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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 | * 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 | */ | |
12 | ||
13 | #include "includes.h" | |
14 | RCSID("$OpenBSD: ssh.c,v 1.56 2000/06/20 01:39:44 markus Exp $"); | |
15 | ||
16 | #include <openssl/evp.h> | |
17 | #include <openssl/dsa.h> | |
18 | #include <openssl/rsa.h> | |
19 | ||
20 | #include "xmalloc.h" | |
21 | #include "ssh.h" | |
22 | #include "packet.h" | |
23 | #include "buffer.h" | |
24 | #include "authfd.h" | |
25 | #include "readconf.h" | |
26 | #include "uidswap.h" | |
27 | ||
28 | #include "ssh2.h" | |
29 | #include "compat.h" | |
30 | #include "channels.h" | |
31 | #include "key.h" | |
32 | #include "authfile.h" | |
33 | ||
34 | #ifdef HAVE___PROGNAME | |
35 | extern char *__progname; | |
36 | #else /* HAVE___PROGNAME */ | |
37 | static const char *__progname = "ssh"; | |
38 | #endif /* HAVE___PROGNAME */ | |
39 | ||
40 | /* Flag indicating whether IPv4 or IPv6. This can be set on the command line. | |
41 | Default value is AF_UNSPEC means both IPv4 and IPv6. */ | |
42 | #ifdef IPV4_DEFAULT | |
43 | int IPv4or6 = AF_INET; | |
44 | #else | |
45 | int IPv4or6 = AF_UNSPEC; | |
46 | #endif | |
47 | ||
48 | /* Flag indicating whether debug mode is on. This can be set on the command line. */ | |
49 | int debug_flag = 0; | |
50 | ||
51 | /* Flag indicating whether a tty should be allocated */ | |
52 | int tty_flag = 0; | |
53 | ||
54 | /* don't exec a shell */ | |
55 | int no_shell_flag = 0; | |
56 | int no_tty_flag = 0; | |
57 | ||
58 | /* | |
59 | * Flag indicating that nothing should be read from stdin. This can be set | |
60 | * on the command line. | |
61 | */ | |
62 | int stdin_null_flag = 0; | |
63 | ||
64 | /* | |
65 | * Flag indicating that ssh should fork after authentication. This is useful | |
66 | * so that the pasphrase can be entered manually, and then ssh goes to the | |
67 | * background. | |
68 | */ | |
69 | int fork_after_authentication_flag = 0; | |
70 | ||
71 | /* | |
72 | * General data structure for command line options and options configurable | |
73 | * in configuration files. See readconf.h. | |
74 | */ | |
75 | Options options; | |
76 | ||
77 | /* | |
78 | * Name of the host we are connecting to. This is the name given on the | |
79 | * command line, or the HostName specified for the user-supplied name in a | |
80 | * configuration file. | |
81 | */ | |
82 | char *host; | |
83 | ||
84 | /* socket address the host resolves to */ | |
85 | struct sockaddr_storage hostaddr; | |
86 | ||
87 | /* | |
88 | * Flag to indicate that we have received a window change signal which has | |
89 | * not yet been processed. This will cause a message indicating the new | |
90 | * window size to be sent to the server a little later. This is volatile | |
91 | * because this is updated in a signal handler. | |
92 | */ | |
93 | volatile int received_window_change_signal = 0; | |
94 | ||
95 | /* Value of argv[0] (set in the main program). */ | |
96 | char *av0; | |
97 | ||
98 | /* Flag indicating whether we have a valid host private key loaded. */ | |
99 | int host_private_key_loaded = 0; | |
100 | ||
101 | /* Host private key. */ | |
102 | RSA *host_private_key = NULL; | |
103 | ||
104 | /* Original real UID. */ | |
105 | uid_t original_real_uid; | |
106 | ||
107 | /* command to be executed */ | |
108 | Buffer command; | |
109 | ||
110 | /* Prints a help message to the user. This function never returns. */ | |
111 | ||
112 | void | |
113 | usage() | |
114 | { | |
115 | fprintf(stderr, "Usage: %s [options] host [command]\n", av0); | |
116 | fprintf(stderr, "Options:\n"); | |
117 | fprintf(stderr, " -l user Log in using this user name.\n"); | |
118 | fprintf(stderr, " -n Redirect input from /dev/null.\n"); | |
119 | fprintf(stderr, " -A Enable authentication agent forwarding.\n"); | |
120 | fprintf(stderr, " -a Disable authentication agent forwarding.\n"); | |
121 | #ifdef AFS | |
122 | fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n"); | |
123 | #endif /* AFS */ | |
124 | fprintf(stderr, " -X Enable X11 connection forwarding.\n"); | |
125 | fprintf(stderr, " -x Disable X11 connection forwarding.\n"); | |
126 | fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n"); | |
127 | fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n"); | |
128 | fprintf(stderr, " -T Do not allocate a tty.\n"); | |
129 | fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); | |
130 | fprintf(stderr, " -V Display version number only.\n"); | |
131 | fprintf(stderr, " -P Don't allocate a privileged port.\n"); | |
132 | fprintf(stderr, " -q Quiet; don't display any warning messages.\n"); | |
133 | fprintf(stderr, " -f Fork into background after authentication.\n"); | |
134 | fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n"); | |
135 | ||
136 | fprintf(stderr, " -c cipher Select encryption algorithm: " | |
137 | "``3des'', " | |
138 | "``blowfish''\n"); | |
139 | fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n"); | |
140 | fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n"); | |
141 | fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n"); | |
142 | fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0); | |
143 | fprintf(stderr, " forward them to the other side by connecting to host:port.\n"); | |
144 | fprintf(stderr, " -C Enable compression.\n"); | |
145 | fprintf(stderr, " -N Do not execute a shell or command.\n"); | |
146 | fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n"); | |
147 | fprintf(stderr, " -4 Use IPv4 only.\n"); | |
148 | fprintf(stderr, " -6 Use IPv6 only.\n"); | |
149 | fprintf(stderr, " -2 Force protocol version 2.\n"); | |
150 | fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n"); | |
151 | exit(1); | |
152 | } | |
153 | ||
154 | /* | |
155 | * Connects to the given host using rsh (or prints an error message and exits | |
156 | * if rsh is not available). This function never returns. | |
157 | */ | |
158 | void | |
159 | rsh_connect(char *host, char *user, Buffer * command) | |
160 | { | |
161 | char *args[10]; | |
162 | int i; | |
163 | ||
164 | log("Using rsh. WARNING: Connection will not be encrypted."); | |
165 | /* Build argument list for rsh. */ | |
166 | i = 0; | |
167 | args[i++] = _PATH_RSH; | |
168 | /* host may have to come after user on some systems */ | |
169 | args[i++] = host; | |
170 | if (user) { | |
171 | args[i++] = "-l"; | |
172 | args[i++] = user; | |
173 | } | |
174 | if (buffer_len(command) > 0) { | |
175 | buffer_append(command, "\0", 1); | |
176 | args[i++] = buffer_ptr(command); | |
177 | } | |
178 | args[i++] = NULL; | |
179 | if (debug_flag) { | |
180 | for (i = 0; args[i]; i++) { | |
181 | if (i != 0) | |
182 | fprintf(stderr, " "); | |
183 | fprintf(stderr, "%s", args[i]); | |
184 | } | |
185 | fprintf(stderr, "\n"); | |
186 | } | |
187 | execv(_PATH_RSH, args); | |
188 | perror(_PATH_RSH); | |
189 | exit(1); | |
190 | } | |
191 | ||
192 | int ssh_session(void); | |
193 | int ssh_session2(void); | |
194 | ||
195 | /* | |
196 | * Main program for the ssh client. | |
197 | */ | |
198 | int | |
199 | main(int ac, char **av) | |
200 | { | |
201 | int i, opt, optind, exit_status, ok; | |
202 | u_short fwd_port, fwd_host_port; | |
203 | char *optarg, *cp, buf[256]; | |
204 | struct stat st; | |
205 | struct passwd *pw, pwcopy; | |
206 | int dummy; | |
207 | uid_t original_effective_uid; | |
208 | ||
209 | init_rng(); | |
210 | ||
211 | /* | |
212 | * Save the original real uid. It will be needed later (uid-swapping | |
213 | * may clobber the real uid). | |
214 | */ | |
215 | original_real_uid = getuid(); | |
216 | original_effective_uid = geteuid(); | |
217 | ||
218 | /* If we are installed setuid root be careful to not drop core. */ | |
219 | if (original_real_uid != original_effective_uid) { | |
220 | struct rlimit rlim; | |
221 | rlim.rlim_cur = rlim.rlim_max = 0; | |
222 | if (setrlimit(RLIMIT_CORE, &rlim) < 0) | |
223 | fatal("setrlimit failed: %.100s", strerror(errno)); | |
224 | } | |
225 | /* | |
226 | * Use uid-swapping to give up root privileges for the duration of | |
227 | * option processing. We will re-instantiate the rights when we are | |
228 | * ready to create the privileged port, and will permanently drop | |
229 | * them when the port has been created (actually, when the connection | |
230 | * has been made, as we may need to create the port several times). | |
231 | */ | |
232 | temporarily_use_uid(original_real_uid); | |
233 | ||
234 | /* | |
235 | * Set our umask to something reasonable, as some files are created | |
236 | * with the default umask. This will make them world-readable but | |
237 | * writable only by the owner, which is ok for all files for which we | |
238 | * don't set the modes explicitly. | |
239 | */ | |
240 | umask(022); | |
241 | ||
242 | /* Save our own name. */ | |
243 | av0 = av[0]; | |
244 | ||
245 | /* Initialize option structure to indicate that no values have been set. */ | |
246 | initialize_options(&options); | |
247 | ||
248 | /* Parse command-line arguments. */ | |
249 | host = NULL; | |
250 | ||
251 | /* If program name is not one of the standard names, use it as host name. */ | |
252 | if (strchr(av0, '/')) | |
253 | cp = strrchr(av0, '/') + 1; | |
254 | else | |
255 | cp = av0; | |
256 | if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 && | |
257 | strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0) | |
258 | host = cp; | |
259 | ||
260 | for (optind = 1; optind < ac; optind++) { | |
261 | if (av[optind][0] != '-') { | |
262 | if (host) | |
263 | break; | |
264 | if ((cp = strchr(av[optind], '@'))) { | |
265 | if(cp == av[optind]) | |
266 | usage(); | |
267 | options.user = av[optind]; | |
268 | *cp = '\0'; | |
269 | host = ++cp; | |
270 | } else | |
271 | host = av[optind]; | |
272 | continue; | |
273 | } | |
274 | opt = av[optind][1]; | |
275 | if (!opt) | |
276 | usage(); | |
277 | if (strchr("eilcpLRo", opt)) { /* options with arguments */ | |
278 | optarg = av[optind] + 2; | |
279 | if (strcmp(optarg, "") == 0) { | |
280 | if (optind >= ac - 1) | |
281 | usage(); | |
282 | optarg = av[++optind]; | |
283 | } | |
284 | } else { | |
285 | if (av[optind][2]) | |
286 | usage(); | |
287 | optarg = NULL; | |
288 | } | |
289 | switch (opt) { | |
290 | case '2': | |
291 | options.protocol = SSH_PROTO_2; | |
292 | break; | |
293 | case '4': | |
294 | IPv4or6 = AF_INET; | |
295 | break; | |
296 | case '6': | |
297 | IPv4or6 = AF_INET6; | |
298 | break; | |
299 | case 'n': | |
300 | stdin_null_flag = 1; | |
301 | break; | |
302 | case 'f': | |
303 | fork_after_authentication_flag = 1; | |
304 | stdin_null_flag = 1; | |
305 | break; | |
306 | case 'x': | |
307 | options.forward_x11 = 0; | |
308 | break; | |
309 | case 'X': | |
310 | options.forward_x11 = 1; | |
311 | break; | |
312 | case 'g': | |
313 | options.gateway_ports = 1; | |
314 | break; | |
315 | case 'P': | |
316 | options.use_privileged_port = 0; | |
317 | break; | |
318 | case 'a': | |
319 | options.forward_agent = 0; | |
320 | break; | |
321 | case 'A': | |
322 | options.forward_agent = 1; | |
323 | break; | |
324 | #ifdef AFS | |
325 | case 'k': | |
326 | options.kerberos_tgt_passing = 0; | |
327 | options.afs_token_passing = 0; | |
328 | break; | |
329 | #endif | |
330 | case 'i': | |
331 | if (stat(optarg, &st) < 0) { | |
332 | fprintf(stderr, "Warning: Identity file %s does not exist.\n", | |
333 | optarg); | |
334 | break; | |
335 | } | |
336 | if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES) | |
337 | fatal("Too many identity files specified (max %d)", | |
338 | SSH_MAX_IDENTITY_FILES); | |
339 | options.identity_files[options.num_identity_files++] = | |
340 | xstrdup(optarg); | |
341 | break; | |
342 | case 't': | |
343 | tty_flag = 1; | |
344 | break; | |
345 | case 'v': | |
346 | case 'V': | |
347 | fprintf(stderr, "SSH Version %s, protocol versions %d.%d/%d.%d.\n", | |
348 | SSH_VERSION, | |
349 | PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1, | |
350 | PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2); | |
351 | fprintf(stderr, "Compiled with SSL (0x%8.8lx).\n", SSLeay()); | |
352 | if (opt == 'V') | |
353 | exit(0); | |
354 | debug_flag = 1; | |
355 | options.log_level = SYSLOG_LEVEL_DEBUG; | |
356 | break; | |
357 | case 'q': | |
358 | options.log_level = SYSLOG_LEVEL_QUIET; | |
359 | break; | |
360 | case 'e': | |
361 | if (optarg[0] == '^' && optarg[2] == 0 && | |
362 | (unsigned char) optarg[1] >= 64 && (unsigned char) optarg[1] < 128) | |
363 | options.escape_char = (unsigned char) optarg[1] & 31; | |
364 | else if (strlen(optarg) == 1) | |
365 | options.escape_char = (unsigned char) optarg[0]; | |
366 | else if (strcmp(optarg, "none") == 0) | |
367 | options.escape_char = -2; | |
368 | else { | |
369 | fprintf(stderr, "Bad escape character '%s'.\n", optarg); | |
370 | exit(1); | |
371 | } | |
372 | break; | |
373 | case 'c': | |
374 | if (ciphers_valid(optarg)) { | |
375 | /* SSH2 only */ | |
376 | options.ciphers = xstrdup(optarg); | |
377 | options.cipher = SSH_CIPHER_ILLEGAL; | |
378 | } else { | |
379 | /* SSH1 only */ | |
380 | options.cipher = cipher_number(optarg); | |
381 | if (options.cipher == -1) { | |
382 | fprintf(stderr, "Unknown cipher type '%s'\n", optarg); | |
383 | exit(1); | |
384 | } | |
385 | } | |
386 | break; | |
387 | case 'p': | |
388 | options.port = atoi(optarg); | |
389 | break; | |
390 | case 'l': | |
391 | options.user = optarg; | |
392 | break; | |
393 | case 'R': | |
394 | if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf, | |
395 | &fwd_host_port) != 3 && | |
396 | sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, | |
397 | &fwd_host_port) != 3) { | |
398 | fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); | |
399 | usage(); | |
400 | /* NOTREACHED */ | |
401 | } | |
402 | add_remote_forward(&options, fwd_port, buf, fwd_host_port); | |
403 | break; | |
404 | case 'L': | |
405 | if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf, | |
406 | &fwd_host_port) != 3 && | |
407 | sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, | |
408 | &fwd_host_port) != 3) { | |
409 | fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); | |
410 | usage(); | |
411 | /* NOTREACHED */ | |
412 | } | |
413 | add_local_forward(&options, fwd_port, buf, fwd_host_port); | |
414 | break; | |
415 | case 'C': | |
416 | options.compression = 1; | |
417 | break; | |
418 | case 'N': | |
419 | no_shell_flag = 1; | |
420 | no_tty_flag = 1; | |
421 | break; | |
422 | case 'T': | |
423 | no_tty_flag = 1; | |
424 | break; | |
425 | case 'o': | |
426 | dummy = 1; | |
427 | if (process_config_line(&options, host ? host : "", optarg, | |
428 | "command-line", 0, &dummy) != 0) | |
429 | exit(1); | |
430 | break; | |
431 | default: | |
432 | usage(); | |
433 | } | |
434 | } | |
435 | ||
436 | /* Check that we got a host name. */ | |
437 | if (!host) | |
438 | usage(); | |
439 | ||
440 | /* Initialize the command to execute on remote host. */ | |
441 | buffer_init(&command); | |
442 | ||
443 | SSLeay_add_all_algorithms(); | |
444 | ||
445 | /* | |
446 | * Save the command to execute on the remote host in a buffer. There | |
447 | * is no limit on the length of the command, except by the maximum | |
448 | * packet size. Also sets the tty flag if there is no command. | |
449 | */ | |
450 | if (optind == ac) { | |
451 | /* No command specified - execute shell on a tty. */ | |
452 | tty_flag = 1; | |
453 | } else { | |
454 | /* A command has been specified. Store it into the | |
455 | buffer. */ | |
456 | for (i = optind; i < ac; i++) { | |
457 | if (i > optind) | |
458 | buffer_append(&command, " ", 1); | |
459 | buffer_append(&command, av[i], strlen(av[i])); | |
460 | } | |
461 | } | |
462 | ||
463 | /* Cannot fork to background if no command. */ | |
464 | if (fork_after_authentication_flag && buffer_len(&command) == 0) | |
465 | fatal("Cannot fork into background without a command to execute."); | |
466 | ||
467 | /* Allocate a tty by default if no command specified. */ | |
468 | if (buffer_len(&command) == 0) | |
469 | tty_flag = 1; | |
470 | ||
471 | /* Do not allocate a tty if stdin is not a tty. */ | |
472 | if (!isatty(fileno(stdin))) { | |
473 | if (tty_flag) | |
474 | fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n"); | |
475 | tty_flag = 0; | |
476 | } | |
477 | /* force */ | |
478 | if (no_tty_flag) | |
479 | tty_flag = 0; | |
480 | ||
481 | /* Get user data. */ | |
482 | pw = getpwuid(original_real_uid); | |
483 | if (!pw) { | |
484 | fprintf(stderr, "You don't exist, go away!\n"); | |
485 | exit(1); | |
486 | } | |
487 | /* Take a copy of the returned structure. */ | |
488 | memset(&pwcopy, 0, sizeof(pwcopy)); | |
489 | pwcopy.pw_name = xstrdup(pw->pw_name); | |
490 | pwcopy.pw_passwd = xstrdup(pw->pw_passwd); | |
491 | pwcopy.pw_uid = pw->pw_uid; | |
492 | pwcopy.pw_gid = pw->pw_gid; | |
493 | pwcopy.pw_dir = xstrdup(pw->pw_dir); | |
494 | pwcopy.pw_shell = xstrdup(pw->pw_shell); | |
495 | pw = &pwcopy; | |
496 | ||
497 | /* Initialize "log" output. Since we are the client all output | |
498 | actually goes to the terminal. */ | |
499 | log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); | |
500 | ||
501 | /* Read per-user configuration file. */ | |
502 | snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE); | |
503 | read_config_file(buf, host, &options); | |
504 | ||
505 | /* Read systemwide configuration file. */ | |
506 | read_config_file(HOST_CONFIG_FILE, host, &options); | |
507 | ||
508 | /* Fill configuration defaults. */ | |
509 | fill_default_options(&options); | |
510 | ||
511 | /* reinit */ | |
512 | log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); | |
513 | ||
514 | /* check if RSA support exists */ | |
515 | if ((options.protocol & SSH_PROTO_1) && | |
516 | rsa_alive() == 0) { | |
517 | log("%s: no RSA support in libssl and libcrypto. See ssl(8).", | |
518 | __progname); | |
519 | log("Disabling protocol version 1"); | |
520 | options.protocol &= ~ (SSH_PROTO_1|SSH_PROTO_1_PREFERRED); | |
521 | } | |
522 | if (! options.protocol & (SSH_PROTO_1|SSH_PROTO_2)) { | |
523 | fprintf(stderr, "%s: No protocol version available.\n", | |
524 | __progname); | |
525 | exit(1); | |
526 | } | |
527 | ||
528 | if (options.user == NULL) | |
529 | options.user = xstrdup(pw->pw_name); | |
530 | ||
531 | if (options.hostname != NULL) | |
532 | host = options.hostname; | |
533 | ||
534 | /* Find canonic host name. */ | |
535 | if (strchr(host, '.') == 0) { | |
536 | struct addrinfo hints; | |
537 | struct addrinfo *ai = NULL; | |
538 | int errgai; | |
539 | memset(&hints, 0, sizeof(hints)); | |
540 | hints.ai_family = IPv4or6; | |
541 | hints.ai_flags = AI_CANONNAME; | |
542 | hints.ai_socktype = SOCK_STREAM; | |
543 | errgai = getaddrinfo(host, NULL, &hints, &ai); | |
544 | if (errgai == 0) { | |
545 | if (ai->ai_canonname != NULL) | |
546 | host = xstrdup(ai->ai_canonname); | |
547 | freeaddrinfo(ai); | |
548 | } | |
549 | } | |
550 | /* Disable rhosts authentication if not running as root. */ | |
551 | if (original_effective_uid != 0 || !options.use_privileged_port) { | |
552 | options.rhosts_authentication = 0; | |
553 | options.rhosts_rsa_authentication = 0; | |
554 | } | |
555 | /* | |
556 | * If using rsh has been selected, exec it now (without trying | |
557 | * anything else). Note that we must release privileges first. | |
558 | */ | |
559 | if (options.use_rsh) { | |
560 | /* | |
561 | * Restore our superuser privileges. This must be done | |
562 | * before permanently setting the uid. | |
563 | */ | |
564 | restore_uid(); | |
565 | ||
566 | /* Switch to the original uid permanently. */ | |
567 | permanently_set_uid(original_real_uid); | |
568 | ||
569 | /* Execute rsh. */ | |
570 | rsh_connect(host, options.user, &command); | |
571 | fatal("rsh_connect returned"); | |
572 | } | |
573 | /* Restore our superuser privileges. */ | |
574 | restore_uid(); | |
575 | ||
576 | /* | |
577 | * Open a connection to the remote host. This needs root privileges | |
578 | * if rhosts_{rsa_}authentication is enabled. | |
579 | */ | |
580 | ||
581 | ok = ssh_connect(host, &hostaddr, options.port, | |
582 | options.connection_attempts, | |
583 | !options.rhosts_authentication && | |
584 | !options.rhosts_rsa_authentication, | |
585 | original_real_uid, | |
586 | options.proxy_command); | |
587 | ||
588 | /* | |
589 | * If we successfully made the connection, load the host private key | |
590 | * in case we will need it later for combined rsa-rhosts | |
591 | * authentication. This must be done before releasing extra | |
592 | * privileges, because the file is only readable by root. | |
593 | */ | |
594 | if (ok && (options.protocol & SSH_PROTO_1)) { | |
595 | Key k; | |
596 | host_private_key = RSA_new(); | |
597 | k.type = KEY_RSA; | |
598 | k.rsa = host_private_key; | |
599 | if (load_private_key(HOST_KEY_FILE, "", &k, NULL)) | |
600 | host_private_key_loaded = 1; | |
601 | } | |
602 | /* | |
603 | * Get rid of any extra privileges that we may have. We will no | |
604 | * longer need them. Also, extra privileges could make it very hard | |
605 | * to read identity files and other non-world-readable files from the | |
606 | * user's home directory if it happens to be on a NFS volume where | |
607 | * root is mapped to nobody. | |
608 | */ | |
609 | ||
610 | /* | |
611 | * Note that some legacy systems need to postpone the following call | |
612 | * to permanently_set_uid() until the private hostkey is destroyed | |
613 | * with RSA_free(). Otherwise the calling user could ptrace() the | |
614 | * process, read the private hostkey and impersonate the host. | |
615 | * OpenBSD does not allow ptracing of setuid processes. | |
616 | */ | |
617 | permanently_set_uid(original_real_uid); | |
618 | ||
619 | /* | |
620 | * Now that we are back to our own permissions, create ~/.ssh | |
621 | * directory if it doesn\'t already exist. | |
622 | */ | |
623 | snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR); | |
624 | if (stat(buf, &st) < 0) | |
625 | if (mkdir(buf, 0755) < 0) | |
626 | error("Could not create directory '%.200s'.", buf); | |
627 | ||
628 | /* Check if the connection failed, and try "rsh" if appropriate. */ | |
629 | if (!ok) { | |
630 | if (options.port != 0) | |
631 | log("Secure connection to %.100s on port %hu refused%.100s.", | |
632 | host, options.port, | |
633 | options.fallback_to_rsh ? "; reverting to insecure method" : ""); | |
634 | else | |
635 | log("Secure connection to %.100s refused%.100s.", host, | |
636 | options.fallback_to_rsh ? "; reverting to insecure method" : ""); | |
637 | ||
638 | if (options.fallback_to_rsh) { | |
639 | rsh_connect(host, options.user, &command); | |
640 | fatal("rsh_connect returned"); | |
641 | } | |
642 | exit(1); | |
643 | } | |
644 | /* Expand ~ in options.identity_files. */ | |
645 | /* XXX mem-leaks */ | |
646 | for (i = 0; i < options.num_identity_files; i++) | |
647 | options.identity_files[i] = | |
648 | tilde_expand_filename(options.identity_files[i], original_real_uid); | |
649 | for (i = 0; i < options.num_identity_files2; i++) | |
650 | options.identity_files2[i] = | |
651 | tilde_expand_filename(options.identity_files2[i], original_real_uid); | |
652 | /* Expand ~ in known host file names. */ | |
653 | options.system_hostfile = tilde_expand_filename(options.system_hostfile, | |
654 | original_real_uid); | |
655 | options.user_hostfile = tilde_expand_filename(options.user_hostfile, | |
656 | original_real_uid); | |
657 | options.system_hostfile2 = tilde_expand_filename(options.system_hostfile2, | |
658 | original_real_uid); | |
659 | options.user_hostfile2 = tilde_expand_filename(options.user_hostfile2, | |
660 | original_real_uid); | |
661 | ||
662 | /* Log into the remote system. This never returns if the login fails. */ | |
663 | ssh_login(host_private_key_loaded, host_private_key, | |
664 | host, (struct sockaddr *)&hostaddr, original_real_uid); | |
665 | ||
666 | /* We no longer need the host private key. Clear it now. */ | |
667 | if (host_private_key_loaded) | |
668 | RSA_free(host_private_key); /* Destroys contents safely */ | |
669 | ||
670 | exit_status = compat20 ? ssh_session2() : ssh_session(); | |
671 | packet_close(); | |
672 | return exit_status; | |
673 | } | |
674 | ||
675 | void | |
676 | x11_get_proto(char *proto, int proto_len, char *data, int data_len) | |
677 | { | |
678 | char line[512]; | |
679 | FILE *f; | |
680 | int got_data = 0, i; | |
681 | ||
682 | if (options.xauth_location) { | |
683 | /* Try to get Xauthority information for the display. */ | |
684 | snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null", | |
685 | options.xauth_location, getenv("DISPLAY")); | |
686 | f = popen(line, "r"); | |
687 | if (f && fgets(line, sizeof(line), f) && | |
688 | sscanf(line, "%*s %s %s", proto, data) == 2) | |
689 | got_data = 1; | |
690 | if (f) | |
691 | pclose(f); | |
692 | } | |
693 | /* | |
694 | * If we didn't get authentication data, just make up some | |
695 | * data. The forwarding code will check the validity of the | |
696 | * response anyway, and substitute this data. The X11 | |
697 | * server, however, will ignore this fake data and use | |
698 | * whatever authentication mechanisms it was using otherwise | |
699 | * for the local connection. | |
700 | */ | |
701 | if (!got_data) { | |
702 | u_int32_t rand = 0; | |
703 | ||
704 | strlcpy(proto, "MIT-MAGIC-COOKIE-1", proto_len); | |
705 | for (i = 0; i < 16; i++) { | |
706 | if (i % 4 == 0) | |
707 | rand = arc4random(); | |
708 | snprintf(data + 2 * i, data_len - 2 * i, "%02x", rand & 0xff); | |
709 | rand >>= 8; | |
710 | } | |
711 | } | |
712 | } | |
713 | ||
714 | int | |
715 | ssh_session(void) | |
716 | { | |
717 | int type; | |
718 | int i; | |
719 | int plen; | |
720 | int interactive = 0; | |
721 | int have_tty = 0; | |
722 | struct winsize ws; | |
723 | int authfd; | |
724 | char *cp; | |
725 | ||
726 | /* Enable compression if requested. */ | |
727 | if (options.compression) { | |
728 | debug("Requesting compression at level %d.", options.compression_level); | |
729 | ||
730 | if (options.compression_level < 1 || options.compression_level > 9) | |
731 | fatal("Compression level must be from 1 (fast) to 9 (slow, best)."); | |
732 | ||
733 | /* Send the request. */ | |
734 | packet_start(SSH_CMSG_REQUEST_COMPRESSION); | |
735 | packet_put_int(options.compression_level); | |
736 | packet_send(); | |
737 | packet_write_wait(); | |
738 | type = packet_read(&plen); | |
739 | if (type == SSH_SMSG_SUCCESS) | |
740 | packet_start_compression(options.compression_level); | |
741 | else if (type == SSH_SMSG_FAILURE) | |
742 | log("Warning: Remote host refused compression."); | |
743 | else | |
744 | packet_disconnect("Protocol error waiting for compression response."); | |
745 | } | |
746 | /* Allocate a pseudo tty if appropriate. */ | |
747 | if (tty_flag) { | |
748 | debug("Requesting pty."); | |
749 | ||
750 | /* Start the packet. */ | |
751 | packet_start(SSH_CMSG_REQUEST_PTY); | |
752 | ||
753 | /* Store TERM in the packet. There is no limit on the | |
754 | length of the string. */ | |
755 | cp = getenv("TERM"); | |
756 | if (!cp) | |
757 | cp = ""; | |
758 | packet_put_string(cp, strlen(cp)); | |
759 | ||
760 | /* Store window size in the packet. */ | |
761 | if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) | |
762 | memset(&ws, 0, sizeof(ws)); | |
763 | packet_put_int(ws.ws_row); | |
764 | packet_put_int(ws.ws_col); | |
765 | packet_put_int(ws.ws_xpixel); | |
766 | packet_put_int(ws.ws_ypixel); | |
767 | ||
768 | /* Store tty modes in the packet. */ | |
769 | tty_make_modes(fileno(stdin)); | |
770 | ||
771 | /* Send the packet, and wait for it to leave. */ | |
772 | packet_send(); | |
773 | packet_write_wait(); | |
774 | ||
775 | /* Read response from the server. */ | |
776 | type = packet_read(&plen); | |
777 | if (type == SSH_SMSG_SUCCESS) { | |
778 | interactive = 1; | |
779 | have_tty = 1; | |
780 | } else if (type == SSH_SMSG_FAILURE) | |
781 | log("Warning: Remote host failed or refused to allocate a pseudo tty."); | |
782 | else | |
783 | packet_disconnect("Protocol error waiting for pty request response."); | |
784 | } | |
785 | /* Request X11 forwarding if enabled and DISPLAY is set. */ | |
786 | if (options.forward_x11 && getenv("DISPLAY") != NULL) { | |
787 | char proto[512], data[512]; | |
788 | /* Get reasonable local authentication information. */ | |
789 | x11_get_proto(proto, sizeof proto, data, sizeof data); | |
790 | /* Request forwarding with authentication spoofing. */ | |
791 | debug("Requesting X11 forwarding with authentication spoofing."); | |
792 | x11_request_forwarding_with_spoofing(0, proto, data); | |
793 | ||
794 | /* Read response from the server. */ | |
795 | type = packet_read(&plen); | |
796 | if (type == SSH_SMSG_SUCCESS) { | |
797 | interactive = 1; | |
798 | } else if (type == SSH_SMSG_FAILURE) { | |
799 | log("Warning: Remote host denied X11 forwarding."); | |
800 | } else { | |
801 | packet_disconnect("Protocol error waiting for X11 forwarding"); | |
802 | } | |
803 | } | |
804 | /* Tell the packet module whether this is an interactive session. */ | |
805 | packet_set_interactive(interactive, options.keepalives); | |
806 | ||
807 | /* Clear agent forwarding if we don\'t have an agent. */ | |
808 | authfd = ssh_get_authentication_socket(); | |
809 | if (authfd < 0) | |
810 | options.forward_agent = 0; | |
811 | else | |
812 | ssh_close_authentication_socket(authfd); | |
813 | ||
814 | /* Request authentication agent forwarding if appropriate. */ | |
815 | if (options.forward_agent) { | |
816 | debug("Requesting authentication agent forwarding."); | |
817 | auth_request_forwarding(); | |
818 | ||
819 | /* Read response from the server. */ | |
820 | type = packet_read(&plen); | |
821 | packet_integrity_check(plen, 0, type); | |
822 | if (type != SSH_SMSG_SUCCESS) | |
823 | log("Warning: Remote host denied authentication agent forwarding."); | |
824 | } | |
825 | /* Initiate local TCP/IP port forwardings. */ | |
826 | for (i = 0; i < options.num_local_forwards; i++) { | |
827 | debug("Connections to local port %d forwarded to remote address %.200s:%d", | |
828 | options.local_forwards[i].port, | |
829 | options.local_forwards[i].host, | |
830 | options.local_forwards[i].host_port); | |
831 | channel_request_local_forwarding(options.local_forwards[i].port, | |
832 | options.local_forwards[i].host, | |
833 | options.local_forwards[i].host_port, | |
834 | options.gateway_ports); | |
835 | } | |
836 | ||
837 | /* Initiate remote TCP/IP port forwardings. */ | |
838 | for (i = 0; i < options.num_remote_forwards; i++) { | |
839 | debug("Connections to remote port %d forwarded to local address %.200s:%d", | |
840 | options.remote_forwards[i].port, | |
841 | options.remote_forwards[i].host, | |
842 | options.remote_forwards[i].host_port); | |
843 | channel_request_remote_forwarding(options.remote_forwards[i].port, | |
844 | options.remote_forwards[i].host, | |
845 | options.remote_forwards[i].host_port); | |
846 | } | |
847 | ||
848 | /* If requested, let ssh continue in the background. */ | |
849 | if (fork_after_authentication_flag) | |
850 | if (daemon(1, 1) < 0) | |
851 | fatal("daemon() failed: %.200s", strerror(errno)); | |
852 | ||
853 | /* | |
854 | * If a command was specified on the command line, execute the | |
855 | * command now. Otherwise request the server to start a shell. | |
856 | */ | |
857 | if (buffer_len(&command) > 0) { | |
858 | int len = buffer_len(&command); | |
859 | if (len > 900) | |
860 | len = 900; | |
861 | debug("Sending command: %.*s", len, buffer_ptr(&command)); | |
862 | packet_start(SSH_CMSG_EXEC_CMD); | |
863 | packet_put_string(buffer_ptr(&command), buffer_len(&command)); | |
864 | packet_send(); | |
865 | packet_write_wait(); | |
866 | } else { | |
867 | debug("Requesting shell."); | |
868 | packet_start(SSH_CMSG_EXEC_SHELL); | |
869 | packet_send(); | |
870 | packet_write_wait(); | |
871 | } | |
872 | ||
873 | /* Enter the interactive session. */ | |
874 | return client_loop(have_tty, tty_flag ? options.escape_char : -1); | |
875 | } | |
876 | ||
877 | void | |
878 | init_local_fwd(void) | |
879 | { | |
880 | int i; | |
881 | /* Initiate local TCP/IP port forwardings. */ | |
882 | for (i = 0; i < options.num_local_forwards; i++) { | |
883 | debug("Connections to local port %d forwarded to remote address %.200s:%d", | |
884 | options.local_forwards[i].port, | |
885 | options.local_forwards[i].host, | |
886 | options.local_forwards[i].host_port); | |
887 | channel_request_local_forwarding(options.local_forwards[i].port, | |
888 | options.local_forwards[i].host, | |
889 | options.local_forwards[i].host_port, | |
890 | options.gateway_ports); | |
891 | } | |
892 | } | |
893 | ||
894 | extern void client_set_session_ident(int id); | |
895 | ||
896 | void | |
897 | client_init(int id, void *arg) | |
898 | { | |
899 | int len; | |
900 | debug("client_init id %d arg %d", id, (int)arg); | |
901 | ||
902 | if (no_shell_flag) | |
903 | goto done; | |
904 | ||
905 | if (tty_flag) { | |
906 | struct winsize ws; | |
907 | char *cp; | |
908 | cp = getenv("TERM"); | |
909 | if (!cp) | |
910 | cp = ""; | |
911 | /* Store window size in the packet. */ | |
912 | if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) | |
913 | memset(&ws, 0, sizeof(ws)); | |
914 | ||
915 | channel_request_start(id, "pty-req", 0); | |
916 | packet_put_cstring(cp); | |
917 | packet_put_int(ws.ws_col); | |
918 | packet_put_int(ws.ws_row); | |
919 | packet_put_int(ws.ws_xpixel); | |
920 | packet_put_int(ws.ws_ypixel); | |
921 | packet_put_cstring(""); /* XXX: encode terminal modes */ | |
922 | packet_send(); | |
923 | /* XXX wait for reply */ | |
924 | } | |
925 | if (options.forward_x11 && | |
926 | getenv("DISPLAY") != NULL) { | |
927 | char proto[512], data[512]; | |
928 | /* Get reasonable local authentication information. */ | |
929 | x11_get_proto(proto, sizeof proto, data, sizeof data); | |
930 | /* Request forwarding with authentication spoofing. */ | |
931 | debug("Requesting X11 forwarding with authentication spoofing."); | |
932 | x11_request_forwarding_with_spoofing(id, proto, data); | |
933 | /* XXX wait for reply */ | |
934 | } | |
935 | ||
936 | len = buffer_len(&command); | |
937 | if (len > 0) { | |
938 | if (len > 900) | |
939 | len = 900; | |
940 | debug("Sending command: %.*s", len, buffer_ptr(&command)); | |
941 | channel_request_start(id, "exec", 0); | |
942 | packet_put_string(buffer_ptr(&command), len); | |
943 | packet_send(); | |
944 | } else { | |
945 | channel_request(id, "shell", 0); | |
946 | } | |
947 | /* channel_callback(id, SSH2_MSG_OPEN_CONFIGMATION, client_init, 0); */ | |
948 | done: | |
949 | /* register different callback, etc. XXX */ | |
950 | client_set_session_ident(id); | |
951 | } | |
952 | ||
953 | int | |
954 | ssh_session2(void) | |
955 | { | |
956 | int window, packetmax, id; | |
957 | int in = dup(STDIN_FILENO); | |
958 | int out = dup(STDOUT_FILENO); | |
959 | int err = dup(STDERR_FILENO); | |
960 | ||
961 | if (in < 0 || out < 0 || err < 0) | |
962 | fatal("dump in/out/err failed"); | |
963 | ||
964 | /* should be pre-session */ | |
965 | init_local_fwd(); | |
966 | ||
967 | window = 32*1024; | |
968 | if (tty_flag) { | |
969 | packetmax = window/8; | |
970 | } else { | |
971 | window *= 2; | |
972 | packetmax = window/2; | |
973 | } | |
974 | ||
975 | id = channel_new( | |
976 | "session", SSH_CHANNEL_OPENING, in, out, err, | |
977 | window, packetmax, CHAN_EXTENDED_WRITE, xstrdup("client-session")); | |
978 | ||
979 | ||
980 | channel_open(id); | |
981 | channel_register_callback(id, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, client_init, (void *)0); | |
982 | ||
983 | return client_loop(tty_flag, tty_flag ? options.escape_char : -1); | |
984 | } |