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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" | |
665a873d | 16 | RCSID("$OpenBSD: sshconnect.c,v 1.168 2005/07/17 07:17:55 djm 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" | |
34 | ||
0fff78ff | 35 | #include "dns.h" |
0fff78ff | 36 | |
3c0ef626 | 37 | char *client_version_string = NULL; |
38 | char *server_version_string = NULL; | |
39 | ||
cdd66111 | 40 | int matching_host_key_dns = 0; |
0fff78ff | 41 | |
f5799ae1 | 42 | /* import */ |
3c0ef626 | 43 | extern Options options; |
44 | extern char *__progname; | |
f5799ae1 | 45 | extern uid_t original_real_uid; |
46 | extern uid_t original_effective_uid; | |
41b2f314 | 47 | extern pid_t proxy_command_pid; |
3c0ef626 | 48 | |
49 | #ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */ | |
50 | #define INET6_ADDRSTRLEN 46 | |
51 | #endif | |
52 | ||
41b2f314 | 53 | static int show_other_keys(const char *, Key *); |
cdd66111 | 54 | static void warn_changed_key(Key *); |
3c0ef626 | 55 | |
56 | /* | |
57 | * Connect to the given ssh server using a proxy command. | |
58 | */ | |
59 | static int | |
f5799ae1 | 60 | ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) |
3c0ef626 | 61 | { |
665a873d | 62 | char *command_string, *tmp; |
3c0ef626 | 63 | int pin[2], pout[2]; |
64 | pid_t pid; | |
65 | char strport[NI_MAXSERV]; | |
665a873d | 66 | size_t len; |
3c0ef626 | 67 | |
68 | /* Convert the port number into a string. */ | |
69 | snprintf(strport, sizeof strport, "%hu", port); | |
70 | ||
41b2f314 | 71 | /* |
72 | * Build the final command string in the buffer by making the | |
73 | * appropriate substitutions to the given proxy command. | |
74 | * | |
cdd66111 | 75 | * Use "exec" to avoid "sh -c" processes on some platforms |
41b2f314 | 76 | * (e.g. Solaris) |
77 | */ | |
665a873d | 78 | len = strlen(proxy_command) + 6; |
79 | tmp = xmalloc(len); | |
80 | strlcpy(tmp, "exec ", len); | |
81 | strlcat(tmp, proxy_command, len); | |
82 | command_string = percent_expand(tmp, "h", host, | |
83 | "p", strport, (char *)NULL); | |
84 | xfree(tmp); | |
3c0ef626 | 85 | |
86 | /* Create pipes for communicating with the proxy. */ | |
87 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
88 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
e9a17296 | 89 | strerror(errno)); |
3c0ef626 | 90 | |
91 | debug("Executing proxy command: %.500s", command_string); | |
92 | ||
93 | /* Fork and execute the proxy command. */ | |
94 | if ((pid = fork()) == 0) { | |
95 | char *argv[10]; | |
96 | ||
97 | /* Child. Permanently give up superuser privileges. */ | |
f5799ae1 | 98 | seteuid(original_real_uid); |
99 | setuid(original_real_uid); | |
3c0ef626 | 100 | |
101 | /* Redirect stdin and stdout. */ | |
102 | close(pin[1]); | |
103 | if (pin[0] != 0) { | |
104 | if (dup2(pin[0], 0) < 0) | |
105 | perror("dup2 stdin"); | |
106 | close(pin[0]); | |
107 | } | |
108 | close(pout[0]); | |
109 | if (dup2(pout[1], 1) < 0) | |
110 | perror("dup2 stdout"); | |
111 | /* Cannot be 1 because pin allocated two descriptors. */ | |
112 | close(pout[1]); | |
113 | ||
114 | /* Stderr is left as it is so that error messages get | |
115 | printed on the user's terminal. */ | |
116 | argv[0] = _PATH_BSHELL; | |
117 | argv[1] = "-c"; | |
118 | argv[2] = command_string; | |
119 | argv[3] = NULL; | |
120 | ||
121 | /* Execute the proxy command. Note that we gave up any | |
122 | extra privileges above. */ | |
123 | execv(argv[0], argv); | |
124 | perror(argv[0]); | |
125 | exit(1); | |
126 | } | |
127 | /* Parent. */ | |
128 | if (pid < 0) | |
129 | fatal("fork failed: %.100s", strerror(errno)); | |
41b2f314 | 130 | else |
131 | proxy_command_pid = pid; /* save pid to clean up later */ | |
3c0ef626 | 132 | |
133 | /* Close child side of the descriptors. */ | |
134 | close(pin[0]); | |
135 | close(pout[1]); | |
136 | ||
137 | /* Free the command name. */ | |
665a873d | 138 | xfree(command_string); |
3c0ef626 | 139 | |
140 | /* Set the connection file descriptors. */ | |
141 | packet_set_connection(pout[0], pin[1]); | |
142 | ||
143 | /* Indicate OK return */ | |
144 | return 0; | |
145 | } | |
146 | ||
147 | /* | |
148 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
149 | */ | |
150 | static int | |
0fff78ff | 151 | ssh_create_socket(int privileged, struct addrinfo *ai) |
3c0ef626 | 152 | { |
153 | int sock, gaierr; | |
154 | struct addrinfo hints, *res; | |
155 | ||
156 | /* | |
157 | * If we are running as root and want to connect to a privileged | |
158 | * port, bind our own socket to a privileged port. | |
159 | */ | |
160 | if (privileged) { | |
161 | int p = IPPORT_RESERVED - 1; | |
f5799ae1 | 162 | PRIV_START; |
0fff78ff | 163 | sock = rresvport_af(&p, ai->ai_family); |
f5799ae1 | 164 | PRIV_END; |
3c0ef626 | 165 | if (sock < 0) |
0fff78ff | 166 | error("rresvport: af=%d %.100s", ai->ai_family, |
167 | strerror(errno)); | |
3c0ef626 | 168 | else |
169 | debug("Allocated local port %d.", p); | |
170 | return sock; | |
171 | } | |
0fff78ff | 172 | sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); |
3c0ef626 | 173 | if (sock < 0) |
174 | error("socket: %.100s", strerror(errno)); | |
3c0ef626 | 175 | |
176 | /* Bind the socket to an alternative local IP address */ | |
177 | if (options.bind_address == NULL) | |
178 | return sock; | |
179 | ||
180 | memset(&hints, 0, sizeof(hints)); | |
0fff78ff | 181 | hints.ai_family = ai->ai_family; |
182 | hints.ai_socktype = ai->ai_socktype; | |
183 | hints.ai_protocol = ai->ai_protocol; | |
3c0ef626 | 184 | hints.ai_flags = AI_PASSIVE; |
185 | gaierr = getaddrinfo(options.bind_address, "0", &hints, &res); | |
186 | if (gaierr) { | |
187 | error("getaddrinfo: %s: %s", options.bind_address, | |
188 | gai_strerror(gaierr)); | |
189 | close(sock); | |
190 | return -1; | |
191 | } | |
192 | if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { | |
193 | error("bind: %s: %s", options.bind_address, strerror(errno)); | |
194 | close(sock); | |
195 | freeaddrinfo(res); | |
196 | return -1; | |
197 | } | |
198 | freeaddrinfo(res); | |
199 | return sock; | |
200 | } | |
201 | ||
0fff78ff | 202 | static int |
203 | timeout_connect(int sockfd, const struct sockaddr *serv_addr, | |
204 | socklen_t addrlen, int timeout) | |
205 | { | |
206 | fd_set *fdset; | |
207 | struct timeval tv; | |
208 | socklen_t optlen; | |
209 | int fdsetsz, optval, rc, result = -1; | |
210 | ||
211 | if (timeout <= 0) | |
212 | return (connect(sockfd, serv_addr, addrlen)); | |
213 | ||
cdd66111 | 214 | set_nonblock(sockfd); |
0fff78ff | 215 | rc = connect(sockfd, serv_addr, addrlen); |
cdd66111 | 216 | if (rc == 0) { |
217 | unset_nonblock(sockfd); | |
0fff78ff | 218 | return (0); |
cdd66111 | 219 | } |
0fff78ff | 220 | if (errno != EINPROGRESS) |
221 | return (-1); | |
222 | ||
223 | fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask); | |
224 | fdset = (fd_set *)xmalloc(fdsetsz); | |
225 | ||
226 | memset(fdset, 0, fdsetsz); | |
227 | FD_SET(sockfd, fdset); | |
228 | tv.tv_sec = timeout; | |
229 | tv.tv_usec = 0; | |
230 | ||
dec6d9fe | 231 | for (;;) { |
0fff78ff | 232 | rc = select(sockfd + 1, NULL, fdset, NULL, &tv); |
233 | if (rc != -1 || errno != EINTR) | |
234 | break; | |
235 | } | |
236 | ||
dec6d9fe | 237 | switch (rc) { |
0fff78ff | 238 | case 0: |
239 | /* Timed out */ | |
240 | errno = ETIMEDOUT; | |
241 | break; | |
242 | case -1: | |
243 | /* Select error */ | |
cdd66111 | 244 | debug("select: %s", strerror(errno)); |
0fff78ff | 245 | break; |
246 | case 1: | |
247 | /* Completed or failed */ | |
248 | optval = 0; | |
249 | optlen = sizeof(optval); | |
cdd66111 | 250 | if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, |
acc3d05e | 251 | &optlen) == -1) { |
cdd66111 | 252 | debug("getsockopt: %s", strerror(errno)); |
0fff78ff | 253 | break; |
acc3d05e | 254 | } |
0fff78ff | 255 | if (optval != 0) { |
256 | errno = optval; | |
257 | break; | |
258 | } | |
259 | result = 0; | |
cdd66111 | 260 | unset_nonblock(sockfd); |
0fff78ff | 261 | break; |
262 | default: | |
263 | /* Should not occur */ | |
264 | fatal("Bogus return (%d) from select()", rc); | |
265 | } | |
266 | ||
267 | xfree(fdset); | |
268 | return (result); | |
269 | } | |
270 | ||
3c0ef626 | 271 | /* |
272 | * Opens a TCP/IP connection to the remote server on the given host. | |
273 | * The address of the remote host will be returned in hostaddr. | |
f5799ae1 | 274 | * If port is 0, the default port will be used. If needpriv is true, |
3c0ef626 | 275 | * a privileged port will be allocated to make the connection. |
f5799ae1 | 276 | * This requires super-user privileges if needpriv is true. |
3c0ef626 | 277 | * Connection_attempts specifies the maximum number of tries (one per |
278 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
279 | * and %p substituted for host and port, respectively) to use to contact | |
280 | * the daemon. | |
3c0ef626 | 281 | */ |
282 | int | |
283 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, | |
284 | u_short port, int family, int connection_attempts, | |
f5799ae1 | 285 | int needpriv, const char *proxy_command) |
3c0ef626 | 286 | { |
287 | int gaierr; | |
288 | int on = 1; | |
289 | int sock = -1, attempt; | |
290 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
291 | struct addrinfo hints, *ai, *aitop; | |
3c0ef626 | 292 | |
6a9b3198 | 293 | debug2("ssh_connect: needpriv %d", needpriv); |
3c0ef626 | 294 | |
3c0ef626 | 295 | /* If a proxy command is given, connect using it. */ |
296 | if (proxy_command != NULL) | |
f5799ae1 | 297 | return ssh_proxy_connect(host, port, proxy_command); |
3c0ef626 | 298 | |
299 | /* No proxy command. */ | |
300 | ||
301 | memset(&hints, 0, sizeof(hints)); | |
302 | hints.ai_family = family; | |
303 | hints.ai_socktype = SOCK_STREAM; | |
680cee3b | 304 | snprintf(strport, sizeof strport, "%u", port); |
3c0ef626 | 305 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) |
306 | fatal("%s: %.100s: %s", __progname, host, | |
307 | gai_strerror(gaierr)); | |
308 | ||
309 | /* | |
310 | * Try to connect several times. On some machines, the first time | |
311 | * will sometimes fail. In general socket code appears to behave | |
312 | * quite magically on many machines. | |
313 | */ | |
314 | for (attempt = 0; ;) { | |
315 | if (attempt > 0) | |
316 | debug("Trying again..."); | |
317 | ||
318 | /* Loop through addresses for this host, and try each one in | |
319 | sequence until the connection succeeds. */ | |
320 | for (ai = aitop; ai; ai = ai->ai_next) { | |
321 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
322 | continue; | |
323 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
324 | ntop, sizeof(ntop), strport, sizeof(strport), | |
325 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
326 | error("ssh_connect: getnameinfo failed"); | |
327 | continue; | |
328 | } | |
329 | debug("Connecting to %.200s [%.100s] port %s.", | |
330 | host, ntop, strport); | |
331 | ||
332 | /* Create a socket for connecting. */ | |
0fff78ff | 333 | sock = ssh_create_socket(needpriv, ai); |
3c0ef626 | 334 | if (sock < 0) |
335 | /* Any error is already output */ | |
336 | continue; | |
337 | ||
0fff78ff | 338 | if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, |
339 | options.connection_timeout) >= 0) { | |
3c0ef626 | 340 | /* Successful connection. */ |
341 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); | |
3c0ef626 | 342 | break; |
343 | } else { | |
41b2f314 | 344 | debug("connect to address %s port %s: %s", |
345 | ntop, strport, strerror(errno)); | |
3c0ef626 | 346 | /* |
347 | * Close the failed socket; there appear to | |
348 | * be some problems when reusing a socket for | |
349 | * which connect() has already returned an | |
350 | * error. | |
351 | */ | |
3c0ef626 | 352 | close(sock); |
353 | } | |
354 | } | |
355 | if (ai) | |
356 | break; /* Successful connection. */ | |
357 | ||
358 | attempt++; | |
359 | if (attempt >= connection_attempts) | |
360 | break; | |
361 | /* Sleep a moment before retrying. */ | |
362 | sleep(1); | |
363 | } | |
364 | ||
365 | freeaddrinfo(aitop); | |
366 | ||
367 | /* Return failure if we didn't get a successful connection. */ | |
41b2f314 | 368 | if (attempt >= connection_attempts) { |
996d5e62 | 369 | error("ssh: connect to host %s port %s: %s", |
41b2f314 | 370 | host, strport, strerror(errno)); |
996d5e62 | 371 | return (-1); |
41b2f314 | 372 | } |
3c0ef626 | 373 | |
374 | debug("Connection established."); | |
375 | ||
cdd66111 | 376 | /* Set SO_KEEPALIVE if requested. */ |
377 | if (options.tcp_keep_alive && | |
3c0ef626 | 378 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, |
379 | sizeof(on)) < 0) | |
380 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
381 | ||
382 | /* Set the connection. */ | |
383 | packet_set_connection(sock, sock); | |
384 | ||
385 | return 0; | |
386 | } | |
387 | ||
388 | /* | |
389 | * Waits for the server identification string, and sends our own | |
390 | * identification string. | |
391 | */ | |
392 | static void | |
393 | ssh_exchange_identification(void) | |
394 | { | |
395 | char buf[256], remote_version[256]; /* must be same size! */ | |
665a873d | 396 | int remote_major, remote_minor, mismatch; |
3c0ef626 | 397 | int connection_in = packet_get_connection_in(); |
398 | int connection_out = packet_get_connection_out(); | |
399 | int minor1 = PROTOCOL_MINOR_1; | |
665a873d | 400 | u_int i; |
3c0ef626 | 401 | |
665a873d | 402 | /* Read other side's version identification. */ |
3c0ef626 | 403 | for (;;) { |
404 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
665a873d | 405 | size_t len = atomicio(read, connection_in, &buf[i], 1); |
406 | ||
407 | if (len != 1 && errno == EPIPE) | |
3c0ef626 | 408 | fatal("ssh_exchange_identification: Connection closed by remote host"); |
665a873d | 409 | else if (len != 1) |
410 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); | |
3c0ef626 | 411 | if (buf[i] == '\r') { |
412 | buf[i] = '\n'; | |
413 | buf[i + 1] = 0; | |
414 | continue; /**XXX wait for \n */ | |
415 | } | |
416 | if (buf[i] == '\n') { | |
417 | buf[i + 1] = 0; | |
418 | break; | |
419 | } | |
420 | } | |
421 | buf[sizeof(buf) - 1] = 0; | |
422 | if (strncmp(buf, "SSH-", 4) == 0) | |
423 | break; | |
424 | debug("ssh_exchange_identification: %s", buf); | |
425 | } | |
426 | server_version_string = xstrdup(buf); | |
427 | ||
428 | /* | |
429 | * Check that the versions match. In future this might accept | |
430 | * several versions and set appropriate flags to handle them. | |
431 | */ | |
432 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", | |
433 | &remote_major, &remote_minor, remote_version) != 3) | |
434 | fatal("Bad remote protocol version identification: '%.100s'", buf); | |
435 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
e9a17296 | 436 | remote_major, remote_minor, remote_version); |
3c0ef626 | 437 | |
438 | compat_datafellows(remote_version); | |
439 | mismatch = 0; | |
440 | ||
e9a17296 | 441 | switch (remote_major) { |
3c0ef626 | 442 | case 1: |
443 | if (remote_minor == 99 && | |
444 | (options.protocol & SSH_PROTO_2) && | |
445 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
446 | enable_compat20(); | |
447 | break; | |
448 | } | |
449 | if (!(options.protocol & SSH_PROTO_1)) { | |
450 | mismatch = 1; | |
451 | break; | |
452 | } | |
453 | if (remote_minor < 3) { | |
454 | fatal("Remote machine has too old SSH software version."); | |
455 | } else if (remote_minor == 3 || remote_minor == 4) { | |
456 | /* We speak 1.3, too. */ | |
457 | enable_compat13(); | |
458 | minor1 = 3; | |
459 | if (options.forward_agent) { | |
0fff78ff | 460 | logit("Agent forwarding disabled for protocol 1.3"); |
3c0ef626 | 461 | options.forward_agent = 0; |
462 | } | |
463 | } | |
464 | break; | |
465 | case 2: | |
466 | if (options.protocol & SSH_PROTO_2) { | |
467 | enable_compat20(); | |
468 | break; | |
469 | } | |
470 | /* FALLTHROUGH */ | |
471 | default: | |
472 | mismatch = 1; | |
473 | break; | |
474 | } | |
475 | if (mismatch) | |
476 | fatal("Protocol major versions differ: %d vs. %d", | |
477 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, | |
478 | remote_major); | |
479 | /* Send our own protocol version identification. */ | |
480 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
481 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, | |
482 | compat20 ? PROTOCOL_MINOR_2 : minor1, | |
483 | SSH_VERSION); | |
0fff78ff | 484 | if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf)) |
3c0ef626 | 485 | fatal("write: %.100s", strerror(errno)); |
486 | client_version_string = xstrdup(buf); | |
487 | chop(client_version_string); | |
488 | chop(server_version_string); | |
489 | debug("Local version string %.100s", client_version_string); | |
490 | } | |
491 | ||
492 | /* defaults to 'no' */ | |
493 | static int | |
494 | confirm(const char *prompt) | |
495 | { | |
e9a17296 | 496 | const char *msg, *again = "Please type 'yes' or 'no': "; |
497 | char *p; | |
498 | int ret = -1; | |
3c0ef626 | 499 | |
500 | if (options.batch_mode) | |
501 | return 0; | |
e9a17296 | 502 | for (msg = prompt;;msg = again) { |
503 | p = read_passphrase(msg, RP_ECHO); | |
504 | if (p == NULL || | |
505 | (p[0] == '\0') || (p[0] == '\n') || | |
506 | strncasecmp(p, "no", 2) == 0) | |
507 | ret = 0; | |
41b2f314 | 508 | if (p && strncasecmp(p, "yes", 3) == 0) |
e9a17296 | 509 | ret = 1; |
510 | if (p) | |
511 | xfree(p); | |
512 | if (ret != -1) | |
513 | return ret; | |
3c0ef626 | 514 | } |
515 | } | |
516 | ||
517 | /* | |
518 | * check whether the supplied host key is valid, return -1 if the key | |
519 | * is not valid. the user_hostfile will not be updated if 'readonly' is true. | |
520 | */ | |
3c0ef626 | 521 | static int |
522 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, | |
523 | int readonly, const char *user_hostfile, const char *system_hostfile) | |
524 | { | |
525 | Key *file_key; | |
cdd66111 | 526 | const char *type = key_type(host_key); |
3c0ef626 | 527 | char *ip = NULL; |
528 | char hostline[1000], *hostp, *fp; | |
529 | HostStatus host_status; | |
530 | HostStatus ip_status; | |
996d5e62 | 531 | int r, local = 0, host_ip_differ = 0; |
3c0ef626 | 532 | int salen; |
533 | char ntop[NI_MAXHOST]; | |
e9a17296 | 534 | char msg[1024]; |
0fff78ff | 535 | int len, host_line, ip_line; |
3c0ef626 | 536 | const char *host_file = NULL, *ip_file = NULL; |
537 | ||
538 | /* | |
539 | * Force accepting of the host key for loopback/localhost. The | |
540 | * problem is that if the home directory is NFS-mounted to multiple | |
541 | * machines, localhost will refer to a different machine in each of | |
542 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
543 | * essentially disables host authentication for localhost; however, | |
544 | * this is probably not a real problem. | |
545 | */ | |
546 | /** hostaddr == 0! */ | |
547 | switch (hostaddr->sa_family) { | |
548 | case AF_INET: | |
549 | local = (ntohl(((struct sockaddr_in *)hostaddr)-> | |
665a873d | 550 | sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; |
3c0ef626 | 551 | salen = sizeof(struct sockaddr_in); |
552 | break; | |
553 | case AF_INET6: | |
554 | local = IN6_IS_ADDR_LOOPBACK( | |
555 | &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
556 | salen = sizeof(struct sockaddr_in6); | |
557 | break; | |
558 | default: | |
559 | local = 0; | |
560 | salen = sizeof(struct sockaddr_storage); | |
561 | break; | |
562 | } | |
563 | if (options.no_host_authentication_for_localhost == 1 && local && | |
564 | options.host_key_alias == NULL) { | |
565 | debug("Forcing accepting of host key for " | |
566 | "loopback/localhost."); | |
567 | return 0; | |
568 | } | |
569 | ||
570 | /* | |
571 | * We don't have the remote ip-address for connections | |
572 | * using a proxy command | |
573 | */ | |
574 | if (options.proxy_command == NULL) { | |
575 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), | |
576 | NULL, 0, NI_NUMERICHOST) != 0) | |
577 | fatal("check_host_key: getnameinfo failed"); | |
578 | ip = xstrdup(ntop); | |
579 | } else { | |
580 | ip = xstrdup("<no hostip for proxy command>"); | |
581 | } | |
582 | /* | |
583 | * Turn off check_host_ip if the connection is to localhost, via proxy | |
584 | * command or if we don't have a hostname to compare with | |
585 | */ | |
586 | if (options.check_host_ip && | |
587 | (local || strcmp(host, ip) == 0 || options.proxy_command != NULL)) | |
588 | options.check_host_ip = 0; | |
589 | ||
590 | /* | |
591 | * Allow the user to record the key under a different name. This is | |
592 | * useful for ssh tunneling over forwarded connections or if you run | |
593 | * multiple sshd's on different ports on the same machine. | |
594 | */ | |
595 | if (options.host_key_alias != NULL) { | |
596 | host = options.host_key_alias; | |
597 | debug("using hostkeyalias: %s", host); | |
598 | } | |
599 | ||
600 | /* | |
601 | * Store the host key from the known host file in here so that we can | |
602 | * compare it with the key for the IP address. | |
603 | */ | |
604 | file_key = key_new(host_key->type); | |
605 | ||
606 | /* | |
607 | * Check if the host key is present in the user\'s list of known | |
608 | * hosts or in the systemwide list. | |
609 | */ | |
610 | host_file = user_hostfile; | |
611 | host_status = check_host_in_hostfile(host_file, host, host_key, | |
e9a17296 | 612 | file_key, &host_line); |
3c0ef626 | 613 | if (host_status == HOST_NEW) { |
614 | host_file = system_hostfile; | |
615 | host_status = check_host_in_hostfile(host_file, host, host_key, | |
616 | file_key, &host_line); | |
617 | } | |
618 | /* | |
619 | * Also perform check for the ip address, skip the check if we are | |
620 | * localhost or the hostname was an ip address to begin with | |
621 | */ | |
622 | if (options.check_host_ip) { | |
623 | Key *ip_key = key_new(host_key->type); | |
624 | ||
625 | ip_file = user_hostfile; | |
626 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, | |
627 | ip_key, &ip_line); | |
628 | if (ip_status == HOST_NEW) { | |
629 | ip_file = system_hostfile; | |
630 | ip_status = check_host_in_hostfile(ip_file, ip, | |
631 | host_key, ip_key, &ip_line); | |
632 | } | |
633 | if (host_status == HOST_CHANGED && | |
634 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) | |
635 | host_ip_differ = 1; | |
636 | ||
637 | key_free(ip_key); | |
638 | } else | |
639 | ip_status = host_status; | |
640 | ||
641 | key_free(file_key); | |
642 | ||
643 | switch (host_status) { | |
644 | case HOST_OK: | |
645 | /* The host is known and the key matches. */ | |
646 | debug("Host '%.200s' is known and matches the %s host key.", | |
647 | host, type); | |
648 | debug("Found key in %s:%d", host_file, host_line); | |
649 | if (options.check_host_ip && ip_status == HOST_NEW) { | |
650 | if (readonly) | |
0fff78ff | 651 | logit("%s host key for IP address " |
3c0ef626 | 652 | "'%.128s' not in list of known hosts.", |
653 | type, ip); | |
654 | else if (!add_host_to_hostfile(user_hostfile, ip, | |
996d5e62 | 655 | host_key, options.hash_known_hosts)) |
0fff78ff | 656 | logit("Failed to add the %s host key for IP " |
3c0ef626 | 657 | "address '%.128s' to the list of known " |
658 | "hosts (%.30s).", type, ip, user_hostfile); | |
659 | else | |
0fff78ff | 660 | logit("Warning: Permanently added the %s host " |
3c0ef626 | 661 | "key for IP address '%.128s' to the list " |
662 | "of known hosts.", type, ip); | |
663 | } | |
664 | break; | |
665 | case HOST_NEW: | |
666 | if (readonly) | |
667 | goto fail; | |
668 | /* The host is new. */ | |
669 | if (options.strict_host_key_checking == 1) { | |
670 | /* | |
671 | * User has requested strict host key checking. We | |
672 | * will not add the host key automatically. The only | |
673 | * alternative left is to abort. | |
674 | */ | |
675 | error("No %s host key is known for %.200s and you " | |
676 | "have requested strict checking.", type, host); | |
677 | goto fail; | |
678 | } else if (options.strict_host_key_checking == 2) { | |
0fff78ff | 679 | char msg1[1024], msg2[1024]; |
680 | ||
681 | if (show_other_keys(host, host_key)) | |
682 | snprintf(msg1, sizeof(msg1), | |
665a873d | 683 | "\nbut keys of different type are already" |
684 | " known for this host."); | |
0fff78ff | 685 | else |
686 | snprintf(msg1, sizeof(msg1), "."); | |
3c0ef626 | 687 | /* The default */ |
3c0ef626 | 688 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
0fff78ff | 689 | msg2[0] = '\0'; |
0fff78ff | 690 | if (options.verify_host_key_dns) { |
cdd66111 | 691 | if (matching_host_key_dns) |
0fff78ff | 692 | snprintf(msg2, sizeof(msg2), |
693 | "Matching host key fingerprint" | |
694 | " found in DNS.\n"); | |
695 | else | |
696 | snprintf(msg2, sizeof(msg2), | |
697 | "No matching host key fingerprint" | |
698 | " found in DNS.\n"); | |
699 | } | |
e9a17296 | 700 | snprintf(msg, sizeof(msg), |
3c0ef626 | 701 | "The authenticity of host '%.200s (%s)' can't be " |
41b2f314 | 702 | "established%s\n" |
0fff78ff | 703 | "%s key fingerprint is %s.\n%s" |
3c0ef626 | 704 | "Are you sure you want to continue connecting " |
41b2f314 | 705 | "(yes/no)? ", |
0fff78ff | 706 | host, ip, msg1, type, fp, msg2); |
3c0ef626 | 707 | xfree(fp); |
e9a17296 | 708 | if (!confirm(msg)) |
3c0ef626 | 709 | goto fail; |
3c0ef626 | 710 | } |
3c0ef626 | 711 | /* |
712 | * If not in strict mode, add the key automatically to the | |
713 | * local known_hosts file. | |
714 | */ | |
996d5e62 | 715 | if (options.check_host_ip && ip_status == HOST_NEW) { |
716 | snprintf(hostline, sizeof(hostline), "%s,%s", | |
717 | host, ip); | |
718 | hostp = hostline; | |
719 | if (options.hash_known_hosts) { | |
720 | /* Add hash of host and IP separately */ | |
721 | r = add_host_to_hostfile(user_hostfile, host, | |
722 | host_key, options.hash_known_hosts) && | |
723 | add_host_to_hostfile(user_hostfile, ip, | |
724 | host_key, options.hash_known_hosts); | |
725 | } else { | |
726 | /* Add unhashed "host,ip" */ | |
727 | r = add_host_to_hostfile(user_hostfile, | |
728 | hostline, host_key, | |
729 | options.hash_known_hosts); | |
730 | } | |
731 | } else { | |
732 | r = add_host_to_hostfile(user_hostfile, host, host_key, | |
733 | options.hash_known_hosts); | |
734 | hostp = host; | |
735 | } | |
736 | ||
737 | if (!r) | |
0fff78ff | 738 | logit("Failed to add the host to the list of known " |
3c0ef626 | 739 | "hosts (%.500s).", user_hostfile); |
740 | else | |
0fff78ff | 741 | logit("Warning: Permanently added '%.200s' (%s) to the " |
3c0ef626 | 742 | "list of known hosts.", hostp, type); |
743 | break; | |
744 | case HOST_CHANGED: | |
745 | if (options.check_host_ip && host_ip_differ) { | |
c9f39d2c | 746 | char *key_msg; |
3c0ef626 | 747 | if (ip_status == HOST_NEW) |
c9f39d2c | 748 | key_msg = "is unknown"; |
3c0ef626 | 749 | else if (ip_status == HOST_OK) |
c9f39d2c | 750 | key_msg = "is unchanged"; |
3c0ef626 | 751 | else |
c9f39d2c | 752 | key_msg = "has a different value"; |
3c0ef626 | 753 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
754 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
755 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
756 | error("The %s host key for %s has changed,", type, host); | |
757 | error("and the key for the according IP address %s", ip); | |
c9f39d2c | 758 | error("%s. This could either mean that", key_msg); |
3c0ef626 | 759 | error("DNS SPOOFING is happening or the IP address for the host"); |
760 | error("and its host key have changed at the same time."); | |
761 | if (ip_status != HOST_NEW) | |
762 | error("Offending key for IP in %s:%d", ip_file, ip_line); | |
763 | } | |
764 | /* The host key has changed. */ | |
cdd66111 | 765 | warn_changed_key(host_key); |
3c0ef626 | 766 | error("Add correct host key in %.100s to get rid of this message.", |
767 | user_hostfile); | |
768 | error("Offending key in %s:%d", host_file, host_line); | |
3c0ef626 | 769 | |
770 | /* | |
771 | * If strict host key checking is in use, the user will have | |
772 | * to edit the key manually and we can only abort. | |
773 | */ | |
774 | if (options.strict_host_key_checking) { | |
775 | error("%s host key for %.200s has changed and you have " | |
776 | "requested strict checking.", type, host); | |
777 | goto fail; | |
778 | } | |
779 | ||
780 | /* | |
781 | * If strict host key checking has not been requested, allow | |
0fff78ff | 782 | * the connection but without MITM-able authentication or |
3c0ef626 | 783 | * agent forwarding. |
784 | */ | |
785 | if (options.password_authentication) { | |
786 | error("Password authentication is disabled to avoid " | |
787 | "man-in-the-middle attacks."); | |
788 | options.password_authentication = 0; | |
789 | } | |
0fff78ff | 790 | if (options.kbd_interactive_authentication) { |
791 | error("Keyboard-interactive authentication is disabled" | |
792 | " to avoid man-in-the-middle attacks."); | |
793 | options.kbd_interactive_authentication = 0; | |
794 | options.challenge_response_authentication = 0; | |
795 | } | |
796 | if (options.challenge_response_authentication) { | |
797 | error("Challenge/response authentication is disabled" | |
798 | " to avoid man-in-the-middle attacks."); | |
799 | options.challenge_response_authentication = 0; | |
800 | } | |
3c0ef626 | 801 | if (options.forward_agent) { |
802 | error("Agent forwarding is disabled to avoid " | |
803 | "man-in-the-middle attacks."); | |
804 | options.forward_agent = 0; | |
805 | } | |
806 | if (options.forward_x11) { | |
807 | error("X11 forwarding is disabled to avoid " | |
808 | "man-in-the-middle attacks."); | |
809 | options.forward_x11 = 0; | |
810 | } | |
811 | if (options.num_local_forwards > 0 || | |
812 | options.num_remote_forwards > 0) { | |
813 | error("Port forwarding is disabled to avoid " | |
814 | "man-in-the-middle attacks."); | |
815 | options.num_local_forwards = | |
e9a17296 | 816 | options.num_remote_forwards = 0; |
3c0ef626 | 817 | } |
818 | /* | |
819 | * XXX Should permit the user to change to use the new id. | |
820 | * This could be done by converting the host key to an | |
821 | * identifying sentence, tell that the host identifies itself | |
822 | * by that sentence, and ask the user if he/she whishes to | |
823 | * accept the authentication. | |
824 | */ | |
825 | break; | |
41b2f314 | 826 | case HOST_FOUND: |
827 | fatal("internal error"); | |
828 | break; | |
3c0ef626 | 829 | } |
830 | ||
831 | if (options.check_host_ip && host_status != HOST_CHANGED && | |
832 | ip_status == HOST_CHANGED) { | |
e9a17296 | 833 | snprintf(msg, sizeof(msg), |
834 | "Warning: the %s host key for '%.200s' " | |
835 | "differs from the key for the IP address '%.128s'" | |
836 | "\nOffending key for IP in %s:%d", | |
837 | type, host, ip, ip_file, ip_line); | |
838 | if (host_status == HOST_OK) { | |
839 | len = strlen(msg); | |
840 | snprintf(msg + len, sizeof(msg) - len, | |
841 | "\nMatching host key in %s:%d", | |
f5799ae1 | 842 | host_file, host_line); |
e9a17296 | 843 | } |
3c0ef626 | 844 | if (options.strict_host_key_checking == 1) { |
0fff78ff | 845 | logit("%s", msg); |
3c0ef626 | 846 | error("Exiting, you have requested strict checking."); |
847 | goto fail; | |
848 | } else if (options.strict_host_key_checking == 2) { | |
e9a17296 | 849 | strlcat(msg, "\nAre you sure you want " |
850 | "to continue connecting (yes/no)? ", sizeof(msg)); | |
851 | if (!confirm(msg)) | |
3c0ef626 | 852 | goto fail; |
e9a17296 | 853 | } else { |
0fff78ff | 854 | logit("%s", msg); |
3c0ef626 | 855 | } |
856 | } | |
857 | ||
858 | xfree(ip); | |
859 | return 0; | |
860 | ||
861 | fail: | |
862 | xfree(ip); | |
863 | return -1; | |
864 | } | |
865 | ||
0fff78ff | 866 | /* returns 0 if key verifies or -1 if key does NOT verify */ |
3c0ef626 | 867 | int |
868 | verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) | |
869 | { | |
870 | struct stat st; | |
cdd66111 | 871 | int flags = 0; |
12408a1b | 872 | |
cdd66111 | 873 | if (options.verify_host_key_dns && |
874 | verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) { | |
875 | ||
876 | if (flags & DNS_VERIFY_FOUND) { | |
877 | ||
878 | if (options.verify_host_key_dns == 1 && | |
879 | flags & DNS_VERIFY_MATCH && | |
880 | flags & DNS_VERIFY_SECURE) | |
881 | return 0; | |
882 | ||
883 | if (flags & DNS_VERIFY_MATCH) { | |
884 | matching_host_key_dns = 1; | |
885 | } else { | |
886 | warn_changed_key(host_key); | |
887 | error("Update the SSHFP RR in DNS with the new " | |
888 | "host key to get rid of this message."); | |
889 | } | |
0fff78ff | 890 | } |
891 | } | |
0fff78ff | 892 | |
3c0ef626 | 893 | /* return ok if the key can be found in an old keyfile */ |
894 | if (stat(options.system_hostfile2, &st) == 0 || | |
895 | stat(options.user_hostfile2, &st) == 0) { | |
896 | if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1, | |
897 | options.user_hostfile2, options.system_hostfile2) == 0) | |
898 | return 0; | |
899 | } | |
900 | return check_host_key(host, hostaddr, host_key, /*readonly*/ 0, | |
901 | options.user_hostfile, options.system_hostfile); | |
902 | } | |
903 | ||
904 | /* | |
905 | * Starts a dialog with the server, and authenticates the current user on the | |
906 | * server. This does not need any extra privileges. The basic connection | |
907 | * to the server must already have been established before this is called. | |
908 | * If login fails, this function prints an error and never returns. | |
909 | * This function does not require super-user privileges. | |
910 | */ | |
911 | void | |
f5799ae1 | 912 | ssh_login(Sensitive *sensitive, const char *orighost, |
3c0ef626 | 913 | struct sockaddr *hostaddr, struct passwd *pw) |
914 | { | |
915 | char *host, *cp; | |
916 | char *server_user, *local_user; | |
917 | ||
918 | local_user = xstrdup(pw->pw_name); | |
919 | server_user = options.user ? options.user : local_user; | |
920 | ||
921 | /* Convert the user-supplied hostname into all lowercase. */ | |
922 | host = xstrdup(orighost); | |
923 | for (cp = host; *cp; cp++) | |
924 | if (isupper(*cp)) | |
925 | *cp = tolower(*cp); | |
926 | ||
927 | /* Exchange protocol version identification strings with the server. */ | |
928 | ssh_exchange_identification(); | |
929 | ||
930 | /* Put the connection into non-blocking mode. */ | |
931 | packet_set_nonblocking(); | |
932 | ||
933 | /* key exchange */ | |
934 | /* authenticate user */ | |
935 | if (compat20) { | |
936 | ssh_kex2(host, hostaddr); | |
f5799ae1 | 937 | ssh_userauth2(local_user, server_user, host, sensitive); |
3c0ef626 | 938 | } else { |
939 | ssh_kex(host, hostaddr); | |
f5799ae1 | 940 | ssh_userauth1(local_user, server_user, host, sensitive); |
3c0ef626 | 941 | } |
942 | } | |
943 | ||
944 | void | |
945 | ssh_put_password(char *password) | |
946 | { | |
947 | int size; | |
948 | char *padded; | |
949 | ||
950 | if (datafellows & SSH_BUG_PASSWORDPAD) { | |
951 | packet_put_cstring(password); | |
952 | return; | |
953 | } | |
954 | size = roundup(strlen(password) + 1, 32); | |
955 | padded = xmalloc(size); | |
956 | memset(padded, 0, size); | |
957 | strlcpy(padded, password, size); | |
958 | packet_put_string(padded, size); | |
959 | memset(padded, 0, size); | |
960 | xfree(padded); | |
961 | } | |
41b2f314 | 962 | |
963 | static int | |
964 | show_key_from_file(const char *file, const char *host, int keytype) | |
965 | { | |
966 | Key *found; | |
967 | char *fp; | |
968 | int line, ret; | |
969 | ||
970 | found = key_new(keytype); | |
971 | if ((ret = lookup_key_in_hostfile_by_type(file, host, | |
972 | keytype, found, &line))) { | |
973 | fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX); | |
0fff78ff | 974 | logit("WARNING: %s key found for host %s\n" |
41b2f314 | 975 | "in %s:%d\n" |
976 | "%s key fingerprint %s.", | |
977 | key_type(found), host, file, line, | |
978 | key_type(found), fp); | |
979 | xfree(fp); | |
980 | } | |
981 | key_free(found); | |
982 | return (ret); | |
983 | } | |
984 | ||
985 | /* print all known host keys for a given host, but skip keys of given type */ | |
986 | static int | |
987 | show_other_keys(const char *host, Key *key) | |
988 | { | |
989 | int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1}; | |
990 | int i, found = 0; | |
991 | ||
992 | for (i = 0; type[i] != -1; i++) { | |
993 | if (type[i] == key->type) | |
994 | continue; | |
995 | if (type[i] != KEY_RSA1 && | |
996 | show_key_from_file(options.user_hostfile2, host, type[i])) { | |
997 | found = 1; | |
998 | continue; | |
999 | } | |
1000 | if (type[i] != KEY_RSA1 && | |
1001 | show_key_from_file(options.system_hostfile2, host, type[i])) { | |
1002 | found = 1; | |
1003 | continue; | |
1004 | } | |
1005 | if (show_key_from_file(options.user_hostfile, host, type[i])) { | |
1006 | found = 1; | |
1007 | continue; | |
1008 | } | |
1009 | if (show_key_from_file(options.system_hostfile, host, type[i])) { | |
1010 | found = 1; | |
1011 | continue; | |
1012 | } | |
1013 | debug2("no key of type %d for host %s", type[i], host); | |
1014 | } | |
1015 | return (found); | |
1016 | } | |
cdd66111 | 1017 | |
1018 | static void | |
1019 | warn_changed_key(Key *host_key) | |
1020 | { | |
1021 | char *fp; | |
1022 | const char *type = key_type(host_key); | |
1023 | ||
1024 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); | |
1025 | ||
1026 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1027 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); | |
1028 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1029 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
1030 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
1031 | error("It is also possible that the %s host key has just been changed.", type); | |
1032 | error("The fingerprint for the %s key sent by the remote host is\n%s.", | |
1033 | type, fp); | |
1034 | error("Please contact your system administrator."); | |
1035 | ||
1036 | xfree(fp); | |
1037 | } |