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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 1.75 2000/11/30 07:02:35 markus Exp $"); | |
43 | ||
44 | #include <openssl/evp.h> | |
45 | #include <openssl/dsa.h> | |
46 | #include <openssl/rsa.h> | |
47 | #include <openssl/err.h> | |
48 | ||
49 | #include "xmalloc.h" | |
50 | #include "ssh.h" | |
51 | #include "packet.h" | |
52 | #include "buffer.h" | |
53 | #include "readconf.h" | |
54 | #include "uidswap.h" | |
55 | ||
56 | #include "ssh2.h" | |
57 | #include "compat.h" | |
58 | #include "channels.h" | |
59 | #include "key.h" | |
60 | #include "authfd.h" | |
61 | #include "authfile.h" | |
62 | ||
63 | #ifdef HAVE___PROGNAME | |
64 | extern char *__progname; | |
65 | #else | |
66 | char *__progname; | |
67 | #endif | |
68 | ||
69 | /* Flag indicating whether IPv4 or IPv6. This can be set on the command line. | |
70 | Default value is AF_UNSPEC means both IPv4 and IPv6. */ | |
71 | #ifdef IPV4_DEFAULT | |
72 | int IPv4or6 = AF_INET; | |
73 | #else | |
74 | int IPv4or6 = AF_UNSPEC; | |
75 | #endif | |
76 | ||
77 | /* Flag indicating whether debug mode is on. This can be set on the command line. */ | |
78 | int debug_flag = 0; | |
79 | ||
80 | /* Flag indicating whether a tty should be allocated */ | |
81 | int tty_flag = 0; | |
82 | ||
83 | /* don't exec a shell */ | |
84 | int no_shell_flag = 0; | |
85 | int no_tty_flag = 0; | |
86 | ||
87 | /* | |
88 | * Flag indicating that nothing should be read from stdin. This can be set | |
89 | * on the command line. | |
90 | */ | |
91 | int stdin_null_flag = 0; | |
92 | ||
93 | /* | |
94 | * Flag indicating that ssh should fork after authentication. This is useful | |
95 | * so that the pasphrase can be entered manually, and then ssh goes to the | |
96 | * background. | |
97 | */ | |
98 | int fork_after_authentication_flag = 0; | |
99 | ||
100 | /* | |
101 | * General data structure for command line options and options configurable | |
102 | * in configuration files. See readconf.h. | |
103 | */ | |
104 | Options options; | |
105 | ||
106 | /* | |
107 | * Name of the host we are connecting to. This is the name given on the | |
108 | * command line, or the HostName specified for the user-supplied name in a | |
109 | * configuration file. | |
110 | */ | |
111 | char *host; | |
112 | ||
113 | /* socket address the host resolves to */ | |
114 | struct sockaddr_storage hostaddr; | |
115 | ||
116 | /* | |
117 | * Flag to indicate that we have received a window change signal which has | |
118 | * not yet been processed. This will cause a message indicating the new | |
119 | * window size to be sent to the server a little later. This is volatile | |
120 | * because this is updated in a signal handler. | |
121 | */ | |
122 | volatile int received_window_change_signal = 0; | |
123 | ||
124 | /* Flag indicating whether we have a valid host private key loaded. */ | |
125 | int host_private_key_loaded = 0; | |
126 | ||
127 | /* Host private key. */ | |
128 | RSA *host_private_key = NULL; | |
129 | ||
130 | /* Original real UID. */ | |
131 | uid_t original_real_uid; | |
132 | ||
133 | /* command to be executed */ | |
134 | Buffer command; | |
135 | ||
136 | /* Prints a help message to the user. This function never returns. */ | |
137 | ||
138 | void | |
139 | usage() | |
140 | { | |
141 | fprintf(stderr, "Usage: %s [options] host [command]\n", __progname); | |
142 | fprintf(stderr, "Options:\n"); | |
143 | fprintf(stderr, " -l user Log in using this user name.\n"); | |
144 | fprintf(stderr, " -n Redirect input from /dev/null.\n"); | |
145 | fprintf(stderr, " -A Enable authentication agent forwarding.\n"); | |
146 | fprintf(stderr, " -a Disable authentication agent forwarding.\n"); | |
147 | #ifdef AFS | |
148 | fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n"); | |
149 | #endif /* AFS */ | |
150 | fprintf(stderr, " -X Enable X11 connection forwarding.\n"); | |
151 | fprintf(stderr, " -x Disable X11 connection forwarding.\n"); | |
152 | fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n"); | |
153 | fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n"); | |
154 | fprintf(stderr, " -T Do not allocate a tty.\n"); | |
155 | fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); | |
156 | fprintf(stderr, " Multiple -v increases verbosity.\n"); | |
157 | fprintf(stderr, " -V Display version number only.\n"); | |
158 | fprintf(stderr, " -P Don't allocate a privileged port.\n"); | |
159 | fprintf(stderr, " -q Quiet; don't display any warning messages.\n"); | |
160 | fprintf(stderr, " -f Fork into background after authentication.\n"); | |
161 | fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n"); | |
162 | ||
163 | fprintf(stderr, " -c cipher Select encryption algorithm: " | |
164 | "``3des'', " | |
165 | "``blowfish''\n"); | |
166 | fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n"); | |
167 | fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n"); | |
168 | fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n"); | |
169 | fprintf(stderr, " These cause %s to listen for connections on a port, and\n", __progname); | |
170 | fprintf(stderr, " forward them to the other side by connecting to host:port.\n"); | |
171 | fprintf(stderr, " -C Enable compression.\n"); | |
172 | fprintf(stderr, " -N Do not execute a shell or command.\n"); | |
173 | fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n"); | |
174 | fprintf(stderr, " -4 Use IPv4 only.\n"); | |
175 | fprintf(stderr, " -6 Use IPv6 only.\n"); | |
176 | fprintf(stderr, " -2 Force protocol version 2.\n"); | |
177 | fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n"); | |
178 | exit(1); | |
179 | } | |
180 | ||
181 | /* | |
182 | * Connects to the given host using rsh (or prints an error message and exits | |
183 | * if rsh is not available). This function never returns. | |
184 | */ | |
185 | void | |
186 | rsh_connect(char *host, char *user, Buffer * command) | |
187 | { | |
188 | char *args[10]; | |
189 | int i; | |
190 | ||
191 | log("Using rsh. WARNING: Connection will not be encrypted."); | |
192 | /* Build argument list for rsh. */ | |
193 | i = 0; | |
194 | args[i++] = _PATH_RSH; | |
195 | /* host may have to come after user on some systems */ | |
196 | args[i++] = host; | |
197 | if (user) { | |
198 | args[i++] = "-l"; | |
199 | args[i++] = user; | |
200 | } | |
201 | if (buffer_len(command) > 0) { | |
202 | buffer_append(command, "\0", 1); | |
203 | args[i++] = buffer_ptr(command); | |
204 | } | |
205 | args[i++] = NULL; | |
206 | if (debug_flag) { | |
207 | for (i = 0; args[i]; i++) { | |
208 | if (i != 0) | |
209 | fprintf(stderr, " "); | |
210 | fprintf(stderr, "%s", args[i]); | |
211 | } | |
212 | fprintf(stderr, "\n"); | |
213 | } | |
214 | execv(_PATH_RSH, args); | |
215 | perror(_PATH_RSH); | |
216 | exit(1); | |
217 | } | |
218 | ||
219 | int ssh_session(void); | |
220 | int ssh_session2(void); | |
221 | int guess_identity_file_type(const char *filename); | |
222 | ||
223 | /* | |
224 | * Main program for the ssh client. | |
225 | */ | |
226 | int | |
227 | main(int ac, char **av) | |
228 | { | |
229 | int i, opt, optind, exit_status, ok; | |
230 | u_short fwd_port, fwd_host_port; | |
231 | char *optarg, *cp, buf[256]; | |
232 | struct stat st; | |
233 | struct passwd *pw, pwcopy; | |
234 | int dummy; | |
235 | uid_t original_effective_uid; | |
236 | ||
237 | __progname = get_progname(av[0]); | |
238 | init_rng(); | |
239 | ||
240 | /* | |
241 | * Save the original real uid. It will be needed later (uid-swapping | |
242 | * may clobber the real uid). | |
243 | */ | |
244 | original_real_uid = getuid(); | |
245 | original_effective_uid = geteuid(); | |
246 | ||
247 | #ifdef HAVE_SETRLIMIT | |
248 | /* If we are installed setuid root be careful to not drop core. */ | |
249 | if (original_real_uid != original_effective_uid) { | |
250 | struct rlimit rlim; | |
251 | rlim.rlim_cur = rlim.rlim_max = 0; | |
252 | if (setrlimit(RLIMIT_CORE, &rlim) < 0) | |
253 | fatal("setrlimit failed: %.100s", strerror(errno)); | |
254 | } | |
255 | #endif | |
256 | /* | |
257 | * Use uid-swapping to give up root privileges for the duration of | |
258 | * option processing. We will re-instantiate the rights when we are | |
259 | * ready to create the privileged port, and will permanently drop | |
260 | * them when the port has been created (actually, when the connection | |
261 | * has been made, as we may need to create the port several times). | |
262 | */ | |
263 | temporarily_use_uid(original_real_uid); | |
264 | ||
265 | /* | |
266 | * Set our umask to something reasonable, as some files are created | |
267 | * with the default umask. This will make them world-readable but | |
268 | * writable only by the owner, which is ok for all files for which we | |
269 | * don't set the modes explicitly. | |
270 | */ | |
271 | umask(022); | |
272 | ||
273 | /* Initialize option structure to indicate that no values have been set. */ | |
274 | initialize_options(&options); | |
275 | ||
276 | /* Parse command-line arguments. */ | |
277 | host = NULL; | |
278 | ||
279 | /* If program name is not one of the standard names, use it as host name. */ | |
280 | cp = __progname; | |
281 | #ifdef HAVE_CYGWIN | |
282 | if (strcasecmp(cp, "rsh") && strcasecmp(cp, "ssh") && | |
283 | strcasecmp(cp, "rlogin") && strcasecmp(cp, "slogin") && | |
284 | strcasecmp(cp, "remsh") && | |
285 | strcasecmp(cp, "rsh.exe") && strcasecmp(cp, "ssh.exe") && | |
286 | strcasecmp(cp, "rlogin.exe") && strcasecmp(cp, "slogin.exe") && | |
287 | strcasecmp(cp, "remsh.exe")) | |
288 | #else | |
289 | if (strcmp(cp, "rsh") && strcmp(cp, "ssh") && strcmp(cp, "rlogin") && | |
290 | strcmp(cp, "slogin") && strcmp(cp, "remsh")) | |
291 | #endif | |
292 | host = cp; | |
293 | ||
294 | for (optind = 1; optind < ac; optind++) { | |
295 | if (av[optind][0] != '-') { | |
296 | if (host) | |
297 | break; | |
298 | if ((cp = strchr(av[optind], '@'))) { | |
299 | if(cp == av[optind]) | |
300 | usage(); | |
301 | options.user = av[optind]; | |
302 | *cp = '\0'; | |
303 | host = ++cp; | |
304 | } else | |
305 | host = av[optind]; | |
306 | continue; | |
307 | } | |
308 | opt = av[optind][1]; | |
309 | if (!opt) | |
310 | usage(); | |
311 | if (strchr("eilcpLRo", opt)) { /* options with arguments */ | |
312 | optarg = av[optind] + 2; | |
313 | if (strcmp(optarg, "") == 0) { | |
314 | if (optind >= ac - 1) | |
315 | usage(); | |
316 | optarg = av[++optind]; | |
317 | } | |
318 | } else { | |
319 | if (av[optind][2]) | |
320 | usage(); | |
321 | optarg = NULL; | |
322 | } | |
323 | switch (opt) { | |
324 | case '2': | |
325 | options.protocol = SSH_PROTO_2; | |
326 | break; | |
327 | case '4': | |
328 | IPv4or6 = AF_INET; | |
329 | break; | |
330 | case '6': | |
331 | IPv4or6 = AF_INET6; | |
332 | break; | |
333 | case 'n': | |
334 | stdin_null_flag = 1; | |
335 | break; | |
336 | case 'f': | |
337 | fork_after_authentication_flag = 1; | |
338 | stdin_null_flag = 1; | |
339 | break; | |
340 | case 'x': | |
341 | options.forward_x11 = 0; | |
342 | break; | |
343 | case 'X': | |
344 | options.forward_x11 = 1; | |
345 | break; | |
346 | case 'g': | |
347 | options.gateway_ports = 1; | |
348 | break; | |
349 | case 'P': | |
350 | options.use_privileged_port = 0; | |
351 | break; | |
352 | case 'a': | |
353 | options.forward_agent = 0; | |
354 | break; | |
355 | case 'A': | |
356 | options.forward_agent = 1; | |
357 | break; | |
358 | #ifdef AFS | |
359 | case 'k': | |
360 | options.kerberos_tgt_passing = 0; | |
361 | options.afs_token_passing = 0; | |
362 | break; | |
363 | #endif | |
364 | case 'i': | |
365 | if (stat(optarg, &st) < 0) { | |
366 | fprintf(stderr, "Warning: Identity file %s does not exist.\n", | |
367 | optarg); | |
368 | break; | |
369 | } | |
370 | if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES) | |
371 | fatal("Too many identity files specified (max %d)", | |
372 | SSH_MAX_IDENTITY_FILES); | |
373 | options.identity_files[options.num_identity_files++] = xstrdup(optarg); | |
374 | break; | |
375 | case 't': | |
376 | tty_flag = 1; | |
377 | break; | |
378 | case 'v': | |
379 | if (0 == debug_flag) { | |
380 | debug_flag = 1; | |
381 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
382 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
383 | options.log_level++; | |
384 | break; | |
385 | } else { | |
386 | fatal("Too high debugging level.\n"); | |
387 | } | |
388 | /* fallthrough */ | |
389 | case 'V': | |
390 | fprintf(stderr, "SSH Version %s, protocol versions %d.%d/%d.%d.\n", | |
391 | SSH_VERSION, | |
392 | PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1, | |
393 | PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2); | |
394 | fprintf(stderr, "Compiled with SSL (0x%8.8lx).\n", SSLeay()); | |
395 | if (opt == 'V') | |
396 | exit(0); | |
397 | break; | |
398 | case 'q': | |
399 | options.log_level = SYSLOG_LEVEL_QUIET; | |
400 | break; | |
401 | case 'e': | |
402 | if (optarg[0] == '^' && optarg[2] == 0 && | |
403 | (unsigned char) optarg[1] >= 64 && (unsigned char) optarg[1] < 128) | |
404 | options.escape_char = (unsigned char) optarg[1] & 31; | |
405 | else if (strlen(optarg) == 1) | |
406 | options.escape_char = (unsigned char) optarg[0]; | |
407 | else if (strcmp(optarg, "none") == 0) | |
408 | options.escape_char = -2; | |
409 | else { | |
410 | fprintf(stderr, "Bad escape character '%s'.\n", optarg); | |
411 | exit(1); | |
412 | } | |
413 | break; | |
414 | case 'c': | |
415 | if (ciphers_valid(optarg)) { | |
416 | /* SSH2 only */ | |
417 | options.ciphers = xstrdup(optarg); | |
418 | options.cipher = SSH_CIPHER_ILLEGAL; | |
419 | } else { | |
420 | /* SSH1 only */ | |
421 | options.cipher = cipher_number(optarg); | |
422 | if (options.cipher == -1) { | |
423 | fprintf(stderr, "Unknown cipher type '%s'\n", optarg); | |
424 | exit(1); | |
425 | } | |
426 | if (options.cipher == SSH_CIPHER_3DES) { | |
427 | options.ciphers = "3des-cbc"; | |
428 | } else if (options.cipher == SSH_CIPHER_BLOWFISH) { | |
429 | options.ciphers = "blowfish-cbc"; | |
430 | } else { | |
431 | options.ciphers = (char *)-1; | |
432 | } | |
433 | } | |
434 | break; | |
435 | case 'p': | |
436 | options.port = atoi(optarg); | |
437 | break; | |
438 | case 'l': | |
439 | options.user = optarg; | |
440 | break; | |
441 | case 'R': | |
442 | if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf, | |
443 | &fwd_host_port) != 3 && | |
444 | sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, | |
445 | &fwd_host_port) != 3) { | |
446 | fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); | |
447 | usage(); | |
448 | /* NOTREACHED */ | |
449 | } | |
450 | add_remote_forward(&options, fwd_port, buf, fwd_host_port); | |
451 | break; | |
452 | case 'L': | |
453 | if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf, | |
454 | &fwd_host_port) != 3 && | |
455 | sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, | |
456 | &fwd_host_port) != 3) { | |
457 | fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); | |
458 | usage(); | |
459 | /* NOTREACHED */ | |
460 | } | |
461 | add_local_forward(&options, fwd_port, buf, fwd_host_port); | |
462 | break; | |
463 | case 'C': | |
464 | options.compression = 1; | |
465 | break; | |
466 | case 'N': | |
467 | no_shell_flag = 1; | |
468 | no_tty_flag = 1; | |
469 | break; | |
470 | case 'T': | |
471 | no_tty_flag = 1; | |
472 | break; | |
473 | case 'o': | |
474 | dummy = 1; | |
475 | if (process_config_line(&options, host ? host : "", optarg, | |
476 | "command-line", 0, &dummy) != 0) | |
477 | exit(1); | |
478 | break; | |
479 | default: | |
480 | usage(); | |
481 | } | |
482 | } | |
483 | ||
484 | /* Check that we got a host name. */ | |
485 | if (!host) | |
486 | usage(); | |
487 | ||
488 | SSLeay_add_all_algorithms(); | |
489 | ERR_load_crypto_strings(); | |
490 | ||
491 | /* Initialize the command to execute on remote host. */ | |
492 | buffer_init(&command); | |
493 | ||
494 | /* | |
495 | * Save the command to execute on the remote host in a buffer. There | |
496 | * is no limit on the length of the command, except by the maximum | |
497 | * packet size. Also sets the tty flag if there is no command. | |
498 | */ | |
499 | if (optind == ac) { | |
500 | /* No command specified - execute shell on a tty. */ | |
501 | tty_flag = 1; | |
502 | } else { | |
503 | /* A command has been specified. Store it into the | |
504 | buffer. */ | |
505 | for (i = optind; i < ac; i++) { | |
506 | if (i > optind) | |
507 | buffer_append(&command, " ", 1); | |
508 | buffer_append(&command, av[i], strlen(av[i])); | |
509 | } | |
510 | } | |
511 | ||
512 | /* Cannot fork to background if no command. */ | |
513 | if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag) | |
514 | fatal("Cannot fork into background without a command to execute."); | |
515 | ||
516 | /* Allocate a tty by default if no command specified. */ | |
517 | if (buffer_len(&command) == 0) | |
518 | tty_flag = 1; | |
519 | ||
520 | /* Force no tty*/ | |
521 | if (no_tty_flag) | |
522 | tty_flag = 0; | |
523 | /* Do not allocate a tty if stdin is not a tty. */ | |
524 | if (!isatty(fileno(stdin))) { | |
525 | if (tty_flag) | |
526 | fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n"); | |
527 | tty_flag = 0; | |
528 | } | |
529 | ||
530 | /* Get user data. */ | |
531 | pw = getpwuid(original_real_uid); | |
532 | if (!pw) { | |
533 | fprintf(stderr, "You don't exist, go away!\n"); | |
534 | exit(1); | |
535 | } | |
536 | /* Take a copy of the returned structure. */ | |
537 | memset(&pwcopy, 0, sizeof(pwcopy)); | |
538 | pwcopy.pw_name = xstrdup(pw->pw_name); | |
539 | pwcopy.pw_passwd = xstrdup(pw->pw_passwd); | |
540 | pwcopy.pw_uid = pw->pw_uid; | |
541 | pwcopy.pw_gid = pw->pw_gid; | |
542 | #ifdef HAVE_PW_CLASS_IN_PASSWD | |
543 | pwcopy.pw_class = xstrdup(pw->pw_class); | |
544 | #endif | |
545 | pwcopy.pw_dir = xstrdup(pw->pw_dir); | |
546 | pwcopy.pw_shell = xstrdup(pw->pw_shell); | |
547 | pw = &pwcopy; | |
548 | ||
549 | /* Initialize "log" output. Since we are the client all output | |
550 | actually goes to the terminal. */ | |
551 | log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); | |
552 | ||
553 | /* Read per-user configuration file. */ | |
554 | snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE); | |
555 | read_config_file(buf, host, &options); | |
556 | ||
557 | /* Read systemwide configuration file. */ | |
558 | read_config_file(HOST_CONFIG_FILE, host, &options); | |
559 | ||
560 | /* Fill configuration defaults. */ | |
561 | fill_default_options(&options); | |
562 | ||
563 | /* reinit */ | |
564 | log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); | |
565 | ||
566 | if (options.user == NULL) | |
567 | options.user = xstrdup(pw->pw_name); | |
568 | ||
569 | if (options.hostname != NULL) | |
570 | host = options.hostname; | |
571 | ||
572 | /* Disable rhosts authentication if not running as root. */ | |
573 | #ifdef HAVE_CYGWIN | |
574 | /* Ignore uid if running under Windows */ | |
575 | if (!options.use_privileged_port) { | |
576 | #else | |
577 | if (original_effective_uid != 0 || !options.use_privileged_port) { | |
578 | debug("Rhosts Authentication methods disabled, " | |
579 | "originating port will not be trusted."); | |
580 | #endif | |
581 | options.rhosts_authentication = 0; | |
582 | options.rhosts_rsa_authentication = 0; | |
583 | } | |
584 | /* | |
585 | * If using rsh has been selected, exec it now (without trying | |
586 | * anything else). Note that we must release privileges first. | |
587 | */ | |
588 | if (options.use_rsh) { | |
589 | /* | |
590 | * Restore our superuser privileges. This must be done | |
591 | * before permanently setting the uid. | |
592 | */ | |
593 | restore_uid(); | |
594 | ||
595 | /* Switch to the original uid permanently. */ | |
596 | permanently_set_uid(original_real_uid); | |
597 | ||
598 | /* Execute rsh. */ | |
599 | rsh_connect(host, options.user, &command); | |
600 | fatal("rsh_connect returned"); | |
601 | } | |
602 | /* Restore our superuser privileges. */ | |
603 | restore_uid(); | |
604 | ||
605 | /* | |
606 | * Open a connection to the remote host. This needs root privileges | |
607 | * if rhosts_{rsa_}authentication is enabled. | |
608 | */ | |
609 | ||
610 | ok = ssh_connect(host, &hostaddr, options.port, | |
611 | options.connection_attempts, | |
612 | !options.rhosts_authentication && | |
613 | !options.rhosts_rsa_authentication, | |
614 | original_real_uid, | |
615 | options.proxy_command); | |
616 | ||
617 | /* | |
618 | * If we successfully made the connection, load the host private key | |
619 | * in case we will need it later for combined rsa-rhosts | |
620 | * authentication. This must be done before releasing extra | |
621 | * privileges, because the file is only readable by root. | |
622 | */ | |
623 | if (ok && (options.protocol & SSH_PROTO_1)) { | |
624 | Key k; | |
625 | host_private_key = RSA_new(); | |
626 | k.type = KEY_RSA1; | |
627 | k.rsa = host_private_key; | |
628 | if (load_private_key(HOST_KEY_FILE, "", &k, NULL)) | |
629 | host_private_key_loaded = 1; | |
630 | } | |
631 | /* | |
632 | * Get rid of any extra privileges that we may have. We will no | |
633 | * longer need them. Also, extra privileges could make it very hard | |
634 | * to read identity files and other non-world-readable files from the | |
635 | * user's home directory if it happens to be on a NFS volume where | |
636 | * root is mapped to nobody. | |
637 | */ | |
638 | ||
639 | /* | |
640 | * Note that some legacy systems need to postpone the following call | |
641 | * to permanently_set_uid() until the private hostkey is destroyed | |
642 | * with RSA_free(). Otherwise the calling user could ptrace() the | |
643 | * process, read the private hostkey and impersonate the host. | |
644 | * OpenBSD does not allow ptracing of setuid processes. | |
645 | */ | |
646 | permanently_set_uid(original_real_uid); | |
647 | ||
648 | /* | |
649 | * Now that we are back to our own permissions, create ~/.ssh | |
650 | * directory if it doesn\'t already exist. | |
651 | */ | |
652 | snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR); | |
653 | if (stat(buf, &st) < 0) | |
654 | if (mkdir(buf, 0700) < 0) | |
655 | error("Could not create directory '%.200s'.", buf); | |
656 | ||
657 | /* Check if the connection failed, and try "rsh" if appropriate. */ | |
658 | if (!ok) { | |
659 | if (options.port != 0) | |
660 | log("Secure connection to %.100s on port %hu refused%.100s.", | |
661 | host, options.port, | |
662 | options.fallback_to_rsh ? "; reverting to insecure method" : ""); | |
663 | else | |
664 | log("Secure connection to %.100s refused%.100s.", host, | |
665 | options.fallback_to_rsh ? "; reverting to insecure method" : ""); | |
666 | ||
667 | if (options.fallback_to_rsh) { | |
668 | rsh_connect(host, options.user, &command); | |
669 | fatal("rsh_connect returned"); | |
670 | } | |
671 | exit(1); | |
672 | } | |
673 | /* Expand ~ in options.identity_files, known host file names. */ | |
674 | /* XXX mem-leaks */ | |
675 | for (i = 0; i < options.num_identity_files; i++) { | |
676 | options.identity_files[i] = | |
677 | tilde_expand_filename(options.identity_files[i], original_real_uid); | |
678 | options.identity_files_type[i] = guess_identity_file_type(options.identity_files[i]); | |
679 | debug("identity file %s type %d", options.identity_files[i], | |
680 | options.identity_files_type[i]); | |
681 | } | |
682 | options.system_hostfile = | |
683 | tilde_expand_filename(options.system_hostfile, original_real_uid); | |
684 | options.user_hostfile = | |
685 | tilde_expand_filename(options.user_hostfile, original_real_uid); | |
686 | options.system_hostfile2 = | |
687 | tilde_expand_filename(options.system_hostfile2, original_real_uid); | |
688 | options.user_hostfile2 = | |
689 | tilde_expand_filename(options.user_hostfile2, original_real_uid); | |
690 | ||
691 | /* Log into the remote system. This never returns if the login fails. */ | |
692 | ssh_login(host_private_key_loaded, host_private_key, | |
693 | host, (struct sockaddr *)&hostaddr, original_real_uid); | |
694 | ||
695 | /* We no longer need the host private key. Clear it now. */ | |
696 | if (host_private_key_loaded) | |
697 | RSA_free(host_private_key); /* Destroys contents safely */ | |
698 | ||
699 | exit_status = compat20 ? ssh_session2() : ssh_session(); | |
700 | packet_close(); | |
701 | return exit_status; | |
702 | } | |
703 | ||
704 | void | |
705 | x11_get_proto(char *proto, int proto_len, char *data, int data_len) | |
706 | { | |
707 | char line[512]; | |
708 | FILE *f; | |
709 | int got_data = 0, i; | |
710 | ||
711 | if (options.xauth_location) { | |
712 | /* Try to get Xauthority information for the display. */ | |
713 | snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null", | |
714 | options.xauth_location, getenv("DISPLAY")); | |
715 | f = popen(line, "r"); | |
716 | if (f && fgets(line, sizeof(line), f) && | |
717 | sscanf(line, "%*s %s %s", proto, data) == 2) | |
718 | got_data = 1; | |
719 | if (f) | |
720 | pclose(f); | |
721 | } | |
722 | /* | |
723 | * If we didn't get authentication data, just make up some | |
724 | * data. The forwarding code will check the validity of the | |
725 | * response anyway, and substitute this data. The X11 | |
726 | * server, however, will ignore this fake data and use | |
727 | * whatever authentication mechanisms it was using otherwise | |
728 | * for the local connection. | |
729 | */ | |
730 | if (!got_data) { | |
731 | u_int32_t rand = 0; | |
732 | ||
733 | strlcpy(proto, "MIT-MAGIC-COOKIE-1", proto_len); | |
734 | for (i = 0; i < 16; i++) { | |
735 | if (i % 4 == 0) | |
736 | rand = arc4random(); | |
737 | snprintf(data + 2 * i, data_len - 2 * i, "%02x", rand & 0xff); | |
738 | rand >>= 8; | |
739 | } | |
740 | } | |
741 | } | |
742 | ||
743 | void | |
744 | ssh_init_forwarding(void) | |
745 | { | |
746 | int i; | |
747 | /* Initiate local TCP/IP port forwardings. */ | |
748 | for (i = 0; i < options.num_local_forwards; i++) { | |
749 | debug("Connections to local port %d forwarded to remote address %.200s:%d", | |
750 | options.local_forwards[i].port, | |
751 | options.local_forwards[i].host, | |
752 | options.local_forwards[i].host_port); | |
753 | channel_request_local_forwarding( | |
754 | options.local_forwards[i].port, | |
755 | options.local_forwards[i].host, | |
756 | options.local_forwards[i].host_port, | |
757 | options.gateway_ports); | |
758 | } | |
759 | ||
760 | /* Initiate remote TCP/IP port forwardings. */ | |
761 | for (i = 0; i < options.num_remote_forwards; i++) { | |
762 | debug("Connections to remote port %d forwarded to local address %.200s:%d", | |
763 | options.remote_forwards[i].port, | |
764 | options.remote_forwards[i].host, | |
765 | options.remote_forwards[i].host_port); | |
766 | channel_request_remote_forwarding( | |
767 | options.remote_forwards[i].port, | |
768 | options.remote_forwards[i].host, | |
769 | options.remote_forwards[i].host_port); | |
770 | } | |
771 | } | |
772 | ||
773 | void | |
774 | check_agent_present(void) | |
775 | { | |
776 | if (options.forward_agent) { | |
777 | /* Clear agent forwarding if we don\'t have an agent. */ | |
778 | int authfd = ssh_get_authentication_socket(); | |
779 | if (authfd < 0) | |
780 | options.forward_agent = 0; | |
781 | else | |
782 | ssh_close_authentication_socket(authfd); | |
783 | } | |
784 | } | |
785 | ||
786 | int | |
787 | ssh_session(void) | |
788 | { | |
789 | int type; | |
790 | int plen; | |
791 | int interactive = 0; | |
792 | int have_tty = 0; | |
793 | struct winsize ws; | |
794 | char *cp; | |
795 | ||
796 | /* Enable compression if requested. */ | |
797 | if (options.compression) { | |
798 | debug("Requesting compression at level %d.", options.compression_level); | |
799 | ||
800 | if (options.compression_level < 1 || options.compression_level > 9) | |
801 | fatal("Compression level must be from 1 (fast) to 9 (slow, best)."); | |
802 | ||
803 | /* Send the request. */ | |
804 | packet_start(SSH_CMSG_REQUEST_COMPRESSION); | |
805 | packet_put_int(options.compression_level); | |
806 | packet_send(); | |
807 | packet_write_wait(); | |
808 | type = packet_read(&plen); | |
809 | if (type == SSH_SMSG_SUCCESS) | |
810 | packet_start_compression(options.compression_level); | |
811 | else if (type == SSH_SMSG_FAILURE) | |
812 | log("Warning: Remote host refused compression."); | |
813 | else | |
814 | packet_disconnect("Protocol error waiting for compression response."); | |
815 | } | |
816 | /* Allocate a pseudo tty if appropriate. */ | |
817 | if (tty_flag) { | |
818 | debug("Requesting pty."); | |
819 | ||
820 | /* Start the packet. */ | |
821 | packet_start(SSH_CMSG_REQUEST_PTY); | |
822 | ||
823 | /* Store TERM in the packet. There is no limit on the | |
824 | length of the string. */ | |
825 | cp = getenv("TERM"); | |
826 | if (!cp) | |
827 | cp = ""; | |
828 | packet_put_string(cp, strlen(cp)); | |
829 | ||
830 | /* Store window size in the packet. */ | |
831 | if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) | |
832 | memset(&ws, 0, sizeof(ws)); | |
833 | packet_put_int(ws.ws_row); | |
834 | packet_put_int(ws.ws_col); | |
835 | packet_put_int(ws.ws_xpixel); | |
836 | packet_put_int(ws.ws_ypixel); | |
837 | ||
838 | /* Store tty modes in the packet. */ | |
839 | tty_make_modes(fileno(stdin)); | |
840 | ||
841 | /* Send the packet, and wait for it to leave. */ | |
842 | packet_send(); | |
843 | packet_write_wait(); | |
844 | ||
845 | /* Read response from the server. */ | |
846 | type = packet_read(&plen); | |
847 | if (type == SSH_SMSG_SUCCESS) { | |
848 | interactive = 1; | |
849 | have_tty = 1; | |
850 | } else if (type == SSH_SMSG_FAILURE) | |
851 | log("Warning: Remote host failed or refused to allocate a pseudo tty."); | |
852 | else | |
853 | packet_disconnect("Protocol error waiting for pty request response."); | |
854 | } | |
855 | /* Request X11 forwarding if enabled and DISPLAY is set. */ | |
856 | if (options.forward_x11 && getenv("DISPLAY") != NULL) { | |
857 | char proto[512], data[512]; | |
858 | /* Get reasonable local authentication information. */ | |
859 | x11_get_proto(proto, sizeof proto, data, sizeof data); | |
860 | /* Request forwarding with authentication spoofing. */ | |
861 | debug("Requesting X11 forwarding with authentication spoofing."); | |
862 | x11_request_forwarding_with_spoofing(0, proto, data); | |
863 | ||
864 | /* Read response from the server. */ | |
865 | type = packet_read(&plen); | |
866 | if (type == SSH_SMSG_SUCCESS) { | |
867 | interactive = 1; | |
868 | } else if (type == SSH_SMSG_FAILURE) { | |
869 | log("Warning: Remote host denied X11 forwarding."); | |
870 | } else { | |
871 | packet_disconnect("Protocol error waiting for X11 forwarding"); | |
872 | } | |
873 | } | |
874 | /* Tell the packet module whether this is an interactive session. */ | |
875 | packet_set_interactive(interactive, options.keepalives); | |
876 | ||
877 | ||
878 | /* Request authentication agent forwarding if appropriate. */ | |
879 | check_agent_present(); | |
880 | ||
881 | if (options.forward_agent) { | |
882 | debug("Requesting authentication agent forwarding."); | |
883 | auth_request_forwarding(); | |
884 | ||
885 | /* Read response from the server. */ | |
886 | type = packet_read(&plen); | |
887 | packet_integrity_check(plen, 0, type); | |
888 | if (type != SSH_SMSG_SUCCESS) | |
889 | log("Warning: Remote host denied authentication agent forwarding."); | |
890 | } | |
891 | ||
892 | /* Initiate port forwardings. */ | |
893 | ssh_init_forwarding(); | |
894 | ||
895 | /* If requested, let ssh continue in the background. */ | |
896 | if (fork_after_authentication_flag) | |
897 | if (daemon(1, 1) < 0) | |
898 | fatal("daemon() failed: %.200s", strerror(errno)); | |
899 | ||
900 | /* | |
901 | * If a command was specified on the command line, execute the | |
902 | * command now. Otherwise request the server to start a shell. | |
903 | */ | |
904 | if (buffer_len(&command) > 0) { | |
905 | int len = buffer_len(&command); | |
906 | if (len > 900) | |
907 | len = 900; | |
908 | debug("Sending command: %.*s", len, buffer_ptr(&command)); | |
909 | packet_start(SSH_CMSG_EXEC_CMD); | |
910 | packet_put_string(buffer_ptr(&command), buffer_len(&command)); | |
911 | packet_send(); | |
912 | packet_write_wait(); | |
913 | } else { | |
914 | debug("Requesting shell."); | |
915 | packet_start(SSH_CMSG_EXEC_SHELL); | |
916 | packet_send(); | |
917 | packet_write_wait(); | |
918 | } | |
919 | ||
920 | /* Enter the interactive session. */ | |
921 | return client_loop(have_tty, tty_flag ? options.escape_char : -1, 0); | |
922 | } | |
923 | ||
924 | extern void client_set_session_ident(int id); | |
925 | ||
926 | void | |
927 | ssh_session2_callback(int id, void *arg) | |
928 | { | |
929 | int len; | |
930 | debug("client_init id %d arg %d", id, (int)arg); | |
931 | ||
932 | if (no_shell_flag) | |
933 | goto done; | |
934 | ||
935 | if (tty_flag) { | |
936 | struct winsize ws; | |
937 | char *cp; | |
938 | cp = getenv("TERM"); | |
939 | if (!cp) | |
940 | cp = ""; | |
941 | /* Store window size in the packet. */ | |
942 | if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) | |
943 | memset(&ws, 0, sizeof(ws)); | |
944 | ||
945 | channel_request_start(id, "pty-req", 0); | |
946 | packet_put_cstring(cp); | |
947 | packet_put_int(ws.ws_col); | |
948 | packet_put_int(ws.ws_row); | |
949 | packet_put_int(ws.ws_xpixel); | |
950 | packet_put_int(ws.ws_ypixel); | |
951 | packet_put_cstring(""); /* XXX: encode terminal modes */ | |
952 | packet_send(); | |
953 | /* XXX wait for reply */ | |
954 | } | |
955 | if (options.forward_x11 && | |
956 | getenv("DISPLAY") != NULL) { | |
957 | char proto[512], data[512]; | |
958 | /* Get reasonable local authentication information. */ | |
959 | x11_get_proto(proto, sizeof proto, data, sizeof data); | |
960 | /* Request forwarding with authentication spoofing. */ | |
961 | debug("Requesting X11 forwarding with authentication spoofing."); | |
962 | x11_request_forwarding_with_spoofing(id, proto, data); | |
963 | /* XXX wait for reply */ | |
964 | } | |
965 | ||
966 | check_agent_present(); | |
967 | if (options.forward_agent) { | |
968 | debug("Requesting authentication agent forwarding."); | |
969 | channel_request_start(id, "auth-agent-req@openssh.com", 0); | |
970 | packet_send(); | |
971 | } | |
972 | ||
973 | len = buffer_len(&command); | |
974 | if (len > 0) { | |
975 | if (len > 900) | |
976 | len = 900; | |
977 | debug("Sending command: %.*s", len, buffer_ptr(&command)); | |
978 | channel_request_start(id, "exec", 0); | |
979 | packet_put_string(buffer_ptr(&command), len); | |
980 | packet_send(); | |
981 | } else { | |
982 | channel_request(id, "shell", 0); | |
983 | } | |
984 | /* channel_callback(id, SSH2_MSG_OPEN_CONFIGMATION, client_init, 0); */ | |
985 | done: | |
986 | /* register different callback, etc. XXX */ | |
987 | client_set_session_ident(id); | |
988 | } | |
989 | ||
990 | int | |
991 | ssh_session2(void) | |
992 | { | |
993 | int window, packetmax, id; | |
994 | int in, out, err; | |
995 | ||
996 | if (stdin_null_flag) { | |
997 | in = open("/dev/null", O_RDONLY); | |
998 | } else { | |
999 | in = dup(STDIN_FILENO); | |
1000 | } | |
1001 | out = dup(STDOUT_FILENO); | |
1002 | err = dup(STDERR_FILENO); | |
1003 | ||
1004 | if (in < 0 || out < 0 || err < 0) | |
1005 | fatal("dup() in/out/err failed"); | |
1006 | ||
1007 | /* enable nonblocking unless tty */ | |
1008 | if (!isatty(in)) | |
1009 | set_nonblock(in); | |
1010 | if (!isatty(out)) | |
1011 | set_nonblock(out); | |
1012 | if (!isatty(err)) | |
1013 | set_nonblock(err); | |
1014 | ||
1015 | /* XXX should be pre-session */ | |
1016 | ssh_init_forwarding(); | |
1017 | ||
1018 | /* If requested, let ssh continue in the background. */ | |
1019 | if (fork_after_authentication_flag) | |
1020 | if (daemon(1, 1) < 0) | |
1021 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1022 | ||
1023 | window = CHAN_SES_WINDOW_DEFAULT; | |
1024 | packetmax = CHAN_SES_PACKET_DEFAULT; | |
1025 | if (!tty_flag) { | |
1026 | window *= 2; | |
1027 | packetmax *=2; | |
1028 | } | |
1029 | id = channel_new( | |
1030 | "session", SSH_CHANNEL_OPENING, in, out, err, | |
1031 | window, packetmax, CHAN_EXTENDED_WRITE, | |
1032 | xstrdup("client-session"), /*nonblock*/0); | |
1033 | ||
1034 | channel_open(id); | |
1035 | channel_register_callback(id, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, | |
1036 | ssh_session2_callback, (void *)0); | |
1037 | ||
1038 | return client_loop(tty_flag, tty_flag ? options.escape_char : -1, id); | |
1039 | } | |
1040 | ||
1041 | int | |
1042 | guess_identity_file_type(const char *filename) | |
1043 | { | |
1044 | struct stat st; | |
1045 | Key *public; | |
1046 | int type = KEY_RSA1; /* default */ | |
1047 | ||
1048 | if (stat(filename, &st) < 0) { | |
1049 | /* ignore this key */ | |
1050 | return KEY_UNSPEC; | |
1051 | } | |
1052 | public = key_new(type); | |
1053 | if (!load_public_key(filename, public, NULL)) { | |
1054 | /* ok, so we will assume this is 'some' key */ | |
1055 | type = KEY_UNSPEC; | |
1056 | } | |
1057 | key_free(public); | |
1058 | return type; | |
1059 | } |