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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" | |
01ca0dfe | 16 | RCSID("$OpenBSD: sshconnect.c,v 1.123 2002/06/09 22:17:21 itojun 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 * |
01ca0dfe | 47 | sockaddr_ntop(struct sockaddr *sa, socklen_t salen) |
ce773142 | 48 | { |
35ad6a0a | 49 | static char addrbuf[NI_MAXHOST]; |
ce773142 | 50 | |
01ca0dfe | 51 | if (getnameinfo(sa, salen, addrbuf, sizeof(addrbuf), NULL, 0, |
35ad6a0a | 52 | NI_NUMERICHOST) != 0) |
b0ff7493 | 53 | fatal("sockaddr_ntop: getnameinfo NI_NUMERICHOST failed"); |
ce773142 | 54 | return addrbuf; |
55 | } | |
56 | ||
5260325f | 57 | /* |
58 | * Connect to the given ssh server using a proxy command. | |
59 | */ | |
396c147e | 60 | static int |
63bd8c36 | 61 | ssh_proxy_connect(const char *host, u_short port, struct passwd *pw, |
8efc0c15 | 62 | const char *proxy_command) |
63 | { | |
5260325f | 64 | Buffer command; |
65 | const char *cp; | |
66 | char *command_string; | |
67 | int pin[2], pout[2]; | |
9da5c3c9 | 68 | pid_t pid; |
48e671d5 | 69 | char strport[NI_MAXSERV]; |
5260325f | 70 | |
71 | /* Convert the port number into a string. */ | |
48e671d5 | 72 | snprintf(strport, sizeof strport, "%hu", port); |
5260325f | 73 | |
74 | /* Build the final command string in the buffer by making the | |
75 | appropriate substitutions to the given proxy command. */ | |
76 | buffer_init(&command); | |
77 | for (cp = proxy_command; *cp; cp++) { | |
78 | if (cp[0] == '%' && cp[1] == '%') { | |
79 | buffer_append(&command, "%", 1); | |
80 | cp++; | |
81 | continue; | |
82 | } | |
83 | if (cp[0] == '%' && cp[1] == 'h') { | |
84 | buffer_append(&command, host, strlen(host)); | |
85 | cp++; | |
86 | continue; | |
87 | } | |
88 | if (cp[0] == '%' && cp[1] == 'p') { | |
48e671d5 | 89 | buffer_append(&command, strport, strlen(strport)); |
5260325f | 90 | cp++; |
91 | continue; | |
92 | } | |
93 | buffer_append(&command, cp, 1); | |
8efc0c15 | 94 | } |
5260325f | 95 | buffer_append(&command, "\0", 1); |
96 | ||
97 | /* Get the final command string. */ | |
98 | command_string = buffer_ptr(&command); | |
99 | ||
100 | /* Create pipes for communicating with the proxy. */ | |
101 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
102 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
184eed6a | 103 | strerror(errno)); |
5260325f | 104 | |
105 | debug("Executing proxy command: %.500s", command_string); | |
106 | ||
107 | /* Fork and execute the proxy command. */ | |
108 | if ((pid = fork()) == 0) { | |
109 | char *argv[10]; | |
110 | ||
111 | /* Child. Permanently give up superuser privileges. */ | |
63bd8c36 | 112 | permanently_set_uid(pw); |
5260325f | 113 | |
114 | /* Redirect stdin and stdout. */ | |
115 | close(pin[1]); | |
116 | if (pin[0] != 0) { | |
117 | if (dup2(pin[0], 0) < 0) | |
118 | perror("dup2 stdin"); | |
119 | close(pin[0]); | |
120 | } | |
121 | close(pout[0]); | |
122 | if (dup2(pout[1], 1) < 0) | |
123 | perror("dup2 stdout"); | |
124 | /* Cannot be 1 because pin allocated two descriptors. */ | |
125 | close(pout[1]); | |
126 | ||
127 | /* Stderr is left as it is so that error messages get | |
128 | printed on the user's terminal. */ | |
30228d7c | 129 | argv[0] = _PATH_BSHELL; |
5260325f | 130 | argv[1] = "-c"; |
131 | argv[2] = command_string; | |
132 | argv[3] = NULL; | |
133 | ||
134 | /* Execute the proxy command. Note that we gave up any | |
135 | extra privileges above. */ | |
328654d8 | 136 | execv(argv[0], argv); |
137 | perror(argv[0]); | |
5260325f | 138 | exit(1); |
8efc0c15 | 139 | } |
5260325f | 140 | /* Parent. */ |
141 | if (pid < 0) | |
142 | fatal("fork failed: %.100s", strerror(errno)); | |
143 | ||
144 | /* Close child side of the descriptors. */ | |
145 | close(pin[0]); | |
146 | close(pout[1]); | |
147 | ||
148 | /* Free the command name. */ | |
149 | buffer_free(&command); | |
150 | ||
151 | /* Set the connection file descriptors. */ | |
152 | packet_set_connection(pout[0], pin[1]); | |
8efc0c15 | 153 | |
ce773142 | 154 | /* Indicate OK return */ |
155 | return 0; | |
5260325f | 156 | } |
8efc0c15 | 157 | |
5260325f | 158 | /* |
159 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
160 | */ | |
396c147e | 161 | static int |
63bd8c36 | 162 | ssh_create_socket(struct passwd *pw, int privileged, int family) |
8efc0c15 | 163 | { |
3435f5a6 | 164 | int sock, gaierr; |
165 | struct addrinfo hints, *res; | |
5260325f | 166 | |
aa3378df | 167 | /* |
168 | * If we are running as root and want to connect to a privileged | |
169 | * port, bind our own socket to a privileged port. | |
170 | */ | |
5260325f | 171 | if (privileged) { |
172 | int p = IPPORT_RESERVED - 1; | |
48e671d5 | 173 | sock = rresvport_af(&p, family); |
5260325f | 174 | if (sock < 0) |
c8d54615 | 175 | error("rresvport: af=%d %.100s", family, strerror(errno)); |
176 | else | |
177 | debug("Allocated local port %d.", p); | |
3435f5a6 | 178 | return sock; |
179 | } | |
180 | /* | |
181 | * Just create an ordinary socket on arbitrary port. We use | |
182 | * the user's uid to create the socket. | |
183 | */ | |
184 | temporarily_use_uid(pw); | |
185 | sock = socket(family, SOCK_STREAM, 0); | |
186 | if (sock < 0) | |
187 | error("socket: %.100s", strerror(errno)); | |
188 | restore_uid(); | |
189 | ||
190 | /* Bind the socket to an alternative local IP address */ | |
191 | if (options.bind_address == NULL) | |
192 | return sock; | |
193 | ||
194 | memset(&hints, 0, sizeof(hints)); | |
32af6a3f | 195 | hints.ai_family = family; |
3435f5a6 | 196 | hints.ai_socktype = SOCK_STREAM; |
197 | hints.ai_flags = AI_PASSIVE; | |
198 | gaierr = getaddrinfo(options.bind_address, "0", &hints, &res); | |
199 | if (gaierr) { | |
200 | error("getaddrinfo: %s: %s", options.bind_address, | |
201 | gai_strerror(gaierr)); | |
202 | close(sock); | |
203 | return -1; | |
204 | } | |
205 | if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { | |
206 | error("bind: %s: %s", options.bind_address, strerror(errno)); | |
207 | close(sock); | |
208 | freeaddrinfo(res); | |
209 | return -1; | |
5260325f | 210 | } |
3435f5a6 | 211 | freeaddrinfo(res); |
5260325f | 212 | return sock; |
8efc0c15 | 213 | } |
214 | ||
5260325f | 215 | /* |
48e671d5 | 216 | * Opens a TCP/IP connection to the remote server on the given host. |
217 | * The address of the remote host will be returned in hostaddr. | |
218 | * If port is 0, the default port will be used. If anonymous is zero, | |
5260325f | 219 | * a privileged port will be allocated to make the connection. |
220 | * This requires super-user privileges if anonymous is false. | |
221 | * Connection_attempts specifies the maximum number of tries (one per | |
222 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
223 | * and %p substituted for host and port, respectively) to use to contact | |
224 | * the daemon. | |
ce773142 | 225 | * Return values: |
226 | * 0 for OK | |
227 | * ECONNREFUSED if we got a "Connection Refused" by the peer on any address | |
228 | * ECONNABORTED if we failed without a "Connection refused" | |
229 | * Suitable error messages for the connection failure will already have been | |
230 | * printed. | |
5260325f | 231 | */ |
232 | int | |
48e671d5 | 233 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, |
dab89049 | 234 | u_short port, int family, int connection_attempts, |
235 | int anonymous, struct passwd *pw, const char *proxy_command) | |
8efc0c15 | 236 | { |
b5c334cc | 237 | int gaierr; |
238 | int on = 1; | |
48e671d5 | 239 | int sock = -1, attempt; |
48e671d5 | 240 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; |
b5c334cc | 241 | struct addrinfo hints, *ai, *aitop; |
5260325f | 242 | struct linger linger; |
b5c334cc | 243 | struct servent *sp; |
ce773142 | 244 | /* |
245 | * Did we get only other errors than "Connection refused" (which | |
246 | * should block fallback to rsh and similar), or did we get at least | |
247 | * one "Connection refused"? | |
248 | */ | |
249 | int full_failure = 1; | |
5260325f | 250 | |
14a9a859 | 251 | debug("ssh_connect: getuid %u geteuid %u anon %d", |
184eed6a | 252 | (u_int) getuid(), (u_int) geteuid(), anonymous); |
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) | |
63bd8c36 | 264 | return ssh_proxy_connect(host, port, pw, 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; |
271 | snprintf(strport, sizeof strport, "%d", port); | |
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. */ | |
63bd8c36 | 300 | sock = ssh_create_socket(pw, |
3c62e7eb | 301 | #ifdef HAVE_CYGWIN |
fa08c86b | 302 | !anonymous, |
3c62e7eb | 303 | #else |
fa08c86b | 304 | !anonymous && geteuid() == 0, |
3c62e7eb | 305 | #endif |
48e671d5 | 306 | ai->ai_family); |
307 | if (sock < 0) | |
ce773142 | 308 | /* Any error is already output */ |
48e671d5 | 309 | continue; |
310 | ||
311 | /* Connect to the host. We use the user's uid in the | |
312 | * hope that it will help with tcp_wrappers showing | |
313 | * the remote uid as root. | |
aa3378df | 314 | */ |
63bd8c36 | 315 | temporarily_use_uid(pw); |
48e671d5 | 316 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { |
317 | /* Successful connection. */ | |
cd332296 | 318 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); |
5260325f | 319 | restore_uid(); |
320 | break; | |
48e671d5 | 321 | } else { |
ce773142 | 322 | if (errno == ECONNREFUSED) |
323 | full_failure = 0; | |
324 | log("ssh: connect to address %s port %s: %s", | |
01ca0dfe | 325 | sockaddr_ntop(ai->ai_addr, ai->ai_addrlen), |
326 | strport, strerror(errno)); | |
5260325f | 327 | restore_uid(); |
aa3378df | 328 | /* |
329 | * Close the failed socket; there appear to | |
330 | * be some problems when reusing a socket for | |
331 | * which connect() has already returned an | |
332 | * error. | |
333 | */ | |
5260325f | 334 | close(sock); |
335 | } | |
8efc0c15 | 336 | } |
48e671d5 | 337 | if (ai) |
338 | break; /* Successful connection. */ | |
8efc0c15 | 339 | |
ce773142 | 340 | attempt++; |
341 | if (attempt >= connection_attempts) | |
342 | break; | |
5260325f | 343 | /* Sleep a moment before retrying. */ |
344 | sleep(1); | |
345 | } | |
48e671d5 | 346 | |
347 | freeaddrinfo(aitop); | |
348 | ||
5260325f | 349 | /* Return failure if we didn't get a successful connection. */ |
350 | if (attempt >= connection_attempts) | |
ce773142 | 351 | return full_failure ? ECONNABORTED : ECONNREFUSED; |
8efc0c15 | 352 | |
5260325f | 353 | debug("Connection established."); |
8efc0c15 | 354 | |
aa3378df | 355 | /* |
356 | * Set socket options. We would like the socket to disappear as soon | |
357 | * as it has been closed for whatever reason. | |
358 | */ | |
359 | /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 360 | linger.l_onoff = 1; |
361 | linger.l_linger = 5; | |
b5c334cc | 362 | setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger)); |
363 | ||
364 | /* Set keepalives if requested. */ | |
365 | if (options.keepalives && | |
366 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, | |
367 | sizeof(on)) < 0) | |
368 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
8efc0c15 | 369 | |
5260325f | 370 | /* Set the connection. */ |
371 | packet_set_connection(sock, sock); | |
8efc0c15 | 372 | |
ce773142 | 373 | return 0; |
8efc0c15 | 374 | } |
375 | ||
5260325f | 376 | /* |
377 | * Waits for the server identification string, and sends our own | |
378 | * identification string. | |
379 | */ | |
396c147e | 380 | static void |
5ca51e19 | 381 | ssh_exchange_identification(void) |
8efc0c15 | 382 | { |
5260325f | 383 | char buf[256], remote_version[256]; /* must be same size! */ |
a8be9f80 | 384 | int remote_major, remote_minor, i, mismatch; |
5260325f | 385 | int connection_in = packet_get_connection_in(); |
386 | int connection_out = packet_get_connection_out(); | |
2b87da3b | 387 | int minor1 = PROTOCOL_MINOR_1; |
5260325f | 388 | |
389 | /* Read other side\'s version identification. */ | |
38c295d6 | 390 | for (;;) { |
391 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
392 | int len = atomicio(read, connection_in, &buf[i], 1); | |
393 | if (len < 0) | |
394 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); | |
395 | if (len != 1) | |
396 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
397 | if (buf[i] == '\r') { | |
398 | buf[i] = '\n'; | |
399 | buf[i + 1] = 0; | |
400 | continue; /**XXX wait for \n */ | |
401 | } | |
402 | if (buf[i] == '\n') { | |
403 | buf[i + 1] = 0; | |
404 | break; | |
405 | } | |
5260325f | 406 | } |
38c295d6 | 407 | buf[sizeof(buf) - 1] = 0; |
408 | if (strncmp(buf, "SSH-", 4) == 0) | |
5260325f | 409 | break; |
38c295d6 | 410 | debug("ssh_exchange_identification: %s", buf); |
8efc0c15 | 411 | } |
8ce64345 | 412 | server_version_string = xstrdup(buf); |
5260325f | 413 | |
aa3378df | 414 | /* |
415 | * Check that the versions match. In future this might accept | |
416 | * several versions and set appropriate flags to handle them. | |
417 | */ | |
8ce64345 | 418 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", |
419 | &remote_major, &remote_minor, remote_version) != 3) | |
5260325f | 420 | fatal("Bad remote protocol version identification: '%.100s'", buf); |
421 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
184eed6a | 422 | remote_major, remote_minor, remote_version); |
5260325f | 423 | |
8ce64345 | 424 | compat_datafellows(remote_version); |
a8be9f80 | 425 | mismatch = 0; |
426 | ||
6aacefa7 | 427 | switch (remote_major) { |
a8be9f80 | 428 | case 1: |
429 | if (remote_minor == 99 && | |
430 | (options.protocol & SSH_PROTO_2) && | |
431 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
432 | enable_compat20(); | |
433 | break; | |
5260325f | 434 | } |
a8be9f80 | 435 | if (!(options.protocol & SSH_PROTO_1)) { |
436 | mismatch = 1; | |
437 | break; | |
438 | } | |
439 | if (remote_minor < 3) { | |
440 | fatal("Remote machine has too old SSH software version."); | |
fa08c86b | 441 | } else if (remote_minor == 3 || remote_minor == 4) { |
a8be9f80 | 442 | /* We speak 1.3, too. */ |
443 | enable_compat13(); | |
fa08c86b | 444 | minor1 = 3; |
a8be9f80 | 445 | if (options.forward_agent) { |
446 | log("Agent forwarding disabled for protocol 1.3"); | |
447 | options.forward_agent = 0; | |
448 | } | |
449 | } | |
450 | break; | |
451 | case 2: | |
452 | if (options.protocol & SSH_PROTO_2) { | |
453 | enable_compat20(); | |
454 | break; | |
455 | } | |
456 | /* FALLTHROUGH */ | |
6ae2364d | 457 | default: |
a8be9f80 | 458 | mismatch = 1; |
459 | break; | |
8efc0c15 | 460 | } |
a8be9f80 | 461 | if (mismatch) |
5260325f | 462 | fatal("Protocol major versions differ: %d vs. %d", |
a8be9f80 | 463 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
464 | remote_major); | |
5260325f | 465 | /* Send our own protocol version identification. */ |
466 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
a8be9f80 | 467 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
fa08c86b | 468 | compat20 ? PROTOCOL_MINOR_2 : minor1, |
8ce64345 | 469 | SSH_VERSION); |
a408af76 | 470 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) |
5260325f | 471 | fatal("write: %.100s", strerror(errno)); |
8ce64345 | 472 | client_version_string = xstrdup(buf); |
473 | chop(client_version_string); | |
474 | chop(server_version_string); | |
475 | debug("Local version string %.100s", client_version_string); | |
8efc0c15 | 476 | } |
477 | ||
f21032a6 | 478 | /* defaults to 'no' */ |
396c147e | 479 | static int |
a2c92c4a | 480 | confirm(const char *prompt) |
8efc0c15 | 481 | { |
616a6b93 | 482 | const char *msg, *again = "Please type 'yes' or 'no': "; |
483 | char *p; | |
484 | int ret = -1; | |
5260325f | 485 | |
f21032a6 | 486 | if (options.batch_mode) |
487 | return 0; | |
616a6b93 | 488 | for (msg = prompt;;msg = again) { |
489 | p = read_passphrase(msg, RP_ECHO); | |
490 | if (p == NULL || | |
491 | (p[0] == '\0') || (p[0] == '\n') || | |
492 | strncasecmp(p, "no", 2) == 0) | |
493 | ret = 0; | |
494 | if (strncasecmp(p, "yes", 3) == 0) | |
495 | ret = 1; | |
496 | if (p) | |
497 | xfree(p); | |
498 | if (ret != -1) | |
499 | return ret; | |
8efc0c15 | 500 | } |
8efc0c15 | 501 | } |
502 | ||
5260325f | 503 | /* |
f49bc4f7 | 504 | * check whether the supplied host key is valid, return -1 if the key |
505 | * is not valid. the user_hostfile will not be updated if 'readonly' is true. | |
5260325f | 506 | */ |
95f1eccc | 507 | |
396c147e | 508 | static int |
a306f2dd | 509 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, |
f49bc4f7 | 510 | int readonly, const char *user_hostfile, const char *system_hostfile) |
8efc0c15 | 511 | { |
4fe2af09 | 512 | Key *file_key; |
1d1ffb87 | 513 | char *type = key_type(host_key); |
95f1eccc | 514 | char *ip = NULL; |
22138a36 | 515 | char hostline[1000], *hostp, *fp; |
5260325f | 516 | HostStatus host_status; |
517 | HostStatus ip_status; | |
48e671d5 | 518 | int local = 0, host_ip_differ = 0; |
20af321f | 519 | int salen; |
48e671d5 | 520 | char ntop[NI_MAXHOST]; |
616a6b93 | 521 | char msg[1024]; |
522 | int len, host_line, ip_line; | |
1e3b8b07 | 523 | const char *host_file = NULL, *ip_file = NULL; |
48e671d5 | 524 | |
525 | /* | |
526 | * Force accepting of the host key for loopback/localhost. The | |
527 | * problem is that if the home directory is NFS-mounted to multiple | |
528 | * machines, localhost will refer to a different machine in each of | |
529 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
530 | * essentially disables host authentication for localhost; however, | |
531 | * this is probably not a real problem. | |
532 | */ | |
a306f2dd | 533 | /** hostaddr == 0! */ |
48e671d5 | 534 | switch (hostaddr->sa_family) { |
535 | case AF_INET: | |
f49bc4f7 | 536 | local = (ntohl(((struct sockaddr_in *)hostaddr)-> |
20a11d35 | 537 | sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; |
20af321f | 538 | salen = sizeof(struct sockaddr_in); |
48e671d5 | 539 | break; |
540 | case AF_INET6: | |
f49bc4f7 | 541 | local = IN6_IS_ADDR_LOOPBACK( |
542 | &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
20af321f | 543 | salen = sizeof(struct sockaddr_in6); |
48e671d5 | 544 | break; |
545 | default: | |
546 | local = 0; | |
20af321f | 547 | salen = sizeof(struct sockaddr_storage); |
48e671d5 | 548 | break; |
549 | } | |
8bbc048a | 550 | if (options.no_host_authentication_for_localhost == 1 && local && |
551 | options.host_key_alias == NULL) { | |
7c49df64 | 552 | debug("Forcing accepting of host key for " |
553 | "loopback/localhost."); | |
f49bc4f7 | 554 | return 0; |
48e671d5 | 555 | } |
5260325f | 556 | |
57112b5a | 557 | /* |
7c49df64 | 558 | * We don't have the remote ip-address for connections |
559 | * using a proxy command | |
560 | */ | |
561 | if (options.proxy_command == NULL) { | |
562 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), | |
563 | NULL, 0, NI_NUMERICHOST) != 0) | |
564 | fatal("check_host_key: getnameinfo failed"); | |
565 | ip = xstrdup(ntop); | |
566 | } else { | |
567 | ip = xstrdup("<no hostip for proxy command>"); | |
568 | } | |
569 | /* | |
570 | * Turn off check_host_ip if the connection is to localhost, via proxy | |
571 | * command or if we don't have a hostname to compare with | |
57112b5a | 572 | */ |
7c49df64 | 573 | if (options.check_host_ip && |
574 | (local || strcmp(host, ip) == 0 || options.proxy_command != NULL)) | |
57112b5a | 575 | options.check_host_ip = 0; |
576 | ||
8abcdba4 | 577 | /* |
7c49df64 | 578 | * Allow the user to record the key under a different name. This is |
8abcdba4 | 579 | * useful for ssh tunneling over forwarded connections or if you run |
7c49df64 | 580 | * multiple sshd's on different ports on the same machine. |
8abcdba4 | 581 | */ |
582 | if (options.host_key_alias != NULL) { | |
583 | host = options.host_key_alias; | |
584 | debug("using hostkeyalias: %s", host); | |
585 | } | |
586 | ||
95f1eccc | 587 | /* |
588 | * Store the host key from the known host file in here so that we can | |
589 | * compare it with the key for the IP address. | |
590 | */ | |
4fe2af09 | 591 | file_key = key_new(host_key->type); |
5260325f | 592 | |
aa3378df | 593 | /* |
594 | * Check if the host key is present in the user\'s list of known | |
595 | * hosts or in the systemwide list. | |
596 | */ | |
1e3b8b07 | 597 | host_file = user_hostfile; |
f49bc4f7 | 598 | host_status = check_host_in_hostfile(host_file, host, host_key, |
184eed6a | 599 | file_key, &host_line); |
1e3b8b07 | 600 | if (host_status == HOST_NEW) { |
601 | host_file = system_hostfile; | |
f49bc4f7 | 602 | host_status = check_host_in_hostfile(host_file, host, host_key, |
603 | file_key, &host_line); | |
1e3b8b07 | 604 | } |
aa3378df | 605 | /* |
606 | * Also perform check for the ip address, skip the check if we are | |
607 | * localhost or the hostname was an ip address to begin with | |
608 | */ | |
7c49df64 | 609 | if (options.check_host_ip) { |
4fe2af09 | 610 | Key *ip_key = key_new(host_key->type); |
5260325f | 611 | |
1e3b8b07 | 612 | ip_file = user_hostfile; |
f49bc4f7 | 613 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, |
614 | ip_key, &ip_line); | |
1e3b8b07 | 615 | if (ip_status == HOST_NEW) { |
616 | ip_file = system_hostfile; | |
f49bc4f7 | 617 | ip_status = check_host_in_hostfile(ip_file, ip, |
618 | host_key, ip_key, &ip_line); | |
1e3b8b07 | 619 | } |
5260325f | 620 | if (host_status == HOST_CHANGED && |
4fe2af09 | 621 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) |
5260325f | 622 | host_ip_differ = 1; |
623 | ||
4fe2af09 | 624 | key_free(ip_key); |
5260325f | 625 | } else |
626 | ip_status = host_status; | |
627 | ||
4fe2af09 | 628 | key_free(file_key); |
5260325f | 629 | |
630 | switch (host_status) { | |
631 | case HOST_OK: | |
632 | /* The host is known and the key matches. */ | |
1d1ffb87 | 633 | debug("Host '%.200s' is known and matches the %s host key.", |
634 | host, type); | |
1e3b8b07 | 635 | debug("Found key in %s:%d", host_file, host_line); |
7c49df64 | 636 | if (options.check_host_ip && ip_status == HOST_NEW) { |
f49bc4f7 | 637 | if (readonly) |
638 | log("%s host key for IP address " | |
639 | "'%.128s' not in list of known hosts.", | |
7c49df64 | 640 | type, ip); |
f49bc4f7 | 641 | else if (!add_host_to_hostfile(user_hostfile, ip, |
184eed6a | 642 | host_key)) |
f49bc4f7 | 643 | log("Failed to add the %s host key for IP " |
644 | "address '%.128s' to the list of known " | |
645 | "hosts (%.30s).", type, ip, user_hostfile); | |
646 | else | |
647 | log("Warning: Permanently added the %s host " | |
648 | "key for IP address '%.128s' to the list " | |
649 | "of known hosts.", type, ip); | |
5260325f | 650 | } |
651 | break; | |
652 | case HOST_NEW: | |
f49bc4f7 | 653 | if (readonly) |
654 | goto fail; | |
5260325f | 655 | /* The host is new. */ |
656 | if (options.strict_host_key_checking == 1) { | |
f49bc4f7 | 657 | /* |
658 | * User has requested strict host key checking. We | |
659 | * will not add the host key automatically. The only | |
660 | * alternative left is to abort. | |
661 | */ | |
662 | error("No %s host key is known for %.200s and you " | |
663 | "have requested strict checking.", type, host); | |
664 | goto fail; | |
5260325f | 665 | } else if (options.strict_host_key_checking == 2) { |
666 | /* The default */ | |
22138a36 | 667 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
616a6b93 | 668 | snprintf(msg, sizeof(msg), |
f49bc4f7 | 669 | "The authenticity of host '%.200s (%s)' can't be " |
670 | "established.\n" | |
1d1ffb87 | 671 | "%s key fingerprint is %s.\n" |
f49bc4f7 | 672 | "Are you sure you want to continue connecting " |
673 | "(yes/no)? ", host, ip, type, fp); | |
22138a36 | 674 | xfree(fp); |
616a6b93 | 675 | if (!confirm(msg)) |
f49bc4f7 | 676 | goto fail; |
5260325f | 677 | } |
7c49df64 | 678 | if (options.check_host_ip && ip_status == HOST_NEW) { |
5260325f | 679 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); |
680 | hostp = hostline; | |
681 | } else | |
682 | hostp = host; | |
683 | ||
f49bc4f7 | 684 | /* |
685 | * If not in strict mode, add the key automatically to the | |
686 | * local known_hosts file. | |
687 | */ | |
a306f2dd | 688 | if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) |
f49bc4f7 | 689 | log("Failed to add the host to the list of known " |
690 | "hosts (%.500s).", user_hostfile); | |
5260325f | 691 | else |
f49bc4f7 | 692 | log("Warning: Permanently added '%.200s' (%s) to the " |
693 | "list of known hosts.", hostp, type); | |
5260325f | 694 | break; |
695 | case HOST_CHANGED: | |
696 | if (options.check_host_ip && host_ip_differ) { | |
697 | char *msg; | |
698 | if (ip_status == HOST_NEW) | |
699 | msg = "is unknown"; | |
700 | else if (ip_status == HOST_OK) | |
701 | msg = "is unchanged"; | |
702 | else | |
703 | msg = "has a different value"; | |
704 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
705 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
706 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1d1ffb87 | 707 | error("The %s host key for %s has changed,", type, host); |
5260325f | 708 | error("and the key for the according IP address %s", ip); |
709 | error("%s. This could either mean that", msg); | |
710 | error("DNS SPOOFING is happening or the IP address for the host"); | |
1e3b8b07 | 711 | error("and its host key have changed at the same time."); |
7c49df64 | 712 | if (ip_status != HOST_NEW) |
1e3b8b07 | 713 | error("Offending key for IP in %s:%d", ip_file, ip_line); |
5260325f | 714 | } |
715 | /* The host key has changed. */ | |
22138a36 | 716 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
5260325f | 717 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
ae2f7af7 | 718 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); |
5260325f | 719 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
720 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
721 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
1d1ffb87 | 722 | error("It is also possible that the %s host key has just been changed.", type); |
8abcdba4 | 723 | error("The fingerprint for the %s key sent by the remote host is\n%s.", |
22138a36 | 724 | type, fp); |
5260325f | 725 | error("Please contact your system administrator."); |
726 | error("Add correct host key in %.100s to get rid of this message.", | |
8abcdba4 | 727 | user_hostfile); |
1e3b8b07 | 728 | error("Offending key in %s:%d", host_file, host_line); |
22138a36 | 729 | xfree(fp); |
5260325f | 730 | |
aa3378df | 731 | /* |
732 | * If strict host key checking is in use, the user will have | |
733 | * to edit the key manually and we can only abort. | |
734 | */ | |
f49bc4f7 | 735 | if (options.strict_host_key_checking) { |
736 | error("%s host key for %.200s has changed and you have " | |
737 | "requested strict checking.", type, host); | |
738 | goto fail; | |
739 | } | |
5260325f | 740 | |
aa3378df | 741 | /* |
742 | * If strict host key checking has not been requested, allow | |
743 | * the connection but without password authentication or | |
744 | * agent forwarding. | |
745 | */ | |
5260325f | 746 | if (options.password_authentication) { |
f49bc4f7 | 747 | error("Password authentication is disabled to avoid " |
748 | "man-in-the-middle attacks."); | |
5260325f | 749 | options.password_authentication = 0; |
750 | } | |
751 | if (options.forward_agent) { | |
f49bc4f7 | 752 | error("Agent forwarding is disabled to avoid " |
753 | "man-in-the-middle attacks."); | |
5260325f | 754 | options.forward_agent = 0; |
755 | } | |
0b6fbf03 | 756 | if (options.forward_x11) { |
f49bc4f7 | 757 | error("X11 forwarding is disabled to avoid " |
758 | "man-in-the-middle attacks."); | |
0b6fbf03 | 759 | options.forward_x11 = 0; |
760 | } | |
f49bc4f7 | 761 | if (options.num_local_forwards > 0 || |
762 | options.num_remote_forwards > 0) { | |
763 | error("Port forwarding is disabled to avoid " | |
764 | "man-in-the-middle attacks."); | |
765 | options.num_local_forwards = | |
184eed6a | 766 | options.num_remote_forwards = 0; |
0b6fbf03 | 767 | } |
aa3378df | 768 | /* |
769 | * XXX Should permit the user to change to use the new id. | |
770 | * This could be done by converting the host key to an | |
771 | * identifying sentence, tell that the host identifies itself | |
772 | * by that sentence, and ask the user if he/she whishes to | |
773 | * accept the authentication. | |
774 | */ | |
5260325f | 775 | break; |
776 | } | |
0b6fbf03 | 777 | |
7c49df64 | 778 | if (options.check_host_ip && host_status != HOST_CHANGED && |
779 | ip_status == HOST_CHANGED) { | |
616a6b93 | 780 | snprintf(msg, sizeof(msg), |
781 | "Warning: the %s host key for '%.200s' " | |
782 | "differs from the key for the IP address '%.128s'" | |
783 | "\nOffending key for IP in %s:%d", | |
784 | type, host, ip, ip_file, ip_line); | |
785 | if (host_status == HOST_OK) { | |
786 | len = strlen(msg); | |
787 | snprintf(msg + len, sizeof(msg) - len, | |
788 | "\nMatching host key in %s:%d", | |
789 | host_file, host_line); | |
790 | } | |
7c49df64 | 791 | if (options.strict_host_key_checking == 1) { |
616a6b93 | 792 | log(msg); |
f49bc4f7 | 793 | error("Exiting, you have requested strict checking."); |
794 | goto fail; | |
7c49df64 | 795 | } else if (options.strict_host_key_checking == 2) { |
616a6b93 | 796 | strlcat(msg, "\nAre you sure you want " |
797 | "to continue connecting (yes/no)? ", sizeof(msg)); | |
798 | if (!confirm(msg)) | |
f49bc4f7 | 799 | goto fail; |
616a6b93 | 800 | } else { |
801 | log(msg); | |
7c49df64 | 802 | } |
803 | } | |
804 | ||
0b6fbf03 | 805 | xfree(ip); |
f49bc4f7 | 806 | return 0; |
807 | ||
808 | fail: | |
809 | xfree(ip); | |
810 | return -1; | |
811 | } | |
812 | ||
813 | int | |
814 | verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) | |
815 | { | |
816 | struct stat st; | |
817 | ||
818 | /* return ok if the key can be found in an old keyfile */ | |
819 | if (stat(options.system_hostfile2, &st) == 0 || | |
820 | stat(options.user_hostfile2, &st) == 0) { | |
821 | if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1, | |
822 | options.user_hostfile2, options.system_hostfile2) == 0) | |
823 | return 0; | |
824 | } | |
825 | return check_host_key(host, hostaddr, host_key, /*readonly*/ 0, | |
826 | options.user_hostfile, options.system_hostfile); | |
95f1eccc | 827 | } |
828 | ||
8ce64345 | 829 | /* |
a306f2dd | 830 | * Starts a dialog with the server, and authenticates the current user on the |
831 | * server. This does not need any extra privileges. The basic connection | |
832 | * to the server must already have been established before this is called. | |
833 | * If login fails, this function prints an error and never returns. | |
834 | * This function does not require super-user privileges. | |
8ce64345 | 835 | */ |
836 | void | |
39c00dc2 | 837 | ssh_login(Sensitive *sensitive, const char *orighost, |
63bd8c36 | 838 | struct sockaddr *hostaddr, struct passwd *pw) |
8ce64345 | 839 | { |
a306f2dd | 840 | char *host, *cp; |
8ce64345 | 841 | char *server_user, *local_user; |
8ce64345 | 842 | |
8ce64345 | 843 | local_user = xstrdup(pw->pw_name); |
844 | server_user = options.user ? options.user : local_user; | |
845 | ||
7b2ea3a1 | 846 | /* Convert the user-supplied hostname into all lowercase. */ |
847 | host = xstrdup(orighost); | |
848 | for (cp = host; *cp; cp++) | |
849 | if (isupper(*cp)) | |
850 | *cp = tolower(*cp); | |
851 | ||
852 | /* Exchange protocol version identification strings with the server. */ | |
853 | ssh_exchange_identification(); | |
854 | ||
855 | /* Put the connection into non-blocking mode. */ | |
856 | packet_set_nonblocking(); | |
857 | ||
7b2ea3a1 | 858 | /* key exchange */ |
7b2ea3a1 | 859 | /* authenticate user */ |
8ce64345 | 860 | if (compat20) { |
861 | ssh_kex2(host, hostaddr); | |
39c00dc2 | 862 | ssh_userauth2(local_user, server_user, host, sensitive); |
8ce64345 | 863 | } else { |
8ce64345 | 864 | ssh_kex(host, hostaddr); |
39c00dc2 | 865 | ssh_userauth1(local_user, server_user, host, sensitive); |
8ce64345 | 866 | } |
7b2ea3a1 | 867 | } |
0ae4fe1d | 868 | |
869 | void | |
870 | ssh_put_password(char *password) | |
871 | { | |
872 | int size; | |
873 | char *padded; | |
874 | ||
99c415db | 875 | if (datafellows & SSH_BUG_PASSWORDPAD) { |
449c5ba5 | 876 | packet_put_cstring(password); |
99c415db | 877 | return; |
878 | } | |
0ae4fe1d | 879 | size = roundup(strlen(password) + 1, 32); |
880 | padded = xmalloc(size); | |
881 | memset(padded, 0, size); | |
882 | strlcpy(padded, password, size); | |
883 | packet_put_string(padded, size); | |
884 | memset(padded, 0, size); | |
885 | xfree(padded); | |
886 | } |