | |
194 | } | |
0fff78ff | 195 | sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); |
3c0ef626 | 196 | if (sock < 0) |
197 | error("socket: %.100s", strerror(errno)); | |
3c0ef626 | 198 | |
199 | /* Bind the socket to an alternative local IP address */ | |
200 | if (options.bind_address == NULL) | |
201 | return sock; | |
202 | ||
203 | memset(&hints, 0, sizeof(hints)); | |
0fff78ff | 204 | hints.ai_family = ai->ai_family; |
205 | hints.ai_socktype = ai->ai_socktype; | |
206 | hints.ai_protocol = ai->ai_protocol; | |
3c0ef626 | 207 | hints.ai_flags = AI_PASSIVE; |
208 | gaierr = getaddrinfo(options.bind_address, "0", &hints, &res); | |
209 | if (gaierr) { | |
210 | error("getaddrinfo: %s: %s", options.bind_address, | |
211 | gai_strerror(gaierr)); | |
212 | close(sock); | |
213 | return -1; | |
214 | } | |
215 | if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { | |
216 | error("bind: %s: %s", options.bind_address, strerror(errno)); | |
217 | close(sock); | |
218 | freeaddrinfo(res); | |
219 | return -1; | |
220 | } | |
221 | freeaddrinfo(res); | |
222 | return sock; | |
223 | } | |
224 | ||
0fff78ff | 225 | static int |
226 | timeout_connect(int sockfd, const struct sockaddr *serv_addr, | |
227 | socklen_t addrlen, int timeout) | |
228 | { | |
229 | fd_set *fdset; | |
230 | struct timeval tv; | |
231 | socklen_t optlen; | |
232 | int fdsetsz, optval, rc, result = -1; | |
233 | ||
234 | if (timeout <= 0) | |
235 | return (connect(sockfd, serv_addr, addrlen)); | |
236 | ||
237 | if (fcntl(sockfd, F_SETFL, O_NONBLOCK) < 0) | |
238 | return (-1); | |
239 | ||
240 | rc = connect(sockfd, serv_addr, addrlen); | |
241 | if (rc == 0) | |
242 | return (0); | |
243 | if (errno != EINPROGRESS) | |
244 | return (-1); | |
245 | ||
246 | fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask); | |
247 | fdset = (fd_set *)xmalloc(fdsetsz); | |
248 | ||
249 | memset(fdset, 0, fdsetsz); | |
250 | FD_SET(sockfd, fdset); | |
251 | tv.tv_sec = timeout; | |
252 | tv.tv_usec = 0; | |
253 | ||
254 | for(;;) { | |
255 | rc = select(sockfd + 1, NULL, fdset, NULL, &tv); | |
256 | if (rc != -1 || errno != EINTR) | |
257 | break; | |
258 | } | |
259 | ||
260 | switch(rc) { | |
261 | case 0: | |
262 | /* Timed out */ | |
263 | errno = ETIMEDOUT; | |
264 | break; | |
265 | case -1: | |
266 | /* Select error */ | |
267 | debug("select: %s", strerror(errno)); | |
268 | break; | |
269 | case 1: | |
270 | /* Completed or failed */ | |
271 | optval = 0; | |
272 | optlen = sizeof(optval); | |
273 | if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, | |
274 | &optlen) == -1) | |
275 | debug("getsockopt: %s", strerror(errno)); | |
276 | break; | |
277 | if (optval != 0) { | |
278 | errno = optval; | |
279 | break; | |
280 | } | |
281 | result = 0; | |
282 | break; | |
283 | default: | |
284 | /* Should not occur */ | |
285 | fatal("Bogus return (%d) from select()", rc); | |
286 | } | |
287 | ||
288 | xfree(fdset); | |
289 | return (result); | |
290 | } | |
291 | ||
3c0ef626 | 292 | /* |
293 | * Opens a TCP/IP connection to the remote server on the given host. | |
294 | * The address of the remote host will be returned in hostaddr. | |
f5799ae1 | 295 | * If port is 0, the default port will be used. If needpriv is true, |
3c0ef626 | 296 | * a privileged port will be allocated to make the connection. |
f5799ae1 | 297 | * This requires super-user privileges if needpriv is true. |
3c0ef626 | 298 | * Connection_attempts specifies the maximum number of tries (one per |
299 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
300 | * and %p substituted for host and port, respectively) to use to contact | |
301 | * the daemon. | |
302 | * Return values: | |
303 | * 0 for OK | |
304 | * ECONNREFUSED if we got a "Connection Refused" by the peer on any address | |
305 | * ECONNABORTED if we failed without a "Connection refused" | |
306 | * Suitable error messages for the connection failure will already have been | |
307 | * printed. | |
308 | */ | |
309 | int | |
310 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, | |
311 | u_short port, int family, int connection_attempts, | |
f5799ae1 | 312 | int needpriv, const char *proxy_command) |
3c0ef626 | 313 | { |
314 | int gaierr; | |
315 | int on = 1; | |
316 | int sock = -1, attempt; | |
317 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
318 | struct addrinfo hints, *ai, *aitop; | |
3c0ef626 | 319 | struct servent *sp; |
320 | /* | |
321 | * Did we get only other errors than "Connection refused" (which | |
322 | * should block fallback to rsh and similar), or did we get at least | |
323 | * one "Connection refused"? | |
324 | */ | |
325 | int full_failure = 1; | |
326 | ||
6a9b3198 | 327 | debug2("ssh_connect: needpriv %d", needpriv); |
3c0ef626 | 328 | |
329 | /* Get default port if port has not been set. */ | |
330 | if (port == 0) { | |
331 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
332 | if (sp) | |
333 | port = ntohs(sp->s_port); | |
334 | else | |
335 | port = SSH_DEFAULT_PORT; | |
336 | } | |
337 | /* If a proxy command is given, connect using it. */ | |
338 | if (proxy_command != NULL) | |
f5799ae1 | 339 | return ssh_proxy_connect(host, port, proxy_command); |
3c0ef626 | 340 | |
341 | /* No proxy command. */ | |
342 | ||
343 | memset(&hints, 0, sizeof(hints)); | |
344 | hints.ai_family = family; | |
345 | hints.ai_socktype = SOCK_STREAM; | |
680cee3b | 346 | snprintf(strport, sizeof strport, "%u", port); |
3c0ef626 | 347 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) |
348 | fatal("%s: %.100s: %s", __progname, host, | |
349 | gai_strerror(gaierr)); | |
350 | ||
351 | /* | |
352 | * Try to connect several times. On some machines, the first time | |
353 | * will sometimes fail. In general socket code appears to behave | |
354 | * quite magically on many machines. | |
355 | */ | |
356 | for (attempt = 0; ;) { | |
357 | if (attempt > 0) | |
358 | debug("Trying again..."); | |
359 | ||
360 | /* Loop through addresses for this host, and try each one in | |
361 | sequence until the connection succeeds. */ | |
362 | for (ai = aitop; ai; ai = ai->ai_next) { | |
363 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
364 | continue; | |
365 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
366 | ntop, sizeof(ntop), strport, sizeof(strport), | |
367 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
368 | error("ssh_connect: getnameinfo failed"); | |
369 | continue; | |
370 | } | |
371 | debug("Connecting to %.200s [%.100s] port %s.", | |
372 | host, ntop, strport); | |
373 | ||
374 | /* Create a socket for connecting. */ | |
0fff78ff | 375 | sock = ssh_create_socket(needpriv, ai); |
3c0ef626 | 376 | if (sock < 0) |
377 | /* Any error is already output */ | |
378 | continue; | |
379 | ||
0fff78ff | 380 | if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, |
381 | options.connection_timeout) >= 0) { | |
3c0ef626 | 382 | /* Successful connection. */ |
383 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); | |
3c0ef626 | 384 | break; |
385 | } else { | |
386 | if (errno == ECONNREFUSED) | |
387 | full_failure = 0; | |
41b2f314 | 388 | debug("connect to address %s port %s: %s", |
389 | ntop, strport, strerror(errno)); | |
3c0ef626 | 390 | /* |
391 | * Close the failed socket; there appear to | |
392 | * be some problems when reusing a socket for | |
393 | * which connect() has already returned an | |
394 | * error. | |
395 | */ | |
3c0ef626 | 396 | close(sock); |
397 | } | |
398 | } | |
399 | if (ai) | |
400 | break; /* Successful connection. */ | |
401 | ||
402 | attempt++; | |
403 | if (attempt >= connection_attempts) | |
404 | break; | |
405 | /* Sleep a moment before retrying. */ | |
406 | sleep(1); | |
407 | } | |
408 | ||
409 | freeaddrinfo(aitop); | |
410 | ||
411 | /* Return failure if we didn't get a successful connection. */ | |
41b2f314 | 412 | if (attempt >= connection_attempts) { |
0fff78ff | 413 | logit("ssh: connect to host %s port %s: %s", |
41b2f314 | 414 | host, strport, strerror(errno)); |
3c0ef626 | 415 | return full_failure ? ECONNABORTED : ECONNREFUSED; |
41b2f314 | 416 | } |
3c0ef626 | 417 | |
418 | debug("Connection established."); | |
419 | ||
3c0ef626 | 420 | /* Set keepalives if requested. */ |
421 | if (options.keepalives && | |
422 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, | |
423 | sizeof(on)) < 0) | |
424 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
425 | ||
426 | /* Set the connection. */ | |
427 | packet_set_connection(sock, sock); | |
428 | ||
429 | return 0; | |
430 | } | |
431 | ||
432 | /* | |
433 | * Waits for the server identification string, and sends our own | |
434 | * identification string. | |
435 | */ | |
436 | static void | |
437 | ssh_exchange_identification(void) | |
438 | { | |
439 | char buf[256], remote_version[256]; /* must be same size! */ | |
440 | int remote_major, remote_minor, i, mismatch; | |
441 | int connection_in = packet_get_connection_in(); | |
442 | int connection_out = packet_get_connection_out(); | |
443 | int minor1 = PROTOCOL_MINOR_1; | |
444 | ||
445 | /* Read other side\'s version identification. */ | |
446 | for (;;) { | |
447 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
448 | int len = atomicio(read, connection_in, &buf[i], 1); | |
449 | if (len < 0) | |
450 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); | |
451 | if (len != 1) | |
452 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
453 | if (buf[i] == '\r') { | |
454 | buf[i] = '\n'; | |
455 | buf[i + 1] = 0; | |
456 | continue; /**XXX wait for \n */ | |
457 | } | |
458 | if (buf[i] == '\n') { | |
459 | buf[i + 1] = 0; | |
460 | break; | |
461 | } | |
462 | } | |
463 | buf[sizeof(buf) - 1] = 0; | |
464 | if (strncmp(buf, "SSH-", 4) == 0) | |
465 | break; | |
466 | debug("ssh_exchange_identification: %s", buf); | |
467 | } | |
468 | server_version_string = xstrdup(buf); | |
469 | ||
470 | /* | |
471 | * Check that the versions match. In future this might accept | |
472 | * several versions and set appropriate flags to handle them. | |
473 | */ | |
474 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", | |
475 | &remote_major, &remote_minor, remote_version) != 3) | |
476 | fatal("Bad remote protocol version identification: '%.100s'", buf); | |
477 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
e9a17296 | 478 | remote_major, remote_minor, remote_version); |
3c0ef626 | 479 | |
480 | compat_datafellows(remote_version); | |
481 | mismatch = 0; | |
482 | ||
e9a17296 | 483 | switch (remote_major) { |
3c0ef626 | 484 | case 1: |
485 | if (remote_minor == 99 && | |
486 | (options.protocol & SSH_PROTO_2) && | |
487 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
488 | enable_compat20(); | |
489 | break; | |
490 | } | |
491 | if (!(options.protocol & SSH_PROTO_1)) { | |
492 | mismatch = 1; | |
493 | break; | |
494 | } | |
495 | if (remote_minor < 3) { | |
496 | fatal("Remote machine has too old SSH software version."); | |
497 | } else if (remote_minor == 3 || remote_minor == 4) { | |
498 | /* We speak 1.3, too. */ | |
499 | enable_compat13(); | |
500 | minor1 = 3; | |
501 | if (options.forward_agent) { | |
0fff78ff | 502 | logit("Agent forwarding disabled for protocol 1.3"); |
3c0ef626 | 503 | options.forward_agent = 0; |
504 | } | |
505 | } | |
506 | break; | |
507 | case 2: | |
508 | if (options.protocol & SSH_PROTO_2) { | |
509 | enable_compat20(); | |
510 | break; | |
511 | } | |
512 | /* FALLTHROUGH */ | |
513 | default: | |
514 | mismatch = 1; | |
515 | break; | |
516 | } | |
517 | if (mismatch) | |
518 | fatal("Protocol major versions differ: %d vs. %d", | |
519 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, | |
520 | remote_major); | |
521 | /* Send our own protocol version identification. */ | |
522 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
523 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, | |
524 | compat20 ? PROTOCOL_MINOR_2 : minor1, | |
525 | SSH_VERSION); | |
0fff78ff | 526 | if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf)) |
3c0ef626 | 527 | fatal("write: %.100s", strerror(errno)); |
528 | client_version_string = xstrdup(buf); | |
529 | chop(client_version_string); | |
530 | chop(server_version_string); | |
531 | debug("Local version string %.100s", client_version_string); | |
532 | } | |
533 | ||
534 | /* defaults to 'no' */ | |
535 | static int | |
536 | confirm(const char *prompt) | |
537 | { | |
e9a17296 | 538 | const char *msg, *again = "Please type 'yes' or 'no': "; |
539 | char *p; | |
540 | int ret = -1; | |
3c0ef626 | 541 | |
542 | if (options.batch_mode) | |
543 | return 0; | |
e9a17296 | 544 | for (msg = prompt;;msg = again) { |
545 | p = read_passphrase(msg, RP_ECHO); | |
546 | if (p == NULL || | |
547 | (p[0] == '\0') || (p[0] == '\n') || | |
548 | strncasecmp(p, "no", 2) == 0) | |
549 | ret = 0; | |
41b2f314 | 550 | if (p && strncasecmp(p, "yes", 3) == 0) |
e9a17296 | 551 | ret = 1; |
552 | if (p) | |
553 | xfree(p); | |
554 | if (ret != -1) | |
555 | return ret; | |
3c0ef626 | 556 | } |
557 | } | |
558 | ||
559 | /* | |
560 | * check whether the supplied host key is valid, return -1 if the key | |
561 | * is not valid. the user_hostfile will not be updated if 'readonly' is true. | |
562 | */ | |
3c0ef626 | 563 | static int |
564 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, | |
565 | int readonly, const char *user_hostfile, const char *system_hostfile) | |
566 | { | |
567 | Key *file_key; | |
568 | char *type = key_type(host_key); | |
569 | char *ip = NULL; | |
570 | char hostline[1000], *hostp, *fp; | |
571 | HostStatus host_status; | |
572 | HostStatus ip_status; | |
573 | int local = 0, host_ip_differ = 0; | |
574 | int salen; | |
575 | char ntop[NI_MAXHOST]; | |
e9a17296 | 576 | char msg[1024]; |
0fff78ff | 577 | int len, host_line, ip_line; |
3c0ef626 | 578 | const char *host_file = NULL, *ip_file = NULL; |
579 | ||
580 | /* | |
581 | * Force accepting of the host key for loopback/localhost. The | |
582 | * problem is that if the home directory is NFS-mounted to multiple | |
583 | * machines, localhost will refer to a different machine in each of | |
584 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
585 | * essentially disables host authentication for localhost; however, | |
586 | * this is probably not a real problem. | |
587 | */ | |
588 | /** hostaddr == 0! */ | |
589 | switch (hostaddr->sa_family) { | |
590 | case AF_INET: | |
591 | local = (ntohl(((struct sockaddr_in *)hostaddr)-> | |
e9a17296 | 592 | sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; |
3c0ef626 | 593 | salen = sizeof(struct sockaddr_in); |
594 | break; | |
595 | case AF_INET6: | |
596 | local = IN6_IS_ADDR_LOOPBACK( | |
597 | &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
598 | salen = sizeof(struct sockaddr_in6); | |
599 | break; | |
600 | default: | |
601 | local = 0; | |
602 | salen = sizeof(struct sockaddr_storage); | |
603 | break; | |
604 | } | |
605 | if (options.no_host_authentication_for_localhost == 1 && local && | |
606 | options.host_key_alias == NULL) { | |
607 | debug("Forcing accepting of host key for " | |
608 | "loopback/localhost."); | |
609 | return 0; | |
610 | } | |
611 | ||
612 | /* | |
613 | * We don't have the remote ip-address for connections | |
614 | * using a proxy command | |
615 | */ | |
616 | if (options.proxy_command == NULL) { | |
617 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), | |
618 | NULL, 0, NI_NUMERICHOST) != 0) | |
619 | fatal("check_host_key: getnameinfo failed"); | |
620 | ip = xstrdup(ntop); | |
621 | } else { | |
622 | ip = xstrdup("<no hostip for proxy command>"); | |
623 | } | |
624 | /* | |
625 | * Turn off check_host_ip if the connection is to localhost, via proxy | |
626 | * command or if we don't have a hostname to compare with | |
627 | */ | |
628 | if (options.check_host_ip && | |
629 | (local || strcmp(host, ip) == 0 || options.proxy_command != NULL)) | |
630 | options.check_host_ip = 0; | |
631 | ||
632 | /* | |
633 | * Allow the user to record the key under a different name. This is | |
634 | * useful for ssh tunneling over forwarded connections or if you run | |
635 | * multiple sshd's on different ports on the same machine. | |
636 | */ | |
637 | if (options.host_key_alias != NULL) { | |
638 | host = options.host_key_alias; | |
639 | debug("using hostkeyalias: %s", host); | |
640 | } | |
641 | ||
642 | /* | |
643 | * Store the host key from the known host file in here so that we can | |
644 | * compare it with the key for the IP address. | |
645 | */ | |
646 | file_key = key_new(host_key->type); | |
647 | ||
648 | /* | |
649 | * Check if the host key is present in the user\'s list of known | |
650 | * hosts or in the systemwide list. | |
651 | */ | |
652 | host_file = user_hostfile; | |
653 | host_status = check_host_in_hostfile(host_file, host, host_key, | |
e9a17296 | 654 | file_key, &host_line); |
3c0ef626 | 655 | if (host_status == HOST_NEW) { |
656 | host_file = system_hostfile; | |
657 | host_status = check_host_in_hostfile(host_file, host, host_key, | |
658 | file_key, &host_line); | |
659 | } | |
660 | /* | |
661 | * Also perform check for the ip address, skip the check if we are | |
662 | * localhost or the hostname was an ip address to begin with | |
663 | */ | |
664 | if (options.check_host_ip) { | |
665 | Key *ip_key = key_new(host_key->type); | |
666 | ||
667 | ip_file = user_hostfile; | |
668 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, | |
669 | ip_key, &ip_line); | |
670 | if (ip_status == HOST_NEW) { | |
671 | ip_file = system_hostfile; | |
672 | ip_status = check_host_in_hostfile(ip_file, ip, | |
673 | host_key, ip_key, &ip_line); | |
674 | } | |
675 | if (host_status == HOST_CHANGED && | |
676 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) | |
677 | host_ip_differ = 1; | |
678 | ||
679 | key_free(ip_key); | |
680 | } else | |
681 | ip_status = host_status; | |
682 | ||
683 | key_free(file_key); | |
684 | ||
685 | switch (host_status) { | |
686 | case HOST_OK: | |
687 | /* The host is known and the key matches. */ | |
688 | debug("Host '%.200s' is known and matches the %s host key.", | |
689 | host, type); | |
690 | debug("Found key in %s:%d", host_file, host_line); | |
691 | if (options.check_host_ip && ip_status == HOST_NEW) { | |
692 | if (readonly) | |
0fff78ff | 693 | logit("%s host key for IP address " |
3c0ef626 | 694 | "'%.128s' not in list of known hosts.", |
695 | type, ip); | |
696 | else if (!add_host_to_hostfile(user_hostfile, ip, | |
e9a17296 | 697 | host_key)) |
0fff78ff | 698 | logit("Failed to add the %s host key for IP " |
3c0ef626 | 699 | "address '%.128s' to the list of known " |
700 | "hosts (%.30s).", type, ip, user_hostfile); | |
701 | else | |
0fff78ff | 702 | logit("Warning: Permanently added the %s host " |
3c0ef626 | 703 | "key for IP address '%.128s' to the list " |
704 | "of known hosts.", type, ip); | |
705 | } | |
706 | break; | |
707 | case HOST_NEW: | |
708 | if (readonly) | |
709 | goto fail; | |
710 | /* The host is new. */ | |
711 | if (options.strict_host_key_checking == 1) { | |
712 | /* | |
713 | * User has requested strict host key checking. We | |
714 | * will not add the host key automatically. The only | |
715 | * alternative left is to abort. | |
716 | */ | |
717 | error("No %s host key is known for %.200s and you " | |
718 | "have requested strict checking.", type, host); | |
719 | goto fail; | |
720 | } else if (options.strict_host_key_checking == 2) { | |
0fff78ff | 721 | char msg1[1024], msg2[1024]; |
722 | ||
723 | if (show_other_keys(host, host_key)) | |
724 | snprintf(msg1, sizeof(msg1), | |
725 | "\nbut keys of different type are already" | |
726 | " known for this host."); | |
727 | else | |
728 | snprintf(msg1, sizeof(msg1), "."); | |
3c0ef626 | 729 | /* The default */ |
3c0ef626 | 730 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
0fff78ff | 731 | msg2[0] = '\0'; |
732 | #ifdef DNS | |
733 | if (options.verify_host_key_dns) { | |
734 | if (verified_host_key_dns) | |
735 | snprintf(msg2, sizeof(msg2), | |
736 | "Matching host key fingerprint" | |
737 | " found in DNS.\n"); | |
738 | else | |
739 | snprintf(msg2, sizeof(msg2), | |
740 | "No matching host key fingerprint" | |
741 | " found in DNS.\n"); | |
742 | } | |
743 | #endif | |
e9a17296 | 744 | snprintf(msg, sizeof(msg), |
3c0ef626 | 745 | "The authenticity of host '%.200s (%s)' can't be " |
41b2f314 | 746 | "established%s\n" |
0fff78ff | 747 | "%s key fingerprint is %s.\n%s" |
3c0ef626 | 748 | "Are you sure you want to continue connecting " |
41b2f314 | 749 | "(yes/no)? ", |
0fff78ff | 750 | host, ip, msg1, type, fp, msg2); |
3c0ef626 | 751 | xfree(fp); |
e9a17296 | 752 | if (!confirm(msg)) |
3c0ef626 | 753 | goto fail; |
3c0ef626 | 754 | } |
755 | if (options.check_host_ip && ip_status == HOST_NEW) { | |
756 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); | |
757 | hostp = hostline; | |
758 | } else | |
759 | hostp = host; | |
760 | ||
761 | /* | |
762 | * If not in strict mode, add the key automatically to the | |
763 | * local known_hosts file. | |
764 | */ | |
765 | if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) | |
0fff78ff | 766 | logit("Failed to add the host to the list of known " |
3c0ef626 | 767 | "hosts (%.500s).", user_hostfile); |
768 | else | |
0fff78ff | 769 | logit("Warning: Permanently added '%.200s' (%s) to the " |
3c0ef626 | 770 | "list of known hosts.", hostp, type); |
771 | break; | |
772 | case HOST_CHANGED: | |
773 | if (options.check_host_ip && host_ip_differ) { | |
774 | char *msg; | |
775 | if (ip_status == HOST_NEW) | |
776 | msg = "is unknown"; | |
777 | else if (ip_status == HOST_OK) | |
778 | msg = "is unchanged"; | |
779 | else | |
780 | msg = "has a different value"; | |
781 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
782 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
783 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
784 | error("The %s host key for %s has changed,", type, host); | |
785 | error("and the key for the according IP address %s", ip); | |
786 | error("%s. This could either mean that", msg); | |
787 | error("DNS SPOOFING is happening or the IP address for the host"); | |
788 | error("and its host key have changed at the same time."); | |
789 | if (ip_status != HOST_NEW) | |
790 | error("Offending key for IP in %s:%d", ip_file, ip_line); | |
791 | } | |
792 | /* The host key has changed. */ | |
793 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); | |
794 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
795 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); | |
796 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
797 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
798 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
799 | error("It is also possible that the %s host key has just been changed.", type); | |
800 | error("The fingerprint for the %s key sent by the remote host is\n%s.", | |
801 | type, fp); | |
802 | error("Please contact your system administrator."); | |
803 | error("Add correct host key in %.100s to get rid of this message.", | |
804 | user_hostfile); | |
805 | error("Offending key in %s:%d", host_file, host_line); | |
806 | xfree(fp); | |
807 | ||
808 | /* | |
809 | * If strict host key checking is in use, the user will have | |
810 | * to edit the key manually and we can only abort. | |
811 | */ | |
812 | if (options.strict_host_key_checking) { | |
813 | error("%s host key for %.200s has changed and you have " | |
814 | "requested strict checking.", type, host); | |
815 | goto fail; | |
816 | } | |
817 | ||
818 | /* | |
819 | * If strict host key checking has not been requested, allow | |
0fff78ff | 820 | * the connection but without MITM-able authentication or |
3c0ef626 | 821 | * agent forwarding. |
822 | */ | |
823 | if (options.password_authentication) { | |
824 | error("Password authentication is disabled to avoid " | |
825 | "man-in-the-middle attacks."); | |
826 | options.password_authentication = 0; | |
827 | } | |
0fff78ff | 828 | if (options.kbd_interactive_authentication) { |
829 | error("Keyboard-interactive authentication is disabled" | |
830 | " to avoid man-in-the-middle attacks."); | |
831 | options.kbd_interactive_authentication = 0; | |
832 | options.challenge_response_authentication = 0; | |
833 | } | |
834 | if (options.challenge_response_authentication) { | |
835 | error("Challenge/response authentication is disabled" | |
836 | " to avoid man-in-the-middle attacks."); | |
837 | options.challenge_response_authentication = 0; | |
838 | } | |
3c0ef626 | 839 | if (options.forward_agent) { |
840 | error("Agent forwarding is disabled to avoid " | |
841 | "man-in-the-middle attacks."); | |
842 | options.forward_agent = 0; | |
843 | } | |
844 | if (options.forward_x11) { | |
845 | error("X11 forwarding is disabled to avoid " | |
846 | "man-in-the-middle attacks."); | |
847 | options.forward_x11 = 0; | |
848 | } | |
849 | if (options.num_local_forwards > 0 || | |
850 | options.num_remote_forwards > 0) { | |
851 | error("Port forwarding is disabled to avoid " | |
852 | "man-in-the-middle attacks."); | |
853 | options.num_local_forwards = | |
e9a17296 | 854 | options.num_remote_forwards = 0; |
3c0ef626 | 855 | } |
856 | /* | |
857 | * XXX Should permit the user to change to use the new id. | |
858 | * This could be done by converting the host key to an | |
859 | * identifying sentence, tell that the host identifies itself | |
860 | * by that sentence, and ask the user if he/she whishes to | |
861 | * accept the authentication. | |
862 | */ | |
863 | break; | |
41b2f314 | 864 | case HOST_FOUND: |
865 | fatal("internal error"); | |
866 | break; | |
3c0ef626 | 867 | } |
868 | ||
869 | if (options.check_host_ip && host_status != HOST_CHANGED && | |
870 | ip_status == HOST_CHANGED) { | |
e9a17296 | 871 | snprintf(msg, sizeof(msg), |
872 | "Warning: the %s host key for '%.200s' " | |
873 | "differs from the key for the IP address '%.128s'" | |
874 | "\nOffending key for IP in %s:%d", | |
875 | type, host, ip, ip_file, ip_line); | |
876 | if (host_status == HOST_OK) { | |
877 | len = strlen(msg); | |
878 | snprintf(msg + len, sizeof(msg) - len, | |
879 | "\nMatching host key in %s:%d", | |
f5799ae1 | 880 | host_file, host_line); |
e9a17296 | 881 | } |
3c0ef626 | 882 | if (options.strict_host_key_checking == 1) { |
0fff78ff | 883 | logit("%s", msg); |
3c0ef626 | 884 | error("Exiting, you have requested strict checking."); |
885 | goto fail; | |
886 | } else if (options.strict_host_key_checking == 2) { | |
e9a17296 | 887 | strlcat(msg, "\nAre you sure you want " |
888 | "to continue connecting (yes/no)? ", sizeof(msg)); | |
889 | if (!confirm(msg)) | |
3c0ef626 | 890 | goto fail; |
e9a17296 | 891 | } else { |
0fff78ff | 892 | logit("%s", msg); |
3c0ef626 | 893 | } |
894 | } | |
895 | ||
896 | xfree(ip); | |
897 | return 0; | |
898 | ||
899 | fail: | |
900 | xfree(ip); | |
901 | return -1; | |
902 | } | |
903 | ||
0fff78ff | 904 | /* returns 0 if key verifies or -1 if key does NOT verify */ |
3c0ef626 | 905 | int |
906 | verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) | |
907 | { | |
908 | struct stat st; | |
909 | ||
0fff78ff | 910 | #ifdef DNS |
911 | if (options.verify_host_key_dns) { | |
912 | switch(verify_host_key_dns(host, hostaddr, host_key)) { | |
913 | case DNS_VERIFY_OK: | |
914 | #ifdef DNSSEC | |
915 | return 0; | |
916 | #else | |
917 | verified_host_key_dns = 1; | |
918 | break; | |
919 | #endif | |
920 | case DNS_VERIFY_FAILED: | |
921 | return -1; | |
922 | case DNS_VERIFY_ERROR: | |
923 | break; | |
924 | default: | |
925 | debug3("bad return value from verify_host_key_dns"); | |
926 | break; | |
927 | } | |
928 | } | |
929 | #endif /* DNS */ | |
930 | ||
3c0ef626 | 931 | /* return ok if the key can be found in an old keyfile */ |
932 | if (stat(options.system_hostfile2, &st) == 0 || | |
933 | stat(options.user_hostfile2, &st) == 0) { | |
934 | if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1, | |
935 | options.user_hostfile2, options.system_hostfile2) == 0) | |
936 | return 0; | |
937 | } | |
938 | return check_host_key(host, hostaddr, host_key, /*readonly*/ 0, | |
939 | options.user_hostfile, options.system_hostfile); | |
940 | } | |
941 | ||
942 | /* | |
943 | * Starts a dialog with the server, and authenticates the current user on the | |
944 | * server. This does not need any extra privileges. The basic connection | |
945 | * to the server must already have been established before this is called. | |
946 | * If login fails, this function prints an error and never returns. | |
947 | * This function does not require super-user privileges. | |
948 | */ | |
949 | void | |
f5799ae1 | 950 | ssh_login(Sensitive *sensitive, const char *orighost, |
3c0ef626 | 951 | struct sockaddr *hostaddr, struct passwd *pw) |
952 | { | |
953 | char *host, *cp; | |
954 | char *server_user, *local_user; | |
955 | ||
956 | local_user = xstrdup(pw->pw_name); | |
957 | server_user = options.user ? options.user : local_user; | |
958 | ||
959 | /* Convert the user-supplied hostname into all lowercase. */ | |
960 | host = xstrdup(orighost); | |
961 | for (cp = host; *cp; cp++) | |
962 | if (isupper(*cp)) | |
963 | *cp = tolower(*cp); | |
964 | ||
965 | /* Exchange protocol version identification strings with the server. */ | |
966 | ssh_exchange_identification(); | |
967 | ||
968 | /* Put the connection into non-blocking mode. */ | |
969 | packet_set_nonblocking(); | |
970 | ||
971 | /* key exchange */ | |
972 | /* authenticate user */ | |
973 | if (compat20) { | |
974 | ssh_kex2(host, hostaddr); | |
f5799ae1 | 975 | ssh_userauth2(local_user, server_user, host, sensitive); |
3c0ef626 | 976 | } else { |
977 | ssh_kex(host, hostaddr); | |
f5799ae1 | 978 | ssh_userauth1(local_user, server_user, host, sensitive); |
3c0ef626 | 979 | } |
980 | } | |
981 | ||
982 | void | |
983 | ssh_put_password(char *password) | |
984 | { | |
985 | int size; | |
986 | char *padded; | |
987 | ||
988 | if (datafellows & SSH_BUG_PASSWORDPAD) { | |
989 | packet_put_cstring(password); | |
990 | return; | |
991 | } | |
992 | size = roundup(strlen(password) + 1, 32); | |
993 | padded = xmalloc(size); | |
994 | memset(padded, 0, size); | |
995 | strlcpy(padded, password, size); | |
996 | packet_put_string(padded, size); | |
997 | memset(padded, 0, size); | |
998 | xfree(padded); | |
999 | } | |
41b2f314 | 1000 | |
1001 | static int | |
1002 | show_key_from_file(const char *file, const char *host, int keytype) | |
1003 | { | |
1004 | Key *found; | |
1005 | char *fp; | |
1006 | int line, ret; | |
1007 | ||
1008 | found = key_new(keytype); | |
1009 | if ((ret = lookup_key_in_hostfile_by_type(file, host, | |
1010 | keytype, found, &line))) { | |
1011 | fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX); | |
0fff78ff | 1012 | logit("WARNING: %s key found for host %s\n" |
41b2f314 | 1013 | "in %s:%d\n" |
1014 | "%s key fingerprint %s.", | |
1015 | key_type(found), host, file, line, | |
1016 | key_type(found), fp); | |
1017 | xfree(fp); | |
1018 | } | |
1019 | key_free(found); | |
1020 | return (ret); | |
1021 | } | |
1022 | ||
1023 | /* print all known host keys for a given host, but skip keys of given type */ | |
1024 | static int | |
1025 | show_other_keys(const char *host, Key *key) | |
1026 | { | |
1027 | int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1}; | |
1028 | int i, found = 0; | |
1029 | ||
1030 | for (i = 0; type[i] != -1; i++) { | |
1031 | if (type[i] == key->type) | |
1032 | continue; | |
1033 | if (type[i] != KEY_RSA1 && | |
1034 | show_key_from_file(options.user_hostfile2, host, type[i])) { | |
1035 | found = 1; | |
1036 | continue; | |
1037 | } | |
1038 | if (type[i] != KEY_RSA1 && | |
1039 | show_key_from_file(options.system_hostfile2, host, type[i])) { | |
1040 | found = 1; | |
1041 | continue; | |
1042 | } | |
1043 | if (show_key_from_file(options.user_hostfile, host, type[i])) { | |
1044 | found = 1; | |
1045 | continue; | |
1046 | } | |
1047 | if (show_key_from_file(options.system_hostfile, host, type[i])) { | |
1048 | found = 1; | |
1049 | continue; | |
1050 | } | |
1051 | debug2("no key of type %d for host %s", type[i], host); | |
1052 | } | |
1053 | return (found); | |
1054 | } |