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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 16:36:11 1995 ylo | |
6 | * Ssh client program. This program can be used to log into a remote machine. | |
7 | * The software supports strong authentication, encryption, and forwarding | |
8 | * of X11, TCP/IP, and authentication connections. | |
9 | * | |
10 | * Modified to work with SSL by Niels Provos <provos@citi.umich.edu> in Canada. | |
11 | */ | |
8efc0c15 | 12 | |
13 | #include "includes.h" | |
14 | RCSID("$Id$"); | |
15 | ||
16 | #include "xmalloc.h" | |
17 | #include "ssh.h" | |
18 | #include "packet.h" | |
19 | #include "buffer.h" | |
20 | #include "authfd.h" | |
21 | #include "readconf.h" | |
22 | #include "uidswap.h" | |
23 | ||
f601d847 | 24 | #ifdef HAVE___PROGNAME |
25 | extern char *__progname; | |
26 | #else /* HAVE___PROGNAME */ | |
27 | const char *__progname = "ssh"; | |
28 | #endif /* HAVE___PROGNAME */ | |
29 | ||
5260325f | 30 | /* Flag indicating whether debug mode is on. This can be set on the command line. */ |
8efc0c15 | 31 | int debug_flag = 0; |
32 | ||
8efc0c15 | 33 | int tty_flag = 0; |
34 | ||
aa3378df | 35 | /* |
36 | * Flag indicating that nothing should be read from stdin. This can be set | |
37 | * on the command line. | |
38 | */ | |
8efc0c15 | 39 | int stdin_null_flag = 0; |
40 | ||
aa3378df | 41 | /* |
42 | * Flag indicating that ssh should fork after authentication. This is useful | |
43 | * so that the pasphrase can be entered manually, and then ssh goes to the | |
44 | * background. | |
45 | */ | |
8efc0c15 | 46 | int fork_after_authentication_flag = 0; |
47 | ||
aa3378df | 48 | /* |
49 | * General data structure for command line options and options configurable | |
50 | * in configuration files. See readconf.h. | |
51 | */ | |
8efc0c15 | 52 | Options options; |
53 | ||
aa3378df | 54 | /* |
55 | * Name of the host we are connecting to. This is the name given on the | |
56 | * command line, or the HostName specified for the user-supplied name in a | |
57 | * configuration file. | |
58 | */ | |
8efc0c15 | 59 | char *host; |
60 | ||
61 | /* socket address the host resolves to */ | |
62 | struct sockaddr_in hostaddr; | |
63 | ||
aa3378df | 64 | /* |
65 | * Flag to indicate that we have received a window change signal which has | |
66 | * not yet been processed. This will cause a message indicating the new | |
67 | * window size to be sent to the server a little later. This is volatile | |
68 | * because this is updated in a signal handler. | |
69 | */ | |
8efc0c15 | 70 | volatile int received_window_change_signal = 0; |
71 | ||
72 | /* Value of argv[0] (set in the main program). */ | |
73 | char *av0; | |
74 | ||
75 | /* Flag indicating whether we have a valid host private key loaded. */ | |
76 | int host_private_key_loaded = 0; | |
77 | ||
78 | /* Host private key. */ | |
79 | RSA *host_private_key = NULL; | |
80 | ||
81 | /* Original real UID. */ | |
82 | uid_t original_real_uid; | |
83 | ||
84 | /* Prints a help message to the user. This function never returns. */ | |
85 | ||
86 | void | |
87 | usage() | |
88 | { | |
5260325f | 89 | fprintf(stderr, "Usage: %s [options] host [command]\n", av0); |
90 | fprintf(stderr, "Options:\n"); | |
91 | fprintf(stderr, " -l user Log in using this user name.\n"); | |
92 | fprintf(stderr, " -n Redirect input from /dev/null.\n"); | |
93 | fprintf(stderr, " -a Disable authentication agent forwarding.\n"); | |
8efc0c15 | 94 | #ifdef AFS |
5260325f | 95 | fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n"); |
96 | #endif /* AFS */ | |
97 | fprintf(stderr, " -x Disable X11 connection forwarding.\n"); | |
98 | fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n"); | |
99 | fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n"); | |
100 | fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); | |
101 | fprintf(stderr, " -V Display version number only.\n"); | |
102 | fprintf(stderr, " -P Don't allocate a privileged port.\n"); | |
103 | fprintf(stderr, " -q Quiet; don't display any warning messages.\n"); | |
104 | fprintf(stderr, " -f Fork into background after authentication.\n"); | |
105 | fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n"); | |
106 | ||
107 | fprintf(stderr, " -c cipher Select encryption algorithm: " | |
108 | "``3des'', " | |
109 | "``blowfish''\n"); | |
110 | fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n"); | |
111 | fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n"); | |
112 | fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n"); | |
113 | fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0); | |
114 | fprintf(stderr, " forward them to the other side by connecting to host:port.\n"); | |
115 | fprintf(stderr, " -C Enable compression.\n"); | |
116 | fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n"); | |
117 | fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n"); | |
118 | exit(1); | |
8efc0c15 | 119 | } |
120 | ||
5260325f | 121 | /* |
122 | * Connects to the given host using rsh (or prints an error message and exits | |
123 | * if rsh is not available). This function never returns. | |
124 | */ | |
8efc0c15 | 125 | void |
5260325f | 126 | rsh_connect(char *host, char *user, Buffer * command) |
8efc0c15 | 127 | { |
5260325f | 128 | char *args[10]; |
129 | int i; | |
130 | ||
131 | log("Using rsh. WARNING: Connection will not be encrypted."); | |
132 | /* Build argument list for rsh. */ | |
133 | i = 0; | |
134 | args[i++] = _PATH_RSH; | |
135 | /* host may have to come after user on some systems */ | |
136 | args[i++] = host; | |
137 | if (user) { | |
138 | args[i++] = "-l"; | |
139 | args[i++] = user; | |
140 | } | |
141 | if (buffer_len(command) > 0) { | |
142 | buffer_append(command, "\0", 1); | |
143 | args[i++] = buffer_ptr(command); | |
144 | } | |
145 | args[i++] = NULL; | |
146 | if (debug_flag) { | |
147 | for (i = 0; args[i]; i++) { | |
148 | if (i != 0) | |
149 | fprintf(stderr, " "); | |
150 | fprintf(stderr, "%s", args[i]); | |
151 | } | |
152 | fprintf(stderr, "\n"); | |
8efc0c15 | 153 | } |
5260325f | 154 | execv(_PATH_RSH, args); |
155 | perror(_PATH_RSH); | |
156 | exit(1); | |
8efc0c15 | 157 | } |
158 | ||
5260325f | 159 | /* |
160 | * Main program for the ssh client. | |
161 | */ | |
8efc0c15 | 162 | int |
163 | main(int ac, char **av) | |
164 | { | |
57112b5a | 165 | int i, opt, optind, type, exit_status, ok, authfd; |
166 | u_short fwd_port, fwd_host_port; | |
5260325f | 167 | char *optarg, *cp, buf[256]; |
168 | Buffer command; | |
169 | struct winsize ws; | |
170 | struct stat st; | |
171 | struct passwd *pw, pwcopy; | |
172 | int interactive = 0, dummy; | |
173 | uid_t original_effective_uid; | |
174 | int plen; | |
175 | ||
aa3378df | 176 | /* |
177 | * Save the original real uid. It will be needed later (uid-swapping | |
178 | * may clobber the real uid). | |
179 | */ | |
5260325f | 180 | original_real_uid = getuid(); |
181 | original_effective_uid = geteuid(); | |
182 | ||
183 | /* If we are installed setuid root be careful to not drop core. */ | |
184 | if (original_real_uid != original_effective_uid) { | |
185 | struct rlimit rlim; | |
186 | rlim.rlim_cur = rlim.rlim_max = 0; | |
187 | if (setrlimit(RLIMIT_CORE, &rlim) < 0) | |
188 | fatal("setrlimit failed: %.100s", strerror(errno)); | |
8efc0c15 | 189 | } |
aa3378df | 190 | /* |
191 | * Use uid-swapping to give up root privileges for the duration of | |
192 | * option processing. We will re-instantiate the rights when we are | |
193 | * ready to create the privileged port, and will permanently drop | |
194 | * them when the port has been created (actually, when the connection | |
195 | * has been made, as we may need to create the port several times). | |
196 | */ | |
5260325f | 197 | temporarily_use_uid(original_real_uid); |
198 | ||
aa3378df | 199 | /* |
200 | * Set our umask to something reasonable, as some files are created | |
201 | * with the default umask. This will make them world-readable but | |
202 | * writable only by the owner, which is ok for all files for which we | |
203 | * don't set the modes explicitly. | |
204 | */ | |
5260325f | 205 | umask(022); |
206 | ||
207 | /* Save our own name. */ | |
208 | av0 = av[0]; | |
209 | ||
210 | /* Initialize option structure to indicate that no values have been set. */ | |
211 | initialize_options(&options); | |
212 | ||
213 | /* Parse command-line arguments. */ | |
214 | host = NULL; | |
215 | ||
216 | /* If program name is not one of the standard names, use it as host name. */ | |
217 | if (strchr(av0, '/')) | |
218 | cp = strrchr(av0, '/') + 1; | |
219 | else | |
220 | cp = av0; | |
221 | if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 && | |
222 | strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0) | |
223 | host = cp; | |
224 | ||
225 | for (optind = 1; optind < ac; optind++) { | |
226 | if (av[optind][0] != '-') { | |
227 | if (host) | |
228 | break; | |
229 | if ((cp = strchr(av[optind], '@'))) { | |
230 | options.user = av[optind]; | |
231 | *cp = '\0'; | |
232 | host = ++cp; | |
233 | } else | |
234 | host = av[optind]; | |
235 | continue; | |
236 | } | |
237 | opt = av[optind][1]; | |
238 | if (!opt) | |
239 | usage(); | |
240 | if (strchr("eilcpLRo", opt)) { /* options with arguments */ | |
241 | optarg = av[optind] + 2; | |
242 | if (strcmp(optarg, "") == 0) { | |
243 | if (optind >= ac - 1) | |
244 | usage(); | |
245 | optarg = av[++optind]; | |
246 | } | |
247 | } else { | |
248 | if (av[optind][2]) | |
249 | usage(); | |
250 | optarg = NULL; | |
251 | } | |
252 | switch (opt) { | |
253 | case 'n': | |
254 | stdin_null_flag = 1; | |
255 | break; | |
256 | ||
257 | case 'f': | |
258 | fork_after_authentication_flag = 1; | |
259 | stdin_null_flag = 1; | |
260 | break; | |
261 | ||
262 | case 'x': | |
263 | options.forward_x11 = 0; | |
264 | break; | |
265 | ||
266 | case 'X': | |
267 | options.forward_x11 = 1; | |
268 | break; | |
269 | ||
270 | case 'g': | |
271 | options.gateway_ports = 1; | |
272 | break; | |
273 | ||
274 | case 'P': | |
275 | options.use_privileged_port = 0; | |
276 | break; | |
277 | ||
278 | case 'a': | |
279 | options.forward_agent = 0; | |
280 | break; | |
281 | #ifdef AFS | |
282 | case 'k': | |
283 | options.kerberos_tgt_passing = 0; | |
284 | options.afs_token_passing = 0; | |
285 | break; | |
286 | #endif | |
287 | case 'i': | |
288 | if (stat(optarg, &st) < 0) { | |
289 | fprintf(stderr, "Warning: Identity file %s does not exist.\n", | |
290 | optarg); | |
291 | break; | |
292 | } | |
293 | if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES) | |
294 | fatal("Too many identity files specified (max %d)", | |
295 | SSH_MAX_IDENTITY_FILES); | |
296 | options.identity_files[options.num_identity_files++] = | |
297 | xstrdup(optarg); | |
298 | break; | |
299 | ||
300 | case 't': | |
301 | tty_flag = 1; | |
302 | break; | |
303 | ||
304 | case 'v': | |
305 | case 'V': | |
306 | fprintf(stderr, "SSH Version %s, protocol version %d.%d.\n", | |
307 | SSH_VERSION, PROTOCOL_MAJOR, PROTOCOL_MINOR); | |
308 | fprintf(stderr, "Compiled with SSL.\n"); | |
309 | if (opt == 'V') | |
310 | exit(0); | |
311 | debug_flag = 1; | |
312 | options.log_level = SYSLOG_LEVEL_DEBUG; | |
313 | break; | |
314 | ||
315 | case 'q': | |
316 | options.log_level = SYSLOG_LEVEL_QUIET; | |
317 | break; | |
318 | ||
319 | case 'e': | |
320 | if (optarg[0] == '^' && optarg[2] == 0 && | |
321 | (unsigned char) optarg[1] >= 64 && (unsigned char) optarg[1] < 128) | |
322 | options.escape_char = (unsigned char) optarg[1] & 31; | |
323 | else if (strlen(optarg) == 1) | |
324 | options.escape_char = (unsigned char) optarg[0]; | |
325 | else if (strcmp(optarg, "none") == 0) | |
326 | options.escape_char = -2; | |
327 | else { | |
328 | fprintf(stderr, "Bad escape character '%s'.\n", optarg); | |
329 | exit(1); | |
330 | } | |
331 | break; | |
332 | ||
333 | case 'c': | |
334 | options.cipher = cipher_number(optarg); | |
335 | if (options.cipher == -1) { | |
336 | fprintf(stderr, "Unknown cipher type '%s'\n", optarg); | |
337 | exit(1); | |
338 | } | |
339 | break; | |
340 | ||
341 | case 'p': | |
342 | options.port = atoi(optarg); | |
5260325f | 343 | break; |
344 | ||
345 | case 'l': | |
346 | options.user = optarg; | |
347 | break; | |
348 | ||
349 | case 'R': | |
57112b5a | 350 | if (sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, |
5260325f | 351 | &fwd_host_port) != 3) { |
352 | fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); | |
353 | usage(); | |
354 | /* NOTREACHED */ | |
355 | } | |
356 | add_remote_forward(&options, fwd_port, buf, fwd_host_port); | |
357 | break; | |
358 | ||
359 | case 'L': | |
57112b5a | 360 | if (sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, |
5260325f | 361 | &fwd_host_port) != 3) { |
362 | fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); | |
363 | usage(); | |
364 | /* NOTREACHED */ | |
365 | } | |
366 | add_local_forward(&options, fwd_port, buf, fwd_host_port); | |
367 | break; | |
368 | ||
369 | case 'C': | |
370 | options.compression = 1; | |
371 | break; | |
372 | ||
373 | case 'o': | |
374 | dummy = 1; | |
375 | if (process_config_line(&options, host ? host : "", optarg, | |
376 | "command-line", 0, &dummy) != 0) | |
377 | exit(1); | |
378 | break; | |
379 | ||
380 | default: | |
381 | usage(); | |
382 | } | |
383 | } | |
384 | ||
385 | /* Check that we got a host name. */ | |
386 | if (!host) | |
8efc0c15 | 387 | usage(); |
5260325f | 388 | |
389 | /* check if RSA support exists */ | |
390 | if (rsa_alive() == 0) { | |
391 | fprintf(stderr, | |
392 | "%s: no RSA support in libssl and libcrypto. See ssl(8).\n", | |
393 | __progname); | |
394 | exit(1); | |
8efc0c15 | 395 | } |
5260325f | 396 | /* Initialize the command to execute on remote host. */ |
397 | buffer_init(&command); | |
398 | ||
aa3378df | 399 | /* |
400 | * Save the command to execute on the remote host in a buffer. There | |
401 | * is no limit on the length of the command, except by the maximum | |
402 | * packet size. Also sets the tty flag if there is no command. | |
403 | */ | |
5260325f | 404 | if (optind == ac) { |
405 | /* No command specified - execute shell on a tty. */ | |
406 | tty_flag = 1; | |
407 | } else { | |
408 | /* A command has been specified. Store it into the | |
409 | buffer. */ | |
410 | for (i = optind; i < ac; i++) { | |
411 | if (i > optind) | |
412 | buffer_append(&command, " ", 1); | |
413 | buffer_append(&command, av[i], strlen(av[i])); | |
414 | } | |
8efc0c15 | 415 | } |
5260325f | 416 | |
417 | /* Cannot fork to background if no command. */ | |
418 | if (fork_after_authentication_flag && buffer_len(&command) == 0) | |
419 | fatal("Cannot fork into background without a command to execute."); | |
420 | ||
421 | /* Allocate a tty by default if no command specified. */ | |
422 | if (buffer_len(&command) == 0) | |
423 | tty_flag = 1; | |
424 | ||
425 | /* Do not allocate a tty if stdin is not a tty. */ | |
426 | if (!isatty(fileno(stdin))) { | |
427 | if (tty_flag) | |
428 | fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n"); | |
429 | tty_flag = 0; | |
430 | } | |
431 | /* Get user data. */ | |
432 | pw = getpwuid(original_real_uid); | |
433 | if (!pw) { | |
434 | fprintf(stderr, "You don't exist, go away!\n"); | |
435 | exit(1); | |
436 | } | |
437 | /* Take a copy of the returned structure. */ | |
438 | memset(&pwcopy, 0, sizeof(pwcopy)); | |
439 | pwcopy.pw_name = xstrdup(pw->pw_name); | |
440 | pwcopy.pw_passwd = xstrdup(pw->pw_passwd); | |
441 | pwcopy.pw_uid = pw->pw_uid; | |
442 | pwcopy.pw_gid = pw->pw_gid; | |
443 | pwcopy.pw_dir = xstrdup(pw->pw_dir); | |
444 | pwcopy.pw_shell = xstrdup(pw->pw_shell); | |
445 | pw = &pwcopy; | |
446 | ||
447 | /* Initialize "log" output. Since we are the client all output | |
448 | actually goes to the terminal. */ | |
449 | log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); | |
450 | ||
451 | /* Read per-user configuration file. */ | |
452 | snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE); | |
453 | read_config_file(buf, host, &options); | |
454 | ||
455 | /* Read systemwide configuration file. */ | |
456 | read_config_file(HOST_CONFIG_FILE, host, &options); | |
457 | ||
458 | /* Fill configuration defaults. */ | |
459 | fill_default_options(&options); | |
460 | ||
461 | /* reinit */ | |
462 | log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); | |
463 | ||
464 | if (options.user == NULL) | |
465 | options.user = xstrdup(pw->pw_name); | |
466 | ||
467 | if (options.hostname != NULL) | |
468 | host = options.hostname; | |
469 | ||
470 | /* Find canonic host name. */ | |
471 | if (strchr(host, '.') == 0) { | |
472 | struct hostent *hp = gethostbyname(host); | |
473 | if (hp != 0) { | |
474 | if (strchr(hp->h_name, '.') != 0) | |
475 | host = xstrdup(hp->h_name); | |
476 | else if (hp->h_aliases != 0 | |
477 | && hp->h_aliases[0] != 0 | |
478 | && strchr(hp->h_aliases[0], '.') != 0) | |
479 | host = xstrdup(hp->h_aliases[0]); | |
8efc0c15 | 480 | } |
8efc0c15 | 481 | } |
5260325f | 482 | /* Disable rhosts authentication if not running as root. */ |
483 | if (original_effective_uid != 0 || !options.use_privileged_port) { | |
484 | options.rhosts_authentication = 0; | |
485 | options.rhosts_rsa_authentication = 0; | |
486 | } | |
aa3378df | 487 | /* |
488 | * If using rsh has been selected, exec it now (without trying | |
489 | * anything else). Note that we must release privileges first. | |
490 | */ | |
5260325f | 491 | if (options.use_rsh) { |
aa3378df | 492 | /* |
493 | * Restore our superuser privileges. This must be done | |
494 | * before permanently setting the uid. | |
495 | */ | |
5260325f | 496 | restore_uid(); |
497 | ||
498 | /* Switch to the original uid permanently. */ | |
499 | permanently_set_uid(original_real_uid); | |
500 | ||
501 | /* Execute rsh. */ | |
502 | rsh_connect(host, options.user, &command); | |
503 | fatal("rsh_connect returned"); | |
8efc0c15 | 504 | } |
5260325f | 505 | /* Restore our superuser privileges. */ |
506 | restore_uid(); | |
507 | ||
aa3378df | 508 | /* |
509 | * Open a connection to the remote host. This needs root privileges | |
510 | * if rhosts_{rsa_}authentication is enabled. | |
511 | */ | |
5260325f | 512 | |
513 | ok = ssh_connect(host, &hostaddr, options.port, | |
514 | options.connection_attempts, | |
515 | !options.rhosts_authentication && | |
516 | !options.rhosts_rsa_authentication, | |
517 | original_real_uid, | |
518 | options.proxy_command); | |
519 | ||
aa3378df | 520 | /* |
521 | * If we successfully made the connection, load the host private key | |
522 | * in case we will need it later for combined rsa-rhosts | |
523 | * authentication. This must be done before releasing extra | |
524 | * privileges, because the file is only readable by root. | |
525 | */ | |
5260325f | 526 | if (ok) { |
527 | host_private_key = RSA_new(); | |
528 | if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL)) | |
529 | host_private_key_loaded = 1; | |
530 | } | |
aa3378df | 531 | /* |
532 | * Get rid of any extra privileges that we may have. We will no | |
533 | * longer need them. Also, extra privileges could make it very hard | |
534 | * to read identity files and other non-world-readable files from the | |
535 | * user's home directory if it happens to be on a NFS volume where | |
536 | * root is mapped to nobody. | |
537 | */ | |
538 | ||
539 | /* | |
540 | * Note that some legacy systems need to postpone the following call | |
541 | * to permanently_set_uid() until the private hostkey is destroyed | |
542 | * with RSA_free(). Otherwise the calling user could ptrace() the | |
543 | * process, read the private hostkey and impersonate the host. | |
544 | * OpenBSD does not allow ptracing of setuid processes. | |
545 | */ | |
5260325f | 546 | permanently_set_uid(original_real_uid); |
547 | ||
aa3378df | 548 | /* |
549 | * Now that we are back to our own permissions, create ~/.ssh | |
550 | * directory if it doesn\'t already exist. | |
551 | */ | |
5260325f | 552 | snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR); |
553 | if (stat(buf, &st) < 0) | |
554 | if (mkdir(buf, 0755) < 0) | |
555 | error("Could not create directory '%.200s'.", buf); | |
556 | ||
557 | /* Check if the connection failed, and try "rsh" if appropriate. */ | |
558 | if (!ok) { | |
559 | if (options.port != 0) | |
57112b5a | 560 | log("Secure connection to %.100s on port %hu refused%.100s.", |
5260325f | 561 | host, options.port, |
562 | options.fallback_to_rsh ? "; reverting to insecure method" : ""); | |
563 | else | |
564 | log("Secure connection to %.100s refused%.100s.", host, | |
565 | options.fallback_to_rsh ? "; reverting to insecure method" : ""); | |
566 | ||
567 | if (options.fallback_to_rsh) { | |
568 | rsh_connect(host, options.user, &command); | |
569 | fatal("rsh_connect returned"); | |
570 | } | |
571 | exit(1); | |
8efc0c15 | 572 | } |
5260325f | 573 | /* Expand ~ in options.identity_files. */ |
574 | for (i = 0; i < options.num_identity_files; i++) | |
575 | options.identity_files[i] = | |
576 | tilde_expand_filename(options.identity_files[i], original_real_uid); | |
577 | ||
578 | /* Expand ~ in known host file names. */ | |
579 | options.system_hostfile = tilde_expand_filename(options.system_hostfile, | |
580 | original_real_uid); | |
581 | options.user_hostfile = tilde_expand_filename(options.user_hostfile, | |
582 | original_real_uid); | |
583 | ||
584 | /* Log into the remote system. This never returns if the login fails. */ | |
585 | ssh_login(host_private_key_loaded, host_private_key, | |
586 | host, &hostaddr, original_real_uid); | |
587 | ||
588 | /* We no longer need the host private key. Clear it now. */ | |
589 | if (host_private_key_loaded) | |
590 | RSA_free(host_private_key); /* Destroys contents safely */ | |
591 | ||
592 | /* Close connection cleanly after attack. */ | |
593 | cipher_attack_detected = packet_disconnect; | |
594 | ||
5260325f | 595 | /* Enable compression if requested. */ |
596 | if (options.compression) { | |
597 | debug("Requesting compression at level %d.", options.compression_level); | |
598 | ||
599 | if (options.compression_level < 1 || options.compression_level > 9) | |
600 | fatal("Compression level must be from 1 (fast) to 9 (slow, best)."); | |
601 | ||
602 | /* Send the request. */ | |
603 | packet_start(SSH_CMSG_REQUEST_COMPRESSION); | |
604 | packet_put_int(options.compression_level); | |
605 | packet_send(); | |
606 | packet_write_wait(); | |
607 | type = packet_read(&plen); | |
608 | if (type == SSH_SMSG_SUCCESS) | |
609 | packet_start_compression(options.compression_level); | |
610 | else if (type == SSH_SMSG_FAILURE) | |
611 | log("Warning: Remote host refused compression."); | |
612 | else | |
613 | packet_disconnect("Protocol error waiting for compression response."); | |
614 | } | |
615 | /* Allocate a pseudo tty if appropriate. */ | |
616 | if (tty_flag) { | |
617 | debug("Requesting pty."); | |
618 | ||
619 | /* Start the packet. */ | |
620 | packet_start(SSH_CMSG_REQUEST_PTY); | |
621 | ||
622 | /* Store TERM in the packet. There is no limit on the | |
623 | length of the string. */ | |
624 | cp = getenv("TERM"); | |
625 | if (!cp) | |
626 | cp = ""; | |
627 | packet_put_string(cp, strlen(cp)); | |
628 | ||
629 | /* Store window size in the packet. */ | |
630 | if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) | |
631 | memset(&ws, 0, sizeof(ws)); | |
632 | packet_put_int(ws.ws_row); | |
633 | packet_put_int(ws.ws_col); | |
634 | packet_put_int(ws.ws_xpixel); | |
635 | packet_put_int(ws.ws_ypixel); | |
636 | ||
637 | /* Store tty modes in the packet. */ | |
638 | tty_make_modes(fileno(stdin)); | |
639 | ||
640 | /* Send the packet, and wait for it to leave. */ | |
641 | packet_send(); | |
642 | packet_write_wait(); | |
643 | ||
644 | /* Read response from the server. */ | |
645 | type = packet_read(&plen); | |
646 | if (type == SSH_SMSG_SUCCESS) | |
647 | interactive = 1; | |
648 | else if (type == SSH_SMSG_FAILURE) | |
649 | log("Warning: Remote host failed or refused to allocate a pseudo tty."); | |
650 | else | |
651 | packet_disconnect("Protocol error waiting for pty request response."); | |
652 | } | |
653 | /* Request X11 forwarding if enabled and DISPLAY is set. */ | |
654 | if (options.forward_x11 && getenv("DISPLAY") != NULL) { | |
655 | char line[512], proto[512], data[512]; | |
656 | FILE *f; | |
657 | int forwarded = 0, got_data = 0, i; | |
8efc0c15 | 658 | |
659 | #ifdef XAUTH_PATH | |
5260325f | 660 | /* Try to get Xauthority information for the display. */ |
661 | snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null", | |
662 | XAUTH_PATH, getenv("DISPLAY")); | |
663 | f = popen(line, "r"); | |
664 | if (f && fgets(line, sizeof(line), f) && | |
665 | sscanf(line, "%*s %s %s", proto, data) == 2) | |
666 | got_data = 1; | |
667 | if (f) | |
668 | pclose(f); | |
8efc0c15 | 669 | #endif /* XAUTH_PATH */ |
aa3378df | 670 | /* |
671 | * If we didn't get authentication data, just make up some | |
672 | * data. The forwarding code will check the validity of the | |
673 | * response anyway, and substitute this data. The X11 | |
674 | * server, however, will ignore this fake data and use | |
675 | * whatever authentication mechanisms it was using otherwise | |
676 | * for the local connection. | |
677 | */ | |
5260325f | 678 | if (!got_data) { |
679 | u_int32_t rand = 0; | |
680 | ||
681 | strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto); | |
682 | for (i = 0; i < 16; i++) { | |
683 | if (i % 4 == 0) | |
684 | rand = arc4random(); | |
685 | snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff); | |
686 | rand >>= 8; | |
687 | } | |
688 | } | |
aa3378df | 689 | /* |
690 | * Got local authentication reasonable information. Request | |
691 | * forwarding with authentication spoofing. | |
692 | */ | |
5260325f | 693 | debug("Requesting X11 forwarding with authentication spoofing."); |
694 | x11_request_forwarding_with_spoofing(proto, data); | |
695 | ||
696 | /* Read response from the server. */ | |
697 | type = packet_read(&plen); | |
698 | if (type == SSH_SMSG_SUCCESS) { | |
699 | forwarded = 1; | |
700 | interactive = 1; | |
701 | } else if (type == SSH_SMSG_FAILURE) | |
702 | log("Warning: Remote host denied X11 forwarding."); | |
703 | else | |
704 | packet_disconnect("Protocol error waiting for X11 forwarding"); | |
705 | } | |
706 | /* Tell the packet module whether this is an interactive session. */ | |
707 | packet_set_interactive(interactive, options.keepalives); | |
708 | ||
709 | /* Clear agent forwarding if we don\'t have an agent. */ | |
710 | authfd = ssh_get_authentication_socket(); | |
711 | if (authfd < 0) | |
712 | options.forward_agent = 0; | |
713 | else | |
714 | ssh_close_authentication_socket(authfd); | |
715 | ||
716 | /* Request authentication agent forwarding if appropriate. */ | |
717 | if (options.forward_agent) { | |
718 | debug("Requesting authentication agent forwarding."); | |
719 | auth_request_forwarding(); | |
720 | ||
721 | /* Read response from the server. */ | |
722 | type = packet_read(&plen); | |
723 | packet_integrity_check(plen, 0, type); | |
724 | if (type != SSH_SMSG_SUCCESS) | |
725 | log("Warning: Remote host denied authentication agent forwarding."); | |
726 | } | |
727 | /* Initiate local TCP/IP port forwardings. */ | |
728 | for (i = 0; i < options.num_local_forwards; i++) { | |
729 | debug("Connections to local port %d forwarded to remote address %.200s:%d", | |
730 | options.local_forwards[i].port, | |
731 | options.local_forwards[i].host, | |
732 | options.local_forwards[i].host_port); | |
733 | channel_request_local_forwarding(options.local_forwards[i].port, | |
734 | options.local_forwards[i].host, | |
735 | options.local_forwards[i].host_port); | |
8efc0c15 | 736 | } |
737 | ||
5260325f | 738 | /* Initiate remote TCP/IP port forwardings. */ |
739 | for (i = 0; i < options.num_remote_forwards; i++) { | |
740 | debug("Connections to remote port %d forwarded to local address %.200s:%d", | |
741 | options.remote_forwards[i].port, | |
742 | options.remote_forwards[i].host, | |
743 | options.remote_forwards[i].host_port); | |
744 | channel_request_remote_forwarding(options.remote_forwards[i].port, | |
745 | options.remote_forwards[i].host, | |
746 | options.remote_forwards[i].host_port); | |
8efc0c15 | 747 | } |
5260325f | 748 | |
aa3378df | 749 | /* If requested, let ssh continue in the background. */ |
750 | if (fork_after_authentication_flag) | |
751 | if (daemon(1, 1) < 0) | |
752 | fatal("daemon() failed: %.200s", strerror(errno)); | |
753 | ||
754 | /* | |
755 | * If a command was specified on the command line, execute the | |
756 | * command now. Otherwise request the server to start a shell. | |
757 | */ | |
5260325f | 758 | if (buffer_len(&command) > 0) { |
759 | int len = buffer_len(&command); | |
760 | if (len > 900) | |
761 | len = 900; | |
762 | debug("Sending command: %.*s", len, buffer_ptr(&command)); | |
763 | packet_start(SSH_CMSG_EXEC_CMD); | |
764 | packet_put_string(buffer_ptr(&command), buffer_len(&command)); | |
765 | packet_send(); | |
766 | packet_write_wait(); | |
767 | } else { | |
768 | debug("Requesting shell."); | |
769 | packet_start(SSH_CMSG_EXEC_SHELL); | |
770 | packet_send(); | |
771 | packet_write_wait(); | |
772 | } | |
773 | ||
774 | /* Enter the interactive session. */ | |
775 | exit_status = client_loop(tty_flag, tty_flag ? options.escape_char : -1); | |
776 | ||
777 | /* Close the connection to the remote host. */ | |
778 | packet_close(); | |
779 | ||
780 | /* Exit with the status returned by the program on the remote side. */ | |
781 | exit(exit_status); | |
8efc0c15 | 782 | } |