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