Annotation of src/usr.bin/ssh/ssh.c, Revision 1.43
1.1 deraadt 1: /*
1.32 deraadt 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: */
1.1 deraadt 12:
13: #include "includes.h"
1.43 ! markus 14: RCSID("$Id: ssh.c,v 1.42 2000/03/22 09:55:10 markus Exp $");
1.1 deraadt 15:
16: #include "xmalloc.h"
17: #include "ssh.h"
18: #include "packet.h"
19: #include "buffer.h"
20: #include "authfd.h"
21: #include "readconf.h"
22: #include "uidswap.h"
23:
1.37 markus 24: /* Flag indicating whether IPv4 or IPv6. This can be set on the command line.
25: Default value is AF_UNSPEC means both IPv4 and IPv6. */
26: int IPv4or6 = AF_UNSPEC;
27:
1.31 markus 28: /* Flag indicating whether debug mode is on. This can be set on the command line. */
1.1 deraadt 29: int debug_flag = 0;
30:
31: int tty_flag = 0;
32:
1.33 markus 33: /*
34: * Flag indicating that nothing should be read from stdin. This can be set
35: * on the command line.
36: */
1.1 deraadt 37: int stdin_null_flag = 0;
38:
1.33 markus 39: /*
40: * Flag indicating that ssh should fork after authentication. This is useful
41: * so that the pasphrase can be entered manually, and then ssh goes to the
42: * background.
43: */
1.1 deraadt 44: int fork_after_authentication_flag = 0;
45:
1.33 markus 46: /*
47: * General data structure for command line options and options configurable
48: * in configuration files. See readconf.h.
49: */
1.1 deraadt 50: Options options;
51:
1.33 markus 52: /*
53: * Name of the host we are connecting to. This is the name given on the
54: * command line, or the HostName specified for the user-supplied name in a
55: * configuration file.
56: */
1.1 deraadt 57: char *host;
58:
1.22 provos 59: /* socket address the host resolves to */
1.37 markus 60: struct sockaddr_storage hostaddr;
1.22 provos 61:
1.33 markus 62: /*
63: * Flag to indicate that we have received a window change signal which has
64: * not yet been processed. This will cause a message indicating the new
65: * window size to be sent to the server a little later. This is volatile
66: * because this is updated in a signal handler.
67: */
1.1 deraadt 68: volatile int received_window_change_signal = 0;
69:
70: /* Value of argv[0] (set in the main program). */
71: char *av0;
72:
73: /* Flag indicating whether we have a valid host private key loaded. */
74: int host_private_key_loaded = 0;
75:
76: /* Host private key. */
1.2 provos 77: RSA *host_private_key = NULL;
1.1 deraadt 78:
1.10 dugsong 79: /* Original real UID. */
80: uid_t original_real_uid;
1.1 deraadt 81:
82: /* Prints a help message to the user. This function never returns. */
83:
1.2 provos 84: void
85: usage()
1.1 deraadt 86: {
1.31 markus 87: fprintf(stderr, "Usage: %s [options] host [command]\n", av0);
88: fprintf(stderr, "Options:\n");
89: fprintf(stderr, " -l user Log in using this user name.\n");
90: fprintf(stderr, " -n Redirect input from /dev/null.\n");
91: fprintf(stderr, " -a Disable authentication agent forwarding.\n");
1.9 dugsong 92: #ifdef AFS
1.31 markus 93: fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n");
94: #endif /* AFS */
95: fprintf(stderr, " -x Disable X11 connection forwarding.\n");
1.41 markus 96: fprintf(stderr, " -X Enable X11 connection forwarding.\n");
1.31 markus 97: fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n");
98: fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n");
99: fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
100: fprintf(stderr, " -V Display version number only.\n");
101: fprintf(stderr, " -P Don't allocate a privileged port.\n");
102: fprintf(stderr, " -q Quiet; don't display any warning messages.\n");
103: fprintf(stderr, " -f Fork into background after authentication.\n");
104: fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n");
105:
106: fprintf(stderr, " -c cipher Select encryption algorithm: "
107: "``3des'', "
108: "``blowfish''\n");
109: fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n");
110: fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n");
111: fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n");
112: fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0);
113: fprintf(stderr, " forward them to the other side by connecting to host:port.\n");
114: fprintf(stderr, " -C Enable compression.\n");
115: fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n");
1.37 markus 116: fprintf(stderr, " -4 Use IPv4 only.\n");
117: fprintf(stderr, " -6 Use IPv6 only.\n");
1.31 markus 118: fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n");
119: exit(1);
1.1 deraadt 120: }
121:
1.32 deraadt 122: /*
123: * Connects to the given host using rsh (or prints an error message and exits
124: * if rsh is not available). This function never returns.
125: */
1.2 provos 126: void
1.31 markus 127: rsh_connect(char *host, char *user, Buffer * command)
1.1 deraadt 128: {
1.31 markus 129: char *args[10];
130: int i;
131:
132: log("Using rsh. WARNING: Connection will not be encrypted.");
133: /* Build argument list for rsh. */
134: i = 0;
135: args[i++] = _PATH_RSH;
136: /* host may have to come after user on some systems */
137: args[i++] = host;
138: if (user) {
139: args[i++] = "-l";
140: args[i++] = user;
141: }
142: if (buffer_len(command) > 0) {
143: buffer_append(command, "\0", 1);
144: args[i++] = buffer_ptr(command);
145: }
146: args[i++] = NULL;
147: if (debug_flag) {
148: for (i = 0; args[i]; i++) {
149: if (i != 0)
150: fprintf(stderr, " ");
151: fprintf(stderr, "%s", args[i]);
152: }
153: fprintf(stderr, "\n");
154: }
155: execv(_PATH_RSH, args);
156: perror(_PATH_RSH);
157: exit(1);
1.1 deraadt 158: }
159:
1.32 deraadt 160: /*
161: * Main program for the ssh client.
162: */
1.2 provos 163: int
164: main(int ac, char **av)
1.1 deraadt 165: {
1.35 markus 166: int i, opt, optind, type, exit_status, ok, authfd;
167: u_short fwd_port, fwd_host_port;
1.31 markus 168: char *optarg, *cp, buf[256];
169: Buffer command;
170: struct winsize ws;
171: struct stat st;
172: struct passwd *pw, pwcopy;
173: int interactive = 0, dummy;
1.43 ! markus 174: int have_pty = 0;
1.31 markus 175: uid_t original_effective_uid;
176: int plen;
177:
1.33 markus 178: /*
179: * Save the original real uid. It will be needed later (uid-swapping
180: * may clobber the real uid).
181: */
1.31 markus 182: original_real_uid = getuid();
183: original_effective_uid = geteuid();
184:
185: /* If we are installed setuid root be careful to not drop core. */
186: if (original_real_uid != original_effective_uid) {
187: struct rlimit rlim;
188: rlim.rlim_cur = rlim.rlim_max = 0;
189: if (setrlimit(RLIMIT_CORE, &rlim) < 0)
190: fatal("setrlimit failed: %.100s", strerror(errno));
1.1 deraadt 191: }
1.33 markus 192: /*
193: * Use uid-swapping to give up root privileges for the duration of
194: * option processing. We will re-instantiate the rights when we are
195: * ready to create the privileged port, and will permanently drop
196: * them when the port has been created (actually, when the connection
197: * has been made, as we may need to create the port several times).
198: */
1.31 markus 199: temporarily_use_uid(original_real_uid);
200:
1.33 markus 201: /*
202: * Set our umask to something reasonable, as some files are created
203: * with the default umask. This will make them world-readable but
204: * writable only by the owner, which is ok for all files for which we
205: * don't set the modes explicitly.
206: */
1.31 markus 207: umask(022);
208:
209: /* Save our own name. */
210: av0 = av[0];
211:
212: /* Initialize option structure to indicate that no values have been set. */
213: initialize_options(&options);
214:
215: /* Parse command-line arguments. */
216: host = NULL;
217:
218: /* If program name is not one of the standard names, use it as host name. */
219: if (strchr(av0, '/'))
220: cp = strrchr(av0, '/') + 1;
221: else
222: cp = av0;
223: if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 &&
224: strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0)
225: host = cp;
226:
227: for (optind = 1; optind < ac; optind++) {
228: if (av[optind][0] != '-') {
229: if (host)
230: break;
231: if ((cp = strchr(av[optind], '@'))) {
1.38 markus 232: if(cp == av[optind])
233: usage();
1.31 markus 234: options.user = av[optind];
235: *cp = '\0';
236: host = ++cp;
237: } else
238: host = av[optind];
239: continue;
240: }
241: opt = av[optind][1];
242: if (!opt)
243: usage();
244: if (strchr("eilcpLRo", opt)) { /* options with arguments */
245: optarg = av[optind] + 2;
246: if (strcmp(optarg, "") == 0) {
247: if (optind >= ac - 1)
248: usage();
249: optarg = av[++optind];
250: }
251: } else {
252: if (av[optind][2])
253: usage();
254: optarg = NULL;
255: }
256: switch (opt) {
1.37 markus 257: case '4':
258: IPv4or6 = AF_INET;
259: break;
260:
261: case '6':
262: IPv4or6 = AF_INET6;
263: break;
264:
1.31 markus 265: case 'n':
266: stdin_null_flag = 1;
267: break;
268:
269: case 'f':
270: fork_after_authentication_flag = 1;
271: stdin_null_flag = 1;
272: break;
273:
274: case 'x':
275: options.forward_x11 = 0;
276: break;
277:
278: case 'X':
279: options.forward_x11 = 1;
280: break;
281:
282: case 'g':
283: options.gateway_ports = 1;
284: break;
285:
286: case 'P':
287: options.use_privileged_port = 0;
288: break;
289:
290: case 'a':
291: options.forward_agent = 0;
292: break;
1.9 dugsong 293: #ifdef AFS
1.31 markus 294: case 'k':
295: options.kerberos_tgt_passing = 0;
296: options.afs_token_passing = 0;
297: break;
1.1 deraadt 298: #endif
1.31 markus 299: case 'i':
300: if (stat(optarg, &st) < 0) {
301: fprintf(stderr, "Warning: Identity file %s does not exist.\n",
302: optarg);
303: break;
304: }
305: if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES)
306: fatal("Too many identity files specified (max %d)",
307: SSH_MAX_IDENTITY_FILES);
308: options.identity_files[options.num_identity_files++] =
309: xstrdup(optarg);
310: break;
311:
312: case 't':
313: tty_flag = 1;
314: break;
315:
316: case 'v':
317: case 'V':
318: fprintf(stderr, "SSH Version %s, protocol version %d.%d.\n",
319: SSH_VERSION, PROTOCOL_MAJOR, PROTOCOL_MINOR);
320: fprintf(stderr, "Compiled with SSL.\n");
321: if (opt == 'V')
322: exit(0);
323: debug_flag = 1;
324: options.log_level = SYSLOG_LEVEL_DEBUG;
325: break;
326:
327: case 'q':
328: options.log_level = SYSLOG_LEVEL_QUIET;
329: break;
330:
331: case 'e':
332: if (optarg[0] == '^' && optarg[2] == 0 &&
333: (unsigned char) optarg[1] >= 64 && (unsigned char) optarg[1] < 128)
334: options.escape_char = (unsigned char) optarg[1] & 31;
335: else if (strlen(optarg) == 1)
336: options.escape_char = (unsigned char) optarg[0];
337: else if (strcmp(optarg, "none") == 0)
338: options.escape_char = -2;
339: else {
340: fprintf(stderr, "Bad escape character '%s'.\n", optarg);
341: exit(1);
342: }
343: break;
344:
345: case 'c':
346: options.cipher = cipher_number(optarg);
347: if (options.cipher == -1) {
348: fprintf(stderr, "Unknown cipher type '%s'\n", optarg);
349: exit(1);
350: }
351: break;
352:
353: case 'p':
354: options.port = atoi(optarg);
355: break;
356:
357: case 'l':
358: options.user = optarg;
359: break;
360:
361: case 'R':
1.37 markus 362: if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
363: &fwd_host_port) != 3 &&
364: sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
365: &fwd_host_port) != 3) {
1.31 markus 366: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
367: usage();
368: /* NOTREACHED */
369: }
370: add_remote_forward(&options, fwd_port, buf, fwd_host_port);
371: break;
372:
373: case 'L':
1.37 markus 374: if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
375: &fwd_host_port) != 3 &&
376: sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
377: &fwd_host_port) != 3) {
1.31 markus 378: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
379: usage();
380: /* NOTREACHED */
381: }
382: add_local_forward(&options, fwd_port, buf, fwd_host_port);
383: break;
384:
385: case 'C':
386: options.compression = 1;
387: break;
388:
389: case 'o':
390: dummy = 1;
391: if (process_config_line(&options, host ? host : "", optarg,
392: "command-line", 0, &dummy) != 0)
393: exit(1);
394: break;
395:
396: default:
397: usage();
1.1 deraadt 398: }
1.31 markus 399: }
400:
401: /* Check that we got a host name. */
402: if (!host)
403: usage();
404:
405: /* check if RSA support exists */
406: if (rsa_alive() == 0) {
407: extern char *__progname;
408:
409: fprintf(stderr,
410: "%s: no RSA support in libssl and libcrypto. See ssl(8).\n",
411: __progname);
412: exit(1);
413: }
414: /* Initialize the command to execute on remote host. */
415: buffer_init(&command);
1.1 deraadt 416:
1.33 markus 417: /*
418: * Save the command to execute on the remote host in a buffer. There
419: * is no limit on the length of the command, except by the maximum
420: * packet size. Also sets the tty flag if there is no command.
421: */
1.31 markus 422: if (optind == ac) {
423: /* No command specified - execute shell on a tty. */
424: tty_flag = 1;
425: } else {
426: /* A command has been specified. Store it into the
427: buffer. */
428: for (i = optind; i < ac; i++) {
429: if (i > optind)
430: buffer_append(&command, " ", 1);
431: buffer_append(&command, av[i], strlen(av[i]));
432: }
433: }
434:
435: /* Cannot fork to background if no command. */
436: if (fork_after_authentication_flag && buffer_len(&command) == 0)
437: fatal("Cannot fork into background without a command to execute.");
438:
439: /* Allocate a tty by default if no command specified. */
440: if (buffer_len(&command) == 0)
441: tty_flag = 1;
442:
443: /* Do not allocate a tty if stdin is not a tty. */
444: if (!isatty(fileno(stdin))) {
445: if (tty_flag)
446: fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n");
447: tty_flag = 0;
448: }
449: /* Get user data. */
450: pw = getpwuid(original_real_uid);
451: if (!pw) {
452: fprintf(stderr, "You don't exist, go away!\n");
453: exit(1);
454: }
455: /* Take a copy of the returned structure. */
456: memset(&pwcopy, 0, sizeof(pwcopy));
457: pwcopy.pw_name = xstrdup(pw->pw_name);
458: pwcopy.pw_passwd = xstrdup(pw->pw_passwd);
459: pwcopy.pw_uid = pw->pw_uid;
460: pwcopy.pw_gid = pw->pw_gid;
461: pwcopy.pw_dir = xstrdup(pw->pw_dir);
462: pwcopy.pw_shell = xstrdup(pw->pw_shell);
463: pw = &pwcopy;
464:
465: /* Initialize "log" output. Since we are the client all output
466: actually goes to the terminal. */
467: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
468:
469: /* Read per-user configuration file. */
470: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE);
471: read_config_file(buf, host, &options);
472:
473: /* Read systemwide configuration file. */
474: read_config_file(HOST_CONFIG_FILE, host, &options);
475:
476: /* Fill configuration defaults. */
477: fill_default_options(&options);
478:
479: /* reinit */
480: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
481:
482: if (options.user == NULL)
483: options.user = xstrdup(pw->pw_name);
484:
485: if (options.hostname != NULL)
486: host = options.hostname;
487:
488: /* Find canonic host name. */
489: if (strchr(host, '.') == 0) {
1.37 markus 490: struct addrinfo hints;
491: struct addrinfo *ai = NULL;
492: int errgai;
493: memset(&hints, 0, sizeof(hints));
1.40 markus 494: hints.ai_family = IPv4or6;
1.37 markus 495: hints.ai_flags = AI_CANONNAME;
1.39 markus 496: hints.ai_socktype = SOCK_STREAM;
1.37 markus 497: errgai = getaddrinfo(host, NULL, &hints, &ai);
498: if (errgai == 0) {
499: if (ai->ai_canonname != NULL)
500: host = xstrdup(ai->ai_canonname);
501: freeaddrinfo(ai);
1.31 markus 502: }
503: }
504: /* Disable rhosts authentication if not running as root. */
505: if (original_effective_uid != 0 || !options.use_privileged_port) {
506: options.rhosts_authentication = 0;
507: options.rhosts_rsa_authentication = 0;
508: }
1.33 markus 509: /*
510: * If using rsh has been selected, exec it now (without trying
511: * anything else). Note that we must release privileges first.
512: */
1.31 markus 513: if (options.use_rsh) {
1.33 markus 514: /*
515: * Restore our superuser privileges. This must be done
516: * before permanently setting the uid.
517: */
1.31 markus 518: restore_uid();
519:
520: /* Switch to the original uid permanently. */
521: permanently_set_uid(original_real_uid);
522:
523: /* Execute rsh. */
524: rsh_connect(host, options.user, &command);
525: fatal("rsh_connect returned");
526: }
527: /* Restore our superuser privileges. */
528: restore_uid();
529:
1.33 markus 530: /*
531: * Open a connection to the remote host. This needs root privileges
532: * if rhosts_{rsa_}authentication is enabled.
533: */
1.31 markus 534:
535: ok = ssh_connect(host, &hostaddr, options.port,
536: options.connection_attempts,
537: !options.rhosts_authentication &&
538: !options.rhosts_rsa_authentication,
539: original_real_uid,
540: options.proxy_command);
541:
1.33 markus 542: /*
543: * If we successfully made the connection, load the host private key
544: * in case we will need it later for combined rsa-rhosts
545: * authentication. This must be done before releasing extra
546: * privileges, because the file is only readable by root.
547: */
1.31 markus 548: if (ok) {
549: host_private_key = RSA_new();
550: if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL))
551: host_private_key_loaded = 1;
552: }
1.33 markus 553: /*
554: * Get rid of any extra privileges that we may have. We will no
555: * longer need them. Also, extra privileges could make it very hard
556: * to read identity files and other non-world-readable files from the
557: * user's home directory if it happens to be on a NFS volume where
558: * root is mapped to nobody.
559: */
560:
561: /*
562: * Note that some legacy systems need to postpone the following call
563: * to permanently_set_uid() until the private hostkey is destroyed
564: * with RSA_free(). Otherwise the calling user could ptrace() the
565: * process, read the private hostkey and impersonate the host.
566: * OpenBSD does not allow ptracing of setuid processes.
567: */
1.31 markus 568: permanently_set_uid(original_real_uid);
569:
1.33 markus 570: /*
571: * Now that we are back to our own permissions, create ~/.ssh
572: * directory if it doesn\'t already exist.
573: */
1.31 markus 574: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR);
575: if (stat(buf, &st) < 0)
576: if (mkdir(buf, 0755) < 0)
577: error("Could not create directory '%.200s'.", buf);
578:
579: /* Check if the connection failed, and try "rsh" if appropriate. */
580: if (!ok) {
581: if (options.port != 0)
1.35 markus 582: log("Secure connection to %.100s on port %hu refused%.100s.",
1.31 markus 583: host, options.port,
584: options.fallback_to_rsh ? "; reverting to insecure method" : "");
585: else
586: log("Secure connection to %.100s refused%.100s.", host,
587: options.fallback_to_rsh ? "; reverting to insecure method" : "");
588:
589: if (options.fallback_to_rsh) {
590: rsh_connect(host, options.user, &command);
591: fatal("rsh_connect returned");
592: }
593: exit(1);
594: }
595: /* Expand ~ in options.identity_files. */
596: for (i = 0; i < options.num_identity_files; i++)
597: options.identity_files[i] =
598: tilde_expand_filename(options.identity_files[i], original_real_uid);
599:
600: /* Expand ~ in known host file names. */
601: options.system_hostfile = tilde_expand_filename(options.system_hostfile,
602: original_real_uid);
603: options.user_hostfile = tilde_expand_filename(options.user_hostfile,
604: original_real_uid);
605:
606: /* Log into the remote system. This never returns if the login fails. */
607: ssh_login(host_private_key_loaded, host_private_key,
1.37 markus 608: host, (struct sockaddr *)&hostaddr, original_real_uid);
1.31 markus 609:
610: /* We no longer need the host private key. Clear it now. */
611: if (host_private_key_loaded)
612: RSA_free(host_private_key); /* Destroys contents safely */
613:
614: /* Enable compression if requested. */
615: if (options.compression) {
616: debug("Requesting compression at level %d.", options.compression_level);
617:
618: if (options.compression_level < 1 || options.compression_level > 9)
619: fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
620:
621: /* Send the request. */
622: packet_start(SSH_CMSG_REQUEST_COMPRESSION);
623: packet_put_int(options.compression_level);
624: packet_send();
625: packet_write_wait();
626: type = packet_read(&plen);
627: if (type == SSH_SMSG_SUCCESS)
628: packet_start_compression(options.compression_level);
629: else if (type == SSH_SMSG_FAILURE)
630: log("Warning: Remote host refused compression.");
631: else
632: packet_disconnect("Protocol error waiting for compression response.");
633: }
634: /* Allocate a pseudo tty if appropriate. */
635: if (tty_flag) {
636: debug("Requesting pty.");
637:
638: /* Start the packet. */
639: packet_start(SSH_CMSG_REQUEST_PTY);
640:
641: /* Store TERM in the packet. There is no limit on the
642: length of the string. */
643: cp = getenv("TERM");
644: if (!cp)
645: cp = "";
646: packet_put_string(cp, strlen(cp));
647:
648: /* Store window size in the packet. */
649: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
650: memset(&ws, 0, sizeof(ws));
651: packet_put_int(ws.ws_row);
652: packet_put_int(ws.ws_col);
653: packet_put_int(ws.ws_xpixel);
654: packet_put_int(ws.ws_ypixel);
655:
656: /* Store tty modes in the packet. */
657: tty_make_modes(fileno(stdin));
658:
659: /* Send the packet, and wait for it to leave. */
660: packet_send();
661: packet_write_wait();
662:
663: /* Read response from the server. */
664: type = packet_read(&plen);
1.43 ! markus 665: if (type == SSH_SMSG_SUCCESS) {
1.31 markus 666: interactive = 1;
1.43 ! markus 667: have_pty = 1;
! 668: } else if (type == SSH_SMSG_FAILURE)
1.31 markus 669: log("Warning: Remote host failed or refused to allocate a pseudo tty.");
670: else
671: packet_disconnect("Protocol error waiting for pty request response.");
672: }
673: /* Request X11 forwarding if enabled and DISPLAY is set. */
674: if (options.forward_x11 && getenv("DISPLAY") != NULL) {
675: char line[512], proto[512], data[512];
676: FILE *f;
677: int forwarded = 0, got_data = 0, i;
1.1 deraadt 678:
679: #ifdef XAUTH_PATH
1.31 markus 680: /* Try to get Xauthority information for the display. */
681: snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null",
682: XAUTH_PATH, getenv("DISPLAY"));
683: f = popen(line, "r");
684: if (f && fgets(line, sizeof(line), f) &&
685: sscanf(line, "%*s %s %s", proto, data) == 2)
686: got_data = 1;
687: if (f)
688: pclose(f);
1.1 deraadt 689: #endif /* XAUTH_PATH */
1.33 markus 690: /*
691: * If we didn't get authentication data, just make up some
692: * data. The forwarding code will check the validity of the
693: * response anyway, and substitute this data. The X11
694: * server, however, will ignore this fake data and use
695: * whatever authentication mechanisms it was using otherwise
696: * for the local connection.
697: */
1.31 markus 698: if (!got_data) {
699: u_int32_t rand = 0;
700:
701: strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
702: for (i = 0; i < 16; i++) {
703: if (i % 4 == 0)
704: rand = arc4random();
705: snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
706: rand >>= 8;
707: }
708: }
1.33 markus 709: /*
710: * Got local authentication reasonable information. Request
711: * forwarding with authentication spoofing.
712: */
1.31 markus 713: debug("Requesting X11 forwarding with authentication spoofing.");
714: x11_request_forwarding_with_spoofing(proto, data);
715:
716: /* Read response from the server. */
717: type = packet_read(&plen);
718: if (type == SSH_SMSG_SUCCESS) {
719: forwarded = 1;
720: interactive = 1;
721: } else if (type == SSH_SMSG_FAILURE)
722: log("Warning: Remote host denied X11 forwarding.");
723: else
724: packet_disconnect("Protocol error waiting for X11 forwarding");
725: }
726: /* Tell the packet module whether this is an interactive session. */
727: packet_set_interactive(interactive, options.keepalives);
728:
729: /* Clear agent forwarding if we don\'t have an agent. */
730: authfd = ssh_get_authentication_socket();
731: if (authfd < 0)
732: options.forward_agent = 0;
733: else
734: ssh_close_authentication_socket(authfd);
735:
736: /* Request authentication agent forwarding if appropriate. */
737: if (options.forward_agent) {
738: debug("Requesting authentication agent forwarding.");
739: auth_request_forwarding();
740:
741: /* Read response from the server. */
742: type = packet_read(&plen);
743: packet_integrity_check(plen, 0, type);
744: if (type != SSH_SMSG_SUCCESS)
745: log("Warning: Remote host denied authentication agent forwarding.");
746: }
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(options.local_forwards[i].port,
754: options.local_forwards[i].host,
1.36 markus 755: options.local_forwards[i].host_port,
756: options.gateway_ports);
1.31 markus 757: }
758:
759: /* Initiate remote TCP/IP port forwardings. */
760: for (i = 0; i < options.num_remote_forwards; i++) {
761: debug("Connections to remote port %d forwarded to local address %.200s:%d",
762: options.remote_forwards[i].port,
763: options.remote_forwards[i].host,
764: options.remote_forwards[i].host_port);
765: channel_request_remote_forwarding(options.remote_forwards[i].port,
766: options.remote_forwards[i].host,
767: options.remote_forwards[i].host_port);
768: }
1.34 markus 769:
770: /* If requested, let ssh continue in the background. */
771: if (fork_after_authentication_flag)
772: if (daemon(1, 1) < 0)
773: fatal("daemon() failed: %.200s", strerror(errno));
1.31 markus 774:
1.33 markus 775: /*
776: * If a command was specified on the command line, execute the
777: * command now. Otherwise request the server to start a shell.
778: */
1.31 markus 779: if (buffer_len(&command) > 0) {
780: int len = buffer_len(&command);
781: if (len > 900)
782: len = 900;
783: debug("Sending command: %.*s", len, buffer_ptr(&command));
784: packet_start(SSH_CMSG_EXEC_CMD);
785: packet_put_string(buffer_ptr(&command), buffer_len(&command));
786: packet_send();
787: packet_write_wait();
788: } else {
789: debug("Requesting shell.");
790: packet_start(SSH_CMSG_EXEC_SHELL);
791: packet_send();
792: packet_write_wait();
793: }
794:
795: /* Enter the interactive session. */
1.43 ! markus 796: exit_status = client_loop(have_pty, tty_flag ? options.escape_char : -1);
1.31 markus 797:
798: /* Close the connection to the remote host. */
799: packet_close();
800:
801: /* Exit with the status returned by the program on the remote side. */
802: exit(exit_status);
1.1 deraadt 803: }
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