1 /* $OpenBSD: ssh.c,v 1.325 2009/03/17 21:37:00 markus Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 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 * As far as I am concerned, the code I have written for this software 11 * can be used freely for any purpose. Any derived versions of this 12 * software must be clearly marked as such, and if the derived work is 13 * incompatible with the protocol description in the RFC file, it must be 14 * called by a name other than "ssh" or "Secure Shell". 15 * 16 * Copyright (c) 1999 Niels Provos. All rights reserved. 17 * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl. All rights reserved. 18 * 19 * Modified to work with SSL by Niels Provos <provos@citi.umich.edu> 20 * in Canada (German citizen). 21 * 22 * Redistribution and use in source and binary forms, with or without 23 * modification, are permitted provided that the following conditions 24 * are met: 25 * 1. Redistributions of source code must retain the above copyright 26 * notice, this list of conditions and the following disclaimer. 27 * 2. Redistributions in binary form must reproduce the above copyright 28 * notice, this list of conditions and the following disclaimer in the 29 * documentation and/or other materials provided with the distribution. 30 * 31 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 32 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 33 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 34 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 35 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 37 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 38 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 39 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 40 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 41 */ 42 43 #include <sys/types.h> 44 #include <sys/ioctl.h> 45 #include <sys/queue.h> 46 #include <sys/resource.h> 47 #include <sys/socket.h> 48 #include <sys/stat.h> 49 #include <sys/types.h> 50 #include <sys/time.h> 51 52 #include <ctype.h> 53 #include <errno.h> 54 #include <fcntl.h> 55 #include <netdb.h> 56 #include <paths.h> 57 #include <pwd.h> 58 #include <signal.h> 59 #include <stddef.h> 60 #include <stdio.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <unistd.h> 64 65 #include <openssl/evp.h> 66 #include <openssl/err.h> 67 68 #include "xmalloc.h" 69 #include "ssh.h" 70 #include "ssh1.h" 71 #include "ssh2.h" 72 #include "compat.h" 73 #include "cipher.h" 74 #include "packet.h" 75 #include "buffer.h" 76 #include "channels.h" 77 #include "key.h" 78 #include "authfd.h" 79 #include "authfile.h" 80 #include "pathnames.h" 81 #include "dispatch.h" 82 #include "clientloop.h" 83 #include "log.h" 84 #include "readconf.h" 85 #include "sshconnect.h" 86 #include "misc.h" 87 #include "kex.h" 88 #include "mac.h" 89 #include "sshpty.h" 90 #include "match.h" 91 #include "msg.h" 92 #include "uidswap.h" 93 #include "version.h" 94 95 #ifdef SMARTCARD 96 #include "scard.h" 97 #endif 98 99 extern char *__progname; 100 101 /* Flag indicating whether debug mode is on. May be set on the command line. */ 102 int debug_flag = 0; 103 104 /* Flag indicating whether a tty should be allocated */ 105 int tty_flag = 0; 106 int no_tty_flag = 0; 107 int force_tty_flag = 0; 108 109 /* don't exec a shell */ 110 int no_shell_flag = 0; 111 112 /* 113 * Flag indicating that nothing should be read from stdin. This can be set 114 * on the command line. 115 */ 116 int stdin_null_flag = 0; 117 118 /* 119 * Flag indicating that ssh should fork after authentication. This is useful 120 * so that the passphrase can be entered manually, and then ssh goes to the 121 * background. 122 */ 123 int fork_after_authentication_flag = 0; 124 125 /* 126 * General data structure for command line options and options configurable 127 * in configuration files. See readconf.h. 128 */ 129 Options options; 130 131 /* optional user configfile */ 132 char *config = NULL; 133 134 /* 135 * Name of the host we are connecting to. This is the name given on the 136 * command line, or the HostName specified for the user-supplied name in a 137 * configuration file. 138 */ 139 char *host; 140 141 /* socket address the host resolves to */ 142 struct sockaddr_storage hostaddr; 143 144 /* Private host keys. */ 145 Sensitive sensitive_data; 146 147 /* Original real UID. */ 148 uid_t original_real_uid; 149 uid_t original_effective_uid; 150 151 /* command to be executed */ 152 Buffer command; 153 154 /* Should we execute a command or invoke a subsystem? */ 155 int subsystem_flag = 0; 156 157 /* # of replies received for global requests */ 158 static int remote_forward_confirms_received = 0; 159 160 /* pid of proxycommand child process */ 161 pid_t proxy_command_pid = 0; 162 163 /* mux.c */ 164 extern int muxserver_sock; 165 extern u_int muxclient_command; 166 167 168 /* Prints a help message to the user. This function never returns. */ 169 170 static void 171 usage(void) 172 { 173 fprintf(stderr, 174 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n" 175 " [-D [bind_address:]port] [-e escape_char] [-F configfile]\n" 176 " [-i identity_file] [-L [bind_address:]port:host:hostport]\n" 177 " [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n" 178 " [-R [bind_address:]port:host:hostport] [-S ctl_path]\n" 179 " [-w local_tun[:remote_tun]] [user@]hostname [command]\n" 180 ); 181 exit(255); 182 } 183 184 static int ssh_session(void); 185 static int ssh_session2(void); 186 static void load_public_identity_files(void); 187 188 /* from muxclient.c */ 189 void muxclient(const char *); 190 void muxserver_listen(void); 191 192 /* 193 * Main program for the ssh client. 194 */ 195 int 196 main(int ac, char **av) 197 { 198 int i, opt, exit_status, use_syslog; 199 char *p, *cp, *line, *argv0, buf[256]; 200 struct stat st; 201 struct passwd *pw; 202 int dummy, timeout_ms; 203 extern int optind, optreset; 204 extern char *optarg; 205 struct servent *sp; 206 Forward fwd; 207 208 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 209 sanitise_stdfd(); 210 211 /* 212 * Save the original real uid. It will be needed later (uid-swapping 213 * may clobber the real uid). 214 */ 215 original_real_uid = getuid(); 216 original_effective_uid = geteuid(); 217 218 /* 219 * Use uid-swapping to give up root privileges for the duration of 220 * option processing. We will re-instantiate the rights when we are 221 * ready to create the privileged port, and will permanently drop 222 * them when the port has been created (actually, when the connection 223 * has been made, as we may need to create the port several times). 224 */ 225 PRIV_END; 226 227 /* If we are installed setuid root be careful to not drop core. */ 228 if (original_real_uid != original_effective_uid) { 229 struct rlimit rlim; 230 rlim.rlim_cur = rlim.rlim_max = 0; 231 if (setrlimit(RLIMIT_CORE, &rlim) < 0) 232 fatal("setrlimit failed: %.100s", strerror(errno)); 233 } 234 /* Get user data. */ 235 pw = getpwuid(original_real_uid); 236 if (!pw) { 237 logit("You don't exist, go away!"); 238 exit(255); 239 } 240 /* Take a copy of the returned structure. */ 241 pw = pwcopy(pw); 242 243 /* 244 * Set our umask to something reasonable, as some files are created 245 * with the default umask. This will make them world-readable but 246 * writable only by the owner, which is ok for all files for which we 247 * don't set the modes explicitly. 248 */ 249 umask(022); 250 251 /* 252 * Initialize option structure to indicate that no values have been 253 * set. 254 */ 255 initialize_options(&options); 256 257 /* Parse command-line arguments. */ 258 host = NULL; 259 use_syslog = 0; 260 argv0 = av[0]; 261 262 again: 263 while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx" 264 "ACD:F:I:KL:MNO:PR:S:TVw:XYy")) != -1) { 265 switch (opt) { 266 case '1': 267 options.protocol = SSH_PROTO_1; 268 break; 269 case '2': 270 options.protocol = SSH_PROTO_2; 271 break; 272 case '4': 273 options.address_family = AF_INET; 274 break; 275 case '6': 276 options.address_family = AF_INET6; 277 break; 278 case 'n': 279 stdin_null_flag = 1; 280 break; 281 case 'f': 282 fork_after_authentication_flag = 1; 283 stdin_null_flag = 1; 284 break; 285 case 'x': 286 options.forward_x11 = 0; 287 break; 288 case 'X': 289 options.forward_x11 = 1; 290 break; 291 case 'y': 292 use_syslog = 1; 293 break; 294 case 'Y': 295 options.forward_x11 = 1; 296 options.forward_x11_trusted = 1; 297 break; 298 case 'g': 299 options.gateway_ports = 1; 300 break; 301 case 'O': 302 if (strcmp(optarg, "check") == 0) 303 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK; 304 else if (strcmp(optarg, "exit") == 0) 305 muxclient_command = SSHMUX_COMMAND_TERMINATE; 306 else 307 fatal("Invalid multiplex command."); 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 case 'k': 319 options.gss_deleg_creds = 0; 320 break; 321 case 'K': 322 options.gss_authentication = 1; 323 options.gss_deleg_creds = 1; 324 break; 325 case 'i': 326 if (stat(optarg, &st) < 0) { 327 fprintf(stderr, "Warning: Identity file %s " 328 "not accessible: %s.\n", optarg, 329 strerror(errno)); 330 break; 331 } 332 if (options.num_identity_files >= 333 SSH_MAX_IDENTITY_FILES) 334 fatal("Too many identity files specified " 335 "(max %d)", SSH_MAX_IDENTITY_FILES); 336 options.identity_files[options.num_identity_files++] = 337 xstrdup(optarg); 338 break; 339 case 'I': 340 #ifdef SMARTCARD 341 options.smartcard_device = xstrdup(optarg); 342 #else 343 fprintf(stderr, "no support for smartcards.\n"); 344 #endif 345 break; 346 case 't': 347 if (tty_flag) 348 force_tty_flag = 1; 349 tty_flag = 1; 350 break; 351 case 'v': 352 if (debug_flag == 0) { 353 debug_flag = 1; 354 options.log_level = SYSLOG_LEVEL_DEBUG1; 355 } else { 356 if (options.log_level < SYSLOG_LEVEL_DEBUG3) 357 options.log_level++; 358 break; 359 } 360 /* FALLTHROUGH */ 361 case 'V': 362 fprintf(stderr, "%s, %s\n", 363 SSH_VERSION, SSLeay_version(SSLEAY_VERSION)); 364 if (opt == 'V') 365 exit(0); 366 break; 367 case 'w': 368 if (options.tun_open == -1) 369 options.tun_open = SSH_TUNMODE_DEFAULT; 370 options.tun_local = a2tun(optarg, &options.tun_remote); 371 if (options.tun_local == SSH_TUNID_ERR) { 372 fprintf(stderr, 373 "Bad tun device '%s'\n", optarg); 374 exit(255); 375 } 376 break; 377 case 'q': 378 options.log_level = SYSLOG_LEVEL_QUIET; 379 break; 380 case 'e': 381 if (optarg[0] == '^' && optarg[2] == 0 && 382 (u_char) optarg[1] >= 64 && 383 (u_char) optarg[1] < 128) 384 options.escape_char = (u_char) optarg[1] & 31; 385 else if (strlen(optarg) == 1) 386 options.escape_char = (u_char) optarg[0]; 387 else if (strcmp(optarg, "none") == 0) 388 options.escape_char = SSH_ESCAPECHAR_NONE; 389 else { 390 fprintf(stderr, "Bad escape character '%s'.\n", 391 optarg); 392 exit(255); 393 } 394 break; 395 case 'c': 396 if (ciphers_valid(optarg)) { 397 /* SSH2 only */ 398 options.ciphers = xstrdup(optarg); 399 options.cipher = SSH_CIPHER_INVALID; 400 } else { 401 /* SSH1 only */ 402 options.cipher = cipher_number(optarg); 403 if (options.cipher == -1) { 404 fprintf(stderr, 405 "Unknown cipher type '%s'\n", 406 optarg); 407 exit(255); 408 } 409 if (options.cipher == SSH_CIPHER_3DES) 410 options.ciphers = "3des-cbc"; 411 else if (options.cipher == SSH_CIPHER_BLOWFISH) 412 options.ciphers = "blowfish-cbc"; 413 else 414 options.ciphers = (char *)-1; 415 } 416 break; 417 case 'm': 418 if (mac_valid(optarg)) 419 options.macs = xstrdup(optarg); 420 else { 421 fprintf(stderr, "Unknown mac type '%s'\n", 422 optarg); 423 exit(255); 424 } 425 break; 426 case 'M': 427 if (options.control_master == SSHCTL_MASTER_YES) 428 options.control_master = SSHCTL_MASTER_ASK; 429 else 430 options.control_master = SSHCTL_MASTER_YES; 431 break; 432 case 'p': 433 options.port = a2port(optarg); 434 if (options.port <= 0) { 435 fprintf(stderr, "Bad port '%s'\n", optarg); 436 exit(255); 437 } 438 break; 439 case 'l': 440 options.user = optarg; 441 break; 442 443 case 'L': 444 if (parse_forward(&fwd, optarg, 0, 0)) 445 add_local_forward(&options, &fwd); 446 else { 447 fprintf(stderr, 448 "Bad local forwarding specification '%s'\n", 449 optarg); 450 exit(255); 451 } 452 break; 453 454 case 'R': 455 if (parse_forward(&fwd, optarg, 0, 1)) { 456 add_remote_forward(&options, &fwd); 457 } else { 458 fprintf(stderr, 459 "Bad remote forwarding specification " 460 "'%s'\n", optarg); 461 exit(255); 462 } 463 break; 464 465 case 'D': 466 if (parse_forward(&fwd, optarg, 1, 0)) { 467 add_local_forward(&options, &fwd); 468 } else { 469 fprintf(stderr, 470 "Bad dynamic forwarding specification " 471 "'%s'\n", optarg); 472 exit(255); 473 } 474 break; 475 476 case 'C': 477 options.compression = 1; 478 break; 479 case 'N': 480 no_shell_flag = 1; 481 no_tty_flag = 1; 482 break; 483 case 'T': 484 no_tty_flag = 1; 485 break; 486 case 'o': 487 dummy = 1; 488 line = xstrdup(optarg); 489 if (process_config_line(&options, host ? host : "", 490 line, "command-line", 0, &dummy) != 0) 491 exit(255); 492 xfree(line); 493 break; 494 case 's': 495 subsystem_flag = 1; 496 break; 497 case 'S': 498 if (options.control_path != NULL) 499 free(options.control_path); 500 options.control_path = xstrdup(optarg); 501 break; 502 case 'b': 503 options.bind_address = optarg; 504 break; 505 case 'F': 506 config = optarg; 507 break; 508 default: 509 usage(); 510 } 511 } 512 513 ac -= optind; 514 av += optind; 515 516 if (ac > 0 && !host && **av != '-') { 517 if (strrchr(*av, '@')) { 518 p = xstrdup(*av); 519 cp = strrchr(p, '@'); 520 if (cp == NULL || cp == p) 521 usage(); 522 options.user = p; 523 *cp = '\0'; 524 host = ++cp; 525 } else 526 host = *av; 527 if (ac > 1) { 528 optind = optreset = 1; 529 goto again; 530 } 531 ac--, av++; 532 } 533 534 /* Check that we got a host name. */ 535 if (!host) 536 usage(); 537 538 SSLeay_add_all_algorithms(); 539 ERR_load_crypto_strings(); 540 541 /* Initialize the command to execute on remote host. */ 542 buffer_init(&command); 543 544 /* 545 * Save the command to execute on the remote host in a buffer. There 546 * is no limit on the length of the command, except by the maximum 547 * packet size. Also sets the tty flag if there is no command. 548 */ 549 if (!ac) { 550 /* No command specified - execute shell on a tty. */ 551 tty_flag = 1; 552 if (subsystem_flag) { 553 fprintf(stderr, 554 "You must specify a subsystem to invoke.\n"); 555 usage(); 556 } 557 } else { 558 /* A command has been specified. Store it into the buffer. */ 559 for (i = 0; i < ac; i++) { 560 if (i) 561 buffer_append(&command, " ", 1); 562 buffer_append(&command, av[i], strlen(av[i])); 563 } 564 } 565 566 /* Cannot fork to background if no command. */ 567 if (fork_after_authentication_flag && buffer_len(&command) == 0 && 568 !no_shell_flag) 569 fatal("Cannot fork into background without a command " 570 "to execute."); 571 572 /* Allocate a tty by default if no command specified. */ 573 if (buffer_len(&command) == 0) 574 tty_flag = 1; 575 576 /* Force no tty */ 577 if (no_tty_flag) 578 tty_flag = 0; 579 /* Do not allocate a tty if stdin is not a tty. */ 580 if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) { 581 if (tty_flag) 582 logit("Pseudo-terminal will not be allocated because " 583 "stdin is not a terminal."); 584 tty_flag = 0; 585 } 586 587 /* 588 * Initialize "log" output. Since we are the client all output 589 * actually goes to stderr. 590 */ 591 log_init(argv0, 592 options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level, 593 SYSLOG_FACILITY_USER, !use_syslog); 594 595 /* 596 * Read per-user configuration file. Ignore the system wide config 597 * file if the user specifies a config file on the command line. 598 */ 599 if (config != NULL) { 600 if (!read_config_file(config, host, &options, 0)) 601 fatal("Can't open user config file %.100s: " 602 "%.100s", config, strerror(errno)); 603 } else { 604 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, 605 _PATH_SSH_USER_CONFFILE); 606 (void)read_config_file(buf, host, &options, 1); 607 608 /* Read systemwide configuration file after use config. */ 609 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, 610 &options, 0); 611 } 612 613 /* Fill configuration defaults. */ 614 fill_default_options(&options); 615 616 channel_set_af(options.address_family); 617 618 /* reinit */ 619 log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog); 620 621 if (options.user == NULL) 622 options.user = xstrdup(pw->pw_name); 623 624 /* Get default port if port has not been set. */ 625 if (options.port == 0) { 626 sp = getservbyname(SSH_SERVICE_NAME, "tcp"); 627 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT; 628 } 629 630 if (options.local_command != NULL) { 631 char thishost[NI_MAXHOST]; 632 633 if (gethostname(thishost, sizeof(thishost)) == -1) 634 fatal("gethostname: %s", strerror(errno)); 635 snprintf(buf, sizeof(buf), "%d", options.port); 636 debug3("expanding LocalCommand: %s", options.local_command); 637 cp = options.local_command; 638 options.local_command = percent_expand(cp, "d", pw->pw_dir, 639 "h", options.hostname? options.hostname : host, 640 "l", thishost, "n", host, "r", options.user, "p", buf, 641 "u", pw->pw_name, (char *)NULL); 642 debug3("expanded LocalCommand: %s", options.local_command); 643 xfree(cp); 644 } 645 646 if (options.hostname != NULL) 647 host = options.hostname; 648 649 /* force lowercase for hostkey matching */ 650 if (options.host_key_alias != NULL) { 651 for (p = options.host_key_alias; *p; p++) 652 if (isupper(*p)) 653 *p = (char)tolower(*p); 654 } 655 656 if (options.proxy_command != NULL && 657 strcmp(options.proxy_command, "none") == 0) { 658 xfree(options.proxy_command); 659 options.proxy_command = NULL; 660 } 661 if (options.control_path != NULL && 662 strcmp(options.control_path, "none") == 0) { 663 xfree(options.control_path); 664 options.control_path = NULL; 665 } 666 667 if (options.control_path != NULL) { 668 char thishost[NI_MAXHOST]; 669 670 if (gethostname(thishost, sizeof(thishost)) == -1) 671 fatal("gethostname: %s", strerror(errno)); 672 snprintf(buf, sizeof(buf), "%d", options.port); 673 cp = tilde_expand_filename(options.control_path, 674 original_real_uid); 675 xfree(options.control_path); 676 options.control_path = percent_expand(cp, "p", buf, "h", host, 677 "r", options.user, "l", thishost, (char *)NULL); 678 xfree(cp); 679 } 680 if (muxclient_command != 0 && options.control_path == NULL) 681 fatal("No ControlPath specified for \"-O\" command"); 682 if (options.control_path != NULL) 683 muxclient(options.control_path); 684 685 timeout_ms = options.connection_timeout * 1000; 686 687 /* Open a connection to the remote host. */ 688 if (ssh_connect(host, &hostaddr, options.port, 689 options.address_family, options.connection_attempts, &timeout_ms, 690 options.tcp_keep_alive, 691 original_effective_uid == 0 && options.use_privileged_port, 692 options.proxy_command) != 0) 693 exit(255); 694 695 if (timeout_ms > 0) 696 debug3("timeout: %d ms remain after connect", timeout_ms); 697 698 /* 699 * If we successfully made the connection, load the host private key 700 * in case we will need it later for combined rsa-rhosts 701 * authentication. This must be done before releasing extra 702 * privileges, because the file is only readable by root. 703 * If we cannot access the private keys, load the public keys 704 * instead and try to execute the ssh-keysign helper instead. 705 */ 706 sensitive_data.nkeys = 0; 707 sensitive_data.keys = NULL; 708 sensitive_data.external_keysign = 0; 709 if (options.rhosts_rsa_authentication || 710 options.hostbased_authentication) { 711 sensitive_data.nkeys = 3; 712 sensitive_data.keys = xcalloc(sensitive_data.nkeys, 713 sizeof(Key)); 714 715 PRIV_START; 716 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1, 717 _PATH_HOST_KEY_FILE, "", NULL, NULL); 718 sensitive_data.keys[1] = key_load_private_type(KEY_DSA, 719 _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL); 720 sensitive_data.keys[2] = key_load_private_type(KEY_RSA, 721 _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL); 722 PRIV_END; 723 724 if (options.hostbased_authentication == 1 && 725 sensitive_data.keys[0] == NULL && 726 sensitive_data.keys[1] == NULL && 727 sensitive_data.keys[2] == NULL) { 728 sensitive_data.keys[1] = key_load_public( 729 _PATH_HOST_DSA_KEY_FILE, NULL); 730 sensitive_data.keys[2] = key_load_public( 731 _PATH_HOST_RSA_KEY_FILE, NULL); 732 sensitive_data.external_keysign = 1; 733 } 734 } 735 /* 736 * Get rid of any extra privileges that we may have. We will no 737 * longer need them. Also, extra privileges could make it very hard 738 * to read identity files and other non-world-readable files from the 739 * user's home directory if it happens to be on a NFS volume where 740 * root is mapped to nobody. 741 */ 742 if (original_effective_uid == 0) { 743 PRIV_START; 744 permanently_set_uid(pw); 745 } 746 747 /* 748 * Now that we are back to our own permissions, create ~/.ssh 749 * directory if it doesn't already exist. 750 */ 751 snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, 752 strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR); 753 if (stat(buf, &st) < 0) 754 if (mkdir(buf, 0700) < 0) 755 error("Could not create directory '%.200s'.", buf); 756 757 /* load options.identity_files */ 758 load_public_identity_files(); 759 760 /* Expand ~ in known host file names. */ 761 /* XXX mem-leaks: */ 762 options.system_hostfile = 763 tilde_expand_filename(options.system_hostfile, original_real_uid); 764 options.user_hostfile = 765 tilde_expand_filename(options.user_hostfile, original_real_uid); 766 options.system_hostfile2 = 767 tilde_expand_filename(options.system_hostfile2, original_real_uid); 768 options.user_hostfile2 = 769 tilde_expand_filename(options.user_hostfile2, original_real_uid); 770 771 signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */ 772 773 /* Log into the remote system. Never returns if the login fails. */ 774 ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, 775 pw, timeout_ms); 776 777 /* We no longer need the private host keys. Clear them now. */ 778 if (sensitive_data.nkeys != 0) { 779 for (i = 0; i < sensitive_data.nkeys; i++) { 780 if (sensitive_data.keys[i] != NULL) { 781 /* Destroys contents safely */ 782 debug3("clear hostkey %d", i); 783 key_free(sensitive_data.keys[i]); 784 sensitive_data.keys[i] = NULL; 785 } 786 } 787 xfree(sensitive_data.keys); 788 } 789 for (i = 0; i < options.num_identity_files; i++) { 790 if (options.identity_files[i]) { 791 xfree(options.identity_files[i]); 792 options.identity_files[i] = NULL; 793 } 794 if (options.identity_keys[i]) { 795 key_free(options.identity_keys[i]); 796 options.identity_keys[i] = NULL; 797 } 798 } 799 800 exit_status = compat20 ? ssh_session2() : ssh_session(); 801 packet_close(); 802 803 if (options.control_path != NULL && muxserver_sock != -1) 804 unlink(options.control_path); 805 806 /* 807 * Send SIGHUP to proxy command if used. We don't wait() in 808 * case it hangs and instead rely on init to reap the child 809 */ 810 if (proxy_command_pid > 1) 811 kill(proxy_command_pid, SIGHUP); 812 813 return exit_status; 814 } 815 816 /* Callback for remote forward global requests */ 817 static void 818 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 819 { 820 Forward *rfwd = (Forward *)ctxt; 821 822 /* XXX verbose() on failure? */ 823 debug("remote forward %s for: listen %d, connect %s:%d", 824 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 825 rfwd->listen_port, rfwd->connect_host, rfwd->connect_port); 826 if (type == SSH2_MSG_REQUEST_SUCCESS && rfwd->listen_port == 0) { 827 logit("Allocated port %u for remote forward to %s:%d", 828 packet_get_int(), 829 rfwd->connect_host, rfwd->connect_port); 830 } 831 832 if (type == SSH2_MSG_REQUEST_FAILURE) { 833 if (options.exit_on_forward_failure) 834 fatal("Error: remote port forwarding failed for " 835 "listen port %d", rfwd->listen_port); 836 else 837 logit("Warning: remote port forwarding failed for " 838 "listen port %d", rfwd->listen_port); 839 } 840 if (++remote_forward_confirms_received == options.num_remote_forwards) { 841 debug("All remote forwarding requests processed"); 842 if (fork_after_authentication_flag) { 843 fork_after_authentication_flag = 0; 844 if (daemon(1, 1) < 0) 845 fatal("daemon() failed: %.200s", 846 strerror(errno)); 847 } 848 } 849 } 850 851 static void 852 ssh_init_forwarding(void) 853 { 854 int success = 0; 855 int i; 856 857 /* Initiate local TCP/IP port forwardings. */ 858 for (i = 0; i < options.num_local_forwards; i++) { 859 debug("Local connections to %.200s:%d forwarded to remote " 860 "address %.200s:%d", 861 (options.local_forwards[i].listen_host == NULL) ? 862 (options.gateway_ports ? "*" : "LOCALHOST") : 863 options.local_forwards[i].listen_host, 864 options.local_forwards[i].listen_port, 865 options.local_forwards[i].connect_host, 866 options.local_forwards[i].connect_port); 867 success += channel_setup_local_fwd_listener( 868 options.local_forwards[i].listen_host, 869 options.local_forwards[i].listen_port, 870 options.local_forwards[i].connect_host, 871 options.local_forwards[i].connect_port, 872 options.gateway_ports); 873 } 874 if (i > 0 && success != i && options.exit_on_forward_failure) 875 fatal("Could not request local forwarding."); 876 if (i > 0 && success == 0) 877 error("Could not request local forwarding."); 878 879 /* Initiate remote TCP/IP port forwardings. */ 880 for (i = 0; i < options.num_remote_forwards; i++) { 881 debug("Remote connections from %.200s:%d forwarded to " 882 "local address %.200s:%d", 883 (options.remote_forwards[i].listen_host == NULL) ? 884 "LOCALHOST" : options.remote_forwards[i].listen_host, 885 options.remote_forwards[i].listen_port, 886 options.remote_forwards[i].connect_host, 887 options.remote_forwards[i].connect_port); 888 if (channel_request_remote_forwarding( 889 options.remote_forwards[i].listen_host, 890 options.remote_forwards[i].listen_port, 891 options.remote_forwards[i].connect_host, 892 options.remote_forwards[i].connect_port) < 0) { 893 if (options.exit_on_forward_failure) 894 fatal("Could not request remote forwarding."); 895 else 896 logit("Warning: Could not request remote " 897 "forwarding."); 898 } 899 client_register_global_confirm(ssh_confirm_remote_forward, 900 &options.remote_forwards[i]); 901 } 902 903 /* Initiate tunnel forwarding. */ 904 if (options.tun_open != SSH_TUNMODE_NO) { 905 if (client_request_tun_fwd(options.tun_open, 906 options.tun_local, options.tun_remote) == -1) { 907 if (options.exit_on_forward_failure) 908 fatal("Could not request tunnel forwarding."); 909 else 910 error("Could not request tunnel forwarding."); 911 } 912 } 913 } 914 915 static void 916 check_agent_present(void) 917 { 918 if (options.forward_agent) { 919 /* Clear agent forwarding if we don't have an agent. */ 920 if (!ssh_agent_present()) 921 options.forward_agent = 0; 922 } 923 } 924 925 static int 926 ssh_session(void) 927 { 928 int type; 929 int interactive = 0; 930 int have_tty = 0; 931 struct winsize ws; 932 char *cp; 933 const char *display; 934 935 /* Enable compression if requested. */ 936 if (options.compression) { 937 debug("Requesting compression at level %d.", 938 options.compression_level); 939 940 if (options.compression_level < 1 || 941 options.compression_level > 9) 942 fatal("Compression level must be from 1 (fast) to " 943 "9 (slow, best)."); 944 945 /* Send the request. */ 946 packet_start(SSH_CMSG_REQUEST_COMPRESSION); 947 packet_put_int(options.compression_level); 948 packet_send(); 949 packet_write_wait(); 950 type = packet_read(); 951 if (type == SSH_SMSG_SUCCESS) 952 packet_start_compression(options.compression_level); 953 else if (type == SSH_SMSG_FAILURE) 954 logit("Warning: Remote host refused compression."); 955 else 956 packet_disconnect("Protocol error waiting for " 957 "compression response."); 958 } 959 /* Allocate a pseudo tty if appropriate. */ 960 if (tty_flag) { 961 debug("Requesting pty."); 962 963 /* Start the packet. */ 964 packet_start(SSH_CMSG_REQUEST_PTY); 965 966 /* Store TERM in the packet. There is no limit on the 967 length of the string. */ 968 cp = getenv("TERM"); 969 if (!cp) 970 cp = ""; 971 packet_put_cstring(cp); 972 973 /* Store window size in the packet. */ 974 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) 975 memset(&ws, 0, sizeof(ws)); 976 packet_put_int((u_int)ws.ws_row); 977 packet_put_int((u_int)ws.ws_col); 978 packet_put_int((u_int)ws.ws_xpixel); 979 packet_put_int((u_int)ws.ws_ypixel); 980 981 /* Store tty modes in the packet. */ 982 tty_make_modes(fileno(stdin), NULL); 983 984 /* Send the packet, and wait for it to leave. */ 985 packet_send(); 986 packet_write_wait(); 987 988 /* Read response from the server. */ 989 type = packet_read(); 990 if (type == SSH_SMSG_SUCCESS) { 991 interactive = 1; 992 have_tty = 1; 993 } else if (type == SSH_SMSG_FAILURE) 994 logit("Warning: Remote host failed or refused to " 995 "allocate a pseudo tty."); 996 else 997 packet_disconnect("Protocol error waiting for pty " 998 "request response."); 999 } 1000 /* Request X11 forwarding if enabled and DISPLAY is set. */ 1001 display = getenv("DISPLAY"); 1002 if (options.forward_x11 && display != NULL) { 1003 char *proto, *data; 1004 /* Get reasonable local authentication information. */ 1005 client_x11_get_proto(display, options.xauth_location, 1006 options.forward_x11_trusted, &proto, &data); 1007 /* Request forwarding with authentication spoofing. */ 1008 debug("Requesting X11 forwarding with authentication " 1009 "spoofing."); 1010 x11_request_forwarding_with_spoofing(0, display, proto, data); 1011 1012 /* Read response from the server. */ 1013 type = packet_read(); 1014 if (type == SSH_SMSG_SUCCESS) { 1015 interactive = 1; 1016 } else if (type == SSH_SMSG_FAILURE) { 1017 logit("Warning: Remote host denied X11 forwarding."); 1018 } else { 1019 packet_disconnect("Protocol error waiting for X11 " 1020 "forwarding"); 1021 } 1022 } 1023 /* Tell the packet module whether this is an interactive session. */ 1024 packet_set_interactive(interactive); 1025 1026 /* Request authentication agent forwarding if appropriate. */ 1027 check_agent_present(); 1028 1029 if (options.forward_agent) { 1030 debug("Requesting authentication agent forwarding."); 1031 auth_request_forwarding(); 1032 1033 /* Read response from the server. */ 1034 type = packet_read(); 1035 packet_check_eom(); 1036 if (type != SSH_SMSG_SUCCESS) 1037 logit("Warning: Remote host denied authentication agent forwarding."); 1038 } 1039 1040 /* Initiate port forwardings. */ 1041 ssh_init_forwarding(); 1042 1043 /* Execute a local command */ 1044 if (options.local_command != NULL && 1045 options.permit_local_command) 1046 ssh_local_cmd(options.local_command); 1047 1048 /* 1049 * If requested and we are not interested in replies to remote 1050 * forwarding requests, then let ssh continue in the background. 1051 */ 1052 if (fork_after_authentication_flag && 1053 (!options.exit_on_forward_failure || 1054 options.num_remote_forwards == 0)) { 1055 fork_after_authentication_flag = 0; 1056 if (daemon(1, 1) < 0) 1057 fatal("daemon() failed: %.200s", strerror(errno)); 1058 } 1059 1060 /* 1061 * If a command was specified on the command line, execute the 1062 * command now. Otherwise request the server to start a shell. 1063 */ 1064 if (buffer_len(&command) > 0) { 1065 int len = buffer_len(&command); 1066 if (len > 900) 1067 len = 900; 1068 debug("Sending command: %.*s", len, 1069 (u_char *)buffer_ptr(&command)); 1070 packet_start(SSH_CMSG_EXEC_CMD); 1071 packet_put_string(buffer_ptr(&command), buffer_len(&command)); 1072 packet_send(); 1073 packet_write_wait(); 1074 } else { 1075 debug("Requesting shell."); 1076 packet_start(SSH_CMSG_EXEC_SHELL); 1077 packet_send(); 1078 packet_write_wait(); 1079 } 1080 1081 /* Enter the interactive session. */ 1082 return client_loop(have_tty, tty_flag ? 1083 options.escape_char : SSH_ESCAPECHAR_NONE, 0); 1084 } 1085 1086 /* request pty/x11/agent/tcpfwd/shell for channel */ 1087 static void 1088 ssh_session2_setup(int id, void *arg) 1089 { 1090 extern char **environ; 1091 const char *display; 1092 int interactive = tty_flag; 1093 1094 display = getenv("DISPLAY"); 1095 if (options.forward_x11 && display != NULL) { 1096 char *proto, *data; 1097 /* Get reasonable local authentication information. */ 1098 client_x11_get_proto(display, options.xauth_location, 1099 options.forward_x11_trusted, &proto, &data); 1100 /* Request forwarding with authentication spoofing. */ 1101 debug("Requesting X11 forwarding with authentication " 1102 "spoofing."); 1103 x11_request_forwarding_with_spoofing(id, display, proto, data); 1104 interactive = 1; 1105 /* XXX wait for reply */ 1106 } 1107 1108 check_agent_present(); 1109 if (options.forward_agent) { 1110 debug("Requesting authentication agent forwarding."); 1111 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1112 packet_send(); 1113 } 1114 1115 client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"), 1116 NULL, fileno(stdin), &command, environ); 1117 1118 packet_set_interactive(interactive); 1119 } 1120 1121 /* open new channel for a session */ 1122 static int 1123 ssh_session2_open(void) 1124 { 1125 Channel *c; 1126 int window, packetmax, in, out, err; 1127 1128 if (stdin_null_flag) { 1129 in = open(_PATH_DEVNULL, O_RDONLY); 1130 } else { 1131 in = dup(STDIN_FILENO); 1132 } 1133 out = dup(STDOUT_FILENO); 1134 err = dup(STDERR_FILENO); 1135 1136 if (in < 0 || out < 0 || err < 0) 1137 fatal("dup() in/out/err failed"); 1138 1139 /* enable nonblocking unless tty */ 1140 if (!isatty(in)) 1141 set_nonblock(in); 1142 if (!isatty(out)) 1143 set_nonblock(out); 1144 if (!isatty(err)) 1145 set_nonblock(err); 1146 1147 window = CHAN_SES_WINDOW_DEFAULT; 1148 packetmax = CHAN_SES_PACKET_DEFAULT; 1149 if (tty_flag) { 1150 window >>= 1; 1151 packetmax >>= 1; 1152 } 1153 c = channel_new( 1154 "session", SSH_CHANNEL_OPENING, in, out, err, 1155 window, packetmax, CHAN_EXTENDED_WRITE, 1156 "client-session", /*nonblock*/0); 1157 1158 debug3("ssh_session2_open: channel_new: %d", c->self); 1159 1160 channel_send_open(c->self); 1161 if (!no_shell_flag) 1162 channel_register_open_confirm(c->self, 1163 ssh_session2_setup, NULL); 1164 1165 return c->self; 1166 } 1167 1168 static int 1169 ssh_session2(void) 1170 { 1171 int id = -1; 1172 1173 /* XXX should be pre-session */ 1174 ssh_init_forwarding(); 1175 1176 if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN)) 1177 id = ssh_session2_open(); 1178 1179 /* If we don't expect to open a new session, then disallow it */ 1180 if (options.control_master == SSHCTL_MASTER_NO && 1181 (datafellows & SSH_NEW_OPENSSH)) { 1182 debug("Requesting no-more-sessions@openssh.com"); 1183 packet_start(SSH2_MSG_GLOBAL_REQUEST); 1184 packet_put_cstring("no-more-sessions@openssh.com"); 1185 packet_put_char(0); 1186 packet_send(); 1187 } 1188 1189 /* Execute a local command */ 1190 if (options.local_command != NULL && 1191 options.permit_local_command) 1192 ssh_local_cmd(options.local_command); 1193 1194 /* Start listening for multiplex clients */ 1195 muxserver_listen(); 1196 1197 /* If requested, let ssh continue in the background. */ 1198 if (fork_after_authentication_flag) { 1199 fork_after_authentication_flag = 0; 1200 if (daemon(1, 1) < 0) 1201 fatal("daemon() failed: %.200s", strerror(errno)); 1202 } 1203 1204 return client_loop(tty_flag, tty_flag ? 1205 options.escape_char : SSH_ESCAPECHAR_NONE, id); 1206 } 1207 1208 static void 1209 load_public_identity_files(void) 1210 { 1211 char *filename, *cp, thishost[NI_MAXHOST]; 1212 char *pwdir = NULL, *pwname = NULL; 1213 int i = 0; 1214 Key *public; 1215 struct passwd *pw; 1216 #ifdef SMARTCARD 1217 Key **keys; 1218 1219 if (options.smartcard_device != NULL && 1220 options.num_identity_files < SSH_MAX_IDENTITY_FILES && 1221 (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL) { 1222 int count = 0; 1223 for (i = 0; keys[i] != NULL; i++) { 1224 count++; 1225 memmove(&options.identity_files[1], 1226 &options.identity_files[0], 1227 sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1)); 1228 memmove(&options.identity_keys[1], 1229 &options.identity_keys[0], 1230 sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1)); 1231 options.num_identity_files++; 1232 options.identity_keys[0] = keys[i]; 1233 options.identity_files[0] = sc_get_key_label(keys[i]); 1234 } 1235 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES) 1236 options.num_identity_files = SSH_MAX_IDENTITY_FILES; 1237 i = count; 1238 xfree(keys); 1239 } 1240 #endif /* SMARTCARD */ 1241 if ((pw = getpwuid(original_real_uid)) == NULL) 1242 fatal("load_public_identity_files: getpwuid failed"); 1243 pwname = xstrdup(pw->pw_name); 1244 pwdir = xstrdup(pw->pw_dir); 1245 if (gethostname(thishost, sizeof(thishost)) == -1) 1246 fatal("load_public_identity_files: gethostname: %s", 1247 strerror(errno)); 1248 for (; i < options.num_identity_files; i++) { 1249 cp = tilde_expand_filename(options.identity_files[i], 1250 original_real_uid); 1251 filename = percent_expand(cp, "d", pwdir, 1252 "u", pwname, "l", thishost, "h", host, 1253 "r", options.user, (char *)NULL); 1254 xfree(cp); 1255 public = key_load_public(filename, NULL); 1256 debug("identity file %s type %d", filename, 1257 public ? public->type : -1); 1258 xfree(options.identity_files[i]); 1259 options.identity_files[i] = filename; 1260 options.identity_keys[i] = public; 1261 } 1262 bzero(pwname, strlen(pwname)); 1263 xfree(pwname); 1264 bzero(pwdir, strlen(pwdir)); 1265 xfree(pwdir); 1266 } 1267