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1 | /* | |
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 | * Ssh client program. This program can be used to log into a remote machine. | |
6 | * The software supports strong authentication, encryption, and forwarding | |
7 | * of X11, TCP/IP, and authentication connections. | |
8 | * | |
9 | * As far as I am concerned, the code I have written for this software | |
10 | * can be used freely for any purpose. Any derived versions of this | |
11 | * software must be clearly marked as such, and if the derived work is | |
12 | * incompatible with the protocol description in the RFC file, it must be | |
13 | * called by a name other than "ssh" or "Secure Shell". | |
14 | * | |
15 | * Copyright (c) 1999 Niels Provos. All rights reserved. | |
16 | * | |
17 | * Modified to work with SSL by Niels Provos <provos@citi.umich.edu> | |
18 | * in Canada (German citizen). | |
19 | * | |
20 | * Redistribution and use in source and binary forms, with or without | |
21 | * modification, are permitted provided that the following conditions | |
22 | * are met: | |
23 | * 1. Redistributions of source code must retain the above copyright | |
24 | * notice, this list of conditions and the following disclaimer. | |
25 | * 2. Redistributions in binary form must reproduce the above copyright | |
26 | * notice, this list of conditions and the following disclaimer in the | |
27 | * documentation and/or other materials provided with the distribution. | |
28 | * | |
29 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
30 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
31 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
32 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
33 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
34 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
35 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
36 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
37 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
38 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
39 | */ | |
40 | ||
41 | #include "includes.h" | |
42 | RCSID("$OpenBSD: ssh.c,v 1.114 2001/04/13 01:26:17 stevesk Exp $"); | |
43 | ||
44 | #include <openssl/evp.h> | |
45 | #include <openssl/err.h> | |
46 | ||
47 | #include "ssh.h" | |
48 | #include "ssh1.h" | |
49 | #include "ssh2.h" | |
50 | #include "compat.h" | |
51 | #include "cipher.h" | |
52 | #include "xmalloc.h" | |
53 | #include "packet.h" | |
54 | #include "buffer.h" | |
55 | #include "uidswap.h" | |
56 | #include "channels.h" | |
57 | #include "key.h" | |
58 | #include "authfd.h" | |
59 | #include "authfile.h" | |
60 | #include "pathnames.h" | |
61 | #include "clientloop.h" | |
62 | #include "log.h" | |
63 | #include "readconf.h" | |
64 | #include "sshconnect.h" | |
65 | #include "tildexpand.h" | |
66 | #include "dispatch.h" | |
67 | #include "misc.h" | |
68 | #include "kex.h" | |
69 | #include "mac.h" | |
70 | ||
71 | #ifdef HAVE___PROGNAME | |
72 | extern char *__progname; | |
73 | #else | |
74 | char *__progname; | |
75 | #endif | |
76 | ||
77 | /* Flag indicating whether IPv4 or IPv6. This can be set on the command line. | |
78 | Default value is AF_UNSPEC means both IPv4 and IPv6. */ | |
79 | #ifdef IPV4_DEFAULT | |
80 | int IPv4or6 = AF_INET; | |
81 | #else | |
82 | int IPv4or6 = AF_UNSPEC; | |
83 | #endif | |
84 | ||
85 | /* Flag indicating whether debug mode is on. This can be set on the command line. */ | |
86 | int debug_flag = 0; | |
87 | ||
88 | /* Flag indicating whether a tty should be allocated */ | |
89 | int tty_flag = 0; | |
90 | int no_tty_flag = 0; | |
91 | int force_tty_flag = 0; | |
92 | ||
93 | /* don't exec a shell */ | |
94 | int no_shell_flag = 0; | |
95 | ||
96 | /* | |
97 | * Flag indicating that nothing should be read from stdin. This can be set | |
98 | * on the command line. | |
99 | */ | |
100 | int stdin_null_flag = 0; | |
101 | ||
102 | /* | |
103 | * Flag indicating that ssh should fork after authentication. This is useful | |
104 | * so that the pasphrase can be entered manually, and then ssh goes to the | |
105 | * background. | |
106 | */ | |
107 | int fork_after_authentication_flag = 0; | |
108 | ||
109 | /* | |
110 | * General data structure for command line options and options configurable | |
111 | * in configuration files. See readconf.h. | |
112 | */ | |
113 | Options options; | |
114 | ||
115 | /* | |
116 | * Name of the host we are connecting to. This is the name given on the | |
117 | * command line, or the HostName specified for the user-supplied name in a | |
118 | * configuration file. | |
119 | */ | |
120 | char *host; | |
121 | ||
122 | /* socket address the host resolves to */ | |
123 | struct sockaddr_storage hostaddr; | |
124 | ||
125 | /* | |
126 | * Flag to indicate that we have received a window change signal which has | |
127 | * not yet been processed. This will cause a message indicating the new | |
128 | * window size to be sent to the server a little later. This is volatile | |
129 | * because this is updated in a signal handler. | |
130 | */ | |
131 | volatile int received_window_change_signal = 0; | |
132 | ||
133 | /* Private host keys. */ | |
134 | struct { | |
135 | Key **keys; | |
136 | int nkeys; | |
137 | } sensitive_data; | |
138 | ||
139 | /* Original real UID. */ | |
140 | uid_t original_real_uid; | |
141 | ||
142 | /* command to be executed */ | |
143 | Buffer command; | |
144 | ||
145 | /* Should we execute a command or invoke a subsystem? */ | |
146 | int subsystem_flag = 0; | |
147 | ||
148 | /* Prints a help message to the user. This function never returns. */ | |
149 | ||
150 | void | |
151 | usage(void) | |
152 | { | |
153 | fprintf(stderr, "Usage: %s [options] host [command]\n", __progname); | |
154 | fprintf(stderr, "Options:\n"); | |
155 | fprintf(stderr, " -l user Log in using this user name.\n"); | |
156 | fprintf(stderr, " -n Redirect input from " _PATH_DEVNULL ".\n"); | |
157 | fprintf(stderr, " -A Enable authentication agent forwarding.\n"); | |
158 | fprintf(stderr, " -a Disable authentication agent forwarding.\n"); | |
159 | #ifdef AFS | |
160 | fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n"); | |
161 | #endif /* AFS */ | |
162 | fprintf(stderr, " -X Enable X11 connection forwarding.\n"); | |
163 | fprintf(stderr, " -x Disable X11 connection forwarding.\n"); | |
164 | fprintf(stderr, " -i file Identity for public key authentication " | |
165 | "(default: ~/.ssh/identity)\n"); | |
166 | fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n"); | |
167 | fprintf(stderr, " -T Do not allocate a tty.\n"); | |
168 | fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); | |
169 | fprintf(stderr, " Multiple -v increases verbosity.\n"); | |
170 | fprintf(stderr, " -V Display version number only.\n"); | |
171 | fprintf(stderr, " -P Don't allocate a privileged port.\n"); | |
172 | fprintf(stderr, " -q Quiet; don't display any warning messages.\n"); | |
173 | fprintf(stderr, " -f Fork into background after authentication.\n"); | |
174 | fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n"); | |
175 | ||
176 | fprintf(stderr, " -c cipher Select encryption algorithm: " | |
177 | "``3des'', ``blowfish''\n"); | |
178 | fprintf(stderr, " -m macs Specify MAC algorithms for protocol version 2.\n"); | |
179 | fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n"); | |
180 | fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n"); | |
181 | fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n"); | |
182 | fprintf(stderr, " These cause %s to listen for connections on a port, and\n", __progname); | |
183 | fprintf(stderr, " forward them to the other side by connecting to host:port.\n"); | |
184 | fprintf(stderr, " -D port Dynamically forward local port to multiple remote addresses.\n"); | |
185 | fprintf(stderr, " Allows %s to act as an application-layer proxy.\n", | |
186 | __progname); | |
187 | fprintf(stderr, " Protocols supported: SOCKS4, SOCKS5, HTTPS\n"); | |
188 | fprintf(stderr, " -C Enable compression.\n"); | |
189 | fprintf(stderr, " -N Do not execute a shell or command.\n"); | |
190 | fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n"); | |
191 | fprintf(stderr, " -1 Force protocol version 1.\n"); | |
192 | fprintf(stderr, " -2 Force protocol version 2.\n"); | |
193 | fprintf(stderr, " -4 Use IPv4 only.\n"); | |
194 | fprintf(stderr, " -6 Use IPv6 only.\n"); | |
195 | fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n"); | |
196 | fprintf(stderr, " -s Invoke command (mandatory) as SSH2 subsystem.\n"); | |
197 | exit(1); | |
198 | } | |
199 | ||
200 | /* | |
201 | * Connects to the given host using rsh (or prints an error message and exits | |
202 | * if rsh is not available). This function never returns. | |
203 | */ | |
204 | void | |
205 | rsh_connect(char *host, char *user, Buffer * command) | |
206 | { | |
207 | char *args[10]; | |
208 | int i; | |
209 | ||
210 | log("Using rsh. WARNING: Connection will not be encrypted."); | |
211 | /* Build argument list for rsh. */ | |
212 | i = 0; | |
213 | args[i++] = _PATH_RSH; | |
214 | /* host may have to come after user on some systems */ | |
215 | args[i++] = host; | |
216 | if (user) { | |
217 | args[i++] = "-l"; | |
218 | args[i++] = user; | |
219 | } | |
220 | if (buffer_len(command) > 0) { | |
221 | buffer_append(command, "\0", 1); | |
222 | args[i++] = buffer_ptr(command); | |
223 | } | |
224 | args[i++] = NULL; | |
225 | if (debug_flag) { | |
226 | for (i = 0; args[i]; i++) { | |
227 | if (i != 0) | |
228 | fprintf(stderr, " "); | |
229 | fprintf(stderr, "%s", args[i]); | |
230 | } | |
231 | fprintf(stderr, "\n"); | |
232 | } | |
233 | execv(_PATH_RSH, args); | |
234 | perror(_PATH_RSH); | |
235 | exit(1); | |
236 | } | |
237 | ||
238 | int ssh_session(void); | |
239 | int ssh_session2(void); | |
240 | void load_public_identity_files(void); | |
241 | ||
242 | /* | |
243 | * Main program for the ssh client. | |
244 | */ | |
245 | int | |
246 | main(int ac, char **av) | |
247 | { | |
248 | int i, opt, optind, exit_status, ok; | |
249 | u_short fwd_port, fwd_host_port; | |
250 | char *optarg, *cp, buf[256]; | |
251 | struct stat st; | |
252 | struct passwd *pw; | |
253 | int dummy; | |
254 | uid_t original_effective_uid; | |
255 | ||
256 | __progname = get_progname(av[0]); | |
257 | init_rng(); | |
258 | ||
259 | /* | |
260 | * Save the original real uid. It will be needed later (uid-swapping | |
261 | * may clobber the real uid). | |
262 | */ | |
263 | original_real_uid = getuid(); | |
264 | original_effective_uid = geteuid(); | |
265 | ||
266 | #ifdef HAVE_SETRLIMIT | |
267 | /* If we are installed setuid root be careful to not drop core. */ | |
268 | if (original_real_uid != original_effective_uid) { | |
269 | struct rlimit rlim; | |
270 | rlim.rlim_cur = rlim.rlim_max = 0; | |
271 | if (setrlimit(RLIMIT_CORE, &rlim) < 0) | |
272 | fatal("setrlimit failed: %.100s", strerror(errno)); | |
273 | } | |
274 | #endif | |
275 | /* Get user data. */ | |
276 | pw = getpwuid(original_real_uid); | |
277 | if (!pw) { | |
278 | log("You don't exist, go away!"); | |
279 | exit(1); | |
280 | } | |
281 | /* Take a copy of the returned structure. */ | |
282 | pw = pwcopy(pw); | |
283 | ||
284 | /* | |
285 | * Use uid-swapping to give up root privileges for the duration of | |
286 | * option processing. We will re-instantiate the rights when we are | |
287 | * ready to create the privileged port, and will permanently drop | |
288 | * them when the port has been created (actually, when the connection | |
289 | * has been made, as we may need to create the port several times). | |
290 | */ | |
291 | temporarily_use_uid(pw); | |
292 | ||
293 | /* | |
294 | * Set our umask to something reasonable, as some files are created | |
295 | * with the default umask. This will make them world-readable but | |
296 | * writable only by the owner, which is ok for all files for which we | |
297 | * don't set the modes explicitly. | |
298 | */ | |
299 | umask(022); | |
300 | ||
301 | /* Initialize option structure to indicate that no values have been set. */ | |
302 | initialize_options(&options); | |
303 | ||
304 | /* Parse command-line arguments. */ | |
305 | host = NULL; | |
306 | ||
307 | for (optind = 1; optind < ac; optind++) { | |
308 | if (av[optind][0] != '-') { | |
309 | if (host) | |
310 | break; | |
311 | if ((cp = strchr(av[optind], '@'))) { | |
312 | if(cp == av[optind]) | |
313 | usage(); | |
314 | options.user = av[optind]; | |
315 | *cp = '\0'; | |
316 | host = ++cp; | |
317 | } else | |
318 | host = av[optind]; | |
319 | continue; | |
320 | } | |
321 | opt = av[optind][1]; | |
322 | if (!opt) | |
323 | usage(); | |
324 | if (strchr("eilcmpLRDo", opt)) { /* options with arguments */ | |
325 | optarg = av[optind] + 2; | |
326 | if (strcmp(optarg, "") == 0) { | |
327 | if (optind >= ac - 1) | |
328 | usage(); | |
329 | optarg = av[++optind]; | |
330 | } | |
331 | } else { | |
332 | if (av[optind][2]) | |
333 | usage(); | |
334 | optarg = NULL; | |
335 | } | |
336 | switch (opt) { | |
337 | case '1': | |
338 | options.protocol = SSH_PROTO_1; | |
339 | break; | |
340 | case '2': | |
341 | options.protocol = SSH_PROTO_2; | |
342 | break; | |
343 | case '4': | |
344 | IPv4or6 = AF_INET; | |
345 | break; | |
346 | case '6': | |
347 | IPv4or6 = AF_INET6; | |
348 | break; | |
349 | case 'n': | |
350 | stdin_null_flag = 1; | |
351 | break; | |
352 | case 'f': | |
353 | fork_after_authentication_flag = 1; | |
354 | stdin_null_flag = 1; | |
355 | break; | |
356 | case 'x': | |
357 | options.forward_x11 = 0; | |
358 | break; | |
359 | case 'X': | |
360 | options.forward_x11 = 1; | |
361 | break; | |
362 | case 'g': | |
363 | options.gateway_ports = 1; | |
364 | break; | |
365 | case 'P': | |
366 | options.use_privileged_port = 0; | |
367 | break; | |
368 | case 'a': | |
369 | options.forward_agent = 0; | |
370 | break; | |
371 | case 'A': | |
372 | options.forward_agent = 1; | |
373 | break; | |
374 | #ifdef AFS | |
375 | case 'k': | |
376 | options.kerberos_tgt_passing = 0; | |
377 | options.afs_token_passing = 0; | |
378 | break; | |
379 | #endif | |
380 | case 'i': | |
381 | if (stat(optarg, &st) < 0) { | |
382 | fprintf(stderr, "Warning: Identity file %s does not exist.\n", | |
383 | optarg); | |
384 | break; | |
385 | } | |
386 | if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES) | |
387 | fatal("Too many identity files specified (max %d)", | |
388 | SSH_MAX_IDENTITY_FILES); | |
389 | options.identity_files[options.num_identity_files++] = xstrdup(optarg); | |
390 | break; | |
391 | case 't': | |
392 | if (tty_flag) | |
393 | force_tty_flag = 1; | |
394 | tty_flag = 1; | |
395 | break; | |
396 | case 'v': | |
397 | if (0 == debug_flag) { | |
398 | debug_flag = 1; | |
399 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
400 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
401 | options.log_level++; | |
402 | break; | |
403 | } else { | |
404 | fatal("Too high debugging level."); | |
405 | } | |
406 | /* fallthrough */ | |
407 | case 'V': | |
408 | fprintf(stderr, | |
409 | "%s, SSH protocols %d.%d/%d.%d, OpenSSL 0x%8.8lx\n", | |
410 | SSH_VERSION, | |
411 | PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1, | |
412 | PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, | |
413 | SSLeay()); | |
414 | if (opt == 'V') | |
415 | exit(0); | |
416 | break; | |
417 | case 'q': | |
418 | options.log_level = SYSLOG_LEVEL_QUIET; | |
419 | break; | |
420 | case 'e': | |
421 | if (optarg[0] == '^' && optarg[2] == 0 && | |
422 | (u_char) optarg[1] >= 64 && (u_char) optarg[1] < 128) | |
423 | options.escape_char = (u_char) optarg[1] & 31; | |
424 | else if (strlen(optarg) == 1) | |
425 | options.escape_char = (u_char) optarg[0]; | |
426 | else if (strcmp(optarg, "none") == 0) | |
427 | options.escape_char = -2; | |
428 | else { | |
429 | fprintf(stderr, "Bad escape character '%s'.\n", optarg); | |
430 | exit(1); | |
431 | } | |
432 | break; | |
433 | case 'c': | |
434 | if (ciphers_valid(optarg)) { | |
435 | /* SSH2 only */ | |
436 | options.ciphers = xstrdup(optarg); | |
437 | options.cipher = SSH_CIPHER_ILLEGAL; | |
438 | } else { | |
439 | /* SSH1 only */ | |
440 | options.cipher = cipher_number(optarg); | |
441 | if (options.cipher == -1) { | |
442 | fprintf(stderr, "Unknown cipher type '%s'\n", optarg); | |
443 | exit(1); | |
444 | } | |
445 | if (options.cipher == SSH_CIPHER_3DES) { | |
446 | options.ciphers = "3des-cbc"; | |
447 | } else if (options.cipher == SSH_CIPHER_BLOWFISH) { | |
448 | options.ciphers = "blowfish-cbc"; | |
449 | } else { | |
450 | options.ciphers = (char *)-1; | |
451 | } | |
452 | } | |
453 | break; | |
454 | case 'm': | |
455 | if (mac_valid(optarg)) | |
456 | options.macs = xstrdup(optarg); | |
457 | else { | |
458 | fprintf(stderr, "Unknown mac type '%s'\n", optarg); | |
459 | exit(1); | |
460 | } | |
461 | break; | |
462 | case 'p': | |
463 | options.port = a2port(optarg); | |
464 | if (options.port == 0) { | |
465 | fprintf(stderr, "Bad port '%s'\n", optarg); | |
466 | exit(1); | |
467 | } | |
468 | break; | |
469 | case 'l': | |
470 | options.user = optarg; | |
471 | break; | |
472 | case 'R': | |
473 | if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf, | |
474 | &fwd_host_port) != 3 && | |
475 | sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, | |
476 | &fwd_host_port) != 3) { | |
477 | fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); | |
478 | usage(); | |
479 | /* NOTREACHED */ | |
480 | } | |
481 | add_remote_forward(&options, fwd_port, buf, fwd_host_port); | |
482 | break; | |
483 | case 'L': | |
484 | if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf, | |
485 | &fwd_host_port) != 3 && | |
486 | sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, | |
487 | &fwd_host_port) != 3) { | |
488 | fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); | |
489 | usage(); | |
490 | /* NOTREACHED */ | |
491 | } | |
492 | add_local_forward(&options, fwd_port, buf, fwd_host_port); | |
493 | break; | |
494 | ||
495 | case 'D': | |
496 | fwd_port = a2port(optarg); | |
497 | if (fwd_port == 0) { | |
498 | fprintf(stderr, "Bad dynamic port '%s'\n", optarg); | |
499 | exit(1); | |
500 | } | |
501 | add_local_forward(&options, fwd_port, "socks4", 0); | |
502 | break; | |
503 | ||
504 | case 'C': | |
505 | options.compression = 1; | |
506 | break; | |
507 | case 'N': | |
508 | no_shell_flag = 1; | |
509 | no_tty_flag = 1; | |
510 | break; | |
511 | case 'T': | |
512 | no_tty_flag = 1; | |
513 | break; | |
514 | case 'o': | |
515 | dummy = 1; | |
516 | if (process_config_line(&options, host ? host : "", optarg, | |
517 | "command-line", 0, &dummy) != 0) | |
518 | exit(1); | |
519 | break; | |
520 | case 's': | |
521 | subsystem_flag = 1; | |
522 | break; | |
523 | default: | |
524 | usage(); | |
525 | } | |
526 | } | |
527 | ||
528 | /* Check that we got a host name. */ | |
529 | if (!host) | |
530 | usage(); | |
531 | ||
532 | SSLeay_add_all_algorithms(); | |
533 | ERR_load_crypto_strings(); | |
534 | ||
535 | /* Initialize the command to execute on remote host. */ | |
536 | buffer_init(&command); | |
537 | ||
538 | /* | |
539 | * Save the command to execute on the remote host in a buffer. There | |
540 | * is no limit on the length of the command, except by the maximum | |
541 | * packet size. Also sets the tty flag if there is no command. | |
542 | */ | |
543 | if (optind == ac) { | |
544 | /* No command specified - execute shell on a tty. */ | |
545 | tty_flag = 1; | |
546 | if (subsystem_flag) { | |
547 | fprintf(stderr, "You must specify a subsystem to invoke.\n"); | |
548 | usage(); | |
549 | } | |
550 | } else { | |
551 | /* A command has been specified. Store it into the | |
552 | buffer. */ | |
553 | for (i = optind; i < ac; i++) { | |
554 | if (i > optind) | |
555 | buffer_append(&command, " ", 1); | |
556 | buffer_append(&command, av[i], strlen(av[i])); | |
557 | } | |
558 | } | |
559 | ||
560 | /* Cannot fork to background if no command. */ | |
561 | if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag) | |
562 | fatal("Cannot fork into background without a command to execute."); | |
563 | ||
564 | /* Allocate a tty by default if no command specified. */ | |
565 | if (buffer_len(&command) == 0) | |
566 | tty_flag = 1; | |
567 | ||
568 | /* Force no tty*/ | |
569 | if (no_tty_flag) | |
570 | tty_flag = 0; | |
571 | /* Do not allocate a tty if stdin is not a tty. */ | |
572 | if (!isatty(fileno(stdin)) && !force_tty_flag) { | |
573 | if (tty_flag) | |
574 | log("Pseudo-terminal will not be allocated because stdin is not a terminal."); | |
575 | tty_flag = 0; | |
576 | } | |
577 | ||
578 | /* | |
579 | * Initialize "log" output. Since we are the client all output | |
580 | * actually goes to stderr. | |
581 | */ | |
582 | log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level, | |
583 | SYSLOG_FACILITY_USER, 1); | |
584 | ||
585 | /* Read per-user configuration file. */ | |
586 | snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, _PATH_SSH_USER_CONFFILE); | |
587 | read_config_file(buf, host, &options); | |
588 | ||
589 | /* Read systemwide configuration file. */ | |
590 | read_config_file(_PATH_HOST_CONFIG_FILE, host, &options); | |
591 | ||
592 | /* Fill configuration defaults. */ | |
593 | fill_default_options(&options); | |
594 | ||
595 | /* reinit */ | |
596 | log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1); | |
597 | ||
598 | seed_rng(); | |
599 | ||
600 | if (options.user == NULL) | |
601 | options.user = xstrdup(pw->pw_name); | |
602 | ||
603 | if (options.hostname != NULL) | |
604 | host = options.hostname; | |
605 | ||
606 | /* Disable rhosts authentication if not running as root. */ | |
607 | #ifdef HAVE_CYGWIN | |
608 | /* Ignore uid if running under Windows */ | |
609 | if (!options.use_privileged_port) { | |
610 | #else | |
611 | if (original_effective_uid != 0 || !options.use_privileged_port) { | |
612 | #endif | |
613 | debug("Rhosts Authentication disabled, " | |
614 | "originating port will not be trusted."); | |
615 | options.rhosts_authentication = 0; | |
616 | } | |
617 | ||
618 | /* | |
619 | * If using rsh has been selected, exec it now (without trying | |
620 | * anything else). Note that we must release privileges first. | |
621 | */ | |
622 | if (options.use_rsh) { | |
623 | /* | |
624 | * Restore our superuser privileges. This must be done | |
625 | * before permanently setting the uid. | |
626 | */ | |
627 | restore_uid(); | |
628 | ||
629 | /* Switch to the original uid permanently. */ | |
630 | permanently_set_uid(pw); | |
631 | ||
632 | /* Execute rsh. */ | |
633 | rsh_connect(host, options.user, &command); | |
634 | fatal("rsh_connect returned"); | |
635 | } | |
636 | /* Restore our superuser privileges. */ | |
637 | restore_uid(); | |
638 | ||
639 | /* Open a connection to the remote host. */ | |
640 | ||
641 | ok = ssh_connect(host, &hostaddr, options.port, | |
642 | options.connection_attempts, | |
643 | original_effective_uid != 0 || !options.use_privileged_port, | |
644 | pw, options.proxy_command); | |
645 | ||
646 | /* | |
647 | * If we successfully made the connection, load the host private key | |
648 | * in case we will need it later for combined rsa-rhosts | |
649 | * authentication. This must be done before releasing extra | |
650 | * privileges, because the file is only readable by root. | |
651 | */ | |
652 | sensitive_data.nkeys = 0; | |
653 | sensitive_data.keys = NULL; | |
654 | if (ok && (options.rhosts_rsa_authentication || | |
655 | options.hostbased_authentication)) { | |
656 | sensitive_data.nkeys = 3; | |
657 | sensitive_data.keys = xmalloc(sensitive_data.nkeys*sizeof(Key)); | |
658 | sensitive_data.keys[0] = key_load_private_type(KEY_RSA1, | |
659 | _PATH_HOST_KEY_FILE, "", NULL); | |
660 | sensitive_data.keys[1] = key_load_private_type(KEY_DSA, | |
661 | _PATH_HOST_DSA_KEY_FILE, "", NULL); | |
662 | sensitive_data.keys[2] = key_load_private_type(KEY_RSA, | |
663 | _PATH_HOST_RSA_KEY_FILE, "", NULL); | |
664 | } | |
665 | /* | |
666 | * Get rid of any extra privileges that we may have. We will no | |
667 | * longer need them. Also, extra privileges could make it very hard | |
668 | * to read identity files and other non-world-readable files from the | |
669 | * user's home directory if it happens to be on a NFS volume where | |
670 | * root is mapped to nobody. | |
671 | */ | |
672 | ||
673 | /* | |
674 | * Note that some legacy systems need to postpone the following call | |
675 | * to permanently_set_uid() until the private hostkey is destroyed | |
676 | * with RSA_free(). Otherwise the calling user could ptrace() the | |
677 | * process, read the private hostkey and impersonate the host. | |
678 | * OpenBSD does not allow ptracing of setuid processes. | |
679 | */ | |
680 | permanently_set_uid(pw); | |
681 | ||
682 | /* | |
683 | * Now that we are back to our own permissions, create ~/.ssh | |
684 | * directory if it doesn\'t already exist. | |
685 | */ | |
686 | snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, _PATH_SSH_USER_DIR); | |
687 | if (stat(buf, &st) < 0) | |
688 | if (mkdir(buf, 0700) < 0) | |
689 | error("Could not create directory '%.200s'.", buf); | |
690 | ||
691 | /* Check if the connection failed, and try "rsh" if appropriate. */ | |
692 | if (!ok) { | |
693 | if (options.port != 0) | |
694 | log("Secure connection to %.100s on port %hu refused%.100s.", | |
695 | host, options.port, | |
696 | options.fallback_to_rsh ? "; reverting to insecure method" : ""); | |
697 | else | |
698 | log("Secure connection to %.100s refused%.100s.", host, | |
699 | options.fallback_to_rsh ? "; reverting to insecure method" : ""); | |
700 | ||
701 | if (options.fallback_to_rsh) { | |
702 | rsh_connect(host, options.user, &command); | |
703 | fatal("rsh_connect returned"); | |
704 | } | |
705 | exit(1); | |
706 | } | |
707 | /* load options.identity_files */ | |
708 | load_public_identity_files(); | |
709 | ||
710 | /* Expand ~ in known host file names. */ | |
711 | /* XXX mem-leaks: */ | |
712 | options.system_hostfile = | |
713 | tilde_expand_filename(options.system_hostfile, original_real_uid); | |
714 | options.user_hostfile = | |
715 | tilde_expand_filename(options.user_hostfile, original_real_uid); | |
716 | options.system_hostfile2 = | |
717 | tilde_expand_filename(options.system_hostfile2, original_real_uid); | |
718 | options.user_hostfile2 = | |
719 | tilde_expand_filename(options.user_hostfile2, original_real_uid); | |
720 | ||
721 | /* Log into the remote system. This never returns if the login fails. */ | |
722 | ssh_login(sensitive_data.keys, sensitive_data.nkeys, | |
723 | host, (struct sockaddr *)&hostaddr, pw); | |
724 | ||
725 | /* We no longer need the private host keys. Clear them now. */ | |
726 | if (sensitive_data.nkeys != 0) { | |
727 | for (i = 0; i < sensitive_data.nkeys; i++) { | |
728 | if (sensitive_data.keys[i] != NULL) { | |
729 | /* Destroys contents safely */ | |
730 | debug3("clear hostkey %d", i); | |
731 | key_free(sensitive_data.keys[i]); | |
732 | sensitive_data.keys[i] = NULL; | |
733 | } | |
734 | } | |
735 | xfree(sensitive_data.keys); | |
736 | } | |
737 | ||
738 | exit_status = compat20 ? ssh_session2() : ssh_session(); | |
739 | packet_close(); | |
740 | return exit_status; | |
741 | } | |
742 | ||
743 | void | |
744 | x11_get_proto(char *proto, int proto_len, char *data, int data_len) | |
745 | { | |
746 | char line[512]; | |
747 | FILE *f; | |
748 | int got_data = 0, i; | |
749 | ||
750 | if (options.xauth_location) { | |
751 | /* Try to get Xauthority information for the display. */ | |
752 | snprintf(line, sizeof line, "%.100s list %.200s 2>" _PATH_DEVNULL, | |
753 | options.xauth_location, getenv("DISPLAY")); | |
754 | f = popen(line, "r"); | |
755 | if (f && fgets(line, sizeof(line), f) && | |
756 | sscanf(line, "%*s %s %s", proto, data) == 2) | |
757 | got_data = 1; | |
758 | if (f) | |
759 | pclose(f); | |
760 | } | |
761 | /* | |
762 | * If we didn't get authentication data, just make up some | |
763 | * data. The forwarding code will check the validity of the | |
764 | * response anyway, and substitute this data. The X11 | |
765 | * server, however, will ignore this fake data and use | |
766 | * whatever authentication mechanisms it was using otherwise | |
767 | * for the local connection. | |
768 | */ | |
769 | if (!got_data) { | |
770 | u_int32_t rand = 0; | |
771 | ||
772 | strlcpy(proto, "MIT-MAGIC-COOKIE-1", proto_len); | |
773 | for (i = 0; i < 16; i++) { | |
774 | if (i % 4 == 0) | |
775 | rand = arc4random(); | |
776 | snprintf(data + 2 * i, data_len - 2 * i, "%02x", rand & 0xff); | |
777 | rand >>= 8; | |
778 | } | |
779 | } | |
780 | } | |
781 | ||
782 | void | |
783 | ssh_init_forwarding(void) | |
784 | { | |
785 | int success = 0; | |
786 | int i; | |
787 | ||
788 | /* Initiate local TCP/IP port forwardings. */ | |
789 | for (i = 0; i < options.num_local_forwards; i++) { | |
790 | debug("Connections to local port %d forwarded to remote address %.200s:%d", | |
791 | options.local_forwards[i].port, | |
792 | options.local_forwards[i].host, | |
793 | options.local_forwards[i].host_port); | |
794 | success += channel_request_local_forwarding( | |
795 | options.local_forwards[i].port, | |
796 | options.local_forwards[i].host, | |
797 | options.local_forwards[i].host_port, | |
798 | options.gateway_ports); | |
799 | } | |
800 | if (i > 0 && success == 0) | |
801 | error("Could not request local forwarding."); | |
802 | ||
803 | /* Initiate remote TCP/IP port forwardings. */ | |
804 | for (i = 0; i < options.num_remote_forwards; i++) { | |
805 | debug("Connections to remote port %d forwarded to local address %.200s:%d", | |
806 | options.remote_forwards[i].port, | |
807 | options.remote_forwards[i].host, | |
808 | options.remote_forwards[i].host_port); | |
809 | channel_request_remote_forwarding( | |
810 | options.remote_forwards[i].port, | |
811 | options.remote_forwards[i].host, | |
812 | options.remote_forwards[i].host_port); | |
813 | } | |
814 | } | |
815 | ||
816 | void | |
817 | check_agent_present(void) | |
818 | { | |
819 | if (options.forward_agent) { | |
820 | /* Clear agent forwarding if we don\'t have an agent. */ | |
821 | int authfd = ssh_get_authentication_socket(); | |
822 | if (authfd < 0) | |
823 | options.forward_agent = 0; | |
824 | else | |
825 | ssh_close_authentication_socket(authfd); | |
826 | } | |
827 | } | |
828 | ||
829 | int | |
830 | ssh_session(void) | |
831 | { | |
832 | int type; | |
833 | int plen; | |
834 | int interactive = 0; | |
835 | int have_tty = 0; | |
836 | struct winsize ws; | |
837 | char *cp; | |
838 | ||
839 | /* Enable compression if requested. */ | |
840 | if (options.compression) { | |
841 | debug("Requesting compression at level %d.", options.compression_level); | |
842 | ||
843 | if (options.compression_level < 1 || options.compression_level > 9) | |
844 | fatal("Compression level must be from 1 (fast) to 9 (slow, best)."); | |
845 | ||
846 | /* Send the request. */ | |
847 | packet_start(SSH_CMSG_REQUEST_COMPRESSION); | |
848 | packet_put_int(options.compression_level); | |
849 | packet_send(); | |
850 | packet_write_wait(); | |
851 | type = packet_read(&plen); | |
852 | if (type == SSH_SMSG_SUCCESS) | |
853 | packet_start_compression(options.compression_level); | |
854 | else if (type == SSH_SMSG_FAILURE) | |
855 | log("Warning: Remote host refused compression."); | |
856 | else | |
857 | packet_disconnect("Protocol error waiting for compression response."); | |
858 | } | |
859 | /* Allocate a pseudo tty if appropriate. */ | |
860 | if (tty_flag) { | |
861 | debug("Requesting pty."); | |
862 | ||
863 | /* Start the packet. */ | |
864 | packet_start(SSH_CMSG_REQUEST_PTY); | |
865 | ||
866 | /* Store TERM in the packet. There is no limit on the | |
867 | length of the string. */ | |
868 | cp = getenv("TERM"); | |
869 | if (!cp) | |
870 | cp = ""; | |
871 | packet_put_string(cp, strlen(cp)); | |
872 | ||
873 | /* Store window size in the packet. */ | |
874 | if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) | |
875 | memset(&ws, 0, sizeof(ws)); | |
876 | packet_put_int(ws.ws_row); | |
877 | packet_put_int(ws.ws_col); | |
878 | packet_put_int(ws.ws_xpixel); | |
879 | packet_put_int(ws.ws_ypixel); | |
880 | ||
881 | /* Store tty modes in the packet. */ | |
882 | tty_make_modes(fileno(stdin)); | |
883 | ||
884 | /* Send the packet, and wait for it to leave. */ | |
885 | packet_send(); | |
886 | packet_write_wait(); | |
887 | ||
888 | /* Read response from the server. */ | |
889 | type = packet_read(&plen); | |
890 | if (type == SSH_SMSG_SUCCESS) { | |
891 | interactive = 1; | |
892 | have_tty = 1; | |
893 | } else if (type == SSH_SMSG_FAILURE) | |
894 | log("Warning: Remote host failed or refused to allocate a pseudo tty."); | |
895 | else | |
896 | packet_disconnect("Protocol error waiting for pty request response."); | |
897 | } | |
898 | /* Request X11 forwarding if enabled and DISPLAY is set. */ | |
899 | if (options.forward_x11 && getenv("DISPLAY") != NULL) { | |
900 | char proto[512], data[512]; | |
901 | /* Get reasonable local authentication information. */ | |
902 | x11_get_proto(proto, sizeof proto, data, sizeof data); | |
903 | /* Request forwarding with authentication spoofing. */ | |
904 | debug("Requesting X11 forwarding with authentication spoofing."); | |
905 | x11_request_forwarding_with_spoofing(0, proto, data); | |
906 | ||
907 | /* Read response from the server. */ | |
908 | type = packet_read(&plen); | |
909 | if (type == SSH_SMSG_SUCCESS) { | |
910 | interactive = 1; | |
911 | } else if (type == SSH_SMSG_FAILURE) { | |
912 | log("Warning: Remote host denied X11 forwarding."); | |
913 | } else { | |
914 | packet_disconnect("Protocol error waiting for X11 forwarding"); | |
915 | } | |
916 | } | |
917 | /* Tell the packet module whether this is an interactive session. */ | |
918 | packet_set_interactive(interactive); | |
919 | ||
920 | /* Request authentication agent forwarding if appropriate. */ | |
921 | check_agent_present(); | |
922 | ||
923 | if (options.forward_agent) { | |
924 | debug("Requesting authentication agent forwarding."); | |
925 | auth_request_forwarding(); | |
926 | ||
927 | /* Read response from the server. */ | |
928 | type = packet_read(&plen); | |
929 | packet_integrity_check(plen, 0, type); | |
930 | if (type != SSH_SMSG_SUCCESS) | |
931 | log("Warning: Remote host denied authentication agent forwarding."); | |
932 | } | |
933 | ||
934 | /* Initiate port forwardings. */ | |
935 | ssh_init_forwarding(); | |
936 | ||
937 | /* If requested, let ssh continue in the background. */ | |
938 | if (fork_after_authentication_flag) | |
939 | if (daemon(1, 1) < 0) | |
940 | fatal("daemon() failed: %.200s", strerror(errno)); | |
941 | ||
942 | /* | |
943 | * If a command was specified on the command line, execute the | |
944 | * command now. Otherwise request the server to start a shell. | |
945 | */ | |
946 | if (buffer_len(&command) > 0) { | |
947 | int len = buffer_len(&command); | |
948 | if (len > 900) | |
949 | len = 900; | |
950 | debug("Sending command: %.*s", len, buffer_ptr(&command)); | |
951 | packet_start(SSH_CMSG_EXEC_CMD); | |
952 | packet_put_string(buffer_ptr(&command), buffer_len(&command)); | |
953 | packet_send(); | |
954 | packet_write_wait(); | |
955 | } else { | |
956 | debug("Requesting shell."); | |
957 | packet_start(SSH_CMSG_EXEC_SHELL); | |
958 | packet_send(); | |
959 | packet_write_wait(); | |
960 | } | |
961 | ||
962 | /* Enter the interactive session. */ | |
963 | return client_loop(have_tty, tty_flag ? options.escape_char : -1, 0); | |
964 | } | |
965 | ||
966 | void | |
967 | client_subsystem_reply(int type, int plen, void *ctxt) | |
968 | { | |
969 | int id, len; | |
970 | ||
971 | id = packet_get_int(); | |
972 | len = buffer_len(&command); | |
973 | if (len > 900) | |
974 | len = 900; | |
975 | packet_done(); | |
976 | if (type == SSH2_MSG_CHANNEL_FAILURE) | |
977 | fatal("Request for subsystem '%.*s' failed on channel %d", | |
978 | len, buffer_ptr(&command), id); | |
979 | } | |
980 | ||
981 | void | |
982 | ssh_session2_callback(int id, void *arg) | |
983 | { | |
984 | int len; | |
985 | int interactive = 0; | |
986 | ||
987 | debug("client_init id %d arg %ld", id, (long)arg); | |
988 | ||
989 | if (tty_flag) { | |
990 | struct winsize ws; | |
991 | char *cp; | |
992 | cp = getenv("TERM"); | |
993 | if (!cp) | |
994 | cp = ""; | |
995 | /* Store window size in the packet. */ | |
996 | if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) | |
997 | memset(&ws, 0, sizeof(ws)); | |
998 | ||
999 | channel_request_start(id, "pty-req", 0); | |
1000 | packet_put_cstring(cp); | |
1001 | packet_put_int(ws.ws_col); | |
1002 | packet_put_int(ws.ws_row); | |
1003 | packet_put_int(ws.ws_xpixel); | |
1004 | packet_put_int(ws.ws_ypixel); | |
1005 | packet_put_cstring(""); /* XXX: encode terminal modes */ | |
1006 | packet_send(); | |
1007 | interactive = 1; | |
1008 | /* XXX wait for reply */ | |
1009 | } | |
1010 | if (options.forward_x11 && | |
1011 | getenv("DISPLAY") != NULL) { | |
1012 | char proto[512], data[512]; | |
1013 | /* Get reasonable local authentication information. */ | |
1014 | x11_get_proto(proto, sizeof proto, data, sizeof data); | |
1015 | /* Request forwarding with authentication spoofing. */ | |
1016 | debug("Requesting X11 forwarding with authentication spoofing."); | |
1017 | x11_request_forwarding_with_spoofing(id, proto, data); | |
1018 | interactive = 1; | |
1019 | /* XXX wait for reply */ | |
1020 | } | |
1021 | ||
1022 | check_agent_present(); | |
1023 | if (options.forward_agent) { | |
1024 | debug("Requesting authentication agent forwarding."); | |
1025 | channel_request_start(id, "auth-agent-req@openssh.com", 0); | |
1026 | packet_send(); | |
1027 | } | |
1028 | ||
1029 | len = buffer_len(&command); | |
1030 | if (len > 0) { | |
1031 | if (len > 900) | |
1032 | len = 900; | |
1033 | if (subsystem_flag) { | |
1034 | debug("Sending subsystem: %.*s", len, buffer_ptr(&command)); | |
1035 | channel_request_start(id, "subsystem", /*want reply*/ 1); | |
1036 | /* register callback for reply */ | |
1037 | /* XXX we asume that client_loop has already been called */ | |
1038 | dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply); | |
1039 | dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply); | |
1040 | } else { | |
1041 | debug("Sending command: %.*s", len, buffer_ptr(&command)); | |
1042 | channel_request_start(id, "exec", 0); | |
1043 | } | |
1044 | packet_put_string(buffer_ptr(&command), buffer_len(&command)); | |
1045 | packet_send(); | |
1046 | } else { | |
1047 | channel_request(id, "shell", 0); | |
1048 | } | |
1049 | /* channel_callback(id, SSH2_MSG_OPEN_CONFIGMATION, client_init, 0); */ | |
1050 | ||
1051 | /* register different callback, etc. XXX */ | |
1052 | packet_set_interactive(interactive); | |
1053 | } | |
1054 | ||
1055 | int | |
1056 | ssh_session2_command(void) | |
1057 | { | |
1058 | int id, window, packetmax; | |
1059 | int in, out, err; | |
1060 | ||
1061 | if (stdin_null_flag) { | |
1062 | in = open(_PATH_DEVNULL, O_RDONLY); | |
1063 | } else { | |
1064 | in = dup(STDIN_FILENO); | |
1065 | } | |
1066 | out = dup(STDOUT_FILENO); | |
1067 | err = dup(STDERR_FILENO); | |
1068 | ||
1069 | if (in < 0 || out < 0 || err < 0) | |
1070 | fatal("dup() in/out/err failed"); | |
1071 | ||
1072 | /* enable nonblocking unless tty */ | |
1073 | if (!isatty(in)) | |
1074 | set_nonblock(in); | |
1075 | if (!isatty(out)) | |
1076 | set_nonblock(out); | |
1077 | if (!isatty(err)) | |
1078 | set_nonblock(err); | |
1079 | ||
1080 | window = CHAN_SES_WINDOW_DEFAULT; | |
1081 | packetmax = CHAN_SES_PACKET_DEFAULT; | |
1082 | if (!tty_flag) { | |
1083 | window *= 2; | |
1084 | packetmax *=2; | |
1085 | } | |
1086 | id = channel_new( | |
1087 | "session", SSH_CHANNEL_OPENING, in, out, err, | |
1088 | window, packetmax, CHAN_EXTENDED_WRITE, | |
1089 | xstrdup("client-session"), /*nonblock*/0); | |
1090 | ||
1091 | debug("channel_new: %d", id); | |
1092 | ||
1093 | channel_open(id); | |
1094 | channel_register_callback(id, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, | |
1095 | ssh_session2_callback, (void *)0); | |
1096 | ||
1097 | return id; | |
1098 | } | |
1099 | ||
1100 | int | |
1101 | ssh_session2(void) | |
1102 | { | |
1103 | int id; | |
1104 | ||
1105 | /* XXX should be pre-session */ | |
1106 | ssh_init_forwarding(); | |
1107 | ||
1108 | id = no_shell_flag ? -1 : ssh_session2_command(); | |
1109 | ||
1110 | /* If requested, let ssh continue in the background. */ | |
1111 | if (fork_after_authentication_flag) | |
1112 | if (daemon(1, 1) < 0) | |
1113 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1114 | ||
1115 | return client_loop(tty_flag, tty_flag ? options.escape_char : -1, id); | |
1116 | } | |
1117 | ||
1118 | void | |
1119 | load_public_identity_files(void) | |
1120 | { | |
1121 | char *filename; | |
1122 | Key *public; | |
1123 | int i; | |
1124 | ||
1125 | for (i = 0; i < options.num_identity_files; i++) { | |
1126 | filename = tilde_expand_filename(options.identity_files[i], | |
1127 | original_real_uid); | |
1128 | public = key_load_public(filename, NULL); | |
1129 | debug("identity file %s type %d", filename, | |
1130 | public ? public->type : -1); | |
1131 | xfree(options.identity_files[i]); | |
1132 | options.identity_files[i] = filename; | |
1133 | options.identity_keys[i] = public; | |
1134 | } | |
1135 | } |