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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 | |
5 | * Created: Sat Mar 18 22:15:47 1995 ylo | |
6 | * Code to connect to a remote host, and to perform the client side of the | |
7 | * login (authentication) dialog. | |
8 | */ | |
8efc0c15 | 9 | |
10 | #include "includes.h" | |
301e9b01 | 11 | RCSID("$OpenBSD: sshconnect.c,v 1.74 2000/05/17 16:57:02 markus Exp $"); |
8efc0c15 | 12 | |
8ce64345 | 13 | #include <openssl/bn.h> |
a306f2dd | 14 | #include <openssl/dsa.h> |
15 | #include <openssl/rsa.h> | |
16 | ||
8efc0c15 | 17 | #include "xmalloc.h" |
18 | #include "rsa.h" | |
19 | #include "ssh.h" | |
8ce64345 | 20 | #include "buffer.h" |
8efc0c15 | 21 | #include "packet.h" |
8efc0c15 | 22 | #include "uidswap.h" |
23 | #include "compat.h" | |
6fa724bc | 24 | #include "readconf.h" |
4fe2af09 | 25 | #include "key.h" |
a306f2dd | 26 | #include "sshconnect.h" |
4fe2af09 | 27 | #include "hostfile.h" |
8efc0c15 | 28 | |
a306f2dd | 29 | char *client_version_string = NULL; |
30 | char *server_version_string = NULL; | |
8ce64345 | 31 | |
57112b5a | 32 | extern Options options; |
3fd95d9a | 33 | #ifdef HAVE___PROGNAME |
48e671d5 | 34 | extern char *__progname; |
3fd95d9a | 35 | #else /* HAVE___PROGNAME */ |
36 | static const char *__progname = "ssh"; | |
37 | #endif /* HAVE___PROGNAME */ | |
57112b5a | 38 | |
5260325f | 39 | /* |
40 | * Connect to the given ssh server using a proxy command. | |
41 | */ | |
8efc0c15 | 42 | int |
57112b5a | 43 | ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid, |
8efc0c15 | 44 | const char *proxy_command) |
45 | { | |
5260325f | 46 | Buffer command; |
47 | const char *cp; | |
48 | char *command_string; | |
49 | int pin[2], pout[2]; | |
9da5c3c9 | 50 | pid_t pid; |
48e671d5 | 51 | char strport[NI_MAXSERV]; |
5260325f | 52 | |
53 | /* Convert the port number into a string. */ | |
48e671d5 | 54 | snprintf(strport, sizeof strport, "%hu", port); |
5260325f | 55 | |
56 | /* Build the final command string in the buffer by making the | |
57 | appropriate substitutions to the given proxy command. */ | |
58 | buffer_init(&command); | |
59 | for (cp = proxy_command; *cp; cp++) { | |
60 | if (cp[0] == '%' && cp[1] == '%') { | |
61 | buffer_append(&command, "%", 1); | |
62 | cp++; | |
63 | continue; | |
64 | } | |
65 | if (cp[0] == '%' && cp[1] == 'h') { | |
66 | buffer_append(&command, host, strlen(host)); | |
67 | cp++; | |
68 | continue; | |
69 | } | |
70 | if (cp[0] == '%' && cp[1] == 'p') { | |
48e671d5 | 71 | buffer_append(&command, strport, strlen(strport)); |
5260325f | 72 | cp++; |
73 | continue; | |
74 | } | |
75 | buffer_append(&command, cp, 1); | |
8efc0c15 | 76 | } |
5260325f | 77 | buffer_append(&command, "\0", 1); |
78 | ||
79 | /* Get the final command string. */ | |
80 | command_string = buffer_ptr(&command); | |
81 | ||
82 | /* Create pipes for communicating with the proxy. */ | |
83 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
84 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
85 | strerror(errno)); | |
86 | ||
87 | debug("Executing proxy command: %.500s", command_string); | |
88 | ||
89 | /* Fork and execute the proxy command. */ | |
90 | if ((pid = fork()) == 0) { | |
91 | char *argv[10]; | |
92 | ||
93 | /* Child. Permanently give up superuser privileges. */ | |
94 | permanently_set_uid(original_real_uid); | |
95 | ||
96 | /* Redirect stdin and stdout. */ | |
97 | close(pin[1]); | |
98 | if (pin[0] != 0) { | |
99 | if (dup2(pin[0], 0) < 0) | |
100 | perror("dup2 stdin"); | |
101 | close(pin[0]); | |
102 | } | |
103 | close(pout[0]); | |
104 | if (dup2(pout[1], 1) < 0) | |
105 | perror("dup2 stdout"); | |
106 | /* Cannot be 1 because pin allocated two descriptors. */ | |
107 | close(pout[1]); | |
108 | ||
109 | /* Stderr is left as it is so that error messages get | |
110 | printed on the user's terminal. */ | |
111 | argv[0] = "/bin/sh"; | |
112 | argv[1] = "-c"; | |
113 | argv[2] = command_string; | |
114 | argv[3] = NULL; | |
115 | ||
116 | /* Execute the proxy command. Note that we gave up any | |
117 | extra privileges above. */ | |
118 | execv("/bin/sh", argv); | |
119 | perror("/bin/sh"); | |
120 | exit(1); | |
8efc0c15 | 121 | } |
5260325f | 122 | /* Parent. */ |
123 | if (pid < 0) | |
124 | fatal("fork failed: %.100s", strerror(errno)); | |
125 | ||
126 | /* Close child side of the descriptors. */ | |
127 | close(pin[0]); | |
128 | close(pout[1]); | |
129 | ||
130 | /* Free the command name. */ | |
131 | buffer_free(&command); | |
132 | ||
133 | /* Set the connection file descriptors. */ | |
134 | packet_set_connection(pout[0], pin[1]); | |
8efc0c15 | 135 | |
5260325f | 136 | return 1; |
137 | } | |
8efc0c15 | 138 | |
5260325f | 139 | /* |
140 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
141 | */ | |
142 | int | |
48e671d5 | 143 | ssh_create_socket(uid_t original_real_uid, int privileged, int family) |
8efc0c15 | 144 | { |
5260325f | 145 | int sock; |
146 | ||
aa3378df | 147 | /* |
148 | * If we are running as root and want to connect to a privileged | |
149 | * port, bind our own socket to a privileged port. | |
150 | */ | |
5260325f | 151 | if (privileged) { |
152 | int p = IPPORT_RESERVED - 1; | |
48e671d5 | 153 | sock = rresvport_af(&p, family); |
5260325f | 154 | if (sock < 0) |
c8d54615 | 155 | error("rresvport: af=%d %.100s", family, strerror(errno)); |
156 | else | |
157 | debug("Allocated local port %d.", p); | |
5260325f | 158 | } else { |
95f1eccc | 159 | /* |
160 | * Just create an ordinary socket on arbitrary port. We use | |
161 | * the user's uid to create the socket. | |
162 | */ | |
5260325f | 163 | temporarily_use_uid(original_real_uid); |
48e671d5 | 164 | sock = socket(family, SOCK_STREAM, 0); |
5260325f | 165 | if (sock < 0) |
48e671d5 | 166 | error("socket: %.100s", strerror(errno)); |
5260325f | 167 | restore_uid(); |
168 | } | |
169 | return sock; | |
8efc0c15 | 170 | } |
171 | ||
5260325f | 172 | /* |
48e671d5 | 173 | * Opens a TCP/IP connection to the remote server on the given host. |
174 | * The address of the remote host will be returned in hostaddr. | |
175 | * If port is 0, the default port will be used. If anonymous is zero, | |
5260325f | 176 | * a privileged port will be allocated to make the connection. |
177 | * This requires super-user privileges if anonymous is false. | |
178 | * Connection_attempts specifies the maximum number of tries (one per | |
179 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
180 | * and %p substituted for host and port, respectively) to use to contact | |
181 | * the daemon. | |
182 | */ | |
183 | int | |
48e671d5 | 184 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, |
57112b5a | 185 | u_short port, int connection_attempts, |
5260325f | 186 | int anonymous, uid_t original_real_uid, |
187 | const char *proxy_command) | |
8efc0c15 | 188 | { |
48e671d5 | 189 | int sock = -1, attempt; |
5260325f | 190 | struct servent *sp; |
48e671d5 | 191 | struct addrinfo hints, *ai, *aitop; |
192 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
193 | int gaierr; | |
5260325f | 194 | struct linger linger; |
195 | ||
196 | debug("ssh_connect: getuid %d geteuid %d anon %d", | |
197 | (int) getuid(), (int) geteuid(), anonymous); | |
198 | ||
199 | /* Get default port if port has not been set. */ | |
200 | if (port == 0) { | |
201 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
202 | if (sp) | |
203 | port = ntohs(sp->s_port); | |
204 | else | |
205 | port = SSH_DEFAULT_PORT; | |
8efc0c15 | 206 | } |
5260325f | 207 | /* If a proxy command is given, connect using it. */ |
208 | if (proxy_command != NULL) | |
209 | return ssh_proxy_connect(host, port, original_real_uid, proxy_command); | |
210 | ||
211 | /* No proxy command. */ | |
212 | ||
48e671d5 | 213 | memset(&hints, 0, sizeof(hints)); |
214 | hints.ai_family = IPv4or6; | |
215 | hints.ai_socktype = SOCK_STREAM; | |
216 | snprintf(strport, sizeof strport, "%d", port); | |
217 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) | |
218 | fatal("%s: %.100s: %s", __progname, host, | |
219 | gai_strerror(gaierr)); | |
5260325f | 220 | |
95f1eccc | 221 | /* |
222 | * Try to connect several times. On some machines, the first time | |
223 | * will sometimes fail. In general socket code appears to behave | |
224 | * quite magically on many machines. | |
225 | */ | |
5260325f | 226 | for (attempt = 0; attempt < connection_attempts; attempt++) { |
227 | if (attempt > 0) | |
228 | debug("Trying again..."); | |
229 | ||
48e671d5 | 230 | /* Loop through addresses for this host, and try each one in |
6ae2364d | 231 | sequence until the connection succeeds. */ |
48e671d5 | 232 | for (ai = aitop; ai; ai = ai->ai_next) { |
233 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
234 | continue; | |
235 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
236 | ntop, sizeof(ntop), strport, sizeof(strport), | |
237 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
238 | error("ssh_connect: getnameinfo failed"); | |
239 | continue; | |
240 | } | |
241 | debug("Connecting to %.200s [%.100s] port %s.", | |
242 | host, ntop, strport); | |
243 | ||
244 | /* Create a socket for connecting. */ | |
6ae2364d | 245 | sock = ssh_create_socket(original_real_uid, |
48e671d5 | 246 | !anonymous && geteuid() == 0 && port < IPPORT_RESERVED, |
247 | ai->ai_family); | |
248 | if (sock < 0) | |
249 | continue; | |
250 | ||
251 | /* Connect to the host. We use the user's uid in the | |
252 | * hope that it will help with tcp_wrappers showing | |
253 | * the remote uid as root. | |
aa3378df | 254 | */ |
5260325f | 255 | temporarily_use_uid(original_real_uid); |
48e671d5 | 256 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { |
257 | /* Successful connection. */ | |
3d1a1654 | 258 | memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); |
5260325f | 259 | restore_uid(); |
260 | break; | |
48e671d5 | 261 | } else { |
5260325f | 262 | debug("connect: %.100s", strerror(errno)); |
263 | restore_uid(); | |
aa3378df | 264 | /* |
265 | * Close the failed socket; there appear to | |
266 | * be some problems when reusing a socket for | |
267 | * which connect() has already returned an | |
268 | * error. | |
269 | */ | |
5260325f | 270 | shutdown(sock, SHUT_RDWR); |
271 | close(sock); | |
272 | } | |
8efc0c15 | 273 | } |
48e671d5 | 274 | if (ai) |
275 | break; /* Successful connection. */ | |
8efc0c15 | 276 | |
5260325f | 277 | /* Sleep a moment before retrying. */ |
278 | sleep(1); | |
279 | } | |
48e671d5 | 280 | |
281 | freeaddrinfo(aitop); | |
282 | ||
5260325f | 283 | /* Return failure if we didn't get a successful connection. */ |
284 | if (attempt >= connection_attempts) | |
285 | return 0; | |
8efc0c15 | 286 | |
5260325f | 287 | debug("Connection established."); |
8efc0c15 | 288 | |
aa3378df | 289 | /* |
290 | * Set socket options. We would like the socket to disappear as soon | |
291 | * as it has been closed for whatever reason. | |
292 | */ | |
293 | /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 294 | linger.l_onoff = 1; |
295 | linger.l_linger = 5; | |
296 | setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
8efc0c15 | 297 | |
5260325f | 298 | /* Set the connection. */ |
299 | packet_set_connection(sock, sock); | |
8efc0c15 | 300 | |
5260325f | 301 | return 1; |
8efc0c15 | 302 | } |
303 | ||
5260325f | 304 | /* |
305 | * Waits for the server identification string, and sends our own | |
306 | * identification string. | |
307 | */ | |
308 | void | |
309 | ssh_exchange_identification() | |
8efc0c15 | 310 | { |
5260325f | 311 | char buf[256], remote_version[256]; /* must be same size! */ |
a8be9f80 | 312 | int remote_major, remote_minor, i, mismatch; |
5260325f | 313 | int connection_in = packet_get_connection_in(); |
314 | int connection_out = packet_get_connection_out(); | |
5260325f | 315 | |
316 | /* Read other side\'s version identification. */ | |
317 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
c8d54615 | 318 | int len = read(connection_in, &buf[i], 1); |
319 | if (len < 0) | |
5260325f | 320 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); |
c8d54615 | 321 | if (len != 1) |
322 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
5260325f | 323 | if (buf[i] == '\r') { |
324 | buf[i] = '\n'; | |
325 | buf[i + 1] = 0; | |
8ce64345 | 326 | continue; /**XXX wait for \n */ |
5260325f | 327 | } |
328 | if (buf[i] == '\n') { | |
329 | buf[i + 1] = 0; | |
330 | break; | |
331 | } | |
8efc0c15 | 332 | } |
5260325f | 333 | buf[sizeof(buf) - 1] = 0; |
8ce64345 | 334 | server_version_string = xstrdup(buf); |
5260325f | 335 | |
aa3378df | 336 | /* |
337 | * Check that the versions match. In future this might accept | |
338 | * several versions and set appropriate flags to handle them. | |
339 | */ | |
8ce64345 | 340 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", |
341 | &remote_major, &remote_minor, remote_version) != 3) | |
5260325f | 342 | fatal("Bad remote protocol version identification: '%.100s'", buf); |
343 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
344 | remote_major, remote_minor, remote_version); | |
345 | ||
8ce64345 | 346 | compat_datafellows(remote_version); |
a8be9f80 | 347 | mismatch = 0; |
348 | ||
349 | switch(remote_major) { | |
350 | case 1: | |
351 | if (remote_minor == 99 && | |
352 | (options.protocol & SSH_PROTO_2) && | |
353 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
354 | enable_compat20(); | |
355 | break; | |
5260325f | 356 | } |
a8be9f80 | 357 | if (!(options.protocol & SSH_PROTO_1)) { |
358 | mismatch = 1; | |
359 | break; | |
360 | } | |
361 | if (remote_minor < 3) { | |
362 | fatal("Remote machine has too old SSH software version."); | |
363 | } else if (remote_minor == 3) { | |
364 | /* We speak 1.3, too. */ | |
365 | enable_compat13(); | |
366 | if (options.forward_agent) { | |
367 | log("Agent forwarding disabled for protocol 1.3"); | |
368 | options.forward_agent = 0; | |
369 | } | |
370 | } | |
371 | break; | |
372 | case 2: | |
373 | if (options.protocol & SSH_PROTO_2) { | |
374 | enable_compat20(); | |
375 | break; | |
376 | } | |
377 | /* FALLTHROUGH */ | |
6ae2364d | 378 | default: |
a8be9f80 | 379 | mismatch = 1; |
380 | break; | |
8efc0c15 | 381 | } |
a8be9f80 | 382 | if (mismatch) |
5260325f | 383 | fatal("Protocol major versions differ: %d vs. %d", |
a8be9f80 | 384 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
385 | remote_major); | |
a306f2dd | 386 | if (compat20) |
387 | packet_set_ssh2_format(); | |
5260325f | 388 | /* Send our own protocol version identification. */ |
389 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
a8be9f80 | 390 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
391 | compat20 ? PROTOCOL_MINOR_2 : PROTOCOL_MINOR_1, | |
8ce64345 | 392 | SSH_VERSION); |
a408af76 | 393 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) |
5260325f | 394 | fatal("write: %.100s", strerror(errno)); |
8ce64345 | 395 | client_version_string = xstrdup(buf); |
396 | chop(client_version_string); | |
397 | chop(server_version_string); | |
398 | debug("Local version string %.100s", client_version_string); | |
8efc0c15 | 399 | } |
400 | ||
5260325f | 401 | int |
402 | read_yes_or_no(const char *prompt, int defval) | |
8efc0c15 | 403 | { |
5260325f | 404 | char buf[1024]; |
405 | FILE *f; | |
406 | int retval = -1; | |
407 | ||
408 | if (isatty(0)) | |
409 | f = stdin; | |
410 | else | |
411 | f = fopen("/dev/tty", "rw"); | |
412 | ||
413 | if (f == NULL) | |
414 | return 0; | |
415 | ||
416 | fflush(stdout); | |
417 | ||
418 | while (1) { | |
419 | fprintf(stderr, "%s", prompt); | |
420 | if (fgets(buf, sizeof(buf), f) == NULL) { | |
421 | /* Print a newline (the prompt probably didn\'t have one). */ | |
422 | fprintf(stderr, "\n"); | |
423 | strlcpy(buf, "no", sizeof buf); | |
424 | } | |
425 | /* Remove newline from response. */ | |
426 | if (strchr(buf, '\n')) | |
427 | *strchr(buf, '\n') = 0; | |
428 | ||
429 | if (buf[0] == 0) | |
430 | retval = defval; | |
431 | if (strcmp(buf, "yes") == 0) | |
432 | retval = 1; | |
433 | if (strcmp(buf, "no") == 0) | |
434 | retval = 0; | |
435 | ||
436 | if (retval != -1) { | |
437 | if (f != stdin) | |
438 | fclose(f); | |
439 | return retval; | |
440 | } | |
8efc0c15 | 441 | } |
8efc0c15 | 442 | } |
443 | ||
5260325f | 444 | /* |
95f1eccc | 445 | * check whether the supplied host key is valid, return only if ok. |
5260325f | 446 | */ |
95f1eccc | 447 | |
5260325f | 448 | void |
a306f2dd | 449 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, |
450 | const char *user_hostfile, const char *system_hostfile) | |
8efc0c15 | 451 | { |
4fe2af09 | 452 | Key *file_key; |
1d1ffb87 | 453 | char *type = key_type(host_key); |
95f1eccc | 454 | char *ip = NULL; |
5260325f | 455 | char hostline[1000], *hostp; |
5260325f | 456 | HostStatus host_status; |
457 | HostStatus ip_status; | |
48e671d5 | 458 | int local = 0, host_ip_differ = 0; |
20af321f | 459 | int salen; |
48e671d5 | 460 | char ntop[NI_MAXHOST]; |
461 | ||
462 | /* | |
463 | * Force accepting of the host key for loopback/localhost. The | |
464 | * problem is that if the home directory is NFS-mounted to multiple | |
465 | * machines, localhost will refer to a different machine in each of | |
466 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
467 | * essentially disables host authentication for localhost; however, | |
468 | * this is probably not a real problem. | |
469 | */ | |
a306f2dd | 470 | /** hostaddr == 0! */ |
48e671d5 | 471 | switch (hostaddr->sa_family) { |
472 | case AF_INET: | |
473 | local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; | |
20af321f | 474 | salen = sizeof(struct sockaddr_in); |
48e671d5 | 475 | break; |
476 | case AF_INET6: | |
477 | local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
20af321f | 478 | salen = sizeof(struct sockaddr_in6); |
48e671d5 | 479 | break; |
480 | default: | |
481 | local = 0; | |
20af321f | 482 | salen = sizeof(struct sockaddr_storage); |
48e671d5 | 483 | break; |
484 | } | |
485 | if (local) { | |
486 | debug("Forcing accepting of host key for loopback/localhost."); | |
487 | return; | |
488 | } | |
5260325f | 489 | |
57112b5a | 490 | /* |
491 | * Turn off check_host_ip for proxy connects, since | |
492 | * we don't have the remote ip-address | |
493 | */ | |
494 | if (options.proxy_command != NULL && options.check_host_ip) | |
495 | options.check_host_ip = 0; | |
496 | ||
48e671d5 | 497 | if (options.check_host_ip) { |
20af321f | 498 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), |
48e671d5 | 499 | NULL, 0, NI_NUMERICHOST) != 0) |
500 | fatal("check_host_key: getnameinfo failed"); | |
501 | ip = xstrdup(ntop); | |
502 | } | |
5260325f | 503 | |
95f1eccc | 504 | /* |
505 | * Store the host key from the known host file in here so that we can | |
506 | * compare it with the key for the IP address. | |
507 | */ | |
4fe2af09 | 508 | file_key = key_new(host_key->type); |
5260325f | 509 | |
aa3378df | 510 | /* |
511 | * Check if the host key is present in the user\'s list of known | |
512 | * hosts or in the systemwide list. | |
513 | */ | |
a306f2dd | 514 | host_status = check_host_in_hostfile(user_hostfile, host, host_key, file_key); |
5260325f | 515 | if (host_status == HOST_NEW) |
a306f2dd | 516 | host_status = check_host_in_hostfile(system_hostfile, host, host_key, file_key); |
aa3378df | 517 | /* |
518 | * Also perform check for the ip address, skip the check if we are | |
519 | * localhost or the hostname was an ip address to begin with | |
520 | */ | |
5260325f | 521 | if (options.check_host_ip && !local && strcmp(host, ip)) { |
4fe2af09 | 522 | Key *ip_key = key_new(host_key->type); |
a306f2dd | 523 | ip_status = check_host_in_hostfile(user_hostfile, ip, host_key, ip_key); |
5260325f | 524 | |
525 | if (ip_status == HOST_NEW) | |
a306f2dd | 526 | ip_status = check_host_in_hostfile(system_hostfile, ip, host_key, ip_key); |
5260325f | 527 | if (host_status == HOST_CHANGED && |
4fe2af09 | 528 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) |
5260325f | 529 | host_ip_differ = 1; |
530 | ||
4fe2af09 | 531 | key_free(ip_key); |
5260325f | 532 | } else |
533 | ip_status = host_status; | |
534 | ||
4fe2af09 | 535 | key_free(file_key); |
5260325f | 536 | |
537 | switch (host_status) { | |
538 | case HOST_OK: | |
539 | /* The host is known and the key matches. */ | |
1d1ffb87 | 540 | debug("Host '%.200s' is known and matches the %s host key.", |
541 | host, type); | |
5260325f | 542 | if (options.check_host_ip) { |
543 | if (ip_status == HOST_NEW) { | |
a306f2dd | 544 | if (!add_host_to_hostfile(user_hostfile, ip, host_key)) |
1d1ffb87 | 545 | log("Failed to add the %s host key for IP address '%.30s' to the list of known hosts (%.30s).", |
546 | type, ip, user_hostfile); | |
5260325f | 547 | else |
1d1ffb87 | 548 | log("Warning: Permanently added the %s host key for IP address '%.30s' to the list of known hosts.", |
549 | type, ip); | |
5260325f | 550 | } else if (ip_status != HOST_OK) |
1d1ffb87 | 551 | log("Warning: the %s host key for '%.200s' differs from the key for the IP address '%.30s'", |
552 | type, host, ip); | |
5260325f | 553 | } |
554 | break; | |
555 | case HOST_NEW: | |
556 | /* The host is new. */ | |
557 | if (options.strict_host_key_checking == 1) { | |
558 | /* User has requested strict host key checking. We will not add the host key | |
559 | automatically. The only alternative left is to abort. */ | |
1d1ffb87 | 560 | fatal("No %s host key is known for %.200s and you have requested strict checking.", type, host); |
5260325f | 561 | } else if (options.strict_host_key_checking == 2) { |
562 | /* The default */ | |
563 | char prompt[1024]; | |
4fe2af09 | 564 | char *fp = key_fingerprint(host_key); |
5260325f | 565 | snprintf(prompt, sizeof(prompt), |
a408af76 | 566 | "The authenticity of host '%.200s' can't be established.\n" |
1d1ffb87 | 567 | "%s key fingerprint is %s.\n" |
a408af76 | 568 | "Are you sure you want to continue connecting (yes/no)? ", |
1d1ffb87 | 569 | host, type, fp); |
5260325f | 570 | if (!read_yes_or_no(prompt, -1)) |
571 | fatal("Aborted by user!\n"); | |
572 | } | |
573 | if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) { | |
574 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); | |
575 | hostp = hostline; | |
576 | } else | |
577 | hostp = host; | |
578 | ||
579 | /* If not in strict mode, add the key automatically to the local known_hosts file. */ | |
a306f2dd | 580 | if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) |
5260325f | 581 | log("Failed to add the host to the list of known hosts (%.500s).", |
a306f2dd | 582 | user_hostfile); |
5260325f | 583 | else |
1d1ffb87 | 584 | log("Warning: Permanently added '%.200s' (%s) to the list of known hosts.", |
585 | hostp, type); | |
5260325f | 586 | break; |
587 | case HOST_CHANGED: | |
588 | if (options.check_host_ip && host_ip_differ) { | |
589 | char *msg; | |
590 | if (ip_status == HOST_NEW) | |
591 | msg = "is unknown"; | |
592 | else if (ip_status == HOST_OK) | |
593 | msg = "is unchanged"; | |
594 | else | |
595 | msg = "has a different value"; | |
596 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
597 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
598 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1d1ffb87 | 599 | error("The %s host key for %s has changed,", type, host); |
5260325f | 600 | error("and the key for the according IP address %s", ip); |
601 | error("%s. This could either mean that", msg); | |
602 | error("DNS SPOOFING is happening or the IP address for the host"); | |
603 | error("and its host key have changed at the same time"); | |
604 | } | |
605 | /* The host key has changed. */ | |
606 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
ae2f7af7 | 607 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); |
5260325f | 608 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
609 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
610 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
1d1ffb87 | 611 | error("It is also possible that the %s host key has just been changed.", type); |
5260325f | 612 | error("Please contact your system administrator."); |
613 | error("Add correct host key in %.100s to get rid of this message.", | |
a306f2dd | 614 | user_hostfile); |
5260325f | 615 | |
aa3378df | 616 | /* |
617 | * If strict host key checking is in use, the user will have | |
618 | * to edit the key manually and we can only abort. | |
619 | */ | |
5260325f | 620 | if (options.strict_host_key_checking) |
1d1ffb87 | 621 | fatal("%s host key for %.200s has changed and you have requested strict checking.", type, host); |
5260325f | 622 | |
aa3378df | 623 | /* |
624 | * If strict host key checking has not been requested, allow | |
625 | * the connection but without password authentication or | |
626 | * agent forwarding. | |
627 | */ | |
5260325f | 628 | if (options.password_authentication) { |
629 | error("Password authentication is disabled to avoid trojan horses."); | |
630 | options.password_authentication = 0; | |
631 | } | |
632 | if (options.forward_agent) { | |
633 | error("Agent forwarding is disabled to avoid trojan horses."); | |
634 | options.forward_agent = 0; | |
635 | } | |
aa3378df | 636 | /* |
637 | * XXX Should permit the user to change to use the new id. | |
638 | * This could be done by converting the host key to an | |
639 | * identifying sentence, tell that the host identifies itself | |
640 | * by that sentence, and ask the user if he/she whishes to | |
641 | * accept the authentication. | |
642 | */ | |
5260325f | 643 | break; |
644 | } | |
5260325f | 645 | if (options.check_host_ip) |
646 | xfree(ip); | |
95f1eccc | 647 | } |
648 | ||
8ce64345 | 649 | /* |
a306f2dd | 650 | * Starts a dialog with the server, and authenticates the current user on the |
651 | * server. This does not need any extra privileges. The basic connection | |
652 | * to the server must already have been established before this is called. | |
653 | * If login fails, this function prints an error and never returns. | |
654 | * This function does not require super-user privileges. | |
8ce64345 | 655 | */ |
656 | void | |
a306f2dd | 657 | ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost, |
658 | struct sockaddr *hostaddr, uid_t original_real_uid) | |
8ce64345 | 659 | { |
8ce64345 | 660 | struct passwd *pw; |
a306f2dd | 661 | char *host, *cp; |
8ce64345 | 662 | char *server_user, *local_user; |
8ce64345 | 663 | |
8ce64345 | 664 | /* Get local user name. Use it as server user if no user name was given. */ |
665 | pw = getpwuid(original_real_uid); | |
666 | if (!pw) | |
667 | fatal("User id %d not found from user database.", original_real_uid); | |
668 | local_user = xstrdup(pw->pw_name); | |
669 | server_user = options.user ? options.user : local_user; | |
670 | ||
7b2ea3a1 | 671 | /* Convert the user-supplied hostname into all lowercase. */ |
672 | host = xstrdup(orighost); | |
673 | for (cp = host; *cp; cp++) | |
674 | if (isupper(*cp)) | |
675 | *cp = tolower(*cp); | |
676 | ||
677 | /* Exchange protocol version identification strings with the server. */ | |
678 | ssh_exchange_identification(); | |
679 | ||
680 | /* Put the connection into non-blocking mode. */ | |
681 | packet_set_nonblocking(); | |
682 | ||
7b2ea3a1 | 683 | /* key exchange */ |
7b2ea3a1 | 684 | /* authenticate user */ |
8ce64345 | 685 | if (compat20) { |
686 | ssh_kex2(host, hostaddr); | |
a306f2dd | 687 | ssh_userauth2(server_user, host); |
8ce64345 | 688 | } else { |
8ce64345 | 689 | ssh_kex(host, hostaddr); |
a306f2dd | 690 | ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key); |
8ce64345 | 691 | } |
7b2ea3a1 | 692 | } |