Annotation of src/usr.bin/ssh/ssh.c, Revision 1.28
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"
1.28 ! markus 21: RCSID("$Id: ssh.c,v 1.27 1999/11/10 23:36:44 markus 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 to allocate a pseudo tty. This can be set on the
36: command line, and is automatically set if no command is given on the command
37: line. */
38: int tty_flag = 0;
39:
40: /* Flag indicating that nothing should be read from stdin. This can be set
41: on the command line. */
42: int stdin_null_flag = 0;
43:
44: /* Flag indicating that ssh should fork after authentication. This is useful
45: so that the pasphrase can be entered manually, and then ssh goes to the
46: background. */
47: int fork_after_authentication_flag = 0;
48:
49: /* General data structure for command line options and options configurable
50: in configuration files. See readconf.h. */
51: Options options;
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
55: in a configuration file. */
56: char *host;
57:
1.22 provos 58: /* socket address the host resolves to */
59: struct sockaddr_in hostaddr;
60:
1.1 deraadt 61: /* Flag to indicate that we have received a window change signal which has
62: not yet been processed. This will cause a message indicating the new
63: window size to be sent to the server a little later. This is volatile
64: because this is updated in a signal handler. */
65: volatile int received_window_change_signal = 0;
66:
67: /* Value of argv[0] (set in the main program). */
68: char *av0;
69:
70: /* Flag indicating whether we have a valid host private key loaded. */
71: int host_private_key_loaded = 0;
72:
73: /* Host private key. */
1.2 provos 74: RSA *host_private_key = NULL;
1.1 deraadt 75:
1.10 dugsong 76: /* Original real UID. */
77: uid_t original_real_uid;
1.1 deraadt 78:
79: /* Prints a help message to the user. This function never returns. */
80:
1.2 provos 81: void
82: usage()
1.1 deraadt 83: {
84: fprintf(stderr, "Usage: %s [options] host [command]\n", av0);
85: fprintf(stderr, "Options:\n");
86: fprintf(stderr, " -l user Log in using this user name.\n");
87: fprintf(stderr, " -n Redirect input from /dev/null.\n");
1.7 provos 88: fprintf(stderr, " -a Disable authentication agent forwarding.\n");
1.9 dugsong 89: #ifdef AFS
90: fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n");
91: #endif /* AFS */
1.1 deraadt 92: fprintf(stderr, " -x Disable X11 connection forwarding.\n");
93: fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n");
94: fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n");
95: fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
1.8 provos 96: fprintf(stderr, " -V Display version number only.\n");
1.23 markus 97: fprintf(stderr, " -P Don't allocate a privileged port.\n");
1.1 deraadt 98: fprintf(stderr, " -q Quiet; don't display any warning messages.\n");
99: fprintf(stderr, " -f Fork into background after authentication.\n");
100: fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n");
101:
1.19 provos 102: fprintf(stderr, " -c cipher Select encryption algorithm: "
103: "``3des'', "
104: "``blowfish''\n");
1.1 deraadt 105: fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n");
106: fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n");
107: fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n");
108: fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0);
109: fprintf(stderr, " forward them to the other side by connecting to host:port.\n");
110: fprintf(stderr, " -C Enable compression.\n");
1.21 deraadt 111: fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n");
1.1 deraadt 112: fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n");
113: exit(1);
114: }
115:
116: /* Connects to the given host using rsh (or prints an error message and exits
117: if rsh is not available). This function never returns. */
118:
1.2 provos 119: void
120: rsh_connect(char *host, char *user, Buffer *command)
1.1 deraadt 121: {
122: char *args[10];
123: int i;
124:
125: log("Using rsh. WARNING: Connection will not be encrypted.");
126: /* Build argument list for rsh. */
127: i = 0;
1.13 deraadt 128: args[i++] = _PATH_RSH;
1.1 deraadt 129: args[i++] = host; /* may have to come after user on some systems */
130: if (user)
131: {
132: args[i++] = "-l";
133: args[i++] = user;
134: }
135: if (buffer_len(command) > 0)
136: {
137: buffer_append(command, "\0", 1);
138: args[i++] = buffer_ptr(command);
139: }
140: args[i++] = NULL;
141: if (debug_flag)
142: {
143: for (i = 0; args[i]; i++)
144: {
145: if (i != 0)
146: fprintf(stderr, " ");
147: fprintf(stderr, "%s", args[i]);
148: }
149: fprintf(stderr, "\n");
150: }
1.13 deraadt 151: execv(_PATH_RSH, args);
152: perror(_PATH_RSH);
1.1 deraadt 153: exit(1);
154: }
155:
156: /* Main program for the ssh client. */
1.11 deraadt 157:
1.2 provos 158: int
159: main(int ac, char **av)
1.1 deraadt 160: {
161: int i, opt, optind, type, exit_status, ok, fwd_port, fwd_host_port, authfd;
162: char *optarg, *cp, buf[256];
163: Buffer command;
164: struct winsize ws;
165: struct stat st;
166: struct passwd *pw, pwcopy;
167: int interactive = 0, dummy;
168: uid_t original_effective_uid;
169: int plen;
170:
171: /* Save the original real uid. It will be needed later (uid-swapping may
172: clobber the real uid). */
173: original_real_uid = getuid();
174: original_effective_uid = geteuid();
175:
176: /* If we are installed setuid root be careful to not drop core. */
177: if (original_real_uid != original_effective_uid)
178: {
179: struct rlimit rlim;
180: rlim.rlim_cur = rlim.rlim_max = 0;
181: if (setrlimit(RLIMIT_CORE, &rlim) < 0)
182: fatal("setrlimit failed: %.100s", strerror(errno));
183: }
184:
185: /* Use uid-swapping to give up root privileges for the duration of option
186: processing. We will re-instantiate the rights when we are ready to
187: create the privileged port, and will permanently drop them when the
188: port has been created (actually, when the connection has been made, as
189: we may need to create the port several times). */
190: temporarily_use_uid(original_real_uid);
191:
192: /* Set our umask to something reasonable, as some files are created with
193: the default umask. This will make them world-readable but writable
194: only by the owner, which is ok for all files for which we don't set
195: the modes explicitly. */
196: umask(022);
197:
198: /* Save our own name. */
199: av0 = av[0];
200:
201: /* Initialize option structure to indicate that no values have been set. */
202: initialize_options(&options);
203:
204: /* Parse command-line arguments. */
205: host = NULL;
206:
207: /* If program name is not one of the standard names, use it as host name. */
208: if (strchr(av0, '/'))
209: cp = strrchr(av0, '/') + 1;
210: else
211: cp = av0;
212: if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 &&
213: strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0)
214: host = cp;
215:
216: for (optind = 1; optind < ac; optind++)
217: {
218: if (av[optind][0] != '-')
219: {
220: if (host)
221: break;
1.3 deraadt 222: if ((cp = strchr(av[optind], '@'))) {
223: options.user = av[optind];
224: *cp = '\0';
225: host = ++cp;
226: }
227: else
228: host = av[optind];
1.1 deraadt 229: continue;
230: }
231: opt = av[optind][1];
232: if (!opt)
233: usage();
234: if (strchr("eilcpLRo", opt)) /* options with arguments */
235: {
236: optarg = av[optind] + 2;
237: if (strcmp(optarg, "") == 0)
238: {
239: if (optind >= ac - 1)
240: usage();
241: optarg = av[++optind];
242: }
243: }
244: else
245: {
246: if (av[optind][2])
247: usage();
248: optarg = NULL;
249: }
250: switch (opt)
251: {
252: case 'n':
253: stdin_null_flag = 1;
254: break;
255:
256: case 'f':
257: fork_after_authentication_flag = 1;
258: stdin_null_flag = 1;
259: break;
260:
261: case 'x':
262: options.forward_x11 = 0;
263: break;
264:
265: case 'X':
266: options.forward_x11 = 1;
1.4 deraadt 267: break;
268:
269: case 'g':
270: options.gateway_ports = 1;
1.1 deraadt 271: break;
272:
1.23 markus 273: case 'P':
274: options.use_privileged_port = 0;
275: break;
276:
1.1 deraadt 277: case 'a':
278: options.forward_agent = 0;
1.9 dugsong 279: break;
280: #ifdef AFS
281: case 'k':
1.1 deraadt 282: options.kerberos_tgt_passing = 0;
283: options.afs_token_passing = 0;
1.9 dugsong 284: break;
1.1 deraadt 285: #endif
286: case 'i':
287: if (stat(optarg, &st) < 0)
288: {
289: fprintf(stderr, "Warning: Identity file %s does not exist.\n",
290: optarg);
291: break;
292: }
293: if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES)
294: fatal("Too many identity files specified (max %d)",
295: SSH_MAX_IDENTITY_FILES);
296: options.identity_files[options.num_identity_files++] =
297: xstrdup(optarg);
298: break;
299:
300: case 't':
301: tty_flag = 1;
302: break;
303:
304: case 'v':
1.6 deraadt 305: case 'V':
1.1 deraadt 306: fprintf(stderr, "SSH Version %s, protocol version %d.%d.\n",
307: SSH_VERSION, PROTOCOL_MAJOR, PROTOCOL_MINOR);
308: fprintf(stderr, "Compiled with SSL.\n");
1.6 deraadt 309: if (opt == 'V')
310: exit(0);
1.27 markus 311: debug_flag = 1;
312: options.log_level = SYSLOG_LEVEL_DEBUG;
1.1 deraadt 313: break;
314:
315: case 'q':
1.27 markus 316: options.log_level = SYSLOG_LEVEL_QUIET;
1.1 deraadt 317: break;
318:
319: case 'e':
320: if (optarg[0] == '^' && optarg[2] == 0 &&
321: (unsigned char)optarg[1] >= 64 && (unsigned char)optarg[1] < 128)
322: options.escape_char = (unsigned char)optarg[1] & 31;
323: else
324: if (strlen(optarg) == 1)
325: options.escape_char = (unsigned char)optarg[0];
326: else
327: if (strcmp(optarg, "none") == 0)
328: options.escape_char = -2;
329: else
330: {
331: fprintf(stderr, "Bad escape character '%s'.\n", optarg);
332: exit(1);
333: }
334: break;
335:
336: case 'c':
337: options.cipher = cipher_number(optarg);
338: if (options.cipher == -1)
339: {
340: fprintf(stderr, "Unknown cipher type '%s'\n", optarg);
341: exit(1);
342: }
343: break;
344:
345: case 'p':
346: options.port = atoi(optarg);
347: if (options.port < 1 || options.port > 65535)
348: {
349: fprintf(stderr, "Bad port %s.\n", optarg);
350: exit(1);
351: }
352: break;
353:
354: case 'l':
355: options.user = optarg;
356: break;
357:
358: case 'R':
359: if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf,
360: &fwd_host_port) != 3)
361: {
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':
370: if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf,
371: &fwd_host_port) != 3)
372: {
373: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
374: usage();
375: /*NOTREACHED*/
376: }
377: add_local_forward(&options, fwd_port, buf, fwd_host_port);
378: break;
379:
380: case 'C':
381: options.compression = 1;
382: break;
383:
384: case 'o':
385: dummy = 1;
386: process_config_line(&options, host ? host : "", optarg,
387: "command-line", 0, &dummy);
388: break;
389:
390: default:
391: usage();
392: }
393: }
394:
395: /* Check that we got a host name. */
396: if (!host)
397: usage();
1.5 deraadt 398:
399: /* check if RSA support exists */
400: if (rsa_alive() == 0) {
401: extern char *__progname;
402:
403: fprintf(stderr,
404: "%s: no RSA support in libssl and libcrypto. See ssl(8).\n",
405: __progname);
406: exit(1);
407: }
1.1 deraadt 408:
409: /* Initialize the command to execute on remote host. */
410: buffer_init(&command);
411:
412: /* Save the command to execute on the remote host in a buffer. There is
413: no limit on the length of the command, except by the maximum packet
414: size. Also sets the tty flag if there is no command. */
415: if (optind == ac)
416: {
417: /* No command specified - execute shell on a tty. */
418: tty_flag = 1;
419: }
420: else
421: {
422: /* A command has been specified. Store it into the buffer. */
423: for (i = optind; i < ac; i++)
424: {
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: {
442: if (tty_flag)
443: fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n");
444: tty_flag = 0;
445: }
446:
447: /* Get user data. */
448: pw = getpwuid(original_real_uid);
449: if (!pw)
450: {
451: fprintf(stderr, "You don't exist, go away!\n");
452: exit(1);
453: }
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 actually
466: goes to the terminal. */
1.27 markus 467: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
1.1 deraadt 468:
469: /* Read per-user configuration file. */
1.11 deraadt 470: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE);
1.1 deraadt 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);
1.27 markus 478:
479: /* reinit */
480: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
481:
1.1 deraadt 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. */
1.26 markus 504: if (original_effective_uid != 0 || !options.use_privileged_port)
1.1 deraadt 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
1.26 markus 530: rhosts_{rsa_}authentication is enabled. */
1.23 markus 531:
1.22 provos 532: ok = ssh_connect(host, &hostaddr, options.port, options.connection_attempts,
1.1 deraadt 533: !options.rhosts_authentication &&
534: !options.rhosts_rsa_authentication,
1.2 provos 535: original_real_uid, options.proxy_command);
1.1 deraadt 536:
537: /* If we successfully made the connection, load the host private key in
538: case we will need it later for combined rsa-rhosts authentication.
539: This must be done before releasing extra privileges, because the file
540: is only readable by root. */
541: if (ok)
542: {
1.2 provos 543: host_private_key = RSA_new();
544: if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL))
1.1 deraadt 545: host_private_key_loaded = 1;
546: }
547:
548: /* Get rid of any extra privileges that we may have. We will no longer need
549: them. Also, extra privileges could make it very hard to read identity
550: files and other non-world-readable files from the user's home directory
551: if it happens to be on a NFS volume where root is mapped to nobody. */
552: permanently_set_uid(original_real_uid);
553:
554: /* Now that we are back to our own permissions, create ~/.ssh directory
555: if it doesn\'t already exist. */
1.11 deraadt 556: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR);
1.1 deraadt 557: if (stat(buf, &st) < 0)
558: if (mkdir(buf, 0755) < 0)
559: error("Could not create directory '%.200s'.", buf);
560:
561: /* Check if the connection failed, and try "rsh" if appropriate. */
562: if (!ok)
563: {
564: if (options.port != 0)
565: log("Secure connection to %.100s on port %d refused%.100s.",
566: host, options.port,
567: options.fallback_to_rsh ? "; reverting to insecure method" : "");
568: else
569: log("Secure connection to %.100s refused%.100s.", host,
570: options.fallback_to_rsh ? "; reverting to insecure method" : "");
571:
572: if (options.fallback_to_rsh)
573: {
574: rsh_connect(host, options.user, &command);
575: fatal("rsh_connect returned");
576: }
577: exit(1);
578: }
579:
580: /* Expand ~ in options.identity_files. */
581: for (i = 0; i < options.num_identity_files; i++)
582: options.identity_files[i] =
583: tilde_expand_filename(options.identity_files[i], original_real_uid);
584:
585: /* Expand ~ in known host file names. */
586: options.system_hostfile = tilde_expand_filename(options.system_hostfile,
587: original_real_uid);
588: options.user_hostfile = tilde_expand_filename(options.user_hostfile,
589: original_real_uid);
590:
1.2 provos 591: /* Log into the remote system. This never returns if the login fails. */
592: ssh_login(host_private_key_loaded, host_private_key,
1.28 ! markus 593: host, &hostaddr, original_real_uid);
1.1 deraadt 594:
595: /* We no longer need the host private key. Clear it now. */
596: if (host_private_key_loaded)
1.2 provos 597: RSA_free(host_private_key); /* Destroys contents safely */
1.1 deraadt 598:
599: /* Close connection cleanly after attack. */
600: cipher_attack_detected = packet_disconnect;
601:
602: /* If requested, fork and let ssh continue in the background. */
603: if (fork_after_authentication_flag)
604: {
605: int ret = fork();
606: if (ret == -1)
607: fatal("fork failed: %.100s", strerror(errno));
608: if (ret != 0)
609: exit(0);
610: setsid();
611: }
612:
613: /* Enable compression if requested. */
614: if (options.compression)
615: {
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:
635: /* Allocate a pseudo tty if appropriate. */
636: if (tty_flag)
637: {
638: debug("Requesting pty.");
639:
640: /* Start the packet. */
641: packet_start(SSH_CMSG_REQUEST_PTY);
642:
643: /* Store TERM in the packet. There is no limit on the length of the
644: string. */
645: cp = getenv("TERM");
646: if (!cp)
647: cp = "";
648: packet_put_string(cp, strlen(cp));
649:
650: /* Store window size in the packet. */
651: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
652: memset(&ws, 0, sizeof(ws));
653: packet_put_int(ws.ws_row);
654: packet_put_int(ws.ws_col);
655: packet_put_int(ws.ws_xpixel);
656: packet_put_int(ws.ws_ypixel);
657:
658: /* Store tty modes in the packet. */
659: tty_make_modes(fileno(stdin));
660:
661: /* Send the packet, and wait for it to leave. */
662: packet_send();
663: packet_write_wait();
664:
665: /* Read response from the server. */
666: type = packet_read(&plen);
667: if (type == SSH_SMSG_SUCCESS)
668: interactive = 1;
669: else if (type == SSH_SMSG_FAILURE)
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:
675: /* Request X11 forwarding if enabled and DISPLAY is set. */
676: if (options.forward_x11 && getenv("DISPLAY") != NULL)
677: {
678: char line[512], proto[512], data[512];
679: FILE *f;
680: int forwarded = 0, got_data = 0, i;
681:
682: #ifdef XAUTH_PATH
683: /* Try to get Xauthority information for the display. */
1.11 deraadt 684: snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null",
1.1 deraadt 685: XAUTH_PATH, getenv("DISPLAY"));
686: f = popen(line, "r");
687: if (f && fgets(line, sizeof(line), f) &&
688: sscanf(line, "%*s %s %s", proto, data) == 2)
689: got_data = 1;
690: if (f)
691: pclose(f);
692: #endif /* XAUTH_PATH */
693: /* If we didn't get authentication data, just make up some data. The
694: forwarding code will check the validity of the response anyway, and
695: substitute this data. The X11 server, however, will ignore this
696: fake data and use whatever authentication mechanisms it was using
697: otherwise for the local connection. */
698: if (!got_data)
699: {
1.9 dugsong 700: u_int32_t rand = 0;
1.2 provos 701:
1.11 deraadt 702: strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
1.2 provos 703: for (i = 0; i < 16; i++) {
704: if (i % 4 == 0)
705: rand = arc4random();
1.11 deraadt 706: snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
1.2 provos 707: rand >>= 8;
708: }
1.1 deraadt 709: }
710:
711: /* Got local authentication reasonable information. Request forwarding
712: with authentication spoofing. */
713: debug("Requesting X11 forwarding with authentication spoofing.");
1.2 provos 714: x11_request_forwarding_with_spoofing(proto, data);
1.1 deraadt 715:
716: /* Read response from the server. */
717: type = packet_read(&plen);
718: if (type == SSH_SMSG_SUCCESS)
719: {
720: forwarded = 1;
721: interactive = 1;
722: }
723: else if (type == SSH_SMSG_FAILURE)
724: log("Warning: Remote host denied X11 forwarding.");
725: else
726: packet_disconnect("Protocol error waiting for X11 forwarding");
727: }
728:
729: /* Tell the packet module whether this is an interactive session. */
730: packet_set_interactive(interactive, options.keepalives);
731:
732: /* Clear agent forwarding if we don\'t have an agent. */
1.24 markus 733: authfd = ssh_get_authentication_socket();
1.1 deraadt 734: if (authfd < 0)
735: options.forward_agent = 0;
736: else
737: ssh_close_authentication_socket(authfd);
738:
739: /* Request authentication agent forwarding if appropriate. */
740: if (options.forward_agent)
741: {
742: debug("Requesting authentication agent forwarding.");
743: auth_request_forwarding();
744:
745: /* Read response from the server. */
746: type = packet_read(&plen);
747: packet_integrity_check(plen, 0, type);
748: if (type != SSH_SMSG_SUCCESS)
749: log("Warning: Remote host denied authentication agent forwarding.");
750: }
751:
752: /* Initiate local TCP/IP port forwardings. */
753: for (i = 0; i < options.num_local_forwards; i++)
754: {
755: debug("Connections to local port %d forwarded to remote address %.200s:%d",
756: options.local_forwards[i].port, options.local_forwards[i].host,
757: options.local_forwards[i].host_port);
758: channel_request_local_forwarding(options.local_forwards[i].port,
759: options.local_forwards[i].host,
760: options.local_forwards[i].host_port);
761: }
762:
763: /* Initiate remote TCP/IP port forwardings. */
764: for (i = 0; i < options.num_remote_forwards; i++)
765: {
766: debug("Connections to remote port %d forwarded to local address %.200s:%d",
767: options.remote_forwards[i].port, options.remote_forwards[i].host,
768: options.remote_forwards[i].host_port);
769: channel_request_remote_forwarding(options.remote_forwards[i].port,
770: options.remote_forwards[i].host,
771: options.remote_forwards[i].host_port);
772: }
773:
774: /* If a command was specified on the command line, execute the command now.
775: Otherwise request the server to start a shell. */
776: if (buffer_len(&command) > 0)
777: {
778: int len = buffer_len(&command);
779: if (len > 900)
780: len = 900;
781: debug("Sending command: %.*s", len, buffer_ptr(&command));
782: packet_start(SSH_CMSG_EXEC_CMD);
783: packet_put_string(buffer_ptr(&command), buffer_len(&command));
784: packet_send();
785: packet_write_wait();
786: }
787: else
788: {
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. */
796: exit_status = client_loop(tty_flag, tty_flag ? options.escape_char : -1);
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);
803: }
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