1 /* 2 * Author: Tatu Ylonen <ylo@cs.hut.fi> 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * Created: Sat Mar 18 16:36:11 1995 ylo 6 * Ssh client program. This program can be used to log into a remote machine. 7 * The software supports strong authentication, encryption, and forwarding 8 * of X11, TCP/IP, and authentication connections. 9 * 10 * Modified to work with SSL by Niels Provos <provos@citi.umich.edu> in Canada. 11 * 12 * $FreeBSD$ 13 */ 14 15 #include "includes.h" 16 RCSID("$Id: ssh.c,v 1.54 2000/05/30 17:32:06 markus Exp $"); 17 18 #include <openssl/evp.h> 19 #include <openssl/dsa.h> 20 #include <openssl/rsa.h> 21 22 #include "xmalloc.h" 23 #include "ssh.h" 24 #include "packet.h" 25 #include "buffer.h" 26 #include "authfd.h" 27 #include "readconf.h" 28 #include "uidswap.h" 29 30 #include "ssh2.h" 31 #include "compat.h" 32 #include "channels.h" 33 #include "key.h" 34 #include "authfile.h" 35 36 extern char *__progname; 37 38 /* Flag indicating whether IPv4 or IPv6. This can be set on the command line. 39 Default value is AF_UNSPEC means both IPv4 and IPv6. */ 40 int IPv4or6 = AF_UNSPEC; 41 42 /* Flag indicating whether debug mode is on. This can be set on the command line. */ 43 int debug_flag = 0; 44 45 /* Flag indicating whether a tty should be allocated */ 46 int tty_flag = 0; 47 48 /* don't exec a shell */ 49 int no_shell_flag = 0; 50 int no_tty_flag = 0; 51 52 /* 53 * Flag indicating that nothing should be read from stdin. This can be set 54 * on the command line. 55 */ 56 int stdin_null_flag = 0; 57 58 /* 59 * Flag indicating that ssh should fork after authentication. This is useful 60 * so that the pasphrase can be entered manually, and then ssh goes to the 61 * background. 62 */ 63 int fork_after_authentication_flag = 0; 64 65 /* 66 * General data structure for command line options and options configurable 67 * in configuration files. See readconf.h. 68 */ 69 Options options; 70 71 /* 72 * Name of the host we are connecting to. This is the name given on the 73 * command line, or the HostName specified for the user-supplied name in a 74 * configuration file. 75 */ 76 char *host; 77 78 /* socket address the host resolves to */ 79 struct sockaddr_storage hostaddr; 80 81 /* 82 * Flag to indicate that we have received a window change signal which has 83 * not yet been processed. This will cause a message indicating the new 84 * window size to be sent to the server a little later. This is volatile 85 * because this is updated in a signal handler. 86 */ 87 volatile int received_window_change_signal = 0; 88 89 /* Value of argv[0] (set in the main program). */ 90 char *av0; 91 92 /* Flag indicating whether we have a valid host private key loaded. */ 93 int host_private_key_loaded = 0; 94 95 /* Host private key. */ 96 RSA *host_private_key = NULL; 97 98 /* Original real UID. */ 99 uid_t original_real_uid; 100 101 /* command to be executed */ 102 Buffer command; 103 104 /* Prints a help message to the user. This function never returns. */ 105 106 void 107 usage() 108 { 109 fprintf(stderr, "Usage: %s [options] host [command]\n", av0); 110 fprintf(stderr, "Options:\n"); 111 fprintf(stderr, " -l user Log in using this user name.\n"); 112 fprintf(stderr, " -n Redirect input from /dev/null.\n"); 113 fprintf(stderr, " -A Enable authentication agent forwarding.\n"); 114 fprintf(stderr, " -a Disable authentication agent forwarding.\n"); 115 #ifdef AFS 116 fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n"); 117 #endif /* AFS */ 118 fprintf(stderr, " -X Enable X11 connection forwarding.\n"); 119 fprintf(stderr, " -x Disable X11 connection forwarding.\n"); 120 fprintf(stderr, " -X Enable X11 connection forwarding.\n"); 121 fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n"); 122 fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n"); 123 fprintf(stderr, " -T Do not allocate a tty.\n"); 124 fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); 125 fprintf(stderr, " -V Display version number only.\n"); 126 fprintf(stderr, " -P Don't allocate a privileged port.\n"); 127 fprintf(stderr, " -q Quiet; don't display any warning messages.\n"); 128 fprintf(stderr, " -f Fork into background after authentication.\n"); 129 fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n"); 130 131 fprintf(stderr, " -c cipher Select encryption algorithm: " 132 "``3des'', " 133 "``blowfish''\n"); 134 fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n"); 135 fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n"); 136 fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n"); 137 fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0); 138 fprintf(stderr, " forward them to the other side by connecting to host:port.\n"); 139 fprintf(stderr, " -C Enable compression.\n"); 140 fprintf(stderr, " -N Do not execute a shell or command.\n"); 141 fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n"); 142 fprintf(stderr, " -4 Use IPv4 only.\n"); 143 fprintf(stderr, " -6 Use IPv6 only.\n"); 144 fprintf(stderr, " -2 Force protocol version 2.\n"); 145 fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n"); 146 exit(1); 147 } 148 149 /* 150 * Connects to the given host using rsh (or prints an error message and exits 151 * if rsh is not available). This function never returns. 152 */ 153 void 154 rsh_connect(char *host, char *user, Buffer * command) 155 { 156 char *args[10]; 157 int i; 158 159 log("Using rsh. WARNING: Connection will not be encrypted."); 160 /* Build argument list for rsh. */ 161 i = 0; 162 #ifndef _PATH_RSH 163 #define _PATH_RSH "/usr/bin/rsh" 164 #endif 165 args[i++] = _PATH_RSH; 166 /* host may have to come after user on some systems */ 167 args[i++] = host; 168 if (user) { 169 args[i++] = "-l"; 170 args[i++] = user; 171 } 172 if (buffer_len(command) > 0) { 173 buffer_append(command, "\0", 1); 174 args[i++] = buffer_ptr(command); 175 } 176 args[i++] = NULL; 177 if (debug_flag) { 178 for (i = 0; args[i]; i++) { 179 if (i != 0) 180 fprintf(stderr, " "); 181 fprintf(stderr, "%s", args[i]); 182 } 183 fprintf(stderr, "\n"); 184 } 185 execv(_PATH_RSH, args); 186 perror(_PATH_RSH); 187 exit(1); 188 } 189 190 int ssh_session(void); 191 int ssh_session2(void); 192 193 /* 194 * Main program for the ssh client. 195 */ 196 int 197 main(int ac, char **av) 198 { 199 int i, opt, optind, exit_status, ok; 200 u_short fwd_port, fwd_host_port; 201 char *optarg, *cp, buf[256]; 202 struct stat st; 203 struct passwd *pw, pwcopy; 204 int dummy; 205 uid_t original_effective_uid; 206 207 /* 208 * Save the original real uid. It will be needed later (uid-swapping 209 * may clobber the real uid). 210 */ 211 original_real_uid = getuid(); 212 original_effective_uid = geteuid(); 213 214 /* If we are installed setuid root be careful to not drop core. */ 215 if (original_real_uid != original_effective_uid) { 216 struct rlimit rlim; 217 rlim.rlim_cur = rlim.rlim_max = 0; 218 if (setrlimit(RLIMIT_CORE, &rlim) < 0) 219 fatal("setrlimit failed: %.100s", strerror(errno)); 220 } 221 /* 222 * Use uid-swapping to give up root privileges for the duration of 223 * option processing. We will re-instantiate the rights when we are 224 * ready to create the privileged port, and will permanently drop 225 * them when the port has been created (actually, when the connection 226 * has been made, as we may need to create the port several times). 227 */ 228 temporarily_use_uid(original_real_uid); 229 230 /* 231 * Set our umask to something reasonable, as some files are created 232 * with the default umask. This will make them world-readable but 233 * writable only by the owner, which is ok for all files for which we 234 * don't set the modes explicitly. 235 */ 236 umask(022); 237 238 /* Save our own name. */ 239 av0 = av[0]; 240 241 /* Initialize option structure to indicate that no values have been set. */ 242 initialize_options(&options); 243 244 /* Parse command-line arguments. */ 245 host = NULL; 246 247 /* If program name is not one of the standard names, use it as host name. */ 248 if (strchr(av0, '/')) 249 cp = strrchr(av0, '/') + 1; 250 else 251 cp = av0; 252 if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 && 253 strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0) 254 host = cp; 255 256 for (optind = 1; optind < ac; optind++) { 257 if (av[optind][0] != '-') { 258 if (host) 259 break; 260 if ((cp = strchr(av[optind], '@'))) { 261 if(cp == av[optind]) 262 usage(); 263 options.user = av[optind]; 264 *cp = '\0'; 265 host = ++cp; 266 } else 267 host = av[optind]; 268 continue; 269 } 270 opt = av[optind][1]; 271 if (!opt) 272 usage(); 273 if (strchr("eilcpLRo", opt)) { /* options with arguments */ 274 optarg = av[optind] + 2; 275 if (strcmp(optarg, "") == 0) { 276 if (optind >= ac - 1) 277 usage(); 278 optarg = av[++optind]; 279 } 280 } else { 281 if (av[optind][2]) 282 usage(); 283 optarg = NULL; 284 } 285 switch (opt) { 286 case '2': 287 options.protocol = SSH_PROTO_2; 288 break; 289 case '4': 290 IPv4or6 = AF_INET; 291 break; 292 case '6': 293 IPv4or6 = AF_INET6; 294 break; 295 case 'n': 296 stdin_null_flag = 1; 297 break; 298 case 'f': 299 fork_after_authentication_flag = 1; 300 stdin_null_flag = 1; 301 break; 302 case 'x': 303 options.forward_x11 = 0; 304 break; 305 case 'X': 306 options.forward_x11 = 1; 307 break; 308 case 'g': 309 options.gateway_ports = 1; 310 break; 311 case 'P': 312 options.use_privileged_port = 0; 313 break; 314 case 'a': 315 options.forward_agent = 0; 316 break; 317 case 'A': 318 options.forward_agent = 1; 319 break; 320 #ifdef AFS 321 case 'k': 322 options.krb4_tgt_passing = 0; 323 options.krb5_tgt_passing = 0; 324 options.afs_token_passing = 0; 325 break; 326 #endif 327 case 'i': 328 if (stat(optarg, &st) < 0) { 329 fprintf(stderr, "Warning: Identity file %s does not exist.\n", 330 optarg); 331 break; 332 } 333 if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES) 334 fatal("Too many identity files specified (max %d)", 335 SSH_MAX_IDENTITY_FILES); 336 options.identity_files[options.num_identity_files++] = 337 xstrdup(optarg); 338 break; 339 case 't': 340 tty_flag = 1; 341 break; 342 case 'v': 343 case 'V': 344 fprintf(stderr, "SSH Version %s, protocol versions %d.%d/%d.%d.\n", 345 SSH_VERSION, 346 PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1, 347 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2); 348 fprintf(stderr, "Compiled with SSL (0x%8.8lx).\n", SSLeay()); 349 if (opt == 'V') 350 exit(0); 351 debug_flag = 1; 352 options.log_level = SYSLOG_LEVEL_DEBUG; 353 break; 354 case 'q': 355 options.log_level = SYSLOG_LEVEL_QUIET; 356 break; 357 case 'e': 358 if (optarg[0] == '^' && optarg[2] == 0 && 359 (unsigned char) optarg[1] >= 64 && (unsigned char) optarg[1] < 128) 360 options.escape_char = (unsigned char) optarg[1] & 31; 361 else if (strlen(optarg) == 1) 362 options.escape_char = (unsigned char) optarg[0]; 363 else if (strcmp(optarg, "none") == 0) 364 options.escape_char = -2; 365 else { 366 fprintf(stderr, "Bad escape character '%s'.\n", optarg); 367 exit(1); 368 } 369 break; 370 case 'c': 371 if (ciphers_valid(optarg)) { 372 /* SSH2 only */ 373 options.ciphers = xstrdup(optarg); 374 options.cipher = SSH_CIPHER_ILLEGAL; 375 } else { 376 /* SSH1 only */ 377 options.cipher = cipher_number(optarg); 378 if (options.cipher == -1) { 379 fprintf(stderr, "Unknown cipher type '%s'\n", optarg); 380 exit(1); 381 } 382 } 383 break; 384 case 'p': 385 options.port = atoi(optarg); 386 break; 387 case 'l': 388 options.user = optarg; 389 break; 390 case 'R': 391 if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf, 392 &fwd_host_port) != 3 && 393 sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, 394 &fwd_host_port) != 3) { 395 fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); 396 usage(); 397 /* NOTREACHED */ 398 } 399 add_remote_forward(&options, fwd_port, buf, fwd_host_port); 400 break; 401 case 'L': 402 if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf, 403 &fwd_host_port) != 3 && 404 sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf, 405 &fwd_host_port) != 3) { 406 fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); 407 usage(); 408 /* NOTREACHED */ 409 } 410 add_local_forward(&options, fwd_port, buf, fwd_host_port); 411 break; 412 case 'C': 413 options.compression = 1; 414 break; 415 case 'N': 416 no_shell_flag = 1; 417 no_tty_flag = 1; 418 break; 419 case 'T': 420 no_tty_flag = 1; 421 break; 422 case 'o': 423 dummy = 1; 424 if (process_config_line(&options, host ? host : "", optarg, 425 "command-line", 0, &dummy) != 0) 426 exit(1); 427 break; 428 default: 429 usage(); 430 } 431 } 432 433 /* Check that we got a host name. */ 434 if (!host) 435 usage(); 436 437 SSLeay_add_all_algorithms(); 438 439 /* Initialize the command to execute on remote host. */ 440 buffer_init(&command); 441 442 /* 443 * Save the command to execute on the remote host in a buffer. There 444 * is no limit on the length of the command, except by the maximum 445 * packet size. Also sets the tty flag if there is no command. 446 */ 447 if (optind == ac) { 448 /* No command specified - execute shell on a tty. */ 449 tty_flag = 1; 450 } else { 451 /* A command has been specified. Store it into the 452 buffer. */ 453 for (i = optind; i < ac; i++) { 454 if (i > optind) 455 buffer_append(&command, " ", 1); 456 buffer_append(&command, av[i], strlen(av[i])); 457 } 458 } 459 460 /* Cannot fork to background if no command. */ 461 if (fork_after_authentication_flag && buffer_len(&command) == 0) 462 fatal("Cannot fork into background without a command to execute."); 463 464 /* Allocate a tty by default if no command specified. */ 465 if (buffer_len(&command) == 0) 466 tty_flag = 1; 467 468 /* Do not allocate a tty if stdin is not a tty. */ 469 if (!isatty(fileno(stdin))) { 470 if (tty_flag) 471 fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n"); 472 tty_flag = 0; 473 } 474 /* force */ 475 if (no_tty_flag) 476 tty_flag = 0; 477 478 /* Get user data. */ 479 pw = getpwuid(original_real_uid); 480 if (!pw) { 481 fprintf(stderr, "You don't exist, go away!\n"); 482 exit(1); 483 } 484 /* Take a copy of the returned structure. */ 485 memset(&pwcopy, 0, sizeof(pwcopy)); 486 pwcopy.pw_name = xstrdup(pw->pw_name); 487 pwcopy.pw_passwd = xstrdup(pw->pw_passwd); 488 pwcopy.pw_uid = pw->pw_uid; 489 pwcopy.pw_gid = pw->pw_gid; 490 pwcopy.pw_dir = xstrdup(pw->pw_dir); 491 pwcopy.pw_shell = xstrdup(pw->pw_shell); 492 pw = &pwcopy; 493 494 /* Initialize "log" output. Since we are the client all output 495 actually goes to the terminal. */ 496 log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); 497 498 /* Read per-user configuration file. */ 499 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE); 500 read_config_file(buf, host, &options); 501 502 /* Read systemwide configuration file. */ 503 read_config_file(HOST_CONFIG_FILE, host, &options); 504 505 /* Fill configuration defaults. */ 506 fill_default_options(&options); 507 508 /* reinit */ 509 log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); 510 511 /* check if RSA support exists */ 512 if ((options.protocol & SSH_PROTO_1) && 513 rsa_alive() == 0) { 514 log("%s: no RSA support in libssl and libcrypto. See ssl(8).", 515 __progname); 516 log("Disabling protocol version 1"); 517 options.protocol &= ~ (SSH_PROTO_1|SSH_PROTO_1_PREFERRED); 518 } 519 if (! options.protocol & (SSH_PROTO_1|SSH_PROTO_2)) { 520 fprintf(stderr, "%s: No protocol version available.\n", 521 __progname); 522 exit(1); 523 } 524 525 if (options.user == NULL) 526 options.user = xstrdup(pw->pw_name); 527 528 if (options.hostname != NULL) 529 host = options.hostname; 530 531 /* Find canonic host name. */ 532 if (strchr(host, '.') == 0) { 533 struct addrinfo hints; 534 struct addrinfo *ai = NULL; 535 int errgai; 536 memset(&hints, 0, sizeof(hints)); 537 hints.ai_family = IPv4or6; 538 hints.ai_flags = AI_CANONNAME; 539 hints.ai_socktype = SOCK_STREAM; 540 errgai = getaddrinfo(host, NULL, &hints, &ai); 541 if (errgai == 0) { 542 if (ai->ai_canonname != NULL) 543 host = xstrdup(ai->ai_canonname); 544 freeaddrinfo(ai); 545 } 546 } 547 /* Disable rhosts authentication if not running as root. */ 548 if (original_effective_uid != 0 || !options.use_privileged_port) { 549 options.rhosts_authentication = 0; 550 options.rhosts_rsa_authentication = 0; 551 } 552 /* 553 * If using rsh has been selected, exec it now (without trying 554 * anything else). Note that we must release privileges first. 555 */ 556 if (options.use_rsh) { 557 /* 558 * Restore our superuser privileges. This must be done 559 * before permanently setting the uid. 560 */ 561 restore_uid(); 562 563 /* Switch to the original uid permanently. */ 564 permanently_set_uid(original_real_uid); 565 566 /* Execute rsh. */ 567 rsh_connect(host, options.user, &command); 568 fatal("rsh_connect returned"); 569 } 570 /* Restore our superuser privileges. */ 571 restore_uid(); 572 573 /* 574 * Open a connection to the remote host. This needs root privileges 575 * if rhosts_{rsa_}authentication is enabled. 576 */ 577 578 ok = ssh_connect(host, &hostaddr, options.port, 579 options.connection_attempts, 580 !options.rhosts_authentication && 581 !options.rhosts_rsa_authentication, 582 original_real_uid, 583 options.proxy_command); 584 585 /* 586 * If we successfully made the connection, load the host private key 587 * in case we will need it later for combined rsa-rhosts 588 * authentication. This must be done before releasing extra 589 * privileges, because the file is only readable by root. 590 */ 591 if (ok && (options.protocol & SSH_PROTO_1)) { 592 Key k; 593 host_private_key = RSA_new(); 594 k.type = KEY_RSA; 595 k.rsa = host_private_key; 596 if (load_private_key(HOST_KEY_FILE, "", &k, NULL)) 597 host_private_key_loaded = 1; 598 } 599 /* 600 * Get rid of any extra privileges that we may have. We will no 601 * longer need them. Also, extra privileges could make it very hard 602 * to read identity files and other non-world-readable files from the 603 * user's home directory if it happens to be on a NFS volume where 604 * root is mapped to nobody. 605 */ 606 607 /* 608 * Note that some legacy systems need to postpone the following call 609 * to permanently_set_uid() until the private hostkey is destroyed 610 * with RSA_free(). Otherwise the calling user could ptrace() the 611 * process, read the private hostkey and impersonate the host. 612 * OpenBSD does not allow ptracing of setuid processes. 613 */ 614 permanently_set_uid(original_real_uid); 615 616 /* 617 * Now that we are back to our own permissions, create ~/.ssh 618 * directory if it doesn\'t already exist. 619 */ 620 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR); 621 if (stat(buf, &st) < 0) 622 if (mkdir(buf, 0755) < 0) 623 error("Could not create directory '%.200s'.", buf); 624 625 /* Check if the connection failed, and try "rsh" if appropriate. */ 626 if (!ok) { 627 if (options.port != 0) 628 log("Secure connection to %.100s on port %hu refused%.100s.", 629 host, options.port, 630 options.fallback_to_rsh ? "; reverting to insecure method" : ""); 631 else 632 log("Secure connection to %.100s refused%.100s.", host, 633 options.fallback_to_rsh ? "; reverting to insecure method" : ""); 634 635 if (options.fallback_to_rsh) { 636 rsh_connect(host, options.user, &command); 637 fatal("rsh_connect returned"); 638 } 639 exit(1); 640 } 641 /* Expand ~ in options.identity_files. */ 642 /* XXX mem-leaks */ 643 for (i = 0; i < options.num_identity_files; i++) 644 options.identity_files[i] = 645 tilde_expand_filename(options.identity_files[i], original_real_uid); 646 for (i = 0; i < options.num_identity_files2; i++) 647 options.identity_files2[i] = 648 tilde_expand_filename(options.identity_files2[i], original_real_uid); 649 /* Expand ~ in known host file names. */ 650 options.system_hostfile = tilde_expand_filename(options.system_hostfile, 651 original_real_uid); 652 options.user_hostfile = tilde_expand_filename(options.user_hostfile, 653 original_real_uid); 654 options.system_hostfile2 = tilde_expand_filename(options.system_hostfile2, 655 original_real_uid); 656 options.user_hostfile2 = tilde_expand_filename(options.user_hostfile2, 657 original_real_uid); 658 659 /* Log into the remote system. This never returns if the login fails. */ 660 ssh_login(host_private_key_loaded, host_private_key, 661 host, (struct sockaddr *)&hostaddr, original_real_uid); 662 663 /* We no longer need the host private key. Clear it now. */ 664 if (host_private_key_loaded) 665 RSA_free(host_private_key); /* Destroys contents safely */ 666 667 exit_status = compat20 ? ssh_session2() : ssh_session(); 668 packet_close(); 669 return exit_status; 670 } 671 672 void 673 x11_get_proto(char *proto, int proto_len, char *data, int data_len) 674 { 675 char line[512]; 676 FILE *f; 677 int got_data = 0, i; 678 679 #ifdef XAUTH_PATH 680 /* Try to get Xauthority information for the display. */ 681 snprintf(line, sizeof line, "%.100s list %.200s 2>/dev/null", 682 XAUTH_PATH, getenv("DISPLAY")); 683 f = popen(line, "r"); 684 if (f && fgets(line, sizeof(line), f) && 685 sscanf(line, "%*s %s %s", proto, data) == 2) 686 got_data = 1; 687 if (f) 688 pclose(f); 689 #endif /* XAUTH_PATH */ 690 /* 691 * If we didn't get authentication data, just make up some 692 * data. The forwarding code will check the validity of the 693 * response anyway, and substitute this data. The X11 694 * server, however, will ignore this fake data and use 695 * whatever authentication mechanisms it was using otherwise 696 * for the local connection. 697 */ 698 if (!got_data) { 699 u_int32_t rand = 0; 700 701 strlcpy(proto, "MIT-MAGIC-COOKIE-1", proto_len); 702 for (i = 0; i < 16; i++) { 703 if (i % 4 == 0) 704 rand = arc4random(); 705 snprintf(data + 2 * i, data_len - 2 * i, "%02x", rand & 0xff); 706 rand >>= 8; 707 } 708 } 709 } 710 711 int 712 ssh_session(void) 713 { 714 int type; 715 int i; 716 int plen; 717 int interactive = 0; 718 int have_tty = 0; 719 struct winsize ws; 720 int authfd; 721 char *cp; 722 723 /* Enable compression if requested. */ 724 if (options.compression) { 725 debug("Requesting compression at level %d.", options.compression_level); 726 727 if (options.compression_level < 1 || options.compression_level > 9) 728 fatal("Compression level must be from 1 (fast) to 9 (slow, best)."); 729 730 /* Send the request. */ 731 packet_start(SSH_CMSG_REQUEST_COMPRESSION); 732 packet_put_int(options.compression_level); 733 packet_send(); 734 packet_write_wait(); 735 type = packet_read(&plen); 736 if (type == SSH_SMSG_SUCCESS) 737 packet_start_compression(options.compression_level); 738 else if (type == SSH_SMSG_FAILURE) 739 log("Warning: Remote host refused compression."); 740 else 741 packet_disconnect("Protocol error waiting for compression response."); 742 } 743 /* Allocate a pseudo tty if appropriate. */ 744 if (tty_flag) { 745 debug("Requesting pty."); 746 747 /* Start the packet. */ 748 packet_start(SSH_CMSG_REQUEST_PTY); 749 750 /* Store TERM in the packet. There is no limit on the 751 length of the string. */ 752 cp = getenv("TERM"); 753 if (!cp) 754 cp = ""; 755 packet_put_string(cp, strlen(cp)); 756 757 /* Store window size in the packet. */ 758 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) 759 memset(&ws, 0, sizeof(ws)); 760 packet_put_int(ws.ws_row); 761 packet_put_int(ws.ws_col); 762 packet_put_int(ws.ws_xpixel); 763 packet_put_int(ws.ws_ypixel); 764 765 /* Store tty modes in the packet. */ 766 tty_make_modes(fileno(stdin)); 767 768 /* Send the packet, and wait for it to leave. */ 769 packet_send(); 770 packet_write_wait(); 771 772 /* Read response from the server. */ 773 type = packet_read(&plen); 774 if (type == SSH_SMSG_SUCCESS) { 775 interactive = 1; 776 have_tty = 1; 777 } else if (type == SSH_SMSG_FAILURE) 778 log("Warning: Remote host failed or refused to allocate a pseudo tty."); 779 else 780 packet_disconnect("Protocol error waiting for pty request response."); 781 } 782 /* Request X11 forwarding if enabled and DISPLAY is set. */ 783 if (options.forward_x11 && getenv("DISPLAY") != NULL) { 784 char proto[512], data[512]; 785 /* Get reasonable local authentication information. */ 786 x11_get_proto(proto, sizeof proto, data, sizeof data); 787 /* Request forwarding with authentication spoofing. */ 788 debug("Requesting X11 forwarding with authentication spoofing."); 789 x11_request_forwarding_with_spoofing(0, proto, data); 790 791 /* Read response from the server. */ 792 type = packet_read(&plen); 793 if (type == SSH_SMSG_SUCCESS) { 794 interactive = 1; 795 } else if (type == SSH_SMSG_FAILURE) { 796 log("Warning: Remote host denied X11 forwarding."); 797 } else { 798 packet_disconnect("Protocol error waiting for X11 forwarding"); 799 } 800 } 801 /* Tell the packet module whether this is an interactive session. */ 802 packet_set_interactive(interactive, options.keepalives); 803 804 /* Clear agent forwarding if we don\'t have an agent. */ 805 authfd = ssh_get_authentication_socket(); 806 if (authfd < 0) 807 options.forward_agent = 0; 808 else 809 ssh_close_authentication_socket(authfd); 810 811 /* Request authentication agent forwarding if appropriate. */ 812 if (options.forward_agent) { 813 debug("Requesting authentication agent forwarding."); 814 auth_request_forwarding(); 815 816 /* Read response from the server. */ 817 type = packet_read(&plen); 818 packet_integrity_check(plen, 0, type); 819 if (type != SSH_SMSG_SUCCESS) 820 log("Warning: Remote host denied authentication agent forwarding."); 821 } 822 /* Initiate local TCP/IP port forwardings. */ 823 for (i = 0; i < options.num_local_forwards; i++) { 824 debug("Connections to local port %d forwarded to remote address %.200s:%d", 825 options.local_forwards[i].port, 826 options.local_forwards[i].host, 827 options.local_forwards[i].host_port); 828 channel_request_local_forwarding(options.local_forwards[i].port, 829 options.local_forwards[i].host, 830 options.local_forwards[i].host_port, 831 options.gateway_ports); 832 } 833 834 /* Initiate remote TCP/IP port forwardings. */ 835 for (i = 0; i < options.num_remote_forwards; i++) { 836 debug("Connections to remote port %d forwarded to local address %.200s:%d", 837 options.remote_forwards[i].port, 838 options.remote_forwards[i].host, 839 options.remote_forwards[i].host_port); 840 channel_request_remote_forwarding(options.remote_forwards[i].port, 841 options.remote_forwards[i].host, 842 options.remote_forwards[i].host_port); 843 } 844 845 /* If requested, let ssh continue in the background. */ 846 if (fork_after_authentication_flag) 847 if (daemon(1, 1) < 0) 848 fatal("daemon() failed: %.200s", strerror(errno)); 849 850 /* 851 * If a command was specified on the command line, execute the 852 * command now. Otherwise request the server to start a shell. 853 */ 854 if (buffer_len(&command) > 0) { 855 int len = buffer_len(&command); 856 if (len > 900) 857 len = 900; 858 debug("Sending command: %.*s", len, buffer_ptr(&command)); 859 packet_start(SSH_CMSG_EXEC_CMD); 860 packet_put_string(buffer_ptr(&command), buffer_len(&command)); 861 packet_send(); 862 packet_write_wait(); 863 } else { 864 debug("Requesting shell."); 865 packet_start(SSH_CMSG_EXEC_SHELL); 866 packet_send(); 867 packet_write_wait(); 868 } 869 870 /* Enter the interactive session. */ 871 return client_loop(have_tty, tty_flag ? options.escape_char : -1); 872 } 873 874 void 875 init_local_fwd(void) 876 { 877 int i; 878 /* Initiate local TCP/IP port forwardings. */ 879 for (i = 0; i < options.num_local_forwards; i++) { 880 debug("Connections to local port %d forwarded to remote address %.200s:%d", 881 options.local_forwards[i].port, 882 options.local_forwards[i].host, 883 options.local_forwards[i].host_port); 884 channel_request_local_forwarding(options.local_forwards[i].port, 885 options.local_forwards[i].host, 886 options.local_forwards[i].host_port, 887 options.gateway_ports); 888 } 889 } 890 891 extern void client_set_session_ident(int id); 892 893 void 894 client_init(int id, void *arg) 895 { 896 int len; 897 debug("client_init id %d arg %d", id, (int)arg); 898 899 if (no_shell_flag) 900 goto done; 901 902 if (tty_flag) { 903 struct winsize ws; 904 char *cp; 905 cp = getenv("TERM"); 906 if (!cp) 907 cp = ""; 908 /* Store window size in the packet. */ 909 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) 910 memset(&ws, 0, sizeof(ws)); 911 912 channel_request_start(id, "pty-req", 0); 913 packet_put_cstring(cp); 914 packet_put_int(ws.ws_col); 915 packet_put_int(ws.ws_row); 916 packet_put_int(ws.ws_xpixel); 917 packet_put_int(ws.ws_ypixel); 918 packet_put_cstring(""); /* XXX: encode terminal modes */ 919 packet_send(); 920 /* XXX wait for reply */ 921 } 922 if (options.forward_x11 && 923 getenv("DISPLAY") != NULL) { 924 char proto[512], data[512]; 925 /* Get reasonable local authentication information. */ 926 x11_get_proto(proto, sizeof proto, data, sizeof data); 927 /* Request forwarding with authentication spoofing. */ 928 debug("Requesting X11 forwarding with authentication spoofing."); 929 x11_request_forwarding_with_spoofing(id, proto, data); 930 /* XXX wait for reply */ 931 } 932 933 len = buffer_len(&command); 934 if (len > 0) { 935 if (len > 900) 936 len = 900; 937 debug("Sending command: %.*s", len, buffer_ptr(&command)); 938 channel_request_start(id, "exec", 0); 939 packet_put_string(buffer_ptr(&command), len); 940 packet_send(); 941 } else { 942 channel_request(id, "shell", 0); 943 } 944 /* channel_callback(id, SSH2_MSG_OPEN_CONFIGMATION, client_init, 0); */ 945 done: 946 /* register different callback, etc. XXX */ 947 client_set_session_ident(id); 948 } 949 950 int 951 ssh_session2(void) 952 { 953 int window, packetmax, id; 954 int in = dup(STDIN_FILENO); 955 int out = dup(STDOUT_FILENO); 956 int err = dup(STDERR_FILENO); 957 958 if (in < 0 || out < 0 || err < 0) 959 fatal("dump in/out/err failed"); 960 961 /* should be pre-session */ 962 init_local_fwd(); 963 964 window = 32*1024; 965 if (tty_flag) { 966 packetmax = window/8; 967 } else { 968 window *= 2; 969 packetmax = window/2; 970 } 971 972 id = channel_new( 973 "session", SSH_CHANNEL_OPENING, in, out, err, 974 window, packetmax, CHAN_EXTENDED_WRITE, xstrdup("client-session")); 975 976 977 channel_open(id); 978 channel_register_callback(id, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, client_init, (void *)0); 979 980 return client_loop(tty_flag, tty_flag ? options.escape_char : -1); 981 } 982