Annotation of src/usr.bin/ssh/ssh.c, Revision 1.37
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"
1.37 ! markus 14: RCSID("$Id: ssh.c,v 1.36 1999/12/12 19:20:03 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");
96: fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n");
97: fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n");
98: fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
99: fprintf(stderr, " -V Display version number only.\n");
100: fprintf(stderr, " -P Don't allocate a privileged port.\n");
101: fprintf(stderr, " -q Quiet; don't display any warning messages.\n");
102: fprintf(stderr, " -f Fork into background after authentication.\n");
103: fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n");
104:
105: fprintf(stderr, " -c cipher Select encryption algorithm: "
106: "``3des'', "
107: "``blowfish''\n");
108: fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n");
109: fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n");
110: fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n");
111: fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0);
112: fprintf(stderr, " forward them to the other side by connecting to host:port.\n");
113: fprintf(stderr, " -C Enable compression.\n");
114: fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n");
1.37 ! markus 115: fprintf(stderr, " -4 Use IPv4 only.\n");
! 116: fprintf(stderr, " -6 Use IPv6 only.\n");
1.31 markus 117: fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n");
118: exit(1);
1.1 deraadt 119: }
120:
1.32 deraadt 121: /*
122: * Connects to the given host using rsh (or prints an error message and exits
123: * if rsh is not available). This function never returns.
124: */
1.2 provos 125: void
1.31 markus 126: rsh_connect(char *host, char *user, Buffer * command)
1.1 deraadt 127: {
1.31 markus 128: char *args[10];
129: int i;
130:
131: log("Using rsh. WARNING: Connection will not be encrypted.");
132: /* Build argument list for rsh. */
133: i = 0;
134: args[i++] = _PATH_RSH;
135: /* host may have to come after user on some systems */
136: args[i++] = host;
137: if (user) {
138: args[i++] = "-l";
139: args[i++] = user;
140: }
141: if (buffer_len(command) > 0) {
142: buffer_append(command, "\0", 1);
143: args[i++] = buffer_ptr(command);
144: }
145: args[i++] = NULL;
146: if (debug_flag) {
147: for (i = 0; args[i]; i++) {
148: if (i != 0)
149: fprintf(stderr, " ");
150: fprintf(stderr, "%s", args[i]);
151: }
152: fprintf(stderr, "\n");
153: }
154: execv(_PATH_RSH, args);
155: perror(_PATH_RSH);
156: exit(1);
1.1 deraadt 157: }
158:
1.32 deraadt 159: /*
160: * Main program for the ssh client.
161: */
1.2 provos 162: int
163: main(int ac, char **av)
1.1 deraadt 164: {
1.35 markus 165: int i, opt, optind, type, exit_status, ok, authfd;
166: u_short fwd_port, fwd_host_port;
1.31 markus 167: char *optarg, *cp, buf[256];
168: Buffer command;
169: struct winsize ws;
170: struct stat st;
171: struct passwd *pw, pwcopy;
172: int interactive = 0, dummy;
173: uid_t original_effective_uid;
174: int plen;
175:
1.33 markus 176: /*
177: * Save the original real uid. It will be needed later (uid-swapping
178: * may clobber the real uid).
179: */
1.31 markus 180: original_real_uid = getuid();
181: original_effective_uid = geteuid();
182:
183: /* If we are installed setuid root be careful to not drop core. */
184: if (original_real_uid != original_effective_uid) {
185: struct rlimit rlim;
186: rlim.rlim_cur = rlim.rlim_max = 0;
187: if (setrlimit(RLIMIT_CORE, &rlim) < 0)
188: fatal("setrlimit failed: %.100s", strerror(errno));
1.1 deraadt 189: }
1.33 markus 190: /*
191: * Use uid-swapping to give up root privileges for the duration of
192: * option processing. We will re-instantiate the rights when we are
193: * ready to create the privileged port, and will permanently drop
194: * them when the port has been created (actually, when the connection
195: * has been made, as we may need to create the port several times).
196: */
1.31 markus 197: temporarily_use_uid(original_real_uid);
198:
1.33 markus 199: /*
200: * Set our umask to something reasonable, as some files are created
201: * with the default umask. This will make them world-readable but
202: * writable only by the owner, which is ok for all files for which we
203: * don't set the modes explicitly.
204: */
1.31 markus 205: umask(022);
206:
207: /* Save our own name. */
208: av0 = av[0];
209:
210: /* Initialize option structure to indicate that no values have been set. */
211: initialize_options(&options);
212:
213: /* Parse command-line arguments. */
214: host = NULL;
215:
216: /* If program name is not one of the standard names, use it as host name. */
217: if (strchr(av0, '/'))
218: cp = strrchr(av0, '/') + 1;
219: else
220: cp = av0;
221: if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 &&
222: strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0)
223: host = cp;
224:
225: for (optind = 1; optind < ac; optind++) {
226: if (av[optind][0] != '-') {
227: if (host)
228: break;
229: if ((cp = strchr(av[optind], '@'))) {
230: options.user = av[optind];
231: *cp = '\0';
232: host = ++cp;
233: } else
234: host = av[optind];
235: continue;
236: }
237: opt = av[optind][1];
238: if (!opt)
239: usage();
240: if (strchr("eilcpLRo", opt)) { /* options with arguments */
241: optarg = av[optind] + 2;
242: if (strcmp(optarg, "") == 0) {
243: if (optind >= ac - 1)
244: usage();
245: optarg = av[++optind];
246: }
247: } else {
248: if (av[optind][2])
249: usage();
250: optarg = NULL;
251: }
252: switch (opt) {
1.37 ! markus 253: case '4':
! 254: IPv4or6 = AF_INET;
! 255: break;
! 256:
! 257: case '6':
! 258: IPv4or6 = AF_INET6;
! 259: break;
! 260:
1.31 markus 261: case 'n':
262: stdin_null_flag = 1;
263: break;
264:
265: case 'f':
266: fork_after_authentication_flag = 1;
267: stdin_null_flag = 1;
268: break;
269:
270: case 'x':
271: options.forward_x11 = 0;
272: break;
273:
274: case 'X':
275: options.forward_x11 = 1;
276: break;
277:
278: case 'g':
279: options.gateway_ports = 1;
280: break;
281:
282: case 'P':
283: options.use_privileged_port = 0;
284: break;
285:
286: case 'a':
287: options.forward_agent = 0;
288: break;
1.9 dugsong 289: #ifdef AFS
1.31 markus 290: case 'k':
291: options.kerberos_tgt_passing = 0;
292: options.afs_token_passing = 0;
293: break;
1.1 deraadt 294: #endif
1.31 markus 295: case 'i':
296: if (stat(optarg, &st) < 0) {
297: fprintf(stderr, "Warning: Identity file %s does not exist.\n",
298: optarg);
299: break;
300: }
301: if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES)
302: fatal("Too many identity files specified (max %d)",
303: SSH_MAX_IDENTITY_FILES);
304: options.identity_files[options.num_identity_files++] =
305: xstrdup(optarg);
306: break;
307:
308: case 't':
309: tty_flag = 1;
310: break;
311:
312: case 'v':
313: case 'V':
314: fprintf(stderr, "SSH Version %s, protocol version %d.%d.\n",
315: SSH_VERSION, PROTOCOL_MAJOR, PROTOCOL_MINOR);
316: fprintf(stderr, "Compiled with SSL.\n");
317: if (opt == 'V')
318: exit(0);
319: debug_flag = 1;
320: options.log_level = SYSLOG_LEVEL_DEBUG;
321: break;
322:
323: case 'q':
324: options.log_level = SYSLOG_LEVEL_QUIET;
325: break;
326:
327: case 'e':
328: if (optarg[0] == '^' && optarg[2] == 0 &&
329: (unsigned char) optarg[1] >= 64 && (unsigned char) optarg[1] < 128)
330: options.escape_char = (unsigned char) optarg[1] & 31;
331: else if (strlen(optarg) == 1)
332: options.escape_char = (unsigned char) optarg[0];
333: else if (strcmp(optarg, "none") == 0)
334: options.escape_char = -2;
335: else {
336: fprintf(stderr, "Bad escape character '%s'.\n", optarg);
337: exit(1);
338: }
339: break;
340:
341: case 'c':
342: options.cipher = cipher_number(optarg);
343: if (options.cipher == -1) {
344: fprintf(stderr, "Unknown cipher type '%s'\n", optarg);
345: exit(1);
346: }
347: break;
348:
349: case 'p':
350: options.port = atoi(optarg);
351: break;
352:
353: case 'l':
354: options.user = optarg;
355: break;
356:
357: case 'R':
1.37 ! markus 358: if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
! 359: &fwd_host_port) != 3 &&
! 360: sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
! 361: &fwd_host_port) != 3) {
1.31 markus 362: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
363: usage();
364: /* NOTREACHED */
365: }
366: add_remote_forward(&options, fwd_port, buf, fwd_host_port);
367: break;
368:
369: case 'L':
1.37 ! markus 370: if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
! 371: &fwd_host_port) != 3 &&
! 372: sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
! 373: &fwd_host_port) != 3) {
1.31 markus 374: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
375: usage();
376: /* NOTREACHED */
377: }
378: add_local_forward(&options, fwd_port, buf, fwd_host_port);
379: break;
380:
381: case 'C':
382: options.compression = 1;
383: break;
384:
385: case 'o':
386: dummy = 1;
387: if (process_config_line(&options, host ? host : "", optarg,
388: "command-line", 0, &dummy) != 0)
389: exit(1);
390: break;
391:
392: default:
393: usage();
1.1 deraadt 394: }
1.31 markus 395: }
396:
397: /* Check that we got a host name. */
398: if (!host)
399: usage();
400:
401: /* check if RSA support exists */
402: if (rsa_alive() == 0) {
403: extern char *__progname;
404:
405: fprintf(stderr,
406: "%s: no RSA support in libssl and libcrypto. See ssl(8).\n",
407: __progname);
408: exit(1);
409: }
410: /* Initialize the command to execute on remote host. */
411: buffer_init(&command);
1.1 deraadt 412:
1.33 markus 413: /*
414: * Save the command to execute on the remote host in a buffer. There
415: * is no limit on the length of the command, except by the maximum
416: * packet size. Also sets the tty flag if there is no command.
417: */
1.31 markus 418: if (optind == ac) {
419: /* No command specified - execute shell on a tty. */
420: tty_flag = 1;
421: } else {
422: /* A command has been specified. Store it into the
423: buffer. */
424: for (i = optind; i < ac; i++) {
425: if (i > optind)
426: buffer_append(&command, " ", 1);
427: buffer_append(&command, av[i], strlen(av[i]));
428: }
429: }
430:
431: /* Cannot fork to background if no command. */
432: if (fork_after_authentication_flag && buffer_len(&command) == 0)
433: fatal("Cannot fork into background without a command to execute.");
434:
435: /* Allocate a tty by default if no command specified. */
436: if (buffer_len(&command) == 0)
437: tty_flag = 1;
438:
439: /* Do not allocate a tty if stdin is not a tty. */
440: if (!isatty(fileno(stdin))) {
441: if (tty_flag)
442: fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n");
443: tty_flag = 0;
444: }
445: /* Get user data. */
446: pw = getpwuid(original_real_uid);
447: if (!pw) {
448: fprintf(stderr, "You don't exist, go away!\n");
449: exit(1);
450: }
451: /* Take a copy of the returned structure. */
452: memset(&pwcopy, 0, sizeof(pwcopy));
453: pwcopy.pw_name = xstrdup(pw->pw_name);
454: pwcopy.pw_passwd = xstrdup(pw->pw_passwd);
455: pwcopy.pw_uid = pw->pw_uid;
456: pwcopy.pw_gid = pw->pw_gid;
457: pwcopy.pw_dir = xstrdup(pw->pw_dir);
458: pwcopy.pw_shell = xstrdup(pw->pw_shell);
459: pw = &pwcopy;
460:
461: /* Initialize "log" output. Since we are the client all output
462: actually goes to the terminal. */
463: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
464:
465: /* Read per-user configuration file. */
466: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE);
467: read_config_file(buf, host, &options);
468:
469: /* Read systemwide configuration file. */
470: read_config_file(HOST_CONFIG_FILE, host, &options);
471:
472: /* Fill configuration defaults. */
473: fill_default_options(&options);
474:
475: /* reinit */
476: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
477:
478: if (options.user == NULL)
479: options.user = xstrdup(pw->pw_name);
480:
481: if (options.hostname != NULL)
482: host = options.hostname;
483:
484: /* Find canonic host name. */
485: if (strchr(host, '.') == 0) {
1.37 ! markus 486: struct addrinfo hints;
! 487: struct addrinfo *ai = NULL;
! 488: int errgai;
! 489: memset(&hints, 0, sizeof(hints));
! 490: hints.ai_family = AF_UNSPEC;
! 491: hints.ai_flags = AI_CANONNAME;
! 492: errgai = getaddrinfo(host, NULL, &hints, &ai);
! 493: if (errgai == 0) {
! 494: if (ai->ai_canonname != NULL)
! 495: host = xstrdup(ai->ai_canonname);
! 496: freeaddrinfo(ai);
1.31 markus 497: }
498: }
499: /* Disable rhosts authentication if not running as root. */
500: if (original_effective_uid != 0 || !options.use_privileged_port) {
501: options.rhosts_authentication = 0;
502: options.rhosts_rsa_authentication = 0;
503: }
1.33 markus 504: /*
505: * If using rsh has been selected, exec it now (without trying
506: * anything else). Note that we must release privileges first.
507: */
1.31 markus 508: if (options.use_rsh) {
1.33 markus 509: /*
510: * Restore our superuser privileges. This must be done
511: * before permanently setting the uid.
512: */
1.31 markus 513: restore_uid();
514:
515: /* Switch to the original uid permanently. */
516: permanently_set_uid(original_real_uid);
517:
518: /* Execute rsh. */
519: rsh_connect(host, options.user, &command);
520: fatal("rsh_connect returned");
521: }
522: /* Restore our superuser privileges. */
523: restore_uid();
524:
1.33 markus 525: /*
526: * Open a connection to the remote host. This needs root privileges
527: * if rhosts_{rsa_}authentication is enabled.
528: */
1.31 markus 529:
530: ok = ssh_connect(host, &hostaddr, options.port,
531: options.connection_attempts,
532: !options.rhosts_authentication &&
533: !options.rhosts_rsa_authentication,
534: original_real_uid,
535: options.proxy_command);
536:
1.33 markus 537: /*
538: * If we successfully made the connection, load the host private key
539: * in case we will need it later for combined rsa-rhosts
540: * authentication. This must be done before releasing extra
541: * privileges, because the file is only readable by root.
542: */
1.31 markus 543: if (ok) {
544: host_private_key = RSA_new();
545: if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL))
546: host_private_key_loaded = 1;
547: }
1.33 markus 548: /*
549: * Get rid of any extra privileges that we may have. We will no
550: * longer need them. Also, extra privileges could make it very hard
551: * to read identity files and other non-world-readable files from the
552: * user's home directory if it happens to be on a NFS volume where
553: * root is mapped to nobody.
554: */
555:
556: /*
557: * Note that some legacy systems need to postpone the following call
558: * to permanently_set_uid() until the private hostkey is destroyed
559: * with RSA_free(). Otherwise the calling user could ptrace() the
560: * process, read the private hostkey and impersonate the host.
561: * OpenBSD does not allow ptracing of setuid processes.
562: */
1.31 markus 563: permanently_set_uid(original_real_uid);
564:
1.33 markus 565: /*
566: * Now that we are back to our own permissions, create ~/.ssh
567: * directory if it doesn\'t already exist.
568: */
1.31 markus 569: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR);
570: if (stat(buf, &st) < 0)
571: if (mkdir(buf, 0755) < 0)
572: error("Could not create directory '%.200s'.", buf);
573:
574: /* Check if the connection failed, and try "rsh" if appropriate. */
575: if (!ok) {
576: if (options.port != 0)
1.35 markus 577: log("Secure connection to %.100s on port %hu refused%.100s.",
1.31 markus 578: host, options.port,
579: options.fallback_to_rsh ? "; reverting to insecure method" : "");
580: else
581: log("Secure connection to %.100s refused%.100s.", host,
582: options.fallback_to_rsh ? "; reverting to insecure method" : "");
583:
584: if (options.fallback_to_rsh) {
585: rsh_connect(host, options.user, &command);
586: fatal("rsh_connect returned");
587: }
588: exit(1);
589: }
590: /* Expand ~ in options.identity_files. */
591: for (i = 0; i < options.num_identity_files; i++)
592: options.identity_files[i] =
593: tilde_expand_filename(options.identity_files[i], original_real_uid);
594:
595: /* Expand ~ in known host file names. */
596: options.system_hostfile = tilde_expand_filename(options.system_hostfile,
597: original_real_uid);
598: options.user_hostfile = tilde_expand_filename(options.user_hostfile,
599: original_real_uid);
600:
601: /* Log into the remote system. This never returns if the login fails. */
602: ssh_login(host_private_key_loaded, host_private_key,
1.37 ! markus 603: host, (struct sockaddr *)&hostaddr, original_real_uid);
1.31 markus 604:
605: /* We no longer need the host private key. Clear it now. */
606: if (host_private_key_loaded)
607: RSA_free(host_private_key); /* Destroys contents safely */
608:
609: /* Close connection cleanly after attack. */
610: cipher_attack_detected = packet_disconnect;
611:
612: /* Enable compression if requested. */
613: if (options.compression) {
614: debug("Requesting compression at level %d.", options.compression_level);
615:
616: if (options.compression_level < 1 || options.compression_level > 9)
617: fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
618:
619: /* Send the request. */
620: packet_start(SSH_CMSG_REQUEST_COMPRESSION);
621: packet_put_int(options.compression_level);
622: packet_send();
623: packet_write_wait();
624: type = packet_read(&plen);
625: if (type == SSH_SMSG_SUCCESS)
626: packet_start_compression(options.compression_level);
627: else if (type == SSH_SMSG_FAILURE)
628: log("Warning: Remote host refused compression.");
629: else
630: packet_disconnect("Protocol error waiting for compression response.");
631: }
632: /* Allocate a pseudo tty if appropriate. */
633: if (tty_flag) {
634: debug("Requesting pty.");
635:
636: /* Start the packet. */
637: packet_start(SSH_CMSG_REQUEST_PTY);
638:
639: /* Store TERM in the packet. There is no limit on the
640: length of the string. */
641: cp = getenv("TERM");
642: if (!cp)
643: cp = "";
644: packet_put_string(cp, strlen(cp));
645:
646: /* Store window size in the packet. */
647: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
648: memset(&ws, 0, sizeof(ws));
649: packet_put_int(ws.ws_row);
650: packet_put_int(ws.ws_col);
651: packet_put_int(ws.ws_xpixel);
652: packet_put_int(ws.ws_ypixel);
653:
654: /* Store tty modes in the packet. */
655: tty_make_modes(fileno(stdin));
656:
657: /* Send the packet, and wait for it to leave. */
658: packet_send();
659: packet_write_wait();
660:
661: /* Read response from the server. */
662: type = packet_read(&plen);
663: if (type == SSH_SMSG_SUCCESS)
664: interactive = 1;
665: else if (type == SSH_SMSG_FAILURE)
666: log("Warning: Remote host failed or refused to allocate a pseudo tty.");
667: else
668: packet_disconnect("Protocol error waiting for pty request response.");
669: }
670: /* Request X11 forwarding if enabled and DISPLAY is set. */
671: if (options.forward_x11 && getenv("DISPLAY") != NULL) {
672: char line[512], proto[512], data[512];
673: FILE *f;
674: int forwarded = 0, got_data = 0, i;
1.1 deraadt 675:
676: #ifdef XAUTH_PATH
1.31 markus 677: /* Try to get Xauthority information for the display. */
678: snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null",
679: XAUTH_PATH, getenv("DISPLAY"));
680: f = popen(line, "r");
681: if (f && fgets(line, sizeof(line), f) &&
682: sscanf(line, "%*s %s %s", proto, data) == 2)
683: got_data = 1;
684: if (f)
685: pclose(f);
1.1 deraadt 686: #endif /* XAUTH_PATH */
1.33 markus 687: /*
688: * If we didn't get authentication data, just make up some
689: * data. The forwarding code will check the validity of the
690: * response anyway, and substitute this data. The X11
691: * server, however, will ignore this fake data and use
692: * whatever authentication mechanisms it was using otherwise
693: * for the local connection.
694: */
1.31 markus 695: if (!got_data) {
696: u_int32_t rand = 0;
697:
698: strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
699: for (i = 0; i < 16; i++) {
700: if (i % 4 == 0)
701: rand = arc4random();
702: snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
703: rand >>= 8;
704: }
705: }
1.33 markus 706: /*
707: * Got local authentication reasonable information. Request
708: * forwarding with authentication spoofing.
709: */
1.31 markus 710: debug("Requesting X11 forwarding with authentication spoofing.");
711: x11_request_forwarding_with_spoofing(proto, data);
712:
713: /* Read response from the server. */
714: type = packet_read(&plen);
715: if (type == SSH_SMSG_SUCCESS) {
716: forwarded = 1;
717: interactive = 1;
718: } else if (type == SSH_SMSG_FAILURE)
719: log("Warning: Remote host denied X11 forwarding.");
720: else
721: packet_disconnect("Protocol error waiting for X11 forwarding");
722: }
723: /* Tell the packet module whether this is an interactive session. */
724: packet_set_interactive(interactive, options.keepalives);
725:
726: /* Clear agent forwarding if we don\'t have an agent. */
727: authfd = ssh_get_authentication_socket();
728: if (authfd < 0)
729: options.forward_agent = 0;
730: else
731: ssh_close_authentication_socket(authfd);
732:
733: /* Request authentication agent forwarding if appropriate. */
734: if (options.forward_agent) {
735: debug("Requesting authentication agent forwarding.");
736: auth_request_forwarding();
737:
738: /* Read response from the server. */
739: type = packet_read(&plen);
740: packet_integrity_check(plen, 0, type);
741: if (type != SSH_SMSG_SUCCESS)
742: log("Warning: Remote host denied authentication agent forwarding.");
743: }
744: /* Initiate local TCP/IP port forwardings. */
745: for (i = 0; i < options.num_local_forwards; i++) {
746: debug("Connections to local port %d forwarded to remote address %.200s:%d",
747: options.local_forwards[i].port,
748: options.local_forwards[i].host,
749: options.local_forwards[i].host_port);
750: channel_request_local_forwarding(options.local_forwards[i].port,
751: options.local_forwards[i].host,
1.36 markus 752: options.local_forwards[i].host_port,
753: options.gateway_ports);
1.31 markus 754: }
755:
756: /* Initiate remote TCP/IP port forwardings. */
757: for (i = 0; i < options.num_remote_forwards; i++) {
758: debug("Connections to remote port %d forwarded to local address %.200s:%d",
759: options.remote_forwards[i].port,
760: options.remote_forwards[i].host,
761: options.remote_forwards[i].host_port);
762: channel_request_remote_forwarding(options.remote_forwards[i].port,
763: options.remote_forwards[i].host,
764: options.remote_forwards[i].host_port);
765: }
1.34 markus 766:
767: /* If requested, let ssh continue in the background. */
768: if (fork_after_authentication_flag)
769: if (daemon(1, 1) < 0)
770: fatal("daemon() failed: %.200s", strerror(errno));
1.31 markus 771:
1.33 markus 772: /*
773: * If a command was specified on the command line, execute the
774: * command now. Otherwise request the server to start a shell.
775: */
1.31 markus 776: if (buffer_len(&command) > 0) {
777: int len = buffer_len(&command);
778: if (len > 900)
779: len = 900;
780: debug("Sending command: %.*s", len, buffer_ptr(&command));
781: packet_start(SSH_CMSG_EXEC_CMD);
782: packet_put_string(buffer_ptr(&command), buffer_len(&command));
783: packet_send();
784: packet_write_wait();
785: } else {
786: debug("Requesting shell.");
787: packet_start(SSH_CMSG_EXEC_SHELL);
788: packet_send();
789: packet_write_wait();
790: }
791:
792: /* Enter the interactive session. */
793: exit_status = client_loop(tty_flag, tty_flag ? options.escape_char : -1);
794:
795: /* Close the connection to the remote host. */
796: packet_close();
797:
798: /* Exit with the status returned by the program on the remote side. */
799: exit(exit_status);
1.1 deraadt 800: }
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