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8efc0c15 | 1 | /* |
5260325f | 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 | */ | |
8efc0c15 | 9 | |
10 | #include "includes.h" | |
a306f2dd | 11 | RCSID("$OpenBSD: sshconnect.c,v 1.71 2000/04/26 21:28:33 markus Exp $"); |
8efc0c15 | 12 | |
8ce64345 | 13 | #include <openssl/bn.h> |
a306f2dd | 14 | #include <openssl/dsa.h> |
15 | #include <openssl/rsa.h> | |
16 | ||
8efc0c15 | 17 | #include "xmalloc.h" |
18 | #include "rsa.h" | |
19 | #include "ssh.h" | |
8ce64345 | 20 | #include "buffer.h" |
8efc0c15 | 21 | #include "packet.h" |
8efc0c15 | 22 | #include "uidswap.h" |
23 | #include "compat.h" | |
6fa724bc | 24 | #include "readconf.h" |
4fe2af09 | 25 | #include "key.h" |
a306f2dd | 26 | #include "sshconnect.h" |
4fe2af09 | 27 | #include "hostfile.h" |
8efc0c15 | 28 | |
a306f2dd | 29 | char *client_version_string = NULL; |
30 | char *server_version_string = NULL; | |
8ce64345 | 31 | |
57112b5a | 32 | extern Options options; |
48e671d5 | 33 | extern char *__progname; |
57112b5a | 34 | |
5260325f | 35 | /* |
36 | * Connect to the given ssh server using a proxy command. | |
37 | */ | |
8efc0c15 | 38 | int |
57112b5a | 39 | ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid, |
8efc0c15 | 40 | const char *proxy_command) |
41 | { | |
5260325f | 42 | Buffer command; |
43 | const char *cp; | |
44 | char *command_string; | |
45 | int pin[2], pout[2]; | |
9da5c3c9 | 46 | pid_t pid; |
48e671d5 | 47 | char strport[NI_MAXSERV]; |
5260325f | 48 | |
49 | /* Convert the port number into a string. */ | |
48e671d5 | 50 | snprintf(strport, sizeof strport, "%hu", port); |
5260325f | 51 | |
52 | /* Build the final command string in the buffer by making the | |
53 | appropriate substitutions to the given proxy command. */ | |
54 | buffer_init(&command); | |
55 | for (cp = proxy_command; *cp; cp++) { | |
56 | if (cp[0] == '%' && cp[1] == '%') { | |
57 | buffer_append(&command, "%", 1); | |
58 | cp++; | |
59 | continue; | |
60 | } | |
61 | if (cp[0] == '%' && cp[1] == 'h') { | |
62 | buffer_append(&command, host, strlen(host)); | |
63 | cp++; | |
64 | continue; | |
65 | } | |
66 | if (cp[0] == '%' && cp[1] == 'p') { | |
48e671d5 | 67 | buffer_append(&command, strport, strlen(strport)); |
5260325f | 68 | cp++; |
69 | continue; | |
70 | } | |
71 | buffer_append(&command, cp, 1); | |
8efc0c15 | 72 | } |
5260325f | 73 | buffer_append(&command, "\0", 1); |
74 | ||
75 | /* Get the final command string. */ | |
76 | command_string = buffer_ptr(&command); | |
77 | ||
78 | /* Create pipes for communicating with the proxy. */ | |
79 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
80 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
81 | strerror(errno)); | |
82 | ||
83 | debug("Executing proxy command: %.500s", command_string); | |
84 | ||
85 | /* Fork and execute the proxy command. */ | |
86 | if ((pid = fork()) == 0) { | |
87 | char *argv[10]; | |
88 | ||
89 | /* Child. Permanently give up superuser privileges. */ | |
90 | permanently_set_uid(original_real_uid); | |
91 | ||
92 | /* Redirect stdin and stdout. */ | |
93 | close(pin[1]); | |
94 | if (pin[0] != 0) { | |
95 | if (dup2(pin[0], 0) < 0) | |
96 | perror("dup2 stdin"); | |
97 | close(pin[0]); | |
98 | } | |
99 | close(pout[0]); | |
100 | if (dup2(pout[1], 1) < 0) | |
101 | perror("dup2 stdout"); | |
102 | /* Cannot be 1 because pin allocated two descriptors. */ | |
103 | close(pout[1]); | |
104 | ||
105 | /* Stderr is left as it is so that error messages get | |
106 | printed on the user's terminal. */ | |
107 | argv[0] = "/bin/sh"; | |
108 | argv[1] = "-c"; | |
109 | argv[2] = command_string; | |
110 | argv[3] = NULL; | |
111 | ||
112 | /* Execute the proxy command. Note that we gave up any | |
113 | extra privileges above. */ | |
114 | execv("/bin/sh", argv); | |
115 | perror("/bin/sh"); | |
116 | exit(1); | |
8efc0c15 | 117 | } |
5260325f | 118 | /* Parent. */ |
119 | if (pid < 0) | |
120 | fatal("fork failed: %.100s", strerror(errno)); | |
121 | ||
122 | /* Close child side of the descriptors. */ | |
123 | close(pin[0]); | |
124 | close(pout[1]); | |
125 | ||
126 | /* Free the command name. */ | |
127 | buffer_free(&command); | |
128 | ||
129 | /* Set the connection file descriptors. */ | |
130 | packet_set_connection(pout[0], pin[1]); | |
8efc0c15 | 131 | |
5260325f | 132 | return 1; |
133 | } | |
8efc0c15 | 134 | |
5260325f | 135 | /* |
136 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
137 | */ | |
138 | int | |
48e671d5 | 139 | ssh_create_socket(uid_t original_real_uid, int privileged, int family) |
8efc0c15 | 140 | { |
5260325f | 141 | int sock; |
142 | ||
aa3378df | 143 | /* |
144 | * If we are running as root and want to connect to a privileged | |
145 | * port, bind our own socket to a privileged port. | |
146 | */ | |
5260325f | 147 | if (privileged) { |
148 | int p = IPPORT_RESERVED - 1; | |
48e671d5 | 149 | sock = rresvport_af(&p, family); |
5260325f | 150 | if (sock < 0) |
c8d54615 | 151 | error("rresvport: af=%d %.100s", family, strerror(errno)); |
152 | else | |
153 | debug("Allocated local port %d.", p); | |
5260325f | 154 | } else { |
95f1eccc | 155 | /* |
156 | * Just create an ordinary socket on arbitrary port. We use | |
157 | * the user's uid to create the socket. | |
158 | */ | |
5260325f | 159 | temporarily_use_uid(original_real_uid); |
48e671d5 | 160 | sock = socket(family, SOCK_STREAM, 0); |
5260325f | 161 | if (sock < 0) |
48e671d5 | 162 | error("socket: %.100s", strerror(errno)); |
5260325f | 163 | restore_uid(); |
164 | } | |
165 | return sock; | |
8efc0c15 | 166 | } |
167 | ||
5260325f | 168 | /* |
48e671d5 | 169 | * Opens a TCP/IP connection to the remote server on the given host. |
170 | * The address of the remote host will be returned in hostaddr. | |
171 | * If port is 0, the default port will be used. If anonymous is zero, | |
5260325f | 172 | * a privileged port will be allocated to make the connection. |
173 | * This requires super-user privileges if anonymous is false. | |
174 | * Connection_attempts specifies the maximum number of tries (one per | |
175 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
176 | * and %p substituted for host and port, respectively) to use to contact | |
177 | * the daemon. | |
178 | */ | |
179 | int | |
48e671d5 | 180 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, |
57112b5a | 181 | u_short port, int connection_attempts, |
5260325f | 182 | int anonymous, uid_t original_real_uid, |
183 | const char *proxy_command) | |
8efc0c15 | 184 | { |
48e671d5 | 185 | int sock = -1, attempt; |
5260325f | 186 | struct servent *sp; |
48e671d5 | 187 | struct addrinfo hints, *ai, *aitop; |
188 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
189 | int gaierr; | |
5260325f | 190 | struct linger linger; |
191 | ||
192 | debug("ssh_connect: getuid %d geteuid %d anon %d", | |
193 | (int) getuid(), (int) geteuid(), anonymous); | |
194 | ||
195 | /* Get default port if port has not been set. */ | |
196 | if (port == 0) { | |
197 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
198 | if (sp) | |
199 | port = ntohs(sp->s_port); | |
200 | else | |
201 | port = SSH_DEFAULT_PORT; | |
8efc0c15 | 202 | } |
5260325f | 203 | /* If a proxy command is given, connect using it. */ |
204 | if (proxy_command != NULL) | |
205 | return ssh_proxy_connect(host, port, original_real_uid, proxy_command); | |
206 | ||
207 | /* No proxy command. */ | |
208 | ||
48e671d5 | 209 | memset(&hints, 0, sizeof(hints)); |
210 | hints.ai_family = IPv4or6; | |
211 | hints.ai_socktype = SOCK_STREAM; | |
212 | snprintf(strport, sizeof strport, "%d", port); | |
213 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) | |
214 | fatal("%s: %.100s: %s", __progname, host, | |
215 | gai_strerror(gaierr)); | |
5260325f | 216 | |
95f1eccc | 217 | /* |
218 | * Try to connect several times. On some machines, the first time | |
219 | * will sometimes fail. In general socket code appears to behave | |
220 | * quite magically on many machines. | |
221 | */ | |
5260325f | 222 | for (attempt = 0; attempt < connection_attempts; attempt++) { |
223 | if (attempt > 0) | |
224 | debug("Trying again..."); | |
225 | ||
48e671d5 | 226 | /* Loop through addresses for this host, and try each one in |
6ae2364d | 227 | sequence until the connection succeeds. */ |
48e671d5 | 228 | for (ai = aitop; ai; ai = ai->ai_next) { |
229 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
230 | continue; | |
231 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
232 | ntop, sizeof(ntop), strport, sizeof(strport), | |
233 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
234 | error("ssh_connect: getnameinfo failed"); | |
235 | continue; | |
236 | } | |
237 | debug("Connecting to %.200s [%.100s] port %s.", | |
238 | host, ntop, strport); | |
239 | ||
240 | /* Create a socket for connecting. */ | |
6ae2364d | 241 | sock = ssh_create_socket(original_real_uid, |
48e671d5 | 242 | !anonymous && geteuid() == 0 && port < IPPORT_RESERVED, |
243 | ai->ai_family); | |
244 | if (sock < 0) | |
245 | continue; | |
246 | ||
247 | /* Connect to the host. We use the user's uid in the | |
248 | * hope that it will help with tcp_wrappers showing | |
249 | * the remote uid as root. | |
aa3378df | 250 | */ |
5260325f | 251 | temporarily_use_uid(original_real_uid); |
48e671d5 | 252 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { |
253 | /* Successful connection. */ | |
254 | memcpy(hostaddr, ai->ai_addr, sizeof(*(ai->ai_addr))); | |
5260325f | 255 | restore_uid(); |
256 | break; | |
48e671d5 | 257 | } else { |
5260325f | 258 | debug("connect: %.100s", strerror(errno)); |
259 | restore_uid(); | |
aa3378df | 260 | /* |
261 | * Close the failed socket; there appear to | |
262 | * be some problems when reusing a socket for | |
263 | * which connect() has already returned an | |
264 | * error. | |
265 | */ | |
5260325f | 266 | shutdown(sock, SHUT_RDWR); |
267 | close(sock); | |
268 | } | |
8efc0c15 | 269 | } |
48e671d5 | 270 | if (ai) |
271 | break; /* Successful connection. */ | |
8efc0c15 | 272 | |
5260325f | 273 | /* Sleep a moment before retrying. */ |
274 | sleep(1); | |
275 | } | |
48e671d5 | 276 | |
277 | freeaddrinfo(aitop); | |
278 | ||
5260325f | 279 | /* Return failure if we didn't get a successful connection. */ |
280 | if (attempt >= connection_attempts) | |
281 | return 0; | |
8efc0c15 | 282 | |
5260325f | 283 | debug("Connection established."); |
8efc0c15 | 284 | |
aa3378df | 285 | /* |
286 | * Set socket options. We would like the socket to disappear as soon | |
287 | * as it has been closed for whatever reason. | |
288 | */ | |
289 | /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 290 | linger.l_onoff = 1; |
291 | linger.l_linger = 5; | |
292 | setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
8efc0c15 | 293 | |
5260325f | 294 | /* Set the connection. */ |
295 | packet_set_connection(sock, sock); | |
8efc0c15 | 296 | |
5260325f | 297 | return 1; |
8efc0c15 | 298 | } |
299 | ||
8ce64345 | 300 | char * |
301 | chop(char *s) | |
302 | { | |
303 | char *t = s; | |
304 | while (*t) { | |
305 | if(*t == '\n' || *t == '\r') { | |
306 | *t = '\0'; | |
307 | return s; | |
308 | } | |
309 | t++; | |
310 | } | |
311 | return s; | |
312 | ||
313 | } | |
314 | ||
5260325f | 315 | /* |
316 | * Waits for the server identification string, and sends our own | |
317 | * identification string. | |
318 | */ | |
319 | void | |
320 | ssh_exchange_identification() | |
8efc0c15 | 321 | { |
5260325f | 322 | char buf[256], remote_version[256]; /* must be same size! */ |
a8be9f80 | 323 | int remote_major, remote_minor, i, mismatch; |
5260325f | 324 | int connection_in = packet_get_connection_in(); |
325 | int connection_out = packet_get_connection_out(); | |
5260325f | 326 | |
327 | /* Read other side\'s version identification. */ | |
328 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
c8d54615 | 329 | int len = read(connection_in, &buf[i], 1); |
330 | if (len < 0) | |
5260325f | 331 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); |
c8d54615 | 332 | if (len != 1) |
333 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
5260325f | 334 | if (buf[i] == '\r') { |
335 | buf[i] = '\n'; | |
336 | buf[i + 1] = 0; | |
8ce64345 | 337 | continue; /**XXX wait for \n */ |
5260325f | 338 | } |
339 | if (buf[i] == '\n') { | |
340 | buf[i + 1] = 0; | |
341 | break; | |
342 | } | |
8efc0c15 | 343 | } |
5260325f | 344 | buf[sizeof(buf) - 1] = 0; |
8ce64345 | 345 | server_version_string = xstrdup(buf); |
5260325f | 346 | |
aa3378df | 347 | /* |
348 | * Check that the versions match. In future this might accept | |
349 | * several versions and set appropriate flags to handle them. | |
350 | */ | |
8ce64345 | 351 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", |
352 | &remote_major, &remote_minor, remote_version) != 3) | |
5260325f | 353 | fatal("Bad remote protocol version identification: '%.100s'", buf); |
354 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
355 | remote_major, remote_minor, remote_version); | |
356 | ||
8ce64345 | 357 | compat_datafellows(remote_version); |
a8be9f80 | 358 | mismatch = 0; |
359 | ||
360 | switch(remote_major) { | |
361 | case 1: | |
362 | if (remote_minor == 99 && | |
363 | (options.protocol & SSH_PROTO_2) && | |
364 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
365 | enable_compat20(); | |
366 | break; | |
5260325f | 367 | } |
a8be9f80 | 368 | if (!(options.protocol & SSH_PROTO_1)) { |
369 | mismatch = 1; | |
370 | break; | |
371 | } | |
372 | if (remote_minor < 3) { | |
373 | fatal("Remote machine has too old SSH software version."); | |
374 | } else if (remote_minor == 3) { | |
375 | /* We speak 1.3, too. */ | |
376 | enable_compat13(); | |
377 | if (options.forward_agent) { | |
378 | log("Agent forwarding disabled for protocol 1.3"); | |
379 | options.forward_agent = 0; | |
380 | } | |
381 | } | |
382 | break; | |
383 | case 2: | |
384 | if (options.protocol & SSH_PROTO_2) { | |
385 | enable_compat20(); | |
386 | break; | |
387 | } | |
388 | /* FALLTHROUGH */ | |
6ae2364d | 389 | default: |
a8be9f80 | 390 | mismatch = 1; |
391 | break; | |
8efc0c15 | 392 | } |
a8be9f80 | 393 | if (mismatch) |
5260325f | 394 | fatal("Protocol major versions differ: %d vs. %d", |
a8be9f80 | 395 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
396 | remote_major); | |
a306f2dd | 397 | if (compat20) |
398 | packet_set_ssh2_format(); | |
5260325f | 399 | /* Send our own protocol version identification. */ |
400 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
a8be9f80 | 401 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
402 | compat20 ? PROTOCOL_MINOR_2 : PROTOCOL_MINOR_1, | |
8ce64345 | 403 | SSH_VERSION); |
a408af76 | 404 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) |
5260325f | 405 | fatal("write: %.100s", strerror(errno)); |
8ce64345 | 406 | client_version_string = xstrdup(buf); |
407 | chop(client_version_string); | |
408 | chop(server_version_string); | |
409 | debug("Local version string %.100s", client_version_string); | |
8efc0c15 | 410 | } |
411 | ||
5260325f | 412 | int |
413 | read_yes_or_no(const char *prompt, int defval) | |
8efc0c15 | 414 | { |
5260325f | 415 | char buf[1024]; |
416 | FILE *f; | |
417 | int retval = -1; | |
418 | ||
419 | if (isatty(0)) | |
420 | f = stdin; | |
421 | else | |
422 | f = fopen("/dev/tty", "rw"); | |
423 | ||
424 | if (f == NULL) | |
425 | return 0; | |
426 | ||
427 | fflush(stdout); | |
428 | ||
429 | while (1) { | |
430 | fprintf(stderr, "%s", prompt); | |
431 | if (fgets(buf, sizeof(buf), f) == NULL) { | |
432 | /* Print a newline (the prompt probably didn\'t have one). */ | |
433 | fprintf(stderr, "\n"); | |
434 | strlcpy(buf, "no", sizeof buf); | |
435 | } | |
436 | /* Remove newline from response. */ | |
437 | if (strchr(buf, '\n')) | |
438 | *strchr(buf, '\n') = 0; | |
439 | ||
440 | if (buf[0] == 0) | |
441 | retval = defval; | |
442 | if (strcmp(buf, "yes") == 0) | |
443 | retval = 1; | |
444 | if (strcmp(buf, "no") == 0) | |
445 | retval = 0; | |
446 | ||
447 | if (retval != -1) { | |
448 | if (f != stdin) | |
449 | fclose(f); | |
450 | return retval; | |
451 | } | |
8efc0c15 | 452 | } |
8efc0c15 | 453 | } |
454 | ||
5260325f | 455 | /* |
95f1eccc | 456 | * check whether the supplied host key is valid, return only if ok. |
5260325f | 457 | */ |
95f1eccc | 458 | |
5260325f | 459 | void |
a306f2dd | 460 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, |
461 | const char *user_hostfile, const char *system_hostfile) | |
8efc0c15 | 462 | { |
4fe2af09 | 463 | Key *file_key; |
95f1eccc | 464 | char *ip = NULL; |
5260325f | 465 | char hostline[1000], *hostp; |
5260325f | 466 | HostStatus host_status; |
467 | HostStatus ip_status; | |
48e671d5 | 468 | int local = 0, host_ip_differ = 0; |
20af321f | 469 | int salen; |
48e671d5 | 470 | char ntop[NI_MAXHOST]; |
471 | ||
472 | /* | |
473 | * Force accepting of the host key for loopback/localhost. The | |
474 | * problem is that if the home directory is NFS-mounted to multiple | |
475 | * machines, localhost will refer to a different machine in each of | |
476 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
477 | * essentially disables host authentication for localhost; however, | |
478 | * this is probably not a real problem. | |
479 | */ | |
a306f2dd | 480 | /** hostaddr == 0! */ |
48e671d5 | 481 | switch (hostaddr->sa_family) { |
482 | case AF_INET: | |
483 | local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; | |
20af321f | 484 | salen = sizeof(struct sockaddr_in); |
48e671d5 | 485 | break; |
486 | case AF_INET6: | |
487 | local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
20af321f | 488 | salen = sizeof(struct sockaddr_in6); |
48e671d5 | 489 | break; |
490 | default: | |
491 | local = 0; | |
20af321f | 492 | salen = sizeof(struct sockaddr_storage); |
48e671d5 | 493 | break; |
494 | } | |
495 | if (local) { | |
496 | debug("Forcing accepting of host key for loopback/localhost."); | |
497 | return; | |
498 | } | |
5260325f | 499 | |
57112b5a | 500 | /* |
501 | * Turn off check_host_ip for proxy connects, since | |
502 | * we don't have the remote ip-address | |
503 | */ | |
504 | if (options.proxy_command != NULL && options.check_host_ip) | |
505 | options.check_host_ip = 0; | |
506 | ||
48e671d5 | 507 | if (options.check_host_ip) { |
20af321f | 508 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), |
48e671d5 | 509 | NULL, 0, NI_NUMERICHOST) != 0) |
510 | fatal("check_host_key: getnameinfo failed"); | |
511 | ip = xstrdup(ntop); | |
512 | } | |
5260325f | 513 | |
95f1eccc | 514 | /* |
515 | * Store the host key from the known host file in here so that we can | |
516 | * compare it with the key for the IP address. | |
517 | */ | |
4fe2af09 | 518 | file_key = key_new(host_key->type); |
5260325f | 519 | |
aa3378df | 520 | /* |
521 | * Check if the host key is present in the user\'s list of known | |
522 | * hosts or in the systemwide list. | |
523 | */ | |
a306f2dd | 524 | host_status = check_host_in_hostfile(user_hostfile, host, host_key, file_key); |
5260325f | 525 | if (host_status == HOST_NEW) |
a306f2dd | 526 | host_status = check_host_in_hostfile(system_hostfile, host, host_key, file_key); |
aa3378df | 527 | /* |
528 | * Also perform check for the ip address, skip the check if we are | |
529 | * localhost or the hostname was an ip address to begin with | |
530 | */ | |
5260325f | 531 | if (options.check_host_ip && !local && strcmp(host, ip)) { |
4fe2af09 | 532 | Key *ip_key = key_new(host_key->type); |
a306f2dd | 533 | ip_status = check_host_in_hostfile(user_hostfile, ip, host_key, ip_key); |
5260325f | 534 | |
535 | if (ip_status == HOST_NEW) | |
a306f2dd | 536 | ip_status = check_host_in_hostfile(system_hostfile, ip, host_key, ip_key); |
5260325f | 537 | if (host_status == HOST_CHANGED && |
4fe2af09 | 538 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) |
5260325f | 539 | host_ip_differ = 1; |
540 | ||
4fe2af09 | 541 | key_free(ip_key); |
5260325f | 542 | } else |
543 | ip_status = host_status; | |
544 | ||
4fe2af09 | 545 | key_free(file_key); |
5260325f | 546 | |
547 | switch (host_status) { | |
548 | case HOST_OK: | |
549 | /* The host is known and the key matches. */ | |
550 | debug("Host '%.200s' is known and matches the host key.", host); | |
551 | if (options.check_host_ip) { | |
552 | if (ip_status == HOST_NEW) { | |
a306f2dd | 553 | if (!add_host_to_hostfile(user_hostfile, ip, host_key)) |
5260325f | 554 | log("Failed to add the host key for IP address '%.30s' to the list of known hosts (%.30s).", |
a306f2dd | 555 | ip, user_hostfile); |
5260325f | 556 | else |
557 | log("Warning: Permanently added host key for IP address '%.30s' to the list of known hosts.", | |
558 | ip); | |
559 | } else if (ip_status != HOST_OK) | |
560 | log("Warning: the host key for '%.200s' differs from the key for the IP address '%.30s'", | |
561 | 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 host key is known for %.200s and you have requested strict checking.", host); | |
570 | } else if (options.strict_host_key_checking == 2) { | |
571 | /* The default */ | |
572 | char prompt[1024]; | |
4fe2af09 | 573 | char *fp = key_fingerprint(host_key); |
5260325f | 574 | snprintf(prompt, sizeof(prompt), |
a408af76 | 575 | "The authenticity of host '%.200s' can't be established.\n" |
4fe2af09 | 576 | "Key fingerprint is %s.\n" |
a408af76 | 577 | "Are you sure you want to continue connecting (yes/no)? ", |
4fe2af09 | 578 | host, fp); |
5260325f | 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. */ | |
a306f2dd | 589 | if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) |
5260325f | 590 | log("Failed to add the host to the list of known hosts (%.500s).", |
a306f2dd | 591 | user_hostfile); |
5260325f | 592 | else |
593 | log("Warning: Permanently added '%.200s' to the list of known hosts.", | |
594 | hostp); | |
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 host key for %s has changed,", 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("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
ae2f7af7 | 616 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); |
5260325f | 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 host key has just been changed."); | |
621 | error("Please contact your system administrator."); | |
622 | error("Add correct host key in %.100s to get rid of this message.", | |
a306f2dd | 623 | user_hostfile); |
5260325f | 624 | |
aa3378df | 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 | */ | |
5260325f | 629 | if (options.strict_host_key_checking) |
630 | fatal("Host key for %.200s has changed and you have requested strict checking.", host); | |
631 | ||
aa3378df | 632 | /* |
633 | * If strict host key checking has not been requested, allow | |
634 | * the connection but without password authentication or | |
635 | * agent forwarding. | |
636 | */ | |
5260325f | 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 | } | |
aa3378df | 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 | */ | |
5260325f | 652 | break; |
653 | } | |
5260325f | 654 | if (options.check_host_ip) |
655 | xfree(ip); | |
95f1eccc | 656 | } |
657 | ||
8ce64345 | 658 | /* |
a306f2dd | 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. | |
8ce64345 | 664 | */ |
665 | void | |
a306f2dd | 666 | ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost, |
667 | struct sockaddr *hostaddr, uid_t original_real_uid) | |
8ce64345 | 668 | { |
8ce64345 | 669 | struct passwd *pw; |
a306f2dd | 670 | char *host, *cp; |
8ce64345 | 671 | char *server_user, *local_user; |
8ce64345 | 672 | |
8ce64345 | 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 %d 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 | ||
7b2ea3a1 | 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 | ||
7b2ea3a1 | 692 | /* key exchange */ |
7b2ea3a1 | 693 | /* authenticate user */ |
8ce64345 | 694 | if (compat20) { |
695 | ssh_kex2(host, hostaddr); | |
a306f2dd | 696 | ssh_userauth2(server_user, host); |
8ce64345 | 697 | } else { |
8ce64345 | 698 | ssh_kex(host, hostaddr); |
a306f2dd | 699 | ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key); |
8ce64345 | 700 | } |
7b2ea3a1 | 701 | } |