Annotation of src/usr.bin/ssh/ssh.c, Revision 1.23
1.1 deraadt 1: /*
2:
3: ssh.c
4:
5: Author: Tatu Ylonen <ylo@cs.hut.fi>
6:
7: Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8: All rights reserved
9:
10: Created: Sat Mar 18 16:36:11 1995 ylo
11:
12: Ssh client program. This program can be used to log into a remote machine.
13: The software supports strong authentication, encryption, and forwarding
14: of X11, TCP/IP, and authentication connections.
15:
1.2 provos 16: Modified to work with SSL by Niels Provos <provos@citi.umich.edu> in Canada.
17:
1.1 deraadt 18: */
19:
20: #include "includes.h"
1.23 ! markus 21: RCSID("$Id: ssh.c,v 1.22 1999/10/03 21:50:04 provos Exp $");
1.1 deraadt 22:
23: #include "xmalloc.h"
24: #include "ssh.h"
25: #include "packet.h"
26: #include "buffer.h"
27: #include "authfd.h"
28: #include "readconf.h"
29: #include "uidswap.h"
30:
31: /* Flag indicating whether debug mode is on. This can be set on the
32: command line. */
33: int debug_flag = 0;
34:
35: /* Flag indicating whether quiet mode is on. */
36: int quiet_flag = 0;
37:
38: /* Flag indicating whether to allocate a pseudo tty. This can be set on the
39: command line, and is automatically set if no command is given on the command
40: line. */
41: int tty_flag = 0;
42:
43: /* Flag indicating that nothing should be read from stdin. This can be set
44: on the command line. */
45: int stdin_null_flag = 0;
46:
47: /* Flag indicating that ssh should fork after authentication. This is useful
48: so that the pasphrase can be entered manually, and then ssh goes to the
49: background. */
50: int fork_after_authentication_flag = 0;
51:
52: /* General data structure for command line options and options configurable
53: in configuration files. See readconf.h. */
54: Options options;
55:
56: /* Name of the host we are connecting to. This is the name given on the
57: command line, or the HostName specified for the user-supplied name
58: in a configuration file. */
59: char *host;
60:
1.22 provos 61: /* socket address the host resolves to */
62: struct sockaddr_in hostaddr;
63:
1.1 deraadt 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: 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: {
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");
1.7 provos 91: fprintf(stderr, " -a Disable authentication agent forwarding.\n");
1.9 dugsong 92: #ifdef AFS
93: fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n");
94: #endif /* AFS */
1.1 deraadt 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");
1.8 provos 99: fprintf(stderr, " -V Display version number only.\n");
1.23 ! markus 100: fprintf(stderr, " -P Don't allocate a privileged port.\n");
1.1 deraadt 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:
1.19 provos 105: fprintf(stderr, " -c cipher Select encryption algorithm: "
106: "``3des'', "
107: "``blowfish''\n");
1.1 deraadt 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");
1.21 deraadt 114: fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n");
1.1 deraadt 115: fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n");
116: exit(1);
117: }
118:
119: /* Connects to the given host using rsh (or prints an error message and exits
120: if rsh is not available). This function never returns. */
121:
1.2 provos 122: void
123: rsh_connect(char *host, char *user, Buffer *command)
1.1 deraadt 124: {
125: char *args[10];
126: int i;
127:
128: log("Using rsh. WARNING: Connection will not be encrypted.");
129: /* Build argument list for rsh. */
130: i = 0;
1.13 deraadt 131: args[i++] = _PATH_RSH;
1.1 deraadt 132: args[i++] = host; /* may have to come after user on some systems */
133: if (user)
134: {
135: args[i++] = "-l";
136: args[i++] = user;
137: }
138: if (buffer_len(command) > 0)
139: {
140: buffer_append(command, "\0", 1);
141: args[i++] = buffer_ptr(command);
142: }
143: args[i++] = NULL;
144: if (debug_flag)
145: {
146: for (i = 0; args[i]; i++)
147: {
148: if (i != 0)
149: fprintf(stderr, " ");
150: fprintf(stderr, "%s", args[i]);
151: }
152: fprintf(stderr, "\n");
153: }
1.13 deraadt 154: execv(_PATH_RSH, args);
155: perror(_PATH_RSH);
1.1 deraadt 156: exit(1);
157: }
158:
159: /* Main program for the ssh client. */
160:
1.11 deraadt 161: uid_t original_real_uid;
162:
1.2 provos 163: int
164: main(int ac, char **av)
1.1 deraadt 165: {
166: int i, opt, optind, type, exit_status, ok, fwd_port, fwd_host_port, authfd;
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:
176: /* Save the original real uid. It will be needed later (uid-swapping may
177: clobber the real uid). */
178: original_real_uid = getuid();
179: original_effective_uid = geteuid();
180:
181: /* If we are installed setuid root be careful to not drop core. */
182: if (original_real_uid != original_effective_uid)
183: {
184: struct rlimit rlim;
185: rlim.rlim_cur = rlim.rlim_max = 0;
186: if (setrlimit(RLIMIT_CORE, &rlim) < 0)
187: fatal("setrlimit failed: %.100s", strerror(errno));
188: }
189:
190: /* Use uid-swapping to give up root privileges for the duration of option
191: processing. We will re-instantiate the rights when we are ready to
192: create the privileged port, and will permanently drop them when the
193: port has been created (actually, when the connection has been made, as
194: we may need to create the port several times). */
195: temporarily_use_uid(original_real_uid);
196:
197: /* Set our umask to something reasonable, as some files are created with
198: the default umask. This will make them world-readable but writable
199: only by the owner, which is ok for all files for which we don't set
200: the modes explicitly. */
201: umask(022);
202:
203: /* Save our own name. */
204: av0 = av[0];
205:
206: /* Initialize option structure to indicate that no values have been set. */
207: initialize_options(&options);
208:
209: /* Parse command-line arguments. */
210: host = NULL;
211:
212: /* If program name is not one of the standard names, use it as host name. */
213: if (strchr(av0, '/'))
214: cp = strrchr(av0, '/') + 1;
215: else
216: cp = av0;
217: if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 &&
218: strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0)
219: host = cp;
220:
221: for (optind = 1; optind < ac; optind++)
222: {
223: if (av[optind][0] != '-')
224: {
225: if (host)
226: break;
1.3 deraadt 227: if ((cp = strchr(av[optind], '@'))) {
228: options.user = av[optind];
229: *cp = '\0';
230: host = ++cp;
231: }
232: else
233: host = av[optind];
1.1 deraadt 234: continue;
235: }
236: opt = av[optind][1];
237: if (!opt)
238: usage();
239: if (strchr("eilcpLRo", opt)) /* options with arguments */
240: {
241: optarg = av[optind] + 2;
242: if (strcmp(optarg, "") == 0)
243: {
244: if (optind >= ac - 1)
245: usage();
246: optarg = av[++optind];
247: }
248: }
249: else
250: {
251: if (av[optind][2])
252: usage();
253: optarg = NULL;
254: }
255: switch (opt)
256: {
257: case 'n':
258: stdin_null_flag = 1;
259: break;
260:
261: case 'f':
262: fork_after_authentication_flag = 1;
263: stdin_null_flag = 1;
264: break;
265:
266: case 'x':
267: options.forward_x11 = 0;
268: break;
269:
270: case 'X':
271: options.forward_x11 = 1;
1.4 deraadt 272: break;
273:
274: case 'g':
275: options.gateway_ports = 1;
1.1 deraadt 276: break;
277:
1.23 ! markus 278: case 'P':
! 279: options.use_privileged_port = 0;
! 280: break;
! 281:
1.1 deraadt 282: case 'a':
283: options.forward_agent = 0;
1.9 dugsong 284: break;
285: #ifdef AFS
286: case 'k':
1.1 deraadt 287: options.kerberos_tgt_passing = 0;
288: options.afs_token_passing = 0;
1.9 dugsong 289: break;
1.1 deraadt 290: #endif
291: case 'i':
292: if (stat(optarg, &st) < 0)
293: {
294: fprintf(stderr, "Warning: Identity file %s does not exist.\n",
295: optarg);
296: break;
297: }
298: if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES)
299: fatal("Too many identity files specified (max %d)",
300: SSH_MAX_IDENTITY_FILES);
301: options.identity_files[options.num_identity_files++] =
302: xstrdup(optarg);
303: break;
304:
305: case 't':
306: tty_flag = 1;
307: break;
308:
309: case 'v':
1.6 deraadt 310: case 'V':
1.1 deraadt 311: debug_flag = 1;
312: fprintf(stderr, "SSH Version %s, protocol version %d.%d.\n",
313: SSH_VERSION, PROTOCOL_MAJOR, PROTOCOL_MINOR);
314: fprintf(stderr, "Compiled with SSL.\n");
1.6 deraadt 315: if (opt == 'V')
316: exit(0);
1.1 deraadt 317: break;
318:
319: case 'q':
320: quiet_flag = 1;
321: break;
322:
323: case 'e':
324: if (optarg[0] == '^' && optarg[2] == 0 &&
325: (unsigned char)optarg[1] >= 64 && (unsigned char)optarg[1] < 128)
326: options.escape_char = (unsigned char)optarg[1] & 31;
327: else
328: if (strlen(optarg) == 1)
329: options.escape_char = (unsigned char)optarg[0];
330: else
331: if (strcmp(optarg, "none") == 0)
332: options.escape_char = -2;
333: else
334: {
335: fprintf(stderr, "Bad escape character '%s'.\n", optarg);
336: exit(1);
337: }
338: break;
339:
340: case 'c':
341: options.cipher = cipher_number(optarg);
342: if (options.cipher == -1)
343: {
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: if (options.port < 1 || options.port > 65535)
352: {
353: fprintf(stderr, "Bad port %s.\n", optarg);
354: exit(1);
355: }
356: break;
357:
358: case 'l':
359: options.user = optarg;
360: break;
361:
362: case 'R':
363: if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf,
364: &fwd_host_port) != 3)
365: {
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':
374: if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf,
375: &fwd_host_port) != 3)
376: {
377: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
378: usage();
379: /*NOTREACHED*/
380: }
381: add_local_forward(&options, fwd_port, buf, fwd_host_port);
382: break;
383:
384: case 'C':
385: options.compression = 1;
386: break;
387:
388: case 'o':
389: dummy = 1;
390: process_config_line(&options, host ? host : "", optarg,
391: "command-line", 0, &dummy);
392: break;
393:
394: default:
395: usage();
396: }
397: }
398:
399: /* Check that we got a host name. */
400: if (!host)
401: usage();
1.5 deraadt 402:
403: /* check if RSA support exists */
404: if (rsa_alive() == 0) {
405: extern char *__progname;
406:
407: fprintf(stderr,
408: "%s: no RSA support in libssl and libcrypto. See ssl(8).\n",
409: __progname);
410: exit(1);
411: }
1.1 deraadt 412:
413: /* Initialize the command to execute on remote host. */
414: buffer_init(&command);
415:
416: /* Save the command to execute on the remote host in a buffer. There is
417: no limit on the length of the command, except by the maximum packet
418: size. Also sets the tty flag if there is no command. */
419: if (optind == ac)
420: {
421: /* No command specified - execute shell on a tty. */
422: tty_flag = 1;
423: }
424: else
425: {
426: /* A command has been specified. Store it into the buffer. */
427: for (i = optind; i < ac; i++)
428: {
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: {
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:
451: /* Get user data. */
452: pw = getpwuid(original_real_uid);
453: if (!pw)
454: {
455: fprintf(stderr, "You don't exist, go away!\n");
456: exit(1);
457: }
458:
459: /* Take a copy of the returned structure. */
460: memset(&pwcopy, 0, sizeof(pwcopy));
461: pwcopy.pw_name = xstrdup(pw->pw_name);
462: pwcopy.pw_passwd = xstrdup(pw->pw_passwd);
463: pwcopy.pw_uid = pw->pw_uid;
464: pwcopy.pw_gid = pw->pw_gid;
465: pwcopy.pw_dir = xstrdup(pw->pw_dir);
466: pwcopy.pw_shell = xstrdup(pw->pw_shell);
467: pw = &pwcopy;
468:
469: /* Initialize "log" output. Since we are the client all output actually
470: goes to the terminal. */
471: log_init(av[0], 1, debug_flag, quiet_flag, SYSLOG_FACILITY_USER);
472:
473: /* Read per-user configuration file. */
1.11 deraadt 474: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE);
1.1 deraadt 475: read_config_file(buf, host, &options);
476:
477: /* Read systemwide configuration file. */
478: read_config_file(HOST_CONFIG_FILE, host, &options);
479:
480: /* Fill configuration defaults. */
481: fill_default_options(&options);
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)
490: {
491: struct hostent *hp = gethostbyname(host);
492: if (hp != 0)
493: {
494: if (strchr(hp->h_name, '.') != 0)
495: host = xstrdup(hp->h_name);
496: else if (hp->h_aliases != 0
497: && hp->h_aliases[0] != 0
498: && strchr(hp->h_aliases[0], '.') != 0)
499: host = xstrdup(hp->h_aliases[0]);
500: }
501: }
502:
503: /* Disable rhosts authentication if not running as root. */
504: if (original_effective_uid != 0)
505: {
506: options.rhosts_authentication = 0;
507: options.rhosts_rsa_authentication = 0;
508: }
509:
510: /* If using rsh has been selected, exec it now (without trying anything
511: else). Note that we must release privileges first. */
512: if (options.use_rsh)
513: {
514: /* Restore our superuser privileges. This must be done before
515: permanently setting the uid. */
516: restore_uid();
517:
518: /* Switch to the original uid permanently. */
519: permanently_set_uid(original_real_uid);
520:
521: /* Execute rsh. */
522: rsh_connect(host, options.user, &command);
523: fatal("rsh_connect returned");
524: }
525:
526: /* Restore our superuser privileges. */
527: restore_uid();
528:
529: /* Open a connection to the remote host. This needs root privileges if
1.23 ! markus 530: rhosts_{rsa_}authentication is true. */
! 531:
! 532: if (!options.use_privileged_port)
! 533: {
! 534: options.rhosts_authentication = 0;
! 535: options.rhosts_rsa_authentication = 0;
! 536: }
! 537:
1.22 provos 538: ok = ssh_connect(host, &hostaddr, options.port, options.connection_attempts,
1.1 deraadt 539: !options.rhosts_authentication &&
540: !options.rhosts_rsa_authentication,
1.2 provos 541: original_real_uid, options.proxy_command);
1.1 deraadt 542:
543: /* If we successfully made the connection, load the host private key in
544: case we will need it later for combined rsa-rhosts authentication.
545: This must be done before releasing extra privileges, because the file
546: is only readable by root. */
547: if (ok)
548: {
1.2 provos 549: host_private_key = RSA_new();
550: if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL))
1.1 deraadt 551: host_private_key_loaded = 1;
552: }
553:
554: /* Get rid of any extra privileges that we may have. We will no longer need
555: them. Also, extra privileges could make it very hard to read identity
556: files and other non-world-readable files from the user's home directory
557: if it happens to be on a NFS volume where root is mapped to nobody. */
558: permanently_set_uid(original_real_uid);
559:
560: /* Now that we are back to our own permissions, create ~/.ssh directory
561: if it doesn\'t already exist. */
1.11 deraadt 562: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR);
1.1 deraadt 563: if (stat(buf, &st) < 0)
564: if (mkdir(buf, 0755) < 0)
565: error("Could not create directory '%.200s'.", buf);
566:
567: /* Check if the connection failed, and try "rsh" if appropriate. */
568: if (!ok)
569: {
570: if (options.port != 0)
571: log("Secure connection to %.100s on port %d refused%.100s.",
572: host, options.port,
573: options.fallback_to_rsh ? "; reverting to insecure method" : "");
574: else
575: log("Secure connection to %.100s refused%.100s.", host,
576: options.fallback_to_rsh ? "; reverting to insecure method" : "");
577:
578: if (options.fallback_to_rsh)
579: {
580: rsh_connect(host, options.user, &command);
581: fatal("rsh_connect returned");
582: }
583: exit(1);
584: }
585:
586: /* Expand ~ in options.identity_files. */
587: for (i = 0; i < options.num_identity_files; i++)
588: options.identity_files[i] =
589: tilde_expand_filename(options.identity_files[i], original_real_uid);
590:
591: /* Expand ~ in known host file names. */
592: options.system_hostfile = tilde_expand_filename(options.system_hostfile,
593: original_real_uid);
594: options.user_hostfile = tilde_expand_filename(options.user_hostfile,
595: original_real_uid);
596:
1.2 provos 597: /* Log into the remote system. This never returns if the login fails. */
598: ssh_login(host_private_key_loaded, host_private_key,
1.22 provos 599: host, &hostaddr, &options, original_real_uid);
1.1 deraadt 600:
601: /* We no longer need the host private key. Clear it now. */
602: if (host_private_key_loaded)
1.2 provos 603: RSA_free(host_private_key); /* Destroys contents safely */
1.1 deraadt 604:
605: /* Close connection cleanly after attack. */
606: cipher_attack_detected = packet_disconnect;
607:
608: /* If requested, fork and let ssh continue in the background. */
609: if (fork_after_authentication_flag)
610: {
611: int ret = fork();
612: if (ret == -1)
613: fatal("fork failed: %.100s", strerror(errno));
614: if (ret != 0)
615: exit(0);
616: setsid();
617: }
618:
619: /* Enable compression if requested. */
620: if (options.compression)
621: {
622: debug("Requesting compression at level %d.", options.compression_level);
623:
624: if (options.compression_level < 1 || options.compression_level > 9)
625: fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
626:
627: /* Send the request. */
628: packet_start(SSH_CMSG_REQUEST_COMPRESSION);
629: packet_put_int(options.compression_level);
630: packet_send();
631: packet_write_wait();
632: type = packet_read(&plen);
633: if (type == SSH_SMSG_SUCCESS)
634: packet_start_compression(options.compression_level);
635: else if (type == SSH_SMSG_FAILURE)
636: log("Warning: Remote host refused compression.");
637: else
638: packet_disconnect("Protocol error waiting for compression response.");
639: }
640:
641: /* Allocate a pseudo tty if appropriate. */
642: if (tty_flag)
643: {
644: debug("Requesting pty.");
645:
646: /* Start the packet. */
647: packet_start(SSH_CMSG_REQUEST_PTY);
648:
649: /* Store TERM in the packet. There is no limit on the length of the
650: string. */
651: cp = getenv("TERM");
652: if (!cp)
653: cp = "";
654: packet_put_string(cp, strlen(cp));
655:
656: /* Store window size in the packet. */
657: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
658: memset(&ws, 0, sizeof(ws));
659: packet_put_int(ws.ws_row);
660: packet_put_int(ws.ws_col);
661: packet_put_int(ws.ws_xpixel);
662: packet_put_int(ws.ws_ypixel);
663:
664: /* Store tty modes in the packet. */
665: tty_make_modes(fileno(stdin));
666:
667: /* Send the packet, and wait for it to leave. */
668: packet_send();
669: packet_write_wait();
670:
671: /* Read response from the server. */
672: type = packet_read(&plen);
673: if (type == SSH_SMSG_SUCCESS)
674: interactive = 1;
675: else if (type == SSH_SMSG_FAILURE)
676: log("Warning: Remote host failed or refused to allocate a pseudo tty.");
677: else
678: packet_disconnect("Protocol error waiting for pty request response.");
679: }
680:
681: /* Request X11 forwarding if enabled and DISPLAY is set. */
682: if (options.forward_x11 && getenv("DISPLAY") != NULL)
683: {
684: char line[512], proto[512], data[512];
685: FILE *f;
686: int forwarded = 0, got_data = 0, i;
687:
688: #ifdef XAUTH_PATH
689: /* Try to get Xauthority information for the display. */
1.11 deraadt 690: snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null",
1.1 deraadt 691: XAUTH_PATH, getenv("DISPLAY"));
692: f = popen(line, "r");
693: if (f && fgets(line, sizeof(line), f) &&
694: sscanf(line, "%*s %s %s", proto, data) == 2)
695: got_data = 1;
696: if (f)
697: pclose(f);
698: #endif /* XAUTH_PATH */
699: /* If we didn't get authentication data, just make up some data. The
700: forwarding code will check the validity of the response anyway, and
701: substitute this data. The X11 server, however, will ignore this
702: fake data and use whatever authentication mechanisms it was using
703: otherwise for the local connection. */
704: if (!got_data)
705: {
1.9 dugsong 706: u_int32_t rand = 0;
1.2 provos 707:
1.11 deraadt 708: strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
1.2 provos 709: for (i = 0; i < 16; i++) {
710: if (i % 4 == 0)
711: rand = arc4random();
1.11 deraadt 712: snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
1.2 provos 713: rand >>= 8;
714: }
1.1 deraadt 715: }
716:
717: /* Got local authentication reasonable information. Request forwarding
718: with authentication spoofing. */
719: debug("Requesting X11 forwarding with authentication spoofing.");
1.2 provos 720: x11_request_forwarding_with_spoofing(proto, data);
1.1 deraadt 721:
722: /* Read response from the server. */
723: type = packet_read(&plen);
724: if (type == SSH_SMSG_SUCCESS)
725: {
726: forwarded = 1;
727: interactive = 1;
728: }
729: else if (type == SSH_SMSG_FAILURE)
730: log("Warning: Remote host denied X11 forwarding.");
731: else
732: packet_disconnect("Protocol error waiting for X11 forwarding");
733: }
734:
735: /* Tell the packet module whether this is an interactive session. */
736: packet_set_interactive(interactive, options.keepalives);
737:
738: /* Clear agent forwarding if we don\'t have an agent. */
739: authfd = ssh_get_authentication_fd();
740: if (authfd < 0)
741: options.forward_agent = 0;
742: else
743: ssh_close_authentication_socket(authfd);
744:
745: /* Request authentication agent forwarding if appropriate. */
746: if (options.forward_agent)
747: {
748: debug("Requesting authentication agent forwarding.");
749: auth_request_forwarding();
750:
751: /* Read response from the server. */
752: type = packet_read(&plen);
753: packet_integrity_check(plen, 0, type);
754: if (type != SSH_SMSG_SUCCESS)
755: log("Warning: Remote host denied authentication agent forwarding.");
756: }
757:
758: /* Initiate local TCP/IP port forwardings. */
759: for (i = 0; i < options.num_local_forwards; i++)
760: {
761: debug("Connections to local port %d forwarded to remote address %.200s:%d",
762: options.local_forwards[i].port, options.local_forwards[i].host,
763: options.local_forwards[i].host_port);
764: channel_request_local_forwarding(options.local_forwards[i].port,
765: options.local_forwards[i].host,
766: options.local_forwards[i].host_port);
767: }
768:
769: /* Initiate remote TCP/IP port forwardings. */
770: for (i = 0; i < options.num_remote_forwards; i++)
771: {
772: debug("Connections to remote port %d forwarded to local address %.200s:%d",
773: options.remote_forwards[i].port, options.remote_forwards[i].host,
774: options.remote_forwards[i].host_port);
775: channel_request_remote_forwarding(options.remote_forwards[i].port,
776: options.remote_forwards[i].host,
777: options.remote_forwards[i].host_port);
778: }
779:
780: /* If a command was specified on the command line, execute the command now.
781: Otherwise request the server to start a shell. */
782: if (buffer_len(&command) > 0)
783: {
784: int len = buffer_len(&command);
785: if (len > 900)
786: len = 900;
787: debug("Sending command: %.*s", len, buffer_ptr(&command));
788: packet_start(SSH_CMSG_EXEC_CMD);
789: packet_put_string(buffer_ptr(&command), buffer_len(&command));
790: packet_send();
791: packet_write_wait();
792: }
793: else
794: {
795: debug("Requesting shell.");
796: packet_start(SSH_CMSG_EXEC_SHELL);
797: packet_send();
798: packet_write_wait();
799: }
800:
801: /* Enter the interactive session. */
802: exit_status = client_loop(tty_flag, tty_flag ? options.escape_char : -1);
803:
804: /* Close the connection to the remote host. */
805: packet_close();
806:
807: /* Exit with the status returned by the program on the remote side. */
808: exit(exit_status);
809: }