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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" | |
16 | RCSID("$OpenBSD: sshconnect.c,v 1.131 2002/07/12 13:29:09 itojun Exp $"); | |
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" | |
34 | #include "readpass.h" | |
35 | ||
36 | char *client_version_string = NULL; | |
37 | char *server_version_string = NULL; | |
38 | ||
39 | /* import */ | |
40 | extern Options options; | |
41 | extern char *__progname; | |
42 | extern uid_t original_real_uid; | |
43 | extern uid_t original_effective_uid; | |
44 | ||
45 | #ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */ | |
46 | #define INET6_ADDRSTRLEN 46 | |
47 | #endif | |
48 | ||
49 | /* | |
50 | * Connect to the given ssh server using a proxy command. | |
51 | */ | |
52 | static int | |
53 | ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) | |
54 | { | |
55 | Buffer command; | |
56 | const char *cp; | |
57 | char *command_string; | |
58 | int pin[2], pout[2]; | |
59 | pid_t pid; | |
60 | char strport[NI_MAXSERV]; | |
61 | ||
62 | /* Convert the port number into a string. */ | |
63 | snprintf(strport, sizeof strport, "%hu", port); | |
64 | ||
65 | /* Build the final command string in the buffer by making the | |
66 | appropriate substitutions to the given proxy command. */ | |
67 | buffer_init(&command); | |
68 | for (cp = proxy_command; *cp; cp++) { | |
69 | if (cp[0] == '%' && cp[1] == '%') { | |
70 | buffer_append(&command, "%", 1); | |
71 | cp++; | |
72 | continue; | |
73 | } | |
74 | if (cp[0] == '%' && cp[1] == 'h') { | |
75 | buffer_append(&command, host, strlen(host)); | |
76 | cp++; | |
77 | continue; | |
78 | } | |
79 | if (cp[0] == '%' && cp[1] == 'p') { | |
80 | buffer_append(&command, strport, strlen(strport)); | |
81 | cp++; | |
82 | continue; | |
83 | } | |
84 | buffer_append(&command, cp, 1); | |
85 | } | |
86 | buffer_append(&command, "\0", 1); | |
87 | ||
88 | /* Get the final command string. */ | |
89 | command_string = buffer_ptr(&command); | |
90 | ||
91 | /* Create pipes for communicating with the proxy. */ | |
92 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
93 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
94 | strerror(errno)); | |
95 | ||
96 | debug("Executing proxy command: %.500s", command_string); | |
97 | ||
98 | /* Fork and execute the proxy command. */ | |
99 | if ((pid = fork()) == 0) { | |
100 | char *argv[10]; | |
101 | ||
102 | /* Child. Permanently give up superuser privileges. */ | |
103 | seteuid(original_real_uid); | |
104 | setuid(original_real_uid); | |
105 | ||
106 | /* Redirect stdin and stdout. */ | |
107 | close(pin[1]); | |
108 | if (pin[0] != 0) { | |
109 | if (dup2(pin[0], 0) < 0) | |
110 | perror("dup2 stdin"); | |
111 | close(pin[0]); | |
112 | } | |
113 | close(pout[0]); | |
114 | if (dup2(pout[1], 1) < 0) | |
115 | perror("dup2 stdout"); | |
116 | /* Cannot be 1 because pin allocated two descriptors. */ | |
117 | close(pout[1]); | |
118 | ||
119 | /* Stderr is left as it is so that error messages get | |
120 | printed on the user's terminal. */ | |
121 | argv[0] = _PATH_BSHELL; | |
122 | argv[1] = "-c"; | |
123 | argv[2] = command_string; | |
124 | argv[3] = NULL; | |
125 | ||
126 | /* Execute the proxy command. Note that we gave up any | |
127 | extra privileges above. */ | |
128 | execv(argv[0], argv); | |
129 | perror(argv[0]); | |
130 | exit(1); | |
131 | } | |
132 | /* Parent. */ | |
133 | if (pid < 0) | |
134 | fatal("fork failed: %.100s", strerror(errno)); | |
135 | ||
136 | /* Close child side of the descriptors. */ | |
137 | close(pin[0]); | |
138 | close(pout[1]); | |
139 | ||
140 | /* Free the command name. */ | |
141 | buffer_free(&command); | |
142 | ||
143 | /* Set the connection file descriptors. */ | |
144 | packet_set_connection(pout[0], pin[1]); | |
145 | ||
146 | /* Indicate OK return */ | |
147 | return 0; | |
148 | } | |
149 | ||
150 | /* | |
151 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
152 | */ | |
153 | static int | |
154 | ssh_create_socket(int privileged, int family) | |
155 | { | |
156 | int sock, gaierr; | |
157 | struct addrinfo hints, *res; | |
158 | ||
159 | /* | |
160 | * If we are running as root and want to connect to a privileged | |
161 | * port, bind our own socket to a privileged port. | |
162 | */ | |
163 | if (privileged) { | |
164 | int p = IPPORT_RESERVED - 1; | |
165 | PRIV_START; | |
166 | sock = rresvport_af(&p, family); | |
167 | PRIV_END; | |
168 | if (sock < 0) | |
169 | error("rresvport: af=%d %.100s", family, strerror(errno)); | |
170 | else | |
171 | debug("Allocated local port %d.", p); | |
172 | return sock; | |
173 | } | |
174 | sock = socket(family, SOCK_STREAM, 0); | |
175 | if (sock < 0) | |
176 | error("socket: %.100s", strerror(errno)); | |
177 | ||
178 | /* Bind the socket to an alternative local IP address */ | |
179 | if (options.bind_address == NULL) | |
180 | return sock; | |
181 | ||
182 | memset(&hints, 0, sizeof(hints)); | |
183 | hints.ai_family = family; | |
184 | hints.ai_socktype = SOCK_STREAM; | |
185 | hints.ai_flags = AI_PASSIVE; | |
186 | gaierr = getaddrinfo(options.bind_address, "0", &hints, &res); | |
187 | if (gaierr) { | |
188 | error("getaddrinfo: %s: %s", options.bind_address, | |
189 | gai_strerror(gaierr)); | |
190 | close(sock); | |
191 | return -1; | |
192 | } | |
193 | if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { | |
194 | error("bind: %s: %s", options.bind_address, strerror(errno)); | |
195 | close(sock); | |
196 | freeaddrinfo(res); | |
197 | return -1; | |
198 | } | |
199 | freeaddrinfo(res); | |
200 | return sock; | |
201 | } | |
202 | ||
203 | /* | |
204 | * Opens a TCP/IP connection to the remote server on the given host. | |
205 | * The address of the remote host will be returned in hostaddr. | |
206 | * If port is 0, the default port will be used. If needpriv is true, | |
207 | * a privileged port will be allocated to make the connection. | |
208 | * This requires super-user privileges if needpriv is true. | |
209 | * Connection_attempts specifies the maximum number of tries (one per | |
210 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
211 | * and %p substituted for host and port, respectively) to use to contact | |
212 | * the daemon. | |
213 | * Return values: | |
214 | * 0 for OK | |
215 | * ECONNREFUSED if we got a "Connection Refused" by the peer on any address | |
216 | * ECONNABORTED if we failed without a "Connection refused" | |
217 | * Suitable error messages for the connection failure will already have been | |
218 | * printed. | |
219 | */ | |
220 | int | |
221 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, | |
222 | u_short port, int family, int connection_attempts, | |
223 | int needpriv, const char *proxy_command) | |
224 | { | |
225 | int gaierr; | |
226 | int on = 1; | |
227 | int sock = -1, attempt; | |
228 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
229 | struct addrinfo hints, *ai, *aitop; | |
230 | struct linger linger; | |
231 | struct servent *sp; | |
232 | /* | |
233 | * Did we get only other errors than "Connection refused" (which | |
234 | * should block fallback to rsh and similar), or did we get at least | |
235 | * one "Connection refused"? | |
236 | */ | |
237 | int full_failure = 1; | |
238 | ||
239 | debug("ssh_connect: needpriv %d", needpriv); | |
240 | ||
241 | /* Get default port if port has not been set. */ | |
242 | if (port == 0) { | |
243 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
244 | if (sp) | |
245 | port = ntohs(sp->s_port); | |
246 | else | |
247 | port = SSH_DEFAULT_PORT; | |
248 | } | |
249 | /* If a proxy command is given, connect using it. */ | |
250 | if (proxy_command != NULL) | |
251 | return ssh_proxy_connect(host, port, proxy_command); | |
252 | ||
253 | /* No proxy command. */ | |
254 | ||
255 | memset(&hints, 0, sizeof(hints)); | |
256 | hints.ai_family = family; | |
257 | hints.ai_socktype = SOCK_STREAM; | |
258 | snprintf(strport, sizeof strport, "%u", port); | |
259 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) | |
260 | fatal("%s: %.100s: %s", __progname, host, | |
261 | gai_strerror(gaierr)); | |
262 | ||
263 | /* | |
264 | * Try to connect several times. On some machines, the first time | |
265 | * will sometimes fail. In general socket code appears to behave | |
266 | * quite magically on many machines. | |
267 | */ | |
268 | for (attempt = 0; ;) { | |
269 | if (attempt > 0) | |
270 | debug("Trying again..."); | |
271 | ||
272 | /* Loop through addresses for this host, and try each one in | |
273 | sequence until the connection succeeds. */ | |
274 | for (ai = aitop; ai; ai = ai->ai_next) { | |
275 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
276 | continue; | |
277 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
278 | ntop, sizeof(ntop), strport, sizeof(strport), | |
279 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
280 | error("ssh_connect: getnameinfo failed"); | |
281 | continue; | |
282 | } | |
283 | debug("Connecting to %.200s [%.100s] port %s.", | |
284 | host, ntop, strport); | |
285 | ||
286 | /* Create a socket for connecting. */ | |
287 | sock = ssh_create_socket(needpriv, ai->ai_family); | |
288 | if (sock < 0) | |
289 | /* Any error is already output */ | |
290 | continue; | |
291 | ||
292 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { | |
293 | /* Successful connection. */ | |
294 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); | |
295 | break; | |
296 | } else { | |
297 | if (errno == ECONNREFUSED) | |
298 | full_failure = 0; | |
299 | debug("connect to address %s port %s: %s", | |
300 | ntop, strport, strerror(errno)); | |
301 | /* | |
302 | * Close the failed socket; there appear to | |
303 | * be some problems when reusing a socket for | |
304 | * which connect() has already returned an | |
305 | * error. | |
306 | */ | |
307 | close(sock); | |
308 | } | |
309 | } | |
310 | if (ai) | |
311 | break; /* Successful connection. */ | |
312 | ||
313 | attempt++; | |
314 | if (attempt >= connection_attempts) | |
315 | break; | |
316 | /* Sleep a moment before retrying. */ | |
317 | sleep(1); | |
318 | } | |
319 | ||
320 | freeaddrinfo(aitop); | |
321 | ||
322 | /* Return failure if we didn't get a successful connection. */ | |
323 | if (attempt >= connection_attempts) { | |
324 | log("ssh: connect to host %s port %s: %s", | |
325 | host, strport, strerror(errno)); | |
326 | return full_failure ? ECONNABORTED : ECONNREFUSED; | |
327 | } | |
328 | ||
329 | debug("Connection established."); | |
330 | ||
331 | /* | |
332 | * Set socket options. We would like the socket to disappear as soon | |
333 | * as it has been closed for whatever reason. | |
334 | */ | |
335 | /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
336 | linger.l_onoff = 1; | |
337 | linger.l_linger = 5; | |
338 | setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger)); | |
339 | ||
340 | /* Set keepalives if requested. */ | |
341 | if (options.keepalives && | |
342 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, | |
343 | sizeof(on)) < 0) | |
344 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
345 | ||
346 | /* Set the connection. */ | |
347 | packet_set_connection(sock, sock); | |
348 | ||
349 | return 0; | |
350 | } | |
351 | ||
352 | /* | |
353 | * Waits for the server identification string, and sends our own | |
354 | * identification string. | |
355 | */ | |
356 | static void | |
357 | ssh_exchange_identification(void) | |
358 | { | |
359 | char buf[256], remote_version[256]; /* must be same size! */ | |
360 | int remote_major, remote_minor, i, mismatch; | |
361 | int connection_in = packet_get_connection_in(); | |
362 | int connection_out = packet_get_connection_out(); | |
363 | int minor1 = PROTOCOL_MINOR_1; | |
364 | ||
365 | /* Read other side\'s version identification. */ | |
366 | for (;;) { | |
367 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
368 | int len = atomicio(read, connection_in, &buf[i], 1); | |
369 | if (len < 0) | |
370 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); | |
371 | if (len != 1) | |
372 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
373 | if (buf[i] == '\r') { | |
374 | buf[i] = '\n'; | |
375 | buf[i + 1] = 0; | |
376 | continue; /**XXX wait for \n */ | |
377 | } | |
378 | if (buf[i] == '\n') { | |
379 | buf[i + 1] = 0; | |
380 | break; | |
381 | } | |
382 | } | |
383 | buf[sizeof(buf) - 1] = 0; | |
384 | if (strncmp(buf, "SSH-", 4) == 0) | |
385 | break; | |
386 | debug("ssh_exchange_identification: %s", buf); | |
387 | } | |
388 | server_version_string = xstrdup(buf); | |
389 | ||
390 | /* | |
391 | * Check that the versions match. In future this might accept | |
392 | * several versions and set appropriate flags to handle them. | |
393 | */ | |
394 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", | |
395 | &remote_major, &remote_minor, remote_version) != 3) | |
396 | fatal("Bad remote protocol version identification: '%.100s'", buf); | |
397 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
398 | remote_major, remote_minor, remote_version); | |
399 | ||
400 | compat_datafellows(remote_version); | |
401 | mismatch = 0; | |
402 | ||
403 | switch (remote_major) { | |
404 | case 1: | |
405 | if (remote_minor == 99 && | |
406 | (options.protocol & SSH_PROTO_2) && | |
407 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
408 | enable_compat20(); | |
409 | break; | |
410 | } | |
411 | if (!(options.protocol & SSH_PROTO_1)) { | |
412 | mismatch = 1; | |
413 | break; | |
414 | } | |
415 | if (remote_minor < 3) { | |
416 | fatal("Remote machine has too old SSH software version."); | |
417 | } else if (remote_minor == 3 || remote_minor == 4) { | |
418 | /* We speak 1.3, too. */ | |
419 | enable_compat13(); | |
420 | minor1 = 3; | |
421 | if (options.forward_agent) { | |
422 | log("Agent forwarding disabled for protocol 1.3"); | |
423 | options.forward_agent = 0; | |
424 | } | |
425 | } | |
426 | break; | |
427 | case 2: | |
428 | if (options.protocol & SSH_PROTO_2) { | |
429 | enable_compat20(); | |
430 | break; | |
431 | } | |
432 | /* FALLTHROUGH */ | |
433 | default: | |
434 | mismatch = 1; | |
435 | break; | |
436 | } | |
437 | if (mismatch) | |
438 | fatal("Protocol major versions differ: %d vs. %d", | |
439 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, | |
440 | remote_major); | |
441 | /* Send our own protocol version identification. */ | |
442 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
443 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, | |
444 | compat20 ? PROTOCOL_MINOR_2 : minor1, | |
445 | SSH_VERSION); | |
446 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) | |
447 | fatal("write: %.100s", strerror(errno)); | |
448 | client_version_string = xstrdup(buf); | |
449 | chop(client_version_string); | |
450 | chop(server_version_string); | |
451 | debug("Local version string %.100s", client_version_string); | |
452 | } | |
453 | ||
454 | /* defaults to 'no' */ | |
455 | static int | |
456 | confirm(const char *prompt) | |
457 | { | |
458 | const char *msg, *again = "Please type 'yes' or 'no': "; | |
459 | char *p; | |
460 | int ret = -1; | |
461 | ||
462 | if (options.batch_mode) | |
463 | return 0; | |
464 | for (msg = prompt;;msg = again) { | |
465 | p = read_passphrase(msg, RP_ECHO); | |
466 | if (p == NULL || | |
467 | (p[0] == '\0') || (p[0] == '\n') || | |
468 | strncasecmp(p, "no", 2) == 0) | |
469 | ret = 0; | |
470 | if (p && strncasecmp(p, "yes", 3) == 0) | |
471 | ret = 1; | |
472 | if (p) | |
473 | xfree(p); | |
474 | if (ret != -1) | |
475 | return ret; | |
476 | } | |
477 | } | |
478 | ||
479 | /* | |
480 | * check whether the supplied host key is valid, return -1 if the key | |
481 | * is not valid. the user_hostfile will not be updated if 'readonly' is true. | |
482 | */ | |
483 | static int | |
484 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, | |
485 | int readonly, const char *user_hostfile, const char *system_hostfile) | |
486 | { | |
487 | Key *file_key; | |
488 | char *type = key_type(host_key); | |
489 | char *ip = NULL; | |
490 | char hostline[1000], *hostp, *fp; | |
491 | HostStatus host_status; | |
492 | HostStatus ip_status; | |
493 | int local = 0, host_ip_differ = 0; | |
494 | int salen; | |
495 | char ntop[NI_MAXHOST]; | |
496 | char msg[1024]; | |
497 | int len, host_line, ip_line; | |
498 | const char *host_file = NULL, *ip_file = NULL; | |
499 | ||
500 | /* | |
501 | * Force accepting of the host key for loopback/localhost. The | |
502 | * problem is that if the home directory is NFS-mounted to multiple | |
503 | * machines, localhost will refer to a different machine in each of | |
504 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
505 | * essentially disables host authentication for localhost; however, | |
506 | * this is probably not a real problem. | |
507 | */ | |
508 | /** hostaddr == 0! */ | |
509 | switch (hostaddr->sa_family) { | |
510 | case AF_INET: | |
511 | local = (ntohl(((struct sockaddr_in *)hostaddr)-> | |
512 | sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; | |
513 | salen = sizeof(struct sockaddr_in); | |
514 | break; | |
515 | case AF_INET6: | |
516 | local = IN6_IS_ADDR_LOOPBACK( | |
517 | &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
518 | salen = sizeof(struct sockaddr_in6); | |
519 | break; | |
520 | default: | |
521 | local = 0; | |
522 | salen = sizeof(struct sockaddr_storage); | |
523 | break; | |
524 | } | |
525 | if (options.no_host_authentication_for_localhost == 1 && local && | |
526 | options.host_key_alias == NULL) { | |
527 | debug("Forcing accepting of host key for " | |
528 | "loopback/localhost."); | |
529 | return 0; | |
530 | } | |
531 | ||
532 | /* | |
533 | * We don't have the remote ip-address for connections | |
534 | * using a proxy command | |
535 | */ | |
536 | if (options.proxy_command == NULL) { | |
537 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), | |
538 | NULL, 0, NI_NUMERICHOST) != 0) | |
539 | fatal("check_host_key: getnameinfo failed"); | |
540 | ip = xstrdup(ntop); | |
541 | } else { | |
542 | ip = xstrdup("<no hostip for proxy command>"); | |
543 | } | |
544 | /* | |
545 | * Turn off check_host_ip if the connection is to localhost, via proxy | |
546 | * command or if we don't have a hostname to compare with | |
547 | */ | |
548 | if (options.check_host_ip && | |
549 | (local || strcmp(host, ip) == 0 || options.proxy_command != NULL)) | |
550 | options.check_host_ip = 0; | |
551 | ||
552 | /* | |
553 | * Allow the user to record the key under a different name. This is | |
554 | * useful for ssh tunneling over forwarded connections or if you run | |
555 | * multiple sshd's on different ports on the same machine. | |
556 | */ | |
557 | if (options.host_key_alias != NULL) { | |
558 | host = options.host_key_alias; | |
559 | debug("using hostkeyalias: %s", host); | |
560 | } | |
561 | ||
562 | /* | |
563 | * Store the host key from the known host file in here so that we can | |
564 | * compare it with the key for the IP address. | |
565 | */ | |
566 | file_key = key_new(host_key->type); | |
567 | ||
568 | /* | |
569 | * Check if the host key is present in the user\'s list of known | |
570 | * hosts or in the systemwide list. | |
571 | */ | |
572 | host_file = user_hostfile; | |
573 | host_status = check_host_in_hostfile(host_file, host, host_key, | |
574 | file_key, &host_line); | |
575 | if (host_status == HOST_NEW) { | |
576 | host_file = system_hostfile; | |
577 | host_status = check_host_in_hostfile(host_file, host, host_key, | |
578 | file_key, &host_line); | |
579 | } | |
580 | /* | |
581 | * Also perform check for the ip address, skip the check if we are | |
582 | * localhost or the hostname was an ip address to begin with | |
583 | */ | |
584 | if (options.check_host_ip) { | |
585 | Key *ip_key = key_new(host_key->type); | |
586 | ||
587 | ip_file = user_hostfile; | |
588 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, | |
589 | ip_key, &ip_line); | |
590 | if (ip_status == HOST_NEW) { | |
591 | ip_file = system_hostfile; | |
592 | ip_status = check_host_in_hostfile(ip_file, ip, | |
593 | host_key, ip_key, &ip_line); | |
594 | } | |
595 | if (host_status == HOST_CHANGED && | |
596 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) | |
597 | host_ip_differ = 1; | |
598 | ||
599 | key_free(ip_key); | |
600 | } else | |
601 | ip_status = host_status; | |
602 | ||
603 | key_free(file_key); | |
604 | ||
605 | switch (host_status) { | |
606 | case HOST_OK: | |
607 | /* The host is known and the key matches. */ | |
608 | debug("Host '%.200s' is known and matches the %s host key.", | |
609 | host, type); | |
610 | debug("Found key in %s:%d", host_file, host_line); | |
611 | if (options.check_host_ip && ip_status == HOST_NEW) { | |
612 | if (readonly) | |
613 | log("%s host key for IP address " | |
614 | "'%.128s' not in list of known hosts.", | |
615 | type, ip); | |
616 | else if (!add_host_to_hostfile(user_hostfile, ip, | |
617 | host_key)) | |
618 | log("Failed to add the %s host key for IP " | |
619 | "address '%.128s' to the list of known " | |
620 | "hosts (%.30s).", type, ip, user_hostfile); | |
621 | else | |
622 | log("Warning: Permanently added the %s host " | |
623 | "key for IP address '%.128s' to the list " | |
624 | "of known hosts.", type, ip); | |
625 | } | |
626 | break; | |
627 | case HOST_NEW: | |
628 | if (readonly) | |
629 | goto fail; | |
630 | /* The host is new. */ | |
631 | if (options.strict_host_key_checking == 1) { | |
632 | /* | |
633 | * User has requested strict host key checking. We | |
634 | * will not add the host key automatically. The only | |
635 | * alternative left is to abort. | |
636 | */ | |
637 | error("No %s host key is known for %.200s and you " | |
638 | "have requested strict checking.", type, host); | |
639 | goto fail; | |
640 | } else if (options.strict_host_key_checking == 2) { | |
641 | /* The default */ | |
642 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); | |
643 | snprintf(msg, sizeof(msg), | |
644 | "The authenticity of host '%.200s (%s)' can't be " | |
645 | "established.\n" | |
646 | "%s key fingerprint is %s.\n" | |
647 | "Are you sure you want to continue connecting " | |
648 | "(yes/no)? ", host, ip, type, fp); | |
649 | xfree(fp); | |
650 | if (!confirm(msg)) | |
651 | goto fail; | |
652 | } | |
653 | if (options.check_host_ip && ip_status == HOST_NEW) { | |
654 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); | |
655 | hostp = hostline; | |
656 | } else | |
657 | hostp = host; | |
658 | ||
659 | /* | |
660 | * If not in strict mode, add the key automatically to the | |
661 | * local known_hosts file. | |
662 | */ | |
663 | if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) | |
664 | log("Failed to add the host to the list of known " | |
665 | "hosts (%.500s).", user_hostfile); | |
666 | else | |
667 | log("Warning: Permanently added '%.200s' (%s) to the " | |
668 | "list of known hosts.", hostp, type); | |
669 | break; | |
670 | case HOST_CHANGED: | |
671 | if (options.check_host_ip && host_ip_differ) { | |
672 | char *msg; | |
673 | if (ip_status == HOST_NEW) | |
674 | msg = "is unknown"; | |
675 | else if (ip_status == HOST_OK) | |
676 | msg = "is unchanged"; | |
677 | else | |
678 | msg = "has a different value"; | |
679 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
680 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
681 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
682 | error("The %s host key for %s has changed,", type, host); | |
683 | error("and the key for the according IP address %s", ip); | |
684 | error("%s. This could either mean that", msg); | |
685 | error("DNS SPOOFING is happening or the IP address for the host"); | |
686 | error("and its host key have changed at the same time."); | |
687 | if (ip_status != HOST_NEW) | |
688 | error("Offending key for IP in %s:%d", ip_file, ip_line); | |
689 | } | |
690 | /* The host key has changed. */ | |
691 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); | |
692 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
693 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); | |
694 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
695 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
696 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
697 | error("It is also possible that the %s host key has just been changed.", type); | |
698 | error("The fingerprint for the %s key sent by the remote host is\n%s.", | |
699 | type, fp); | |
700 | error("Please contact your system administrator."); | |
701 | error("Add correct host key in %.100s to get rid of this message.", | |
702 | user_hostfile); | |
703 | error("Offending key in %s:%d", host_file, host_line); | |
704 | xfree(fp); | |
705 | ||
706 | /* | |
707 | * If strict host key checking is in use, the user will have | |
708 | * to edit the key manually and we can only abort. | |
709 | */ | |
710 | if (options.strict_host_key_checking) { | |
711 | error("%s host key for %.200s has changed and you have " | |
712 | "requested strict checking.", type, host); | |
713 | goto fail; | |
714 | } | |
715 | ||
716 | /* | |
717 | * If strict host key checking has not been requested, allow | |
718 | * the connection but without password authentication or | |
719 | * agent forwarding. | |
720 | */ | |
721 | if (options.password_authentication) { | |
722 | error("Password authentication is disabled to avoid " | |
723 | "man-in-the-middle attacks."); | |
724 | options.password_authentication = 0; | |
725 | } | |
726 | if (options.forward_agent) { | |
727 | error("Agent forwarding is disabled to avoid " | |
728 | "man-in-the-middle attacks."); | |
729 | options.forward_agent = 0; | |
730 | } | |
731 | if (options.forward_x11) { | |
732 | error("X11 forwarding is disabled to avoid " | |
733 | "man-in-the-middle attacks."); | |
734 | options.forward_x11 = 0; | |
735 | } | |
736 | if (options.num_local_forwards > 0 || | |
737 | options.num_remote_forwards > 0) { | |
738 | error("Port forwarding is disabled to avoid " | |
739 | "man-in-the-middle attacks."); | |
740 | options.num_local_forwards = | |
741 | options.num_remote_forwards = 0; | |
742 | } | |
743 | /* | |
744 | * XXX Should permit the user to change to use the new id. | |
745 | * This could be done by converting the host key to an | |
746 | * identifying sentence, tell that the host identifies itself | |
747 | * by that sentence, and ask the user if he/she whishes to | |
748 | * accept the authentication. | |
749 | */ | |
750 | break; | |
751 | } | |
752 | ||
753 | if (options.check_host_ip && host_status != HOST_CHANGED && | |
754 | ip_status == HOST_CHANGED) { | |
755 | snprintf(msg, sizeof(msg), | |
756 | "Warning: the %s host key for '%.200s' " | |
757 | "differs from the key for the IP address '%.128s'" | |
758 | "\nOffending key for IP in %s:%d", | |
759 | type, host, ip, ip_file, ip_line); | |
760 | if (host_status == HOST_OK) { | |
761 | len = strlen(msg); | |
762 | snprintf(msg + len, sizeof(msg) - len, | |
763 | "\nMatching host key in %s:%d", | |
764 | host_file, host_line); | |
765 | } | |
766 | if (options.strict_host_key_checking == 1) { | |
767 | log(msg); | |
768 | error("Exiting, you have requested strict checking."); | |
769 | goto fail; | |
770 | } else if (options.strict_host_key_checking == 2) { | |
771 | strlcat(msg, "\nAre you sure you want " | |
772 | "to continue connecting (yes/no)? ", sizeof(msg)); | |
773 | if (!confirm(msg)) | |
774 | goto fail; | |
775 | } else { | |
776 | log(msg); | |
777 | } | |
778 | } | |
779 | ||
780 | xfree(ip); | |
781 | return 0; | |
782 | ||
783 | fail: | |
784 | xfree(ip); | |
785 | return -1; | |
786 | } | |
787 | ||
788 | int | |
789 | verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) | |
790 | { | |
791 | struct stat st; | |
792 | ||
793 | /* return ok if the key can be found in an old keyfile */ | |
794 | if (stat(options.system_hostfile2, &st) == 0 || | |
795 | stat(options.user_hostfile2, &st) == 0) { | |
796 | if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1, | |
797 | options.user_hostfile2, options.system_hostfile2) == 0) | |
798 | return 0; | |
799 | } | |
800 | return check_host_key(host, hostaddr, host_key, /*readonly*/ 0, | |
801 | options.user_hostfile, options.system_hostfile); | |
802 | } | |
803 | ||
804 | /* | |
805 | * Starts a dialog with the server, and authenticates the current user on the | |
806 | * server. This does not need any extra privileges. The basic connection | |
807 | * to the server must already have been established before this is called. | |
808 | * If login fails, this function prints an error and never returns. | |
809 | * This function does not require super-user privileges. | |
810 | */ | |
811 | void | |
812 | ssh_login(Sensitive *sensitive, const char *orighost, | |
813 | struct sockaddr *hostaddr, struct passwd *pw) | |
814 | { | |
815 | char *host, *cp; | |
816 | char *server_user, *local_user; | |
817 | ||
818 | local_user = xstrdup(pw->pw_name); | |
819 | server_user = options.user ? options.user : local_user; | |
820 | ||
821 | /* Convert the user-supplied hostname into all lowercase. */ | |
822 | host = xstrdup(orighost); | |
823 | for (cp = host; *cp; cp++) | |
824 | if (isupper(*cp)) | |
825 | *cp = tolower(*cp); | |
826 | ||
827 | /* Exchange protocol version identification strings with the server. */ | |
828 | ssh_exchange_identification(); | |
829 | ||
830 | /* Put the connection into non-blocking mode. */ | |
831 | packet_set_nonblocking(); | |
832 | ||
833 | /* key exchange */ | |
834 | /* authenticate user */ | |
835 | if (compat20) { | |
836 | ssh_kex2(host, hostaddr); | |
837 | ssh_userauth2(local_user, server_user, host, sensitive); | |
838 | } else { | |
839 | ssh_kex(host, hostaddr); | |
840 | ssh_userauth1(local_user, server_user, host, sensitive); | |
841 | } | |
842 | } | |
843 | ||
844 | void | |
845 | ssh_put_password(char *password) | |
846 | { | |
847 | int size; | |
848 | char *padded; | |
849 | ||
850 | if (datafellows & SSH_BUG_PASSWORDPAD) { | |
851 | packet_put_cstring(password); | |
852 | return; | |
853 | } | |
854 | size = roundup(strlen(password) + 1, 32); | |
855 | padded = xmalloc(size); | |
856 | memset(padded, 0, size); | |
857 | strlcpy(padded, password, size); | |
858 | packet_put_string(padded, size); | |
859 | memset(padded, 0, size); | |
860 | xfree(padded); | |
861 | } |