Annotation of src/usr.bin/ssh/ssh.c, Revision 1.26
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"
1.26 ! markus 21: RCSID("$Id: ssh.c,v 1.25 1999/10/26 22:38:51 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 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. */
1.11 deraadt 160:
1.2 provos 161: int
162: main(int ac, char **av)
1.1 deraadt 163: {
164: int i, opt, optind, type, exit_status, ok, fwd_port, fwd_host_port, authfd;
165: char *optarg, *cp, buf[256];
166: Buffer command;
167: struct winsize ws;
168: struct stat st;
169: struct passwd *pw, pwcopy;
170: int interactive = 0, dummy;
171: uid_t original_effective_uid;
172: int plen;
173:
174: /* Save the original real uid. It will be needed later (uid-swapping may
175: clobber the real uid). */
176: original_real_uid = getuid();
177: original_effective_uid = geteuid();
178:
179: /* If we are installed setuid root be careful to not drop core. */
180: if (original_real_uid != original_effective_uid)
181: {
182: struct rlimit rlim;
183: rlim.rlim_cur = rlim.rlim_max = 0;
184: if (setrlimit(RLIMIT_CORE, &rlim) < 0)
185: fatal("setrlimit failed: %.100s", strerror(errno));
186: }
187:
188: /* Use uid-swapping to give up root privileges for the duration of option
189: processing. We will re-instantiate the rights when we are ready to
190: create the privileged port, and will permanently drop them when the
191: port has been created (actually, when the connection has been made, as
192: we may need to create the port several times). */
193: temporarily_use_uid(original_real_uid);
194:
195: /* Set our umask to something reasonable, as some files are created with
196: the default umask. This will make them world-readable but writable
197: only by the owner, which is ok for all files for which we don't set
198: the modes explicitly. */
199: umask(022);
200:
201: /* Save our own name. */
202: av0 = av[0];
203:
204: /* Initialize option structure to indicate that no values have been set. */
205: initialize_options(&options);
206:
207: /* Parse command-line arguments. */
208: host = NULL;
209:
210: /* If program name is not one of the standard names, use it as host name. */
211: if (strchr(av0, '/'))
212: cp = strrchr(av0, '/') + 1;
213: else
214: cp = av0;
215: if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 &&
216: strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0)
217: host = cp;
218:
219: for (optind = 1; optind < ac; optind++)
220: {
221: if (av[optind][0] != '-')
222: {
223: if (host)
224: break;
1.3 deraadt 225: if ((cp = strchr(av[optind], '@'))) {
226: options.user = av[optind];
227: *cp = '\0';
228: host = ++cp;
229: }
230: else
231: host = av[optind];
1.1 deraadt 232: continue;
233: }
234: opt = av[optind][1];
235: if (!opt)
236: usage();
237: if (strchr("eilcpLRo", opt)) /* options with arguments */
238: {
239: optarg = av[optind] + 2;
240: if (strcmp(optarg, "") == 0)
241: {
242: if (optind >= ac - 1)
243: usage();
244: optarg = av[++optind];
245: }
246: }
247: else
248: {
249: if (av[optind][2])
250: usage();
251: optarg = NULL;
252: }
253: switch (opt)
254: {
255: case 'n':
256: stdin_null_flag = 1;
257: break;
258:
259: case 'f':
260: fork_after_authentication_flag = 1;
261: stdin_null_flag = 1;
262: break;
263:
264: case 'x':
265: options.forward_x11 = 0;
266: break;
267:
268: case 'X':
269: options.forward_x11 = 1;
1.4 deraadt 270: break;
271:
272: case 'g':
273: options.gateway_ports = 1;
1.1 deraadt 274: break;
275:
1.23 markus 276: case 'P':
277: options.use_privileged_port = 0;
278: break;
279:
1.1 deraadt 280: case 'a':
281: options.forward_agent = 0;
1.9 dugsong 282: break;
283: #ifdef AFS
284: case 'k':
1.1 deraadt 285: options.kerberos_tgt_passing = 0;
286: options.afs_token_passing = 0;
1.9 dugsong 287: break;
1.1 deraadt 288: #endif
289: case 'i':
290: if (stat(optarg, &st) < 0)
291: {
292: fprintf(stderr, "Warning: Identity file %s does not exist.\n",
293: optarg);
294: break;
295: }
296: if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES)
297: fatal("Too many identity files specified (max %d)",
298: SSH_MAX_IDENTITY_FILES);
299: options.identity_files[options.num_identity_files++] =
300: xstrdup(optarg);
301: break;
302:
303: case 't':
304: tty_flag = 1;
305: break;
306:
307: case 'v':
1.6 deraadt 308: case 'V':
1.1 deraadt 309: debug_flag = 1;
310: fprintf(stderr, "SSH Version %s, protocol version %d.%d.\n",
311: SSH_VERSION, PROTOCOL_MAJOR, PROTOCOL_MINOR);
312: fprintf(stderr, "Compiled with SSL.\n");
1.6 deraadt 313: if (opt == 'V')
314: exit(0);
1.1 deraadt 315: break;
316:
317: case 'q':
318: quiet_flag = 1;
319: break;
320:
321: case 'e':
322: if (optarg[0] == '^' && optarg[2] == 0 &&
323: (unsigned char)optarg[1] >= 64 && (unsigned char)optarg[1] < 128)
324: options.escape_char = (unsigned char)optarg[1] & 31;
325: else
326: if (strlen(optarg) == 1)
327: options.escape_char = (unsigned char)optarg[0];
328: else
329: if (strcmp(optarg, "none") == 0)
330: options.escape_char = -2;
331: else
332: {
333: fprintf(stderr, "Bad escape character '%s'.\n", optarg);
334: exit(1);
335: }
336: break;
337:
338: case 'c':
339: options.cipher = cipher_number(optarg);
340: if (options.cipher == -1)
341: {
342: fprintf(stderr, "Unknown cipher type '%s'\n", optarg);
343: exit(1);
344: }
345: break;
346:
347: case 'p':
348: options.port = atoi(optarg);
349: if (options.port < 1 || options.port > 65535)
350: {
351: fprintf(stderr, "Bad port %s.\n", optarg);
352: exit(1);
353: }
354: break;
355:
356: case 'l':
357: options.user = optarg;
358: break;
359:
360: case 'R':
361: if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf,
362: &fwd_host_port) != 3)
363: {
364: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
365: usage();
366: /*NOTREACHED*/
367: }
368: add_remote_forward(&options, fwd_port, buf, fwd_host_port);
369: break;
370:
371: case 'L':
372: if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf,
373: &fwd_host_port) != 3)
374: {
375: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
376: usage();
377: /*NOTREACHED*/
378: }
379: add_local_forward(&options, fwd_port, buf, fwd_host_port);
380: break;
381:
382: case 'C':
383: options.compression = 1;
384: break;
385:
386: case 'o':
387: dummy = 1;
388: process_config_line(&options, host ? host : "", optarg,
389: "command-line", 0, &dummy);
390: break;
391:
392: default:
393: usage();
394: }
395: }
396:
397: /* Check that we got a host name. */
398: if (!host)
399: usage();
1.5 deraadt 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: }
1.1 deraadt 410:
411: /* Initialize the command to execute on remote host. */
412: buffer_init(&command);
413:
414: /* Save the command to execute on the remote host in a buffer. There is
415: no limit on the length of the command, except by the maximum packet
416: size. Also sets the tty flag if there is no command. */
417: if (optind == ac)
418: {
419: /* No command specified - execute shell on a tty. */
420: tty_flag = 1;
421: }
422: else
423: {
424: /* A command has been specified. Store it into the buffer. */
425: for (i = optind; i < ac; i++)
426: {
427: if (i > optind)
428: buffer_append(&command, " ", 1);
429: buffer_append(&command, av[i], strlen(av[i]));
430: }
431: }
432:
433: /* Cannot fork to background if no command. */
434: if (fork_after_authentication_flag && buffer_len(&command) == 0)
435: fatal("Cannot fork into background without a command to execute.");
436:
437: /* Allocate a tty by default if no command specified. */
438: if (buffer_len(&command) == 0)
439: tty_flag = 1;
440:
441: /* Do not allocate a tty if stdin is not a tty. */
442: if (!isatty(fileno(stdin)))
443: {
444: if (tty_flag)
445: fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n");
446: tty_flag = 0;
447: }
448:
449: /* Get user data. */
450: pw = getpwuid(original_real_uid);
451: if (!pw)
452: {
453: fprintf(stderr, "You don't exist, go away!\n");
454: exit(1);
455: }
456:
457: /* Take a copy of the returned structure. */
458: memset(&pwcopy, 0, sizeof(pwcopy));
459: pwcopy.pw_name = xstrdup(pw->pw_name);
460: pwcopy.pw_passwd = xstrdup(pw->pw_passwd);
461: pwcopy.pw_uid = pw->pw_uid;
462: pwcopy.pw_gid = pw->pw_gid;
463: pwcopy.pw_dir = xstrdup(pw->pw_dir);
464: pwcopy.pw_shell = xstrdup(pw->pw_shell);
465: pw = &pwcopy;
466:
467: /* Initialize "log" output. Since we are the client all output actually
468: goes to the terminal. */
469: log_init(av[0], 1, debug_flag, quiet_flag, SYSLOG_FACILITY_USER);
470:
471: /* Read per-user configuration file. */
1.11 deraadt 472: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE);
1.1 deraadt 473: read_config_file(buf, host, &options);
474:
475: /* Read systemwide configuration file. */
476: read_config_file(HOST_CONFIG_FILE, host, &options);
477:
478: /* Fill configuration defaults. */
479: fill_default_options(&options);
480: if (options.user == NULL)
481: options.user = xstrdup(pw->pw_name);
482:
483: if (options.hostname != NULL)
484: host = options.hostname;
485:
486: /* Find canonic host name. */
487: if (strchr(host, '.') == 0)
488: {
489: struct hostent *hp = gethostbyname(host);
490: if (hp != 0)
491: {
492: if (strchr(hp->h_name, '.') != 0)
493: host = xstrdup(hp->h_name);
494: else if (hp->h_aliases != 0
495: && hp->h_aliases[0] != 0
496: && strchr(hp->h_aliases[0], '.') != 0)
497: host = xstrdup(hp->h_aliases[0]);
498: }
499: }
500:
501: /* Disable rhosts authentication if not running as root. */
1.26 ! markus 502: if (original_effective_uid != 0 || !options.use_privileged_port)
1.1 deraadt 503: {
504: options.rhosts_authentication = 0;
505: options.rhosts_rsa_authentication = 0;
506: }
507:
508: /* If using rsh has been selected, exec it now (without trying anything
509: else). Note that we must release privileges first. */
510: if (options.use_rsh)
511: {
512: /* Restore our superuser privileges. This must be done before
513: permanently setting the uid. */
514: restore_uid();
515:
516: /* Switch to the original uid permanently. */
517: permanently_set_uid(original_real_uid);
518:
519: /* Execute rsh. */
520: rsh_connect(host, options.user, &command);
521: fatal("rsh_connect returned");
522: }
523:
524: /* Restore our superuser privileges. */
525: restore_uid();
526:
527: /* Open a connection to the remote host. This needs root privileges if
1.26 ! markus 528: rhosts_{rsa_}authentication is enabled. */
1.23 markus 529:
1.22 provos 530: ok = ssh_connect(host, &hostaddr, options.port, options.connection_attempts,
1.1 deraadt 531: !options.rhosts_authentication &&
532: !options.rhosts_rsa_authentication,
1.2 provos 533: original_real_uid, options.proxy_command);
1.1 deraadt 534:
535: /* If we successfully made the connection, load the host private key in
536: case we will need it later for combined rsa-rhosts authentication.
537: This must be done before releasing extra privileges, because the file
538: is only readable by root. */
539: if (ok)
540: {
1.2 provos 541: host_private_key = RSA_new();
542: if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL))
1.1 deraadt 543: host_private_key_loaded = 1;
544: }
545:
546: /* Get rid of any extra privileges that we may have. We will no longer need
547: them. Also, extra privileges could make it very hard to read identity
548: files and other non-world-readable files from the user's home directory
549: if it happens to be on a NFS volume where root is mapped to nobody. */
550: permanently_set_uid(original_real_uid);
551:
552: /* Now that we are back to our own permissions, create ~/.ssh directory
553: if it doesn\'t already exist. */
1.11 deraadt 554: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR);
1.1 deraadt 555: if (stat(buf, &st) < 0)
556: if (mkdir(buf, 0755) < 0)
557: error("Could not create directory '%.200s'.", buf);
558:
559: /* Check if the connection failed, and try "rsh" if appropriate. */
560: if (!ok)
561: {
562: if (options.port != 0)
563: log("Secure connection to %.100s on port %d refused%.100s.",
564: host, options.port,
565: options.fallback_to_rsh ? "; reverting to insecure method" : "");
566: else
567: log("Secure connection to %.100s refused%.100s.", host,
568: options.fallback_to_rsh ? "; reverting to insecure method" : "");
569:
570: if (options.fallback_to_rsh)
571: {
572: rsh_connect(host, options.user, &command);
573: fatal("rsh_connect returned");
574: }
575: exit(1);
576: }
577:
578: /* Expand ~ in options.identity_files. */
579: for (i = 0; i < options.num_identity_files; i++)
580: options.identity_files[i] =
581: tilde_expand_filename(options.identity_files[i], original_real_uid);
582:
583: /* Expand ~ in known host file names. */
584: options.system_hostfile = tilde_expand_filename(options.system_hostfile,
585: original_real_uid);
586: options.user_hostfile = tilde_expand_filename(options.user_hostfile,
587: original_real_uid);
588:
1.2 provos 589: /* Log into the remote system. This never returns if the login fails. */
590: ssh_login(host_private_key_loaded, host_private_key,
1.22 provos 591: host, &hostaddr, &options, original_real_uid);
1.1 deraadt 592:
593: /* We no longer need the host private key. Clear it now. */
594: if (host_private_key_loaded)
1.2 provos 595: RSA_free(host_private_key); /* Destroys contents safely */
1.1 deraadt 596:
597: /* Close connection cleanly after attack. */
598: cipher_attack_detected = packet_disconnect;
599:
600: /* If requested, fork and let ssh continue in the background. */
601: if (fork_after_authentication_flag)
602: {
603: int ret = fork();
604: if (ret == -1)
605: fatal("fork failed: %.100s", strerror(errno));
606: if (ret != 0)
607: exit(0);
608: setsid();
609: }
610:
611: /* Enable compression if requested. */
612: if (options.compression)
613: {
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:
633: /* Allocate a pseudo tty if appropriate. */
634: if (tty_flag)
635: {
636: debug("Requesting pty.");
637:
638: /* Start the packet. */
639: packet_start(SSH_CMSG_REQUEST_PTY);
640:
641: /* Store TERM in the packet. There is no limit on the length of the
642: string. */
643: cp = getenv("TERM");
644: if (!cp)
645: cp = "";
646: packet_put_string(cp, strlen(cp));
647:
648: /* Store window size in the packet. */
649: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
650: memset(&ws, 0, sizeof(ws));
651: packet_put_int(ws.ws_row);
652: packet_put_int(ws.ws_col);
653: packet_put_int(ws.ws_xpixel);
654: packet_put_int(ws.ws_ypixel);
655:
656: /* Store tty modes in the packet. */
657: tty_make_modes(fileno(stdin));
658:
659: /* Send the packet, and wait for it to leave. */
660: packet_send();
661: packet_write_wait();
662:
663: /* Read response from the server. */
664: type = packet_read(&plen);
665: if (type == SSH_SMSG_SUCCESS)
666: interactive = 1;
667: else if (type == SSH_SMSG_FAILURE)
668: log("Warning: Remote host failed or refused to allocate a pseudo tty.");
669: else
670: packet_disconnect("Protocol error waiting for pty request response.");
671: }
672:
673: /* Request X11 forwarding if enabled and DISPLAY is set. */
674: if (options.forward_x11 && getenv("DISPLAY") != NULL)
675: {
676: char line[512], proto[512], data[512];
677: FILE *f;
678: int forwarded = 0, got_data = 0, i;
679:
680: #ifdef XAUTH_PATH
681: /* Try to get Xauthority information for the display. */
1.11 deraadt 682: snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null",
1.1 deraadt 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);
690: #endif /* XAUTH_PATH */
691: /* If we didn't get authentication data, just make up some data. The
692: forwarding code will check the validity of the response anyway, and
693: substitute this data. The X11 server, however, will ignore this
694: fake data and use whatever authentication mechanisms it was using
695: otherwise for the local connection. */
696: if (!got_data)
697: {
1.9 dugsong 698: u_int32_t rand = 0;
1.2 provos 699:
1.11 deraadt 700: strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
1.2 provos 701: for (i = 0; i < 16; i++) {
702: if (i % 4 == 0)
703: rand = arc4random();
1.11 deraadt 704: snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
1.2 provos 705: rand >>= 8;
706: }
1.1 deraadt 707: }
708:
709: /* Got local authentication reasonable information. Request forwarding
710: with authentication spoofing. */
711: debug("Requesting X11 forwarding with authentication spoofing.");
1.2 provos 712: x11_request_forwarding_with_spoofing(proto, data);
1.1 deraadt 713:
714: /* Read response from the server. */
715: type = packet_read(&plen);
716: if (type == SSH_SMSG_SUCCESS)
717: {
718: forwarded = 1;
719: interactive = 1;
720: }
721: else if (type == SSH_SMSG_FAILURE)
722: log("Warning: Remote host denied X11 forwarding.");
723: else
724: packet_disconnect("Protocol error waiting for X11 forwarding");
725: }
726:
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. */
1.24 markus 731: authfd = ssh_get_authentication_socket();
1.1 deraadt 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: {
740: debug("Requesting authentication agent forwarding.");
741: auth_request_forwarding();
742:
743: /* Read response from the server. */
744: type = packet_read(&plen);
745: packet_integrity_check(plen, 0, type);
746: if (type != SSH_SMSG_SUCCESS)
747: log("Warning: Remote host denied authentication agent forwarding.");
748: }
749:
750: /* Initiate local TCP/IP port forwardings. */
751: for (i = 0; i < options.num_local_forwards; i++)
752: {
753: debug("Connections to local port %d forwarded to remote address %.200s:%d",
754: options.local_forwards[i].port, options.local_forwards[i].host,
755: options.local_forwards[i].host_port);
756: channel_request_local_forwarding(options.local_forwards[i].port,
757: options.local_forwards[i].host,
758: options.local_forwards[i].host_port);
759: }
760:
761: /* Initiate remote TCP/IP port forwardings. */
762: for (i = 0; i < options.num_remote_forwards; i++)
763: {
764: debug("Connections to remote port %d forwarded to local address %.200s:%d",
765: options.remote_forwards[i].port, options.remote_forwards[i].host,
766: options.remote_forwards[i].host_port);
767: channel_request_remote_forwarding(options.remote_forwards[i].port,
768: options.remote_forwards[i].host,
769: options.remote_forwards[i].host_port);
770: }
771:
772: /* If a command was specified on the command line, execute the command now.
773: Otherwise request the server to start a shell. */
774: if (buffer_len(&command) > 0)
775: {
776: int len = buffer_len(&command);
777: if (len > 900)
778: len = 900;
779: debug("Sending command: %.*s", len, buffer_ptr(&command));
780: packet_start(SSH_CMSG_EXEC_CMD);
781: packet_put_string(buffer_ptr(&command), buffer_len(&command));
782: packet_send();
783: packet_write_wait();
784: }
785: else
786: {
787: debug("Requesting shell.");
788: packet_start(SSH_CMSG_EXEC_SHELL);
789: packet_send();
790: packet_write_wait();
791: }
792:
793: /* Enter the interactive session. */
794: exit_status = client_loop(tty_flag, tty_flag ? options.escape_char : -1);
795:
796: /* Close the connection to the remote host. */
797: packet_close();
798:
799: /* Exit with the status returned by the program on the remote side. */
800: exit(exit_status);
801: }