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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" | |
d6133f43 | 16 | RCSID("$OpenBSD: sshconnect.c,v 1.126 2002/06/23 03:30:17 deraadt 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; | |
57112b5a | 44 | |
a704dd54 | 45 | #ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */ |
46 | #define INET6_ADDRSTRLEN 46 | |
47 | #endif | |
48 | ||
ce773142 | 49 | static const char * |
01ca0dfe | 50 | sockaddr_ntop(struct sockaddr *sa, socklen_t salen) |
ce773142 | 51 | { |
35ad6a0a | 52 | static char addrbuf[NI_MAXHOST]; |
ce773142 | 53 | |
01ca0dfe | 54 | if (getnameinfo(sa, salen, addrbuf, sizeof(addrbuf), NULL, 0, |
35ad6a0a | 55 | NI_NUMERICHOST) != 0) |
b0ff7493 | 56 | fatal("sockaddr_ntop: getnameinfo NI_NUMERICHOST failed"); |
ce773142 | 57 | return addrbuf; |
58 | } | |
59 | ||
5260325f | 60 | /* |
61 | * Connect to the given ssh server using a proxy command. | |
62 | */ | |
396c147e | 63 | static int |
3fb156df | 64 | ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) |
8efc0c15 | 65 | { |
5260325f | 66 | Buffer command; |
67 | const char *cp; | |
68 | char *command_string; | |
69 | int pin[2], pout[2]; | |
9da5c3c9 | 70 | pid_t pid; |
48e671d5 | 71 | char strport[NI_MAXSERV]; |
5260325f | 72 | |
73 | /* Convert the port number into a string. */ | |
48e671d5 | 74 | snprintf(strport, sizeof strport, "%hu", port); |
5260325f | 75 | |
76 | /* Build the final command string in the buffer by making the | |
77 | appropriate substitutions to the given proxy command. */ | |
78 | buffer_init(&command); | |
79 | for (cp = proxy_command; *cp; cp++) { | |
80 | if (cp[0] == '%' && cp[1] == '%') { | |
81 | buffer_append(&command, "%", 1); | |
82 | cp++; | |
83 | continue; | |
84 | } | |
85 | if (cp[0] == '%' && cp[1] == 'h') { | |
86 | buffer_append(&command, host, strlen(host)); | |
87 | cp++; | |
88 | continue; | |
89 | } | |
90 | if (cp[0] == '%' && cp[1] == 'p') { | |
48e671d5 | 91 | buffer_append(&command, strport, strlen(strport)); |
5260325f | 92 | cp++; |
93 | continue; | |
94 | } | |
95 | buffer_append(&command, cp, 1); | |
8efc0c15 | 96 | } |
5260325f | 97 | buffer_append(&command, "\0", 1); |
98 | ||
99 | /* Get the final command string. */ | |
100 | command_string = buffer_ptr(&command); | |
101 | ||
102 | /* Create pipes for communicating with the proxy. */ | |
103 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
104 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
184eed6a | 105 | strerror(errno)); |
5260325f | 106 | |
107 | debug("Executing proxy command: %.500s", command_string); | |
108 | ||
109 | /* Fork and execute the proxy command. */ | |
110 | if ((pid = fork()) == 0) { | |
111 | char *argv[10]; | |
112 | ||
113 | /* Child. Permanently give up superuser privileges. */ | |
3fb156df | 114 | seteuid(original_real_uid); |
115 | setuid(original_real_uid); | |
5260325f | 116 | |
117 | /* Redirect stdin and stdout. */ | |
118 | close(pin[1]); | |
119 | if (pin[0] != 0) { | |
120 | if (dup2(pin[0], 0) < 0) | |
121 | perror("dup2 stdin"); | |
122 | close(pin[0]); | |
123 | } | |
124 | close(pout[0]); | |
125 | if (dup2(pout[1], 1) < 0) | |
126 | perror("dup2 stdout"); | |
127 | /* Cannot be 1 because pin allocated two descriptors. */ | |
128 | close(pout[1]); | |
129 | ||
130 | /* Stderr is left as it is so that error messages get | |
131 | printed on the user's terminal. */ | |
30228d7c | 132 | argv[0] = _PATH_BSHELL; |
5260325f | 133 | argv[1] = "-c"; |
134 | argv[2] = command_string; | |
135 | argv[3] = NULL; | |
136 | ||
137 | /* Execute the proxy command. Note that we gave up any | |
138 | extra privileges above. */ | |
328654d8 | 139 | execv(argv[0], argv); |
140 | perror(argv[0]); | |
5260325f | 141 | exit(1); |
8efc0c15 | 142 | } |
5260325f | 143 | /* Parent. */ |
144 | if (pid < 0) | |
145 | fatal("fork failed: %.100s", strerror(errno)); | |
146 | ||
147 | /* Close child side of the descriptors. */ | |
148 | close(pin[0]); | |
149 | close(pout[1]); | |
150 | ||
151 | /* Free the command name. */ | |
152 | buffer_free(&command); | |
153 | ||
154 | /* Set the connection file descriptors. */ | |
155 | packet_set_connection(pout[0], pin[1]); | |
8efc0c15 | 156 | |
ce773142 | 157 | /* Indicate OK return */ |
158 | return 0; | |
5260325f | 159 | } |
8efc0c15 | 160 | |
5260325f | 161 | /* |
162 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
163 | */ | |
396c147e | 164 | static int |
3fb156df | 165 | ssh_create_socket(int privileged, int family) |
8efc0c15 | 166 | { |
3435f5a6 | 167 | int sock, gaierr; |
168 | struct addrinfo hints, *res; | |
5260325f | 169 | |
aa3378df | 170 | /* |
171 | * If we are running as root and want to connect to a privileged | |
172 | * port, bind our own socket to a privileged port. | |
173 | */ | |
5260325f | 174 | if (privileged) { |
175 | int p = IPPORT_RESERVED - 1; | |
3fb156df | 176 | PRIV_START; |
48e671d5 | 177 | sock = rresvport_af(&p, family); |
3fb156df | 178 | PRIV_END; |
5260325f | 179 | if (sock < 0) |
c8d54615 | 180 | error("rresvport: af=%d %.100s", family, strerror(errno)); |
181 | else | |
182 | debug("Allocated local port %d.", p); | |
3435f5a6 | 183 | return sock; |
184 | } | |
3435f5a6 | 185 | sock = socket(family, SOCK_STREAM, 0); |
186 | if (sock < 0) | |
187 | error("socket: %.100s", strerror(errno)); | |
3435f5a6 | 188 | |
189 | /* Bind the socket to an alternative local IP address */ | |
190 | if (options.bind_address == NULL) | |
191 | return sock; | |
192 | ||
193 | memset(&hints, 0, sizeof(hints)); | |
32af6a3f | 194 | hints.ai_family = family; |
3435f5a6 | 195 | hints.ai_socktype = SOCK_STREAM; |
196 | hints.ai_flags = AI_PASSIVE; | |
197 | gaierr = getaddrinfo(options.bind_address, "0", &hints, &res); | |
198 | if (gaierr) { | |
199 | error("getaddrinfo: %s: %s", options.bind_address, | |
200 | gai_strerror(gaierr)); | |
201 | close(sock); | |
202 | return -1; | |
203 | } | |
204 | if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { | |
205 | error("bind: %s: %s", options.bind_address, strerror(errno)); | |
206 | close(sock); | |
207 | freeaddrinfo(res); | |
208 | return -1; | |
5260325f | 209 | } |
3435f5a6 | 210 | freeaddrinfo(res); |
5260325f | 211 | return sock; |
8efc0c15 | 212 | } |
213 | ||
5260325f | 214 | /* |
48e671d5 | 215 | * Opens a TCP/IP connection to the remote server on the given host. |
216 | * The address of the remote host will be returned in hostaddr. | |
3fb156df | 217 | * If port is 0, the default port will be used. If needpriv is true, |
5260325f | 218 | * a privileged port will be allocated to make the connection. |
3fb156df | 219 | * This requires super-user privileges if needpriv is true. |
5260325f | 220 | * Connection_attempts specifies the maximum number of tries (one per |
221 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
222 | * and %p substituted for host and port, respectively) to use to contact | |
223 | * the daemon. | |
ce773142 | 224 | * Return values: |
225 | * 0 for OK | |
226 | * ECONNREFUSED if we got a "Connection Refused" by the peer on any address | |
227 | * ECONNABORTED if we failed without a "Connection refused" | |
228 | * Suitable error messages for the connection failure will already have been | |
229 | * printed. | |
5260325f | 230 | */ |
231 | int | |
48e671d5 | 232 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, |
dab89049 | 233 | u_short port, int family, int connection_attempts, |
3fb156df | 234 | int needpriv, const char *proxy_command) |
8efc0c15 | 235 | { |
b5c334cc | 236 | int gaierr; |
237 | int on = 1; | |
48e671d5 | 238 | int sock = -1, attempt; |
48e671d5 | 239 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; |
b5c334cc | 240 | struct addrinfo hints, *ai, *aitop; |
5260325f | 241 | struct linger linger; |
b5c334cc | 242 | struct servent *sp; |
ce773142 | 243 | /* |
244 | * Did we get only other errors than "Connection refused" (which | |
245 | * should block fallback to rsh and similar), or did we get at least | |
246 | * one "Connection refused"? | |
247 | */ | |
248 | int full_failure = 1; | |
5260325f | 249 | |
3fb156df | 250 | debug("ssh_connect: needpriv %d", needpriv); |
5260325f | 251 | |
252 | /* Get default port if port has not been set. */ | |
253 | if (port == 0) { | |
254 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
255 | if (sp) | |
256 | port = ntohs(sp->s_port); | |
257 | else | |
258 | port = SSH_DEFAULT_PORT; | |
8efc0c15 | 259 | } |
5260325f | 260 | /* If a proxy command is given, connect using it. */ |
261 | if (proxy_command != NULL) | |
3fb156df | 262 | return ssh_proxy_connect(host, port, proxy_command); |
5260325f | 263 | |
264 | /* No proxy command. */ | |
265 | ||
48e671d5 | 266 | memset(&hints, 0, sizeof(hints)); |
dab89049 | 267 | hints.ai_family = family; |
48e671d5 | 268 | hints.ai_socktype = SOCK_STREAM; |
d6133f43 | 269 | snprintf(strport, sizeof strport, "%u", port); |
48e671d5 | 270 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) |
271 | fatal("%s: %.100s: %s", __progname, host, | |
272 | gai_strerror(gaierr)); | |
5260325f | 273 | |
95f1eccc | 274 | /* |
275 | * Try to connect several times. On some machines, the first time | |
276 | * will sometimes fail. In general socket code appears to behave | |
277 | * quite magically on many machines. | |
ce773142 | 278 | */ |
279 | for (attempt = 0; ;) { | |
5260325f | 280 | if (attempt > 0) |
281 | debug("Trying again..."); | |
282 | ||
48e671d5 | 283 | /* Loop through addresses for this host, and try each one in |
6ae2364d | 284 | sequence until the connection succeeds. */ |
48e671d5 | 285 | for (ai = aitop; ai; ai = ai->ai_next) { |
286 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
287 | continue; | |
288 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
289 | ntop, sizeof(ntop), strport, sizeof(strport), | |
290 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
291 | error("ssh_connect: getnameinfo failed"); | |
292 | continue; | |
293 | } | |
294 | debug("Connecting to %.200s [%.100s] port %s.", | |
295 | host, ntop, strport); | |
296 | ||
297 | /* Create a socket for connecting. */ | |
3fb156df | 298 | sock = ssh_create_socket(needpriv, ai->ai_family); |
48e671d5 | 299 | if (sock < 0) |
ce773142 | 300 | /* Any error is already output */ |
48e671d5 | 301 | continue; |
302 | ||
48e671d5 | 303 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { |
304 | /* Successful connection. */ | |
cd332296 | 305 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); |
5260325f | 306 | break; |
48e671d5 | 307 | } else { |
ce773142 | 308 | if (errno == ECONNREFUSED) |
309 | full_failure = 0; | |
310 | log("ssh: connect to address %s port %s: %s", | |
01ca0dfe | 311 | sockaddr_ntop(ai->ai_addr, ai->ai_addrlen), |
312 | strport, strerror(errno)); | |
aa3378df | 313 | /* |
314 | * Close the failed socket; there appear to | |
315 | * be some problems when reusing a socket for | |
316 | * which connect() has already returned an | |
317 | * error. | |
318 | */ | |
5260325f | 319 | close(sock); |
320 | } | |
8efc0c15 | 321 | } |
48e671d5 | 322 | if (ai) |
323 | break; /* Successful connection. */ | |
8efc0c15 | 324 | |
ce773142 | 325 | attempt++; |
326 | if (attempt >= connection_attempts) | |
327 | break; | |
5260325f | 328 | /* Sleep a moment before retrying. */ |
329 | sleep(1); | |
330 | } | |
48e671d5 | 331 | |
332 | freeaddrinfo(aitop); | |
333 | ||
5260325f | 334 | /* Return failure if we didn't get a successful connection. */ |
335 | if (attempt >= connection_attempts) | |
ce773142 | 336 | return full_failure ? ECONNABORTED : ECONNREFUSED; |
8efc0c15 | 337 | |
5260325f | 338 | debug("Connection established."); |
8efc0c15 | 339 | |
aa3378df | 340 | /* |
341 | * Set socket options. We would like the socket to disappear as soon | |
342 | * as it has been closed for whatever reason. | |
343 | */ | |
344 | /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 345 | linger.l_onoff = 1; |
346 | linger.l_linger = 5; | |
b5c334cc | 347 | setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger)); |
348 | ||
349 | /* Set keepalives if requested. */ | |
350 | if (options.keepalives && | |
351 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, | |
352 | sizeof(on)) < 0) | |
353 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
8efc0c15 | 354 | |
5260325f | 355 | /* Set the connection. */ |
356 | packet_set_connection(sock, sock); | |
8efc0c15 | 357 | |
ce773142 | 358 | return 0; |
8efc0c15 | 359 | } |
360 | ||
5260325f | 361 | /* |
362 | * Waits for the server identification string, and sends our own | |
363 | * identification string. | |
364 | */ | |
396c147e | 365 | static void |
5ca51e19 | 366 | ssh_exchange_identification(void) |
8efc0c15 | 367 | { |
5260325f | 368 | char buf[256], remote_version[256]; /* must be same size! */ |
a8be9f80 | 369 | int remote_major, remote_minor, i, mismatch; |
5260325f | 370 | int connection_in = packet_get_connection_in(); |
371 | int connection_out = packet_get_connection_out(); | |
2b87da3b | 372 | int minor1 = PROTOCOL_MINOR_1; |
5260325f | 373 | |
374 | /* Read other side\'s version identification. */ | |
38c295d6 | 375 | for (;;) { |
376 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
377 | int len = atomicio(read, connection_in, &buf[i], 1); | |
378 | if (len < 0) | |
379 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); | |
380 | if (len != 1) | |
381 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
382 | if (buf[i] == '\r') { | |
383 | buf[i] = '\n'; | |
384 | buf[i + 1] = 0; | |
385 | continue; /**XXX wait for \n */ | |
386 | } | |
387 | if (buf[i] == '\n') { | |
388 | buf[i + 1] = 0; | |
389 | break; | |
390 | } | |
5260325f | 391 | } |
38c295d6 | 392 | buf[sizeof(buf) - 1] = 0; |
393 | if (strncmp(buf, "SSH-", 4) == 0) | |
5260325f | 394 | break; |
38c295d6 | 395 | debug("ssh_exchange_identification: %s", buf); |
8efc0c15 | 396 | } |
8ce64345 | 397 | server_version_string = xstrdup(buf); |
5260325f | 398 | |
aa3378df | 399 | /* |
400 | * Check that the versions match. In future this might accept | |
401 | * several versions and set appropriate flags to handle them. | |
402 | */ | |
8ce64345 | 403 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", |
404 | &remote_major, &remote_minor, remote_version) != 3) | |
5260325f | 405 | fatal("Bad remote protocol version identification: '%.100s'", buf); |
406 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
184eed6a | 407 | remote_major, remote_minor, remote_version); |
5260325f | 408 | |
8ce64345 | 409 | compat_datafellows(remote_version); |
a8be9f80 | 410 | mismatch = 0; |
411 | ||
6aacefa7 | 412 | switch (remote_major) { |
a8be9f80 | 413 | case 1: |
414 | if (remote_minor == 99 && | |
415 | (options.protocol & SSH_PROTO_2) && | |
416 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
417 | enable_compat20(); | |
418 | break; | |
5260325f | 419 | } |
a8be9f80 | 420 | if (!(options.protocol & SSH_PROTO_1)) { |
421 | mismatch = 1; | |
422 | break; | |
423 | } | |
424 | if (remote_minor < 3) { | |
425 | fatal("Remote machine has too old SSH software version."); | |
fa08c86b | 426 | } else if (remote_minor == 3 || remote_minor == 4) { |
a8be9f80 | 427 | /* We speak 1.3, too. */ |
428 | enable_compat13(); | |
fa08c86b | 429 | minor1 = 3; |
a8be9f80 | 430 | if (options.forward_agent) { |
431 | log("Agent forwarding disabled for protocol 1.3"); | |
432 | options.forward_agent = 0; | |
433 | } | |
434 | } | |
435 | break; | |
436 | case 2: | |
437 | if (options.protocol & SSH_PROTO_2) { | |
438 | enable_compat20(); | |
439 | break; | |
440 | } | |
441 | /* FALLTHROUGH */ | |
6ae2364d | 442 | default: |
a8be9f80 | 443 | mismatch = 1; |
444 | break; | |
8efc0c15 | 445 | } |
a8be9f80 | 446 | if (mismatch) |
5260325f | 447 | fatal("Protocol major versions differ: %d vs. %d", |
a8be9f80 | 448 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
449 | remote_major); | |
5260325f | 450 | /* Send our own protocol version identification. */ |
451 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
a8be9f80 | 452 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
fa08c86b | 453 | compat20 ? PROTOCOL_MINOR_2 : minor1, |
8ce64345 | 454 | SSH_VERSION); |
a408af76 | 455 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) |
5260325f | 456 | fatal("write: %.100s", strerror(errno)); |
8ce64345 | 457 | client_version_string = xstrdup(buf); |
458 | chop(client_version_string); | |
459 | chop(server_version_string); | |
460 | debug("Local version string %.100s", client_version_string); | |
8efc0c15 | 461 | } |
462 | ||
f21032a6 | 463 | /* defaults to 'no' */ |
396c147e | 464 | static int |
a2c92c4a | 465 | confirm(const char *prompt) |
8efc0c15 | 466 | { |
616a6b93 | 467 | const char *msg, *again = "Please type 'yes' or 'no': "; |
468 | char *p; | |
469 | int ret = -1; | |
5260325f | 470 | |
f21032a6 | 471 | if (options.batch_mode) |
472 | return 0; | |
616a6b93 | 473 | for (msg = prompt;;msg = again) { |
474 | p = read_passphrase(msg, RP_ECHO); | |
475 | if (p == NULL || | |
476 | (p[0] == '\0') || (p[0] == '\n') || | |
477 | strncasecmp(p, "no", 2) == 0) | |
478 | ret = 0; | |
479 | if (strncasecmp(p, "yes", 3) == 0) | |
480 | ret = 1; | |
481 | if (p) | |
482 | xfree(p); | |
483 | if (ret != -1) | |
484 | return ret; | |
8efc0c15 | 485 | } |
8efc0c15 | 486 | } |
487 | ||
5260325f | 488 | /* |
f49bc4f7 | 489 | * check whether the supplied host key is valid, return -1 if the key |
490 | * is not valid. the user_hostfile will not be updated if 'readonly' is true. | |
5260325f | 491 | */ |
396c147e | 492 | static int |
a306f2dd | 493 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, |
f49bc4f7 | 494 | int readonly, const char *user_hostfile, const char *system_hostfile) |
8efc0c15 | 495 | { |
4fe2af09 | 496 | Key *file_key; |
1d1ffb87 | 497 | char *type = key_type(host_key); |
95f1eccc | 498 | char *ip = NULL; |
22138a36 | 499 | char hostline[1000], *hostp, *fp; |
5260325f | 500 | HostStatus host_status; |
501 | HostStatus ip_status; | |
48e671d5 | 502 | int local = 0, host_ip_differ = 0; |
20af321f | 503 | int salen; |
48e671d5 | 504 | char ntop[NI_MAXHOST]; |
616a6b93 | 505 | char msg[1024]; |
506 | int len, host_line, ip_line; | |
1e3b8b07 | 507 | const char *host_file = NULL, *ip_file = NULL; |
48e671d5 | 508 | |
509 | /* | |
510 | * Force accepting of the host key for loopback/localhost. The | |
511 | * problem is that if the home directory is NFS-mounted to multiple | |
512 | * machines, localhost will refer to a different machine in each of | |
513 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
514 | * essentially disables host authentication for localhost; however, | |
515 | * this is probably not a real problem. | |
516 | */ | |
a306f2dd | 517 | /** hostaddr == 0! */ |
48e671d5 | 518 | switch (hostaddr->sa_family) { |
519 | case AF_INET: | |
f49bc4f7 | 520 | local = (ntohl(((struct sockaddr_in *)hostaddr)-> |
20a11d35 | 521 | sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; |
20af321f | 522 | salen = sizeof(struct sockaddr_in); |
48e671d5 | 523 | break; |
524 | case AF_INET6: | |
f49bc4f7 | 525 | local = IN6_IS_ADDR_LOOPBACK( |
526 | &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
20af321f | 527 | salen = sizeof(struct sockaddr_in6); |
48e671d5 | 528 | break; |
529 | default: | |
530 | local = 0; | |
20af321f | 531 | salen = sizeof(struct sockaddr_storage); |
48e671d5 | 532 | break; |
533 | } | |
8bbc048a | 534 | if (options.no_host_authentication_for_localhost == 1 && local && |
535 | options.host_key_alias == NULL) { | |
7c49df64 | 536 | debug("Forcing accepting of host key for " |
537 | "loopback/localhost."); | |
f49bc4f7 | 538 | return 0; |
48e671d5 | 539 | } |
5260325f | 540 | |
57112b5a | 541 | /* |
7c49df64 | 542 | * We don't have the remote ip-address for connections |
543 | * using a proxy command | |
544 | */ | |
545 | if (options.proxy_command == NULL) { | |
546 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), | |
547 | NULL, 0, NI_NUMERICHOST) != 0) | |
548 | fatal("check_host_key: getnameinfo failed"); | |
549 | ip = xstrdup(ntop); | |
550 | } else { | |
551 | ip = xstrdup("<no hostip for proxy command>"); | |
552 | } | |
553 | /* | |
554 | * Turn off check_host_ip if the connection is to localhost, via proxy | |
555 | * command or if we don't have a hostname to compare with | |
57112b5a | 556 | */ |
7c49df64 | 557 | if (options.check_host_ip && |
558 | (local || strcmp(host, ip) == 0 || options.proxy_command != NULL)) | |
57112b5a | 559 | options.check_host_ip = 0; |
560 | ||
8abcdba4 | 561 | /* |
7c49df64 | 562 | * Allow the user to record the key under a different name. This is |
8abcdba4 | 563 | * useful for ssh tunneling over forwarded connections or if you run |
7c49df64 | 564 | * multiple sshd's on different ports on the same machine. |
8abcdba4 | 565 | */ |
566 | if (options.host_key_alias != NULL) { | |
567 | host = options.host_key_alias; | |
568 | debug("using hostkeyalias: %s", host); | |
569 | } | |
570 | ||
95f1eccc | 571 | /* |
572 | * Store the host key from the known host file in here so that we can | |
573 | * compare it with the key for the IP address. | |
574 | */ | |
4fe2af09 | 575 | file_key = key_new(host_key->type); |
5260325f | 576 | |
aa3378df | 577 | /* |
578 | * Check if the host key is present in the user\'s list of known | |
579 | * hosts or in the systemwide list. | |
580 | */ | |
1e3b8b07 | 581 | host_file = user_hostfile; |
f49bc4f7 | 582 | host_status = check_host_in_hostfile(host_file, host, host_key, |
184eed6a | 583 | file_key, &host_line); |
1e3b8b07 | 584 | if (host_status == HOST_NEW) { |
585 | host_file = system_hostfile; | |
f49bc4f7 | 586 | host_status = check_host_in_hostfile(host_file, host, host_key, |
587 | file_key, &host_line); | |
1e3b8b07 | 588 | } |
aa3378df | 589 | /* |
590 | * Also perform check for the ip address, skip the check if we are | |
591 | * localhost or the hostname was an ip address to begin with | |
592 | */ | |
7c49df64 | 593 | if (options.check_host_ip) { |
4fe2af09 | 594 | Key *ip_key = key_new(host_key->type); |
5260325f | 595 | |
1e3b8b07 | 596 | ip_file = user_hostfile; |
f49bc4f7 | 597 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, |
598 | ip_key, &ip_line); | |
1e3b8b07 | 599 | if (ip_status == HOST_NEW) { |
600 | ip_file = system_hostfile; | |
f49bc4f7 | 601 | ip_status = check_host_in_hostfile(ip_file, ip, |
602 | host_key, ip_key, &ip_line); | |
1e3b8b07 | 603 | } |
5260325f | 604 | if (host_status == HOST_CHANGED && |
4fe2af09 | 605 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) |
5260325f | 606 | host_ip_differ = 1; |
607 | ||
4fe2af09 | 608 | key_free(ip_key); |
5260325f | 609 | } else |
610 | ip_status = host_status; | |
611 | ||
4fe2af09 | 612 | key_free(file_key); |
5260325f | 613 | |
614 | switch (host_status) { | |
615 | case HOST_OK: | |
616 | /* The host is known and the key matches. */ | |
1d1ffb87 | 617 | debug("Host '%.200s' is known and matches the %s host key.", |
618 | host, type); | |
1e3b8b07 | 619 | debug("Found key in %s:%d", host_file, host_line); |
7c49df64 | 620 | if (options.check_host_ip && ip_status == HOST_NEW) { |
f49bc4f7 | 621 | if (readonly) |
622 | log("%s host key for IP address " | |
623 | "'%.128s' not in list of known hosts.", | |
7c49df64 | 624 | type, ip); |
f49bc4f7 | 625 | else if (!add_host_to_hostfile(user_hostfile, ip, |
184eed6a | 626 | host_key)) |
f49bc4f7 | 627 | log("Failed to add the %s host key for IP " |
628 | "address '%.128s' to the list of known " | |
629 | "hosts (%.30s).", type, ip, user_hostfile); | |
630 | else | |
631 | log("Warning: Permanently added the %s host " | |
632 | "key for IP address '%.128s' to the list " | |
633 | "of known hosts.", type, ip); | |
5260325f | 634 | } |
635 | break; | |
636 | case HOST_NEW: | |
f49bc4f7 | 637 | if (readonly) |
638 | goto fail; | |
5260325f | 639 | /* The host is new. */ |
640 | if (options.strict_host_key_checking == 1) { | |
f49bc4f7 | 641 | /* |
642 | * User has requested strict host key checking. We | |
643 | * will not add the host key automatically. The only | |
644 | * alternative left is to abort. | |
645 | */ | |
646 | error("No %s host key is known for %.200s and you " | |
647 | "have requested strict checking.", type, host); | |
648 | goto fail; | |
5260325f | 649 | } else if (options.strict_host_key_checking == 2) { |
650 | /* The default */ | |
22138a36 | 651 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
616a6b93 | 652 | snprintf(msg, sizeof(msg), |
f49bc4f7 | 653 | "The authenticity of host '%.200s (%s)' can't be " |
654 | "established.\n" | |
1d1ffb87 | 655 | "%s key fingerprint is %s.\n" |
f49bc4f7 | 656 | "Are you sure you want to continue connecting " |
657 | "(yes/no)? ", host, ip, 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)) |
f49bc4f7 | 673 | log("Failed to add the host to the list of known " |
674 | "hosts (%.500s).", user_hostfile); | |
5260325f | 675 | else |
f49bc4f7 | 676 | log("Warning: Permanently added '%.200s' (%s) to the " |
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; |
760 | } | |
0b6fbf03 | 761 | |
7c49df64 | 762 | if (options.check_host_ip && host_status != HOST_CHANGED && |
763 | ip_status == HOST_CHANGED) { | |
616a6b93 | 764 | snprintf(msg, sizeof(msg), |
765 | "Warning: the %s host key for '%.200s' " | |
766 | "differs from the key for the IP address '%.128s'" | |
767 | "\nOffending key for IP in %s:%d", | |
768 | type, host, ip, ip_file, ip_line); | |
769 | if (host_status == HOST_OK) { | |
770 | len = strlen(msg); | |
771 | snprintf(msg + len, sizeof(msg) - len, | |
772 | "\nMatching host key in %s:%d", | |
7203d6bb | 773 | host_file, host_line); |
616a6b93 | 774 | } |
7c49df64 | 775 | if (options.strict_host_key_checking == 1) { |
616a6b93 | 776 | log(msg); |
f49bc4f7 | 777 | error("Exiting, you have requested strict checking."); |
778 | goto fail; | |
7c49df64 | 779 | } else if (options.strict_host_key_checking == 2) { |
616a6b93 | 780 | strlcat(msg, "\nAre you sure you want " |
781 | "to continue connecting (yes/no)? ", sizeof(msg)); | |
782 | if (!confirm(msg)) | |
f49bc4f7 | 783 | goto fail; |
616a6b93 | 784 | } else { |
785 | log(msg); | |
7c49df64 | 786 | } |
787 | } | |
788 | ||
0b6fbf03 | 789 | xfree(ip); |
f49bc4f7 | 790 | return 0; |
791 | ||
792 | fail: | |
793 | xfree(ip); | |
794 | return -1; | |
795 | } | |
796 | ||
797 | int | |
798 | verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) | |
799 | { | |
800 | struct stat st; | |
801 | ||
802 | /* return ok if the key can be found in an old keyfile */ | |
803 | if (stat(options.system_hostfile2, &st) == 0 || | |
804 | stat(options.user_hostfile2, &st) == 0) { | |
805 | if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1, | |
806 | options.user_hostfile2, options.system_hostfile2) == 0) | |
807 | return 0; | |
808 | } | |
809 | return check_host_key(host, hostaddr, host_key, /*readonly*/ 0, | |
810 | options.user_hostfile, options.system_hostfile); | |
95f1eccc | 811 | } |
812 | ||
8ce64345 | 813 | /* |
a306f2dd | 814 | * Starts a dialog with the server, and authenticates the current user on the |
815 | * server. This does not need any extra privileges. The basic connection | |
816 | * to the server must already have been established before this is called. | |
817 | * If login fails, this function prints an error and never returns. | |
818 | * This function does not require super-user privileges. | |
8ce64345 | 819 | */ |
820 | void | |
39c00dc2 | 821 | ssh_login(Sensitive *sensitive, const char *orighost, |
63bd8c36 | 822 | struct sockaddr *hostaddr, struct passwd *pw) |
8ce64345 | 823 | { |
a306f2dd | 824 | char *host, *cp; |
8ce64345 | 825 | char *server_user, *local_user; |
8ce64345 | 826 | |
8ce64345 | 827 | local_user = xstrdup(pw->pw_name); |
828 | server_user = options.user ? options.user : local_user; | |
829 | ||
7b2ea3a1 | 830 | /* Convert the user-supplied hostname into all lowercase. */ |
831 | host = xstrdup(orighost); | |
832 | for (cp = host; *cp; cp++) | |
833 | if (isupper(*cp)) | |
834 | *cp = tolower(*cp); | |
835 | ||
836 | /* Exchange protocol version identification strings with the server. */ | |
837 | ssh_exchange_identification(); | |
838 | ||
839 | /* Put the connection into non-blocking mode. */ | |
840 | packet_set_nonblocking(); | |
841 | ||
7b2ea3a1 | 842 | /* key exchange */ |
7b2ea3a1 | 843 | /* authenticate user */ |
8ce64345 | 844 | if (compat20) { |
845 | ssh_kex2(host, hostaddr); | |
39c00dc2 | 846 | ssh_userauth2(local_user, server_user, host, sensitive); |
8ce64345 | 847 | } else { |
8ce64345 | 848 | ssh_kex(host, hostaddr); |
39c00dc2 | 849 | ssh_userauth1(local_user, server_user, host, sensitive); |
8ce64345 | 850 | } |
7b2ea3a1 | 851 | } |
0ae4fe1d | 852 | |
853 | void | |
854 | ssh_put_password(char *password) | |
855 | { | |
856 | int size; | |
857 | char *padded; | |
858 | ||
99c415db | 859 | if (datafellows & SSH_BUG_PASSWORDPAD) { |
449c5ba5 | 860 | packet_put_cstring(password); |
99c415db | 861 | return; |
862 | } | |
0ae4fe1d | 863 | size = roundup(strlen(password) + 1, 32); |
864 | padded = xmalloc(size); | |
865 | memset(padded, 0, size); | |
866 | strlcpy(padded, password, size); | |
867 | packet_put_string(padded, size); | |
868 | memset(padded, 0, size); | |
869 | xfree(padded); | |
870 | } |