Annotation of src/usr.bin/ssh/ssh.c, Revision 1.31
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"
1.31 ! markus 21: RCSID("$Id: ssh.c,v 1.30 1999/11/15 21:05:03 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:
1.31 ! markus 31: /* Flag indicating whether debug mode is on. This can be set on the command line. */
1.1 deraadt 32: int debug_flag = 0;
33:
1.31 ! markus 34: /* Flag indicating whether to allocate a pseudo tty. This can be set on the command
! 35: line, and is automatically set if no command is given on the command line. */
1.1 deraadt 36: int tty_flag = 0;
37:
38: /* Flag indicating that nothing should be read from stdin. This can be set
39: on the command line. */
40: int stdin_null_flag = 0;
41:
42: /* Flag indicating that ssh should fork after authentication. This is useful
43: so that the pasphrase can be entered manually, and then ssh goes to the
44: background. */
45: int fork_after_authentication_flag = 0;
46:
47: /* General data structure for command line options and options configurable
48: in configuration files. See readconf.h. */
49: Options options;
50:
51: /* Name of the host we are connecting to. This is the name given on the
52: command line, or the HostName specified for the user-supplied name
53: in a configuration file. */
54: char *host;
55:
1.22 provos 56: /* socket address the host resolves to */
57: struct sockaddr_in hostaddr;
58:
1.1 deraadt 59: /* Flag to indicate that we have received a window change signal which has
60: not yet been processed. This will cause a message indicating the new
61: window size to be sent to the server a little later. This is volatile
62: because this is updated in a signal handler. */
63: volatile int received_window_change_signal = 0;
64:
65: /* Value of argv[0] (set in the main program). */
66: char *av0;
67:
68: /* Flag indicating whether we have a valid host private key loaded. */
69: int host_private_key_loaded = 0;
70:
71: /* Host private key. */
1.2 provos 72: RSA *host_private_key = NULL;
1.1 deraadt 73:
1.10 dugsong 74: /* Original real UID. */
75: uid_t original_real_uid;
1.1 deraadt 76:
77: /* Prints a help message to the user. This function never returns. */
78:
1.2 provos 79: void
80: usage()
1.1 deraadt 81: {
1.31 ! markus 82: fprintf(stderr, "Usage: %s [options] host [command]\n", av0);
! 83: fprintf(stderr, "Options:\n");
! 84: fprintf(stderr, " -l user Log in using this user name.\n");
! 85: fprintf(stderr, " -n Redirect input from /dev/null.\n");
! 86: fprintf(stderr, " -a Disable authentication agent forwarding.\n");
1.9 dugsong 87: #ifdef AFS
1.31 ! markus 88: fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n");
! 89: #endif /* AFS */
! 90: fprintf(stderr, " -x Disable X11 connection forwarding.\n");
! 91: fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n");
! 92: fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n");
! 93: fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
! 94: fprintf(stderr, " -V Display version number only.\n");
! 95: fprintf(stderr, " -P Don't allocate a privileged port.\n");
! 96: fprintf(stderr, " -q Quiet; don't display any warning messages.\n");
! 97: fprintf(stderr, " -f Fork into background after authentication.\n");
! 98: fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n");
! 99:
! 100: fprintf(stderr, " -c cipher Select encryption algorithm: "
! 101: "``3des'', "
! 102: "``blowfish''\n");
! 103: fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n");
! 104: fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n");
! 105: fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n");
! 106: fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0);
! 107: fprintf(stderr, " forward them to the other side by connecting to host:port.\n");
! 108: fprintf(stderr, " -C Enable compression.\n");
! 109: fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n");
! 110: fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n");
! 111: exit(1);
1.1 deraadt 112: }
113:
114: /* Connects to the given host using rsh (or prints an error message and exits
115: if rsh is not available). This function never returns. */
116:
1.2 provos 117: void
1.31 ! markus 118: rsh_connect(char *host, char *user, Buffer * command)
1.1 deraadt 119: {
1.31 ! markus 120: char *args[10];
! 121: int i;
! 122:
! 123: log("Using rsh. WARNING: Connection will not be encrypted.");
! 124: /* Build argument list for rsh. */
! 125: i = 0;
! 126: args[i++] = _PATH_RSH;
! 127: /* host may have to come after user on some systems */
! 128: args[i++] = host;
! 129: if (user) {
! 130: args[i++] = "-l";
! 131: args[i++] = user;
! 132: }
! 133: if (buffer_len(command) > 0) {
! 134: buffer_append(command, "\0", 1);
! 135: args[i++] = buffer_ptr(command);
! 136: }
! 137: args[i++] = NULL;
! 138: if (debug_flag) {
! 139: for (i = 0; args[i]; i++) {
! 140: if (i != 0)
! 141: fprintf(stderr, " ");
! 142: fprintf(stderr, "%s", args[i]);
! 143: }
! 144: fprintf(stderr, "\n");
! 145: }
! 146: execv(_PATH_RSH, args);
! 147: perror(_PATH_RSH);
! 148: exit(1);
1.1 deraadt 149: }
150:
151: /* Main program for the ssh client. */
1.11 deraadt 152:
1.2 provos 153: int
154: main(int ac, char **av)
1.1 deraadt 155: {
1.31 ! markus 156: int i, opt, optind, type, exit_status, ok, fwd_port, fwd_host_port,
! 157: authfd;
! 158: char *optarg, *cp, buf[256];
! 159: Buffer command;
! 160: struct winsize ws;
! 161: struct stat st;
! 162: struct passwd *pw, pwcopy;
! 163: int interactive = 0, dummy;
! 164: uid_t original_effective_uid;
! 165: int plen;
! 166:
! 167: /* Save the original real uid. It will be needed later
! 168: (uid-swapping may clobber the real uid). */
! 169: original_real_uid = getuid();
! 170: original_effective_uid = geteuid();
! 171:
! 172: /* If we are installed setuid root be careful to not drop core. */
! 173: if (original_real_uid != original_effective_uid) {
! 174: struct rlimit rlim;
! 175: rlim.rlim_cur = rlim.rlim_max = 0;
! 176: if (setrlimit(RLIMIT_CORE, &rlim) < 0)
! 177: fatal("setrlimit failed: %.100s", strerror(errno));
1.1 deraadt 178: }
1.31 ! markus 179: /* Use uid-swapping to give up root privileges for the duration of
! 180: option processing. We will re-instantiate the rights when we
! 181: are ready to create the privileged port, and will permanently
! 182: drop them when the port has been created (actually, when the
! 183: connection has been made, as we may need to create the port
! 184: several times). */
! 185: temporarily_use_uid(original_real_uid);
! 186:
! 187: /* Set our umask to something reasonable, as some files are
! 188: created with the default umask. This will make them
! 189: world-readable but writable only by the owner, which is ok for
! 190: all files for which we don't set the modes explicitly. */
! 191: umask(022);
! 192:
! 193: /* Save our own name. */
! 194: av0 = av[0];
! 195:
! 196: /* Initialize option structure to indicate that no values have been set. */
! 197: initialize_options(&options);
! 198:
! 199: /* Parse command-line arguments. */
! 200: host = NULL;
! 201:
! 202: /* If program name is not one of the standard names, use it as host name. */
! 203: if (strchr(av0, '/'))
! 204: cp = strrchr(av0, '/') + 1;
! 205: else
! 206: cp = av0;
! 207: if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 &&
! 208: strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0)
! 209: host = cp;
! 210:
! 211: for (optind = 1; optind < ac; optind++) {
! 212: if (av[optind][0] != '-') {
! 213: if (host)
! 214: break;
! 215: if ((cp = strchr(av[optind], '@'))) {
! 216: options.user = av[optind];
! 217: *cp = '\0';
! 218: host = ++cp;
! 219: } else
! 220: host = av[optind];
! 221: continue;
! 222: }
! 223: opt = av[optind][1];
! 224: if (!opt)
! 225: usage();
! 226: if (strchr("eilcpLRo", opt)) { /* options with arguments */
! 227: optarg = av[optind] + 2;
! 228: if (strcmp(optarg, "") == 0) {
! 229: if (optind >= ac - 1)
! 230: usage();
! 231: optarg = av[++optind];
! 232: }
! 233: } else {
! 234: if (av[optind][2])
! 235: usage();
! 236: optarg = NULL;
! 237: }
! 238: switch (opt) {
! 239: case 'n':
! 240: stdin_null_flag = 1;
! 241: break;
! 242:
! 243: case 'f':
! 244: fork_after_authentication_flag = 1;
! 245: stdin_null_flag = 1;
! 246: break;
! 247:
! 248: case 'x':
! 249: options.forward_x11 = 0;
! 250: break;
! 251:
! 252: case 'X':
! 253: options.forward_x11 = 1;
! 254: break;
! 255:
! 256: case 'g':
! 257: options.gateway_ports = 1;
! 258: break;
! 259:
! 260: case 'P':
! 261: options.use_privileged_port = 0;
! 262: break;
! 263:
! 264: case 'a':
! 265: options.forward_agent = 0;
! 266: break;
1.9 dugsong 267: #ifdef AFS
1.31 ! markus 268: case 'k':
! 269: options.kerberos_tgt_passing = 0;
! 270: options.afs_token_passing = 0;
! 271: break;
1.1 deraadt 272: #endif
1.31 ! markus 273: case 'i':
! 274: if (stat(optarg, &st) < 0) {
! 275: fprintf(stderr, "Warning: Identity file %s does not exist.\n",
! 276: optarg);
! 277: break;
! 278: }
! 279: if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES)
! 280: fatal("Too many identity files specified (max %d)",
! 281: SSH_MAX_IDENTITY_FILES);
! 282: options.identity_files[options.num_identity_files++] =
! 283: xstrdup(optarg);
! 284: break;
! 285:
! 286: case 't':
! 287: tty_flag = 1;
! 288: break;
! 289:
! 290: case 'v':
! 291: case 'V':
! 292: fprintf(stderr, "SSH Version %s, protocol version %d.%d.\n",
! 293: SSH_VERSION, PROTOCOL_MAJOR, PROTOCOL_MINOR);
! 294: fprintf(stderr, "Compiled with SSL.\n");
! 295: if (opt == 'V')
! 296: exit(0);
! 297: debug_flag = 1;
! 298: options.log_level = SYSLOG_LEVEL_DEBUG;
! 299: break;
! 300:
! 301: case 'q':
! 302: options.log_level = SYSLOG_LEVEL_QUIET;
! 303: break;
! 304:
! 305: case 'e':
! 306: if (optarg[0] == '^' && optarg[2] == 0 &&
! 307: (unsigned char) optarg[1] >= 64 && (unsigned char) optarg[1] < 128)
! 308: options.escape_char = (unsigned char) optarg[1] & 31;
! 309: else if (strlen(optarg) == 1)
! 310: options.escape_char = (unsigned char) optarg[0];
! 311: else if (strcmp(optarg, "none") == 0)
! 312: options.escape_char = -2;
! 313: else {
! 314: fprintf(stderr, "Bad escape character '%s'.\n", optarg);
! 315: exit(1);
! 316: }
! 317: break;
! 318:
! 319: case 'c':
! 320: options.cipher = cipher_number(optarg);
! 321: if (options.cipher == -1) {
! 322: fprintf(stderr, "Unknown cipher type '%s'\n", optarg);
! 323: exit(1);
! 324: }
! 325: break;
! 326:
! 327: case 'p':
! 328: options.port = atoi(optarg);
! 329: if (options.port < 1 || options.port > 65535) {
! 330: fprintf(stderr, "Bad port %s.\n", optarg);
! 331: exit(1);
! 332: }
! 333: break;
! 334:
! 335: case 'l':
! 336: options.user = optarg;
! 337: break;
! 338:
! 339: case 'R':
! 340: if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf,
! 341: &fwd_host_port) != 3) {
! 342: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
! 343: usage();
! 344: /* NOTREACHED */
! 345: }
! 346: add_remote_forward(&options, fwd_port, buf, fwd_host_port);
! 347: break;
! 348:
! 349: case 'L':
! 350: if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf,
! 351: &fwd_host_port) != 3) {
! 352: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
! 353: usage();
! 354: /* NOTREACHED */
! 355: }
! 356: add_local_forward(&options, fwd_port, buf, fwd_host_port);
! 357: break;
! 358:
! 359: case 'C':
! 360: options.compression = 1;
! 361: break;
! 362:
! 363: case 'o':
! 364: dummy = 1;
! 365: if (process_config_line(&options, host ? host : "", optarg,
! 366: "command-line", 0, &dummy) != 0)
! 367: exit(1);
! 368: break;
! 369:
! 370: default:
! 371: usage();
1.1 deraadt 372: }
1.31 ! markus 373: }
! 374:
! 375: /* Check that we got a host name. */
! 376: if (!host)
! 377: usage();
! 378:
! 379: /* check if RSA support exists */
! 380: if (rsa_alive() == 0) {
! 381: extern char *__progname;
! 382:
! 383: fprintf(stderr,
! 384: "%s: no RSA support in libssl and libcrypto. See ssl(8).\n",
! 385: __progname);
! 386: exit(1);
! 387: }
! 388: /* Initialize the command to execute on remote host. */
! 389: buffer_init(&command);
1.1 deraadt 390:
1.31 ! markus 391: /* Save the command to execute on the remote host in a buffer.
! 392: There is no limit on the length of the command, except by the
! 393: maximum packet size. Also sets the tty flag if there is no
! 394: command. */
! 395: if (optind == ac) {
! 396: /* No command specified - execute shell on a tty. */
! 397: tty_flag = 1;
! 398: } else {
! 399: /* A command has been specified. Store it into the
! 400: buffer. */
! 401: for (i = optind; i < ac; i++) {
! 402: if (i > optind)
! 403: buffer_append(&command, " ", 1);
! 404: buffer_append(&command, av[i], strlen(av[i]));
! 405: }
! 406: }
! 407:
! 408: /* Cannot fork to background if no command. */
! 409: if (fork_after_authentication_flag && buffer_len(&command) == 0)
! 410: fatal("Cannot fork into background without a command to execute.");
! 411:
! 412: /* Allocate a tty by default if no command specified. */
! 413: if (buffer_len(&command) == 0)
! 414: tty_flag = 1;
! 415:
! 416: /* Do not allocate a tty if stdin is not a tty. */
! 417: if (!isatty(fileno(stdin))) {
! 418: if (tty_flag)
! 419: fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n");
! 420: tty_flag = 0;
! 421: }
! 422: /* Get user data. */
! 423: pw = getpwuid(original_real_uid);
! 424: if (!pw) {
! 425: fprintf(stderr, "You don't exist, go away!\n");
! 426: exit(1);
! 427: }
! 428: /* Take a copy of the returned structure. */
! 429: memset(&pwcopy, 0, sizeof(pwcopy));
! 430: pwcopy.pw_name = xstrdup(pw->pw_name);
! 431: pwcopy.pw_passwd = xstrdup(pw->pw_passwd);
! 432: pwcopy.pw_uid = pw->pw_uid;
! 433: pwcopy.pw_gid = pw->pw_gid;
! 434: pwcopy.pw_dir = xstrdup(pw->pw_dir);
! 435: pwcopy.pw_shell = xstrdup(pw->pw_shell);
! 436: pw = &pwcopy;
! 437:
! 438: /* Initialize "log" output. Since we are the client all output
! 439: actually goes to the terminal. */
! 440: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
! 441:
! 442: /* Read per-user configuration file. */
! 443: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE);
! 444: read_config_file(buf, host, &options);
! 445:
! 446: /* Read systemwide configuration file. */
! 447: read_config_file(HOST_CONFIG_FILE, host, &options);
! 448:
! 449: /* Fill configuration defaults. */
! 450: fill_default_options(&options);
! 451:
! 452: /* reinit */
! 453: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
! 454:
! 455: if (options.user == NULL)
! 456: options.user = xstrdup(pw->pw_name);
! 457:
! 458: if (options.hostname != NULL)
! 459: host = options.hostname;
! 460:
! 461: /* Find canonic host name. */
! 462: if (strchr(host, '.') == 0) {
! 463: struct hostent *hp = gethostbyname(host);
! 464: if (hp != 0) {
! 465: if (strchr(hp->h_name, '.') != 0)
! 466: host = xstrdup(hp->h_name);
! 467: else if (hp->h_aliases != 0
! 468: && hp->h_aliases[0] != 0
! 469: && strchr(hp->h_aliases[0], '.') != 0)
! 470: host = xstrdup(hp->h_aliases[0]);
! 471: }
! 472: }
! 473: /* Disable rhosts authentication if not running as root. */
! 474: if (original_effective_uid != 0 || !options.use_privileged_port) {
! 475: options.rhosts_authentication = 0;
! 476: options.rhosts_rsa_authentication = 0;
! 477: }
! 478: /* If using rsh has been selected, exec it now (without trying
! 479: anything else). Note that we must release privileges first. */
! 480: if (options.use_rsh) {
! 481: /* Restore our superuser privileges. This must be done
! 482: before permanently setting the uid. */
! 483: restore_uid();
! 484:
! 485: /* Switch to the original uid permanently. */
! 486: permanently_set_uid(original_real_uid);
! 487:
! 488: /* Execute rsh. */
! 489: rsh_connect(host, options.user, &command);
! 490: fatal("rsh_connect returned");
! 491: }
! 492: /* Restore our superuser privileges. */
! 493: restore_uid();
! 494:
! 495: /* Open a connection to the remote host. This needs root
! 496: privileges if rhosts_{rsa_}authentication is enabled. */
! 497:
! 498: ok = ssh_connect(host, &hostaddr, options.port,
! 499: options.connection_attempts,
! 500: !options.rhosts_authentication &&
! 501: !options.rhosts_rsa_authentication,
! 502: original_real_uid,
! 503: options.proxy_command);
! 504:
! 505: /* If we successfully made the connection, load the host private
! 506: key in case we will need it later for combined rsa-rhosts
! 507: authentication. This must be done before releasing extra
! 508: privileges, because the file is only readable by root. */
! 509: if (ok) {
! 510: host_private_key = RSA_new();
! 511: if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL))
! 512: host_private_key_loaded = 1;
! 513: }
! 514: /* Get rid of any extra privileges that we may have. We will no
! 515: longer need them. Also, extra privileges could make it very
! 516: hard to read identity files and other non-world-readable files
! 517: from the user's home directory if it happens to be on a NFS
! 518: volume where root is mapped to nobody. */
! 519:
! 520: /* Note that some legacy systems need to postpone the following
! 521: call to permanently_set_uid() until the private hostkey is
! 522: destroyed with RSA_free(). Otherwise the calling user could
! 523: ptrace() the process, read the private hostkey and impersonate
! 524: the host. OpenBSD does not allow ptracing of setuid processes. */
! 525:
! 526: permanently_set_uid(original_real_uid);
! 527:
! 528: /* Now that we are back to our own permissions, create ~/.ssh
! 529: directory if it doesn\'t already exist. */
! 530: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR);
! 531: if (stat(buf, &st) < 0)
! 532: if (mkdir(buf, 0755) < 0)
! 533: error("Could not create directory '%.200s'.", buf);
! 534:
! 535: /* Check if the connection failed, and try "rsh" if appropriate. */
! 536: if (!ok) {
! 537: if (options.port != 0)
! 538: log("Secure connection to %.100s on port %d refused%.100s.",
! 539: host, options.port,
! 540: options.fallback_to_rsh ? "; reverting to insecure method" : "");
! 541: else
! 542: log("Secure connection to %.100s refused%.100s.", host,
! 543: options.fallback_to_rsh ? "; reverting to insecure method" : "");
! 544:
! 545: if (options.fallback_to_rsh) {
! 546: rsh_connect(host, options.user, &command);
! 547: fatal("rsh_connect returned");
! 548: }
! 549: exit(1);
! 550: }
! 551: /* Expand ~ in options.identity_files. */
! 552: for (i = 0; i < options.num_identity_files; i++)
! 553: options.identity_files[i] =
! 554: tilde_expand_filename(options.identity_files[i], original_real_uid);
! 555:
! 556: /* Expand ~ in known host file names. */
! 557: options.system_hostfile = tilde_expand_filename(options.system_hostfile,
! 558: original_real_uid);
! 559: options.user_hostfile = tilde_expand_filename(options.user_hostfile,
! 560: original_real_uid);
! 561:
! 562: /* Log into the remote system. This never returns if the login fails. */
! 563: ssh_login(host_private_key_loaded, host_private_key,
! 564: host, &hostaddr, original_real_uid);
! 565:
! 566: /* We no longer need the host private key. Clear it now. */
! 567: if (host_private_key_loaded)
! 568: RSA_free(host_private_key); /* Destroys contents safely */
! 569:
! 570: /* Close connection cleanly after attack. */
! 571: cipher_attack_detected = packet_disconnect;
! 572:
! 573: /* If requested, fork and let ssh continue in the background. */
! 574: if (fork_after_authentication_flag) {
! 575: int ret = fork();
! 576: if (ret == -1)
! 577: fatal("fork failed: %.100s", strerror(errno));
! 578: if (ret != 0)
! 579: exit(0);
! 580: setsid();
! 581: }
! 582: /* Enable compression if requested. */
! 583: if (options.compression) {
! 584: debug("Requesting compression at level %d.", options.compression_level);
! 585:
! 586: if (options.compression_level < 1 || options.compression_level > 9)
! 587: fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
! 588:
! 589: /* Send the request. */
! 590: packet_start(SSH_CMSG_REQUEST_COMPRESSION);
! 591: packet_put_int(options.compression_level);
! 592: packet_send();
! 593: packet_write_wait();
! 594: type = packet_read(&plen);
! 595: if (type == SSH_SMSG_SUCCESS)
! 596: packet_start_compression(options.compression_level);
! 597: else if (type == SSH_SMSG_FAILURE)
! 598: log("Warning: Remote host refused compression.");
! 599: else
! 600: packet_disconnect("Protocol error waiting for compression response.");
! 601: }
! 602: /* Allocate a pseudo tty if appropriate. */
! 603: if (tty_flag) {
! 604: debug("Requesting pty.");
! 605:
! 606: /* Start the packet. */
! 607: packet_start(SSH_CMSG_REQUEST_PTY);
! 608:
! 609: /* Store TERM in the packet. There is no limit on the
! 610: length of the string. */
! 611: cp = getenv("TERM");
! 612: if (!cp)
! 613: cp = "";
! 614: packet_put_string(cp, strlen(cp));
! 615:
! 616: /* Store window size in the packet. */
! 617: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
! 618: memset(&ws, 0, sizeof(ws));
! 619: packet_put_int(ws.ws_row);
! 620: packet_put_int(ws.ws_col);
! 621: packet_put_int(ws.ws_xpixel);
! 622: packet_put_int(ws.ws_ypixel);
! 623:
! 624: /* Store tty modes in the packet. */
! 625: tty_make_modes(fileno(stdin));
! 626:
! 627: /* Send the packet, and wait for it to leave. */
! 628: packet_send();
! 629: packet_write_wait();
! 630:
! 631: /* Read response from the server. */
! 632: type = packet_read(&plen);
! 633: if (type == SSH_SMSG_SUCCESS)
! 634: interactive = 1;
! 635: else if (type == SSH_SMSG_FAILURE)
! 636: log("Warning: Remote host failed or refused to allocate a pseudo tty.");
! 637: else
! 638: packet_disconnect("Protocol error waiting for pty request response.");
! 639: }
! 640: /* Request X11 forwarding if enabled and DISPLAY is set. */
! 641: if (options.forward_x11 && getenv("DISPLAY") != NULL) {
! 642: char line[512], proto[512], data[512];
! 643: FILE *f;
! 644: int forwarded = 0, got_data = 0, i;
1.1 deraadt 645:
646: #ifdef XAUTH_PATH
1.31 ! markus 647: /* Try to get Xauthority information for the display. */
! 648: snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null",
! 649: XAUTH_PATH, getenv("DISPLAY"));
! 650: f = popen(line, "r");
! 651: if (f && fgets(line, sizeof(line), f) &&
! 652: sscanf(line, "%*s %s %s", proto, data) == 2)
! 653: got_data = 1;
! 654: if (f)
! 655: pclose(f);
1.1 deraadt 656: #endif /* XAUTH_PATH */
1.31 ! markus 657: /* If we didn't get authentication data, just make up some
! 658: data. The forwarding code will check the validity of
! 659: the response anyway, and substitute this data. The X11
! 660: server, however, will ignore this fake data and use
! 661: whatever authentication mechanisms it was using
! 662: otherwise for the local connection. */
! 663: if (!got_data) {
! 664: u_int32_t rand = 0;
! 665:
! 666: strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
! 667: for (i = 0; i < 16; i++) {
! 668: if (i % 4 == 0)
! 669: rand = arc4random();
! 670: snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
! 671: rand >>= 8;
! 672: }
! 673: }
! 674: /* Got local authentication reasonable information.
! 675: Request forwarding with authentication spoofing. */
! 676: debug("Requesting X11 forwarding with authentication spoofing.");
! 677: x11_request_forwarding_with_spoofing(proto, data);
! 678:
! 679: /* Read response from the server. */
! 680: type = packet_read(&plen);
! 681: if (type == SSH_SMSG_SUCCESS) {
! 682: forwarded = 1;
! 683: interactive = 1;
! 684: } else if (type == SSH_SMSG_FAILURE)
! 685: log("Warning: Remote host denied X11 forwarding.");
! 686: else
! 687: packet_disconnect("Protocol error waiting for X11 forwarding");
! 688: }
! 689: /* Tell the packet module whether this is an interactive session. */
! 690: packet_set_interactive(interactive, options.keepalives);
! 691:
! 692: /* Clear agent forwarding if we don\'t have an agent. */
! 693: authfd = ssh_get_authentication_socket();
! 694: if (authfd < 0)
! 695: options.forward_agent = 0;
! 696: else
! 697: ssh_close_authentication_socket(authfd);
! 698:
! 699: /* Request authentication agent forwarding if appropriate. */
! 700: if (options.forward_agent) {
! 701: debug("Requesting authentication agent forwarding.");
! 702: auth_request_forwarding();
! 703:
! 704: /* Read response from the server. */
! 705: type = packet_read(&plen);
! 706: packet_integrity_check(plen, 0, type);
! 707: if (type != SSH_SMSG_SUCCESS)
! 708: log("Warning: Remote host denied authentication agent forwarding.");
! 709: }
! 710: /* Initiate local TCP/IP port forwardings. */
! 711: for (i = 0; i < options.num_local_forwards; i++) {
! 712: debug("Connections to local port %d forwarded to remote address %.200s:%d",
! 713: options.local_forwards[i].port,
! 714: options.local_forwards[i].host,
! 715: options.local_forwards[i].host_port);
! 716: channel_request_local_forwarding(options.local_forwards[i].port,
! 717: options.local_forwards[i].host,
! 718: options.local_forwards[i].host_port);
! 719: }
! 720:
! 721: /* Initiate remote TCP/IP port forwardings. */
! 722: for (i = 0; i < options.num_remote_forwards; i++) {
! 723: debug("Connections to remote port %d forwarded to local address %.200s:%d",
! 724: options.remote_forwards[i].port,
! 725: options.remote_forwards[i].host,
! 726: options.remote_forwards[i].host_port);
! 727: channel_request_remote_forwarding(options.remote_forwards[i].port,
! 728: options.remote_forwards[i].host,
! 729: options.remote_forwards[i].host_port);
! 730: }
! 731:
! 732: /* If a command was specified on the command line, execute the
! 733: command now. Otherwise request the server to start a shell. */
! 734: if (buffer_len(&command) > 0) {
! 735: int len = buffer_len(&command);
! 736: if (len > 900)
! 737: len = 900;
! 738: debug("Sending command: %.*s", len, buffer_ptr(&command));
! 739: packet_start(SSH_CMSG_EXEC_CMD);
! 740: packet_put_string(buffer_ptr(&command), buffer_len(&command));
! 741: packet_send();
! 742: packet_write_wait();
! 743: } else {
! 744: debug("Requesting shell.");
! 745: packet_start(SSH_CMSG_EXEC_SHELL);
! 746: packet_send();
! 747: packet_write_wait();
! 748: }
! 749:
! 750: /* Enter the interactive session. */
! 751: exit_status = client_loop(tty_flag, tty_flag ? options.escape_char : -1);
! 752:
! 753: /* Close the connection to the remote host. */
! 754: packet_close();
! 755:
! 756: /* Exit with the status returned by the program on the remote side. */
! 757: exit(exit_status);
1.1 deraadt 758: }
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