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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 | ||
48e671d5 | 30 | /* Flag indicating whether IPv4 or IPv6. This can be set on the command line. |
31 | Default value is AF_UNSPEC means both IPv4 and IPv6. */ | |
59e76f33 | 32 | #ifdef IPV4_DEFAULT |
33 | int IPv4or6 = AF_INET; | |
34 | #else | |
48e671d5 | 35 | int IPv4or6 = AF_UNSPEC; |
59e76f33 | 36 | #endif |
48e671d5 | 37 | |
5260325f | 38 | /* Flag indicating whether debug mode is on. This can be set on the command line. */ |
8efc0c15 | 39 | int debug_flag = 0; |
40 | ||
8efc0c15 | 41 | int tty_flag = 0; |
42 | ||
aa3378df | 43 | /* |
44 | * Flag indicating that nothing should be read from stdin. This can be set | |
45 | * on the command line. | |
46 | */ | |
8efc0c15 | 47 | int stdin_null_flag = 0; |
48 | ||
aa3378df | 49 | /* |
50 | * Flag indicating that ssh should fork after authentication. This is useful | |
51 | * so that the pasphrase can be entered manually, and then ssh goes to the | |
52 | * background. | |
53 | */ | |
8efc0c15 | 54 | int fork_after_authentication_flag = 0; |
55 | ||
aa3378df | 56 | /* |
57 | * General data structure for command line options and options configurable | |
58 | * in configuration files. See readconf.h. | |
59 | */ | |
8efc0c15 | 60 | Options options; |
61 | ||
aa3378df | 62 | /* |
63 | * Name of the host we are connecting to. This is the name given on the | |
64 | * command line, or the HostName specified for the user-supplied name in a | |
65 | * configuration file. | |
66 | */ | |
8efc0c15 | 67 | char *host; |
68 | ||
69 | /* socket address the host resolves to */ | |
48e671d5 | 70 | struct sockaddr_storage hostaddr; |
8efc0c15 | 71 | |
aa3378df | 72 | /* |
73 | * Flag to indicate that we have received a window change signal which has | |
74 | * not yet been processed. This will cause a message indicating the new | |
75 | * window size to be sent to the server a little later. This is volatile | |
76 | * because this is updated in a signal handler. | |
77 | */ | |
8efc0c15 | 78 | volatile int received_window_change_signal = 0; |
79 | ||
80 | /* Value of argv[0] (set in the main program). */ | |
81 | char *av0; | |
82 | ||
83 | /* Flag indicating whether we have a valid host private key loaded. */ | |
84 | int host_private_key_loaded = 0; | |
85 | ||
86 | /* Host private key. */ | |
87 | RSA *host_private_key = NULL; | |
88 | ||
89 | /* Original real UID. */ | |
90 | uid_t original_real_uid; | |
91 | ||
92 | /* Prints a help message to the user. This function never returns. */ | |
93 | ||
94 | void | |
95 | usage() | |
96 | { | |
5260325f | 97 | fprintf(stderr, "Usage: %s [options] host [command]\n", av0); |
98 | fprintf(stderr, "Options:\n"); | |
99 | fprintf(stderr, " -l user Log in using this user name.\n"); | |
100 | fprintf(stderr, " -n Redirect input from /dev/null.\n"); | |
101 | fprintf(stderr, " -a Disable authentication agent forwarding.\n"); | |
8efc0c15 | 102 | #ifdef AFS |
5260325f | 103 | fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n"); |
104 | #endif /* AFS */ | |
105 | fprintf(stderr, " -x Disable X11 connection forwarding.\n"); | |
c8d54615 | 106 | fprintf(stderr, " -X Enable X11 connection forwarding.\n"); |
5260325f | 107 | fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n"); |
108 | fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n"); | |
109 | fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); | |
110 | fprintf(stderr, " -V Display version number only.\n"); | |
111 | fprintf(stderr, " -P Don't allocate a privileged port.\n"); | |
112 | fprintf(stderr, " -q Quiet; don't display any warning messages.\n"); | |
113 | fprintf(stderr, " -f Fork into background after authentication.\n"); | |
114 | fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n"); | |
115 | ||
116 | fprintf(stderr, " -c cipher Select encryption algorithm: " | |
117 | "``3des'', " | |
118 | "``blowfish''\n"); | |
119 | fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n"); | |
120 | fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n"); | |
121 | fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n"); | |
122 | fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0); | |
123 | fprintf(stderr, " forward them to the other side by connecting to host:port.\n"); | |
124 | fprintf(stderr, " -C Enable compression.\n"); | |
125 | fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n"); | |
48e671d5 | 126 | fprintf(stderr, " -4 Use IPv4 only.\n"); |
127 | fprintf(stderr, " -6 Use IPv6 only.\n"); | |
5260325f | 128 | fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n"); |
129 | exit(1); | |
8efc0c15 | 130 | } |
131 | ||
5260325f | 132 | /* |
133 | * Connects to the given host using rsh (or prints an error message and exits | |
134 | * if rsh is not available). This function never returns. | |
135 | */ | |
8efc0c15 | 136 | void |
5260325f | 137 | rsh_connect(char *host, char *user, Buffer * command) |
8efc0c15 | 138 | { |
5260325f | 139 | char *args[10]; |
140 | int i; | |
141 | ||
142 | log("Using rsh. WARNING: Connection will not be encrypted."); | |
143 | /* Build argument list for rsh. */ | |
144 | i = 0; | |
145 | args[i++] = _PATH_RSH; | |
146 | /* host may have to come after user on some systems */ | |
147 | args[i++] = host; | |
148 | if (user) { | |
149 | args[i++] = "-l"; | |
150 | args[i++] = user; | |
151 | } | |
152 | if (buffer_len(command) > 0) { | |
153 | buffer_append(command, "\0", 1); | |
154 | args[i++] = buffer_ptr(command); | |
155 | } | |
156 | args[i++] = NULL; | |
157 | if (debug_flag) { | |
158 | for (i = 0; args[i]; i++) { | |
159 | if (i != 0) | |
160 | fprintf(stderr, " "); | |
161 | fprintf(stderr, "%s", args[i]); | |
162 | } | |
163 | fprintf(stderr, "\n"); | |
8efc0c15 | 164 | } |
5260325f | 165 | execv(_PATH_RSH, args); |
166 | perror(_PATH_RSH); | |
167 | exit(1); | |
8efc0c15 | 168 | } |
169 | ||
5260325f | 170 | /* |
171 | * Main program for the ssh client. | |
172 | */ | |
8efc0c15 | 173 | int |
174 | main(int ac, char **av) | |
175 | { | |
57112b5a | 176 | int i, opt, optind, type, exit_status, ok, authfd; |
177 | u_short fwd_port, fwd_host_port; | |
5260325f | 178 | char *optarg, *cp, buf[256]; |
179 | Buffer command; | |
180 | struct winsize ws; | |
181 | struct stat st; | |
182 | struct passwd *pw, pwcopy; | |
183 | int interactive = 0, dummy; | |
184 | uid_t original_effective_uid; | |
185 | int plen; | |
186 | ||
aa3378df | 187 | /* |
188 | * Save the original real uid. It will be needed later (uid-swapping | |
189 | * may clobber the real uid). | |
190 | */ | |
5260325f | 191 | original_real_uid = getuid(); |
192 | original_effective_uid = geteuid(); | |
193 | ||
194 | /* If we are installed setuid root be careful to not drop core. */ | |
195 | if (original_real_uid != original_effective_uid) { | |
196 | struct rlimit rlim; | |
197 | rlim.rlim_cur = rlim.rlim_max = 0; | |
198 | if (setrlimit(RLIMIT_CORE, &rlim) < 0) | |
199 | fatal("setrlimit failed: %.100s", strerror(errno)); | |
8efc0c15 | 200 | } |
aa3378df | 201 | /* |
202 | * Use uid-swapping to give up root privileges for the duration of | |
203 | * option processing. We will re-instantiate the rights when we are | |
204 | * ready to create the privileged port, and will permanently drop | |
205 | * them when the port has been created (actually, when the connection | |
206 | * has been made, as we may need to create the port several times). | |
207 | */ | |
5260325f | 208 | temporarily_use_uid(original_real_uid); |
209 | ||
aa3378df | 210 | /* |
211 | * Set our umask to something reasonable, as some files are created | |
212 | * with the default umask. This will make them world-readable but | |
213 | * writable only by the owner, which is ok for all files for which we | |
214 | * don't set the modes explicitly. | |
215 | */ | |
5260325f | 216 | umask(022); |
217 | ||
218 | /* Save our own name. */ | |
219 | av0 = av[0]; | |
220 | ||
221 | /* Initialize option structure to indicate that no values have been set. */ | |
222 | initialize_options(&options); | |
223 | ||
224 | /* Parse command-line arguments. */ | |
225 | host = NULL; | |
226 | ||
227 | /* If program name is not one of the standard names, use it as host name. */ | |
228 | if (strchr(av0, '/')) | |
229 | cp = strrchr(av0, '/') + 1; | |
230 | else | |
231 | cp = av0; | |
232 | if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 && | |
233 | strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0) | |
234 | host = cp; | |
235 | ||
236 | for (optind = 1; optind < ac; optind++) { | |
237 | if (av[optind][0] != '-') { | |
238 | if (host) | |
239 | break; | |
240 | if ((cp = strchr(av[optind], '@'))) { | |
48e671d5 | 241 | if(cp == av[optind]) |
242 | usage(); | |
5260325f | 243 | options.user = av[optind]; |
244 | *cp = '\0'; | |
245 | host = ++cp; | |
246 | } else | |
247 | host = av[optind]; | |
248 | continue; | |
249 | } | |
250 | opt = av[optind][1]; | |
251 | if (!opt) | |
252 | usage(); | |
253 | if (strchr("eilcpLRo", opt)) { /* options with arguments */ | |
254 | optarg = av[optind] + 2; | |
255 | if (strcmp(optarg, "") == 0) { | |
256 | if (optind >= ac - 1) | |
257 | usage(); | |
258 | optarg = av[++optind]; | |
259 | } | |
260 | } else { | |
261 | if (av[optind][2]) | |
262 | usage(); | |
263 | optarg = NULL; | |
264 | } | |
265 | switch (opt) { | |
48e671d5 | 266 | case '4': |
267 | IPv4or6 = AF_INET; | |
268 | break; | |
269 | ||
270 | case '6': | |
271 | IPv4or6 = AF_INET6; | |
272 | break; | |
273 | ||
5260325f | 274 | case 'n': |
275 | stdin_null_flag = 1; | |
276 | break; | |
277 | ||
278 | case 'f': | |
279 | fork_after_authentication_flag = 1; | |
280 | stdin_null_flag = 1; | |
281 | break; | |
282 | ||
283 | case 'x': | |
284 | options.forward_x11 = 0; | |
285 | break; | |
286 | ||
287 | case 'X': | |
288 | options.forward_x11 = 1; | |
289 | break; | |
290 | ||
291 | case 'g': | |
292 | options.gateway_ports = 1; | |
293 | break; | |
294 | ||
295 | case 'P': | |
296 | options.use_privileged_port = 0; | |
297 | break; | |
298 | ||
299 | case 'a': | |
300 | options.forward_agent = 0; | |
301 | break; | |
302 | #ifdef AFS | |
303 | case 'k': | |
304 | options.kerberos_tgt_passing = 0; | |
305 | options.afs_token_passing = 0; | |
306 | break; | |
307 | #endif | |
308 | case 'i': | |
309 | if (stat(optarg, &st) < 0) { | |
310 | fprintf(stderr, "Warning: Identity file %s does not exist.\n", | |
311 | optarg); | |
312 | break; | |
313 | } | |
314 | if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES) | |
315 | fatal("Too many identity files specified (max %d)", | |
316 | SSH_MAX_IDENTITY_FILES); | |
317 | options.identity_files[options.num_identity_files++] = | |
318 | xstrdup(optarg); | |
319 | break; | |
320 | ||
321 | case 't': | |
322 | tty_flag = 1; | |
323 | break; | |
324 | ||
325 | case 'v': | |
326 | case 'V': | |
327 | fprintf(stderr, "SSH Version %s, protocol version %d.%d.\n", | |
328 | SSH_VERSION, PROTOCOL_MAJOR, PROTOCOL_MINOR); | |
329 | fprintf(stderr, "Compiled with SSL.\n"); | |
330 | if (opt == 'V') | |
331 | exit(0); | |
332 | debug_flag = 1; | |
333 | options.log_level = SYSLOG_LEVEL_DEBUG; | |
334 | break; | |
335 | ||
336 | case 'q': | |
337 | options.log_level = SYSLOG_LEVEL_QUIET; | |
338 | break; | |
339 | ||
340 | case 'e': | |
341 | if (optarg[0] == '^' && optarg[2] == 0 && | |
342 | (unsigned char) optarg[1] >= 64 && (unsigned char) optarg[1] < 128) | |
343 | options.escape_char = (unsigned char) optarg[1] & 31; | |
344 | else if (strlen(optarg) == 1) | |
345 | options.escape_char = (unsigned char) optarg[0]; | |
346 | else if (strcmp(optarg, "none") == 0) | |
347 | options.escape_char = -2; | |
348 | else { | |
349 | fprintf(stderr, "Bad escape character '%s'.\n", optarg); | |
350 | exit(1); | |
351 | } | |
352 | break; | |
353 | ||
354 | case 'c': | |
355 | options.cipher = cipher_number(optarg); | |
356 | if (options.cipher == -1) { | |
357 | fprintf(stderr, "Unknown cipher type '%s'\n", optarg); | |
358 | exit(1); | |
359 | } | |
360 | break; | |
361 | ||
362 | case 'p': | |
363 | options.port = atoi(optarg); | |
5260325f | 364 | break; |
365 | ||
366 | case 'l': | |
367 | options.user = optarg; | |
368 | break; | |
369 | ||
370 | case 'R': | |
48e671d5 | 371 | if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf, |
372 | &fwd_host_port) != 3 && | |
373 | sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, | |
374 | &fwd_host_port) != 3) { | |
5260325f | 375 | fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); |
376 | usage(); | |
377 | /* NOTREACHED */ | |
378 | } | |
379 | add_remote_forward(&options, fwd_port, buf, fwd_host_port); | |
380 | break; | |
381 | ||
382 | case 'L': | |
48e671d5 | 383 | if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf, |
384 | &fwd_host_port) != 3 && | |
385 | sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, | |
386 | &fwd_host_port) != 3) { | |
5260325f | 387 | fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); |
388 | usage(); | |
389 | /* NOTREACHED */ | |
390 | } | |
391 | add_local_forward(&options, fwd_port, buf, fwd_host_port); | |
392 | break; | |
393 | ||
394 | case 'C': | |
395 | options.compression = 1; | |
396 | break; | |
397 | ||
398 | case 'o': | |
399 | dummy = 1; | |
400 | if (process_config_line(&options, host ? host : "", optarg, | |
401 | "command-line", 0, &dummy) != 0) | |
402 | exit(1); | |
403 | break; | |
404 | ||
405 | default: | |
406 | usage(); | |
407 | } | |
408 | } | |
409 | ||
410 | /* Check that we got a host name. */ | |
411 | if (!host) | |
8efc0c15 | 412 | usage(); |
5260325f | 413 | |
414 | /* check if RSA support exists */ | |
415 | if (rsa_alive() == 0) { | |
416 | fprintf(stderr, | |
417 | "%s: no RSA support in libssl and libcrypto. See ssl(8).\n", | |
418 | __progname); | |
419 | exit(1); | |
8efc0c15 | 420 | } |
5260325f | 421 | /* Initialize the command to execute on remote host. */ |
422 | buffer_init(&command); | |
423 | ||
aa3378df | 424 | /* |
425 | * Save the command to execute on the remote host in a buffer. There | |
426 | * is no limit on the length of the command, except by the maximum | |
427 | * packet size. Also sets the tty flag if there is no command. | |
428 | */ | |
5260325f | 429 | if (optind == ac) { |
430 | /* No command specified - execute shell on a tty. */ | |
431 | tty_flag = 1; | |
432 | } else { | |
433 | /* A command has been specified. Store it into the | |
434 | buffer. */ | |
435 | for (i = optind; i < ac; i++) { | |
436 | if (i > optind) | |
437 | buffer_append(&command, " ", 1); | |
438 | buffer_append(&command, av[i], strlen(av[i])); | |
439 | } | |
8efc0c15 | 440 | } |
5260325f | 441 | |
442 | /* Cannot fork to background if no command. */ | |
443 | if (fork_after_authentication_flag && buffer_len(&command) == 0) | |
444 | fatal("Cannot fork into background without a command to execute."); | |
445 | ||
446 | /* Allocate a tty by default if no command specified. */ | |
447 | if (buffer_len(&command) == 0) | |
448 | tty_flag = 1; | |
449 | ||
450 | /* Do not allocate a tty if stdin is not a tty. */ | |
451 | if (!isatty(fileno(stdin))) { | |
452 | if (tty_flag) | |
453 | fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n"); | |
454 | tty_flag = 0; | |
455 | } | |
456 | /* Get user data. */ | |
457 | pw = getpwuid(original_real_uid); | |
458 | if (!pw) { | |
459 | fprintf(stderr, "You don't exist, go away!\n"); | |
460 | exit(1); | |
461 | } | |
462 | /* Take a copy of the returned structure. */ | |
463 | memset(&pwcopy, 0, sizeof(pwcopy)); | |
464 | pwcopy.pw_name = xstrdup(pw->pw_name); | |
465 | pwcopy.pw_passwd = xstrdup(pw->pw_passwd); | |
466 | pwcopy.pw_uid = pw->pw_uid; | |
467 | pwcopy.pw_gid = pw->pw_gid; | |
468 | pwcopy.pw_dir = xstrdup(pw->pw_dir); | |
469 | pwcopy.pw_shell = xstrdup(pw->pw_shell); | |
470 | pw = &pwcopy; | |
471 | ||
472 | /* Initialize "log" output. Since we are the client all output | |
473 | actually goes to the terminal. */ | |
474 | log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); | |
475 | ||
476 | /* Read per-user configuration file. */ | |
477 | snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE); | |
478 | read_config_file(buf, host, &options); | |
479 | ||
480 | /* Read systemwide configuration file. */ | |
481 | read_config_file(HOST_CONFIG_FILE, host, &options); | |
482 | ||
483 | /* Fill configuration defaults. */ | |
484 | fill_default_options(&options); | |
485 | ||
486 | /* reinit */ | |
487 | log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); | |
488 | ||
489 | if (options.user == NULL) | |
490 | options.user = xstrdup(pw->pw_name); | |
491 | ||
492 | if (options.hostname != NULL) | |
493 | host = options.hostname; | |
494 | ||
495 | /* Find canonic host name. */ | |
496 | if (strchr(host, '.') == 0) { | |
48e671d5 | 497 | struct addrinfo hints; |
498 | struct addrinfo *ai = NULL; | |
499 | int errgai; | |
500 | memset(&hints, 0, sizeof(hints)); | |
c8d54615 | 501 | hints.ai_family = IPv4or6; |
48e671d5 | 502 | hints.ai_flags = AI_CANONNAME; |
503 | hints.ai_socktype = SOCK_STREAM; | |
504 | errgai = getaddrinfo(host, NULL, &hints, &ai); | |
505 | if (errgai == 0) { | |
506 | if (ai->ai_canonname != NULL) | |
507 | host = xstrdup(ai->ai_canonname); | |
508 | freeaddrinfo(ai); | |
8efc0c15 | 509 | } |
8efc0c15 | 510 | } |
5260325f | 511 | /* Disable rhosts authentication if not running as root. */ |
512 | if (original_effective_uid != 0 || !options.use_privileged_port) { | |
513 | options.rhosts_authentication = 0; | |
514 | options.rhosts_rsa_authentication = 0; | |
515 | } | |
aa3378df | 516 | /* |
517 | * If using rsh has been selected, exec it now (without trying | |
518 | * anything else). Note that we must release privileges first. | |
519 | */ | |
5260325f | 520 | if (options.use_rsh) { |
aa3378df | 521 | /* |
522 | * Restore our superuser privileges. This must be done | |
523 | * before permanently setting the uid. | |
524 | */ | |
5260325f | 525 | restore_uid(); |
526 | ||
527 | /* Switch to the original uid permanently. */ | |
528 | permanently_set_uid(original_real_uid); | |
529 | ||
530 | /* Execute rsh. */ | |
531 | rsh_connect(host, options.user, &command); | |
532 | fatal("rsh_connect returned"); | |
8efc0c15 | 533 | } |
5260325f | 534 | /* Restore our superuser privileges. */ |
535 | restore_uid(); | |
536 | ||
aa3378df | 537 | /* |
538 | * Open a connection to the remote host. This needs root privileges | |
539 | * if rhosts_{rsa_}authentication is enabled. | |
540 | */ | |
5260325f | 541 | |
542 | ok = ssh_connect(host, &hostaddr, options.port, | |
543 | options.connection_attempts, | |
544 | !options.rhosts_authentication && | |
545 | !options.rhosts_rsa_authentication, | |
546 | original_real_uid, | |
547 | options.proxy_command); | |
548 | ||
aa3378df | 549 | /* |
550 | * If we successfully made the connection, load the host private key | |
551 | * in case we will need it later for combined rsa-rhosts | |
552 | * authentication. This must be done before releasing extra | |
553 | * privileges, because the file is only readable by root. | |
554 | */ | |
5260325f | 555 | if (ok) { |
556 | host_private_key = RSA_new(); | |
557 | if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL)) | |
558 | host_private_key_loaded = 1; | |
559 | } | |
aa3378df | 560 | /* |
561 | * Get rid of any extra privileges that we may have. We will no | |
562 | * longer need them. Also, extra privileges could make it very hard | |
563 | * to read identity files and other non-world-readable files from the | |
564 | * user's home directory if it happens to be on a NFS volume where | |
565 | * root is mapped to nobody. | |
566 | */ | |
567 | ||
568 | /* | |
569 | * Note that some legacy systems need to postpone the following call | |
570 | * to permanently_set_uid() until the private hostkey is destroyed | |
571 | * with RSA_free(). Otherwise the calling user could ptrace() the | |
572 | * process, read the private hostkey and impersonate the host. | |
573 | * OpenBSD does not allow ptracing of setuid processes. | |
574 | */ | |
5260325f | 575 | permanently_set_uid(original_real_uid); |
576 | ||
aa3378df | 577 | /* |
578 | * Now that we are back to our own permissions, create ~/.ssh | |
579 | * directory if it doesn\'t already exist. | |
580 | */ | |
5260325f | 581 | snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR); |
582 | if (stat(buf, &st) < 0) | |
583 | if (mkdir(buf, 0755) < 0) | |
584 | error("Could not create directory '%.200s'.", buf); | |
585 | ||
586 | /* Check if the connection failed, and try "rsh" if appropriate. */ | |
587 | if (!ok) { | |
588 | if (options.port != 0) | |
57112b5a | 589 | log("Secure connection to %.100s on port %hu refused%.100s.", |
5260325f | 590 | host, options.port, |
591 | options.fallback_to_rsh ? "; reverting to insecure method" : ""); | |
592 | else | |
593 | log("Secure connection to %.100s refused%.100s.", host, | |
594 | options.fallback_to_rsh ? "; reverting to insecure method" : ""); | |
595 | ||
596 | if (options.fallback_to_rsh) { | |
597 | rsh_connect(host, options.user, &command); | |
598 | fatal("rsh_connect returned"); | |
599 | } | |
600 | exit(1); | |
8efc0c15 | 601 | } |
5260325f | 602 | /* Expand ~ in options.identity_files. */ |
603 | for (i = 0; i < options.num_identity_files; i++) | |
604 | options.identity_files[i] = | |
605 | tilde_expand_filename(options.identity_files[i], original_real_uid); | |
606 | ||
607 | /* Expand ~ in known host file names. */ | |
608 | options.system_hostfile = tilde_expand_filename(options.system_hostfile, | |
609 | original_real_uid); | |
610 | options.user_hostfile = tilde_expand_filename(options.user_hostfile, | |
611 | original_real_uid); | |
612 | ||
613 | /* Log into the remote system. This never returns if the login fails. */ | |
614 | ssh_login(host_private_key_loaded, host_private_key, | |
48e671d5 | 615 | host, (struct sockaddr *)&hostaddr, original_real_uid); |
5260325f | 616 | |
617 | /* We no longer need the host private key. Clear it now. */ | |
618 | if (host_private_key_loaded) | |
619 | RSA_free(host_private_key); /* Destroys contents safely */ | |
620 | ||
621 | /* Close connection cleanly after attack. */ | |
622 | cipher_attack_detected = packet_disconnect; | |
623 | ||
5260325f | 624 | /* Enable compression if requested. */ |
625 | if (options.compression) { | |
626 | debug("Requesting compression at level %d.", options.compression_level); | |
627 | ||
628 | if (options.compression_level < 1 || options.compression_level > 9) | |
629 | fatal("Compression level must be from 1 (fast) to 9 (slow, best)."); | |
630 | ||
631 | /* Send the request. */ | |
632 | packet_start(SSH_CMSG_REQUEST_COMPRESSION); | |
633 | packet_put_int(options.compression_level); | |
634 | packet_send(); | |
635 | packet_write_wait(); | |
636 | type = packet_read(&plen); | |
637 | if (type == SSH_SMSG_SUCCESS) | |
638 | packet_start_compression(options.compression_level); | |
639 | else if (type == SSH_SMSG_FAILURE) | |
640 | log("Warning: Remote host refused compression."); | |
641 | else | |
642 | packet_disconnect("Protocol error waiting for compression response."); | |
643 | } | |
644 | /* Allocate a pseudo tty if appropriate. */ | |
645 | if (tty_flag) { | |
646 | debug("Requesting pty."); | |
647 | ||
648 | /* Start the packet. */ | |
649 | packet_start(SSH_CMSG_REQUEST_PTY); | |
650 | ||
651 | /* Store TERM in the packet. There is no limit on the | |
652 | length of the string. */ | |
653 | cp = getenv("TERM"); | |
654 | if (!cp) | |
655 | cp = ""; | |
656 | packet_put_string(cp, strlen(cp)); | |
657 | ||
658 | /* Store window size in the packet. */ | |
659 | if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) | |
660 | memset(&ws, 0, sizeof(ws)); | |
661 | packet_put_int(ws.ws_row); | |
662 | packet_put_int(ws.ws_col); | |
663 | packet_put_int(ws.ws_xpixel); | |
664 | packet_put_int(ws.ws_ypixel); | |
665 | ||
666 | /* Store tty modes in the packet. */ | |
667 | tty_make_modes(fileno(stdin)); | |
668 | ||
669 | /* Send the packet, and wait for it to leave. */ | |
670 | packet_send(); | |
671 | packet_write_wait(); | |
672 | ||
673 | /* Read response from the server. */ | |
674 | type = packet_read(&plen); | |
675 | if (type == SSH_SMSG_SUCCESS) | |
676 | interactive = 1; | |
677 | else if (type == SSH_SMSG_FAILURE) | |
678 | log("Warning: Remote host failed or refused to allocate a pseudo tty."); | |
679 | else | |
680 | packet_disconnect("Protocol error waiting for pty request response."); | |
681 | } | |
682 | /* Request X11 forwarding if enabled and DISPLAY is set. */ | |
683 | if (options.forward_x11 && getenv("DISPLAY") != NULL) { | |
684 | char line[512], proto[512], data[512]; | |
685 | FILE *f; | |
686 | int forwarded = 0, got_data = 0, i; | |
8efc0c15 | 687 | |
688 | #ifdef XAUTH_PATH | |
5260325f | 689 | /* Try to get Xauthority information for the display. */ |
690 | snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null", | |
691 | XAUTH_PATH, getenv("DISPLAY")); | |
692 | f = popen(line, "r"); | |
693 | if (f && fgets(line, sizeof(line), f) && | |
694 | sscanf(line, "%*s %s %s", proto, data) == 2) | |
695 | got_data = 1; | |
696 | if (f) | |
697 | pclose(f); | |
8efc0c15 | 698 | #endif /* XAUTH_PATH */ |
aa3378df | 699 | /* |
700 | * If we didn't get authentication data, just make up some | |
701 | * data. The forwarding code will check the validity of the | |
702 | * response anyway, and substitute this data. The X11 | |
703 | * server, however, will ignore this fake data and use | |
704 | * whatever authentication mechanisms it was using otherwise | |
705 | * for the local connection. | |
706 | */ | |
5260325f | 707 | if (!got_data) { |
708 | u_int32_t rand = 0; | |
709 | ||
710 | strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto); | |
711 | for (i = 0; i < 16; i++) { | |
712 | if (i % 4 == 0) | |
713 | rand = arc4random(); | |
714 | snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff); | |
715 | rand >>= 8; | |
716 | } | |
717 | } | |
aa3378df | 718 | /* |
719 | * Got local authentication reasonable information. Request | |
720 | * forwarding with authentication spoofing. | |
721 | */ | |
5260325f | 722 | debug("Requesting X11 forwarding with authentication spoofing."); |
723 | x11_request_forwarding_with_spoofing(proto, data); | |
724 | ||
725 | /* Read response from the server. */ | |
726 | type = packet_read(&plen); | |
727 | if (type == SSH_SMSG_SUCCESS) { | |
728 | forwarded = 1; | |
729 | interactive = 1; | |
730 | } else if (type == SSH_SMSG_FAILURE) | |
731 | log("Warning: Remote host denied X11 forwarding."); | |
732 | else | |
733 | packet_disconnect("Protocol error waiting for X11 forwarding"); | |
734 | } | |
735 | /* Tell the packet module whether this is an interactive session. */ | |
736 | packet_set_interactive(interactive, options.keepalives); | |
737 | ||
738 | /* Clear agent forwarding if we don\'t have an agent. */ | |
739 | authfd = ssh_get_authentication_socket(); | |
740 | if (authfd < 0) | |
741 | options.forward_agent = 0; | |
742 | else | |
743 | ssh_close_authentication_socket(authfd); | |
744 | ||
745 | /* Request authentication agent forwarding if appropriate. */ | |
746 | if (options.forward_agent) { | |
747 | debug("Requesting authentication agent forwarding."); | |
748 | auth_request_forwarding(); | |
749 | ||
750 | /* Read response from the server. */ | |
751 | type = packet_read(&plen); | |
752 | packet_integrity_check(plen, 0, type); | |
753 | if (type != SSH_SMSG_SUCCESS) | |
754 | log("Warning: Remote host denied authentication agent forwarding."); | |
755 | } | |
756 | /* Initiate local TCP/IP port forwardings. */ | |
757 | for (i = 0; i < options.num_local_forwards; i++) { | |
758 | debug("Connections to local port %d forwarded to remote address %.200s:%d", | |
759 | options.local_forwards[i].port, | |
760 | options.local_forwards[i].host, | |
761 | options.local_forwards[i].host_port); | |
762 | channel_request_local_forwarding(options.local_forwards[i].port, | |
763 | options.local_forwards[i].host, | |
95f1eccc | 764 | options.local_forwards[i].host_port, |
765 | options.gateway_ports); | |
8efc0c15 | 766 | } |
767 | ||
5260325f | 768 | /* Initiate remote TCP/IP port forwardings. */ |
769 | for (i = 0; i < options.num_remote_forwards; i++) { | |
770 | debug("Connections to remote port %d forwarded to local address %.200s:%d", | |
771 | options.remote_forwards[i].port, | |
772 | options.remote_forwards[i].host, | |
773 | options.remote_forwards[i].host_port); | |
774 | channel_request_remote_forwarding(options.remote_forwards[i].port, | |
775 | options.remote_forwards[i].host, | |
776 | options.remote_forwards[i].host_port); | |
8efc0c15 | 777 | } |
5260325f | 778 | |
aa3378df | 779 | /* If requested, let ssh continue in the background. */ |
780 | if (fork_after_authentication_flag) | |
781 | if (daemon(1, 1) < 0) | |
782 | fatal("daemon() failed: %.200s", strerror(errno)); | |
783 | ||
784 | /* | |
785 | * If a command was specified on the command line, execute the | |
786 | * command now. Otherwise request the server to start a shell. | |
787 | */ | |
5260325f | 788 | if (buffer_len(&command) > 0) { |
789 | int len = buffer_len(&command); | |
790 | if (len > 900) | |
791 | len = 900; | |
792 | debug("Sending command: %.*s", len, buffer_ptr(&command)); | |
793 | packet_start(SSH_CMSG_EXEC_CMD); | |
794 | packet_put_string(buffer_ptr(&command), buffer_len(&command)); | |
795 | packet_send(); | |
796 | packet_write_wait(); | |
797 | } else { | |
798 | debug("Requesting shell."); | |
799 | packet_start(SSH_CMSG_EXEC_SHELL); | |
800 | packet_send(); | |
801 | packet_write_wait(); | |
802 | } | |
803 | ||
804 | /* Enter the interactive session. */ | |
805 | exit_status = client_loop(tty_flag, tty_flag ? options.escape_char : -1); | |
806 | ||
807 | /* Close the connection to the remote host. */ | |
808 | packet_close(); | |
809 | ||
810 | /* Exit with the status returned by the program on the remote side. */ | |
811 | exit(exit_status); | |
8efc0c15 | 812 | } |