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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" | |
3e131a6d | 16 | RCSID("$OpenBSD: sshconnect.c,v 1.139 2003/04/14 14:17:50 markus Exp $"); |
8efc0c15 | 17 | |
8ce64345 | 18 | #include <openssl/bn.h> |
a306f2dd | 19 | |
42f11eb2 | 20 | #include "ssh.h" |
8efc0c15 | 21 | #include "xmalloc.h" |
22 | #include "rsa.h" | |
8ce64345 | 23 | #include "buffer.h" |
8efc0c15 | 24 | #include "packet.h" |
8efc0c15 | 25 | #include "uidswap.h" |
26 | #include "compat.h" | |
4fe2af09 | 27 | #include "key.h" |
a306f2dd | 28 | #include "sshconnect.h" |
4fe2af09 | 29 | #include "hostfile.h" |
42f11eb2 | 30 | #include "log.h" |
31 | #include "readconf.h" | |
32 | #include "atomicio.h" | |
33 | #include "misc.h" | |
616a6b93 | 34 | #include "readpass.h" |
8efc0c15 | 35 | |
a306f2dd | 36 | char *client_version_string = NULL; |
37 | char *server_version_string = NULL; | |
8ce64345 | 38 | |
3fb156df | 39 | /* import */ |
57112b5a | 40 | extern Options options; |
48e671d5 | 41 | extern char *__progname; |
3fb156df | 42 | extern uid_t original_real_uid; |
43 | extern uid_t original_effective_uid; | |
6939bbd4 | 44 | extern pid_t proxy_command_pid; |
57112b5a | 45 | |
a704dd54 | 46 | #ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */ |
47 | #define INET6_ADDRSTRLEN 46 | |
48 | #endif | |
49 | ||
8a48a7ef | 50 | static int show_other_keys(const char *, Key *); |
51 | ||
5260325f | 52 | /* |
53 | * Connect to the given ssh server using a proxy command. | |
54 | */ | |
396c147e | 55 | static int |
3fb156df | 56 | ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) |
8efc0c15 | 57 | { |
5260325f | 58 | Buffer command; |
59 | const char *cp; | |
60 | char *command_string; | |
61 | int pin[2], pout[2]; | |
9da5c3c9 | 62 | pid_t pid; |
48e671d5 | 63 | char strport[NI_MAXSERV]; |
5260325f | 64 | |
65 | /* Convert the port number into a string. */ | |
48e671d5 | 66 | snprintf(strport, sizeof strport, "%hu", port); |
5260325f | 67 | |
6939bbd4 | 68 | /* |
69 | * Build the final command string in the buffer by making the | |
70 | * appropriate substitutions to the given proxy command. | |
71 | * | |
72 | * Use "exec" to avoid "sh -c" processes on some platforms | |
73 | * (e.g. Solaris) | |
74 | */ | |
5260325f | 75 | buffer_init(&command); |
6939bbd4 | 76 | buffer_append(&command, "exec ", 5); |
77 | ||
5260325f | 78 | for (cp = proxy_command; *cp; cp++) { |
79 | if (cp[0] == '%' && cp[1] == '%') { | |
80 | buffer_append(&command, "%", 1); | |
81 | cp++; | |
82 | continue; | |
83 | } | |
84 | if (cp[0] == '%' && cp[1] == 'h') { | |
85 | buffer_append(&command, host, strlen(host)); | |
86 | cp++; | |
87 | continue; | |
88 | } | |
89 | if (cp[0] == '%' && cp[1] == 'p') { | |
48e671d5 | 90 | buffer_append(&command, strport, strlen(strport)); |
5260325f | 91 | cp++; |
92 | continue; | |
93 | } | |
94 | buffer_append(&command, cp, 1); | |
8efc0c15 | 95 | } |
5260325f | 96 | buffer_append(&command, "\0", 1); |
97 | ||
98 | /* Get the final command string. */ | |
99 | command_string = buffer_ptr(&command); | |
100 | ||
101 | /* Create pipes for communicating with the proxy. */ | |
102 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
103 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
184eed6a | 104 | strerror(errno)); |
5260325f | 105 | |
106 | debug("Executing proxy command: %.500s", command_string); | |
107 | ||
108 | /* Fork and execute the proxy command. */ | |
109 | if ((pid = fork()) == 0) { | |
110 | char *argv[10]; | |
111 | ||
112 | /* Child. Permanently give up superuser privileges. */ | |
3fb156df | 113 | seteuid(original_real_uid); |
114 | setuid(original_real_uid); | |
5260325f | 115 | |
116 | /* Redirect stdin and stdout. */ | |
117 | close(pin[1]); | |
118 | if (pin[0] != 0) { | |
119 | if (dup2(pin[0], 0) < 0) | |
120 | perror("dup2 stdin"); | |
121 | close(pin[0]); | |
122 | } | |
123 | close(pout[0]); | |
124 | if (dup2(pout[1], 1) < 0) | |
125 | perror("dup2 stdout"); | |
126 | /* Cannot be 1 because pin allocated two descriptors. */ | |
127 | close(pout[1]); | |
128 | ||
129 | /* Stderr is left as it is so that error messages get | |
130 | printed on the user's terminal. */ | |
30228d7c | 131 | argv[0] = _PATH_BSHELL; |
5260325f | 132 | argv[1] = "-c"; |
133 | argv[2] = command_string; | |
134 | argv[3] = NULL; | |
135 | ||
136 | /* Execute the proxy command. Note that we gave up any | |
137 | extra privileges above. */ | |
328654d8 | 138 | execv(argv[0], argv); |
139 | perror(argv[0]); | |
5260325f | 140 | exit(1); |
8efc0c15 | 141 | } |
5260325f | 142 | /* Parent. */ |
143 | if (pid < 0) | |
144 | fatal("fork failed: %.100s", strerror(errno)); | |
6939bbd4 | 145 | else |
146 | proxy_command_pid = pid; /* save pid to clean up later */ | |
5260325f | 147 | |
148 | /* Close child side of the descriptors. */ | |
149 | close(pin[0]); | |
150 | close(pout[1]); | |
151 | ||
152 | /* Free the command name. */ | |
153 | buffer_free(&command); | |
154 | ||
155 | /* Set the connection file descriptors. */ | |
156 | packet_set_connection(pout[0], pin[1]); | |
8efc0c15 | 157 | |
ce773142 | 158 | /* Indicate OK return */ |
159 | return 0; | |
5260325f | 160 | } |
8efc0c15 | 161 | |
5260325f | 162 | /* |
163 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
164 | */ | |
396c147e | 165 | static int |
3e131a6d | 166 | ssh_create_socket(int privileged, struct addrinfo *ai) |
8efc0c15 | 167 | { |
3435f5a6 | 168 | int sock, gaierr; |
169 | struct addrinfo hints, *res; | |
5260325f | 170 | |
aa3378df | 171 | /* |
172 | * If we are running as root and want to connect to a privileged | |
173 | * port, bind our own socket to a privileged port. | |
174 | */ | |
5260325f | 175 | if (privileged) { |
176 | int p = IPPORT_RESERVED - 1; | |
3fb156df | 177 | PRIV_START; |
3e131a6d | 178 | sock = rresvport_af(&p, ai->ai_family); |
3fb156df | 179 | PRIV_END; |
5260325f | 180 | if (sock < 0) |
3e131a6d | 181 | error("rresvport: af=%d %.100s", ai->ai_family, |
182 | strerror(errno)); | |
c8d54615 | 183 | else |
184 | debug("Allocated local port %d.", p); | |
3435f5a6 | 185 | return sock; |
186 | } | |
3e131a6d | 187 | sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); |
3435f5a6 | 188 | if (sock < 0) |
189 | error("socket: %.100s", strerror(errno)); | |
3435f5a6 | 190 | |
191 | /* Bind the socket to an alternative local IP address */ | |
192 | if (options.bind_address == NULL) | |
193 | return sock; | |
194 | ||
195 | memset(&hints, 0, sizeof(hints)); | |
3e131a6d | 196 | hints.ai_family = ai->ai_family; |
197 | hints.ai_socktype = ai->ai_socktype; | |
198 | hints.ai_protocol = ai->ai_protocol; | |
3435f5a6 | 199 | hints.ai_flags = AI_PASSIVE; |
200 | gaierr = getaddrinfo(options.bind_address, "0", &hints, &res); | |
201 | if (gaierr) { | |
202 | error("getaddrinfo: %s: %s", options.bind_address, | |
203 | gai_strerror(gaierr)); | |
204 | close(sock); | |
205 | return -1; | |
206 | } | |
207 | if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { | |
208 | error("bind: %s: %s", options.bind_address, strerror(errno)); | |
209 | close(sock); | |
210 | freeaddrinfo(res); | |
211 | return -1; | |
5260325f | 212 | } |
3435f5a6 | 213 | freeaddrinfo(res); |
5260325f | 214 | return sock; |
8efc0c15 | 215 | } |
216 | ||
5260325f | 217 | /* |
48e671d5 | 218 | * Opens a TCP/IP connection to the remote server on the given host. |
219 | * The address of the remote host will be returned in hostaddr. | |
3fb156df | 220 | * If port is 0, the default port will be used. If needpriv is true, |
5260325f | 221 | * a privileged port will be allocated to make the connection. |
3fb156df | 222 | * This requires super-user privileges if needpriv is true. |
5260325f | 223 | * Connection_attempts specifies the maximum number of tries (one per |
224 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
225 | * and %p substituted for host and port, respectively) to use to contact | |
226 | * the daemon. | |
ce773142 | 227 | * Return values: |
228 | * 0 for OK | |
229 | * ECONNREFUSED if we got a "Connection Refused" by the peer on any address | |
230 | * ECONNABORTED if we failed without a "Connection refused" | |
231 | * Suitable error messages for the connection failure will already have been | |
232 | * printed. | |
5260325f | 233 | */ |
234 | int | |
48e671d5 | 235 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, |
dab89049 | 236 | u_short port, int family, int connection_attempts, |
3fb156df | 237 | int needpriv, const char *proxy_command) |
8efc0c15 | 238 | { |
b5c334cc | 239 | int gaierr; |
240 | int on = 1; | |
48e671d5 | 241 | int sock = -1, attempt; |
48e671d5 | 242 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; |
b5c334cc | 243 | struct addrinfo hints, *ai, *aitop; |
b5c334cc | 244 | struct servent *sp; |
ce773142 | 245 | /* |
246 | * Did we get only other errors than "Connection refused" (which | |
247 | * should block fallback to rsh and similar), or did we get at least | |
248 | * one "Connection refused"? | |
249 | */ | |
250 | int full_failure = 1; | |
5260325f | 251 | |
a77673cc | 252 | debug2("ssh_connect: needpriv %d", needpriv); |
5260325f | 253 | |
254 | /* Get default port if port has not been set. */ | |
255 | if (port == 0) { | |
256 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
257 | if (sp) | |
258 | port = ntohs(sp->s_port); | |
259 | else | |
260 | port = SSH_DEFAULT_PORT; | |
8efc0c15 | 261 | } |
5260325f | 262 | /* If a proxy command is given, connect using it. */ |
263 | if (proxy_command != NULL) | |
3fb156df | 264 | return ssh_proxy_connect(host, port, proxy_command); |
5260325f | 265 | |
266 | /* No proxy command. */ | |
267 | ||
48e671d5 | 268 | memset(&hints, 0, sizeof(hints)); |
dab89049 | 269 | hints.ai_family = family; |
48e671d5 | 270 | hints.ai_socktype = SOCK_STREAM; |
d6133f43 | 271 | snprintf(strport, sizeof strport, "%u", port); |
48e671d5 | 272 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) |
273 | fatal("%s: %.100s: %s", __progname, host, | |
274 | gai_strerror(gaierr)); | |
5260325f | 275 | |
95f1eccc | 276 | /* |
277 | * Try to connect several times. On some machines, the first time | |
278 | * will sometimes fail. In general socket code appears to behave | |
279 | * quite magically on many machines. | |
ce773142 | 280 | */ |
281 | for (attempt = 0; ;) { | |
5260325f | 282 | if (attempt > 0) |
283 | debug("Trying again..."); | |
284 | ||
48e671d5 | 285 | /* Loop through addresses for this host, and try each one in |
6ae2364d | 286 | sequence until the connection succeeds. */ |
48e671d5 | 287 | for (ai = aitop; ai; ai = ai->ai_next) { |
288 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
289 | continue; | |
290 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
291 | ntop, sizeof(ntop), strport, sizeof(strport), | |
292 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
293 | error("ssh_connect: getnameinfo failed"); | |
294 | continue; | |
295 | } | |
296 | debug("Connecting to %.200s [%.100s] port %s.", | |
297 | host, ntop, strport); | |
298 | ||
299 | /* Create a socket for connecting. */ | |
3e131a6d | 300 | sock = ssh_create_socket(needpriv, ai); |
48e671d5 | 301 | if (sock < 0) |
ce773142 | 302 | /* Any error is already output */ |
48e671d5 | 303 | continue; |
304 | ||
48e671d5 | 305 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { |
306 | /* Successful connection. */ | |
cd332296 | 307 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); |
5260325f | 308 | break; |
48e671d5 | 309 | } else { |
ce773142 | 310 | if (errno == ECONNREFUSED) |
311 | full_failure = 0; | |
c750d869 | 312 | debug("connect to address %s port %s: %s", |
313 | ntop, strport, strerror(errno)); | |
aa3378df | 314 | /* |
315 | * Close the failed socket; there appear to | |
316 | * be some problems when reusing a socket for | |
317 | * which connect() has already returned an | |
318 | * error. | |
319 | */ | |
5260325f | 320 | close(sock); |
321 | } | |
8efc0c15 | 322 | } |
48e671d5 | 323 | if (ai) |
324 | break; /* Successful connection. */ | |
8efc0c15 | 325 | |
ce773142 | 326 | attempt++; |
327 | if (attempt >= connection_attempts) | |
328 | break; | |
5260325f | 329 | /* Sleep a moment before retrying. */ |
330 | sleep(1); | |
331 | } | |
48e671d5 | 332 | |
333 | freeaddrinfo(aitop); | |
334 | ||
5260325f | 335 | /* Return failure if we didn't get a successful connection. */ |
9bd68577 | 336 | if (attempt >= connection_attempts) { |
bbe88b6d | 337 | logit("ssh: connect to host %s port %s: %s", |
9bd68577 | 338 | host, strport, strerror(errno)); |
ce773142 | 339 | return full_failure ? ECONNABORTED : ECONNREFUSED; |
9bd68577 | 340 | } |
8efc0c15 | 341 | |
5260325f | 342 | debug("Connection established."); |
8efc0c15 | 343 | |
b5c334cc | 344 | /* Set keepalives if requested. */ |
345 | if (options.keepalives && | |
346 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, | |
347 | sizeof(on)) < 0) | |
348 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
8efc0c15 | 349 | |
5260325f | 350 | /* Set the connection. */ |
351 | packet_set_connection(sock, sock); | |
8efc0c15 | 352 | |
ce773142 | 353 | return 0; |
8efc0c15 | 354 | } |
355 | ||
5260325f | 356 | /* |
357 | * Waits for the server identification string, and sends our own | |
358 | * identification string. | |
359 | */ | |
396c147e | 360 | static void |
5ca51e19 | 361 | ssh_exchange_identification(void) |
8efc0c15 | 362 | { |
5260325f | 363 | char buf[256], remote_version[256]; /* must be same size! */ |
a8be9f80 | 364 | int remote_major, remote_minor, i, mismatch; |
5260325f | 365 | int connection_in = packet_get_connection_in(); |
366 | int connection_out = packet_get_connection_out(); | |
2b87da3b | 367 | int minor1 = PROTOCOL_MINOR_1; |
5260325f | 368 | |
369 | /* Read other side\'s version identification. */ | |
38c295d6 | 370 | for (;;) { |
371 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
372 | int len = atomicio(read, connection_in, &buf[i], 1); | |
373 | if (len < 0) | |
374 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); | |
375 | if (len != 1) | |
376 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
377 | if (buf[i] == '\r') { | |
378 | buf[i] = '\n'; | |
379 | buf[i + 1] = 0; | |
380 | continue; /**XXX wait for \n */ | |
381 | } | |
382 | if (buf[i] == '\n') { | |
383 | buf[i + 1] = 0; | |
384 | break; | |
385 | } | |
5260325f | 386 | } |
38c295d6 | 387 | buf[sizeof(buf) - 1] = 0; |
388 | if (strncmp(buf, "SSH-", 4) == 0) | |
5260325f | 389 | break; |
38c295d6 | 390 | debug("ssh_exchange_identification: %s", buf); |
8efc0c15 | 391 | } |
8ce64345 | 392 | server_version_string = xstrdup(buf); |
5260325f | 393 | |
aa3378df | 394 | /* |
395 | * Check that the versions match. In future this might accept | |
396 | * several versions and set appropriate flags to handle them. | |
397 | */ | |
8ce64345 | 398 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", |
399 | &remote_major, &remote_minor, remote_version) != 3) | |
5260325f | 400 | fatal("Bad remote protocol version identification: '%.100s'", buf); |
401 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
184eed6a | 402 | remote_major, remote_minor, remote_version); |
5260325f | 403 | |
8ce64345 | 404 | compat_datafellows(remote_version); |
a8be9f80 | 405 | mismatch = 0; |
406 | ||
6aacefa7 | 407 | switch (remote_major) { |
a8be9f80 | 408 | case 1: |
409 | if (remote_minor == 99 && | |
410 | (options.protocol & SSH_PROTO_2) && | |
411 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
412 | enable_compat20(); | |
413 | break; | |
5260325f | 414 | } |
a8be9f80 | 415 | if (!(options.protocol & SSH_PROTO_1)) { |
416 | mismatch = 1; | |
417 | break; | |
418 | } | |
419 | if (remote_minor < 3) { | |
420 | fatal("Remote machine has too old SSH software version."); | |
fa08c86b | 421 | } else if (remote_minor == 3 || remote_minor == 4) { |
a8be9f80 | 422 | /* We speak 1.3, too. */ |
423 | enable_compat13(); | |
fa08c86b | 424 | minor1 = 3; |
a8be9f80 | 425 | if (options.forward_agent) { |
bbe88b6d | 426 | logit("Agent forwarding disabled for protocol 1.3"); |
a8be9f80 | 427 | options.forward_agent = 0; |
428 | } | |
429 | } | |
430 | break; | |
431 | case 2: | |
432 | if (options.protocol & SSH_PROTO_2) { | |
433 | enable_compat20(); | |
434 | break; | |
435 | } | |
436 | /* FALLTHROUGH */ | |
6ae2364d | 437 | default: |
a8be9f80 | 438 | mismatch = 1; |
439 | break; | |
8efc0c15 | 440 | } |
a8be9f80 | 441 | if (mismatch) |
5260325f | 442 | fatal("Protocol major versions differ: %d vs. %d", |
a8be9f80 | 443 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
444 | remote_major); | |
5260325f | 445 | /* Send our own protocol version identification. */ |
446 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
a8be9f80 | 447 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
fa08c86b | 448 | compat20 ? PROTOCOL_MINOR_2 : minor1, |
8ce64345 | 449 | SSH_VERSION); |
a408af76 | 450 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) |
5260325f | 451 | fatal("write: %.100s", strerror(errno)); |
8ce64345 | 452 | client_version_string = xstrdup(buf); |
453 | chop(client_version_string); | |
454 | chop(server_version_string); | |
455 | debug("Local version string %.100s", client_version_string); | |
8efc0c15 | 456 | } |
457 | ||
f21032a6 | 458 | /* defaults to 'no' */ |
396c147e | 459 | static int |
a2c92c4a | 460 | confirm(const char *prompt) |
8efc0c15 | 461 | { |
616a6b93 | 462 | const char *msg, *again = "Please type 'yes' or 'no': "; |
463 | char *p; | |
464 | int ret = -1; | |
5260325f | 465 | |
f21032a6 | 466 | if (options.batch_mode) |
467 | return 0; | |
616a6b93 | 468 | for (msg = prompt;;msg = again) { |
469 | p = read_passphrase(msg, RP_ECHO); | |
470 | if (p == NULL || | |
471 | (p[0] == '\0') || (p[0] == '\n') || | |
472 | strncasecmp(p, "no", 2) == 0) | |
473 | ret = 0; | |
f11fe301 | 474 | if (p && strncasecmp(p, "yes", 3) == 0) |
616a6b93 | 475 | ret = 1; |
476 | if (p) | |
477 | xfree(p); | |
478 | if (ret != -1) | |
479 | return ret; | |
8efc0c15 | 480 | } |
8efc0c15 | 481 | } |
482 | ||
5260325f | 483 | /* |
f49bc4f7 | 484 | * check whether the supplied host key is valid, return -1 if the key |
485 | * is not valid. the user_hostfile will not be updated if 'readonly' is true. | |
5260325f | 486 | */ |
396c147e | 487 | static int |
a306f2dd | 488 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, |
f49bc4f7 | 489 | int readonly, const char *user_hostfile, const char *system_hostfile) |
8efc0c15 | 490 | { |
4fe2af09 | 491 | Key *file_key; |
1d1ffb87 | 492 | char *type = key_type(host_key); |
95f1eccc | 493 | char *ip = NULL; |
22138a36 | 494 | char hostline[1000], *hostp, *fp; |
5260325f | 495 | HostStatus host_status; |
496 | HostStatus ip_status; | |
48e671d5 | 497 | int local = 0, host_ip_differ = 0; |
20af321f | 498 | int salen; |
48e671d5 | 499 | char ntop[NI_MAXHOST]; |
616a6b93 | 500 | char msg[1024]; |
8a48a7ef | 501 | int len, host_line, ip_line, has_keys; |
1e3b8b07 | 502 | const char *host_file = NULL, *ip_file = NULL; |
48e671d5 | 503 | |
504 | /* | |
505 | * Force accepting of the host key for loopback/localhost. The | |
506 | * problem is that if the home directory is NFS-mounted to multiple | |
507 | * machines, localhost will refer to a different machine in each of | |
508 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
509 | * essentially disables host authentication for localhost; however, | |
510 | * this is probably not a real problem. | |
511 | */ | |
a306f2dd | 512 | /** hostaddr == 0! */ |
48e671d5 | 513 | switch (hostaddr->sa_family) { |
514 | case AF_INET: | |
f49bc4f7 | 515 | local = (ntohl(((struct sockaddr_in *)hostaddr)-> |
20a11d35 | 516 | sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; |
20af321f | 517 | salen = sizeof(struct sockaddr_in); |
48e671d5 | 518 | break; |
519 | case AF_INET6: | |
f49bc4f7 | 520 | local = IN6_IS_ADDR_LOOPBACK( |
521 | &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
20af321f | 522 | salen = sizeof(struct sockaddr_in6); |
48e671d5 | 523 | break; |
524 | default: | |
525 | local = 0; | |
20af321f | 526 | salen = sizeof(struct sockaddr_storage); |
48e671d5 | 527 | break; |
528 | } | |
8bbc048a | 529 | if (options.no_host_authentication_for_localhost == 1 && local && |
530 | options.host_key_alias == NULL) { | |
7c49df64 | 531 | debug("Forcing accepting of host key for " |
532 | "loopback/localhost."); | |
f49bc4f7 | 533 | return 0; |
48e671d5 | 534 | } |
5260325f | 535 | |
57112b5a | 536 | /* |
7c49df64 | 537 | * We don't have the remote ip-address for connections |
538 | * using a proxy command | |
539 | */ | |
540 | if (options.proxy_command == NULL) { | |
541 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), | |
542 | NULL, 0, NI_NUMERICHOST) != 0) | |
543 | fatal("check_host_key: getnameinfo failed"); | |
544 | ip = xstrdup(ntop); | |
545 | } else { | |
546 | ip = xstrdup("<no hostip for proxy command>"); | |
547 | } | |
548 | /* | |
549 | * Turn off check_host_ip if the connection is to localhost, via proxy | |
550 | * command or if we don't have a hostname to compare with | |
57112b5a | 551 | */ |
7c49df64 | 552 | if (options.check_host_ip && |
553 | (local || strcmp(host, ip) == 0 || options.proxy_command != NULL)) | |
57112b5a | 554 | options.check_host_ip = 0; |
555 | ||
8abcdba4 | 556 | /* |
7c49df64 | 557 | * Allow the user to record the key under a different name. This is |
8abcdba4 | 558 | * useful for ssh tunneling over forwarded connections or if you run |
7c49df64 | 559 | * multiple sshd's on different ports on the same machine. |
8abcdba4 | 560 | */ |
561 | if (options.host_key_alias != NULL) { | |
562 | host = options.host_key_alias; | |
563 | debug("using hostkeyalias: %s", host); | |
564 | } | |
565 | ||
95f1eccc | 566 | /* |
567 | * Store the host key from the known host file in here so that we can | |
568 | * compare it with the key for the IP address. | |
569 | */ | |
4fe2af09 | 570 | file_key = key_new(host_key->type); |
5260325f | 571 | |
aa3378df | 572 | /* |
573 | * Check if the host key is present in the user\'s list of known | |
574 | * hosts or in the systemwide list. | |
575 | */ | |
1e3b8b07 | 576 | host_file = user_hostfile; |
f49bc4f7 | 577 | host_status = check_host_in_hostfile(host_file, host, host_key, |
184eed6a | 578 | file_key, &host_line); |
1e3b8b07 | 579 | if (host_status == HOST_NEW) { |
580 | host_file = system_hostfile; | |
f49bc4f7 | 581 | host_status = check_host_in_hostfile(host_file, host, host_key, |
582 | file_key, &host_line); | |
1e3b8b07 | 583 | } |
aa3378df | 584 | /* |
585 | * Also perform check for the ip address, skip the check if we are | |
586 | * localhost or the hostname was an ip address to begin with | |
587 | */ | |
7c49df64 | 588 | if (options.check_host_ip) { |
4fe2af09 | 589 | Key *ip_key = key_new(host_key->type); |
5260325f | 590 | |
1e3b8b07 | 591 | ip_file = user_hostfile; |
f49bc4f7 | 592 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, |
593 | ip_key, &ip_line); | |
1e3b8b07 | 594 | if (ip_status == HOST_NEW) { |
595 | ip_file = system_hostfile; | |
f49bc4f7 | 596 | ip_status = check_host_in_hostfile(ip_file, ip, |
597 | host_key, ip_key, &ip_line); | |
1e3b8b07 | 598 | } |
5260325f | 599 | if (host_status == HOST_CHANGED && |
4fe2af09 | 600 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) |
5260325f | 601 | host_ip_differ = 1; |
602 | ||
4fe2af09 | 603 | key_free(ip_key); |
5260325f | 604 | } else |
605 | ip_status = host_status; | |
606 | ||
4fe2af09 | 607 | key_free(file_key); |
5260325f | 608 | |
609 | switch (host_status) { | |
610 | case HOST_OK: | |
611 | /* The host is known and the key matches. */ | |
1d1ffb87 | 612 | debug("Host '%.200s' is known and matches the %s host key.", |
613 | host, type); | |
1e3b8b07 | 614 | debug("Found key in %s:%d", host_file, host_line); |
7c49df64 | 615 | if (options.check_host_ip && ip_status == HOST_NEW) { |
f49bc4f7 | 616 | if (readonly) |
bbe88b6d | 617 | logit("%s host key for IP address " |
f49bc4f7 | 618 | "'%.128s' not in list of known hosts.", |
7c49df64 | 619 | type, ip); |
f49bc4f7 | 620 | else if (!add_host_to_hostfile(user_hostfile, ip, |
184eed6a | 621 | host_key)) |
bbe88b6d | 622 | logit("Failed to add the %s host key for IP " |
f49bc4f7 | 623 | "address '%.128s' to the list of known " |
624 | "hosts (%.30s).", type, ip, user_hostfile); | |
625 | else | |
bbe88b6d | 626 | logit("Warning: Permanently added the %s host " |
f49bc4f7 | 627 | "key for IP address '%.128s' to the list " |
628 | "of known hosts.", type, ip); | |
5260325f | 629 | } |
630 | break; | |
631 | case HOST_NEW: | |
f49bc4f7 | 632 | if (readonly) |
633 | goto fail; | |
5260325f | 634 | /* The host is new. */ |
635 | if (options.strict_host_key_checking == 1) { | |
f49bc4f7 | 636 | /* |
637 | * User has requested strict host key checking. We | |
638 | * will not add the host key automatically. The only | |
639 | * alternative left is to abort. | |
640 | */ | |
641 | error("No %s host key is known for %.200s and you " | |
642 | "have requested strict checking.", type, host); | |
643 | goto fail; | |
5260325f | 644 | } else if (options.strict_host_key_checking == 2) { |
8a48a7ef | 645 | has_keys = show_other_keys(host, host_key); |
5260325f | 646 | /* The default */ |
22138a36 | 647 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
616a6b93 | 648 | snprintf(msg, sizeof(msg), |
f49bc4f7 | 649 | "The authenticity of host '%.200s (%s)' can't be " |
8a48a7ef | 650 | "established%s\n" |
1d1ffb87 | 651 | "%s key fingerprint is %s.\n" |
f49bc4f7 | 652 | "Are you sure you want to continue connecting " |
8a48a7ef | 653 | "(yes/no)? ", |
b77a87e5 | 654 | host, ip, |
655 | has_keys ? ",\nbut keys of different type are already " | |
656 | "known for this host." : ".", | |
657 | type, fp); | |
22138a36 | 658 | xfree(fp); |
616a6b93 | 659 | if (!confirm(msg)) |
f49bc4f7 | 660 | goto fail; |
5260325f | 661 | } |
7c49df64 | 662 | if (options.check_host_ip && ip_status == HOST_NEW) { |
5260325f | 663 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); |
664 | hostp = hostline; | |
665 | } else | |
666 | hostp = host; | |
667 | ||
f49bc4f7 | 668 | /* |
669 | * If not in strict mode, add the key automatically to the | |
670 | * local known_hosts file. | |
671 | */ | |
a306f2dd | 672 | if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) |
bbe88b6d | 673 | logit("Failed to add the host to the list of known " |
f49bc4f7 | 674 | "hosts (%.500s).", user_hostfile); |
5260325f | 675 | else |
bbe88b6d | 676 | logit("Warning: Permanently added '%.200s' (%s) to the " |
f49bc4f7 | 677 | "list of known hosts.", hostp, type); |
5260325f | 678 | break; |
679 | case HOST_CHANGED: | |
680 | if (options.check_host_ip && host_ip_differ) { | |
681 | char *msg; | |
682 | if (ip_status == HOST_NEW) | |
683 | msg = "is unknown"; | |
684 | else if (ip_status == HOST_OK) | |
685 | msg = "is unchanged"; | |
686 | else | |
687 | msg = "has a different value"; | |
688 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
689 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
690 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1d1ffb87 | 691 | error("The %s host key for %s has changed,", type, host); |
5260325f | 692 | error("and the key for the according IP address %s", ip); |
693 | error("%s. This could either mean that", msg); | |
694 | error("DNS SPOOFING is happening or the IP address for the host"); | |
1e3b8b07 | 695 | error("and its host key have changed at the same time."); |
7c49df64 | 696 | if (ip_status != HOST_NEW) |
1e3b8b07 | 697 | error("Offending key for IP in %s:%d", ip_file, ip_line); |
5260325f | 698 | } |
699 | /* The host key has changed. */ | |
22138a36 | 700 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
5260325f | 701 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
ae2f7af7 | 702 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); |
5260325f | 703 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
704 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
705 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
1d1ffb87 | 706 | error("It is also possible that the %s host key has just been changed.", type); |
8abcdba4 | 707 | error("The fingerprint for the %s key sent by the remote host is\n%s.", |
22138a36 | 708 | type, fp); |
5260325f | 709 | error("Please contact your system administrator."); |
710 | error("Add correct host key in %.100s to get rid of this message.", | |
8abcdba4 | 711 | user_hostfile); |
1e3b8b07 | 712 | error("Offending key in %s:%d", host_file, host_line); |
22138a36 | 713 | xfree(fp); |
5260325f | 714 | |
aa3378df | 715 | /* |
716 | * If strict host key checking is in use, the user will have | |
717 | * to edit the key manually and we can only abort. | |
718 | */ | |
f49bc4f7 | 719 | if (options.strict_host_key_checking) { |
720 | error("%s host key for %.200s has changed and you have " | |
721 | "requested strict checking.", type, host); | |
722 | goto fail; | |
723 | } | |
5260325f | 724 | |
aa3378df | 725 | /* |
726 | * If strict host key checking has not been requested, allow | |
727 | * the connection but without password authentication or | |
728 | * agent forwarding. | |
729 | */ | |
5260325f | 730 | if (options.password_authentication) { |
f49bc4f7 | 731 | error("Password authentication is disabled to avoid " |
732 | "man-in-the-middle attacks."); | |
5260325f | 733 | options.password_authentication = 0; |
734 | } | |
735 | if (options.forward_agent) { | |
f49bc4f7 | 736 | error("Agent forwarding is disabled to avoid " |
737 | "man-in-the-middle attacks."); | |
5260325f | 738 | options.forward_agent = 0; |
739 | } | |
0b6fbf03 | 740 | if (options.forward_x11) { |
f49bc4f7 | 741 | error("X11 forwarding is disabled to avoid " |
742 | "man-in-the-middle attacks."); | |
0b6fbf03 | 743 | options.forward_x11 = 0; |
744 | } | |
f49bc4f7 | 745 | if (options.num_local_forwards > 0 || |
746 | options.num_remote_forwards > 0) { | |
747 | error("Port forwarding is disabled to avoid " | |
748 | "man-in-the-middle attacks."); | |
749 | options.num_local_forwards = | |
184eed6a | 750 | options.num_remote_forwards = 0; |
0b6fbf03 | 751 | } |
aa3378df | 752 | /* |
753 | * XXX Should permit the user to change to use the new id. | |
754 | * This could be done by converting the host key to an | |
755 | * identifying sentence, tell that the host identifies itself | |
756 | * by that sentence, and ask the user if he/she whishes to | |
757 | * accept the authentication. | |
758 | */ | |
5260325f | 759 | break; |
8a48a7ef | 760 | case HOST_FOUND: |
761 | fatal("internal error"); | |
762 | break; | |
5260325f | 763 | } |
0b6fbf03 | 764 | |
7c49df64 | 765 | if (options.check_host_ip && host_status != HOST_CHANGED && |
766 | ip_status == HOST_CHANGED) { | |
616a6b93 | 767 | snprintf(msg, sizeof(msg), |
768 | "Warning: the %s host key for '%.200s' " | |
769 | "differs from the key for the IP address '%.128s'" | |
770 | "\nOffending key for IP in %s:%d", | |
771 | type, host, ip, ip_file, ip_line); | |
772 | if (host_status == HOST_OK) { | |
773 | len = strlen(msg); | |
774 | snprintf(msg + len, sizeof(msg) - len, | |
775 | "\nMatching host key in %s:%d", | |
7203d6bb | 776 | host_file, host_line); |
616a6b93 | 777 | } |
7c49df64 | 778 | if (options.strict_host_key_checking == 1) { |
bbe88b6d | 779 | logit(msg); |
f49bc4f7 | 780 | error("Exiting, you have requested strict checking."); |
781 | goto fail; | |
7c49df64 | 782 | } else if (options.strict_host_key_checking == 2) { |
616a6b93 | 783 | strlcat(msg, "\nAre you sure you want " |
784 | "to continue connecting (yes/no)? ", sizeof(msg)); | |
785 | if (!confirm(msg)) | |
f49bc4f7 | 786 | goto fail; |
616a6b93 | 787 | } else { |
bbe88b6d | 788 | logit(msg); |
7c49df64 | 789 | } |
790 | } | |
791 | ||
0b6fbf03 | 792 | xfree(ip); |
f49bc4f7 | 793 | return 0; |
794 | ||
795 | fail: | |
796 | xfree(ip); | |
797 | return -1; | |
798 | } | |
799 | ||
800 | int | |
801 | verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) | |
802 | { | |
803 | struct stat st; | |
804 | ||
805 | /* return ok if the key can be found in an old keyfile */ | |
806 | if (stat(options.system_hostfile2, &st) == 0 || | |
807 | stat(options.user_hostfile2, &st) == 0) { | |
808 | if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1, | |
809 | options.user_hostfile2, options.system_hostfile2) == 0) | |
810 | return 0; | |
811 | } | |
812 | return check_host_key(host, hostaddr, host_key, /*readonly*/ 0, | |
813 | options.user_hostfile, options.system_hostfile); | |
95f1eccc | 814 | } |
815 | ||
8ce64345 | 816 | /* |
a306f2dd | 817 | * Starts a dialog with the server, and authenticates the current user on the |
818 | * server. This does not need any extra privileges. The basic connection | |
819 | * to the server must already have been established before this is called. | |
820 | * If login fails, this function prints an error and never returns. | |
821 | * This function does not require super-user privileges. | |
8ce64345 | 822 | */ |
823 | void | |
39c00dc2 | 824 | ssh_login(Sensitive *sensitive, const char *orighost, |
63bd8c36 | 825 | struct sockaddr *hostaddr, struct passwd *pw) |
8ce64345 | 826 | { |
a306f2dd | 827 | char *host, *cp; |
8ce64345 | 828 | char *server_user, *local_user; |
8ce64345 | 829 | |
8ce64345 | 830 | local_user = xstrdup(pw->pw_name); |
831 | server_user = options.user ? options.user : local_user; | |
832 | ||
7b2ea3a1 | 833 | /* Convert the user-supplied hostname into all lowercase. */ |
834 | host = xstrdup(orighost); | |
835 | for (cp = host; *cp; cp++) | |
836 | if (isupper(*cp)) | |
837 | *cp = tolower(*cp); | |
838 | ||
839 | /* Exchange protocol version identification strings with the server. */ | |
840 | ssh_exchange_identification(); | |
841 | ||
842 | /* Put the connection into non-blocking mode. */ | |
843 | packet_set_nonblocking(); | |
844 | ||
7b2ea3a1 | 845 | /* key exchange */ |
7b2ea3a1 | 846 | /* authenticate user */ |
8ce64345 | 847 | if (compat20) { |
848 | ssh_kex2(host, hostaddr); | |
39c00dc2 | 849 | ssh_userauth2(local_user, server_user, host, sensitive); |
8ce64345 | 850 | } else { |
8ce64345 | 851 | ssh_kex(host, hostaddr); |
39c00dc2 | 852 | ssh_userauth1(local_user, server_user, host, sensitive); |
8ce64345 | 853 | } |
7b2ea3a1 | 854 | } |
0ae4fe1d | 855 | |
856 | void | |
857 | ssh_put_password(char *password) | |
858 | { | |
859 | int size; | |
860 | char *padded; | |
861 | ||
99c415db | 862 | if (datafellows & SSH_BUG_PASSWORDPAD) { |
449c5ba5 | 863 | packet_put_cstring(password); |
99c415db | 864 | return; |
865 | } | |
0ae4fe1d | 866 | size = roundup(strlen(password) + 1, 32); |
867 | padded = xmalloc(size); | |
868 | memset(padded, 0, size); | |
869 | strlcpy(padded, password, size); | |
870 | packet_put_string(padded, size); | |
871 | memset(padded, 0, size); | |
872 | xfree(padded); | |
873 | } | |
8a48a7ef | 874 | |
875 | static int | |
876 | show_key_from_file(const char *file, const char *host, int keytype) | |
877 | { | |
878 | Key *found; | |
879 | char *fp; | |
880 | int line, ret; | |
881 | ||
882 | found = key_new(keytype); | |
883 | if ((ret = lookup_key_in_hostfile_by_type(file, host, | |
884 | keytype, found, &line))) { | |
885 | fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX); | |
bbe88b6d | 886 | logit("WARNING: %s key found for host %s\n" |
567a05bf | 887 | "in %s:%d\n" |
8a48a7ef | 888 | "%s key fingerprint %s.", |
889 | key_type(found), host, file, line, | |
890 | key_type(found), fp); | |
891 | xfree(fp); | |
892 | } | |
893 | key_free(found); | |
894 | return (ret); | |
895 | } | |
896 | ||
897 | /* print all known host keys for a given host, but skip keys of given type */ | |
898 | static int | |
899 | show_other_keys(const char *host, Key *key) | |
900 | { | |
901 | int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1}; | |
902 | int i, found = 0; | |
903 | ||
904 | for (i = 0; type[i] != -1; i++) { | |
905 | if (type[i] == key->type) | |
906 | continue; | |
907 | if (type[i] != KEY_RSA1 && | |
908 | show_key_from_file(options.user_hostfile2, host, type[i])) { | |
909 | found = 1; | |
910 | continue; | |
911 | } | |
912 | if (type[i] != KEY_RSA1 && | |
913 | show_key_from_file(options.system_hostfile2, host, type[i])) { | |
914 | found = 1; | |
915 | continue; | |
916 | } | |
917 | if (show_key_from_file(options.user_hostfile, host, type[i])) { | |
918 | found = 1; | |
919 | continue; | |
920 | } | |
921 | if (show_key_from_file(options.system_hostfile, host, type[i])) { | |
922 | found = 1; | |
923 | continue; | |
924 | } | |
925 | debug2("no key of type %d for host %s", type[i], host); | |
926 | } | |
927 | return (found); | |
928 | } |