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 * Ssh client program. This program can be used to log into a remote machine. 6 * The software supports strong authentication, encryption, and forwarding 7 * of X11, TCP/IP, and authentication connections. 8 * 9 * As far as I am concerned, the code I have written for this software 10 * can be used freely for any purpose. Any derived versions of this 11 * software must be clearly marked as such, and if the derived work is 12 * incompatible with the protocol description in the RFC file, it must be 13 * called by a name other than "ssh" or "Secure Shell". 14 * 15 * Copyright (c) 1999 Niels Provos. All rights reserved. 16 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 17 * 18 * Modified to work with SSL by Niels Provos <provos@citi.umich.edu> 19 * in Canada (German citizen). 20 * 21 * Redistribution and use in source and binary forms, with or without 22 * modification, are permitted provided that the following conditions 23 * are met: 24 * 1. Redistributions of source code must retain the above copyright 25 * notice, this list of conditions and the following disclaimer. 26 * 2. Redistributions in binary form must reproduce the above copyright 27 * notice, this list of conditions and the following disclaimer in the 28 * documentation and/or other materials provided with the distribution. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 31 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 33 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 34 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 35 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 39 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 40 */ 41 42 #include "includes.h" 43 RCSID("$OpenBSD: ssh.c,v 1.190 2003/02/06 09:27:29 markus Exp $"); 44 RCSID("$FreeBSD$"); 45 46 #include <openssl/evp.h> 47 #include <openssl/err.h> 48 49 #include "ssh.h" 50 #include "ssh1.h" 51 #include "ssh2.h" 52 #include "compat.h" 53 #include "cipher.h" 54 #include "xmalloc.h" 55 #include "packet.h" 56 #include "buffer.h" 57 #include "channels.h" 58 #include "key.h" 59 #include "authfd.h" 60 #include "authfile.h" 61 #include "pathnames.h" 62 #include "clientloop.h" 63 #include "log.h" 64 #include "readconf.h" 65 #include "sshconnect.h" 66 #include "tildexpand.h" 67 #include "dispatch.h" 68 #include "misc.h" 69 #include "kex.h" 70 #include "mac.h" 71 #include "sshtty.h" 72 73 #ifdef SMARTCARD 74 #include "scard.h" 75 #endif 76 77 #ifdef HAVE___PROGNAME 78 extern char *__progname; 79 #else 80 char *__progname; 81 #endif 82 83 /* Flag indicating whether IPv4 or IPv6. This can be set on the command line. 84 Default value is AF_UNSPEC means both IPv4 and IPv6. */ 85 #ifdef IPV4_DEFAULT 86 int IPv4or6 = AF_INET; 87 #else 88 int IPv4or6 = AF_UNSPEC; 89 #endif 90 91 /* Flag indicating whether debug mode is on. This can be set on the command line. */ 92 int debug_flag = 0; 93 94 /* Flag indicating whether a tty should be allocated */ 95 int tty_flag = 0; 96 int no_tty_flag = 0; 97 int force_tty_flag = 0; 98 99 /* don't exec a shell */ 100 int no_shell_flag = 0; 101 102 /* 103 * Flag indicating that nothing should be read from stdin. This can be set 104 * on the command line. 105 */ 106 int stdin_null_flag = 0; 107 108 /* 109 * Flag indicating that ssh should fork after authentication. This is useful 110 * so that the passphrase can be entered manually, and then ssh goes to the 111 * background. 112 */ 113 int fork_after_authentication_flag = 0; 114 115 /* 116 * General data structure for command line options and options configurable 117 * in configuration files. See readconf.h. 118 */ 119 Options options; 120 121 /* optional user configfile */ 122 char *config = NULL; 123 124 /* 125 * Name of the host we are connecting to. This is the name given on the 126 * command line, or the HostName specified for the user-supplied name in a 127 * configuration file. 128 */ 129 char *host; 130 131 /* socket address the host resolves to */ 132 struct sockaddr_storage hostaddr; 133 134 /* Private host keys. */ 135 Sensitive sensitive_data; 136 137 /* Original real UID. */ 138 uid_t original_real_uid; 139 uid_t original_effective_uid; 140 141 /* command to be executed */ 142 Buffer command; 143 144 /* Should we execute a command or invoke a subsystem? */ 145 int subsystem_flag = 0; 146 147 /* # of replies received for global requests */ 148 static int client_global_request_id = 0; 149 150 /* pid of proxycommand child process */ 151 pid_t proxy_command_pid = 0; 152 153 /* Prints a help message to the user. This function never returns. */ 154 155 static void 156 usage(void) 157 { 158 fprintf(stderr, "Usage: %s [options] host [command]\n", __progname); 159 fprintf(stderr, "Options:\n"); 160 fprintf(stderr, " -l user Log in using this user name.\n"); 161 fprintf(stderr, " -n Redirect input from " _PATH_DEVNULL ".\n"); 162 fprintf(stderr, " -F config Config file (default: ~/%s).\n", 163 _PATH_SSH_USER_CONFFILE); 164 fprintf(stderr, " -A Enable authentication agent forwarding.\n"); 165 fprintf(stderr, " -a Disable authentication agent forwarding (default).\n"); 166 #ifdef AFS 167 fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n"); 168 #endif /* AFS */ 169 fprintf(stderr, " -X Enable X11 connection forwarding.\n"); 170 fprintf(stderr, " -x Disable X11 connection forwarding (default).\n"); 171 fprintf(stderr, " -i file Identity for public key authentication " 172 "(default: ~/.ssh/identity)\n"); 173 #ifdef SMARTCARD 174 fprintf(stderr, " -I reader Set smartcard reader.\n"); 175 #endif 176 fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n"); 177 fprintf(stderr, " -T Do not allocate a tty.\n"); 178 fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); 179 fprintf(stderr, " Multiple -v increases verbosity.\n"); 180 fprintf(stderr, " -V Display version number only.\n"); 181 fprintf(stderr, " -q Quiet; don't display any warning messages.\n"); 182 fprintf(stderr, " -f Fork into background after authentication.\n"); 183 fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n"); 184 185 fprintf(stderr, " -c cipher Select encryption algorithm\n"); 186 fprintf(stderr, " -m macs Specify MAC algorithms for protocol version 2.\n"); 187 fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n"); 188 fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n"); 189 fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n"); 190 fprintf(stderr, " These cause %s to listen for connections on a port, and\n", __progname); 191 fprintf(stderr, " forward them to the other side by connecting to host:port.\n"); 192 fprintf(stderr, " -D port Enable dynamic application-level port forwarding.\n"); 193 fprintf(stderr, " -C Enable compression.\n"); 194 fprintf(stderr, " -N Do not execute a shell or command.\n"); 195 fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n"); 196 fprintf(stderr, " -1 Force protocol version 1.\n"); 197 fprintf(stderr, " -2 Force protocol version 2.\n"); 198 fprintf(stderr, " -4 Use IPv4 only.\n"); 199 fprintf(stderr, " -6 Use IPv6 only.\n"); 200 fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n"); 201 fprintf(stderr, " -s Invoke command (mandatory) as SSH2 subsystem.\n"); 202 fprintf(stderr, " -b addr Local IP address.\n"); 203 exit(1); 204 } 205 206 static int ssh_session(void); 207 static int ssh_session2(void); 208 static void load_public_identity_files(void); 209 210 /* 211 * Main program for the ssh client. 212 */ 213 int 214 main(int ac, char **av) 215 { 216 int i, opt, exit_status; 217 u_short fwd_port, fwd_host_port; 218 char sfwd_port[6], sfwd_host_port[6]; 219 char *p, *cp, buf[256]; 220 struct stat st; 221 struct passwd *pw; 222 int dummy; 223 extern int optind, optreset; 224 extern char *optarg; 225 226 __progname = get_progname(av[0]); 227 init_rng(); 228 229 /* 230 * Save the original real uid. It will be needed later (uid-swapping 231 * may clobber the real uid). 232 */ 233 original_real_uid = getuid(); 234 original_effective_uid = geteuid(); 235 236 /* 237 * Use uid-swapping to give up root privileges for the duration of 238 * option processing. We will re-instantiate the rights when we are 239 * ready to create the privileged port, and will permanently drop 240 * them when the port has been created (actually, when the connection 241 * has been made, as we may need to create the port several times). 242 */ 243 PRIV_END; 244 245 #ifdef HAVE_SETRLIMIT 246 /* If we are installed setuid root be careful to not drop core. */ 247 if (original_real_uid != original_effective_uid) { 248 struct rlimit rlim; 249 rlim.rlim_cur = rlim.rlim_max = 0; 250 if (setrlimit(RLIMIT_CORE, &rlim) < 0) 251 fatal("setrlimit failed: %.100s", strerror(errno)); 252 } 253 #endif 254 /* Get user data. */ 255 pw = getpwuid(original_real_uid); 256 if (!pw) { 257 log("unknown user %d", original_real_uid); 258 exit(1); 259 } 260 /* Take a copy of the returned structure. */ 261 pw = pwcopy(pw); 262 263 /* 264 * Set our umask to something reasonable, as some files are created 265 * with the default umask. This will make them world-readable but 266 * writable only by the owner, which is ok for all files for which we 267 * don't set the modes explicitly. 268 */ 269 umask(022); 270 271 /* Initialize option structure to indicate that no values have been set. */ 272 initialize_options(&options); 273 274 /* Parse command-line arguments. */ 275 host = NULL; 276 277 again: 278 while ((opt = getopt(ac, av, 279 "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVX")) != -1) { 280 switch (opt) { 281 case '1': 282 options.protocol = SSH_PROTO_1; 283 break; 284 case '2': 285 options.protocol = SSH_PROTO_2; 286 break; 287 case '4': 288 IPv4or6 = AF_INET; 289 break; 290 case '6': 291 IPv4or6 = AF_INET6; 292 break; 293 case 'n': 294 stdin_null_flag = 1; 295 break; 296 case 'f': 297 fork_after_authentication_flag = 1; 298 stdin_null_flag = 1; 299 break; 300 case 'x': 301 options.forward_x11 = 0; 302 break; 303 case 'X': 304 options.forward_x11 = 1; 305 break; 306 case 'g': 307 options.gateway_ports = 1; 308 break; 309 case 'P': /* deprecated */ 310 options.use_privileged_port = 0; 311 break; 312 case 'a': 313 options.forward_agent = 0; 314 break; 315 case 'A': 316 options.forward_agent = 1; 317 break; 318 #ifdef AFS 319 case 'k': 320 options.kerberos_tgt_passing = 0; 321 options.afs_token_passing = 0; 322 break; 323 #endif 324 case 'i': 325 if (stat(optarg, &st) < 0) { 326 fprintf(stderr, "Warning: Identity file %s " 327 "does not exist.\n", optarg); 328 break; 329 } 330 if (options.num_identity_files >= 331 SSH_MAX_IDENTITY_FILES) 332 fatal("Too many identity files specified " 333 "(max %d)", SSH_MAX_IDENTITY_FILES); 334 options.identity_files[options.num_identity_files++] = 335 xstrdup(optarg); 336 break; 337 case 'I': 338 #ifdef SMARTCARD 339 options.smartcard_device = xstrdup(optarg); 340 #else 341 fprintf(stderr, "no support for smartcards.\n"); 342 #endif 343 break; 344 case 't': 345 if (tty_flag) 346 force_tty_flag = 1; 347 tty_flag = 1; 348 break; 349 case 'v': 350 if (0 == debug_flag) { 351 debug_flag = 1; 352 options.log_level = SYSLOG_LEVEL_DEBUG1; 353 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { 354 options.log_level++; 355 break; 356 } else 357 fatal("Too high debugging level."); 358 /* fallthrough */ 359 case 'V': 360 fprintf(stderr, 361 "%s, SSH protocols %d.%d/%d.%d, OpenSSL 0x%8.8lx\n", 362 SSH_VERSION, 363 PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1, 364 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, 365 SSLeay()); 366 if (opt == 'V') 367 exit(0); 368 break; 369 case 'q': 370 options.log_level = SYSLOG_LEVEL_QUIET; 371 break; 372 case 'e': 373 if (optarg[0] == '^' && optarg[2] == 0 && 374 (u_char) optarg[1] >= 64 && 375 (u_char) optarg[1] < 128) 376 options.escape_char = (u_char) optarg[1] & 31; 377 else if (strlen(optarg) == 1) 378 options.escape_char = (u_char) optarg[0]; 379 else if (strcmp(optarg, "none") == 0) 380 options.escape_char = SSH_ESCAPECHAR_NONE; 381 else { 382 fprintf(stderr, "Bad escape character '%s'.\n", 383 optarg); 384 exit(1); 385 } 386 break; 387 case 'c': 388 if (ciphers_valid(optarg)) { 389 /* SSH2 only */ 390 options.ciphers = xstrdup(optarg); 391 options.cipher = SSH_CIPHER_ILLEGAL; 392 } else { 393 /* SSH1 only */ 394 options.cipher = cipher_number(optarg); 395 if (options.cipher == -1) { 396 fprintf(stderr, 397 "Unknown cipher type '%s'\n", 398 optarg); 399 exit(1); 400 } 401 if (options.cipher == SSH_CIPHER_3DES) 402 options.ciphers = "3des-cbc"; 403 else if (options.cipher == SSH_CIPHER_BLOWFISH) 404 options.ciphers = "blowfish-cbc"; 405 else 406 options.ciphers = (char *)-1; 407 } 408 break; 409 case 'm': 410 if (mac_valid(optarg)) 411 options.macs = xstrdup(optarg); 412 else { 413 fprintf(stderr, "Unknown mac type '%s'\n", 414 optarg); 415 exit(1); 416 } 417 break; 418 case 'p': 419 options.port = a2port(optarg); 420 if (options.port == 0) { 421 fprintf(stderr, "Bad port '%s'\n", optarg); 422 exit(1); 423 } 424 break; 425 case 'l': 426 options.user = optarg; 427 break; 428 429 case 'L': 430 case 'R': 431 if (sscanf(optarg, "%5[0-9]:%255[^:]:%5[0-9]", 432 sfwd_port, buf, sfwd_host_port) != 3 && 433 sscanf(optarg, "%5[0-9]/%255[^/]/%5[0-9]", 434 sfwd_port, buf, sfwd_host_port) != 3) { 435 fprintf(stderr, 436 "Bad forwarding specification '%s'\n", 437 optarg); 438 usage(); 439 /* NOTREACHED */ 440 } 441 if ((fwd_port = a2port(sfwd_port)) == 0 || 442 (fwd_host_port = a2port(sfwd_host_port)) == 0) { 443 fprintf(stderr, 444 "Bad forwarding port(s) '%s'\n", optarg); 445 exit(1); 446 } 447 if (opt == 'L') 448 add_local_forward(&options, fwd_port, buf, 449 fwd_host_port); 450 else if (opt == 'R') 451 add_remote_forward(&options, fwd_port, buf, 452 fwd_host_port); 453 break; 454 455 case 'D': 456 fwd_port = a2port(optarg); 457 if (fwd_port == 0) { 458 fprintf(stderr, "Bad dynamic port '%s'\n", 459 optarg); 460 exit(1); 461 } 462 add_local_forward(&options, fwd_port, "socks4", 0); 463 break; 464 465 case 'C': 466 options.compression = 1; 467 break; 468 case 'N': 469 no_shell_flag = 1; 470 no_tty_flag = 1; 471 break; 472 case 'T': 473 no_tty_flag = 1; 474 break; 475 case 'o': 476 dummy = 1; 477 if (process_config_line(&options, host ? host : "", 478 optarg, "command-line", 0, &dummy) != 0) 479 exit(1); 480 break; 481 case 's': 482 subsystem_flag = 1; 483 break; 484 case 'b': 485 options.bind_address = optarg; 486 break; 487 case 'F': 488 config = optarg; 489 break; 490 default: 491 usage(); 492 } 493 } 494 495 ac -= optind; 496 av += optind; 497 498 if (ac > 0 && !host && **av != '-') { 499 if (strrchr(*av, '@')) { 500 p = xstrdup(*av); 501 cp = strrchr(p, '@'); 502 if (cp == NULL || cp == p) 503 usage(); 504 options.user = p; 505 *cp = '\0'; 506 host = ++cp; 507 } else 508 host = *av; 509 if (ac > 1) { 510 optind = optreset = 1; 511 goto again; 512 } 513 ac--, av++; 514 } 515 516 /* Check that we got a host name. */ 517 if (!host) 518 usage(); 519 520 SSLeay_add_all_algorithms(); 521 ERR_load_crypto_strings(); 522 channel_set_af(IPv4or6); 523 524 /* Initialize the command to execute on remote host. */ 525 buffer_init(&command); 526 527 /* 528 * Save the command to execute on the remote host in a buffer. There 529 * is no limit on the length of the command, except by the maximum 530 * packet size. Also sets the tty flag if there is no command. 531 */ 532 if (!ac) { 533 /* No command specified - execute shell on a tty. */ 534 tty_flag = 1; 535 if (subsystem_flag) { 536 fprintf(stderr, 537 "You must specify a subsystem to invoke.\n"); 538 usage(); 539 } 540 } else { 541 /* A command has been specified. Store it into the buffer. */ 542 for (i = 0; i < ac; i++) { 543 if (i) 544 buffer_append(&command, " ", 1); 545 buffer_append(&command, av[i], strlen(av[i])); 546 } 547 } 548 549 /* Cannot fork to background if no command. */ 550 if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag) 551 fatal("Cannot fork into background without a command to execute."); 552 553 /* Allocate a tty by default if no command specified. */ 554 if (buffer_len(&command) == 0) 555 tty_flag = 1; 556 557 /* Force no tty */ 558 if (no_tty_flag) 559 tty_flag = 0; 560 /* Do not allocate a tty if stdin is not a tty. */ 561 if (!isatty(fileno(stdin)) && !force_tty_flag) { 562 if (tty_flag) 563 log("Pseudo-terminal will not be allocated because stdin is not a terminal."); 564 tty_flag = 0; 565 } 566 567 /* 568 * Initialize "log" output. Since we are the client all output 569 * actually goes to stderr. 570 */ 571 log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level, 572 SYSLOG_FACILITY_USER, 1); 573 574 /* 575 * Read per-user configuration file. Ignore the system wide config 576 * file if the user specifies a config file on the command line. 577 */ 578 if (config != NULL) { 579 if (!read_config_file(config, host, &options)) 580 fatal("Can't open user config file %.100s: " 581 "%.100s", config, strerror(errno)); 582 } else { 583 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, 584 _PATH_SSH_USER_CONFFILE); 585 (void)read_config_file(buf, host, &options); 586 587 /* Read systemwide configuration file after use config. */ 588 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options); 589 } 590 591 /* Fill configuration defaults. */ 592 fill_default_options(&options); 593 594 /* reinit */ 595 log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1); 596 597 seed_rng(); 598 599 if (options.user == NULL) 600 options.user = xstrdup(pw->pw_name); 601 602 if (options.hostname != NULL) 603 host = options.hostname; 604 605 /* Find canonic host name. */ 606 if (strchr(host, '.') == 0) { 607 struct addrinfo hints; 608 struct addrinfo *ai = NULL; 609 int errgai; 610 memset(&hints, 0, sizeof(hints)); 611 hints.ai_family = IPv4or6; 612 hints.ai_flags = AI_CANONNAME; 613 hints.ai_socktype = SOCK_STREAM; 614 errgai = getaddrinfo(host, NULL, &hints, &ai); 615 if (errgai == 0) { 616 if (ai->ai_canonname != NULL) 617 host = xstrdup(ai->ai_canonname); 618 freeaddrinfo(ai); 619 } 620 } 621 622 if (options.proxy_command != NULL && 623 strcmp(options.proxy_command, "none") == 0) 624 options.proxy_command = NULL; 625 626 /* Disable rhosts authentication if not running as root. */ 627 #ifdef HAVE_CYGWIN 628 /* Ignore uid if running under Windows */ 629 if (!options.use_privileged_port) { 630 #else 631 if (original_effective_uid != 0 || !options.use_privileged_port) { 632 #endif 633 debug("Rhosts Authentication disabled, " 634 "originating port will not be trusted."); 635 options.rhosts_authentication = 0; 636 } 637 /* Open a connection to the remote host. */ 638 639 if (ssh_connect(host, &hostaddr, options.port, IPv4or6, 640 options.connection_attempts, 641 #ifdef HAVE_CYGWIN 642 options.use_privileged_port, 643 #else 644 original_effective_uid == 0 && options.use_privileged_port, 645 #endif 646 options.proxy_command) != 0) 647 exit(1); 648 649 /* 650 * If we successfully made the connection, load the host private key 651 * in case we will need it later for combined rsa-rhosts 652 * authentication. This must be done before releasing extra 653 * privileges, because the file is only readable by root. 654 * If we cannot access the private keys, load the public keys 655 * instead and try to execute the ssh-keysign helper instead. 656 */ 657 sensitive_data.nkeys = 0; 658 sensitive_data.keys = NULL; 659 sensitive_data.external_keysign = 0; 660 if (options.rhosts_rsa_authentication || 661 options.hostbased_authentication) { 662 sensitive_data.nkeys = 3; 663 sensitive_data.keys = xmalloc(sensitive_data.nkeys * 664 sizeof(Key)); 665 666 PRIV_START; 667 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1, 668 _PATH_HOST_KEY_FILE, "", NULL); 669 sensitive_data.keys[1] = key_load_private_type(KEY_DSA, 670 _PATH_HOST_DSA_KEY_FILE, "", NULL); 671 sensitive_data.keys[2] = key_load_private_type(KEY_RSA, 672 _PATH_HOST_RSA_KEY_FILE, "", NULL); 673 PRIV_END; 674 675 if (options.hostbased_authentication == 1 && 676 sensitive_data.keys[0] == NULL && 677 sensitive_data.keys[1] == NULL && 678 sensitive_data.keys[2] == NULL) { 679 sensitive_data.keys[1] = key_load_public( 680 _PATH_HOST_DSA_KEY_FILE, NULL); 681 sensitive_data.keys[2] = key_load_public( 682 _PATH_HOST_RSA_KEY_FILE, NULL); 683 sensitive_data.external_keysign = 1; 684 } 685 } 686 /* 687 * Get rid of any extra privileges that we may have. We will no 688 * longer need them. Also, extra privileges could make it very hard 689 * to read identity files and other non-world-readable files from the 690 * user's home directory if it happens to be on a NFS volume where 691 * root is mapped to nobody. 692 */ 693 seteuid(original_real_uid); 694 setuid(original_real_uid); 695 696 /* 697 * Now that we are back to our own permissions, create ~/.ssh 698 * directory if it doesn\'t already exist. 699 */ 700 snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR); 701 if (stat(buf, &st) < 0) 702 if (mkdir(buf, 0700) < 0) 703 error("Could not create directory '%.200s'.", buf); 704 705 /* load options.identity_files */ 706 load_public_identity_files(); 707 708 /* Expand ~ in known host file names. */ 709 /* XXX mem-leaks: */ 710 options.system_hostfile = 711 tilde_expand_filename(options.system_hostfile, original_real_uid); 712 options.user_hostfile = 713 tilde_expand_filename(options.user_hostfile, original_real_uid); 714 options.system_hostfile2 = 715 tilde_expand_filename(options.system_hostfile2, original_real_uid); 716 options.user_hostfile2 = 717 tilde_expand_filename(options.user_hostfile2, original_real_uid); 718 719 signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */ 720 721 /* Log into the remote system. This never returns if the login fails. */ 722 ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw); 723 724 /* We no longer need the private host keys. Clear them now. */ 725 if (sensitive_data.nkeys != 0) { 726 for (i = 0; i < sensitive_data.nkeys; i++) { 727 if (sensitive_data.keys[i] != NULL) { 728 /* Destroys contents safely */ 729 debug3("clear hostkey %d", i); 730 key_free(sensitive_data.keys[i]); 731 sensitive_data.keys[i] = NULL; 732 } 733 } 734 xfree(sensitive_data.keys); 735 } 736 for (i = 0; i < options.num_identity_files; i++) { 737 if (options.identity_files[i]) { 738 xfree(options.identity_files[i]); 739 options.identity_files[i] = NULL; 740 } 741 if (options.identity_keys[i]) { 742 key_free(options.identity_keys[i]); 743 options.identity_keys[i] = NULL; 744 } 745 } 746 747 exit_status = compat20 ? ssh_session2() : ssh_session(); 748 packet_close(); 749 750 /* 751 * Send SIGHUP to proxy command if used. We don't wait() in 752 * case it hangs and instead rely on init to reap the child 753 */ 754 if (proxy_command_pid > 1) 755 kill(proxy_command_pid, SIGHUP); 756 757 return exit_status; 758 } 759 760 static void 761 x11_get_proto(char **_proto, char **_data) 762 { 763 char line[512]; 764 static char proto[512], data[512]; 765 FILE *f; 766 int got_data = 0, i; 767 char *display; 768 struct stat st; 769 770 *_proto = proto; 771 *_data = data; 772 proto[0] = data[0] = '\0'; 773 if (!options.xauth_location || 774 (stat(options.xauth_location, &st) == -1)) { 775 debug("No xauth program."); 776 } else { 777 if ((display = getenv("DISPLAY")) == NULL) { 778 debug("x11_get_proto: DISPLAY not set"); 779 return; 780 } 781 /* Try to get Xauthority information for the display. */ 782 if (strncmp(display, "localhost:", 10) == 0) 783 /* 784 * Handle FamilyLocal case where $DISPLAY does 785 * not match an authorization entry. For this we 786 * just try "xauth list unix:displaynum.screennum". 787 * XXX: "localhost" match to determine FamilyLocal 788 * is not perfect. 789 */ 790 snprintf(line, sizeof line, "%s list unix:%s 2>" 791 _PATH_DEVNULL, options.xauth_location, display+10); 792 else 793 snprintf(line, sizeof line, "%s list %.200s 2>" 794 _PATH_DEVNULL, options.xauth_location, display); 795 debug2("x11_get_proto: %s", line); 796 f = popen(line, "r"); 797 if (f && fgets(line, sizeof(line), f) && 798 sscanf(line, "%*s %511s %511s", proto, data) == 2) 799 got_data = 1; 800 if (f) 801 pclose(f); 802 } 803 /* 804 * If we didn't get authentication data, just make up some 805 * data. The forwarding code will check the validity of the 806 * response anyway, and substitute this data. The X11 807 * server, however, will ignore this fake data and use 808 * whatever authentication mechanisms it was using otherwise 809 * for the local connection. 810 */ 811 if (!got_data) { 812 u_int32_t rand = 0; 813 814 log("Warning: No xauth data; using fake authentication data for X11 forwarding."); 815 strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto); 816 for (i = 0; i < 16; i++) { 817 if (i % 4 == 0) 818 rand = arc4random(); 819 snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff); 820 rand >>= 8; 821 } 822 } 823 } 824 825 static void 826 ssh_init_forwarding(void) 827 { 828 int success = 0; 829 int i; 830 831 /* Initiate local TCP/IP port forwardings. */ 832 for (i = 0; i < options.num_local_forwards; i++) { 833 debug("Connections to local port %d forwarded to remote address %.200s:%d", 834 options.local_forwards[i].port, 835 options.local_forwards[i].host, 836 options.local_forwards[i].host_port); 837 success += channel_setup_local_fwd_listener( 838 options.local_forwards[i].port, 839 options.local_forwards[i].host, 840 options.local_forwards[i].host_port, 841 options.gateway_ports); 842 } 843 if (i > 0 && success == 0) 844 error("Could not request local forwarding."); 845 846 /* Initiate remote TCP/IP port forwardings. */ 847 for (i = 0; i < options.num_remote_forwards; i++) { 848 debug("Connections to remote port %d forwarded to local address %.200s:%d", 849 options.remote_forwards[i].port, 850 options.remote_forwards[i].host, 851 options.remote_forwards[i].host_port); 852 channel_request_remote_forwarding( 853 options.remote_forwards[i].port, 854 options.remote_forwards[i].host, 855 options.remote_forwards[i].host_port); 856 } 857 } 858 859 static void 860 check_agent_present(void) 861 { 862 if (options.forward_agent) { 863 /* Clear agent forwarding if we don\'t have an agent. */ 864 if (!ssh_agent_present()) 865 options.forward_agent = 0; 866 } 867 } 868 869 static int 870 ssh_session(void) 871 { 872 int type; 873 int interactive = 0; 874 int have_tty = 0; 875 struct winsize ws; 876 char *cp; 877 878 /* Enable compression if requested. */ 879 if (options.compression) { 880 debug("Requesting compression at level %d.", options.compression_level); 881 882 if (options.compression_level < 1 || options.compression_level > 9) 883 fatal("Compression level must be from 1 (fast) to 9 (slow, best)."); 884 885 /* Send the request. */ 886 packet_start(SSH_CMSG_REQUEST_COMPRESSION); 887 packet_put_int(options.compression_level); 888 packet_send(); 889 packet_write_wait(); 890 type = packet_read(); 891 if (type == SSH_SMSG_SUCCESS) 892 packet_start_compression(options.compression_level); 893 else if (type == SSH_SMSG_FAILURE) 894 log("Warning: Remote host refused compression."); 895 else 896 packet_disconnect("Protocol error waiting for compression response."); 897 } 898 /* Allocate a pseudo tty if appropriate. */ 899 if (tty_flag) { 900 debug("Requesting pty."); 901 902 /* Start the packet. */ 903 packet_start(SSH_CMSG_REQUEST_PTY); 904 905 /* Store TERM in the packet. There is no limit on the 906 length of the string. */ 907 cp = getenv("TERM"); 908 if (!cp) 909 cp = ""; 910 packet_put_cstring(cp); 911 912 /* Store window size in the packet. */ 913 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) 914 memset(&ws, 0, sizeof(ws)); 915 packet_put_int(ws.ws_row); 916 packet_put_int(ws.ws_col); 917 packet_put_int(ws.ws_xpixel); 918 packet_put_int(ws.ws_ypixel); 919 920 /* Store tty modes in the packet. */ 921 tty_make_modes(fileno(stdin), NULL); 922 923 /* Send the packet, and wait for it to leave. */ 924 packet_send(); 925 packet_write_wait(); 926 927 /* Read response from the server. */ 928 type = packet_read(); 929 if (type == SSH_SMSG_SUCCESS) { 930 interactive = 1; 931 have_tty = 1; 932 } else if (type == SSH_SMSG_FAILURE) 933 log("Warning: Remote host failed or refused to allocate a pseudo tty."); 934 else 935 packet_disconnect("Protocol error waiting for pty request response."); 936 } 937 /* Request X11 forwarding if enabled and DISPLAY is set. */ 938 if (options.forward_x11 && getenv("DISPLAY") != NULL) { 939 char *proto, *data; 940 /* Get reasonable local authentication information. */ 941 x11_get_proto(&proto, &data); 942 /* Request forwarding with authentication spoofing. */ 943 debug("Requesting X11 forwarding with authentication spoofing."); 944 x11_request_forwarding_with_spoofing(0, proto, data); 945 946 /* Read response from the server. */ 947 type = packet_read(); 948 if (type == SSH_SMSG_SUCCESS) { 949 interactive = 1; 950 } else if (type == SSH_SMSG_FAILURE) { 951 log("Warning: Remote host denied X11 forwarding."); 952 } else { 953 packet_disconnect("Protocol error waiting for X11 forwarding"); 954 } 955 } 956 /* Tell the packet module whether this is an interactive session. */ 957 packet_set_interactive(interactive); 958 959 /* Request authentication agent forwarding if appropriate. */ 960 check_agent_present(); 961 962 if (options.forward_agent) { 963 debug("Requesting authentication agent forwarding."); 964 auth_request_forwarding(); 965 966 /* Read response from the server. */ 967 type = packet_read(); 968 packet_check_eom(); 969 if (type != SSH_SMSG_SUCCESS) 970 log("Warning: Remote host denied authentication agent forwarding."); 971 } 972 973 /* Initiate port forwardings. */ 974 ssh_init_forwarding(); 975 976 /* If requested, let ssh continue in the background. */ 977 if (fork_after_authentication_flag) 978 if (daemon(1, 1) < 0) 979 fatal("daemon() failed: %.200s", strerror(errno)); 980 981 /* 982 * If a command was specified on the command line, execute the 983 * command now. Otherwise request the server to start a shell. 984 */ 985 if (buffer_len(&command) > 0) { 986 int len = buffer_len(&command); 987 if (len > 900) 988 len = 900; 989 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command)); 990 packet_start(SSH_CMSG_EXEC_CMD); 991 packet_put_string(buffer_ptr(&command), buffer_len(&command)); 992 packet_send(); 993 packet_write_wait(); 994 } else { 995 debug("Requesting shell."); 996 packet_start(SSH_CMSG_EXEC_SHELL); 997 packet_send(); 998 packet_write_wait(); 999 } 1000 1001 /* Enter the interactive session. */ 1002 return client_loop(have_tty, tty_flag ? 1003 options.escape_char : SSH_ESCAPECHAR_NONE, 0); 1004 } 1005 1006 static void 1007 client_subsystem_reply(int type, u_int32_t seq, void *ctxt) 1008 { 1009 int id, len; 1010 1011 id = packet_get_int(); 1012 len = buffer_len(&command); 1013 if (len > 900) 1014 len = 900; 1015 packet_check_eom(); 1016 if (type == SSH2_MSG_CHANNEL_FAILURE) 1017 fatal("Request for subsystem '%.*s' failed on channel %d", 1018 len, (u_char *)buffer_ptr(&command), id); 1019 } 1020 1021 void 1022 client_global_request_reply(int type, u_int32_t seq, void *ctxt) 1023 { 1024 int i; 1025 1026 i = client_global_request_id++; 1027 if (i >= options.num_remote_forwards) { 1028 debug("client_global_request_reply: too many replies %d > %d", 1029 i, options.num_remote_forwards); 1030 return; 1031 } 1032 debug("remote forward %s for: listen %d, connect %s:%d", 1033 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 1034 options.remote_forwards[i].port, 1035 options.remote_forwards[i].host, 1036 options.remote_forwards[i].host_port); 1037 if (type == SSH2_MSG_REQUEST_FAILURE) 1038 log("Warning: remote port forwarding failed for listen port %d", 1039 options.remote_forwards[i].port); 1040 } 1041 1042 /* request pty/x11/agent/tcpfwd/shell for channel */ 1043 static void 1044 ssh_session2_setup(int id, void *arg) 1045 { 1046 int len; 1047 int interactive = 0; 1048 struct termios tio; 1049 1050 debug2("ssh_session2_setup: id %d", id); 1051 1052 if (tty_flag) { 1053 struct winsize ws; 1054 char *cp; 1055 cp = getenv("TERM"); 1056 if (!cp) 1057 cp = ""; 1058 /* Store window size in the packet. */ 1059 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) 1060 memset(&ws, 0, sizeof(ws)); 1061 1062 channel_request_start(id, "pty-req", 0); 1063 packet_put_cstring(cp); 1064 packet_put_int(ws.ws_col); 1065 packet_put_int(ws.ws_row); 1066 packet_put_int(ws.ws_xpixel); 1067 packet_put_int(ws.ws_ypixel); 1068 tio = get_saved_tio(); 1069 tty_make_modes(/*ignored*/ 0, &tio); 1070 packet_send(); 1071 interactive = 1; 1072 /* XXX wait for reply */ 1073 } 1074 if (options.forward_x11 && 1075 getenv("DISPLAY") != NULL) { 1076 char *proto, *data; 1077 /* Get reasonable local authentication information. */ 1078 x11_get_proto(&proto, &data); 1079 /* Request forwarding with authentication spoofing. */ 1080 debug("Requesting X11 forwarding with authentication spoofing."); 1081 x11_request_forwarding_with_spoofing(id, proto, data); 1082 interactive = 1; 1083 /* XXX wait for reply */ 1084 } 1085 1086 check_agent_present(); 1087 if (options.forward_agent) { 1088 debug("Requesting authentication agent forwarding."); 1089 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1090 packet_send(); 1091 } 1092 1093 len = buffer_len(&command); 1094 if (len > 0) { 1095 if (len > 900) 1096 len = 900; 1097 if (subsystem_flag) { 1098 debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command)); 1099 channel_request_start(id, "subsystem", /*want reply*/ 1); 1100 /* register callback for reply */ 1101 /* XXX we assume that client_loop has already been called */ 1102 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply); 1103 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply); 1104 } else { 1105 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command)); 1106 channel_request_start(id, "exec", 0); 1107 } 1108 packet_put_string(buffer_ptr(&command), buffer_len(&command)); 1109 packet_send(); 1110 } else { 1111 channel_request_start(id, "shell", 0); 1112 packet_send(); 1113 } 1114 1115 packet_set_interactive(interactive); 1116 } 1117 1118 /* open new channel for a session */ 1119 static int 1120 ssh_session2_open(void) 1121 { 1122 Channel *c; 1123 int window, packetmax, in, out, err; 1124 1125 if (stdin_null_flag) { 1126 in = open(_PATH_DEVNULL, O_RDONLY); 1127 } else { 1128 in = dup(STDIN_FILENO); 1129 } 1130 out = dup(STDOUT_FILENO); 1131 err = dup(STDERR_FILENO); 1132 1133 if (in < 0 || out < 0 || err < 0) 1134 fatal("dup() in/out/err failed"); 1135 1136 /* enable nonblocking unless tty */ 1137 if (!isatty(in)) 1138 set_nonblock(in); 1139 if (!isatty(out)) 1140 set_nonblock(out); 1141 if (!isatty(err)) 1142 set_nonblock(err); 1143 1144 window = CHAN_SES_WINDOW_DEFAULT; 1145 packetmax = CHAN_SES_PACKET_DEFAULT; 1146 if (tty_flag) { 1147 window >>= 1; 1148 packetmax >>= 1; 1149 } 1150 c = channel_new( 1151 "session", SSH_CHANNEL_OPENING, in, out, err, 1152 window, packetmax, CHAN_EXTENDED_WRITE, 1153 xstrdup("client-session"), /*nonblock*/0); 1154 1155 debug3("ssh_session2_open: channel_new: %d", c->self); 1156 1157 channel_send_open(c->self); 1158 if (!no_shell_flag) 1159 channel_register_confirm(c->self, ssh_session2_setup); 1160 1161 return c->self; 1162 } 1163 1164 static int 1165 ssh_session2(void) 1166 { 1167 int id = -1; 1168 1169 /* XXX should be pre-session */ 1170 ssh_init_forwarding(); 1171 1172 if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN)) 1173 id = ssh_session2_open(); 1174 1175 /* If requested, let ssh continue in the background. */ 1176 if (fork_after_authentication_flag) 1177 if (daemon(1, 1) < 0) 1178 fatal("daemon() failed: %.200s", strerror(errno)); 1179 1180 return client_loop(tty_flag, tty_flag ? 1181 options.escape_char : SSH_ESCAPECHAR_NONE, id); 1182 } 1183 1184 static void 1185 load_public_identity_files(void) 1186 { 1187 char *filename; 1188 int i = 0; 1189 Key *public; 1190 #ifdef SMARTCARD 1191 Key **keys; 1192 1193 if (options.smartcard_device != NULL && 1194 options.num_identity_files < SSH_MAX_IDENTITY_FILES && 1195 (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) { 1196 int count = 0; 1197 for (i = 0; keys[i] != NULL; i++) { 1198 count++; 1199 memmove(&options.identity_files[1], &options.identity_files[0], 1200 sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1)); 1201 memmove(&options.identity_keys[1], &options.identity_keys[0], 1202 sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1)); 1203 options.num_identity_files++; 1204 options.identity_keys[0] = keys[i]; 1205 options.identity_files[0] = xstrdup("smartcard key");; 1206 } 1207 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES) 1208 options.num_identity_files = SSH_MAX_IDENTITY_FILES; 1209 i = count; 1210 xfree(keys); 1211 } 1212 #endif /* SMARTCARD */ 1213 for (; i < options.num_identity_files; i++) { 1214 filename = tilde_expand_filename(options.identity_files[i], 1215 original_real_uid); 1216 public = key_load_public(filename, NULL); 1217 debug("identity file %s type %d", filename, 1218 public ? public->type : -1); 1219 xfree(options.identity_files[i]); 1220 options.identity_files[i] = filename; 1221 options.identity_keys[i] = public; 1222 } 1223 } 1224