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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" | |
39c00dc2 | 16 | RCSID("$OpenBSD: sshconnect.c,v 1.120 2002/05/23 19:24:30 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 | |
57112b5a | 39 | extern Options options; |
48e671d5 | 40 | extern char *__progname; |
57112b5a | 41 | |
a704dd54 | 42 | #ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */ |
43 | #define INET6_ADDRSTRLEN 46 | |
44 | #endif | |
45 | ||
ce773142 | 46 | static const char * |
47 | sockaddr_ntop(struct sockaddr *sa) | |
48 | { | |
49 | void *addr; | |
50 | static char addrbuf[INET6_ADDRSTRLEN]; | |
51 | ||
52 | switch (sa->sa_family) { | |
6aacefa7 | 53 | case AF_INET: |
54 | addr = &((struct sockaddr_in *)sa)->sin_addr; | |
55 | break; | |
56 | case AF_INET6: | |
57 | addr = &((struct sockaddr_in6 *)sa)->sin6_addr; | |
58 | break; | |
59 | default: | |
60 | /* This case should be protected against elsewhere */ | |
61 | abort(); /* XXX abort is bad -- do something else */ | |
ce773142 | 62 | } |
63 | inet_ntop(sa->sa_family, addr, addrbuf, sizeof(addrbuf)); | |
64 | return addrbuf; | |
65 | } | |
66 | ||
5260325f | 67 | /* |
68 | * Connect to the given ssh server using a proxy command. | |
69 | */ | |
396c147e | 70 | static int |
63bd8c36 | 71 | ssh_proxy_connect(const char *host, u_short port, struct passwd *pw, |
8efc0c15 | 72 | const char *proxy_command) |
73 | { | |
5260325f | 74 | Buffer command; |
75 | const char *cp; | |
76 | char *command_string; | |
77 | int pin[2], pout[2]; | |
9da5c3c9 | 78 | pid_t pid; |
48e671d5 | 79 | char strport[NI_MAXSERV]; |
5260325f | 80 | |
81 | /* Convert the port number into a string. */ | |
48e671d5 | 82 | snprintf(strport, sizeof strport, "%hu", port); |
5260325f | 83 | |
84 | /* Build the final command string in the buffer by making the | |
85 | appropriate substitutions to the given proxy command. */ | |
86 | buffer_init(&command); | |
87 | for (cp = proxy_command; *cp; cp++) { | |
88 | if (cp[0] == '%' && cp[1] == '%') { | |
89 | buffer_append(&command, "%", 1); | |
90 | cp++; | |
91 | continue; | |
92 | } | |
93 | if (cp[0] == '%' && cp[1] == 'h') { | |
94 | buffer_append(&command, host, strlen(host)); | |
95 | cp++; | |
96 | continue; | |
97 | } | |
98 | if (cp[0] == '%' && cp[1] == 'p') { | |
48e671d5 | 99 | buffer_append(&command, strport, strlen(strport)); |
5260325f | 100 | cp++; |
101 | continue; | |
102 | } | |
103 | buffer_append(&command, cp, 1); | |
8efc0c15 | 104 | } |
5260325f | 105 | buffer_append(&command, "\0", 1); |
106 | ||
107 | /* Get the final command string. */ | |
108 | command_string = buffer_ptr(&command); | |
109 | ||
110 | /* Create pipes for communicating with the proxy. */ | |
111 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
112 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
184eed6a | 113 | strerror(errno)); |
5260325f | 114 | |
115 | debug("Executing proxy command: %.500s", command_string); | |
116 | ||
117 | /* Fork and execute the proxy command. */ | |
118 | if ((pid = fork()) == 0) { | |
119 | char *argv[10]; | |
120 | ||
121 | /* Child. Permanently give up superuser privileges. */ | |
63bd8c36 | 122 | permanently_set_uid(pw); |
5260325f | 123 | |
124 | /* Redirect stdin and stdout. */ | |
125 | close(pin[1]); | |
126 | if (pin[0] != 0) { | |
127 | if (dup2(pin[0], 0) < 0) | |
128 | perror("dup2 stdin"); | |
129 | close(pin[0]); | |
130 | } | |
131 | close(pout[0]); | |
132 | if (dup2(pout[1], 1) < 0) | |
133 | perror("dup2 stdout"); | |
134 | /* Cannot be 1 because pin allocated two descriptors. */ | |
135 | close(pout[1]); | |
136 | ||
137 | /* Stderr is left as it is so that error messages get | |
138 | printed on the user's terminal. */ | |
30228d7c | 139 | argv[0] = _PATH_BSHELL; |
5260325f | 140 | argv[1] = "-c"; |
141 | argv[2] = command_string; | |
142 | argv[3] = NULL; | |
143 | ||
144 | /* Execute the proxy command. Note that we gave up any | |
145 | extra privileges above. */ | |
328654d8 | 146 | execv(argv[0], argv); |
147 | perror(argv[0]); | |
5260325f | 148 | exit(1); |
8efc0c15 | 149 | } |
5260325f | 150 | /* Parent. */ |
151 | if (pid < 0) | |
152 | fatal("fork failed: %.100s", strerror(errno)); | |
153 | ||
154 | /* Close child side of the descriptors. */ | |
155 | close(pin[0]); | |
156 | close(pout[1]); | |
157 | ||
158 | /* Free the command name. */ | |
159 | buffer_free(&command); | |
160 | ||
161 | /* Set the connection file descriptors. */ | |
162 | packet_set_connection(pout[0], pin[1]); | |
8efc0c15 | 163 | |
ce773142 | 164 | /* Indicate OK return */ |
165 | return 0; | |
5260325f | 166 | } |
8efc0c15 | 167 | |
5260325f | 168 | /* |
169 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
170 | */ | |
396c147e | 171 | static int |
63bd8c36 | 172 | ssh_create_socket(struct passwd *pw, int privileged, int family) |
8efc0c15 | 173 | { |
3435f5a6 | 174 | int sock, gaierr; |
175 | struct addrinfo hints, *res; | |
5260325f | 176 | |
aa3378df | 177 | /* |
178 | * If we are running as root and want to connect to a privileged | |
179 | * port, bind our own socket to a privileged port. | |
180 | */ | |
5260325f | 181 | if (privileged) { |
182 | int p = IPPORT_RESERVED - 1; | |
48e671d5 | 183 | sock = rresvport_af(&p, family); |
5260325f | 184 | if (sock < 0) |
c8d54615 | 185 | error("rresvport: af=%d %.100s", family, strerror(errno)); |
186 | else | |
187 | debug("Allocated local port %d.", p); | |
3435f5a6 | 188 | return sock; |
189 | } | |
190 | /* | |
191 | * Just create an ordinary socket on arbitrary port. We use | |
192 | * the user's uid to create the socket. | |
193 | */ | |
194 | temporarily_use_uid(pw); | |
195 | sock = socket(family, SOCK_STREAM, 0); | |
196 | if (sock < 0) | |
197 | error("socket: %.100s", strerror(errno)); | |
198 | restore_uid(); | |
199 | ||
200 | /* Bind the socket to an alternative local IP address */ | |
201 | if (options.bind_address == NULL) | |
202 | return sock; | |
203 | ||
204 | memset(&hints, 0, sizeof(hints)); | |
32af6a3f | 205 | hints.ai_family = family; |
3435f5a6 | 206 | hints.ai_socktype = SOCK_STREAM; |
207 | hints.ai_flags = AI_PASSIVE; | |
208 | gaierr = getaddrinfo(options.bind_address, "0", &hints, &res); | |
209 | if (gaierr) { | |
210 | error("getaddrinfo: %s: %s", options.bind_address, | |
211 | gai_strerror(gaierr)); | |
212 | close(sock); | |
213 | return -1; | |
214 | } | |
215 | if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { | |
216 | error("bind: %s: %s", options.bind_address, strerror(errno)); | |
217 | close(sock); | |
218 | freeaddrinfo(res); | |
219 | return -1; | |
5260325f | 220 | } |
3435f5a6 | 221 | freeaddrinfo(res); |
5260325f | 222 | return sock; |
8efc0c15 | 223 | } |
224 | ||
5260325f | 225 | /* |
48e671d5 | 226 | * Opens a TCP/IP connection to the remote server on the given host. |
227 | * The address of the remote host will be returned in hostaddr. | |
228 | * If port is 0, the default port will be used. If anonymous is zero, | |
5260325f | 229 | * a privileged port will be allocated to make the connection. |
230 | * This requires super-user privileges if anonymous is false. | |
231 | * Connection_attempts specifies the maximum number of tries (one per | |
232 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
233 | * and %p substituted for host and port, respectively) to use to contact | |
234 | * the daemon. | |
ce773142 | 235 | * Return values: |
236 | * 0 for OK | |
237 | * ECONNREFUSED if we got a "Connection Refused" by the peer on any address | |
238 | * ECONNABORTED if we failed without a "Connection refused" | |
239 | * Suitable error messages for the connection failure will already have been | |
240 | * printed. | |
5260325f | 241 | */ |
242 | int | |
48e671d5 | 243 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, |
dab89049 | 244 | u_short port, int family, int connection_attempts, |
245 | int anonymous, struct passwd *pw, const char *proxy_command) | |
8efc0c15 | 246 | { |
b5c334cc | 247 | int gaierr; |
248 | int on = 1; | |
48e671d5 | 249 | int sock = -1, attempt; |
48e671d5 | 250 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; |
b5c334cc | 251 | struct addrinfo hints, *ai, *aitop; |
5260325f | 252 | struct linger linger; |
b5c334cc | 253 | struct servent *sp; |
ce773142 | 254 | /* |
255 | * Did we get only other errors than "Connection refused" (which | |
256 | * should block fallback to rsh and similar), or did we get at least | |
257 | * one "Connection refused"? | |
258 | */ | |
259 | int full_failure = 1; | |
5260325f | 260 | |
14a9a859 | 261 | debug("ssh_connect: getuid %u geteuid %u anon %d", |
184eed6a | 262 | (u_int) getuid(), (u_int) geteuid(), anonymous); |
5260325f | 263 | |
264 | /* Get default port if port has not been set. */ | |
265 | if (port == 0) { | |
266 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
267 | if (sp) | |
268 | port = ntohs(sp->s_port); | |
269 | else | |
270 | port = SSH_DEFAULT_PORT; | |
8efc0c15 | 271 | } |
5260325f | 272 | /* If a proxy command is given, connect using it. */ |
273 | if (proxy_command != NULL) | |
63bd8c36 | 274 | return ssh_proxy_connect(host, port, pw, proxy_command); |
5260325f | 275 | |
276 | /* No proxy command. */ | |
277 | ||
48e671d5 | 278 | memset(&hints, 0, sizeof(hints)); |
dab89049 | 279 | hints.ai_family = family; |
48e671d5 | 280 | hints.ai_socktype = SOCK_STREAM; |
281 | snprintf(strport, sizeof strport, "%d", port); | |
282 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) | |
283 | fatal("%s: %.100s: %s", __progname, host, | |
284 | gai_strerror(gaierr)); | |
5260325f | 285 | |
95f1eccc | 286 | /* |
287 | * Try to connect several times. On some machines, the first time | |
288 | * will sometimes fail. In general socket code appears to behave | |
289 | * quite magically on many machines. | |
ce773142 | 290 | */ |
291 | for (attempt = 0; ;) { | |
5260325f | 292 | if (attempt > 0) |
293 | debug("Trying again..."); | |
294 | ||
48e671d5 | 295 | /* Loop through addresses for this host, and try each one in |
6ae2364d | 296 | sequence until the connection succeeds. */ |
48e671d5 | 297 | for (ai = aitop; ai; ai = ai->ai_next) { |
298 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
299 | continue; | |
300 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
301 | ntop, sizeof(ntop), strport, sizeof(strport), | |
302 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
303 | error("ssh_connect: getnameinfo failed"); | |
304 | continue; | |
305 | } | |
306 | debug("Connecting to %.200s [%.100s] port %s.", | |
307 | host, ntop, strport); | |
308 | ||
309 | /* Create a socket for connecting. */ | |
63bd8c36 | 310 | sock = ssh_create_socket(pw, |
3c62e7eb | 311 | #ifdef HAVE_CYGWIN |
fa08c86b | 312 | !anonymous, |
3c62e7eb | 313 | #else |
fa08c86b | 314 | !anonymous && geteuid() == 0, |
3c62e7eb | 315 | #endif |
48e671d5 | 316 | ai->ai_family); |
317 | if (sock < 0) | |
ce773142 | 318 | /* Any error is already output */ |
48e671d5 | 319 | continue; |
320 | ||
321 | /* Connect to the host. We use the user's uid in the | |
322 | * hope that it will help with tcp_wrappers showing | |
323 | * the remote uid as root. | |
aa3378df | 324 | */ |
63bd8c36 | 325 | temporarily_use_uid(pw); |
48e671d5 | 326 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { |
327 | /* Successful connection. */ | |
cd332296 | 328 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); |
5260325f | 329 | restore_uid(); |
330 | break; | |
48e671d5 | 331 | } else { |
ce773142 | 332 | if (errno == ECONNREFUSED) |
333 | full_failure = 0; | |
334 | log("ssh: connect to address %s port %s: %s", | |
335 | sockaddr_ntop(ai->ai_addr), strport, | |
336 | strerror(errno)); | |
5260325f | 337 | restore_uid(); |
aa3378df | 338 | /* |
339 | * Close the failed socket; there appear to | |
340 | * be some problems when reusing a socket for | |
341 | * which connect() has already returned an | |
342 | * error. | |
343 | */ | |
5260325f | 344 | close(sock); |
345 | } | |
8efc0c15 | 346 | } |
48e671d5 | 347 | if (ai) |
348 | break; /* Successful connection. */ | |
8efc0c15 | 349 | |
ce773142 | 350 | attempt++; |
351 | if (attempt >= connection_attempts) | |
352 | break; | |
5260325f | 353 | /* Sleep a moment before retrying. */ |
354 | sleep(1); | |
355 | } | |
48e671d5 | 356 | |
357 | freeaddrinfo(aitop); | |
358 | ||
5260325f | 359 | /* Return failure if we didn't get a successful connection. */ |
360 | if (attempt >= connection_attempts) | |
ce773142 | 361 | return full_failure ? ECONNABORTED : ECONNREFUSED; |
8efc0c15 | 362 | |
5260325f | 363 | debug("Connection established."); |
8efc0c15 | 364 | |
aa3378df | 365 | /* |
366 | * Set socket options. We would like the socket to disappear as soon | |
367 | * as it has been closed for whatever reason. | |
368 | */ | |
369 | /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 370 | linger.l_onoff = 1; |
371 | linger.l_linger = 5; | |
b5c334cc | 372 | setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger)); |
373 | ||
374 | /* Set keepalives if requested. */ | |
375 | if (options.keepalives && | |
376 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, | |
377 | sizeof(on)) < 0) | |
378 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
8efc0c15 | 379 | |
5260325f | 380 | /* Set the connection. */ |
381 | packet_set_connection(sock, sock); | |
8efc0c15 | 382 | |
ce773142 | 383 | return 0; |
8efc0c15 | 384 | } |
385 | ||
5260325f | 386 | /* |
387 | * Waits for the server identification string, and sends our own | |
388 | * identification string. | |
389 | */ | |
396c147e | 390 | static void |
5ca51e19 | 391 | ssh_exchange_identification(void) |
8efc0c15 | 392 | { |
5260325f | 393 | char buf[256], remote_version[256]; /* must be same size! */ |
a8be9f80 | 394 | int remote_major, remote_minor, i, mismatch; |
5260325f | 395 | int connection_in = packet_get_connection_in(); |
396 | int connection_out = packet_get_connection_out(); | |
2b87da3b | 397 | int minor1 = PROTOCOL_MINOR_1; |
5260325f | 398 | |
399 | /* Read other side\'s version identification. */ | |
38c295d6 | 400 | for (;;) { |
401 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
402 | int len = atomicio(read, connection_in, &buf[i], 1); | |
403 | if (len < 0) | |
404 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); | |
405 | if (len != 1) | |
406 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
407 | if (buf[i] == '\r') { | |
408 | buf[i] = '\n'; | |
409 | buf[i + 1] = 0; | |
410 | continue; /**XXX wait for \n */ | |
411 | } | |
412 | if (buf[i] == '\n') { | |
413 | buf[i + 1] = 0; | |
414 | break; | |
415 | } | |
5260325f | 416 | } |
38c295d6 | 417 | buf[sizeof(buf) - 1] = 0; |
418 | if (strncmp(buf, "SSH-", 4) == 0) | |
5260325f | 419 | break; |
38c295d6 | 420 | debug("ssh_exchange_identification: %s", buf); |
8efc0c15 | 421 | } |
8ce64345 | 422 | server_version_string = xstrdup(buf); |
5260325f | 423 | |
aa3378df | 424 | /* |
425 | * Check that the versions match. In future this might accept | |
426 | * several versions and set appropriate flags to handle them. | |
427 | */ | |
8ce64345 | 428 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", |
429 | &remote_major, &remote_minor, remote_version) != 3) | |
5260325f | 430 | fatal("Bad remote protocol version identification: '%.100s'", buf); |
431 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
184eed6a | 432 | remote_major, remote_minor, remote_version); |
5260325f | 433 | |
8ce64345 | 434 | compat_datafellows(remote_version); |
a8be9f80 | 435 | mismatch = 0; |
436 | ||
6aacefa7 | 437 | switch (remote_major) { |
a8be9f80 | 438 | case 1: |
439 | if (remote_minor == 99 && | |
440 | (options.protocol & SSH_PROTO_2) && | |
441 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
442 | enable_compat20(); | |
443 | break; | |
5260325f | 444 | } |
a8be9f80 | 445 | if (!(options.protocol & SSH_PROTO_1)) { |
446 | mismatch = 1; | |
447 | break; | |
448 | } | |
449 | if (remote_minor < 3) { | |
450 | fatal("Remote machine has too old SSH software version."); | |
fa08c86b | 451 | } else if (remote_minor == 3 || remote_minor == 4) { |
a8be9f80 | 452 | /* We speak 1.3, too. */ |
453 | enable_compat13(); | |
fa08c86b | 454 | minor1 = 3; |
a8be9f80 | 455 | if (options.forward_agent) { |
456 | log("Agent forwarding disabled for protocol 1.3"); | |
457 | options.forward_agent = 0; | |
458 | } | |
459 | } | |
460 | break; | |
461 | case 2: | |
462 | if (options.protocol & SSH_PROTO_2) { | |
463 | enable_compat20(); | |
464 | break; | |
465 | } | |
466 | /* FALLTHROUGH */ | |
6ae2364d | 467 | default: |
a8be9f80 | 468 | mismatch = 1; |
469 | break; | |
8efc0c15 | 470 | } |
a8be9f80 | 471 | if (mismatch) |
5260325f | 472 | fatal("Protocol major versions differ: %d vs. %d", |
a8be9f80 | 473 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
474 | remote_major); | |
5260325f | 475 | /* Send our own protocol version identification. */ |
476 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
a8be9f80 | 477 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
fa08c86b | 478 | compat20 ? PROTOCOL_MINOR_2 : minor1, |
8ce64345 | 479 | SSH_VERSION); |
a408af76 | 480 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) |
5260325f | 481 | fatal("write: %.100s", strerror(errno)); |
8ce64345 | 482 | client_version_string = xstrdup(buf); |
483 | chop(client_version_string); | |
484 | chop(server_version_string); | |
485 | debug("Local version string %.100s", client_version_string); | |
8efc0c15 | 486 | } |
487 | ||
f21032a6 | 488 | /* defaults to 'no' */ |
396c147e | 489 | static int |
a2c92c4a | 490 | confirm(const char *prompt) |
8efc0c15 | 491 | { |
616a6b93 | 492 | const char *msg, *again = "Please type 'yes' or 'no': "; |
493 | char *p; | |
494 | int ret = -1; | |
5260325f | 495 | |
f21032a6 | 496 | if (options.batch_mode) |
497 | return 0; | |
616a6b93 | 498 | for (msg = prompt;;msg = again) { |
499 | p = read_passphrase(msg, RP_ECHO); | |
500 | if (p == NULL || | |
501 | (p[0] == '\0') || (p[0] == '\n') || | |
502 | strncasecmp(p, "no", 2) == 0) | |
503 | ret = 0; | |
504 | if (strncasecmp(p, "yes", 3) == 0) | |
505 | ret = 1; | |
506 | if (p) | |
507 | xfree(p); | |
508 | if (ret != -1) | |
509 | return ret; | |
8efc0c15 | 510 | } |
8efc0c15 | 511 | } |
512 | ||
5260325f | 513 | /* |
f49bc4f7 | 514 | * check whether the supplied host key is valid, return -1 if the key |
515 | * is not valid. the user_hostfile will not be updated if 'readonly' is true. | |
5260325f | 516 | */ |
95f1eccc | 517 | |
396c147e | 518 | static int |
a306f2dd | 519 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, |
f49bc4f7 | 520 | int readonly, const char *user_hostfile, const char *system_hostfile) |
8efc0c15 | 521 | { |
4fe2af09 | 522 | Key *file_key; |
1d1ffb87 | 523 | char *type = key_type(host_key); |
95f1eccc | 524 | char *ip = NULL; |
22138a36 | 525 | char hostline[1000], *hostp, *fp; |
5260325f | 526 | HostStatus host_status; |
527 | HostStatus ip_status; | |
48e671d5 | 528 | int local = 0, host_ip_differ = 0; |
20af321f | 529 | int salen; |
48e671d5 | 530 | char ntop[NI_MAXHOST]; |
616a6b93 | 531 | char msg[1024]; |
532 | int len, host_line, ip_line; | |
1e3b8b07 | 533 | const char *host_file = NULL, *ip_file = NULL; |
48e671d5 | 534 | |
535 | /* | |
536 | * Force accepting of the host key for loopback/localhost. The | |
537 | * problem is that if the home directory is NFS-mounted to multiple | |
538 | * machines, localhost will refer to a different machine in each of | |
539 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
540 | * essentially disables host authentication for localhost; however, | |
541 | * this is probably not a real problem. | |
542 | */ | |
a306f2dd | 543 | /** hostaddr == 0! */ |
48e671d5 | 544 | switch (hostaddr->sa_family) { |
545 | case AF_INET: | |
f49bc4f7 | 546 | local = (ntohl(((struct sockaddr_in *)hostaddr)-> |
20a11d35 | 547 | sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; |
20af321f | 548 | salen = sizeof(struct sockaddr_in); |
48e671d5 | 549 | break; |
550 | case AF_INET6: | |
f49bc4f7 | 551 | local = IN6_IS_ADDR_LOOPBACK( |
552 | &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
20af321f | 553 | salen = sizeof(struct sockaddr_in6); |
48e671d5 | 554 | break; |
555 | default: | |
556 | local = 0; | |
20af321f | 557 | salen = sizeof(struct sockaddr_storage); |
48e671d5 | 558 | break; |
559 | } | |
8bbc048a | 560 | if (options.no_host_authentication_for_localhost == 1 && local && |
561 | options.host_key_alias == NULL) { | |
7c49df64 | 562 | debug("Forcing accepting of host key for " |
563 | "loopback/localhost."); | |
f49bc4f7 | 564 | return 0; |
48e671d5 | 565 | } |
5260325f | 566 | |
57112b5a | 567 | /* |
7c49df64 | 568 | * We don't have the remote ip-address for connections |
569 | * using a proxy command | |
570 | */ | |
571 | if (options.proxy_command == NULL) { | |
572 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), | |
573 | NULL, 0, NI_NUMERICHOST) != 0) | |
574 | fatal("check_host_key: getnameinfo failed"); | |
575 | ip = xstrdup(ntop); | |
576 | } else { | |
577 | ip = xstrdup("<no hostip for proxy command>"); | |
578 | } | |
579 | /* | |
580 | * Turn off check_host_ip if the connection is to localhost, via proxy | |
581 | * command or if we don't have a hostname to compare with | |
57112b5a | 582 | */ |
7c49df64 | 583 | if (options.check_host_ip && |
584 | (local || strcmp(host, ip) == 0 || options.proxy_command != NULL)) | |
57112b5a | 585 | options.check_host_ip = 0; |
586 | ||
8abcdba4 | 587 | /* |
7c49df64 | 588 | * Allow the user to record the key under a different name. This is |
8abcdba4 | 589 | * useful for ssh tunneling over forwarded connections or if you run |
7c49df64 | 590 | * multiple sshd's on different ports on the same machine. |
8abcdba4 | 591 | */ |
592 | if (options.host_key_alias != NULL) { | |
593 | host = options.host_key_alias; | |
594 | debug("using hostkeyalias: %s", host); | |
595 | } | |
596 | ||
95f1eccc | 597 | /* |
598 | * Store the host key from the known host file in here so that we can | |
599 | * compare it with the key for the IP address. | |
600 | */ | |
4fe2af09 | 601 | file_key = key_new(host_key->type); |
5260325f | 602 | |
aa3378df | 603 | /* |
604 | * Check if the host key is present in the user\'s list of known | |
605 | * hosts or in the systemwide list. | |
606 | */ | |
1e3b8b07 | 607 | host_file = user_hostfile; |
f49bc4f7 | 608 | host_status = check_host_in_hostfile(host_file, host, host_key, |
184eed6a | 609 | file_key, &host_line); |
1e3b8b07 | 610 | if (host_status == HOST_NEW) { |
611 | host_file = system_hostfile; | |
f49bc4f7 | 612 | host_status = check_host_in_hostfile(host_file, host, host_key, |
613 | file_key, &host_line); | |
1e3b8b07 | 614 | } |
aa3378df | 615 | /* |
616 | * Also perform check for the ip address, skip the check if we are | |
617 | * localhost or the hostname was an ip address to begin with | |
618 | */ | |
7c49df64 | 619 | if (options.check_host_ip) { |
4fe2af09 | 620 | Key *ip_key = key_new(host_key->type); |
5260325f | 621 | |
1e3b8b07 | 622 | ip_file = user_hostfile; |
f49bc4f7 | 623 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, |
624 | ip_key, &ip_line); | |
1e3b8b07 | 625 | if (ip_status == HOST_NEW) { |
626 | ip_file = system_hostfile; | |
f49bc4f7 | 627 | ip_status = check_host_in_hostfile(ip_file, ip, |
628 | host_key, ip_key, &ip_line); | |
1e3b8b07 | 629 | } |
5260325f | 630 | if (host_status == HOST_CHANGED && |
4fe2af09 | 631 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) |
5260325f | 632 | host_ip_differ = 1; |
633 | ||
4fe2af09 | 634 | key_free(ip_key); |
5260325f | 635 | } else |
636 | ip_status = host_status; | |
637 | ||
4fe2af09 | 638 | key_free(file_key); |
5260325f | 639 | |
640 | switch (host_status) { | |
641 | case HOST_OK: | |
642 | /* The host is known and the key matches. */ | |
1d1ffb87 | 643 | debug("Host '%.200s' is known and matches the %s host key.", |
644 | host, type); | |
1e3b8b07 | 645 | debug("Found key in %s:%d", host_file, host_line); |
7c49df64 | 646 | if (options.check_host_ip && ip_status == HOST_NEW) { |
f49bc4f7 | 647 | if (readonly) |
648 | log("%s host key for IP address " | |
649 | "'%.128s' not in list of known hosts.", | |
7c49df64 | 650 | type, ip); |
f49bc4f7 | 651 | else if (!add_host_to_hostfile(user_hostfile, ip, |
184eed6a | 652 | host_key)) |
f49bc4f7 | 653 | log("Failed to add the %s host key for IP " |
654 | "address '%.128s' to the list of known " | |
655 | "hosts (%.30s).", type, ip, user_hostfile); | |
656 | else | |
657 | log("Warning: Permanently added the %s host " | |
658 | "key for IP address '%.128s' to the list " | |
659 | "of known hosts.", type, ip); | |
5260325f | 660 | } |
661 | break; | |
662 | case HOST_NEW: | |
f49bc4f7 | 663 | if (readonly) |
664 | goto fail; | |
5260325f | 665 | /* The host is new. */ |
666 | if (options.strict_host_key_checking == 1) { | |
f49bc4f7 | 667 | /* |
668 | * User has requested strict host key checking. We | |
669 | * will not add the host key automatically. The only | |
670 | * alternative left is to abort. | |
671 | */ | |
672 | error("No %s host key is known for %.200s and you " | |
673 | "have requested strict checking.", type, host); | |
674 | goto fail; | |
5260325f | 675 | } else if (options.strict_host_key_checking == 2) { |
676 | /* The default */ | |
22138a36 | 677 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
616a6b93 | 678 | snprintf(msg, sizeof(msg), |
f49bc4f7 | 679 | "The authenticity of host '%.200s (%s)' can't be " |
680 | "established.\n" | |
1d1ffb87 | 681 | "%s key fingerprint is %s.\n" |
f49bc4f7 | 682 | "Are you sure you want to continue connecting " |
683 | "(yes/no)? ", host, ip, type, fp); | |
22138a36 | 684 | xfree(fp); |
616a6b93 | 685 | if (!confirm(msg)) |
f49bc4f7 | 686 | goto fail; |
5260325f | 687 | } |
7c49df64 | 688 | if (options.check_host_ip && ip_status == HOST_NEW) { |
5260325f | 689 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); |
690 | hostp = hostline; | |
691 | } else | |
692 | hostp = host; | |
693 | ||
f49bc4f7 | 694 | /* |
695 | * If not in strict mode, add the key automatically to the | |
696 | * local known_hosts file. | |
697 | */ | |
a306f2dd | 698 | if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) |
f49bc4f7 | 699 | log("Failed to add the host to the list of known " |
700 | "hosts (%.500s).", user_hostfile); | |
5260325f | 701 | else |
f49bc4f7 | 702 | log("Warning: Permanently added '%.200s' (%s) to the " |
703 | "list of known hosts.", hostp, type); | |
5260325f | 704 | break; |
705 | case HOST_CHANGED: | |
706 | if (options.check_host_ip && host_ip_differ) { | |
707 | char *msg; | |
708 | if (ip_status == HOST_NEW) | |
709 | msg = "is unknown"; | |
710 | else if (ip_status == HOST_OK) | |
711 | msg = "is unchanged"; | |
712 | else | |
713 | msg = "has a different value"; | |
714 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
715 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
716 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1d1ffb87 | 717 | error("The %s host key for %s has changed,", type, host); |
5260325f | 718 | error("and the key for the according IP address %s", ip); |
719 | error("%s. This could either mean that", msg); | |
720 | error("DNS SPOOFING is happening or the IP address for the host"); | |
1e3b8b07 | 721 | error("and its host key have changed at the same time."); |
7c49df64 | 722 | if (ip_status != HOST_NEW) |
1e3b8b07 | 723 | error("Offending key for IP in %s:%d", ip_file, ip_line); |
5260325f | 724 | } |
725 | /* The host key has changed. */ | |
22138a36 | 726 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
5260325f | 727 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
ae2f7af7 | 728 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); |
5260325f | 729 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
730 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
731 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
1d1ffb87 | 732 | error("It is also possible that the %s host key has just been changed.", type); |
8abcdba4 | 733 | error("The fingerprint for the %s key sent by the remote host is\n%s.", |
22138a36 | 734 | type, fp); |
5260325f | 735 | error("Please contact your system administrator."); |
736 | error("Add correct host key in %.100s to get rid of this message.", | |
8abcdba4 | 737 | user_hostfile); |
1e3b8b07 | 738 | error("Offending key in %s:%d", host_file, host_line); |
22138a36 | 739 | xfree(fp); |
5260325f | 740 | |
aa3378df | 741 | /* |
742 | * If strict host key checking is in use, the user will have | |
743 | * to edit the key manually and we can only abort. | |
744 | */ | |
f49bc4f7 | 745 | if (options.strict_host_key_checking) { |
746 | error("%s host key for %.200s has changed and you have " | |
747 | "requested strict checking.", type, host); | |
748 | goto fail; | |
749 | } | |
5260325f | 750 | |
aa3378df | 751 | /* |
752 | * If strict host key checking has not been requested, allow | |
753 | * the connection but without password authentication or | |
754 | * agent forwarding. | |
755 | */ | |
5260325f | 756 | if (options.password_authentication) { |
f49bc4f7 | 757 | error("Password authentication is disabled to avoid " |
758 | "man-in-the-middle attacks."); | |
5260325f | 759 | options.password_authentication = 0; |
760 | } | |
761 | if (options.forward_agent) { | |
f49bc4f7 | 762 | error("Agent forwarding is disabled to avoid " |
763 | "man-in-the-middle attacks."); | |
5260325f | 764 | options.forward_agent = 0; |
765 | } | |
0b6fbf03 | 766 | if (options.forward_x11) { |
f49bc4f7 | 767 | error("X11 forwarding is disabled to avoid " |
768 | "man-in-the-middle attacks."); | |
0b6fbf03 | 769 | options.forward_x11 = 0; |
770 | } | |
f49bc4f7 | 771 | if (options.num_local_forwards > 0 || |
772 | options.num_remote_forwards > 0) { | |
773 | error("Port forwarding is disabled to avoid " | |
774 | "man-in-the-middle attacks."); | |
775 | options.num_local_forwards = | |
184eed6a | 776 | options.num_remote_forwards = 0; |
0b6fbf03 | 777 | } |
aa3378df | 778 | /* |
779 | * XXX Should permit the user to change to use the new id. | |
780 | * This could be done by converting the host key to an | |
781 | * identifying sentence, tell that the host identifies itself | |
782 | * by that sentence, and ask the user if he/she whishes to | |
783 | * accept the authentication. | |
784 | */ | |
5260325f | 785 | break; |
786 | } | |
0b6fbf03 | 787 | |
7c49df64 | 788 | if (options.check_host_ip && host_status != HOST_CHANGED && |
789 | ip_status == HOST_CHANGED) { | |
616a6b93 | 790 | snprintf(msg, sizeof(msg), |
791 | "Warning: the %s host key for '%.200s' " | |
792 | "differs from the key for the IP address '%.128s'" | |
793 | "\nOffending key for IP in %s:%d", | |
794 | type, host, ip, ip_file, ip_line); | |
795 | if (host_status == HOST_OK) { | |
796 | len = strlen(msg); | |
797 | snprintf(msg + len, sizeof(msg) - len, | |
798 | "\nMatching host key in %s:%d", | |
799 | host_file, host_line); | |
800 | } | |
7c49df64 | 801 | if (options.strict_host_key_checking == 1) { |
616a6b93 | 802 | log(msg); |
f49bc4f7 | 803 | error("Exiting, you have requested strict checking."); |
804 | goto fail; | |
7c49df64 | 805 | } else if (options.strict_host_key_checking == 2) { |
616a6b93 | 806 | strlcat(msg, "\nAre you sure you want " |
807 | "to continue connecting (yes/no)? ", sizeof(msg)); | |
808 | if (!confirm(msg)) | |
f49bc4f7 | 809 | goto fail; |
616a6b93 | 810 | } else { |
811 | log(msg); | |
7c49df64 | 812 | } |
813 | } | |
814 | ||
0b6fbf03 | 815 | xfree(ip); |
f49bc4f7 | 816 | return 0; |
817 | ||
818 | fail: | |
819 | xfree(ip); | |
820 | return -1; | |
821 | } | |
822 | ||
823 | int | |
824 | verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) | |
825 | { | |
826 | struct stat st; | |
827 | ||
828 | /* return ok if the key can be found in an old keyfile */ | |
829 | if (stat(options.system_hostfile2, &st) == 0 || | |
830 | stat(options.user_hostfile2, &st) == 0) { | |
831 | if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1, | |
832 | options.user_hostfile2, options.system_hostfile2) == 0) | |
833 | return 0; | |
834 | } | |
835 | return check_host_key(host, hostaddr, host_key, /*readonly*/ 0, | |
836 | options.user_hostfile, options.system_hostfile); | |
95f1eccc | 837 | } |
838 | ||
8ce64345 | 839 | /* |
a306f2dd | 840 | * Starts a dialog with the server, and authenticates the current user on the |
841 | * server. This does not need any extra privileges. The basic connection | |
842 | * to the server must already have been established before this is called. | |
843 | * If login fails, this function prints an error and never returns. | |
844 | * This function does not require super-user privileges. | |
8ce64345 | 845 | */ |
846 | void | |
39c00dc2 | 847 | ssh_login(Sensitive *sensitive, const char *orighost, |
63bd8c36 | 848 | struct sockaddr *hostaddr, struct passwd *pw) |
8ce64345 | 849 | { |
a306f2dd | 850 | char *host, *cp; |
8ce64345 | 851 | char *server_user, *local_user; |
8ce64345 | 852 | |
8ce64345 | 853 | local_user = xstrdup(pw->pw_name); |
854 | server_user = options.user ? options.user : local_user; | |
855 | ||
7b2ea3a1 | 856 | /* Convert the user-supplied hostname into all lowercase. */ |
857 | host = xstrdup(orighost); | |
858 | for (cp = host; *cp; cp++) | |
859 | if (isupper(*cp)) | |
860 | *cp = tolower(*cp); | |
861 | ||
862 | /* Exchange protocol version identification strings with the server. */ | |
863 | ssh_exchange_identification(); | |
864 | ||
865 | /* Put the connection into non-blocking mode. */ | |
866 | packet_set_nonblocking(); | |
867 | ||
7b2ea3a1 | 868 | /* key exchange */ |
7b2ea3a1 | 869 | /* authenticate user */ |
8ce64345 | 870 | if (compat20) { |
871 | ssh_kex2(host, hostaddr); | |
39c00dc2 | 872 | ssh_userauth2(local_user, server_user, host, sensitive); |
8ce64345 | 873 | } else { |
8ce64345 | 874 | ssh_kex(host, hostaddr); |
39c00dc2 | 875 | ssh_userauth1(local_user, server_user, host, sensitive); |
8ce64345 | 876 | } |
7b2ea3a1 | 877 | } |
0ae4fe1d | 878 | |
879 | void | |
880 | ssh_put_password(char *password) | |
881 | { | |
882 | int size; | |
883 | char *padded; | |
884 | ||
99c415db | 885 | if (datafellows & SSH_BUG_PASSWORDPAD) { |
449c5ba5 | 886 | packet_put_cstring(password); |
99c415db | 887 | return; |
888 | } | |
0ae4fe1d | 889 | size = roundup(strlen(password) + 1, 32); |
890 | padded = xmalloc(size); | |
891 | memset(padded, 0, size); | |
892 | strlcpy(padded, password, size); | |
893 | packet_put_string(padded, size); | |
894 | memset(padded, 0, size); | |
895 | xfree(padded); | |
896 | } |