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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 | * Created: Sat Mar 18 22:15:47 1995 ylo | |
6 | * Code to connect to a remote host, and to perform the client side of the | |
7 | * login (authentication) dialog. | |
8 | */ | |
9 | ||
10 | #include "includes.h" | |
11 | RCSID("$OpenBSD: sshconnect.c,v 1.77 2000/08/28 03:50:54 deraadt Exp $"); | |
12 | ||
13 | #include <openssl/bn.h> | |
14 | #include <openssl/dsa.h> | |
15 | #include <openssl/rsa.h> | |
16 | ||
17 | #include "xmalloc.h" | |
18 | #include "rsa.h" | |
19 | #include "ssh.h" | |
20 | #include "buffer.h" | |
21 | #include "packet.h" | |
22 | #include "uidswap.h" | |
23 | #include "compat.h" | |
24 | #include "readconf.h" | |
25 | #include "key.h" | |
26 | #include "sshconnect.h" | |
27 | #include "hostfile.h" | |
28 | ||
29 | char *client_version_string = NULL; | |
30 | char *server_version_string = NULL; | |
31 | ||
32 | extern Options options; | |
33 | #ifdef HAVE___PROGNAME | |
34 | extern char *__progname; | |
35 | #else /* HAVE___PROGNAME */ | |
36 | static const char *__progname = "ssh"; | |
37 | #endif /* HAVE___PROGNAME */ | |
38 | ||
39 | /* | |
40 | * Connect to the given ssh server using a proxy command. | |
41 | */ | |
42 | int | |
43 | ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid, | |
44 | const char *proxy_command) | |
45 | { | |
46 | Buffer command; | |
47 | const char *cp; | |
48 | char *command_string; | |
49 | int pin[2], pout[2]; | |
50 | pid_t pid; | |
51 | char strport[NI_MAXSERV]; | |
52 | ||
53 | /* Convert the port number into a string. */ | |
54 | snprintf(strport, sizeof strport, "%hu", port); | |
55 | ||
56 | /* Build the final command string in the buffer by making the | |
57 | appropriate substitutions to the given proxy command. */ | |
58 | buffer_init(&command); | |
59 | for (cp = proxy_command; *cp; cp++) { | |
60 | if (cp[0] == '%' && cp[1] == '%') { | |
61 | buffer_append(&command, "%", 1); | |
62 | cp++; | |
63 | continue; | |
64 | } | |
65 | if (cp[0] == '%' && cp[1] == 'h') { | |
66 | buffer_append(&command, host, strlen(host)); | |
67 | cp++; | |
68 | continue; | |
69 | } | |
70 | if (cp[0] == '%' && cp[1] == 'p') { | |
71 | buffer_append(&command, strport, strlen(strport)); | |
72 | cp++; | |
73 | continue; | |
74 | } | |
75 | buffer_append(&command, cp, 1); | |
76 | } | |
77 | buffer_append(&command, "\0", 1); | |
78 | ||
79 | /* Get the final command string. */ | |
80 | command_string = buffer_ptr(&command); | |
81 | ||
82 | /* Create pipes for communicating with the proxy. */ | |
83 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
84 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
85 | strerror(errno)); | |
86 | ||
87 | debug("Executing proxy command: %.500s", command_string); | |
88 | ||
89 | /* Fork and execute the proxy command. */ | |
90 | if ((pid = fork()) == 0) { | |
91 | char *argv[10]; | |
92 | ||
93 | /* Child. Permanently give up superuser privileges. */ | |
94 | permanently_set_uid(original_real_uid); | |
95 | ||
96 | /* Redirect stdin and stdout. */ | |
97 | close(pin[1]); | |
98 | if (pin[0] != 0) { | |
99 | if (dup2(pin[0], 0) < 0) | |
100 | perror("dup2 stdin"); | |
101 | close(pin[0]); | |
102 | } | |
103 | close(pout[0]); | |
104 | if (dup2(pout[1], 1) < 0) | |
105 | perror("dup2 stdout"); | |
106 | /* Cannot be 1 because pin allocated two descriptors. */ | |
107 | close(pout[1]); | |
108 | ||
109 | /* Stderr is left as it is so that error messages get | |
110 | printed on the user's terminal. */ | |
111 | argv[0] = _PATH_BSHELL; | |
112 | argv[1] = "-c"; | |
113 | argv[2] = command_string; | |
114 | argv[3] = NULL; | |
115 | ||
116 | /* Execute the proxy command. Note that we gave up any | |
117 | extra privileges above. */ | |
118 | execv(_PATH_BSHELL, argv); | |
119 | perror(_PATH_BSHELL); | |
120 | exit(1); | |
121 | } | |
122 | /* Parent. */ | |
123 | if (pid < 0) | |
124 | fatal("fork failed: %.100s", strerror(errno)); | |
125 | ||
126 | /* Close child side of the descriptors. */ | |
127 | close(pin[0]); | |
128 | close(pout[1]); | |
129 | ||
130 | /* Free the command name. */ | |
131 | buffer_free(&command); | |
132 | ||
133 | /* Set the connection file descriptors. */ | |
134 | packet_set_connection(pout[0], pin[1]); | |
135 | ||
136 | return 1; | |
137 | } | |
138 | ||
139 | /* | |
140 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
141 | */ | |
142 | int | |
143 | ssh_create_socket(uid_t original_real_uid, int privileged, int family) | |
144 | { | |
145 | int sock; | |
146 | ||
147 | /* | |
148 | * If we are running as root and want to connect to a privileged | |
149 | * port, bind our own socket to a privileged port. | |
150 | */ | |
151 | if (privileged) { | |
152 | int p = IPPORT_RESERVED - 1; | |
153 | sock = rresvport_af(&p, family); | |
154 | if (sock < 0) | |
155 | error("rresvport: af=%d %.100s", family, strerror(errno)); | |
156 | else | |
157 | debug("Allocated local port %d.", p); | |
158 | } else { | |
159 | /* | |
160 | * Just create an ordinary socket on arbitrary port. We use | |
161 | * the user's uid to create the socket. | |
162 | */ | |
163 | temporarily_use_uid(original_real_uid); | |
164 | sock = socket(family, SOCK_STREAM, 0); | |
165 | if (sock < 0) | |
166 | error("socket: %.100s", strerror(errno)); | |
167 | restore_uid(); | |
168 | } | |
169 | return sock; | |
170 | } | |
171 | ||
172 | /* | |
173 | * Opens a TCP/IP connection to the remote server on the given host. | |
174 | * The address of the remote host will be returned in hostaddr. | |
175 | * If port is 0, the default port will be used. If anonymous is zero, | |
176 | * a privileged port will be allocated to make the connection. | |
177 | * This requires super-user privileges if anonymous is false. | |
178 | * Connection_attempts specifies the maximum number of tries (one per | |
179 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
180 | * and %p substituted for host and port, respectively) to use to contact | |
181 | * the daemon. | |
182 | */ | |
183 | int | |
184 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, | |
185 | u_short port, int connection_attempts, | |
186 | int anonymous, uid_t original_real_uid, | |
187 | const char *proxy_command) | |
188 | { | |
189 | int sock = -1, attempt; | |
190 | struct servent *sp; | |
191 | struct addrinfo hints, *ai, *aitop; | |
192 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
193 | int gaierr; | |
194 | struct linger linger; | |
195 | ||
196 | debug("ssh_connect: getuid %u geteuid %u anon %d", | |
197 | (u_int) getuid(), (u_int) geteuid(), anonymous); | |
198 | ||
199 | /* Get default port if port has not been set. */ | |
200 | if (port == 0) { | |
201 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
202 | if (sp) | |
203 | port = ntohs(sp->s_port); | |
204 | else | |
205 | port = SSH_DEFAULT_PORT; | |
206 | } | |
207 | /* If a proxy command is given, connect using it. */ | |
208 | if (proxy_command != NULL) | |
209 | return ssh_proxy_connect(host, port, original_real_uid, proxy_command); | |
210 | ||
211 | /* No proxy command. */ | |
212 | ||
213 | memset(&hints, 0, sizeof(hints)); | |
214 | hints.ai_family = IPv4or6; | |
215 | hints.ai_socktype = SOCK_STREAM; | |
216 | snprintf(strport, sizeof strport, "%d", port); | |
217 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) | |
218 | fatal("%s: %.100s: %s", __progname, host, | |
219 | gai_strerror(gaierr)); | |
220 | ||
221 | /* | |
222 | * Try to connect several times. On some machines, the first time | |
223 | * will sometimes fail. In general socket code appears to behave | |
224 | * quite magically on many machines. | |
225 | */ | |
226 | for (attempt = 0; attempt < connection_attempts; attempt++) { | |
227 | if (attempt > 0) | |
228 | debug("Trying again..."); | |
229 | ||
230 | /* Loop through addresses for this host, and try each one in | |
231 | sequence until the connection succeeds. */ | |
232 | for (ai = aitop; ai; ai = ai->ai_next) { | |
233 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
234 | continue; | |
235 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
236 | ntop, sizeof(ntop), strport, sizeof(strport), | |
237 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
238 | error("ssh_connect: getnameinfo failed"); | |
239 | continue; | |
240 | } | |
241 | debug("Connecting to %.200s [%.100s] port %s.", | |
242 | host, ntop, strport); | |
243 | ||
244 | /* Create a socket for connecting. */ | |
245 | sock = ssh_create_socket(original_real_uid, | |
246 | #ifdef HAVE_CYGWIN | |
247 | !anonymous && port < IPPORT_RESERVED, | |
248 | #else | |
249 | !anonymous && geteuid() == 0 && port < IPPORT_RESERVED, | |
250 | #endif | |
251 | ai->ai_family); | |
252 | if (sock < 0) | |
253 | continue; | |
254 | ||
255 | /* Connect to the host. We use the user's uid in the | |
256 | * hope that it will help with tcp_wrappers showing | |
257 | * the remote uid as root. | |
258 | */ | |
259 | temporarily_use_uid(original_real_uid); | |
260 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { | |
261 | /* Successful connection. */ | |
262 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); | |
263 | restore_uid(); | |
264 | break; | |
265 | } else { | |
266 | debug("connect: %.100s", strerror(errno)); | |
267 | restore_uid(); | |
268 | /* | |
269 | * Close the failed socket; there appear to | |
270 | * be some problems when reusing a socket for | |
271 | * which connect() has already returned an | |
272 | * error. | |
273 | */ | |
274 | shutdown(sock, SHUT_RDWR); | |
275 | close(sock); | |
276 | } | |
277 | } | |
278 | if (ai) | |
279 | break; /* Successful connection. */ | |
280 | ||
281 | /* Sleep a moment before retrying. */ | |
282 | sleep(1); | |
283 | } | |
284 | ||
285 | freeaddrinfo(aitop); | |
286 | ||
287 | /* Return failure if we didn't get a successful connection. */ | |
288 | if (attempt >= connection_attempts) | |
289 | return 0; | |
290 | ||
291 | debug("Connection established."); | |
292 | ||
293 | /* | |
294 | * Set socket options. We would like the socket to disappear as soon | |
295 | * as it has been closed for whatever reason. | |
296 | */ | |
297 | /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
298 | linger.l_onoff = 1; | |
299 | linger.l_linger = 5; | |
300 | setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
301 | ||
302 | /* Set the connection. */ | |
303 | packet_set_connection(sock, sock); | |
304 | ||
305 | return 1; | |
306 | } | |
307 | ||
308 | /* | |
309 | * Waits for the server identification string, and sends our own | |
310 | * identification string. | |
311 | */ | |
312 | void | |
313 | ssh_exchange_identification() | |
314 | { | |
315 | char buf[256], remote_version[256]; /* must be same size! */ | |
316 | int remote_major, remote_minor, i, mismatch; | |
317 | int connection_in = packet_get_connection_in(); | |
318 | int connection_out = packet_get_connection_out(); | |
319 | ||
320 | /* Read other side\'s version identification. */ | |
321 | for (;;) { | |
322 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
323 | int len = atomicio(read, connection_in, &buf[i], 1); | |
324 | if (len < 0) | |
325 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); | |
326 | if (len != 1) | |
327 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
328 | if (buf[i] == '\r') { | |
329 | buf[i] = '\n'; | |
330 | buf[i + 1] = 0; | |
331 | continue; /**XXX wait for \n */ | |
332 | } | |
333 | if (buf[i] == '\n') { | |
334 | buf[i + 1] = 0; | |
335 | break; | |
336 | } | |
337 | } | |
338 | buf[sizeof(buf) - 1] = 0; | |
339 | if (strncmp(buf, "SSH-", 4) == 0) | |
340 | break; | |
341 | debug("ssh_exchange_identification: %s", buf); | |
342 | } | |
343 | server_version_string = xstrdup(buf); | |
344 | ||
345 | /* | |
346 | * Check that the versions match. In future this might accept | |
347 | * several versions and set appropriate flags to handle them. | |
348 | */ | |
349 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", | |
350 | &remote_major, &remote_minor, remote_version) != 3) | |
351 | fatal("Bad remote protocol version identification: '%.100s'", buf); | |
352 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
353 | remote_major, remote_minor, remote_version); | |
354 | ||
355 | compat_datafellows(remote_version); | |
356 | mismatch = 0; | |
357 | ||
358 | switch(remote_major) { | |
359 | case 1: | |
360 | if (remote_minor == 99 && | |
361 | (options.protocol & SSH_PROTO_2) && | |
362 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
363 | enable_compat20(); | |
364 | break; | |
365 | } | |
366 | if (!(options.protocol & SSH_PROTO_1)) { | |
367 | mismatch = 1; | |
368 | break; | |
369 | } | |
370 | if (remote_minor < 3) { | |
371 | fatal("Remote machine has too old SSH software version."); | |
372 | } else if (remote_minor == 3) { | |
373 | /* We speak 1.3, too. */ | |
374 | enable_compat13(); | |
375 | if (options.forward_agent) { | |
376 | log("Agent forwarding disabled for protocol 1.3"); | |
377 | options.forward_agent = 0; | |
378 | } | |
379 | } | |
380 | break; | |
381 | case 2: | |
382 | if (options.protocol & SSH_PROTO_2) { | |
383 | enable_compat20(); | |
384 | break; | |
385 | } | |
386 | /* FALLTHROUGH */ | |
387 | default: | |
388 | mismatch = 1; | |
389 | break; | |
390 | } | |
391 | if (mismatch) | |
392 | fatal("Protocol major versions differ: %d vs. %d", | |
393 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, | |
394 | remote_major); | |
395 | if (compat20) | |
396 | packet_set_ssh2_format(); | |
397 | /* Send our own protocol version identification. */ | |
398 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
399 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, | |
400 | compat20 ? PROTOCOL_MINOR_2 : PROTOCOL_MINOR_1, | |
401 | SSH_VERSION); | |
402 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) | |
403 | fatal("write: %.100s", strerror(errno)); | |
404 | client_version_string = xstrdup(buf); | |
405 | chop(client_version_string); | |
406 | chop(server_version_string); | |
407 | debug("Local version string %.100s", client_version_string); | |
408 | } | |
409 | ||
410 | int | |
411 | read_yes_or_no(const char *prompt, int defval) | |
412 | { | |
413 | char buf[1024]; | |
414 | FILE *f; | |
415 | int retval = -1; | |
416 | ||
417 | if (isatty(0)) | |
418 | f = stdin; | |
419 | else | |
420 | f = fopen("/dev/tty", "rw"); | |
421 | ||
422 | if (f == NULL) | |
423 | return 0; | |
424 | ||
425 | fflush(stdout); | |
426 | ||
427 | while (1) { | |
428 | fprintf(stderr, "%s", prompt); | |
429 | if (fgets(buf, sizeof(buf), f) == NULL) { | |
430 | /* Print a newline (the prompt probably didn\'t have one). */ | |
431 | fprintf(stderr, "\n"); | |
432 | strlcpy(buf, "no", sizeof buf); | |
433 | } | |
434 | /* Remove newline from response. */ | |
435 | if (strchr(buf, '\n')) | |
436 | *strchr(buf, '\n') = 0; | |
437 | ||
438 | if (buf[0] == 0) | |
439 | retval = defval; | |
440 | if (strcmp(buf, "yes") == 0) | |
441 | retval = 1; | |
442 | if (strcmp(buf, "no") == 0) | |
443 | retval = 0; | |
444 | ||
445 | if (retval != -1) { | |
446 | if (f != stdin) | |
447 | fclose(f); | |
448 | return retval; | |
449 | } | |
450 | } | |
451 | } | |
452 | ||
453 | /* | |
454 | * check whether the supplied host key is valid, return only if ok. | |
455 | */ | |
456 | ||
457 | void | |
458 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, | |
459 | const char *user_hostfile, const char *system_hostfile) | |
460 | { | |
461 | Key *file_key; | |
462 | char *type = key_type(host_key); | |
463 | char *ip = NULL; | |
464 | char hostline[1000], *hostp; | |
465 | HostStatus host_status; | |
466 | HostStatus ip_status; | |
467 | int local = 0, host_ip_differ = 0; | |
468 | int salen; | |
469 | char ntop[NI_MAXHOST]; | |
470 | ||
471 | /* | |
472 | * Force accepting of the host key for loopback/localhost. The | |
473 | * problem is that if the home directory is NFS-mounted to multiple | |
474 | * machines, localhost will refer to a different machine in each of | |
475 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
476 | * essentially disables host authentication for localhost; however, | |
477 | * this is probably not a real problem. | |
478 | */ | |
479 | /** hostaddr == 0! */ | |
480 | switch (hostaddr->sa_family) { | |
481 | case AF_INET: | |
482 | local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; | |
483 | salen = sizeof(struct sockaddr_in); | |
484 | break; | |
485 | case AF_INET6: | |
486 | local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
487 | salen = sizeof(struct sockaddr_in6); | |
488 | break; | |
489 | default: | |
490 | local = 0; | |
491 | salen = sizeof(struct sockaddr_storage); | |
492 | break; | |
493 | } | |
494 | if (local) { | |
495 | debug("Forcing accepting of host key for loopback/localhost."); | |
496 | return; | |
497 | } | |
498 | ||
499 | /* | |
500 | * Turn off check_host_ip for proxy connects, since | |
501 | * we don't have the remote ip-address | |
502 | */ | |
503 | if (options.proxy_command != NULL && options.check_host_ip) | |
504 | options.check_host_ip = 0; | |
505 | ||
506 | if (options.check_host_ip) { | |
507 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), | |
508 | NULL, 0, NI_NUMERICHOST) != 0) | |
509 | fatal("check_host_key: getnameinfo failed"); | |
510 | ip = xstrdup(ntop); | |
511 | } | |
512 | ||
513 | /* | |
514 | * Store the host key from the known host file in here so that we can | |
515 | * compare it with the key for the IP address. | |
516 | */ | |
517 | file_key = key_new(host_key->type); | |
518 | ||
519 | /* | |
520 | * Check if the host key is present in the user\'s list of known | |
521 | * hosts or in the systemwide list. | |
522 | */ | |
523 | host_status = check_host_in_hostfile(user_hostfile, host, host_key, file_key); | |
524 | if (host_status == HOST_NEW) | |
525 | host_status = check_host_in_hostfile(system_hostfile, host, host_key, file_key); | |
526 | /* | |
527 | * Also perform check for the ip address, skip the check if we are | |
528 | * localhost or the hostname was an ip address to begin with | |
529 | */ | |
530 | if (options.check_host_ip && !local && strcmp(host, ip)) { | |
531 | Key *ip_key = key_new(host_key->type); | |
532 | ip_status = check_host_in_hostfile(user_hostfile, ip, host_key, ip_key); | |
533 | ||
534 | if (ip_status == HOST_NEW) | |
535 | ip_status = check_host_in_hostfile(system_hostfile, ip, host_key, ip_key); | |
536 | if (host_status == HOST_CHANGED && | |
537 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) | |
538 | host_ip_differ = 1; | |
539 | ||
540 | key_free(ip_key); | |
541 | } else | |
542 | ip_status = host_status; | |
543 | ||
544 | key_free(file_key); | |
545 | ||
546 | switch (host_status) { | |
547 | case HOST_OK: | |
548 | /* The host is known and the key matches. */ | |
549 | debug("Host '%.200s' is known and matches the %s host key.", | |
550 | host, type); | |
551 | if (options.check_host_ip) { | |
552 | if (ip_status == HOST_NEW) { | |
553 | if (!add_host_to_hostfile(user_hostfile, ip, host_key)) | |
554 | log("Failed to add the %s host key for IP address '%.30s' to the list of known hosts (%.30s).", | |
555 | type, ip, user_hostfile); | |
556 | else | |
557 | log("Warning: Permanently added the %s host key for IP address '%.30s' to the list of known hosts.", | |
558 | type, ip); | |
559 | } else if (ip_status != HOST_OK) | |
560 | log("Warning: the %s host key for '%.200s' differs from the key for the IP address '%.30s'", | |
561 | type, host, ip); | |
562 | } | |
563 | break; | |
564 | case HOST_NEW: | |
565 | /* The host is new. */ | |
566 | if (options.strict_host_key_checking == 1) { | |
567 | /* User has requested strict host key checking. We will not add the host key | |
568 | automatically. The only alternative left is to abort. */ | |
569 | fatal("No %s host key is known for %.200s and you have requested strict checking.", type, host); | |
570 | } else if (options.strict_host_key_checking == 2) { | |
571 | /* The default */ | |
572 | char prompt[1024]; | |
573 | char *fp = key_fingerprint(host_key); | |
574 | snprintf(prompt, sizeof(prompt), | |
575 | "The authenticity of host '%.200s' can't be established.\n" | |
576 | "%s key fingerprint is %s.\n" | |
577 | "Are you sure you want to continue connecting (yes/no)? ", | |
578 | host, type, fp); | |
579 | if (!read_yes_or_no(prompt, -1)) | |
580 | fatal("Aborted by user!\n"); | |
581 | } | |
582 | if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) { | |
583 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); | |
584 | hostp = hostline; | |
585 | } else | |
586 | hostp = host; | |
587 | ||
588 | /* If not in strict mode, add the key automatically to the local known_hosts file. */ | |
589 | if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) | |
590 | log("Failed to add the host to the list of known hosts (%.500s).", | |
591 | user_hostfile); | |
592 | else | |
593 | log("Warning: Permanently added '%.200s' (%s) to the list of known hosts.", | |
594 | hostp, type); | |
595 | break; | |
596 | case HOST_CHANGED: | |
597 | if (options.check_host_ip && host_ip_differ) { | |
598 | char *msg; | |
599 | if (ip_status == HOST_NEW) | |
600 | msg = "is unknown"; | |
601 | else if (ip_status == HOST_OK) | |
602 | msg = "is unchanged"; | |
603 | else | |
604 | msg = "has a different value"; | |
605 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
606 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
607 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
608 | error("The %s host key for %s has changed,", type, host); | |
609 | error("and the key for the according IP address %s", ip); | |
610 | error("%s. This could either mean that", msg); | |
611 | error("DNS SPOOFING is happening or the IP address for the host"); | |
612 | error("and its host key have changed at the same time"); | |
613 | } | |
614 | /* The host key has changed. */ | |
615 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
616 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); | |
617 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
618 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
619 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
620 | error("It is also possible that the %s host key has just been changed.", type); | |
621 | error("Please contact your system administrator."); | |
622 | error("Add correct host key in %.100s to get rid of this message.", | |
623 | user_hostfile); | |
624 | ||
625 | /* | |
626 | * If strict host key checking is in use, the user will have | |
627 | * to edit the key manually and we can only abort. | |
628 | */ | |
629 | if (options.strict_host_key_checking) | |
630 | fatal("%s host key for %.200s has changed and you have requested strict checking.", type, host); | |
631 | ||
632 | /* | |
633 | * If strict host key checking has not been requested, allow | |
634 | * the connection but without password authentication or | |
635 | * agent forwarding. | |
636 | */ | |
637 | if (options.password_authentication) { | |
638 | error("Password authentication is disabled to avoid trojan horses."); | |
639 | options.password_authentication = 0; | |
640 | } | |
641 | if (options.forward_agent) { | |
642 | error("Agent forwarding is disabled to avoid trojan horses."); | |
643 | options.forward_agent = 0; | |
644 | } | |
645 | /* | |
646 | * XXX Should permit the user to change to use the new id. | |
647 | * This could be done by converting the host key to an | |
648 | * identifying sentence, tell that the host identifies itself | |
649 | * by that sentence, and ask the user if he/she whishes to | |
650 | * accept the authentication. | |
651 | */ | |
652 | break; | |
653 | } | |
654 | if (options.check_host_ip) | |
655 | xfree(ip); | |
656 | } | |
657 | ||
658 | /* | |
659 | * Starts a dialog with the server, and authenticates the current user on the | |
660 | * server. This does not need any extra privileges. The basic connection | |
661 | * to the server must already have been established before this is called. | |
662 | * If login fails, this function prints an error and never returns. | |
663 | * This function does not require super-user privileges. | |
664 | */ | |
665 | void | |
666 | ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost, | |
667 | struct sockaddr *hostaddr, uid_t original_real_uid) | |
668 | { | |
669 | struct passwd *pw; | |
670 | char *host, *cp; | |
671 | char *server_user, *local_user; | |
672 | ||
673 | /* Get local user name. Use it as server user if no user name was given. */ | |
674 | pw = getpwuid(original_real_uid); | |
675 | if (!pw) | |
676 | fatal("User id %u not found from user database.", original_real_uid); | |
677 | local_user = xstrdup(pw->pw_name); | |
678 | server_user = options.user ? options.user : local_user; | |
679 | ||
680 | /* Convert the user-supplied hostname into all lowercase. */ | |
681 | host = xstrdup(orighost); | |
682 | for (cp = host; *cp; cp++) | |
683 | if (isupper(*cp)) | |
684 | *cp = tolower(*cp); | |
685 | ||
686 | /* Exchange protocol version identification strings with the server. */ | |
687 | ssh_exchange_identification(); | |
688 | ||
689 | /* Put the connection into non-blocking mode. */ | |
690 | packet_set_nonblocking(); | |
691 | ||
692 | /* key exchange */ | |
693 | /* authenticate user */ | |
694 | if (compat20) { | |
695 | ssh_kex2(host, hostaddr); | |
696 | ssh_userauth2(server_user, host); | |
697 | } else { | |
698 | ssh_kex(host, hostaddr); | |
699 | ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key); | |
700 | } | |
701 | } |