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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" | |
08822d99 | 16 | RCSID("$OpenBSD: sshconnect.c,v 1.171 2005/12/06 22:38:27 reyk 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" | |
473db5ab | 34 | #include "dns.h" |
35 | ||
3c0ef626 | 36 | char *client_version_string = NULL; |
37 | char *server_version_string = NULL; | |
38 | ||
08822d99 | 39 | static int matching_host_key_dns = 0; |
473db5ab | 40 | |
41 | /* import */ | |
3c0ef626 | 42 | extern Options options; |
43 | extern char *__progname; | |
473db5ab | 44 | extern uid_t original_real_uid; |
45 | extern uid_t original_effective_uid; | |
46 | extern pid_t proxy_command_pid; | |
3c0ef626 | 47 | |
48 | #ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */ | |
49 | #define INET6_ADDRSTRLEN 46 | |
50 | #endif | |
51 | ||
473db5ab | 52 | static int show_other_keys(const char *, Key *); |
53 | static void warn_changed_key(Key *); | |
3c0ef626 | 54 | |
55 | /* | |
56 | * Connect to the given ssh server using a proxy command. | |
57 | */ | |
58 | static int | |
473db5ab | 59 | ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) |
3c0ef626 | 60 | { |
473db5ab | 61 | char *command_string, *tmp; |
3c0ef626 | 62 | int pin[2], pout[2]; |
63 | pid_t pid; | |
64 | char strport[NI_MAXSERV]; | |
473db5ab | 65 | size_t len; |
3c0ef626 | 66 | |
67 | /* Convert the port number into a string. */ | |
68 | snprintf(strport, sizeof strport, "%hu", port); | |
69 | ||
473db5ab | 70 | /* |
71 | * Build the final command string in the buffer by making the | |
72 | * appropriate substitutions to the given proxy command. | |
73 | * | |
74 | * Use "exec" to avoid "sh -c" processes on some platforms | |
75 | * (e.g. Solaris) | |
76 | */ | |
77 | len = strlen(proxy_command) + 6; | |
78 | tmp = xmalloc(len); | |
79 | strlcpy(tmp, "exec ", len); | |
80 | strlcat(tmp, proxy_command, len); | |
81 | command_string = percent_expand(tmp, "h", host, | |
82 | "p", strport, (char *)NULL); | |
83 | xfree(tmp); | |
3c0ef626 | 84 | |
85 | /* Create pipes for communicating with the proxy. */ | |
86 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
87 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
473db5ab | 88 | strerror(errno)); |
3c0ef626 | 89 | |
90 | debug("Executing proxy command: %.500s", command_string); | |
91 | ||
92 | /* Fork and execute the proxy command. */ | |
93 | if ((pid = fork()) == 0) { | |
94 | char *argv[10]; | |
95 | ||
96 | /* Child. Permanently give up superuser privileges. */ | |
473db5ab | 97 | seteuid(original_real_uid); |
98 | setuid(original_real_uid); | |
3c0ef626 | 99 | |
100 | /* Redirect stdin and stdout. */ | |
101 | close(pin[1]); | |
102 | if (pin[0] != 0) { | |
103 | if (dup2(pin[0], 0) < 0) | |
104 | perror("dup2 stdin"); | |
105 | close(pin[0]); | |
106 | } | |
107 | close(pout[0]); | |
108 | if (dup2(pout[1], 1) < 0) | |
109 | perror("dup2 stdout"); | |
110 | /* Cannot be 1 because pin allocated two descriptors. */ | |
111 | close(pout[1]); | |
112 | ||
113 | /* Stderr is left as it is so that error messages get | |
114 | printed on the user's terminal. */ | |
115 | argv[0] = _PATH_BSHELL; | |
116 | argv[1] = "-c"; | |
117 | argv[2] = command_string; | |
118 | argv[3] = NULL; | |
119 | ||
120 | /* Execute the proxy command. Note that we gave up any | |
121 | extra privileges above. */ | |
122 | execv(argv[0], argv); | |
123 | perror(argv[0]); | |
124 | exit(1); | |
125 | } | |
126 | /* Parent. */ | |
127 | if (pid < 0) | |
128 | fatal("fork failed: %.100s", strerror(errno)); | |
473db5ab | 129 | else |
130 | proxy_command_pid = pid; /* save pid to clean up later */ | |
3c0ef626 | 131 | |
132 | /* Close child side of the descriptors. */ | |
133 | close(pin[0]); | |
134 | close(pout[1]); | |
135 | ||
136 | /* Free the command name. */ | |
473db5ab | 137 | xfree(command_string); |
3c0ef626 | 138 | |
139 | /* Set the connection file descriptors. */ | |
140 | packet_set_connection(pout[0], pin[1]); | |
141 | ||
142 | /* Indicate OK return */ | |
143 | return 0; | |
144 | } | |
145 | ||
a7213e65 | 146 | /* |
147 | * Set TCP receive buffer if requested. | |
148 | * Note: tuning needs to happen after the socket is | |
149 | * created but before the connection happens | |
150 | * so winscale is negotiated properly -cjr | |
151 | */ | |
152 | static void | |
153 | ssh_set_socket_recvbuf(int sock) | |
154 | { | |
155 | void *buf = (void *)&options.tcp_rcv_buf; | |
156 | int sz = sizeof(options.tcp_rcv_buf); | |
157 | int socksize; | |
158 | int socksizelen = sizeof(int); | |
159 | ||
160 | debug("setsockopt Attempting to set SO_RCVBUF to %d", options.tcp_rcv_buf); | |
161 | if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF, buf, sz) >= 0) { | |
162 | getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &socksize, &socksizelen); | |
163 | debug("setsockopt SO_RCVBUF: %.100s %d", strerror(errno), socksize); | |
164 | } | |
165 | else | |
166 | error("Couldn't set socket receive buffer to %d: %.100s", | |
167 | options.tcp_rcv_buf, strerror(errno)); | |
168 | } | |
169 | ||
170 | ||
3c0ef626 | 171 | /* |
172 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
173 | */ | |
174 | static int | |
473db5ab | 175 | ssh_create_socket(int privileged, struct addrinfo *ai) |
3c0ef626 | 176 | { |
177 | int sock, gaierr; | |
178 | struct addrinfo hints, *res; | |
179 | ||
180 | /* | |
181 | * If we are running as root and want to connect to a privileged | |
182 | * port, bind our own socket to a privileged port. | |
183 | */ | |
184 | if (privileged) { | |
185 | int p = IPPORT_RESERVED - 1; | |
473db5ab | 186 | PRIV_START; |
187 | sock = rresvport_af(&p, ai->ai_family); | |
188 | PRIV_END; | |
3c0ef626 | 189 | if (sock < 0) |
473db5ab | 190 | error("rresvport: af=%d %.100s", ai->ai_family, |
191 | strerror(errno)); | |
3c0ef626 | 192 | else |
193 | debug("Allocated local port %d.", p); | |
473db5ab | 194 | |
a7213e65 | 195 | if (options.tcp_rcv_buf > 0) |
196 | ssh_set_socket_recvbuf(sock); | |
3c0ef626 | 197 | return sock; |
198 | } | |
473db5ab | 199 | sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); |
3c0ef626 | 200 | if (sock < 0) |
201 | error("socket: %.100s", strerror(errno)); | |
473db5ab | 202 | |
a7213e65 | 203 | if (options.tcp_rcv_buf > 0) |
204 | ssh_set_socket_recvbuf(sock); | |
473db5ab | 205 | |
206 | /* Bind the socket to an alternative local IP address */ | |
3c0ef626 | 207 | if (options.bind_address == NULL) |
208 | return sock; | |
209 | ||
210 | memset(&hints, 0, sizeof(hints)); | |
473db5ab | 211 | hints.ai_family = ai->ai_family; |
212 | hints.ai_socktype = ai->ai_socktype; | |
213 | hints.ai_protocol = ai->ai_protocol; | |
3c0ef626 | 214 | hints.ai_flags = AI_PASSIVE; |
215 | gaierr = getaddrinfo(options.bind_address, "0", &hints, &res); | |
216 | if (gaierr) { | |
217 | error("getaddrinfo: %s: %s", options.bind_address, | |
218 | gai_strerror(gaierr)); | |
219 | close(sock); | |
220 | return -1; | |
221 | } | |
222 | if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { | |
223 | error("bind: %s: %s", options.bind_address, strerror(errno)); | |
224 | close(sock); | |
225 | freeaddrinfo(res); | |
226 | return -1; | |
227 | } | |
228 | freeaddrinfo(res); | |
229 | return sock; | |
230 | } | |
231 | ||
473db5ab | 232 | static int |
233 | timeout_connect(int sockfd, const struct sockaddr *serv_addr, | |
234 | socklen_t addrlen, int timeout) | |
235 | { | |
236 | fd_set *fdset; | |
237 | struct timeval tv; | |
238 | socklen_t optlen; | |
239 | int fdsetsz, optval, rc, result = -1; | |
240 | ||
241 | if (timeout <= 0) | |
242 | return (connect(sockfd, serv_addr, addrlen)); | |
243 | ||
244 | set_nonblock(sockfd); | |
245 | rc = connect(sockfd, serv_addr, addrlen); | |
246 | if (rc == 0) { | |
247 | unset_nonblock(sockfd); | |
248 | return (0); | |
249 | } | |
250 | if (errno != EINPROGRESS) | |
251 | return (-1); | |
252 | ||
253 | fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask); | |
254 | fdset = (fd_set *)xmalloc(fdsetsz); | |
255 | ||
256 | memset(fdset, 0, fdsetsz); | |
257 | FD_SET(sockfd, fdset); | |
258 | tv.tv_sec = timeout; | |
259 | tv.tv_usec = 0; | |
260 | ||
261 | for (;;) { | |
262 | rc = select(sockfd + 1, NULL, fdset, NULL, &tv); | |
263 | if (rc != -1 || errno != EINTR) | |
264 | break; | |
265 | } | |
266 | ||
267 | switch (rc) { | |
268 | case 0: | |
269 | /* Timed out */ | |
270 | errno = ETIMEDOUT; | |
271 | break; | |
272 | case -1: | |
273 | /* Select error */ | |
274 | debug("select: %s", strerror(errno)); | |
275 | break; | |
276 | case 1: | |
277 | /* Completed or failed */ | |
278 | optval = 0; | |
279 | optlen = sizeof(optval); | |
280 | if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, | |
281 | &optlen) == -1) { | |
282 | debug("getsockopt: %s", strerror(errno)); | |
283 | break; | |
284 | } | |
285 | if (optval != 0) { | |
286 | errno = optval; | |
287 | break; | |
288 | } | |
289 | result = 0; | |
290 | unset_nonblock(sockfd); | |
291 | break; | |
292 | default: | |
293 | /* Should not occur */ | |
294 | fatal("Bogus return (%d) from select()", rc); | |
295 | } | |
296 | ||
297 | xfree(fdset); | |
298 | return (result); | |
299 | } | |
300 | ||
3c0ef626 | 301 | /* |
302 | * Opens a TCP/IP connection to the remote server on the given host. | |
303 | * The address of the remote host will be returned in hostaddr. | |
473db5ab | 304 | * If port is 0, the default port will be used. If needpriv is true, |
3c0ef626 | 305 | * a privileged port will be allocated to make the connection. |
473db5ab | 306 | * This requires super-user privileges if needpriv is true. |
3c0ef626 | 307 | * Connection_attempts specifies the maximum number of tries (one per |
308 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
309 | * and %p substituted for host and port, respectively) to use to contact | |
310 | * the daemon. | |
3c0ef626 | 311 | */ |
312 | int | |
313 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, | |
314 | u_short port, int family, int connection_attempts, | |
473db5ab | 315 | int needpriv, const char *proxy_command) |
3c0ef626 | 316 | { |
317 | int gaierr; | |
318 | int on = 1; | |
319 | int sock = -1, attempt; | |
320 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
321 | struct addrinfo hints, *ai, *aitop; | |
3c0ef626 | 322 | |
473db5ab | 323 | debug2("ssh_connect: needpriv %d", needpriv); |
3c0ef626 | 324 | |
3c0ef626 | 325 | /* If a proxy command is given, connect using it. */ |
326 | if (proxy_command != NULL) | |
473db5ab | 327 | return ssh_proxy_connect(host, port, proxy_command); |
3c0ef626 | 328 | |
329 | /* No proxy command. */ | |
330 | ||
331 | memset(&hints, 0, sizeof(hints)); | |
332 | hints.ai_family = family; | |
333 | hints.ai_socktype = SOCK_STREAM; | |
473db5ab | 334 | snprintf(strport, sizeof strport, "%u", port); |
3c0ef626 | 335 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) |
336 | fatal("%s: %.100s: %s", __progname, host, | |
337 | gai_strerror(gaierr)); | |
338 | ||
339 | /* | |
340 | * Try to connect several times. On some machines, the first time | |
341 | * will sometimes fail. In general socket code appears to behave | |
342 | * quite magically on many machines. | |
343 | */ | |
344 | for (attempt = 0; ;) { | |
345 | if (attempt > 0) | |
346 | debug("Trying again..."); | |
347 | ||
348 | /* Loop through addresses for this host, and try each one in | |
349 | sequence until the connection succeeds. */ | |
350 | for (ai = aitop; ai; ai = ai->ai_next) { | |
351 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
352 | continue; | |
353 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
354 | ntop, sizeof(ntop), strport, sizeof(strport), | |
355 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
356 | error("ssh_connect: getnameinfo failed"); | |
357 | continue; | |
358 | } | |
359 | debug("Connecting to %.200s [%.100s] port %s.", | |
360 | host, ntop, strport); | |
361 | ||
362 | /* Create a socket for connecting. */ | |
473db5ab | 363 | sock = ssh_create_socket(needpriv, ai); |
3c0ef626 | 364 | if (sock < 0) |
365 | /* Any error is already output */ | |
366 | continue; | |
367 | ||
473db5ab | 368 | if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, |
369 | options.connection_timeout) >= 0) { | |
3c0ef626 | 370 | /* Successful connection. */ |
371 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); | |
3c0ef626 | 372 | break; |
373 | } else { | |
473db5ab | 374 | debug("connect to address %s port %s: %s", |
375 | ntop, strport, strerror(errno)); | |
3c0ef626 | 376 | /* |
377 | * Close the failed socket; there appear to | |
378 | * be some problems when reusing a socket for | |
379 | * which connect() has already returned an | |
380 | * error. | |
381 | */ | |
3c0ef626 | 382 | close(sock); |
383 | } | |
384 | } | |
385 | if (ai) | |
386 | break; /* Successful connection. */ | |
387 | ||
388 | attempt++; | |
389 | if (attempt >= connection_attempts) | |
390 | break; | |
391 | /* Sleep a moment before retrying. */ | |
392 | sleep(1); | |
393 | } | |
394 | ||
395 | freeaddrinfo(aitop); | |
396 | ||
397 | /* Return failure if we didn't get a successful connection. */ | |
473db5ab | 398 | if (attempt >= connection_attempts) { |
399 | error("ssh: connect to host %s port %s: %s", | |
400 | host, strport, strerror(errno)); | |
401 | return (-1); | |
402 | } | |
3c0ef626 | 403 | |
404 | debug("Connection established."); | |
405 | ||
473db5ab | 406 | /* Set SO_KEEPALIVE if requested. */ |
407 | if (options.tcp_keep_alive && | |
3c0ef626 | 408 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, |
409 | sizeof(on)) < 0) | |
410 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
411 | ||
412 | /* Set the connection. */ | |
413 | packet_set_connection(sock, sock); | |
414 | ||
415 | return 0; | |
416 | } | |
417 | ||
418 | /* | |
419 | * Waits for the server identification string, and sends our own | |
420 | * identification string. | |
421 | */ | |
422 | static void | |
423 | ssh_exchange_identification(void) | |
424 | { | |
425 | char buf[256], remote_version[256]; /* must be same size! */ | |
473db5ab | 426 | int remote_major, remote_minor, mismatch; |
3c0ef626 | 427 | int connection_in = packet_get_connection_in(); |
428 | int connection_out = packet_get_connection_out(); | |
429 | int minor1 = PROTOCOL_MINOR_1; | |
473db5ab | 430 | u_int i; |
3c0ef626 | 431 | |
473db5ab | 432 | /* Read other side's version identification. */ |
3c0ef626 | 433 | for (;;) { |
434 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
473db5ab | 435 | size_t len = atomicio(read, connection_in, &buf[i], 1); |
436 | ||
437 | if (len != 1 && errno == EPIPE) | |
3c0ef626 | 438 | fatal("ssh_exchange_identification: Connection closed by remote host"); |
473db5ab | 439 | else if (len != 1) |
440 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); | |
3c0ef626 | 441 | if (buf[i] == '\r') { |
442 | buf[i] = '\n'; | |
443 | buf[i + 1] = 0; | |
444 | continue; /**XXX wait for \n */ | |
445 | } | |
446 | if (buf[i] == '\n') { | |
447 | buf[i + 1] = 0; | |
448 | break; | |
449 | } | |
450 | } | |
451 | buf[sizeof(buf) - 1] = 0; | |
452 | if (strncmp(buf, "SSH-", 4) == 0) | |
453 | break; | |
454 | debug("ssh_exchange_identification: %s", buf); | |
455 | } | |
456 | server_version_string = xstrdup(buf); | |
457 | ||
458 | /* | |
459 | * Check that the versions match. In future this might accept | |
460 | * several versions and set appropriate flags to handle them. | |
461 | */ | |
462 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", | |
463 | &remote_major, &remote_minor, remote_version) != 3) | |
464 | fatal("Bad remote protocol version identification: '%.100s'", buf); | |
465 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
473db5ab | 466 | remote_major, remote_minor, remote_version); |
3c0ef626 | 467 | |
468 | compat_datafellows(remote_version); | |
469 | mismatch = 0; | |
470 | ||
473db5ab | 471 | switch (remote_major) { |
3c0ef626 | 472 | case 1: |
473 | if (remote_minor == 99 && | |
474 | (options.protocol & SSH_PROTO_2) && | |
475 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
476 | enable_compat20(); | |
477 | break; | |
478 | } | |
479 | if (!(options.protocol & SSH_PROTO_1)) { | |
480 | mismatch = 1; | |
481 | break; | |
482 | } | |
483 | if (remote_minor < 3) { | |
484 | fatal("Remote machine has too old SSH software version."); | |
485 | } else if (remote_minor == 3 || remote_minor == 4) { | |
486 | /* We speak 1.3, too. */ | |
487 | enable_compat13(); | |
488 | minor1 = 3; | |
489 | if (options.forward_agent) { | |
473db5ab | 490 | logit("Agent forwarding disabled for protocol 1.3"); |
3c0ef626 | 491 | options.forward_agent = 0; |
492 | } | |
493 | } | |
494 | break; | |
495 | case 2: | |
496 | if (options.protocol & SSH_PROTO_2) { | |
497 | enable_compat20(); | |
498 | break; | |
499 | } | |
500 | /* FALLTHROUGH */ | |
501 | default: | |
502 | mismatch = 1; | |
503 | break; | |
504 | } | |
505 | if (mismatch) | |
506 | fatal("Protocol major versions differ: %d vs. %d", | |
507 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, | |
508 | remote_major); | |
509 | /* Send our own protocol version identification. */ | |
510 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
511 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, | |
512 | compat20 ? PROTOCOL_MINOR_2 : minor1, | |
473db5ab | 513 | SSH_RELEASE); |
514 | if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf)) | |
3c0ef626 | 515 | fatal("write: %.100s", strerror(errno)); |
516 | client_version_string = xstrdup(buf); | |
517 | chop(client_version_string); | |
518 | chop(server_version_string); | |
519 | debug("Local version string %.100s", client_version_string); | |
520 | } | |
521 | ||
522 | /* defaults to 'no' */ | |
523 | static int | |
524 | confirm(const char *prompt) | |
525 | { | |
473db5ab | 526 | const char *msg, *again = "Please type 'yes' or 'no': "; |
527 | char *p; | |
528 | int ret = -1; | |
3c0ef626 | 529 | |
530 | if (options.batch_mode) | |
531 | return 0; | |
473db5ab | 532 | for (msg = prompt;;msg = again) { |
533 | p = read_passphrase(msg, RP_ECHO); | |
534 | if (p == NULL || | |
535 | (p[0] == '\0') || (p[0] == '\n') || | |
536 | strncasecmp(p, "no", 2) == 0) | |
537 | ret = 0; | |
538 | if (p && strncasecmp(p, "yes", 3) == 0) | |
539 | ret = 1; | |
540 | if (p) | |
541 | xfree(p); | |
542 | if (ret != -1) | |
543 | return ret; | |
3c0ef626 | 544 | } |
545 | } | |
546 | ||
547 | /* | |
548 | * check whether the supplied host key is valid, return -1 if the key | |
549 | * is not valid. the user_hostfile will not be updated if 'readonly' is true. | |
550 | */ | |
3c0ef626 | 551 | static int |
552 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, | |
553 | int readonly, const char *user_hostfile, const char *system_hostfile) | |
554 | { | |
555 | Key *file_key; | |
473db5ab | 556 | const char *type = key_type(host_key); |
3c0ef626 | 557 | char *ip = NULL; |
558 | char hostline[1000], *hostp, *fp; | |
559 | HostStatus host_status; | |
560 | HostStatus ip_status; | |
473db5ab | 561 | int r, local = 0, host_ip_differ = 0; |
3c0ef626 | 562 | int salen; |
563 | char ntop[NI_MAXHOST]; | |
473db5ab | 564 | char msg[1024]; |
565 | int len, host_line, ip_line; | |
3c0ef626 | 566 | const char *host_file = NULL, *ip_file = NULL; |
567 | ||
568 | /* | |
569 | * Force accepting of the host key for loopback/localhost. The | |
570 | * problem is that if the home directory is NFS-mounted to multiple | |
571 | * machines, localhost will refer to a different machine in each of | |
572 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
573 | * essentially disables host authentication for localhost; however, | |
574 | * this is probably not a real problem. | |
575 | */ | |
576 | /** hostaddr == 0! */ | |
577 | switch (hostaddr->sa_family) { | |
578 | case AF_INET: | |
579 | local = (ntohl(((struct sockaddr_in *)hostaddr)-> | |
580 | sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; | |
581 | salen = sizeof(struct sockaddr_in); | |
582 | break; | |
583 | case AF_INET6: | |
584 | local = IN6_IS_ADDR_LOOPBACK( | |
585 | &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
586 | salen = sizeof(struct sockaddr_in6); | |
587 | break; | |
588 | default: | |
589 | local = 0; | |
590 | salen = sizeof(struct sockaddr_storage); | |
591 | break; | |
592 | } | |
593 | if (options.no_host_authentication_for_localhost == 1 && local && | |
594 | options.host_key_alias == NULL) { | |
595 | debug("Forcing accepting of host key for " | |
596 | "loopback/localhost."); | |
597 | return 0; | |
598 | } | |
599 | ||
600 | /* | |
601 | * We don't have the remote ip-address for connections | |
602 | * using a proxy command | |
603 | */ | |
604 | if (options.proxy_command == NULL) { | |
605 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), | |
606 | NULL, 0, NI_NUMERICHOST) != 0) | |
607 | fatal("check_host_key: getnameinfo failed"); | |
608 | ip = xstrdup(ntop); | |
609 | } else { | |
610 | ip = xstrdup("<no hostip for proxy command>"); | |
611 | } | |
612 | /* | |
613 | * Turn off check_host_ip if the connection is to localhost, via proxy | |
614 | * command or if we don't have a hostname to compare with | |
615 | */ | |
616 | if (options.check_host_ip && | |
617 | (local || strcmp(host, ip) == 0 || options.proxy_command != NULL)) | |
618 | options.check_host_ip = 0; | |
619 | ||
620 | /* | |
621 | * Allow the user to record the key under a different name. This is | |
622 | * useful for ssh tunneling over forwarded connections or if you run | |
623 | * multiple sshd's on different ports on the same machine. | |
624 | */ | |
625 | if (options.host_key_alias != NULL) { | |
626 | host = options.host_key_alias; | |
627 | debug("using hostkeyalias: %s", host); | |
628 | } | |
629 | ||
630 | /* | |
631 | * Store the host key from the known host file in here so that we can | |
632 | * compare it with the key for the IP address. | |
633 | */ | |
634 | file_key = key_new(host_key->type); | |
635 | ||
636 | /* | |
08822d99 | 637 | * Check if the host key is present in the user's list of known |
3c0ef626 | 638 | * hosts or in the systemwide list. |
639 | */ | |
640 | host_file = user_hostfile; | |
641 | host_status = check_host_in_hostfile(host_file, host, host_key, | |
473db5ab | 642 | file_key, &host_line); |
3c0ef626 | 643 | if (host_status == HOST_NEW) { |
644 | host_file = system_hostfile; | |
645 | host_status = check_host_in_hostfile(host_file, host, host_key, | |
646 | file_key, &host_line); | |
647 | } | |
648 | /* | |
649 | * Also perform check for the ip address, skip the check if we are | |
650 | * localhost or the hostname was an ip address to begin with | |
651 | */ | |
652 | if (options.check_host_ip) { | |
653 | Key *ip_key = key_new(host_key->type); | |
654 | ||
655 | ip_file = user_hostfile; | |
656 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, | |
657 | ip_key, &ip_line); | |
658 | if (ip_status == HOST_NEW) { | |
659 | ip_file = system_hostfile; | |
660 | ip_status = check_host_in_hostfile(ip_file, ip, | |
661 | host_key, ip_key, &ip_line); | |
662 | } | |
663 | if (host_status == HOST_CHANGED && | |
664 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) | |
665 | host_ip_differ = 1; | |
666 | ||
667 | key_free(ip_key); | |
668 | } else | |
669 | ip_status = host_status; | |
670 | ||
671 | key_free(file_key); | |
672 | ||
673 | switch (host_status) { | |
674 | case HOST_OK: | |
675 | /* The host is known and the key matches. */ | |
676 | debug("Host '%.200s' is known and matches the %s host key.", | |
677 | host, type); | |
678 | debug("Found key in %s:%d", host_file, host_line); | |
679 | if (options.check_host_ip && ip_status == HOST_NEW) { | |
680 | if (readonly) | |
473db5ab | 681 | logit("%s host key for IP address " |
3c0ef626 | 682 | "'%.128s' not in list of known hosts.", |
683 | type, ip); | |
684 | else if (!add_host_to_hostfile(user_hostfile, ip, | |
473db5ab | 685 | host_key, options.hash_known_hosts)) |
686 | logit("Failed to add the %s host key for IP " | |
3c0ef626 | 687 | "address '%.128s' to the list of known " |
688 | "hosts (%.30s).", type, ip, user_hostfile); | |
689 | else | |
473db5ab | 690 | logit("Warning: Permanently added the %s host " |
3c0ef626 | 691 | "key for IP address '%.128s' to the list " |
692 | "of known hosts.", type, ip); | |
693 | } | |
694 | break; | |
695 | case HOST_NEW: | |
696 | if (readonly) | |
697 | goto fail; | |
698 | /* The host is new. */ | |
699 | if (options.strict_host_key_checking == 1) { | |
700 | /* | |
701 | * User has requested strict host key checking. We | |
702 | * will not add the host key automatically. The only | |
703 | * alternative left is to abort. | |
704 | */ | |
705 | error("No %s host key is known for %.200s and you " | |
706 | "have requested strict checking.", type, host); | |
707 | goto fail; | |
708 | } else if (options.strict_host_key_checking == 2) { | |
473db5ab | 709 | char msg1[1024], msg2[1024]; |
710 | ||
711 | if (show_other_keys(host, host_key)) | |
712 | snprintf(msg1, sizeof(msg1), | |
713 | "\nbut keys of different type are already" | |
714 | " known for this host."); | |
715 | else | |
716 | snprintf(msg1, sizeof(msg1), "."); | |
3c0ef626 | 717 | /* The default */ |
3c0ef626 | 718 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
473db5ab | 719 | msg2[0] = '\0'; |
720 | if (options.verify_host_key_dns) { | |
721 | if (matching_host_key_dns) | |
722 | snprintf(msg2, sizeof(msg2), | |
723 | "Matching host key fingerprint" | |
724 | " found in DNS.\n"); | |
725 | else | |
726 | snprintf(msg2, sizeof(msg2), | |
727 | "No matching host key fingerprint" | |
728 | " found in DNS.\n"); | |
729 | } | |
730 | snprintf(msg, sizeof(msg), | |
3c0ef626 | 731 | "The authenticity of host '%.200s (%s)' can't be " |
473db5ab | 732 | "established%s\n" |
733 | "%s key fingerprint is %s.\n%s" | |
3c0ef626 | 734 | "Are you sure you want to continue connecting " |
473db5ab | 735 | "(yes/no)? ", |
736 | host, ip, msg1, type, fp, msg2); | |
3c0ef626 | 737 | xfree(fp); |
473db5ab | 738 | if (!confirm(msg)) |
3c0ef626 | 739 | goto fail; |
3c0ef626 | 740 | } |
3c0ef626 | 741 | /* |
742 | * If not in strict mode, add the key automatically to the | |
743 | * local known_hosts file. | |
744 | */ | |
473db5ab | 745 | if (options.check_host_ip && ip_status == HOST_NEW) { |
746 | snprintf(hostline, sizeof(hostline), "%s,%s", | |
747 | host, ip); | |
748 | hostp = hostline; | |
749 | if (options.hash_known_hosts) { | |
750 | /* Add hash of host and IP separately */ | |
751 | r = add_host_to_hostfile(user_hostfile, host, | |
752 | host_key, options.hash_known_hosts) && | |
753 | add_host_to_hostfile(user_hostfile, ip, | |
754 | host_key, options.hash_known_hosts); | |
755 | } else { | |
756 | /* Add unhashed "host,ip" */ | |
757 | r = add_host_to_hostfile(user_hostfile, | |
758 | hostline, host_key, | |
759 | options.hash_known_hosts); | |
760 | } | |
761 | } else { | |
762 | r = add_host_to_hostfile(user_hostfile, host, host_key, | |
763 | options.hash_known_hosts); | |
764 | hostp = host; | |
765 | } | |
766 | ||
767 | if (!r) | |
768 | logit("Failed to add the host to the list of known " | |
3c0ef626 | 769 | "hosts (%.500s).", user_hostfile); |
770 | else | |
473db5ab | 771 | logit("Warning: Permanently added '%.200s' (%s) to the " |
3c0ef626 | 772 | "list of known hosts.", hostp, type); |
773 | break; | |
774 | case HOST_CHANGED: | |
775 | if (options.check_host_ip && host_ip_differ) { | |
473db5ab | 776 | char *key_msg; |
3c0ef626 | 777 | if (ip_status == HOST_NEW) |
473db5ab | 778 | key_msg = "is unknown"; |
3c0ef626 | 779 | else if (ip_status == HOST_OK) |
473db5ab | 780 | key_msg = "is unchanged"; |
3c0ef626 | 781 | else |
473db5ab | 782 | key_msg = "has a different value"; |
3c0ef626 | 783 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
784 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
785 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
786 | error("The %s host key for %s has changed,", type, host); | |
787 | error("and the key for the according IP address %s", ip); | |
473db5ab | 788 | error("%s. This could either mean that", key_msg); |
3c0ef626 | 789 | error("DNS SPOOFING is happening or the IP address for the host"); |
790 | error("and its host key have changed at the same time."); | |
791 | if (ip_status != HOST_NEW) | |
792 | error("Offending key for IP in %s:%d", ip_file, ip_line); | |
793 | } | |
794 | /* The host key has changed. */ | |
473db5ab | 795 | warn_changed_key(host_key); |
3c0ef626 | 796 | error("Add correct host key in %.100s to get rid of this message.", |
797 | user_hostfile); | |
798 | error("Offending key in %s:%d", host_file, host_line); | |
3c0ef626 | 799 | |
800 | /* | |
801 | * If strict host key checking is in use, the user will have | |
802 | * to edit the key manually and we can only abort. | |
803 | */ | |
804 | if (options.strict_host_key_checking) { | |
805 | error("%s host key for %.200s has changed and you have " | |
806 | "requested strict checking.", type, host); | |
807 | goto fail; | |
808 | } | |
809 | ||
810 | /* | |
811 | * If strict host key checking has not been requested, allow | |
473db5ab | 812 | * the connection but without MITM-able authentication or |
3c0ef626 | 813 | * agent forwarding. |
814 | */ | |
815 | if (options.password_authentication) { | |
816 | error("Password authentication is disabled to avoid " | |
817 | "man-in-the-middle attacks."); | |
818 | options.password_authentication = 0; | |
819 | } | |
473db5ab | 820 | if (options.kbd_interactive_authentication) { |
821 | error("Keyboard-interactive authentication is disabled" | |
822 | " to avoid man-in-the-middle attacks."); | |
823 | options.kbd_interactive_authentication = 0; | |
824 | options.challenge_response_authentication = 0; | |
825 | } | |
826 | if (options.challenge_response_authentication) { | |
827 | error("Challenge/response authentication is disabled" | |
828 | " to avoid man-in-the-middle attacks."); | |
829 | options.challenge_response_authentication = 0; | |
830 | } | |
3c0ef626 | 831 | if (options.forward_agent) { |
832 | error("Agent forwarding is disabled to avoid " | |
833 | "man-in-the-middle attacks."); | |
834 | options.forward_agent = 0; | |
835 | } | |
836 | if (options.forward_x11) { | |
837 | error("X11 forwarding is disabled to avoid " | |
838 | "man-in-the-middle attacks."); | |
839 | options.forward_x11 = 0; | |
840 | } | |
841 | if (options.num_local_forwards > 0 || | |
842 | options.num_remote_forwards > 0) { | |
843 | error("Port forwarding is disabled to avoid " | |
844 | "man-in-the-middle attacks."); | |
845 | options.num_local_forwards = | |
473db5ab | 846 | options.num_remote_forwards = 0; |
3c0ef626 | 847 | } |
848 | /* | |
849 | * XXX Should permit the user to change to use the new id. | |
850 | * This could be done by converting the host key to an | |
851 | * identifying sentence, tell that the host identifies itself | |
852 | * by that sentence, and ask the user if he/she whishes to | |
853 | * accept the authentication. | |
854 | */ | |
855 | break; | |
473db5ab | 856 | case HOST_FOUND: |
857 | fatal("internal error"); | |
858 | break; | |
3c0ef626 | 859 | } |
860 | ||
861 | if (options.check_host_ip && host_status != HOST_CHANGED && | |
862 | ip_status == HOST_CHANGED) { | |
473db5ab | 863 | snprintf(msg, sizeof(msg), |
864 | "Warning: the %s host key for '%.200s' " | |
865 | "differs from the key for the IP address '%.128s'" | |
866 | "\nOffending key for IP in %s:%d", | |
867 | type, host, ip, ip_file, ip_line); | |
868 | if (host_status == HOST_OK) { | |
869 | len = strlen(msg); | |
870 | snprintf(msg + len, sizeof(msg) - len, | |
871 | "\nMatching host key in %s:%d", | |
872 | host_file, host_line); | |
873 | } | |
3c0ef626 | 874 | if (options.strict_host_key_checking == 1) { |
473db5ab | 875 | logit("%s", msg); |
3c0ef626 | 876 | error("Exiting, you have requested strict checking."); |
877 | goto fail; | |
878 | } else if (options.strict_host_key_checking == 2) { | |
473db5ab | 879 | strlcat(msg, "\nAre you sure you want " |
880 | "to continue connecting (yes/no)? ", sizeof(msg)); | |
881 | if (!confirm(msg)) | |
3c0ef626 | 882 | goto fail; |
473db5ab | 883 | } else { |
884 | logit("%s", msg); | |
3c0ef626 | 885 | } |
886 | } | |
887 | ||
888 | xfree(ip); | |
889 | return 0; | |
890 | ||
891 | fail: | |
892 | xfree(ip); | |
893 | return -1; | |
894 | } | |
895 | ||
473db5ab | 896 | /* returns 0 if key verifies or -1 if key does NOT verify */ |
3c0ef626 | 897 | int |
898 | verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) | |
899 | { | |
900 | struct stat st; | |
473db5ab | 901 | int flags = 0; |
902 | ||
903 | if (options.verify_host_key_dns && | |
904 | verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) { | |
905 | ||
906 | if (flags & DNS_VERIFY_FOUND) { | |
907 | ||
908 | if (options.verify_host_key_dns == 1 && | |
909 | flags & DNS_VERIFY_MATCH && | |
910 | flags & DNS_VERIFY_SECURE) | |
911 | return 0; | |
912 | ||
913 | if (flags & DNS_VERIFY_MATCH) { | |
914 | matching_host_key_dns = 1; | |
915 | } else { | |
916 | warn_changed_key(host_key); | |
917 | error("Update the SSHFP RR in DNS with the new " | |
918 | "host key to get rid of this message."); | |
919 | } | |
920 | } | |
921 | } | |
3c0ef626 | 922 | |
923 | /* return ok if the key can be found in an old keyfile */ | |
924 | if (stat(options.system_hostfile2, &st) == 0 || | |
925 | stat(options.user_hostfile2, &st) == 0) { | |
926 | if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1, | |
927 | options.user_hostfile2, options.system_hostfile2) == 0) | |
928 | return 0; | |
929 | } | |
930 | return check_host_key(host, hostaddr, host_key, /*readonly*/ 0, | |
931 | options.user_hostfile, options.system_hostfile); | |
932 | } | |
933 | ||
934 | /* | |
935 | * Starts a dialog with the server, and authenticates the current user on the | |
936 | * server. This does not need any extra privileges. The basic connection | |
937 | * to the server must already have been established before this is called. | |
938 | * If login fails, this function prints an error and never returns. | |
939 | * This function does not require super-user privileges. | |
940 | */ | |
941 | void | |
473db5ab | 942 | ssh_login(Sensitive *sensitive, const char *orighost, |
3c0ef626 | 943 | struct sockaddr *hostaddr, struct passwd *pw) |
944 | { | |
945 | char *host, *cp; | |
946 | char *server_user, *local_user; | |
947 | ||
948 | local_user = xstrdup(pw->pw_name); | |
949 | server_user = options.user ? options.user : local_user; | |
950 | ||
951 | /* Convert the user-supplied hostname into all lowercase. */ | |
952 | host = xstrdup(orighost); | |
953 | for (cp = host; *cp; cp++) | |
954 | if (isupper(*cp)) | |
955 | *cp = tolower(*cp); | |
956 | ||
957 | /* Exchange protocol version identification strings with the server. */ | |
958 | ssh_exchange_identification(); | |
959 | ||
960 | /* Put the connection into non-blocking mode. */ | |
961 | packet_set_nonblocking(); | |
962 | ||
963 | /* key exchange */ | |
964 | /* authenticate user */ | |
965 | if (compat20) { | |
966 | ssh_kex2(host, hostaddr); | |
473db5ab | 967 | ssh_userauth2(local_user, server_user, host, sensitive); |
3c0ef626 | 968 | } else { |
969 | ssh_kex(host, hostaddr); | |
473db5ab | 970 | ssh_userauth1(local_user, server_user, host, sensitive); |
3c0ef626 | 971 | } |
972 | } | |
973 | ||
974 | void | |
975 | ssh_put_password(char *password) | |
976 | { | |
977 | int size; | |
978 | char *padded; | |
979 | ||
980 | if (datafellows & SSH_BUG_PASSWORDPAD) { | |
981 | packet_put_cstring(password); | |
982 | return; | |
983 | } | |
984 | size = roundup(strlen(password) + 1, 32); | |
985 | padded = xmalloc(size); | |
986 | memset(padded, 0, size); | |
987 | strlcpy(padded, password, size); | |
988 | packet_put_string(padded, size); | |
989 | memset(padded, 0, size); | |
990 | xfree(padded); | |
991 | } | |
473db5ab | 992 | |
993 | static int | |
994 | show_key_from_file(const char *file, const char *host, int keytype) | |
995 | { | |
996 | Key *found; | |
997 | char *fp; | |
998 | int line, ret; | |
999 | ||
1000 | found = key_new(keytype); | |
1001 | if ((ret = lookup_key_in_hostfile_by_type(file, host, | |
1002 | keytype, found, &line))) { | |
1003 | fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX); | |
1004 | logit("WARNING: %s key found for host %s\n" | |
1005 | "in %s:%d\n" | |
1006 | "%s key fingerprint %s.", | |
1007 | key_type(found), host, file, line, | |
1008 | key_type(found), fp); | |
1009 | xfree(fp); | |
1010 | } | |
1011 | key_free(found); | |
1012 | return (ret); | |
1013 | } | |
1014 | ||
1015 | /* print all known host keys for a given host, but skip keys of given type */ | |
1016 | static int | |
1017 | show_other_keys(const char *host, Key *key) | |
1018 | { | |
1019 | int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1}; | |
1020 | int i, found = 0; | |
1021 | ||
1022 | for (i = 0; type[i] != -1; i++) { | |
1023 | if (type[i] == key->type) | |
1024 | continue; | |
1025 | if (type[i] != KEY_RSA1 && | |
1026 | show_key_from_file(options.user_hostfile2, host, type[i])) { | |
1027 | found = 1; | |
1028 | continue; | |
1029 | } | |
1030 | if (type[i] != KEY_RSA1 && | |
1031 | show_key_from_file(options.system_hostfile2, host, type[i])) { | |
1032 | found = 1; | |
1033 | continue; | |
1034 | } | |
1035 | if (show_key_from_file(options.user_hostfile, host, type[i])) { | |
1036 | found = 1; | |
1037 | continue; | |
1038 | } | |
1039 | if (show_key_from_file(options.system_hostfile, host, type[i])) { | |
1040 | found = 1; | |
1041 | continue; | |
1042 | } | |
1043 | debug2("no key of type %d for host %s", type[i], host); | |
1044 | } | |
1045 | return (found); | |
1046 | } | |
1047 | ||
1048 | static void | |
1049 | warn_changed_key(Key *host_key) | |
1050 | { | |
1051 | char *fp; | |
1052 | const char *type = key_type(host_key); | |
1053 | ||
1054 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); | |
1055 | ||
1056 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1057 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); | |
1058 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1059 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
1060 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
1061 | error("It is also possible that the %s host key has just been changed.", type); | |
1062 | error("The fingerprint for the %s key sent by the remote host is\n%s.", | |
1063 | type, fp); | |
1064 | error("Please contact your system administrator."); | |
1065 | ||
1066 | xfree(fp); | |
1067 | } | |
08822d99 | 1068 | |
1069 | /* | |
1070 | * Execute a local command | |
1071 | */ | |
1072 | int | |
1073 | ssh_local_cmd(const char *args) | |
1074 | { | |
1075 | char *shell; | |
1076 | pid_t pid; | |
1077 | int status; | |
1078 | ||
1079 | if (!options.permit_local_command || | |
1080 | args == NULL || !*args) | |
1081 | return (1); | |
1082 | ||
1083 | if ((shell = getenv("SHELL")) == NULL) | |
1084 | shell = _PATH_BSHELL; | |
1085 | ||
1086 | pid = fork(); | |
1087 | if (pid == 0) { | |
1088 | debug3("Executing %s -c \"%s\"", shell, args); | |
1089 | execl(shell, shell, "-c", args, (char *)NULL); | |
1090 | error("Couldn't execute %s -c \"%s\": %s", | |
1091 | shell, args, strerror(errno)); | |
1092 | _exit(1); | |
1093 | } else if (pid == -1) | |
1094 | fatal("fork failed: %.100s", strerror(errno)); | |
1095 | while (waitpid(pid, &status, 0) == -1) | |
1096 | if (errno != EINTR) | |
1097 | fatal("Couldn't wait for child: %s", strerror(errno)); | |
1098 | ||
1099 | if (!WIFEXITED(status)) | |
1100 | return (1); | |
1101 | ||
1102 | return (WEXITSTATUS(status)); | |
1103 | } |