Annotation of src/usr.bin/ssh/ssh.c, Revision 1.44
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"
1.44 ! markus 14: RCSID("$Id: ssh.c,v 1.43 2000/03/23 21:52:02 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"
1.44 ! markus 23: #include "channels.h"
1.1 deraadt 24:
1.37 markus 25: /* Flag indicating whether IPv4 or IPv6. This can be set on the command line.
26: Default value is AF_UNSPEC means both IPv4 and IPv6. */
27: int IPv4or6 = AF_UNSPEC;
28:
1.31 markus 29: /* Flag indicating whether debug mode is on. This can be set on the command line. */
1.1 deraadt 30: int debug_flag = 0;
31:
32: int tty_flag = 0;
33:
1.33 markus 34: /*
35: * Flag indicating that nothing should be read from stdin. This can be set
36: * on the command line.
37: */
1.1 deraadt 38: int stdin_null_flag = 0;
39:
1.33 markus 40: /*
41: * Flag indicating that ssh should fork after authentication. This is useful
42: * so that the pasphrase can be entered manually, and then ssh goes to the
43: * background.
44: */
1.1 deraadt 45: int fork_after_authentication_flag = 0;
46:
1.33 markus 47: /*
48: * General data structure for command line options and options configurable
49: * in configuration files. See readconf.h.
50: */
1.1 deraadt 51: Options options;
52:
1.33 markus 53: /*
54: * Name of the host we are connecting to. This is the name given on the
55: * command line, or the HostName specified for the user-supplied name in a
56: * configuration file.
57: */
1.1 deraadt 58: char *host;
59:
1.22 provos 60: /* socket address the host resolves to */
1.37 markus 61: struct sockaddr_storage hostaddr;
1.22 provos 62:
1.33 markus 63: /*
64: * Flag to indicate that we have received a window change signal which has
65: * not yet been processed. This will cause a message indicating the new
66: * window size to be sent to the server a little later. This is volatile
67: * because this is updated in a signal handler.
68: */
1.1 deraadt 69: volatile int received_window_change_signal = 0;
70:
71: /* Value of argv[0] (set in the main program). */
72: char *av0;
73:
74: /* Flag indicating whether we have a valid host private key loaded. */
75: int host_private_key_loaded = 0;
76:
77: /* Host private key. */
1.2 provos 78: RSA *host_private_key = NULL;
1.1 deraadt 79:
1.10 dugsong 80: /* Original real UID. */
81: uid_t original_real_uid;
1.1 deraadt 82:
83: /* Prints a help message to the user. This function never returns. */
84:
1.2 provos 85: void
86: usage()
1.1 deraadt 87: {
1.31 markus 88: fprintf(stderr, "Usage: %s [options] host [command]\n", av0);
89: fprintf(stderr, "Options:\n");
90: fprintf(stderr, " -l user Log in using this user name.\n");
91: fprintf(stderr, " -n Redirect input from /dev/null.\n");
92: fprintf(stderr, " -a Disable authentication agent forwarding.\n");
1.9 dugsong 93: #ifdef AFS
1.31 markus 94: fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n");
95: #endif /* AFS */
96: fprintf(stderr, " -x Disable X11 connection forwarding.\n");
1.41 markus 97: fprintf(stderr, " -X Enable X11 connection forwarding.\n");
1.31 markus 98: fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n");
99: fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n");
100: fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
101: fprintf(stderr, " -V Display version number only.\n");
102: fprintf(stderr, " -P Don't allocate a privileged port.\n");
103: fprintf(stderr, " -q Quiet; don't display any warning messages.\n");
104: fprintf(stderr, " -f Fork into background after authentication.\n");
105: fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n");
106:
107: fprintf(stderr, " -c cipher Select encryption algorithm: "
108: "``3des'', "
109: "``blowfish''\n");
110: fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n");
111: fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n");
112: fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n");
113: fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0);
114: fprintf(stderr, " forward them to the other side by connecting to host:port.\n");
115: fprintf(stderr, " -C Enable compression.\n");
116: fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n");
1.37 markus 117: fprintf(stderr, " -4 Use IPv4 only.\n");
118: fprintf(stderr, " -6 Use IPv6 only.\n");
1.31 markus 119: fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n");
120: exit(1);
1.1 deraadt 121: }
122:
1.32 deraadt 123: /*
124: * Connects to the given host using rsh (or prints an error message and exits
125: * if rsh is not available). This function never returns.
126: */
1.2 provos 127: void
1.31 markus 128: rsh_connect(char *host, char *user, Buffer * command)
1.1 deraadt 129: {
1.31 markus 130: char *args[10];
131: int i;
132:
133: log("Using rsh. WARNING: Connection will not be encrypted.");
134: /* Build argument list for rsh. */
135: i = 0;
136: args[i++] = _PATH_RSH;
137: /* host may have to come after user on some systems */
138: args[i++] = host;
139: if (user) {
140: args[i++] = "-l";
141: args[i++] = user;
142: }
143: if (buffer_len(command) > 0) {
144: buffer_append(command, "\0", 1);
145: args[i++] = buffer_ptr(command);
146: }
147: args[i++] = NULL;
148: if (debug_flag) {
149: for (i = 0; args[i]; i++) {
150: if (i != 0)
151: fprintf(stderr, " ");
152: fprintf(stderr, "%s", args[i]);
153: }
154: fprintf(stderr, "\n");
155: }
156: execv(_PATH_RSH, args);
157: perror(_PATH_RSH);
158: exit(1);
1.1 deraadt 159: }
160:
1.32 deraadt 161: /*
162: * Main program for the ssh client.
163: */
1.2 provos 164: int
165: main(int ac, char **av)
1.1 deraadt 166: {
1.35 markus 167: int i, opt, optind, type, exit_status, ok, authfd;
168: u_short fwd_port, fwd_host_port;
1.31 markus 169: char *optarg, *cp, buf[256];
170: Buffer command;
171: struct winsize ws;
172: struct stat st;
173: struct passwd *pw, pwcopy;
174: int interactive = 0, dummy;
1.43 markus 175: int have_pty = 0;
1.31 markus 176: uid_t original_effective_uid;
177: int plen;
178:
1.33 markus 179: /*
180: * Save the original real uid. It will be needed later (uid-swapping
181: * may clobber the real uid).
182: */
1.31 markus 183: original_real_uid = getuid();
184: original_effective_uid = geteuid();
185:
186: /* If we are installed setuid root be careful to not drop core. */
187: if (original_real_uid != original_effective_uid) {
188: struct rlimit rlim;
189: rlim.rlim_cur = rlim.rlim_max = 0;
190: if (setrlimit(RLIMIT_CORE, &rlim) < 0)
191: fatal("setrlimit failed: %.100s", strerror(errno));
1.1 deraadt 192: }
1.33 markus 193: /*
194: * Use uid-swapping to give up root privileges for the duration of
195: * option processing. We will re-instantiate the rights when we are
196: * ready to create the privileged port, and will permanently drop
197: * them when the port has been created (actually, when the connection
198: * has been made, as we may need to create the port several times).
199: */
1.31 markus 200: temporarily_use_uid(original_real_uid);
201:
1.33 markus 202: /*
203: * Set our umask to something reasonable, as some files are created
204: * with the default umask. This will make them world-readable but
205: * writable only by the owner, which is ok for all files for which we
206: * don't set the modes explicitly.
207: */
1.31 markus 208: umask(022);
209:
210: /* Save our own name. */
211: av0 = av[0];
212:
213: /* Initialize option structure to indicate that no values have been set. */
214: initialize_options(&options);
215:
216: /* Parse command-line arguments. */
217: host = NULL;
218:
219: /* If program name is not one of the standard names, use it as host name. */
220: if (strchr(av0, '/'))
221: cp = strrchr(av0, '/') + 1;
222: else
223: cp = av0;
224: if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 &&
225: strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0)
226: host = cp;
227:
228: for (optind = 1; optind < ac; optind++) {
229: if (av[optind][0] != '-') {
230: if (host)
231: break;
232: if ((cp = strchr(av[optind], '@'))) {
1.38 markus 233: if(cp == av[optind])
234: usage();
1.31 markus 235: options.user = av[optind];
236: *cp = '\0';
237: host = ++cp;
238: } else
239: host = av[optind];
240: continue;
241: }
242: opt = av[optind][1];
243: if (!opt)
244: usage();
245: if (strchr("eilcpLRo", opt)) { /* options with arguments */
246: optarg = av[optind] + 2;
247: if (strcmp(optarg, "") == 0) {
248: if (optind >= ac - 1)
249: usage();
250: optarg = av[++optind];
251: }
252: } else {
253: if (av[optind][2])
254: usage();
255: optarg = NULL;
256: }
257: switch (opt) {
1.37 markus 258: case '4':
259: IPv4or6 = AF_INET;
260: break;
261:
262: case '6':
263: IPv4or6 = AF_INET6;
264: break;
265:
1.31 markus 266: case 'n':
267: stdin_null_flag = 1;
268: break;
269:
270: case 'f':
271: fork_after_authentication_flag = 1;
272: stdin_null_flag = 1;
273: break;
274:
275: case 'x':
276: options.forward_x11 = 0;
277: break;
278:
279: case 'X':
280: options.forward_x11 = 1;
281: break;
282:
283: case 'g':
284: options.gateway_ports = 1;
285: break;
286:
287: case 'P':
288: options.use_privileged_port = 0;
289: break;
290:
291: case 'a':
292: options.forward_agent = 0;
293: break;
1.9 dugsong 294: #ifdef AFS
1.31 markus 295: case 'k':
296: options.kerberos_tgt_passing = 0;
297: options.afs_token_passing = 0;
298: break;
1.1 deraadt 299: #endif
1.31 markus 300: case 'i':
301: if (stat(optarg, &st) < 0) {
302: fprintf(stderr, "Warning: Identity file %s does not exist.\n",
303: optarg);
304: break;
305: }
306: if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES)
307: fatal("Too many identity files specified (max %d)",
308: SSH_MAX_IDENTITY_FILES);
309: options.identity_files[options.num_identity_files++] =
310: xstrdup(optarg);
311: break;
312:
313: case 't':
314: tty_flag = 1;
315: break;
316:
317: case 'v':
318: case 'V':
319: fprintf(stderr, "SSH Version %s, protocol version %d.%d.\n",
320: SSH_VERSION, PROTOCOL_MAJOR, PROTOCOL_MINOR);
321: fprintf(stderr, "Compiled with SSL.\n");
322: if (opt == 'V')
323: exit(0);
324: debug_flag = 1;
325: options.log_level = SYSLOG_LEVEL_DEBUG;
326: break;
327:
328: case 'q':
329: options.log_level = SYSLOG_LEVEL_QUIET;
330: break;
331:
332: case 'e':
333: if (optarg[0] == '^' && optarg[2] == 0 &&
334: (unsigned char) optarg[1] >= 64 && (unsigned char) optarg[1] < 128)
335: options.escape_char = (unsigned char) optarg[1] & 31;
336: else if (strlen(optarg) == 1)
337: options.escape_char = (unsigned char) optarg[0];
338: else if (strcmp(optarg, "none") == 0)
339: options.escape_char = -2;
340: else {
341: fprintf(stderr, "Bad escape character '%s'.\n", optarg);
342: exit(1);
343: }
344: break;
345:
346: case 'c':
347: options.cipher = cipher_number(optarg);
348: if (options.cipher == -1) {
349: fprintf(stderr, "Unknown cipher type '%s'\n", optarg);
350: exit(1);
351: }
352: break;
353:
354: case 'p':
355: options.port = atoi(optarg);
356: break;
357:
358: case 'l':
359: options.user = optarg;
360: break;
361:
362: case 'R':
1.37 markus 363: if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
364: &fwd_host_port) != 3 &&
365: sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
366: &fwd_host_port) != 3) {
1.31 markus 367: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
368: usage();
369: /* NOTREACHED */
370: }
371: add_remote_forward(&options, fwd_port, buf, fwd_host_port);
372: break;
373:
374: case 'L':
1.37 markus 375: if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
376: &fwd_host_port) != 3 &&
377: sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
378: &fwd_host_port) != 3) {
1.31 markus 379: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
380: usage();
381: /* NOTREACHED */
382: }
383: add_local_forward(&options, fwd_port, buf, fwd_host_port);
384: break;
385:
386: case 'C':
387: options.compression = 1;
388: break;
389:
390: case 'o':
391: dummy = 1;
392: if (process_config_line(&options, host ? host : "", optarg,
393: "command-line", 0, &dummy) != 0)
394: exit(1);
395: break;
396:
397: default:
398: usage();
1.1 deraadt 399: }
1.31 markus 400: }
401:
402: /* Check that we got a host name. */
403: if (!host)
404: usage();
405:
406: /* check if RSA support exists */
407: if (rsa_alive() == 0) {
408: extern char *__progname;
409:
410: fprintf(stderr,
411: "%s: no RSA support in libssl and libcrypto. See ssl(8).\n",
412: __progname);
413: exit(1);
414: }
415: /* Initialize the command to execute on remote host. */
416: buffer_init(&command);
1.1 deraadt 417:
1.33 markus 418: /*
419: * Save the command to execute on the remote host in a buffer. There
420: * is no limit on the length of the command, except by the maximum
421: * packet size. Also sets the tty flag if there is no command.
422: */
1.31 markus 423: if (optind == ac) {
424: /* No command specified - execute shell on a tty. */
425: tty_flag = 1;
426: } else {
427: /* A command has been specified. Store it into the
428: buffer. */
429: for (i = optind; i < ac; i++) {
430: if (i > optind)
431: buffer_append(&command, " ", 1);
432: buffer_append(&command, av[i], strlen(av[i]));
433: }
434: }
435:
436: /* Cannot fork to background if no command. */
437: if (fork_after_authentication_flag && buffer_len(&command) == 0)
438: fatal("Cannot fork into background without a command to execute.");
439:
440: /* Allocate a tty by default if no command specified. */
441: if (buffer_len(&command) == 0)
442: tty_flag = 1;
443:
444: /* Do not allocate a tty if stdin is not a tty. */
445: if (!isatty(fileno(stdin))) {
446: if (tty_flag)
447: fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n");
448: tty_flag = 0;
449: }
450: /* Get user data. */
451: pw = getpwuid(original_real_uid);
452: if (!pw) {
453: fprintf(stderr, "You don't exist, go away!\n");
454: exit(1);
455: }
456: /* Take a copy of the returned structure. */
457: memset(&pwcopy, 0, sizeof(pwcopy));
458: pwcopy.pw_name = xstrdup(pw->pw_name);
459: pwcopy.pw_passwd = xstrdup(pw->pw_passwd);
460: pwcopy.pw_uid = pw->pw_uid;
461: pwcopy.pw_gid = pw->pw_gid;
462: pwcopy.pw_dir = xstrdup(pw->pw_dir);
463: pwcopy.pw_shell = xstrdup(pw->pw_shell);
464: pw = &pwcopy;
465:
466: /* Initialize "log" output. Since we are the client all output
467: actually goes to the terminal. */
468: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
469:
470: /* Read per-user configuration file. */
471: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE);
472: read_config_file(buf, host, &options);
473:
474: /* Read systemwide configuration file. */
475: read_config_file(HOST_CONFIG_FILE, host, &options);
476:
477: /* Fill configuration defaults. */
478: fill_default_options(&options);
479:
480: /* reinit */
481: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
482:
483: if (options.user == NULL)
484: options.user = xstrdup(pw->pw_name);
485:
486: if (options.hostname != NULL)
487: host = options.hostname;
488:
489: /* Find canonic host name. */
490: if (strchr(host, '.') == 0) {
1.37 markus 491: struct addrinfo hints;
492: struct addrinfo *ai = NULL;
493: int errgai;
494: memset(&hints, 0, sizeof(hints));
1.40 markus 495: hints.ai_family = IPv4or6;
1.37 markus 496: hints.ai_flags = AI_CANONNAME;
1.39 markus 497: hints.ai_socktype = SOCK_STREAM;
1.37 markus 498: errgai = getaddrinfo(host, NULL, &hints, &ai);
499: if (errgai == 0) {
500: if (ai->ai_canonname != NULL)
501: host = xstrdup(ai->ai_canonname);
502: freeaddrinfo(ai);
1.31 markus 503: }
504: }
505: /* Disable rhosts authentication if not running as root. */
506: if (original_effective_uid != 0 || !options.use_privileged_port) {
507: options.rhosts_authentication = 0;
508: options.rhosts_rsa_authentication = 0;
509: }
1.33 markus 510: /*
511: * If using rsh has been selected, exec it now (without trying
512: * anything else). Note that we must release privileges first.
513: */
1.31 markus 514: if (options.use_rsh) {
1.33 markus 515: /*
516: * Restore our superuser privileges. This must be done
517: * before permanently setting the uid.
518: */
1.31 markus 519: restore_uid();
520:
521: /* Switch to the original uid permanently. */
522: permanently_set_uid(original_real_uid);
523:
524: /* Execute rsh. */
525: rsh_connect(host, options.user, &command);
526: fatal("rsh_connect returned");
527: }
528: /* Restore our superuser privileges. */
529: restore_uid();
530:
1.33 markus 531: /*
532: * Open a connection to the remote host. This needs root privileges
533: * if rhosts_{rsa_}authentication is enabled.
534: */
1.31 markus 535:
536: ok = ssh_connect(host, &hostaddr, options.port,
537: options.connection_attempts,
538: !options.rhosts_authentication &&
539: !options.rhosts_rsa_authentication,
540: original_real_uid,
541: options.proxy_command);
542:
1.33 markus 543: /*
544: * If we successfully made the connection, load the host private key
545: * in case we will need it later for combined rsa-rhosts
546: * authentication. This must be done before releasing extra
547: * privileges, because the file is only readable by root.
548: */
1.31 markus 549: if (ok) {
550: host_private_key = RSA_new();
551: if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL))
552: host_private_key_loaded = 1;
553: }
1.33 markus 554: /*
555: * Get rid of any extra privileges that we may have. We will no
556: * longer need them. Also, extra privileges could make it very hard
557: * to read identity files and other non-world-readable files from the
558: * user's home directory if it happens to be on a NFS volume where
559: * root is mapped to nobody.
560: */
561:
562: /*
563: * Note that some legacy systems need to postpone the following call
564: * to permanently_set_uid() until the private hostkey is destroyed
565: * with RSA_free(). Otherwise the calling user could ptrace() the
566: * process, read the private hostkey and impersonate the host.
567: * OpenBSD does not allow ptracing of setuid processes.
568: */
1.31 markus 569: permanently_set_uid(original_real_uid);
570:
1.33 markus 571: /*
572: * Now that we are back to our own permissions, create ~/.ssh
573: * directory if it doesn\'t already exist.
574: */
1.31 markus 575: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR);
576: if (stat(buf, &st) < 0)
577: if (mkdir(buf, 0755) < 0)
578: error("Could not create directory '%.200s'.", buf);
579:
580: /* Check if the connection failed, and try "rsh" if appropriate. */
581: if (!ok) {
582: if (options.port != 0)
1.35 markus 583: log("Secure connection to %.100s on port %hu refused%.100s.",
1.31 markus 584: host, options.port,
585: options.fallback_to_rsh ? "; reverting to insecure method" : "");
586: else
587: log("Secure connection to %.100s refused%.100s.", host,
588: options.fallback_to_rsh ? "; reverting to insecure method" : "");
589:
590: if (options.fallback_to_rsh) {
591: rsh_connect(host, options.user, &command);
592: fatal("rsh_connect returned");
593: }
594: exit(1);
595: }
596: /* Expand ~ in options.identity_files. */
597: for (i = 0; i < options.num_identity_files; i++)
598: options.identity_files[i] =
599: tilde_expand_filename(options.identity_files[i], original_real_uid);
600:
601: /* Expand ~ in known host file names. */
602: options.system_hostfile = tilde_expand_filename(options.system_hostfile,
603: original_real_uid);
604: options.user_hostfile = tilde_expand_filename(options.user_hostfile,
605: original_real_uid);
606:
607: /* Log into the remote system. This never returns if the login fails. */
608: ssh_login(host_private_key_loaded, host_private_key,
1.37 markus 609: host, (struct sockaddr *)&hostaddr, original_real_uid);
1.31 markus 610:
611: /* We no longer need the host private key. Clear it now. */
612: if (host_private_key_loaded)
613: RSA_free(host_private_key); /* Destroys contents safely */
614:
615: /* Enable compression if requested. */
616: if (options.compression) {
617: debug("Requesting compression at level %d.", options.compression_level);
618:
619: if (options.compression_level < 1 || options.compression_level > 9)
620: fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
621:
622: /* Send the request. */
623: packet_start(SSH_CMSG_REQUEST_COMPRESSION);
624: packet_put_int(options.compression_level);
625: packet_send();
626: packet_write_wait();
627: type = packet_read(&plen);
628: if (type == SSH_SMSG_SUCCESS)
629: packet_start_compression(options.compression_level);
630: else if (type == SSH_SMSG_FAILURE)
631: log("Warning: Remote host refused compression.");
632: else
633: packet_disconnect("Protocol error waiting for compression response.");
634: }
635: /* Allocate a pseudo tty if appropriate. */
636: if (tty_flag) {
637: debug("Requesting pty.");
638:
639: /* Start the packet. */
640: packet_start(SSH_CMSG_REQUEST_PTY);
641:
642: /* Store TERM in the packet. There is no limit on the
643: length of the string. */
644: cp = getenv("TERM");
645: if (!cp)
646: cp = "";
647: packet_put_string(cp, strlen(cp));
648:
649: /* Store window size in the packet. */
650: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
651: memset(&ws, 0, sizeof(ws));
652: packet_put_int(ws.ws_row);
653: packet_put_int(ws.ws_col);
654: packet_put_int(ws.ws_xpixel);
655: packet_put_int(ws.ws_ypixel);
656:
657: /* Store tty modes in the packet. */
658: tty_make_modes(fileno(stdin));
659:
660: /* Send the packet, and wait for it to leave. */
661: packet_send();
662: packet_write_wait();
663:
664: /* Read response from the server. */
665: type = packet_read(&plen);
1.43 markus 666: if (type == SSH_SMSG_SUCCESS) {
1.31 markus 667: interactive = 1;
1.43 markus 668: have_pty = 1;
669: } else if (type == SSH_SMSG_FAILURE)
1.31 markus 670: log("Warning: Remote host failed or refused to allocate a pseudo tty.");
671: else
672: packet_disconnect("Protocol error waiting for pty request response.");
673: }
674: /* Request X11 forwarding if enabled and DISPLAY is set. */
675: if (options.forward_x11 && getenv("DISPLAY") != NULL) {
676: char line[512], proto[512], data[512];
677: FILE *f;
678: int forwarded = 0, got_data = 0, i;
1.1 deraadt 679:
680: #ifdef XAUTH_PATH
1.31 markus 681: /* Try to get Xauthority information for the display. */
682: snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null",
683: XAUTH_PATH, getenv("DISPLAY"));
684: f = popen(line, "r");
685: if (f && fgets(line, sizeof(line), f) &&
686: sscanf(line, "%*s %s %s", proto, data) == 2)
687: got_data = 1;
688: if (f)
689: pclose(f);
1.1 deraadt 690: #endif /* XAUTH_PATH */
1.33 markus 691: /*
692: * If we didn't get authentication data, just make up some
693: * data. The forwarding code will check the validity of the
694: * response anyway, and substitute this data. The X11
695: * server, however, will ignore this fake data and use
696: * whatever authentication mechanisms it was using otherwise
697: * for the local connection.
698: */
1.31 markus 699: if (!got_data) {
700: u_int32_t rand = 0;
701:
702: strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
703: for (i = 0; i < 16; i++) {
704: if (i % 4 == 0)
705: rand = arc4random();
706: snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
707: rand >>= 8;
708: }
709: }
1.33 markus 710: /*
711: * Got local authentication reasonable information. Request
712: * forwarding with authentication spoofing.
713: */
1.31 markus 714: debug("Requesting X11 forwarding with authentication spoofing.");
715: x11_request_forwarding_with_spoofing(proto, data);
716:
717: /* Read response from the server. */
718: type = packet_read(&plen);
719: if (type == SSH_SMSG_SUCCESS) {
720: forwarded = 1;
721: interactive = 1;
722: } else if (type == SSH_SMSG_FAILURE)
723: log("Warning: Remote host denied X11 forwarding.");
724: else
725: packet_disconnect("Protocol error waiting for X11 forwarding");
726: }
727: /* Tell the packet module whether this is an interactive session. */
728: packet_set_interactive(interactive, options.keepalives);
729:
730: /* Clear agent forwarding if we don\'t have an agent. */
731: authfd = ssh_get_authentication_socket();
732: if (authfd < 0)
733: options.forward_agent = 0;
734: else
735: ssh_close_authentication_socket(authfd);
736:
737: /* Request authentication agent forwarding if appropriate. */
738: if (options.forward_agent) {
739: debug("Requesting authentication agent forwarding.");
740: auth_request_forwarding();
741:
742: /* Read response from the server. */
743: type = packet_read(&plen);
744: packet_integrity_check(plen, 0, type);
745: if (type != SSH_SMSG_SUCCESS)
746: log("Warning: Remote host denied authentication agent forwarding.");
747: }
748: /* Initiate local TCP/IP port forwardings. */
749: for (i = 0; i < options.num_local_forwards; i++) {
750: debug("Connections to local port %d forwarded to remote address %.200s:%d",
751: options.local_forwards[i].port,
752: options.local_forwards[i].host,
753: options.local_forwards[i].host_port);
754: channel_request_local_forwarding(options.local_forwards[i].port,
755: options.local_forwards[i].host,
1.36 markus 756: options.local_forwards[i].host_port,
757: options.gateway_ports);
1.31 markus 758: }
759:
760: /* Initiate remote TCP/IP port forwardings. */
761: for (i = 0; i < options.num_remote_forwards; i++) {
762: debug("Connections to remote port %d forwarded to local address %.200s:%d",
763: options.remote_forwards[i].port,
764: options.remote_forwards[i].host,
765: options.remote_forwards[i].host_port);
766: channel_request_remote_forwarding(options.remote_forwards[i].port,
767: options.remote_forwards[i].host,
768: options.remote_forwards[i].host_port);
769: }
1.34 markus 770:
771: /* If requested, let ssh continue in the background. */
772: if (fork_after_authentication_flag)
773: if (daemon(1, 1) < 0)
774: fatal("daemon() failed: %.200s", strerror(errno));
1.31 markus 775:
1.33 markus 776: /*
777: * If a command was specified on the command line, execute the
778: * command now. Otherwise request the server to start a shell.
779: */
1.31 markus 780: if (buffer_len(&command) > 0) {
781: int len = buffer_len(&command);
782: if (len > 900)
783: len = 900;
784: debug("Sending command: %.*s", len, buffer_ptr(&command));
785: packet_start(SSH_CMSG_EXEC_CMD);
786: packet_put_string(buffer_ptr(&command), buffer_len(&command));
787: packet_send();
788: packet_write_wait();
789: } else {
790: debug("Requesting shell.");
791: packet_start(SSH_CMSG_EXEC_SHELL);
792: packet_send();
793: packet_write_wait();
794: }
795:
796: /* Enter the interactive session. */
1.43 markus 797: exit_status = client_loop(have_pty, tty_flag ? options.escape_char : -1);
1.31 markus 798:
799: /* Close the connection to the remote host. */
800: packet_close();
801:
802: /* Exit with the status returned by the program on the remote side. */
803: exit(exit_status);
1.1 deraadt 804: }
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