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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" | |
9616313f | 16 | RCSID("$OpenBSD: sshconnect.c,v 1.89 2001/01/04 22:41:03 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. */ | |
30228d7c | 119 | execv(_PATH_BSHELL, argv); |
120 | perror(_PATH_BSHELL); | |
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 | { |
48e671d5 | 190 | int sock = -1, attempt; |
5260325f | 191 | struct servent *sp; |
48e671d5 | 192 | struct addrinfo hints, *ai, *aitop; |
193 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
194 | int gaierr; | |
5260325f | 195 | struct linger linger; |
196 | ||
14a9a859 | 197 | debug("ssh_connect: getuid %u geteuid %u anon %d", |
198 | (u_int) getuid(), (u_int) geteuid(), anonymous); | |
5260325f | 199 | |
200 | /* Get default port if port has not been set. */ | |
201 | if (port == 0) { | |
202 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
203 | if (sp) | |
204 | port = ntohs(sp->s_port); | |
205 | else | |
206 | port = SSH_DEFAULT_PORT; | |
8efc0c15 | 207 | } |
5260325f | 208 | /* If a proxy command is given, connect using it. */ |
209 | if (proxy_command != NULL) | |
210 | return ssh_proxy_connect(host, port, original_real_uid, proxy_command); | |
211 | ||
212 | /* No proxy command. */ | |
213 | ||
48e671d5 | 214 | memset(&hints, 0, sizeof(hints)); |
215 | hints.ai_family = IPv4or6; | |
216 | hints.ai_socktype = SOCK_STREAM; | |
217 | snprintf(strport, sizeof strport, "%d", port); | |
218 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) | |
219 | fatal("%s: %.100s: %s", __progname, host, | |
220 | gai_strerror(gaierr)); | |
5260325f | 221 | |
95f1eccc | 222 | /* |
223 | * Try to connect several times. On some machines, the first time | |
224 | * will sometimes fail. In general socket code appears to behave | |
225 | * quite magically on many machines. | |
226 | */ | |
5260325f | 227 | for (attempt = 0; attempt < connection_attempts; attempt++) { |
228 | if (attempt > 0) | |
229 | debug("Trying again..."); | |
230 | ||
48e671d5 | 231 | /* Loop through addresses for this host, and try each one in |
6ae2364d | 232 | sequence until the connection succeeds. */ |
48e671d5 | 233 | for (ai = aitop; ai; ai = ai->ai_next) { |
234 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
235 | continue; | |
236 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
237 | ntop, sizeof(ntop), strport, sizeof(strport), | |
238 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
239 | error("ssh_connect: getnameinfo failed"); | |
240 | continue; | |
241 | } | |
242 | debug("Connecting to %.200s [%.100s] port %s.", | |
243 | host, ntop, strport); | |
244 | ||
245 | /* Create a socket for connecting. */ | |
6ae2364d | 246 | sock = ssh_create_socket(original_real_uid, |
3c62e7eb | 247 | #ifdef HAVE_CYGWIN |
fa08c86b | 248 | !anonymous, |
3c62e7eb | 249 | #else |
fa08c86b | 250 | !anonymous && geteuid() == 0, |
3c62e7eb | 251 | #endif |
48e671d5 | 252 | ai->ai_family); |
253 | if (sock < 0) | |
254 | continue; | |
255 | ||
256 | /* Connect to the host. We use the user's uid in the | |
257 | * hope that it will help with tcp_wrappers showing | |
258 | * the remote uid as root. | |
aa3378df | 259 | */ |
5260325f | 260 | temporarily_use_uid(original_real_uid); |
48e671d5 | 261 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { |
262 | /* Successful connection. */ | |
3d1a1654 | 263 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); |
5260325f | 264 | restore_uid(); |
265 | break; | |
48e671d5 | 266 | } else { |
5260325f | 267 | debug("connect: %.100s", strerror(errno)); |
268 | restore_uid(); | |
aa3378df | 269 | /* |
270 | * Close the failed socket; there appear to | |
271 | * be some problems when reusing a socket for | |
272 | * which connect() has already returned an | |
273 | * error. | |
274 | */ | |
5260325f | 275 | shutdown(sock, SHUT_RDWR); |
276 | close(sock); | |
277 | } | |
8efc0c15 | 278 | } |
48e671d5 | 279 | if (ai) |
280 | break; /* Successful connection. */ | |
8efc0c15 | 281 | |
5260325f | 282 | /* Sleep a moment before retrying. */ |
283 | sleep(1); | |
284 | } | |
48e671d5 | 285 | |
286 | freeaddrinfo(aitop); | |
287 | ||
5260325f | 288 | /* Return failure if we didn't get a successful connection. */ |
289 | if (attempt >= connection_attempts) | |
290 | return 0; | |
8efc0c15 | 291 | |
5260325f | 292 | debug("Connection established."); |
8efc0c15 | 293 | |
aa3378df | 294 | /* |
295 | * Set socket options. We would like the socket to disappear as soon | |
296 | * as it has been closed for whatever reason. | |
297 | */ | |
298 | /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 299 | linger.l_onoff = 1; |
300 | linger.l_linger = 5; | |
301 | setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
8efc0c15 | 302 | |
5260325f | 303 | /* Set the connection. */ |
304 | packet_set_connection(sock, sock); | |
8efc0c15 | 305 | |
5260325f | 306 | return 1; |
8efc0c15 | 307 | } |
308 | ||
5260325f | 309 | /* |
310 | * Waits for the server identification string, and sends our own | |
311 | * identification string. | |
312 | */ | |
313 | void | |
314 | ssh_exchange_identification() | |
8efc0c15 | 315 | { |
5260325f | 316 | char buf[256], remote_version[256]; /* must be same size! */ |
a8be9f80 | 317 | int remote_major, remote_minor, i, mismatch; |
5260325f | 318 | int connection_in = packet_get_connection_in(); |
319 | int connection_out = packet_get_connection_out(); | |
fa08c86b | 320 | int minor1 = PROTOCOL_MINOR_1; |
5260325f | 321 | |
322 | /* Read other side\'s version identification. */ | |
38c295d6 | 323 | for (;;) { |
324 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
325 | int len = atomicio(read, connection_in, &buf[i], 1); | |
326 | if (len < 0) | |
327 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); | |
328 | if (len != 1) | |
329 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
330 | if (buf[i] == '\r') { | |
331 | buf[i] = '\n'; | |
332 | buf[i + 1] = 0; | |
333 | continue; /**XXX wait for \n */ | |
334 | } | |
335 | if (buf[i] == '\n') { | |
336 | buf[i + 1] = 0; | |
337 | break; | |
338 | } | |
5260325f | 339 | } |
38c295d6 | 340 | buf[sizeof(buf) - 1] = 0; |
341 | if (strncmp(buf, "SSH-", 4) == 0) | |
5260325f | 342 | break; |
38c295d6 | 343 | debug("ssh_exchange_identification: %s", buf); |
8efc0c15 | 344 | } |
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."); | |
fa08c86b | 374 | } else if (remote_minor == 3 || remote_minor == 4) { |
a8be9f80 | 375 | /* We speak 1.3, too. */ |
376 | enable_compat13(); | |
fa08c86b | 377 | minor1 = 3; |
a8be9f80 | 378 | if (options.forward_agent) { |
379 | log("Agent forwarding disabled for protocol 1.3"); | |
380 | options.forward_agent = 0; | |
381 | } | |
382 | } | |
383 | break; | |
384 | case 2: | |
385 | if (options.protocol & SSH_PROTO_2) { | |
386 | enable_compat20(); | |
387 | break; | |
388 | } | |
389 | /* FALLTHROUGH */ | |
6ae2364d | 390 | default: |
a8be9f80 | 391 | mismatch = 1; |
392 | break; | |
8efc0c15 | 393 | } |
a8be9f80 | 394 | if (mismatch) |
5260325f | 395 | fatal("Protocol major versions differ: %d vs. %d", |
a8be9f80 | 396 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
397 | remote_major); | |
a306f2dd | 398 | if (compat20) |
399 | packet_set_ssh2_format(); | |
5260325f | 400 | /* Send our own protocol version identification. */ |
401 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
a8be9f80 | 402 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
fa08c86b | 403 | compat20 ? PROTOCOL_MINOR_2 : minor1, |
8ce64345 | 404 | SSH_VERSION); |
a408af76 | 405 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) |
5260325f | 406 | fatal("write: %.100s", strerror(errno)); |
8ce64345 | 407 | client_version_string = xstrdup(buf); |
408 | chop(client_version_string); | |
409 | chop(server_version_string); | |
410 | debug("Local version string %.100s", client_version_string); | |
8efc0c15 | 411 | } |
412 | ||
5260325f | 413 | int |
414 | read_yes_or_no(const char *prompt, int defval) | |
8efc0c15 | 415 | { |
5260325f | 416 | char buf[1024]; |
417 | FILE *f; | |
418 | int retval = -1; | |
419 | ||
7c49df64 | 420 | if (isatty(STDIN_FILENO)) |
5260325f | 421 | f = stdin; |
422 | else | |
423 | f = fopen("/dev/tty", "rw"); | |
424 | ||
425 | if (f == NULL) | |
426 | return 0; | |
427 | ||
428 | fflush(stdout); | |
429 | ||
430 | while (1) { | |
431 | fprintf(stderr, "%s", prompt); | |
432 | if (fgets(buf, sizeof(buf), f) == NULL) { | |
433 | /* Print a newline (the prompt probably didn\'t have one). */ | |
434 | fprintf(stderr, "\n"); | |
435 | strlcpy(buf, "no", sizeof buf); | |
436 | } | |
437 | /* Remove newline from response. */ | |
438 | if (strchr(buf, '\n')) | |
439 | *strchr(buf, '\n') = 0; | |
440 | ||
441 | if (buf[0] == 0) | |
442 | retval = defval; | |
443 | if (strcmp(buf, "yes") == 0) | |
444 | retval = 1; | |
188adeb2 | 445 | else if (strcmp(buf, "no") == 0) |
5260325f | 446 | retval = 0; |
188adeb2 | 447 | else |
448 | fprintf(stderr, "Please type 'yes' or 'no'.\n"); | |
5260325f | 449 | |
450 | if (retval != -1) { | |
451 | if (f != stdin) | |
452 | fclose(f); | |
453 | return retval; | |
454 | } | |
8efc0c15 | 455 | } |
8efc0c15 | 456 | } |
457 | ||
5260325f | 458 | /* |
95f1eccc | 459 | * check whether the supplied host key is valid, return only if ok. |
5260325f | 460 | */ |
95f1eccc | 461 | |
5260325f | 462 | void |
a306f2dd | 463 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, |
464 | const char *user_hostfile, const char *system_hostfile) | |
8efc0c15 | 465 | { |
4fe2af09 | 466 | Key *file_key; |
1d1ffb87 | 467 | char *type = key_type(host_key); |
95f1eccc | 468 | char *ip = NULL; |
5260325f | 469 | char hostline[1000], *hostp; |
5260325f | 470 | HostStatus host_status; |
471 | HostStatus ip_status; | |
48e671d5 | 472 | int local = 0, host_ip_differ = 0; |
20af321f | 473 | int salen; |
48e671d5 | 474 | char ntop[NI_MAXHOST]; |
7c49df64 | 475 | int host_line, ip_line; |
1e3b8b07 | 476 | const char *host_file = NULL, *ip_file = NULL; |
48e671d5 | 477 | |
478 | /* | |
479 | * Force accepting of the host key for loopback/localhost. The | |
480 | * problem is that if the home directory is NFS-mounted to multiple | |
481 | * machines, localhost will refer to a different machine in each of | |
482 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
483 | * essentially disables host authentication for localhost; however, | |
484 | * this is probably not a real problem. | |
485 | */ | |
a306f2dd | 486 | /** hostaddr == 0! */ |
48e671d5 | 487 | switch (hostaddr->sa_family) { |
488 | case AF_INET: | |
489 | local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; | |
20af321f | 490 | salen = sizeof(struct sockaddr_in); |
48e671d5 | 491 | break; |
492 | case AF_INET6: | |
493 | local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
20af321f | 494 | salen = sizeof(struct sockaddr_in6); |
48e671d5 | 495 | break; |
496 | default: | |
497 | local = 0; | |
20af321f | 498 | salen = sizeof(struct sockaddr_storage); |
48e671d5 | 499 | break; |
500 | } | |
7c49df64 | 501 | if (local && options.host_key_alias == NULL) { |
502 | debug("Forcing accepting of host key for " | |
503 | "loopback/localhost."); | |
504 | return; | |
48e671d5 | 505 | } |
5260325f | 506 | |
57112b5a | 507 | /* |
7c49df64 | 508 | * We don't have the remote ip-address for connections |
509 | * using a proxy command | |
510 | */ | |
511 | if (options.proxy_command == NULL) { | |
512 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), | |
513 | NULL, 0, NI_NUMERICHOST) != 0) | |
514 | fatal("check_host_key: getnameinfo failed"); | |
515 | ip = xstrdup(ntop); | |
516 | } else { | |
517 | ip = xstrdup("<no hostip for proxy command>"); | |
518 | } | |
519 | /* | |
520 | * Turn off check_host_ip if the connection is to localhost, via proxy | |
521 | * command or if we don't have a hostname to compare with | |
57112b5a | 522 | */ |
7c49df64 | 523 | if (options.check_host_ip && |
524 | (local || strcmp(host, ip) == 0 || options.proxy_command != NULL)) | |
57112b5a | 525 | options.check_host_ip = 0; |
526 | ||
8abcdba4 | 527 | /* |
7c49df64 | 528 | * Allow the user to record the key under a different name. This is |
8abcdba4 | 529 | * useful for ssh tunneling over forwarded connections or if you run |
7c49df64 | 530 | * multiple sshd's on different ports on the same machine. |
8abcdba4 | 531 | */ |
532 | if (options.host_key_alias != NULL) { | |
533 | host = options.host_key_alias; | |
534 | debug("using hostkeyalias: %s", host); | |
535 | } | |
536 | ||
95f1eccc | 537 | /* |
538 | * Store the host key from the known host file in here so that we can | |
539 | * compare it with the key for the IP address. | |
540 | */ | |
4fe2af09 | 541 | file_key = key_new(host_key->type); |
5260325f | 542 | |
aa3378df | 543 | /* |
544 | * Check if the host key is present in the user\'s list of known | |
545 | * hosts or in the systemwide list. | |
546 | */ | |
1e3b8b07 | 547 | host_file = user_hostfile; |
548 | host_status = check_host_in_hostfile(host_file, host, host_key, file_key, &host_line); | |
549 | if (host_status == HOST_NEW) { | |
550 | host_file = system_hostfile; | |
551 | host_status = check_host_in_hostfile(host_file, host, host_key, file_key, &host_line); | |
552 | } | |
aa3378df | 553 | /* |
554 | * Also perform check for the ip address, skip the check if we are | |
555 | * localhost or the hostname was an ip address to begin with | |
556 | */ | |
7c49df64 | 557 | if (options.check_host_ip) { |
4fe2af09 | 558 | Key *ip_key = key_new(host_key->type); |
5260325f | 559 | |
1e3b8b07 | 560 | ip_file = user_hostfile; |
561 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, ip_key, &ip_line); | |
562 | if (ip_status == HOST_NEW) { | |
563 | ip_file = system_hostfile; | |
564 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, ip_key, &ip_line); | |
565 | } | |
5260325f | 566 | if (host_status == HOST_CHANGED && |
4fe2af09 | 567 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) |
5260325f | 568 | host_ip_differ = 1; |
569 | ||
4fe2af09 | 570 | key_free(ip_key); |
5260325f | 571 | } else |
572 | ip_status = host_status; | |
573 | ||
4fe2af09 | 574 | key_free(file_key); |
5260325f | 575 | |
576 | switch (host_status) { | |
577 | case HOST_OK: | |
578 | /* The host is known and the key matches. */ | |
1d1ffb87 | 579 | debug("Host '%.200s' is known and matches the %s host key.", |
580 | host, type); | |
1e3b8b07 | 581 | debug("Found key in %s:%d", host_file, host_line); |
7c49df64 | 582 | if (options.check_host_ip && ip_status == HOST_NEW) { |
583 | if (!add_host_to_hostfile(user_hostfile, ip, host_key)) | |
584 | log("Failed to add the %s host key for IP address '%.30s' to the list of known hosts (%.30s).", | |
585 | type, ip, user_hostfile); | |
586 | else | |
587 | log("Warning: Permanently added the %s host key for IP address '%.30s' to the list of known hosts.", | |
588 | type, ip); | |
5260325f | 589 | } |
590 | break; | |
591 | case HOST_NEW: | |
592 | /* The host is new. */ | |
593 | if (options.strict_host_key_checking == 1) { | |
594 | /* User has requested strict host key checking. We will not add the host key | |
595 | automatically. The only alternative left is to abort. */ | |
1d1ffb87 | 596 | fatal("No %s host key is known for %.200s and you have requested strict checking.", type, host); |
5260325f | 597 | } else if (options.strict_host_key_checking == 2) { |
598 | /* The default */ | |
599 | char prompt[1024]; | |
5260325f | 600 | snprintf(prompt, sizeof(prompt), |
0b6fbf03 | 601 | "The authenticity of host '%.200s (%s)' can't be established.\n" |
1d1ffb87 | 602 | "%s key fingerprint is %s.\n" |
a408af76 | 603 | "Are you sure you want to continue connecting (yes/no)? ", |
8abcdba4 | 604 | host, ip, type, key_fingerprint(host_key)); |
5260325f | 605 | if (!read_yes_or_no(prompt, -1)) |
606 | fatal("Aborted by user!\n"); | |
607 | } | |
7c49df64 | 608 | if (options.check_host_ip && ip_status == HOST_NEW) { |
5260325f | 609 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); |
610 | hostp = hostline; | |
611 | } else | |
612 | hostp = host; | |
613 | ||
614 | /* If not in strict mode, add the key automatically to the local known_hosts file. */ | |
a306f2dd | 615 | if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) |
5260325f | 616 | log("Failed to add the host to the list of known hosts (%.500s).", |
a306f2dd | 617 | user_hostfile); |
5260325f | 618 | else |
1d1ffb87 | 619 | log("Warning: Permanently added '%.200s' (%s) to the list of known hosts.", |
620 | hostp, type); | |
5260325f | 621 | break; |
622 | case HOST_CHANGED: | |
623 | if (options.check_host_ip && host_ip_differ) { | |
624 | char *msg; | |
625 | if (ip_status == HOST_NEW) | |
626 | msg = "is unknown"; | |
627 | else if (ip_status == HOST_OK) | |
628 | msg = "is unchanged"; | |
629 | else | |
630 | msg = "has a different value"; | |
631 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
632 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
633 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1d1ffb87 | 634 | error("The %s host key for %s has changed,", type, host); |
5260325f | 635 | error("and the key for the according IP address %s", ip); |
636 | error("%s. This could either mean that", msg); | |
637 | error("DNS SPOOFING is happening or the IP address for the host"); | |
1e3b8b07 | 638 | error("and its host key have changed at the same time."); |
7c49df64 | 639 | if (ip_status != HOST_NEW) |
1e3b8b07 | 640 | error("Offending key for IP in %s:%d", ip_file, ip_line); |
5260325f | 641 | } |
642 | /* The host key has changed. */ | |
643 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
ae2f7af7 | 644 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); |
5260325f | 645 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
646 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
647 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
1d1ffb87 | 648 | error("It is also possible that the %s host key has just been changed.", type); |
8abcdba4 | 649 | error("The fingerprint for the %s key sent by the remote host is\n%s.", |
650 | type, key_fingerprint(host_key)); | |
5260325f | 651 | error("Please contact your system administrator."); |
652 | error("Add correct host key in %.100s to get rid of this message.", | |
8abcdba4 | 653 | user_hostfile); |
1e3b8b07 | 654 | error("Offending key in %s:%d", host_file, host_line); |
5260325f | 655 | |
aa3378df | 656 | /* |
657 | * If strict host key checking is in use, the user will have | |
658 | * to edit the key manually and we can only abort. | |
659 | */ | |
5260325f | 660 | if (options.strict_host_key_checking) |
1d1ffb87 | 661 | fatal("%s host key for %.200s has changed and you have requested strict checking.", type, host); |
5260325f | 662 | |
aa3378df | 663 | /* |
664 | * If strict host key checking has not been requested, allow | |
665 | * the connection but without password authentication or | |
666 | * agent forwarding. | |
667 | */ | |
5260325f | 668 | if (options.password_authentication) { |
669 | error("Password authentication is disabled to avoid trojan horses."); | |
670 | options.password_authentication = 0; | |
671 | } | |
672 | if (options.forward_agent) { | |
673 | error("Agent forwarding is disabled to avoid trojan horses."); | |
674 | options.forward_agent = 0; | |
675 | } | |
0b6fbf03 | 676 | if (options.forward_x11) { |
677 | error("X11 forwarding is disabled to avoid trojan horses."); | |
678 | options.forward_x11 = 0; | |
679 | } | |
680 | if (options.num_local_forwards > 0 || options.num_remote_forwards > 0) { | |
681 | error("Port forwarding is disabled to avoid trojan horses."); | |
682 | options.num_local_forwards = options.num_remote_forwards = 0; | |
683 | } | |
aa3378df | 684 | /* |
685 | * XXX Should permit the user to change to use the new id. | |
686 | * This could be done by converting the host key to an | |
687 | * identifying sentence, tell that the host identifies itself | |
688 | * by that sentence, and ask the user if he/she whishes to | |
689 | * accept the authentication. | |
690 | */ | |
5260325f | 691 | break; |
692 | } | |
0b6fbf03 | 693 | |
7c49df64 | 694 | if (options.check_host_ip && host_status != HOST_CHANGED && |
695 | ip_status == HOST_CHANGED) { | |
696 | log("Warning: the %s host key for '%.200s' " | |
697 | "differs from the key for the IP address '%.30s'", | |
698 | type, host, ip); | |
699 | if (host_status == HOST_OK) | |
700 | log("Matching host key in %s:%d", host_file, host_line); | |
701 | log("Offending key for IP in %s:%d", ip_file, ip_line); | |
702 | if (options.strict_host_key_checking == 1) { | |
703 | fatal("Exiting, you have requested strict checking."); | |
704 | } else if (options.strict_host_key_checking == 2) { | |
705 | if (!read_yes_or_no("Continue?", -1)) | |
706 | fatal("Aborted by user!\n"); | |
707 | } | |
708 | } | |
709 | ||
0b6fbf03 | 710 | xfree(ip); |
95f1eccc | 711 | } |
712 | ||
8ce64345 | 713 | /* |
a306f2dd | 714 | * Starts a dialog with the server, and authenticates the current user on the |
715 | * server. This does not need any extra privileges. The basic connection | |
716 | * to the server must already have been established before this is called. | |
717 | * If login fails, this function prints an error and never returns. | |
718 | * This function does not require super-user privileges. | |
8ce64345 | 719 | */ |
720 | void | |
a306f2dd | 721 | ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost, |
722 | struct sockaddr *hostaddr, uid_t original_real_uid) | |
8ce64345 | 723 | { |
8ce64345 | 724 | struct passwd *pw; |
a306f2dd | 725 | char *host, *cp; |
8ce64345 | 726 | char *server_user, *local_user; |
8ce64345 | 727 | |
8ce64345 | 728 | /* Get local user name. Use it as server user if no user name was given. */ |
729 | pw = getpwuid(original_real_uid); | |
730 | if (!pw) | |
14a9a859 | 731 | fatal("User id %u not found from user database.", original_real_uid); |
8ce64345 | 732 | local_user = xstrdup(pw->pw_name); |
733 | server_user = options.user ? options.user : local_user; | |
734 | ||
7b2ea3a1 | 735 | /* Convert the user-supplied hostname into all lowercase. */ |
736 | host = xstrdup(orighost); | |
737 | for (cp = host; *cp; cp++) | |
738 | if (isupper(*cp)) | |
739 | *cp = tolower(*cp); | |
740 | ||
741 | /* Exchange protocol version identification strings with the server. */ | |
742 | ssh_exchange_identification(); | |
743 | ||
744 | /* Put the connection into non-blocking mode. */ | |
745 | packet_set_nonblocking(); | |
746 | ||
7b2ea3a1 | 747 | /* key exchange */ |
7b2ea3a1 | 748 | /* authenticate user */ |
8ce64345 | 749 | if (compat20) { |
750 | ssh_kex2(host, hostaddr); | |
a306f2dd | 751 | ssh_userauth2(server_user, host); |
8ce64345 | 752 | } else { |
8ce64345 | 753 | ssh_kex(host, hostaddr); |
a306f2dd | 754 | ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key); |
8ce64345 | 755 | } |
7b2ea3a1 | 756 | } |