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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 | |
5260325f | 5 | * Code to connect to a remote host, and to perform the client side of the |
6 | * login (authentication) dialog. | |
bcbf86ec | 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". | |
5260325f | 13 | */ |
8efc0c15 | 14 | |
15 | #include "includes.h" | |
b5c334cc | 16 | RCSID("$OpenBSD: sshconnect.c,v 1.90 2001/01/13 18:32:50 markus Exp $"); |
8efc0c15 | 17 | |
8ce64345 | 18 | #include <openssl/bn.h> |
a306f2dd | 19 | #include <openssl/dsa.h> |
20 | #include <openssl/rsa.h> | |
21 | ||
8efc0c15 | 22 | #include "xmalloc.h" |
23 | #include "rsa.h" | |
24 | #include "ssh.h" | |
8ce64345 | 25 | #include "buffer.h" |
8efc0c15 | 26 | #include "packet.h" |
8efc0c15 | 27 | #include "uidswap.h" |
28 | #include "compat.h" | |
6fa724bc | 29 | #include "readconf.h" |
4fe2af09 | 30 | #include "key.h" |
a306f2dd | 31 | #include "sshconnect.h" |
4fe2af09 | 32 | #include "hostfile.h" |
8efc0c15 | 33 | |
a306f2dd | 34 | char *client_version_string = NULL; |
35 | char *server_version_string = NULL; | |
8ce64345 | 36 | |
57112b5a | 37 | extern Options options; |
48e671d5 | 38 | extern char *__progname; |
57112b5a | 39 | |
5260325f | 40 | /* |
41 | * Connect to the given ssh server using a proxy command. | |
42 | */ | |
8efc0c15 | 43 | int |
57112b5a | 44 | ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid, |
8efc0c15 | 45 | const char *proxy_command) |
46 | { | |
5260325f | 47 | Buffer command; |
48 | const char *cp; | |
49 | char *command_string; | |
50 | int pin[2], pout[2]; | |
9da5c3c9 | 51 | pid_t pid; |
48e671d5 | 52 | char strport[NI_MAXSERV]; |
5260325f | 53 | |
54 | /* Convert the port number into a string. */ | |
48e671d5 | 55 | snprintf(strport, sizeof strport, "%hu", port); |
5260325f | 56 | |
57 | /* Build the final command string in the buffer by making the | |
58 | appropriate substitutions to the given proxy command. */ | |
59 | buffer_init(&command); | |
60 | for (cp = proxy_command; *cp; cp++) { | |
61 | if (cp[0] == '%' && cp[1] == '%') { | |
62 | buffer_append(&command, "%", 1); | |
63 | cp++; | |
64 | continue; | |
65 | } | |
66 | if (cp[0] == '%' && cp[1] == 'h') { | |
67 | buffer_append(&command, host, strlen(host)); | |
68 | cp++; | |
69 | continue; | |
70 | } | |
71 | if (cp[0] == '%' && cp[1] == 'p') { | |
48e671d5 | 72 | buffer_append(&command, strport, strlen(strport)); |
5260325f | 73 | cp++; |
74 | continue; | |
75 | } | |
76 | buffer_append(&command, cp, 1); | |
8efc0c15 | 77 | } |
5260325f | 78 | buffer_append(&command, "\0", 1); |
79 | ||
80 | /* Get the final command string. */ | |
81 | command_string = buffer_ptr(&command); | |
82 | ||
83 | /* Create pipes for communicating with the proxy. */ | |
84 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
85 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
86 | strerror(errno)); | |
87 | ||
88 | debug("Executing proxy command: %.500s", command_string); | |
89 | ||
90 | /* Fork and execute the proxy command. */ | |
91 | if ((pid = fork()) == 0) { | |
92 | char *argv[10]; | |
93 | ||
94 | /* Child. Permanently give up superuser privileges. */ | |
95 | permanently_set_uid(original_real_uid); | |
96 | ||
97 | /* Redirect stdin and stdout. */ | |
98 | close(pin[1]); | |
99 | if (pin[0] != 0) { | |
100 | if (dup2(pin[0], 0) < 0) | |
101 | perror("dup2 stdin"); | |
102 | close(pin[0]); | |
103 | } | |
104 | close(pout[0]); | |
105 | if (dup2(pout[1], 1) < 0) | |
106 | perror("dup2 stdout"); | |
107 | /* Cannot be 1 because pin allocated two descriptors. */ | |
108 | close(pout[1]); | |
109 | ||
110 | /* Stderr is left as it is so that error messages get | |
111 | printed on the user's terminal. */ | |
30228d7c | 112 | argv[0] = _PATH_BSHELL; |
5260325f | 113 | argv[1] = "-c"; |
114 | argv[2] = command_string; | |
115 | argv[3] = NULL; | |
116 | ||
117 | /* Execute the proxy command. Note that we gave up any | |
118 | extra privileges above. */ | |
328654d8 | 119 | execv(argv[0], argv); |
120 | perror(argv[0]); | |
5260325f | 121 | exit(1); |
8efc0c15 | 122 | } |
5260325f | 123 | /* Parent. */ |
124 | if (pid < 0) | |
125 | fatal("fork failed: %.100s", strerror(errno)); | |
126 | ||
127 | /* Close child side of the descriptors. */ | |
128 | close(pin[0]); | |
129 | close(pout[1]); | |
130 | ||
131 | /* Free the command name. */ | |
132 | buffer_free(&command); | |
133 | ||
134 | /* Set the connection file descriptors. */ | |
135 | packet_set_connection(pout[0], pin[1]); | |
8efc0c15 | 136 | |
5260325f | 137 | return 1; |
138 | } | |
8efc0c15 | 139 | |
5260325f | 140 | /* |
141 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
142 | */ | |
143 | int | |
48e671d5 | 144 | ssh_create_socket(uid_t original_real_uid, int privileged, int family) |
8efc0c15 | 145 | { |
5260325f | 146 | int sock; |
147 | ||
aa3378df | 148 | /* |
149 | * If we are running as root and want to connect to a privileged | |
150 | * port, bind our own socket to a privileged port. | |
151 | */ | |
5260325f | 152 | if (privileged) { |
153 | int p = IPPORT_RESERVED - 1; | |
48e671d5 | 154 | sock = rresvport_af(&p, family); |
5260325f | 155 | if (sock < 0) |
c8d54615 | 156 | error("rresvport: af=%d %.100s", family, strerror(errno)); |
157 | else | |
158 | debug("Allocated local port %d.", p); | |
5260325f | 159 | } else { |
95f1eccc | 160 | /* |
161 | * Just create an ordinary socket on arbitrary port. We use | |
162 | * the user's uid to create the socket. | |
163 | */ | |
5260325f | 164 | temporarily_use_uid(original_real_uid); |
48e671d5 | 165 | sock = socket(family, SOCK_STREAM, 0); |
5260325f | 166 | if (sock < 0) |
48e671d5 | 167 | error("socket: %.100s", strerror(errno)); |
5260325f | 168 | restore_uid(); |
169 | } | |
170 | return sock; | |
8efc0c15 | 171 | } |
172 | ||
5260325f | 173 | /* |
48e671d5 | 174 | * Opens a TCP/IP connection to the remote server on the given host. |
175 | * The address of the remote host will be returned in hostaddr. | |
176 | * If port is 0, the default port will be used. If anonymous is zero, | |
5260325f | 177 | * a privileged port will be allocated to make the connection. |
178 | * This requires super-user privileges if anonymous is false. | |
179 | * Connection_attempts specifies the maximum number of tries (one per | |
180 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
181 | * and %p substituted for host and port, respectively) to use to contact | |
182 | * the daemon. | |
183 | */ | |
184 | int | |
48e671d5 | 185 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, |
57112b5a | 186 | u_short port, int connection_attempts, |
5260325f | 187 | int anonymous, uid_t original_real_uid, |
188 | const char *proxy_command) | |
8efc0c15 | 189 | { |
b5c334cc | 190 | int gaierr; |
191 | int on = 1; | |
48e671d5 | 192 | int sock = -1, attempt; |
48e671d5 | 193 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; |
b5c334cc | 194 | struct addrinfo hints, *ai, *aitop; |
5260325f | 195 | struct linger linger; |
b5c334cc | 196 | struct servent *sp; |
5260325f | 197 | |
14a9a859 | 198 | debug("ssh_connect: getuid %u geteuid %u anon %d", |
199 | (u_int) getuid(), (u_int) geteuid(), anonymous); | |
5260325f | 200 | |
201 | /* Get default port if port has not been set. */ | |
202 | if (port == 0) { | |
203 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
204 | if (sp) | |
205 | port = ntohs(sp->s_port); | |
206 | else | |
207 | port = SSH_DEFAULT_PORT; | |
8efc0c15 | 208 | } |
5260325f | 209 | /* If a proxy command is given, connect using it. */ |
210 | if (proxy_command != NULL) | |
211 | return ssh_proxy_connect(host, port, original_real_uid, proxy_command); | |
212 | ||
213 | /* No proxy command. */ | |
214 | ||
48e671d5 | 215 | memset(&hints, 0, sizeof(hints)); |
216 | hints.ai_family = IPv4or6; | |
217 | hints.ai_socktype = SOCK_STREAM; | |
218 | snprintf(strport, sizeof strport, "%d", port); | |
219 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) | |
220 | fatal("%s: %.100s: %s", __progname, host, | |
221 | gai_strerror(gaierr)); | |
5260325f | 222 | |
95f1eccc | 223 | /* |
224 | * Try to connect several times. On some machines, the first time | |
225 | * will sometimes fail. In general socket code appears to behave | |
226 | * quite magically on many machines. | |
227 | */ | |
5260325f | 228 | for (attempt = 0; attempt < connection_attempts; attempt++) { |
229 | if (attempt > 0) | |
230 | debug("Trying again..."); | |
231 | ||
48e671d5 | 232 | /* Loop through addresses for this host, and try each one in |
6ae2364d | 233 | sequence until the connection succeeds. */ |
48e671d5 | 234 | for (ai = aitop; ai; ai = ai->ai_next) { |
235 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
236 | continue; | |
237 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
238 | ntop, sizeof(ntop), strport, sizeof(strport), | |
239 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
240 | error("ssh_connect: getnameinfo failed"); | |
241 | continue; | |
242 | } | |
243 | debug("Connecting to %.200s [%.100s] port %s.", | |
244 | host, ntop, strport); | |
245 | ||
246 | /* Create a socket for connecting. */ | |
6ae2364d | 247 | sock = ssh_create_socket(original_real_uid, |
3c62e7eb | 248 | #ifdef HAVE_CYGWIN |
fa08c86b | 249 | !anonymous, |
3c62e7eb | 250 | #else |
fa08c86b | 251 | !anonymous && geteuid() == 0, |
3c62e7eb | 252 | #endif |
48e671d5 | 253 | ai->ai_family); |
254 | if (sock < 0) | |
255 | continue; | |
256 | ||
257 | /* Connect to the host. We use the user's uid in the | |
258 | * hope that it will help with tcp_wrappers showing | |
259 | * the remote uid as root. | |
aa3378df | 260 | */ |
5260325f | 261 | temporarily_use_uid(original_real_uid); |
48e671d5 | 262 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { |
263 | /* Successful connection. */ | |
3d1a1654 | 264 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); |
5260325f | 265 | restore_uid(); |
266 | break; | |
48e671d5 | 267 | } else { |
5260325f | 268 | debug("connect: %.100s", strerror(errno)); |
269 | restore_uid(); | |
aa3378df | 270 | /* |
271 | * Close the failed socket; there appear to | |
272 | * be some problems when reusing a socket for | |
273 | * which connect() has already returned an | |
274 | * error. | |
275 | */ | |
5260325f | 276 | shutdown(sock, SHUT_RDWR); |
277 | close(sock); | |
278 | } | |
8efc0c15 | 279 | } |
48e671d5 | 280 | if (ai) |
281 | break; /* Successful connection. */ | |
8efc0c15 | 282 | |
5260325f | 283 | /* Sleep a moment before retrying. */ |
284 | sleep(1); | |
285 | } | |
48e671d5 | 286 | |
287 | freeaddrinfo(aitop); | |
288 | ||
5260325f | 289 | /* Return failure if we didn't get a successful connection. */ |
290 | if (attempt >= connection_attempts) | |
291 | return 0; | |
8efc0c15 | 292 | |
5260325f | 293 | debug("Connection established."); |
8efc0c15 | 294 | |
aa3378df | 295 | /* |
296 | * Set socket options. We would like the socket to disappear as soon | |
297 | * as it has been closed for whatever reason. | |
298 | */ | |
299 | /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 300 | linger.l_onoff = 1; |
301 | linger.l_linger = 5; | |
b5c334cc | 302 | setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger)); |
303 | ||
304 | /* Set keepalives if requested. */ | |
305 | if (options.keepalives && | |
306 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, | |
307 | sizeof(on)) < 0) | |
308 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
8efc0c15 | 309 | |
5260325f | 310 | /* Set the connection. */ |
311 | packet_set_connection(sock, sock); | |
8efc0c15 | 312 | |
5260325f | 313 | return 1; |
8efc0c15 | 314 | } |
315 | ||
5260325f | 316 | /* |
317 | * Waits for the server identification string, and sends our own | |
318 | * identification string. | |
319 | */ | |
320 | void | |
321 | ssh_exchange_identification() | |
8efc0c15 | 322 | { |
5260325f | 323 | char buf[256], remote_version[256]; /* must be same size! */ |
a8be9f80 | 324 | int remote_major, remote_minor, i, mismatch; |
5260325f | 325 | int connection_in = packet_get_connection_in(); |
326 | int connection_out = packet_get_connection_out(); | |
fa08c86b | 327 | int minor1 = PROTOCOL_MINOR_1; |
5260325f | 328 | |
329 | /* Read other side\'s version identification. */ | |
38c295d6 | 330 | for (;;) { |
331 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
332 | int len = atomicio(read, connection_in, &buf[i], 1); | |
333 | if (len < 0) | |
334 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); | |
335 | if (len != 1) | |
336 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
337 | if (buf[i] == '\r') { | |
338 | buf[i] = '\n'; | |
339 | buf[i + 1] = 0; | |
340 | continue; /**XXX wait for \n */ | |
341 | } | |
342 | if (buf[i] == '\n') { | |
343 | buf[i + 1] = 0; | |
344 | break; | |
345 | } | |
5260325f | 346 | } |
38c295d6 | 347 | buf[sizeof(buf) - 1] = 0; |
348 | if (strncmp(buf, "SSH-", 4) == 0) | |
5260325f | 349 | break; |
38c295d6 | 350 | debug("ssh_exchange_identification: %s", buf); |
8efc0c15 | 351 | } |
8ce64345 | 352 | server_version_string = xstrdup(buf); |
5260325f | 353 | |
aa3378df | 354 | /* |
355 | * Check that the versions match. In future this might accept | |
356 | * several versions and set appropriate flags to handle them. | |
357 | */ | |
8ce64345 | 358 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", |
359 | &remote_major, &remote_minor, remote_version) != 3) | |
5260325f | 360 | fatal("Bad remote protocol version identification: '%.100s'", buf); |
361 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
362 | remote_major, remote_minor, remote_version); | |
363 | ||
8ce64345 | 364 | compat_datafellows(remote_version); |
a8be9f80 | 365 | mismatch = 0; |
366 | ||
367 | switch(remote_major) { | |
368 | case 1: | |
369 | if (remote_minor == 99 && | |
370 | (options.protocol & SSH_PROTO_2) && | |
371 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
372 | enable_compat20(); | |
373 | break; | |
5260325f | 374 | } |
a8be9f80 | 375 | if (!(options.protocol & SSH_PROTO_1)) { |
376 | mismatch = 1; | |
377 | break; | |
378 | } | |
379 | if (remote_minor < 3) { | |
380 | fatal("Remote machine has too old SSH software version."); | |
fa08c86b | 381 | } else if (remote_minor == 3 || remote_minor == 4) { |
a8be9f80 | 382 | /* We speak 1.3, too. */ |
383 | enable_compat13(); | |
fa08c86b | 384 | minor1 = 3; |
a8be9f80 | 385 | if (options.forward_agent) { |
386 | log("Agent forwarding disabled for protocol 1.3"); | |
387 | options.forward_agent = 0; | |
388 | } | |
389 | } | |
390 | break; | |
391 | case 2: | |
392 | if (options.protocol & SSH_PROTO_2) { | |
393 | enable_compat20(); | |
394 | break; | |
395 | } | |
396 | /* FALLTHROUGH */ | |
6ae2364d | 397 | default: |
a8be9f80 | 398 | mismatch = 1; |
399 | break; | |
8efc0c15 | 400 | } |
a8be9f80 | 401 | if (mismatch) |
5260325f | 402 | fatal("Protocol major versions differ: %d vs. %d", |
a8be9f80 | 403 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
404 | remote_major); | |
a306f2dd | 405 | if (compat20) |
406 | packet_set_ssh2_format(); | |
5260325f | 407 | /* Send our own protocol version identification. */ |
408 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
a8be9f80 | 409 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
fa08c86b | 410 | compat20 ? PROTOCOL_MINOR_2 : minor1, |
8ce64345 | 411 | SSH_VERSION); |
a408af76 | 412 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) |
5260325f | 413 | fatal("write: %.100s", strerror(errno)); |
8ce64345 | 414 | client_version_string = xstrdup(buf); |
415 | chop(client_version_string); | |
416 | chop(server_version_string); | |
417 | debug("Local version string %.100s", client_version_string); | |
8efc0c15 | 418 | } |
419 | ||
5260325f | 420 | int |
421 | read_yes_or_no(const char *prompt, int defval) | |
8efc0c15 | 422 | { |
5260325f | 423 | char buf[1024]; |
424 | FILE *f; | |
425 | int retval = -1; | |
426 | ||
7c49df64 | 427 | if (isatty(STDIN_FILENO)) |
5260325f | 428 | f = stdin; |
429 | else | |
430 | f = fopen("/dev/tty", "rw"); | |
431 | ||
432 | if (f == NULL) | |
433 | return 0; | |
434 | ||
435 | fflush(stdout); | |
436 | ||
437 | while (1) { | |
438 | fprintf(stderr, "%s", prompt); | |
439 | if (fgets(buf, sizeof(buf), f) == NULL) { | |
440 | /* Print a newline (the prompt probably didn\'t have one). */ | |
441 | fprintf(stderr, "\n"); | |
442 | strlcpy(buf, "no", sizeof buf); | |
443 | } | |
444 | /* Remove newline from response. */ | |
445 | if (strchr(buf, '\n')) | |
446 | *strchr(buf, '\n') = 0; | |
447 | ||
448 | if (buf[0] == 0) | |
449 | retval = defval; | |
450 | if (strcmp(buf, "yes") == 0) | |
451 | retval = 1; | |
188adeb2 | 452 | else if (strcmp(buf, "no") == 0) |
5260325f | 453 | retval = 0; |
188adeb2 | 454 | else |
455 | fprintf(stderr, "Please type 'yes' or 'no'.\n"); | |
5260325f | 456 | |
457 | if (retval != -1) { | |
458 | if (f != stdin) | |
459 | fclose(f); | |
460 | return retval; | |
461 | } | |
8efc0c15 | 462 | } |
8efc0c15 | 463 | } |
464 | ||
5260325f | 465 | /* |
95f1eccc | 466 | * check whether the supplied host key is valid, return only if ok. |
5260325f | 467 | */ |
95f1eccc | 468 | |
5260325f | 469 | void |
a306f2dd | 470 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, |
471 | const char *user_hostfile, const char *system_hostfile) | |
8efc0c15 | 472 | { |
4fe2af09 | 473 | Key *file_key; |
1d1ffb87 | 474 | char *type = key_type(host_key); |
95f1eccc | 475 | char *ip = NULL; |
5260325f | 476 | char hostline[1000], *hostp; |
5260325f | 477 | HostStatus host_status; |
478 | HostStatus ip_status; | |
48e671d5 | 479 | int local = 0, host_ip_differ = 0; |
20af321f | 480 | int salen; |
48e671d5 | 481 | char ntop[NI_MAXHOST]; |
7c49df64 | 482 | int host_line, ip_line; |
1e3b8b07 | 483 | const char *host_file = NULL, *ip_file = NULL; |
48e671d5 | 484 | |
485 | /* | |
486 | * Force accepting of the host key for loopback/localhost. The | |
487 | * problem is that if the home directory is NFS-mounted to multiple | |
488 | * machines, localhost will refer to a different machine in each of | |
489 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
490 | * essentially disables host authentication for localhost; however, | |
491 | * this is probably not a real problem. | |
492 | */ | |
a306f2dd | 493 | /** hostaddr == 0! */ |
48e671d5 | 494 | switch (hostaddr->sa_family) { |
495 | case AF_INET: | |
496 | local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; | |
20af321f | 497 | salen = sizeof(struct sockaddr_in); |
48e671d5 | 498 | break; |
499 | case AF_INET6: | |
500 | local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
20af321f | 501 | salen = sizeof(struct sockaddr_in6); |
48e671d5 | 502 | break; |
503 | default: | |
504 | local = 0; | |
20af321f | 505 | salen = sizeof(struct sockaddr_storage); |
48e671d5 | 506 | break; |
507 | } | |
7c49df64 | 508 | if (local && options.host_key_alias == NULL) { |
509 | debug("Forcing accepting of host key for " | |
510 | "loopback/localhost."); | |
511 | return; | |
48e671d5 | 512 | } |
5260325f | 513 | |
57112b5a | 514 | /* |
7c49df64 | 515 | * We don't have the remote ip-address for connections |
516 | * using a proxy command | |
517 | */ | |
518 | if (options.proxy_command == NULL) { | |
519 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), | |
520 | NULL, 0, NI_NUMERICHOST) != 0) | |
521 | fatal("check_host_key: getnameinfo failed"); | |
522 | ip = xstrdup(ntop); | |
523 | } else { | |
524 | ip = xstrdup("<no hostip for proxy command>"); | |
525 | } | |
526 | /* | |
527 | * Turn off check_host_ip if the connection is to localhost, via proxy | |
528 | * command or if we don't have a hostname to compare with | |
57112b5a | 529 | */ |
7c49df64 | 530 | if (options.check_host_ip && |
531 | (local || strcmp(host, ip) == 0 || options.proxy_command != NULL)) | |
57112b5a | 532 | options.check_host_ip = 0; |
533 | ||
8abcdba4 | 534 | /* |
7c49df64 | 535 | * Allow the user to record the key under a different name. This is |
8abcdba4 | 536 | * useful for ssh tunneling over forwarded connections or if you run |
7c49df64 | 537 | * multiple sshd's on different ports on the same machine. |
8abcdba4 | 538 | */ |
539 | if (options.host_key_alias != NULL) { | |
540 | host = options.host_key_alias; | |
541 | debug("using hostkeyalias: %s", host); | |
542 | } | |
543 | ||
95f1eccc | 544 | /* |
545 | * Store the host key from the known host file in here so that we can | |
546 | * compare it with the key for the IP address. | |
547 | */ | |
4fe2af09 | 548 | file_key = key_new(host_key->type); |
5260325f | 549 | |
aa3378df | 550 | /* |
551 | * Check if the host key is present in the user\'s list of known | |
552 | * hosts or in the systemwide list. | |
553 | */ | |
1e3b8b07 | 554 | host_file = user_hostfile; |
555 | host_status = check_host_in_hostfile(host_file, host, host_key, file_key, &host_line); | |
556 | if (host_status == HOST_NEW) { | |
557 | host_file = system_hostfile; | |
558 | host_status = check_host_in_hostfile(host_file, host, host_key, file_key, &host_line); | |
559 | } | |
aa3378df | 560 | /* |
561 | * Also perform check for the ip address, skip the check if we are | |
562 | * localhost or the hostname was an ip address to begin with | |
563 | */ | |
7c49df64 | 564 | if (options.check_host_ip) { |
4fe2af09 | 565 | Key *ip_key = key_new(host_key->type); |
5260325f | 566 | |
1e3b8b07 | 567 | ip_file = user_hostfile; |
568 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, ip_key, &ip_line); | |
569 | if (ip_status == HOST_NEW) { | |
570 | ip_file = system_hostfile; | |
571 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, ip_key, &ip_line); | |
572 | } | |
5260325f | 573 | if (host_status == HOST_CHANGED && |
4fe2af09 | 574 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) |
5260325f | 575 | host_ip_differ = 1; |
576 | ||
4fe2af09 | 577 | key_free(ip_key); |
5260325f | 578 | } else |
579 | ip_status = host_status; | |
580 | ||
4fe2af09 | 581 | key_free(file_key); |
5260325f | 582 | |
583 | switch (host_status) { | |
584 | case HOST_OK: | |
585 | /* The host is known and the key matches. */ | |
1d1ffb87 | 586 | debug("Host '%.200s' is known and matches the %s host key.", |
587 | host, type); | |
1e3b8b07 | 588 | debug("Found key in %s:%d", host_file, host_line); |
7c49df64 | 589 | if (options.check_host_ip && ip_status == HOST_NEW) { |
590 | if (!add_host_to_hostfile(user_hostfile, ip, host_key)) | |
591 | log("Failed to add the %s host key for IP address '%.30s' to the list of known hosts (%.30s).", | |
592 | type, ip, user_hostfile); | |
593 | else | |
594 | log("Warning: Permanently added the %s host key for IP address '%.30s' to the list of known hosts.", | |
595 | type, ip); | |
5260325f | 596 | } |
597 | break; | |
598 | case HOST_NEW: | |
599 | /* The host is new. */ | |
600 | if (options.strict_host_key_checking == 1) { | |
601 | /* User has requested strict host key checking. We will not add the host key | |
602 | automatically. The only alternative left is to abort. */ | |
1d1ffb87 | 603 | fatal("No %s host key is known for %.200s and you have requested strict checking.", type, host); |
5260325f | 604 | } else if (options.strict_host_key_checking == 2) { |
605 | /* The default */ | |
606 | char prompt[1024]; | |
5260325f | 607 | snprintf(prompt, sizeof(prompt), |
0b6fbf03 | 608 | "The authenticity of host '%.200s (%s)' can't be established.\n" |
1d1ffb87 | 609 | "%s key fingerprint is %s.\n" |
a408af76 | 610 | "Are you sure you want to continue connecting (yes/no)? ", |
8abcdba4 | 611 | host, ip, type, key_fingerprint(host_key)); |
5260325f | 612 | if (!read_yes_or_no(prompt, -1)) |
613 | fatal("Aborted by user!\n"); | |
614 | } | |
7c49df64 | 615 | if (options.check_host_ip && ip_status == HOST_NEW) { |
5260325f | 616 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); |
617 | hostp = hostline; | |
618 | } else | |
619 | hostp = host; | |
620 | ||
621 | /* If not in strict mode, add the key automatically to the local known_hosts file. */ | |
a306f2dd | 622 | if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) |
5260325f | 623 | log("Failed to add the host to the list of known hosts (%.500s).", |
a306f2dd | 624 | user_hostfile); |
5260325f | 625 | else |
1d1ffb87 | 626 | log("Warning: Permanently added '%.200s' (%s) to the list of known hosts.", |
627 | hostp, type); | |
5260325f | 628 | break; |
629 | case HOST_CHANGED: | |
630 | if (options.check_host_ip && host_ip_differ) { | |
631 | char *msg; | |
632 | if (ip_status == HOST_NEW) | |
633 | msg = "is unknown"; | |
634 | else if (ip_status == HOST_OK) | |
635 | msg = "is unchanged"; | |
636 | else | |
637 | msg = "has a different value"; | |
638 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
639 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
640 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1d1ffb87 | 641 | error("The %s host key for %s has changed,", type, host); |
5260325f | 642 | error("and the key for the according IP address %s", ip); |
643 | error("%s. This could either mean that", msg); | |
644 | error("DNS SPOOFING is happening or the IP address for the host"); | |
1e3b8b07 | 645 | error("and its host key have changed at the same time."); |
7c49df64 | 646 | if (ip_status != HOST_NEW) |
1e3b8b07 | 647 | error("Offending key for IP in %s:%d", ip_file, ip_line); |
5260325f | 648 | } |
649 | /* The host key has changed. */ | |
650 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
ae2f7af7 | 651 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); |
5260325f | 652 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
653 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
654 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
1d1ffb87 | 655 | error("It is also possible that the %s host key has just been changed.", type); |
8abcdba4 | 656 | error("The fingerprint for the %s key sent by the remote host is\n%s.", |
657 | type, key_fingerprint(host_key)); | |
5260325f | 658 | error("Please contact your system administrator."); |
659 | error("Add correct host key in %.100s to get rid of this message.", | |
8abcdba4 | 660 | user_hostfile); |
1e3b8b07 | 661 | error("Offending key in %s:%d", host_file, host_line); |
5260325f | 662 | |
aa3378df | 663 | /* |
664 | * If strict host key checking is in use, the user will have | |
665 | * to edit the key manually and we can only abort. | |
666 | */ | |
5260325f | 667 | if (options.strict_host_key_checking) |
1d1ffb87 | 668 | fatal("%s host key for %.200s has changed and you have requested strict checking.", type, host); |
5260325f | 669 | |
aa3378df | 670 | /* |
671 | * If strict host key checking has not been requested, allow | |
672 | * the connection but without password authentication or | |
673 | * agent forwarding. | |
674 | */ | |
5260325f | 675 | if (options.password_authentication) { |
676 | error("Password authentication is disabled to avoid trojan horses."); | |
677 | options.password_authentication = 0; | |
678 | } | |
679 | if (options.forward_agent) { | |
680 | error("Agent forwarding is disabled to avoid trojan horses."); | |
681 | options.forward_agent = 0; | |
682 | } | |
0b6fbf03 | 683 | if (options.forward_x11) { |
684 | error("X11 forwarding is disabled to avoid trojan horses."); | |
685 | options.forward_x11 = 0; | |
686 | } | |
687 | if (options.num_local_forwards > 0 || options.num_remote_forwards > 0) { | |
688 | error("Port forwarding is disabled to avoid trojan horses."); | |
689 | options.num_local_forwards = options.num_remote_forwards = 0; | |
690 | } | |
aa3378df | 691 | /* |
692 | * XXX Should permit the user to change to use the new id. | |
693 | * This could be done by converting the host key to an | |
694 | * identifying sentence, tell that the host identifies itself | |
695 | * by that sentence, and ask the user if he/she whishes to | |
696 | * accept the authentication. | |
697 | */ | |
5260325f | 698 | break; |
699 | } | |
0b6fbf03 | 700 | |
7c49df64 | 701 | if (options.check_host_ip && host_status != HOST_CHANGED && |
702 | ip_status == HOST_CHANGED) { | |
703 | log("Warning: the %s host key for '%.200s' " | |
704 | "differs from the key for the IP address '%.30s'", | |
705 | type, host, ip); | |
706 | if (host_status == HOST_OK) | |
707 | log("Matching host key in %s:%d", host_file, host_line); | |
708 | log("Offending key for IP in %s:%d", ip_file, ip_line); | |
709 | if (options.strict_host_key_checking == 1) { | |
710 | fatal("Exiting, you have requested strict checking."); | |
711 | } else if (options.strict_host_key_checking == 2) { | |
712 | if (!read_yes_or_no("Continue?", -1)) | |
713 | fatal("Aborted by user!\n"); | |
714 | } | |
715 | } | |
716 | ||
0b6fbf03 | 717 | xfree(ip); |
95f1eccc | 718 | } |
719 | ||
8ce64345 | 720 | /* |
a306f2dd | 721 | * Starts a dialog with the server, and authenticates the current user on the |
722 | * server. This does not need any extra privileges. The basic connection | |
723 | * to the server must already have been established before this is called. | |
724 | * If login fails, this function prints an error and never returns. | |
725 | * This function does not require super-user privileges. | |
8ce64345 | 726 | */ |
727 | void | |
a306f2dd | 728 | ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost, |
729 | struct sockaddr *hostaddr, uid_t original_real_uid) | |
8ce64345 | 730 | { |
8ce64345 | 731 | struct passwd *pw; |
a306f2dd | 732 | char *host, *cp; |
8ce64345 | 733 | char *server_user, *local_user; |
8ce64345 | 734 | |
8ce64345 | 735 | /* Get local user name. Use it as server user if no user name was given. */ |
736 | pw = getpwuid(original_real_uid); | |
737 | if (!pw) | |
14a9a859 | 738 | fatal("User id %u not found from user database.", original_real_uid); |
8ce64345 | 739 | local_user = xstrdup(pw->pw_name); |
740 | server_user = options.user ? options.user : local_user; | |
741 | ||
7b2ea3a1 | 742 | /* Convert the user-supplied hostname into all lowercase. */ |
743 | host = xstrdup(orighost); | |
744 | for (cp = host; *cp; cp++) | |
745 | if (isupper(*cp)) | |
746 | *cp = tolower(*cp); | |
747 | ||
748 | /* Exchange protocol version identification strings with the server. */ | |
749 | ssh_exchange_identification(); | |
750 | ||
751 | /* Put the connection into non-blocking mode. */ | |
752 | packet_set_nonblocking(); | |
753 | ||
7b2ea3a1 | 754 | /* key exchange */ |
7b2ea3a1 | 755 | /* authenticate user */ |
8ce64345 | 756 | if (compat20) { |
757 | ssh_kex2(host, hostaddr); | |
a306f2dd | 758 | ssh_userauth2(server_user, host); |
8ce64345 | 759 | } else { |
8ce64345 | 760 | ssh_kex(host, hostaddr); |
a306f2dd | 761 | ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key); |
8ce64345 | 762 | } |
7b2ea3a1 | 763 | } |