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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" | |
21289cd0 | 16 | RCSID("$OpenBSD: sshconnect.c,v 1.140 2003/05/14 18:16:21 jakob 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 | |
21289cd0 | 36 | #ifdef DNS |
37 | #include "dns.h" | |
38 | #endif | |
39 | ||
a306f2dd | 40 | char *client_version_string = NULL; |
41 | char *server_version_string = NULL; | |
8ce64345 | 42 | |
3fb156df | 43 | /* import */ |
57112b5a | 44 | extern Options options; |
48e671d5 | 45 | extern char *__progname; |
3fb156df | 46 | extern uid_t original_real_uid; |
47 | extern uid_t original_effective_uid; | |
6939bbd4 | 48 | extern pid_t proxy_command_pid; |
57112b5a | 49 | |
a704dd54 | 50 | #ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */ |
51 | #define INET6_ADDRSTRLEN 46 | |
52 | #endif | |
53 | ||
8a48a7ef | 54 | static int show_other_keys(const char *, Key *); |
55 | ||
5260325f | 56 | /* |
57 | * Connect to the given ssh server using a proxy command. | |
58 | */ | |
396c147e | 59 | static int |
3fb156df | 60 | ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) |
8efc0c15 | 61 | { |
5260325f | 62 | Buffer command; |
63 | const char *cp; | |
64 | char *command_string; | |
65 | int pin[2], pout[2]; | |
9da5c3c9 | 66 | pid_t pid; |
48e671d5 | 67 | char strport[NI_MAXSERV]; |
5260325f | 68 | |
69 | /* Convert the port number into a string. */ | |
48e671d5 | 70 | snprintf(strport, sizeof strport, "%hu", port); |
5260325f | 71 | |
6939bbd4 | 72 | /* |
73 | * Build the final command string in the buffer by making the | |
74 | * appropriate substitutions to the given proxy command. | |
75 | * | |
76 | * Use "exec" to avoid "sh -c" processes on some platforms | |
77 | * (e.g. Solaris) | |
78 | */ | |
5260325f | 79 | buffer_init(&command); |
6939bbd4 | 80 | buffer_append(&command, "exec ", 5); |
81 | ||
5260325f | 82 | for (cp = proxy_command; *cp; cp++) { |
83 | if (cp[0] == '%' && cp[1] == '%') { | |
84 | buffer_append(&command, "%", 1); | |
85 | cp++; | |
86 | continue; | |
87 | } | |
88 | if (cp[0] == '%' && cp[1] == 'h') { | |
89 | buffer_append(&command, host, strlen(host)); | |
90 | cp++; | |
91 | continue; | |
92 | } | |
93 | if (cp[0] == '%' && cp[1] == 'p') { | |
48e671d5 | 94 | buffer_append(&command, strport, strlen(strport)); |
5260325f | 95 | cp++; |
96 | continue; | |
97 | } | |
98 | buffer_append(&command, cp, 1); | |
8efc0c15 | 99 | } |
5260325f | 100 | buffer_append(&command, "\0", 1); |
101 | ||
102 | /* Get the final command string. */ | |
103 | command_string = buffer_ptr(&command); | |
104 | ||
105 | /* Create pipes for communicating with the proxy. */ | |
106 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
107 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
184eed6a | 108 | strerror(errno)); |
5260325f | 109 | |
110 | debug("Executing proxy command: %.500s", command_string); | |
111 | ||
112 | /* Fork and execute the proxy command. */ | |
113 | if ((pid = fork()) == 0) { | |
114 | char *argv[10]; | |
115 | ||
116 | /* Child. Permanently give up superuser privileges. */ | |
3fb156df | 117 | seteuid(original_real_uid); |
118 | setuid(original_real_uid); | |
5260325f | 119 | |
120 | /* Redirect stdin and stdout. */ | |
121 | close(pin[1]); | |
122 | if (pin[0] != 0) { | |
123 | if (dup2(pin[0], 0) < 0) | |
124 | perror("dup2 stdin"); | |
125 | close(pin[0]); | |
126 | } | |
127 | close(pout[0]); | |
128 | if (dup2(pout[1], 1) < 0) | |
129 | perror("dup2 stdout"); | |
130 | /* Cannot be 1 because pin allocated two descriptors. */ | |
131 | close(pout[1]); | |
132 | ||
133 | /* Stderr is left as it is so that error messages get | |
134 | printed on the user's terminal. */ | |
30228d7c | 135 | argv[0] = _PATH_BSHELL; |
5260325f | 136 | argv[1] = "-c"; |
137 | argv[2] = command_string; | |
138 | argv[3] = NULL; | |
139 | ||
140 | /* Execute the proxy command. Note that we gave up any | |
141 | extra privileges above. */ | |
328654d8 | 142 | execv(argv[0], argv); |
143 | perror(argv[0]); | |
5260325f | 144 | exit(1); |
8efc0c15 | 145 | } |
5260325f | 146 | /* Parent. */ |
147 | if (pid < 0) | |
148 | fatal("fork failed: %.100s", strerror(errno)); | |
6939bbd4 | 149 | else |
150 | proxy_command_pid = pid; /* save pid to clean up later */ | |
5260325f | 151 | |
152 | /* Close child side of the descriptors. */ | |
153 | close(pin[0]); | |
154 | close(pout[1]); | |
155 | ||
156 | /* Free the command name. */ | |
157 | buffer_free(&command); | |
158 | ||
159 | /* Set the connection file descriptors. */ | |
160 | packet_set_connection(pout[0], pin[1]); | |
8efc0c15 | 161 | |
ce773142 | 162 | /* Indicate OK return */ |
163 | return 0; | |
5260325f | 164 | } |
8efc0c15 | 165 | |
5260325f | 166 | /* |
167 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
168 | */ | |
396c147e | 169 | static int |
3e131a6d | 170 | ssh_create_socket(int privileged, struct addrinfo *ai) |
8efc0c15 | 171 | { |
3435f5a6 | 172 | int sock, gaierr; |
173 | struct addrinfo hints, *res; | |
5260325f | 174 | |
aa3378df | 175 | /* |
176 | * If we are running as root and want to connect to a privileged | |
177 | * port, bind our own socket to a privileged port. | |
178 | */ | |
5260325f | 179 | if (privileged) { |
180 | int p = IPPORT_RESERVED - 1; | |
3fb156df | 181 | PRIV_START; |
3e131a6d | 182 | sock = rresvport_af(&p, ai->ai_family); |
3fb156df | 183 | PRIV_END; |
5260325f | 184 | if (sock < 0) |
3e131a6d | 185 | error("rresvport: af=%d %.100s", ai->ai_family, |
186 | strerror(errno)); | |
c8d54615 | 187 | else |
188 | debug("Allocated local port %d.", p); | |
3435f5a6 | 189 | return sock; |
190 | } | |
3e131a6d | 191 | sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); |
3435f5a6 | 192 | if (sock < 0) |
193 | error("socket: %.100s", strerror(errno)); | |
3435f5a6 | 194 | |
195 | /* Bind the socket to an alternative local IP address */ | |
196 | if (options.bind_address == NULL) | |
197 | return sock; | |
198 | ||
199 | memset(&hints, 0, sizeof(hints)); | |
3e131a6d | 200 | hints.ai_family = ai->ai_family; |
201 | hints.ai_socktype = ai->ai_socktype; | |
202 | hints.ai_protocol = ai->ai_protocol; | |
3435f5a6 | 203 | hints.ai_flags = AI_PASSIVE; |
204 | gaierr = getaddrinfo(options.bind_address, "0", &hints, &res); | |
205 | if (gaierr) { | |
206 | error("getaddrinfo: %s: %s", options.bind_address, | |
207 | gai_strerror(gaierr)); | |
208 | close(sock); | |
209 | return -1; | |
210 | } | |
211 | if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { | |
212 | error("bind: %s: %s", options.bind_address, strerror(errno)); | |
213 | close(sock); | |
214 | freeaddrinfo(res); | |
215 | return -1; | |
5260325f | 216 | } |
3435f5a6 | 217 | freeaddrinfo(res); |
5260325f | 218 | return sock; |
8efc0c15 | 219 | } |
220 | ||
5260325f | 221 | /* |
48e671d5 | 222 | * Opens a TCP/IP connection to the remote server on the given host. |
223 | * The address of the remote host will be returned in hostaddr. | |
3fb156df | 224 | * If port is 0, the default port will be used. If needpriv is true, |
5260325f | 225 | * a privileged port will be allocated to make the connection. |
3fb156df | 226 | * This requires super-user privileges if needpriv is true. |
5260325f | 227 | * Connection_attempts specifies the maximum number of tries (one per |
228 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
229 | * and %p substituted for host and port, respectively) to use to contact | |
230 | * the daemon. | |
ce773142 | 231 | * Return values: |
232 | * 0 for OK | |
233 | * ECONNREFUSED if we got a "Connection Refused" by the peer on any address | |
234 | * ECONNABORTED if we failed without a "Connection refused" | |
235 | * Suitable error messages for the connection failure will already have been | |
236 | * printed. | |
5260325f | 237 | */ |
238 | int | |
48e671d5 | 239 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, |
dab89049 | 240 | u_short port, int family, int connection_attempts, |
3fb156df | 241 | int needpriv, const char *proxy_command) |
8efc0c15 | 242 | { |
b5c334cc | 243 | int gaierr; |
244 | int on = 1; | |
48e671d5 | 245 | int sock = -1, attempt; |
48e671d5 | 246 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; |
b5c334cc | 247 | struct addrinfo hints, *ai, *aitop; |
b5c334cc | 248 | struct servent *sp; |
ce773142 | 249 | /* |
250 | * Did we get only other errors than "Connection refused" (which | |
251 | * should block fallback to rsh and similar), or did we get at least | |
252 | * one "Connection refused"? | |
253 | */ | |
254 | int full_failure = 1; | |
5260325f | 255 | |
a77673cc | 256 | debug2("ssh_connect: needpriv %d", needpriv); |
5260325f | 257 | |
258 | /* Get default port if port has not been set. */ | |
259 | if (port == 0) { | |
260 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
261 | if (sp) | |
262 | port = ntohs(sp->s_port); | |
263 | else | |
264 | port = SSH_DEFAULT_PORT; | |
8efc0c15 | 265 | } |
5260325f | 266 | /* If a proxy command is given, connect using it. */ |
267 | if (proxy_command != NULL) | |
3fb156df | 268 | return ssh_proxy_connect(host, port, proxy_command); |
5260325f | 269 | |
270 | /* No proxy command. */ | |
271 | ||
48e671d5 | 272 | memset(&hints, 0, sizeof(hints)); |
dab89049 | 273 | hints.ai_family = family; |
48e671d5 | 274 | hints.ai_socktype = SOCK_STREAM; |
d6133f43 | 275 | snprintf(strport, sizeof strport, "%u", port); |
48e671d5 | 276 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) |
277 | fatal("%s: %.100s: %s", __progname, host, | |
278 | gai_strerror(gaierr)); | |
5260325f | 279 | |
95f1eccc | 280 | /* |
281 | * Try to connect several times. On some machines, the first time | |
282 | * will sometimes fail. In general socket code appears to behave | |
283 | * quite magically on many machines. | |
ce773142 | 284 | */ |
285 | for (attempt = 0; ;) { | |
5260325f | 286 | if (attempt > 0) |
287 | debug("Trying again..."); | |
288 | ||
48e671d5 | 289 | /* Loop through addresses for this host, and try each one in |
6ae2364d | 290 | sequence until the connection succeeds. */ |
48e671d5 | 291 | for (ai = aitop; ai; ai = ai->ai_next) { |
292 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
293 | continue; | |
294 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
295 | ntop, sizeof(ntop), strport, sizeof(strport), | |
296 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
297 | error("ssh_connect: getnameinfo failed"); | |
298 | continue; | |
299 | } | |
300 | debug("Connecting to %.200s [%.100s] port %s.", | |
301 | host, ntop, strport); | |
302 | ||
303 | /* Create a socket for connecting. */ | |
3e131a6d | 304 | sock = ssh_create_socket(needpriv, ai); |
48e671d5 | 305 | if (sock < 0) |
ce773142 | 306 | /* Any error is already output */ |
48e671d5 | 307 | continue; |
308 | ||
48e671d5 | 309 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { |
310 | /* Successful connection. */ | |
cd332296 | 311 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); |
5260325f | 312 | break; |
48e671d5 | 313 | } else { |
ce773142 | 314 | if (errno == ECONNREFUSED) |
315 | full_failure = 0; | |
c750d869 | 316 | debug("connect to address %s port %s: %s", |
317 | ntop, strport, strerror(errno)); | |
aa3378df | 318 | /* |
319 | * Close the failed socket; there appear to | |
320 | * be some problems when reusing a socket for | |
321 | * which connect() has already returned an | |
322 | * error. | |
323 | */ | |
5260325f | 324 | close(sock); |
325 | } | |
8efc0c15 | 326 | } |
48e671d5 | 327 | if (ai) |
328 | break; /* Successful connection. */ | |
8efc0c15 | 329 | |
ce773142 | 330 | attempt++; |
331 | if (attempt >= connection_attempts) | |
332 | break; | |
5260325f | 333 | /* Sleep a moment before retrying. */ |
334 | sleep(1); | |
335 | } | |
48e671d5 | 336 | |
337 | freeaddrinfo(aitop); | |
338 | ||
5260325f | 339 | /* Return failure if we didn't get a successful connection. */ |
9bd68577 | 340 | if (attempt >= connection_attempts) { |
bbe88b6d | 341 | logit("ssh: connect to host %s port %s: %s", |
9bd68577 | 342 | host, strport, strerror(errno)); |
ce773142 | 343 | return full_failure ? ECONNABORTED : ECONNREFUSED; |
9bd68577 | 344 | } |
8efc0c15 | 345 | |
5260325f | 346 | debug("Connection established."); |
8efc0c15 | 347 | |
b5c334cc | 348 | /* Set keepalives if requested. */ |
349 | if (options.keepalives && | |
350 | setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, | |
351 | sizeof(on)) < 0) | |
352 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
8efc0c15 | 353 | |
5260325f | 354 | /* Set the connection. */ |
355 | packet_set_connection(sock, sock); | |
8efc0c15 | 356 | |
ce773142 | 357 | return 0; |
8efc0c15 | 358 | } |
359 | ||
5260325f | 360 | /* |
361 | * Waits for the server identification string, and sends our own | |
362 | * identification string. | |
363 | */ | |
396c147e | 364 | static void |
5ca51e19 | 365 | ssh_exchange_identification(void) |
8efc0c15 | 366 | { |
5260325f | 367 | char buf[256], remote_version[256]; /* must be same size! */ |
a8be9f80 | 368 | int remote_major, remote_minor, i, mismatch; |
5260325f | 369 | int connection_in = packet_get_connection_in(); |
370 | int connection_out = packet_get_connection_out(); | |
2b87da3b | 371 | int minor1 = PROTOCOL_MINOR_1; |
5260325f | 372 | |
373 | /* Read other side\'s version identification. */ | |
38c295d6 | 374 | for (;;) { |
375 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
376 | int len = atomicio(read, connection_in, &buf[i], 1); | |
377 | if (len < 0) | |
378 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); | |
379 | if (len != 1) | |
380 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
381 | if (buf[i] == '\r') { | |
382 | buf[i] = '\n'; | |
383 | buf[i + 1] = 0; | |
384 | continue; /**XXX wait for \n */ | |
385 | } | |
386 | if (buf[i] == '\n') { | |
387 | buf[i + 1] = 0; | |
388 | break; | |
389 | } | |
5260325f | 390 | } |
38c295d6 | 391 | buf[sizeof(buf) - 1] = 0; |
392 | if (strncmp(buf, "SSH-", 4) == 0) | |
5260325f | 393 | break; |
38c295d6 | 394 | debug("ssh_exchange_identification: %s", buf); |
8efc0c15 | 395 | } |
8ce64345 | 396 | server_version_string = xstrdup(buf); |
5260325f | 397 | |
aa3378df | 398 | /* |
399 | * Check that the versions match. In future this might accept | |
400 | * several versions and set appropriate flags to handle them. | |
401 | */ | |
8ce64345 | 402 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", |
403 | &remote_major, &remote_minor, remote_version) != 3) | |
5260325f | 404 | fatal("Bad remote protocol version identification: '%.100s'", buf); |
405 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
184eed6a | 406 | remote_major, remote_minor, remote_version); |
5260325f | 407 | |
8ce64345 | 408 | compat_datafellows(remote_version); |
a8be9f80 | 409 | mismatch = 0; |
410 | ||
6aacefa7 | 411 | switch (remote_major) { |
a8be9f80 | 412 | case 1: |
413 | if (remote_minor == 99 && | |
414 | (options.protocol & SSH_PROTO_2) && | |
415 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
416 | enable_compat20(); | |
417 | break; | |
5260325f | 418 | } |
a8be9f80 | 419 | if (!(options.protocol & SSH_PROTO_1)) { |
420 | mismatch = 1; | |
421 | break; | |
422 | } | |
423 | if (remote_minor < 3) { | |
424 | fatal("Remote machine has too old SSH software version."); | |
fa08c86b | 425 | } else if (remote_minor == 3 || remote_minor == 4) { |
a8be9f80 | 426 | /* We speak 1.3, too. */ |
427 | enable_compat13(); | |
fa08c86b | 428 | minor1 = 3; |
a8be9f80 | 429 | if (options.forward_agent) { |
bbe88b6d | 430 | logit("Agent forwarding disabled for protocol 1.3"); |
a8be9f80 | 431 | options.forward_agent = 0; |
432 | } | |
433 | } | |
434 | break; | |
435 | case 2: | |
436 | if (options.protocol & SSH_PROTO_2) { | |
437 | enable_compat20(); | |
438 | break; | |
439 | } | |
440 | /* FALLTHROUGH */ | |
6ae2364d | 441 | default: |
a8be9f80 | 442 | mismatch = 1; |
443 | break; | |
8efc0c15 | 444 | } |
a8be9f80 | 445 | if (mismatch) |
5260325f | 446 | fatal("Protocol major versions differ: %d vs. %d", |
a8be9f80 | 447 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
448 | remote_major); | |
5260325f | 449 | /* Send our own protocol version identification. */ |
450 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
a8be9f80 | 451 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
fa08c86b | 452 | compat20 ? PROTOCOL_MINOR_2 : minor1, |
8ce64345 | 453 | SSH_VERSION); |
a408af76 | 454 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) |
5260325f | 455 | fatal("write: %.100s", strerror(errno)); |
8ce64345 | 456 | client_version_string = xstrdup(buf); |
457 | chop(client_version_string); | |
458 | chop(server_version_string); | |
459 | debug("Local version string %.100s", client_version_string); | |
8efc0c15 | 460 | } |
461 | ||
f21032a6 | 462 | /* defaults to 'no' */ |
396c147e | 463 | static int |
a2c92c4a | 464 | confirm(const char *prompt) |
8efc0c15 | 465 | { |
616a6b93 | 466 | const char *msg, *again = "Please type 'yes' or 'no': "; |
467 | char *p; | |
468 | int ret = -1; | |
5260325f | 469 | |
f21032a6 | 470 | if (options.batch_mode) |
471 | return 0; | |
616a6b93 | 472 | for (msg = prompt;;msg = again) { |
473 | p = read_passphrase(msg, RP_ECHO); | |
474 | if (p == NULL || | |
475 | (p[0] == '\0') || (p[0] == '\n') || | |
476 | strncasecmp(p, "no", 2) == 0) | |
477 | ret = 0; | |
f11fe301 | 478 | if (p && strncasecmp(p, "yes", 3) == 0) |
616a6b93 | 479 | ret = 1; |
480 | if (p) | |
481 | xfree(p); | |
482 | if (ret != -1) | |
483 | return ret; | |
8efc0c15 | 484 | } |
8efc0c15 | 485 | } |
486 | ||
5260325f | 487 | /* |
f49bc4f7 | 488 | * check whether the supplied host key is valid, return -1 if the key |
489 | * is not valid. the user_hostfile will not be updated if 'readonly' is true. | |
5260325f | 490 | */ |
396c147e | 491 | static int |
a306f2dd | 492 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, |
f49bc4f7 | 493 | int readonly, const char *user_hostfile, const char *system_hostfile) |
8efc0c15 | 494 | { |
4fe2af09 | 495 | Key *file_key; |
1d1ffb87 | 496 | char *type = key_type(host_key); |
95f1eccc | 497 | char *ip = NULL; |
22138a36 | 498 | char hostline[1000], *hostp, *fp; |
5260325f | 499 | HostStatus host_status; |
500 | HostStatus ip_status; | |
48e671d5 | 501 | int local = 0, host_ip_differ = 0; |
20af321f | 502 | int salen; |
48e671d5 | 503 | char ntop[NI_MAXHOST]; |
616a6b93 | 504 | char msg[1024]; |
8a48a7ef | 505 | int len, host_line, ip_line, has_keys; |
1e3b8b07 | 506 | const char *host_file = NULL, *ip_file = NULL; |
48e671d5 | 507 | |
508 | /* | |
509 | * Force accepting of the host key for loopback/localhost. The | |
510 | * problem is that if the home directory is NFS-mounted to multiple | |
511 | * machines, localhost will refer to a different machine in each of | |
512 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
513 | * essentially disables host authentication for localhost; however, | |
514 | * this is probably not a real problem. | |
515 | */ | |
a306f2dd | 516 | /** hostaddr == 0! */ |
48e671d5 | 517 | switch (hostaddr->sa_family) { |
518 | case AF_INET: | |
f49bc4f7 | 519 | local = (ntohl(((struct sockaddr_in *)hostaddr)-> |
20a11d35 | 520 | sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; |
20af321f | 521 | salen = sizeof(struct sockaddr_in); |
48e671d5 | 522 | break; |
523 | case AF_INET6: | |
f49bc4f7 | 524 | local = IN6_IS_ADDR_LOOPBACK( |
525 | &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
20af321f | 526 | salen = sizeof(struct sockaddr_in6); |
48e671d5 | 527 | break; |
528 | default: | |
529 | local = 0; | |
20af321f | 530 | salen = sizeof(struct sockaddr_storage); |
48e671d5 | 531 | break; |
532 | } | |
8bbc048a | 533 | if (options.no_host_authentication_for_localhost == 1 && local && |
534 | options.host_key_alias == NULL) { | |
7c49df64 | 535 | debug("Forcing accepting of host key for " |
536 | "loopback/localhost."); | |
f49bc4f7 | 537 | return 0; |
48e671d5 | 538 | } |
5260325f | 539 | |
57112b5a | 540 | /* |
7c49df64 | 541 | * We don't have the remote ip-address for connections |
542 | * using a proxy command | |
543 | */ | |
544 | if (options.proxy_command == NULL) { | |
545 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), | |
546 | NULL, 0, NI_NUMERICHOST) != 0) | |
547 | fatal("check_host_key: getnameinfo failed"); | |
548 | ip = xstrdup(ntop); | |
549 | } else { | |
550 | ip = xstrdup("<no hostip for proxy command>"); | |
551 | } | |
552 | /* | |
553 | * Turn off check_host_ip if the connection is to localhost, via proxy | |
554 | * command or if we don't have a hostname to compare with | |
57112b5a | 555 | */ |
7c49df64 | 556 | if (options.check_host_ip && |
557 | (local || strcmp(host, ip) == 0 || options.proxy_command != NULL)) | |
57112b5a | 558 | options.check_host_ip = 0; |
559 | ||
8abcdba4 | 560 | /* |
7c49df64 | 561 | * Allow the user to record the key under a different name. This is |
8abcdba4 | 562 | * useful for ssh tunneling over forwarded connections or if you run |
7c49df64 | 563 | * multiple sshd's on different ports on the same machine. |
8abcdba4 | 564 | */ |
565 | if (options.host_key_alias != NULL) { | |
566 | host = options.host_key_alias; | |
567 | debug("using hostkeyalias: %s", host); | |
568 | } | |
569 | ||
95f1eccc | 570 | /* |
571 | * Store the host key from the known host file in here so that we can | |
572 | * compare it with the key for the IP address. | |
573 | */ | |
4fe2af09 | 574 | file_key = key_new(host_key->type); |
5260325f | 575 | |
aa3378df | 576 | /* |
577 | * Check if the host key is present in the user\'s list of known | |
578 | * hosts or in the systemwide list. | |
579 | */ | |
1e3b8b07 | 580 | host_file = user_hostfile; |
f49bc4f7 | 581 | host_status = check_host_in_hostfile(host_file, host, host_key, |
184eed6a | 582 | file_key, &host_line); |
1e3b8b07 | 583 | if (host_status == HOST_NEW) { |
584 | host_file = system_hostfile; | |
f49bc4f7 | 585 | host_status = check_host_in_hostfile(host_file, host, host_key, |
586 | file_key, &host_line); | |
1e3b8b07 | 587 | } |
aa3378df | 588 | /* |
589 | * Also perform check for the ip address, skip the check if we are | |
590 | * localhost or the hostname was an ip address to begin with | |
591 | */ | |
7c49df64 | 592 | if (options.check_host_ip) { |
4fe2af09 | 593 | Key *ip_key = key_new(host_key->type); |
5260325f | 594 | |
1e3b8b07 | 595 | ip_file = user_hostfile; |
f49bc4f7 | 596 | ip_status = check_host_in_hostfile(ip_file, ip, host_key, |
597 | ip_key, &ip_line); | |
1e3b8b07 | 598 | if (ip_status == HOST_NEW) { |
599 | ip_file = system_hostfile; | |
f49bc4f7 | 600 | ip_status = check_host_in_hostfile(ip_file, ip, |
601 | host_key, ip_key, &ip_line); | |
1e3b8b07 | 602 | } |
5260325f | 603 | if (host_status == HOST_CHANGED && |
4fe2af09 | 604 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) |
5260325f | 605 | host_ip_differ = 1; |
606 | ||
4fe2af09 | 607 | key_free(ip_key); |
5260325f | 608 | } else |
609 | ip_status = host_status; | |
610 | ||
4fe2af09 | 611 | key_free(file_key); |
5260325f | 612 | |
613 | switch (host_status) { | |
614 | case HOST_OK: | |
615 | /* The host is known and the key matches. */ | |
1d1ffb87 | 616 | debug("Host '%.200s' is known and matches the %s host key.", |
617 | host, type); | |
1e3b8b07 | 618 | debug("Found key in %s:%d", host_file, host_line); |
7c49df64 | 619 | if (options.check_host_ip && ip_status == HOST_NEW) { |
f49bc4f7 | 620 | if (readonly) |
bbe88b6d | 621 | logit("%s host key for IP address " |
f49bc4f7 | 622 | "'%.128s' not in list of known hosts.", |
7c49df64 | 623 | type, ip); |
f49bc4f7 | 624 | else if (!add_host_to_hostfile(user_hostfile, ip, |
184eed6a | 625 | host_key)) |
bbe88b6d | 626 | logit("Failed to add the %s host key for IP " |
f49bc4f7 | 627 | "address '%.128s' to the list of known " |
628 | "hosts (%.30s).", type, ip, user_hostfile); | |
629 | else | |
bbe88b6d | 630 | logit("Warning: Permanently added the %s host " |
f49bc4f7 | 631 | "key for IP address '%.128s' to the list " |
632 | "of known hosts.", type, ip); | |
5260325f | 633 | } |
634 | break; | |
635 | case HOST_NEW: | |
f49bc4f7 | 636 | if (readonly) |
637 | goto fail; | |
5260325f | 638 | /* The host is new. */ |
639 | if (options.strict_host_key_checking == 1) { | |
f49bc4f7 | 640 | /* |
641 | * User has requested strict host key checking. We | |
642 | * will not add the host key automatically. The only | |
643 | * alternative left is to abort. | |
644 | */ | |
645 | error("No %s host key is known for %.200s and you " | |
646 | "have requested strict checking.", type, host); | |
647 | goto fail; | |
5260325f | 648 | } else if (options.strict_host_key_checking == 2) { |
8a48a7ef | 649 | has_keys = show_other_keys(host, host_key); |
5260325f | 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 " |
8a48a7ef | 654 | "established%s\n" |
1d1ffb87 | 655 | "%s key fingerprint is %s.\n" |
f49bc4f7 | 656 | "Are you sure you want to continue connecting " |
8a48a7ef | 657 | "(yes/no)? ", |
b77a87e5 | 658 | host, ip, |
659 | has_keys ? ",\nbut keys of different type are already " | |
660 | "known for this host." : ".", | |
661 | type, fp); | |
22138a36 | 662 | xfree(fp); |
616a6b93 | 663 | if (!confirm(msg)) |
f49bc4f7 | 664 | goto fail; |
5260325f | 665 | } |
7c49df64 | 666 | if (options.check_host_ip && ip_status == HOST_NEW) { |
5260325f | 667 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); |
668 | hostp = hostline; | |
669 | } else | |
670 | hostp = host; | |
671 | ||
f49bc4f7 | 672 | /* |
673 | * If not in strict mode, add the key automatically to the | |
674 | * local known_hosts file. | |
675 | */ | |
a306f2dd | 676 | if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) |
bbe88b6d | 677 | logit("Failed to add the host to the list of known " |
f49bc4f7 | 678 | "hosts (%.500s).", user_hostfile); |
5260325f | 679 | else |
bbe88b6d | 680 | logit("Warning: Permanently added '%.200s' (%s) to the " |
f49bc4f7 | 681 | "list of known hosts.", hostp, type); |
5260325f | 682 | break; |
683 | case HOST_CHANGED: | |
684 | if (options.check_host_ip && host_ip_differ) { | |
685 | char *msg; | |
686 | if (ip_status == HOST_NEW) | |
687 | msg = "is unknown"; | |
688 | else if (ip_status == HOST_OK) | |
689 | msg = "is unchanged"; | |
690 | else | |
691 | msg = "has a different value"; | |
692 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
693 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
694 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1d1ffb87 | 695 | error("The %s host key for %s has changed,", type, host); |
5260325f | 696 | error("and the key for the according IP address %s", ip); |
697 | error("%s. This could either mean that", msg); | |
698 | error("DNS SPOOFING is happening or the IP address for the host"); | |
1e3b8b07 | 699 | error("and its host key have changed at the same time."); |
7c49df64 | 700 | if (ip_status != HOST_NEW) |
1e3b8b07 | 701 | error("Offending key for IP in %s:%d", ip_file, ip_line); |
5260325f | 702 | } |
703 | /* The host key has changed. */ | |
22138a36 | 704 | fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); |
5260325f | 705 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
ae2f7af7 | 706 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); |
5260325f | 707 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
708 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
709 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
1d1ffb87 | 710 | error("It is also possible that the %s host key has just been changed.", type); |
8abcdba4 | 711 | error("The fingerprint for the %s key sent by the remote host is\n%s.", |
22138a36 | 712 | type, fp); |
5260325f | 713 | error("Please contact your system administrator."); |
714 | error("Add correct host key in %.100s to get rid of this message.", | |
8abcdba4 | 715 | user_hostfile); |
1e3b8b07 | 716 | error("Offending key in %s:%d", host_file, host_line); |
22138a36 | 717 | xfree(fp); |
5260325f | 718 | |
aa3378df | 719 | /* |
720 | * If strict host key checking is in use, the user will have | |
721 | * to edit the key manually and we can only abort. | |
722 | */ | |
f49bc4f7 | 723 | if (options.strict_host_key_checking) { |
724 | error("%s host key for %.200s has changed and you have " | |
725 | "requested strict checking.", type, host); | |
726 | goto fail; | |
727 | } | |
5260325f | 728 | |
aa3378df | 729 | /* |
730 | * If strict host key checking has not been requested, allow | |
731 | * the connection but without password authentication or | |
732 | * agent forwarding. | |
733 | */ | |
5260325f | 734 | if (options.password_authentication) { |
f49bc4f7 | 735 | error("Password authentication is disabled to avoid " |
736 | "man-in-the-middle attacks."); | |
5260325f | 737 | options.password_authentication = 0; |
738 | } | |
739 | if (options.forward_agent) { | |
f49bc4f7 | 740 | error("Agent forwarding is disabled to avoid " |
741 | "man-in-the-middle attacks."); | |
5260325f | 742 | options.forward_agent = 0; |
743 | } | |
0b6fbf03 | 744 | if (options.forward_x11) { |
f49bc4f7 | 745 | error("X11 forwarding is disabled to avoid " |
746 | "man-in-the-middle attacks."); | |
0b6fbf03 | 747 | options.forward_x11 = 0; |
748 | } | |
f49bc4f7 | 749 | if (options.num_local_forwards > 0 || |
750 | options.num_remote_forwards > 0) { | |
751 | error("Port forwarding is disabled to avoid " | |
752 | "man-in-the-middle attacks."); | |
753 | options.num_local_forwards = | |
184eed6a | 754 | options.num_remote_forwards = 0; |
0b6fbf03 | 755 | } |
aa3378df | 756 | /* |
757 | * XXX Should permit the user to change to use the new id. | |
758 | * This could be done by converting the host key to an | |
759 | * identifying sentence, tell that the host identifies itself | |
760 | * by that sentence, and ask the user if he/she whishes to | |
761 | * accept the authentication. | |
762 | */ | |
5260325f | 763 | break; |
8a48a7ef | 764 | case HOST_FOUND: |
765 | fatal("internal error"); | |
766 | break; | |
5260325f | 767 | } |
0b6fbf03 | 768 | |
7c49df64 | 769 | if (options.check_host_ip && host_status != HOST_CHANGED && |
770 | ip_status == HOST_CHANGED) { | |
616a6b93 | 771 | snprintf(msg, sizeof(msg), |
772 | "Warning: the %s host key for '%.200s' " | |
773 | "differs from the key for the IP address '%.128s'" | |
774 | "\nOffending key for IP in %s:%d", | |
775 | type, host, ip, ip_file, ip_line); | |
776 | if (host_status == HOST_OK) { | |
777 | len = strlen(msg); | |
778 | snprintf(msg + len, sizeof(msg) - len, | |
779 | "\nMatching host key in %s:%d", | |
7203d6bb | 780 | host_file, host_line); |
616a6b93 | 781 | } |
7c49df64 | 782 | if (options.strict_host_key_checking == 1) { |
bbe88b6d | 783 | logit(msg); |
f49bc4f7 | 784 | error("Exiting, you have requested strict checking."); |
785 | goto fail; | |
7c49df64 | 786 | } else if (options.strict_host_key_checking == 2) { |
616a6b93 | 787 | strlcat(msg, "\nAre you sure you want " |
788 | "to continue connecting (yes/no)? ", sizeof(msg)); | |
789 | if (!confirm(msg)) | |
f49bc4f7 | 790 | goto fail; |
616a6b93 | 791 | } else { |
bbe88b6d | 792 | logit(msg); |
7c49df64 | 793 | } |
794 | } | |
795 | ||
0b6fbf03 | 796 | xfree(ip); |
f49bc4f7 | 797 | return 0; |
798 | ||
799 | fail: | |
800 | xfree(ip); | |
801 | return -1; | |
802 | } | |
803 | ||
21289cd0 | 804 | /* returns 0 if key verifies or -1 if key does NOT verify */ |
f49bc4f7 | 805 | int |
806 | verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) | |
807 | { | |
808 | struct stat st; | |
809 | ||
21289cd0 | 810 | #ifdef DNS |
811 | if (options.verify_host_key_dns) { | |
812 | switch(verify_host_key_dns(host, hostaddr, host_key)) { | |
813 | case DNS_VERIFY_OK: | |
814 | return 0; | |
815 | case DNS_VERIFY_FAILED: | |
816 | return -1; | |
817 | case DNS_VERIFY_ERROR: | |
818 | break; | |
819 | default: | |
820 | debug3("bad return value from verify_host_key_dns"); | |
821 | break; | |
822 | } | |
823 | } | |
824 | #endif /* DNS */ | |
825 | ||
f49bc4f7 | 826 | /* return ok if the key can be found in an old keyfile */ |
827 | if (stat(options.system_hostfile2, &st) == 0 || | |
828 | stat(options.user_hostfile2, &st) == 0) { | |
829 | if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1, | |
830 | options.user_hostfile2, options.system_hostfile2) == 0) | |
831 | return 0; | |
832 | } | |
833 | return check_host_key(host, hostaddr, host_key, /*readonly*/ 0, | |
834 | options.user_hostfile, options.system_hostfile); | |
95f1eccc | 835 | } |
836 | ||
8ce64345 | 837 | /* |
a306f2dd | 838 | * Starts a dialog with the server, and authenticates the current user on the |
839 | * server. This does not need any extra privileges. The basic connection | |
840 | * to the server must already have been established before this is called. | |
841 | * If login fails, this function prints an error and never returns. | |
842 | * This function does not require super-user privileges. | |
8ce64345 | 843 | */ |
844 | void | |
39c00dc2 | 845 | ssh_login(Sensitive *sensitive, const char *orighost, |
63bd8c36 | 846 | struct sockaddr *hostaddr, struct passwd *pw) |
8ce64345 | 847 | { |
a306f2dd | 848 | char *host, *cp; |
8ce64345 | 849 | char *server_user, *local_user; |
8ce64345 | 850 | |
8ce64345 | 851 | local_user = xstrdup(pw->pw_name); |
852 | server_user = options.user ? options.user : local_user; | |
853 | ||
7b2ea3a1 | 854 | /* Convert the user-supplied hostname into all lowercase. */ |
855 | host = xstrdup(orighost); | |
856 | for (cp = host; *cp; cp++) | |
857 | if (isupper(*cp)) | |
858 | *cp = tolower(*cp); | |
859 | ||
860 | /* Exchange protocol version identification strings with the server. */ | |
861 | ssh_exchange_identification(); | |
862 | ||
863 | /* Put the connection into non-blocking mode. */ | |
864 | packet_set_nonblocking(); | |
865 | ||
7b2ea3a1 | 866 | /* key exchange */ |
7b2ea3a1 | 867 | /* authenticate user */ |
8ce64345 | 868 | if (compat20) { |
869 | ssh_kex2(host, hostaddr); | |
39c00dc2 | 870 | ssh_userauth2(local_user, server_user, host, sensitive); |
8ce64345 | 871 | } else { |
8ce64345 | 872 | ssh_kex(host, hostaddr); |
39c00dc2 | 873 | ssh_userauth1(local_user, server_user, host, sensitive); |
8ce64345 | 874 | } |
7b2ea3a1 | 875 | } |
0ae4fe1d | 876 | |
877 | void | |
878 | ssh_put_password(char *password) | |
879 | { | |
880 | int size; | |
881 | char *padded; | |
882 | ||
99c415db | 883 | if (datafellows & SSH_BUG_PASSWORDPAD) { |
449c5ba5 | 884 | packet_put_cstring(password); |
99c415db | 885 | return; |
886 | } | |
0ae4fe1d | 887 | size = roundup(strlen(password) + 1, 32); |
888 | padded = xmalloc(size); | |
889 | memset(padded, 0, size); | |
890 | strlcpy(padded, password, size); | |
891 | packet_put_string(padded, size); | |
892 | memset(padded, 0, size); | |
893 | xfree(padded); | |
894 | } | |
8a48a7ef | 895 | |
896 | static int | |
897 | show_key_from_file(const char *file, const char *host, int keytype) | |
898 | { | |
899 | Key *found; | |
900 | char *fp; | |
901 | int line, ret; | |
902 | ||
903 | found = key_new(keytype); | |
904 | if ((ret = lookup_key_in_hostfile_by_type(file, host, | |
905 | keytype, found, &line))) { | |
906 | fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX); | |
bbe88b6d | 907 | logit("WARNING: %s key found for host %s\n" |
567a05bf | 908 | "in %s:%d\n" |
8a48a7ef | 909 | "%s key fingerprint %s.", |
910 | key_type(found), host, file, line, | |
911 | key_type(found), fp); | |
912 | xfree(fp); | |
913 | } | |
914 | key_free(found); | |
915 | return (ret); | |
916 | } | |
917 | ||
918 | /* print all known host keys for a given host, but skip keys of given type */ | |
919 | static int | |
920 | show_other_keys(const char *host, Key *key) | |
921 | { | |
922 | int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1}; | |
923 | int i, found = 0; | |
924 | ||
925 | for (i = 0; type[i] != -1; i++) { | |
926 | if (type[i] == key->type) | |
927 | continue; | |
928 | if (type[i] != KEY_RSA1 && | |
929 | show_key_from_file(options.user_hostfile2, host, type[i])) { | |
930 | found = 1; | |
931 | continue; | |
932 | } | |
933 | if (type[i] != KEY_RSA1 && | |
934 | show_key_from_file(options.system_hostfile2, host, type[i])) { | |
935 | found = 1; | |
936 | continue; | |
937 | } | |
938 | if (show_key_from_file(options.user_hostfile, host, type[i])) { | |
939 | found = 1; | |
940 | continue; | |
941 | } | |
942 | if (show_key_from_file(options.system_hostfile, host, type[i])) { | |
943 | found = 1; | |
944 | continue; | |
945 | } | |
946 | debug2("no key of type %d for host %s", type[i], host); | |
947 | } | |
948 | return (found); | |
949 | } |