1 /* $OpenBSD: ssh.c,v 1.318 2008/07/02 13:47:39 djm 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 "includes.h" 44 __RCSID("$FreeBSD$"); 45 46 #include <sys/types.h> 47 #ifdef HAVE_SYS_STAT_H 48 # include <sys/stat.h> 49 #endif 50 #include <sys/resource.h> 51 #include <sys/ioctl.h> 52 #include <sys/socket.h> 53 54 #include <ctype.h> 55 #include <errno.h> 56 #include <fcntl.h> 57 #include <netdb.h> 58 #ifdef HAVE_PATHS_H 59 #include <paths.h> 60 #endif 61 #include <pwd.h> 62 #include <signal.h> 63 #include <stdarg.h> 64 #include <stddef.h> 65 #include <stdio.h> 66 #include <stdlib.h> 67 #include <string.h> 68 #include <unistd.h> 69 70 #include <netinet/in.h> 71 #include <arpa/inet.h> 72 73 #include <openssl/evp.h> 74 #include <openssl/err.h> 75 #include "openbsd-compat/openssl-compat.h" 76 #include "openbsd-compat/sys-queue.h" 77 78 #include "xmalloc.h" 79 #include "ssh.h" 80 #include "ssh1.h" 81 #include "ssh2.h" 82 #include "compat.h" 83 #include "cipher.h" 84 #include "packet.h" 85 #include "buffer.h" 86 #include "channels.h" 87 #include "key.h" 88 #include "authfd.h" 89 #include "authfile.h" 90 #include "pathnames.h" 91 #include "dispatch.h" 92 #include "clientloop.h" 93 #include "log.h" 94 #include "readconf.h" 95 #include "sshconnect.h" 96 #include "misc.h" 97 #include "kex.h" 98 #include "mac.h" 99 #include "sshpty.h" 100 #include "match.h" 101 #include "msg.h" 102 #include "uidswap.h" 103 #include "version.h" 104 105 #ifdef SMARTCARD 106 #include "scard.h" 107 #endif 108 109 extern char *__progname; 110 111 /* Flag indicating whether debug mode is on. May be set on the command line. */ 112 int debug_flag = 0; 113 114 /* Flag indicating whether a tty should be allocated */ 115 int tty_flag = 0; 116 int no_tty_flag = 0; 117 int force_tty_flag = 0; 118 119 /* don't exec a shell */ 120 int no_shell_flag = 0; 121 122 /* 123 * Flag indicating that nothing should be read from stdin. This can be set 124 * on the command line. 125 */ 126 int stdin_null_flag = 0; 127 128 /* 129 * Flag indicating that ssh should fork after authentication. This is useful 130 * so that the passphrase can be entered manually, and then ssh goes to the 131 * background. 132 */ 133 int fork_after_authentication_flag = 0; 134 135 /* 136 * General data structure for command line options and options configurable 137 * in configuration files. See readconf.h. 138 */ 139 Options options; 140 141 /* optional user configfile */ 142 char *config = NULL; 143 144 /* 145 * Name of the host we are connecting to. This is the name given on the 146 * command line, or the HostName specified for the user-supplied name in a 147 * configuration file. 148 */ 149 char *host; 150 151 /* socket address the host resolves to */ 152 struct sockaddr_storage hostaddr; 153 154 /* Private host keys. */ 155 Sensitive sensitive_data; 156 157 /* Original real UID. */ 158 uid_t original_real_uid; 159 uid_t original_effective_uid; 160 161 /* command to be executed */ 162 Buffer command; 163 164 /* Should we execute a command or invoke a subsystem? */ 165 int subsystem_flag = 0; 166 167 /* # of replies received for global requests */ 168 static int remote_forward_confirms_received = 0; 169 170 /* pid of proxycommand child process */ 171 pid_t proxy_command_pid = 0; 172 173 /* mux.c */ 174 extern int muxserver_sock; 175 extern u_int muxclient_command; 176 177 /* Prints a help message to the user. This function never returns. */ 178 179 static void 180 usage(void) 181 { 182 fprintf(stderr, 183 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n" 184 " [-D [bind_address:]port] [-e escape_char] [-F configfile]\n" 185 " [-i identity_file] [-L [bind_address:]port:host:hostport]\n" 186 " [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n" 187 " [-R [bind_address:]port:host:hostport] [-S ctl_path]\n" 188 " [-w local_tun[:remote_tun]] [user@]hostname [command]\n" 189 ); 190 exit(255); 191 } 192 193 static int ssh_session(void); 194 static int ssh_session2(void); 195 static void load_public_identity_files(void); 196 197 /* from muxclient.c */ 198 void muxclient(const char *); 199 void muxserver_listen(void); 200 201 /* 202 * Main program for the ssh client. 203 */ 204 int 205 main(int ac, char **av) 206 { 207 int i, opt, exit_status; 208 char *p, *cp, *line, buf[256]; 209 struct stat st; 210 struct passwd *pw; 211 int dummy, timeout_ms; 212 extern int optind, optreset; 213 extern char *optarg; 214 struct servent *sp; 215 Forward fwd; 216 217 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 218 sanitise_stdfd(); 219 220 __progname = ssh_get_progname(av[0]); 221 init_rng(); 222 223 /* 224 * Save the original real uid. It will be needed later (uid-swapping 225 * may clobber the real uid). 226 */ 227 original_real_uid = getuid(); 228 original_effective_uid = geteuid(); 229 230 /* 231 * Use uid-swapping to give up root privileges for the duration of 232 * option processing. We will re-instantiate the rights when we are 233 * ready to create the privileged port, and will permanently drop 234 * them when the port has been created (actually, when the connection 235 * has been made, as we may need to create the port several times). 236 */ 237 PRIV_END; 238 239 #ifdef HAVE_SETRLIMIT 240 /* If we are installed setuid root be careful to not drop core. */ 241 if (original_real_uid != original_effective_uid) { 242 struct rlimit rlim; 243 rlim.rlim_cur = rlim.rlim_max = 0; 244 if (setrlimit(RLIMIT_CORE, &rlim) < 0) 245 fatal("setrlimit failed: %.100s", strerror(errno)); 246 } 247 #endif 248 /* Get user data. */ 249 pw = getpwuid(original_real_uid); 250 if (!pw) { 251 logit("You don't exist, go away!"); 252 exit(255); 253 } 254 /* Take a copy of the returned structure. */ 255 pw = pwcopy(pw); 256 257 /* 258 * Set our umask to something reasonable, as some files are created 259 * with the default umask. This will make them world-readable but 260 * writable only by the owner, which is ok for all files for which we 261 * don't set the modes explicitly. 262 */ 263 umask(022); 264 265 /* 266 * Initialize option structure to indicate that no values have been 267 * set. 268 */ 269 initialize_options(&options); 270 271 /* Parse command-line arguments. */ 272 host = NULL; 273 274 again: 275 while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx" 276 "ACD:F:I:KL:MNO:PR:S:TVw:XY")) != -1) { 277 switch (opt) { 278 case '1': 279 options.protocol = SSH_PROTO_1; 280 break; 281 case '2': 282 options.protocol = SSH_PROTO_2; 283 break; 284 case '4': 285 options.address_family = AF_INET; 286 break; 287 case '6': 288 options.address_family = AF_INET6; 289 break; 290 case 'n': 291 stdin_null_flag = 1; 292 break; 293 case 'f': 294 fork_after_authentication_flag = 1; 295 stdin_null_flag = 1; 296 break; 297 case 'x': 298 options.forward_x11 = 0; 299 break; 300 case 'X': 301 options.forward_x11 = 1; 302 break; 303 case 'Y': 304 options.forward_x11 = 1; 305 options.forward_x11_trusted = 1; 306 break; 307 case 'g': 308 options.gateway_ports = 1; 309 break; 310 case 'O': 311 if (strcmp(optarg, "check") == 0) 312 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK; 313 else if (strcmp(optarg, "exit") == 0) 314 muxclient_command = SSHMUX_COMMAND_TERMINATE; 315 else 316 fatal("Invalid multiplex command."); 317 break; 318 case 'P': /* deprecated */ 319 options.use_privileged_port = 0; 320 break; 321 case 'a': 322 options.forward_agent = 0; 323 break; 324 case 'A': 325 options.forward_agent = 1; 326 break; 327 case 'k': 328 options.gss_deleg_creds = 0; 329 break; 330 case 'K': 331 options.gss_authentication = 1; 332 options.gss_deleg_creds = 1; 333 break; 334 case 'i': 335 if (stat(optarg, &st) < 0) { 336 fprintf(stderr, "Warning: Identity file %s " 337 "not accessible: %s.\n", optarg, 338 strerror(errno)); 339 break; 340 } 341 if (options.num_identity_files >= 342 SSH_MAX_IDENTITY_FILES) 343 fatal("Too many identity files specified " 344 "(max %d)", SSH_MAX_IDENTITY_FILES); 345 options.identity_files[options.num_identity_files++] = 346 xstrdup(optarg); 347 break; 348 case 'I': 349 #ifdef SMARTCARD 350 options.smartcard_device = xstrdup(optarg); 351 #else 352 fprintf(stderr, "no support for smartcards.\n"); 353 #endif 354 break; 355 case 't': 356 if (tty_flag) 357 force_tty_flag = 1; 358 tty_flag = 1; 359 break; 360 case 'v': 361 if (debug_flag == 0) { 362 debug_flag = 1; 363 options.log_level = SYSLOG_LEVEL_DEBUG1; 364 } else { 365 if (options.log_level < SYSLOG_LEVEL_DEBUG3) 366 options.log_level++; 367 break; 368 } 369 /* FALLTHROUGH */ 370 case 'V': 371 fprintf(stderr, "%s, %s\n", 372 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); 373 if (opt == 'V') 374 exit(0); 375 break; 376 case 'w': 377 if (options.tun_open == -1) 378 options.tun_open = SSH_TUNMODE_DEFAULT; 379 options.tun_local = a2tun(optarg, &options.tun_remote); 380 if (options.tun_local == SSH_TUNID_ERR) { 381 fprintf(stderr, 382 "Bad tun device '%s'\n", optarg); 383 exit(255); 384 } 385 break; 386 case 'q': 387 options.log_level = SYSLOG_LEVEL_QUIET; 388 break; 389 case 'e': 390 if (optarg[0] == '^' && optarg[2] == 0 && 391 (u_char) optarg[1] >= 64 && 392 (u_char) optarg[1] < 128) 393 options.escape_char = (u_char) optarg[1] & 31; 394 else if (strlen(optarg) == 1) 395 options.escape_char = (u_char) optarg[0]; 396 else if (strcmp(optarg, "none") == 0) 397 options.escape_char = SSH_ESCAPECHAR_NONE; 398 else { 399 fprintf(stderr, "Bad escape character '%s'.\n", 400 optarg); 401 exit(255); 402 } 403 break; 404 case 'c': 405 if (ciphers_valid(optarg)) { 406 /* SSH2 only */ 407 options.ciphers = xstrdup(optarg); 408 options.cipher = SSH_CIPHER_INVALID; 409 } else { 410 /* SSH1 only */ 411 options.cipher = cipher_number(optarg); 412 if (options.cipher == -1) { 413 fprintf(stderr, 414 "Unknown cipher type '%s'\n", 415 optarg); 416 exit(255); 417 } 418 if (options.cipher == SSH_CIPHER_3DES) 419 options.ciphers = "3des-cbc"; 420 else if (options.cipher == SSH_CIPHER_BLOWFISH) 421 options.ciphers = "blowfish-cbc"; 422 else 423 options.ciphers = (char *)-1; 424 } 425 break; 426 case 'm': 427 if (mac_valid(optarg)) 428 options.macs = xstrdup(optarg); 429 else { 430 fprintf(stderr, "Unknown mac type '%s'\n", 431 optarg); 432 exit(255); 433 } 434 break; 435 case 'M': 436 if (options.control_master == SSHCTL_MASTER_YES) 437 options.control_master = SSHCTL_MASTER_ASK; 438 else 439 options.control_master = SSHCTL_MASTER_YES; 440 break; 441 case 'p': 442 options.port = a2port(optarg); 443 if (options.port == 0) { 444 fprintf(stderr, "Bad port '%s'\n", optarg); 445 exit(255); 446 } 447 break; 448 case 'l': 449 options.user = optarg; 450 break; 451 452 case 'L': 453 if (parse_forward(&fwd, optarg)) 454 add_local_forward(&options, &fwd); 455 else { 456 fprintf(stderr, 457 "Bad local forwarding specification '%s'\n", 458 optarg); 459 exit(255); 460 } 461 break; 462 463 case 'R': 464 if (parse_forward(&fwd, optarg)) { 465 add_remote_forward(&options, &fwd); 466 } else { 467 fprintf(stderr, 468 "Bad remote forwarding specification " 469 "'%s'\n", optarg); 470 exit(255); 471 } 472 break; 473 474 case 'D': 475 cp = p = xstrdup(optarg); 476 memset(&fwd, '\0', sizeof(fwd)); 477 fwd.connect_host = "socks"; 478 if ((fwd.listen_host = hpdelim(&cp)) == NULL) { 479 fprintf(stderr, "Bad dynamic forwarding " 480 "specification '%.100s'\n", optarg); 481 exit(255); 482 } 483 if (cp != NULL) { 484 fwd.listen_port = a2port(cp); 485 fwd.listen_host = 486 cleanhostname(fwd.listen_host); 487 } else { 488 fwd.listen_port = a2port(fwd.listen_host); 489 fwd.listen_host = NULL; 490 } 491 492 if (fwd.listen_port == 0) { 493 fprintf(stderr, "Bad dynamic port '%s'\n", 494 optarg); 495 exit(255); 496 } 497 add_local_forward(&options, &fwd); 498 xfree(p); 499 break; 500 501 case 'C': 502 options.compression = 1; 503 break; 504 case 'N': 505 no_shell_flag = 1; 506 no_tty_flag = 1; 507 break; 508 case 'T': 509 no_tty_flag = 1; 510 break; 511 case 'o': 512 dummy = 1; 513 line = xstrdup(optarg); 514 if (process_config_line(&options, host ? host : "", 515 line, "command-line", 0, &dummy) != 0) 516 exit(255); 517 xfree(line); 518 break; 519 case 's': 520 subsystem_flag = 1; 521 break; 522 case 'S': 523 if (options.control_path != NULL) 524 free(options.control_path); 525 options.control_path = xstrdup(optarg); 526 break; 527 case 'b': 528 options.bind_address = optarg; 529 break; 530 case 'F': 531 config = optarg; 532 break; 533 default: 534 usage(); 535 } 536 } 537 538 ac -= optind; 539 av += optind; 540 541 if (ac > 0 && !host && **av != '-') { 542 if (strrchr(*av, '@')) { 543 p = xstrdup(*av); 544 cp = strrchr(p, '@'); 545 if (cp == NULL || cp == p) 546 usage(); 547 options.user = p; 548 *cp = '\0'; 549 host = ++cp; 550 } else 551 host = *av; 552 if (ac > 1) { 553 optind = optreset = 1; 554 goto again; 555 } 556 ac--, av++; 557 } 558 559 /* Check that we got a host name. */ 560 if (!host) 561 usage(); 562 563 SSLeay_add_all_algorithms(); 564 ERR_load_crypto_strings(); 565 566 /* Initialize the command to execute on remote host. */ 567 buffer_init(&command); 568 569 /* 570 * Save the command to execute on the remote host in a buffer. There 571 * is no limit on the length of the command, except by the maximum 572 * packet size. Also sets the tty flag if there is no command. 573 */ 574 if (!ac) { 575 /* No command specified - execute shell on a tty. */ 576 tty_flag = 1; 577 if (subsystem_flag) { 578 fprintf(stderr, 579 "You must specify a subsystem to invoke.\n"); 580 usage(); 581 } 582 } else { 583 /* A command has been specified. Store it into the buffer. */ 584 for (i = 0; i < ac; i++) { 585 if (i) 586 buffer_append(&command, " ", 1); 587 buffer_append(&command, av[i], strlen(av[i])); 588 } 589 } 590 591 /* Cannot fork to background if no command. */ 592 if (fork_after_authentication_flag && buffer_len(&command) == 0 && 593 !no_shell_flag) 594 fatal("Cannot fork into background without a command " 595 "to execute."); 596 597 /* Allocate a tty by default if no command specified. */ 598 if (buffer_len(&command) == 0) 599 tty_flag = 1; 600 601 /* Force no tty */ 602 if (no_tty_flag) 603 tty_flag = 0; 604 /* Do not allocate a tty if stdin is not a tty. */ 605 if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) { 606 if (tty_flag) 607 logit("Pseudo-terminal will not be allocated because " 608 "stdin is not a terminal."); 609 tty_flag = 0; 610 } 611 612 /* 613 * Initialize "log" output. Since we are the client all output 614 * actually goes to stderr. 615 */ 616 log_init(av[0], 617 options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level, 618 SYSLOG_FACILITY_USER, 1); 619 620 /* 621 * Read per-user configuration file. Ignore the system wide config 622 * file if the user specifies a config file on the command line. 623 */ 624 if (config != NULL) { 625 if (!read_config_file(config, host, &options, 0)) 626 fatal("Can't open user config file %.100s: " 627 "%.100s", config, strerror(errno)); 628 } else { 629 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, 630 _PATH_SSH_USER_CONFFILE); 631 (void)read_config_file(buf, host, &options, 1); 632 633 /* Read systemwide configuration file after use config. */ 634 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, 635 &options, 0); 636 } 637 638 /* Fill configuration defaults. */ 639 fill_default_options(&options); 640 641 channel_set_af(options.address_family); 642 643 /* reinit */ 644 log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1); 645 646 seed_rng(); 647 648 if (options.user == NULL) 649 options.user = xstrdup(pw->pw_name); 650 651 /* Get default port if port has not been set. */ 652 if (options.port == 0) { 653 sp = getservbyname(SSH_SERVICE_NAME, "tcp"); 654 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT; 655 } 656 657 if (options.local_command != NULL) { 658 char thishost[NI_MAXHOST]; 659 660 if (gethostname(thishost, sizeof(thishost)) == -1) 661 fatal("gethostname: %s", strerror(errno)); 662 snprintf(buf, sizeof(buf), "%d", options.port); 663 debug3("expanding LocalCommand: %s", options.local_command); 664 cp = options.local_command; 665 options.local_command = percent_expand(cp, "d", pw->pw_dir, 666 "h", options.hostname? options.hostname : host, 667 "l", thishost, "n", host, "r", options.user, "p", buf, 668 "u", pw->pw_name, (char *)NULL); 669 debug3("expanded LocalCommand: %s", options.local_command); 670 xfree(cp); 671 } 672 673 if (options.hostname != NULL) 674 host = options.hostname; 675 676 /* Find canonic host name. */ 677 if (strchr(host, '.') == 0) { 678 struct addrinfo hints; 679 struct addrinfo *ai = NULL; 680 int errgai; 681 memset(&hints, 0, sizeof(hints)); 682 hints.ai_family = options.address_family; 683 hints.ai_flags = AI_CANONNAME; 684 hints.ai_socktype = SOCK_STREAM; 685 errgai = getaddrinfo(host, NULL, &hints, &ai); 686 if (errgai == 0) { 687 if (ai->ai_canonname != NULL) 688 host = xstrdup(ai->ai_canonname); 689 freeaddrinfo(ai); 690 } 691 } 692 693 /* force lowercase for hostkey matching */ 694 if (options.host_key_alias != NULL) { 695 for (p = options.host_key_alias; *p; p++) 696 if (isupper(*p)) 697 *p = (char)tolower(*p); 698 } 699 700 if (options.proxy_command != NULL && 701 strcmp(options.proxy_command, "none") == 0) { 702 xfree(options.proxy_command); 703 options.proxy_command = NULL; 704 } 705 if (options.control_path != NULL && 706 strcmp(options.control_path, "none") == 0) { 707 xfree(options.control_path); 708 options.control_path = NULL; 709 } 710 711 if (options.control_path != NULL) { 712 char thishost[NI_MAXHOST]; 713 714 if (gethostname(thishost, sizeof(thishost)) == -1) 715 fatal("gethostname: %s", strerror(errno)); 716 snprintf(buf, sizeof(buf), "%d", options.port); 717 cp = tilde_expand_filename(options.control_path, 718 original_real_uid); 719 xfree(options.control_path); 720 options.control_path = percent_expand(cp, "p", buf, "h", host, 721 "r", options.user, "l", thishost, (char *)NULL); 722 xfree(cp); 723 } 724 if (muxclient_command != 0 && options.control_path == NULL) 725 fatal("No ControlPath specified for \"-O\" command"); 726 if (options.control_path != NULL) 727 muxclient(options.control_path); 728 729 timeout_ms = options.connection_timeout * 1000; 730 731 /* Open a connection to the remote host. */ 732 if (ssh_connect(host, &hostaddr, options.port, 733 options.address_family, options.connection_attempts, &timeout_ms, 734 options.tcp_keep_alive, 735 #ifdef HAVE_CYGWIN 736 options.use_privileged_port, 737 #else 738 original_effective_uid == 0 && options.use_privileged_port, 739 #endif 740 options.proxy_command) != 0) 741 exit(255); 742 743 if (timeout_ms > 0) 744 debug3("timeout: %d ms remain after connect", timeout_ms); 745 746 /* 747 * If we successfully made the connection, load the host private key 748 * in case we will need it later for combined rsa-rhosts 749 * authentication. This must be done before releasing extra 750 * privileges, because the file is only readable by root. 751 * If we cannot access the private keys, load the public keys 752 * instead and try to execute the ssh-keysign helper instead. 753 */ 754 sensitive_data.nkeys = 0; 755 sensitive_data.keys = NULL; 756 sensitive_data.external_keysign = 0; 757 if (options.rhosts_rsa_authentication || 758 options.hostbased_authentication) { 759 sensitive_data.nkeys = 3; 760 sensitive_data.keys = xcalloc(sensitive_data.nkeys, 761 sizeof(Key)); 762 763 PRIV_START; 764 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1, 765 _PATH_HOST_KEY_FILE, "", NULL, NULL); 766 sensitive_data.keys[1] = key_load_private_type(KEY_DSA, 767 _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL); 768 sensitive_data.keys[2] = key_load_private_type(KEY_RSA, 769 _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL); 770 PRIV_END; 771 772 if (options.hostbased_authentication == 1 && 773 sensitive_data.keys[0] == NULL && 774 sensitive_data.keys[1] == NULL && 775 sensitive_data.keys[2] == NULL) { 776 sensitive_data.keys[1] = key_load_public( 777 _PATH_HOST_DSA_KEY_FILE, NULL); 778 sensitive_data.keys[2] = key_load_public( 779 _PATH_HOST_RSA_KEY_FILE, NULL); 780 sensitive_data.external_keysign = 1; 781 } 782 } 783 /* 784 * Get rid of any extra privileges that we may have. We will no 785 * longer need them. Also, extra privileges could make it very hard 786 * to read identity files and other non-world-readable files from the 787 * user's home directory if it happens to be on a NFS volume where 788 * root is mapped to nobody. 789 */ 790 if (original_effective_uid == 0) { 791 PRIV_START; 792 permanently_set_uid(pw); 793 } 794 795 /* 796 * Now that we are back to our own permissions, create ~/.ssh 797 * directory if it doesn't already exist. 798 */ 799 snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, 800 strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR); 801 if (stat(buf, &st) < 0) 802 if (mkdir(buf, 0700) < 0) 803 error("Could not create directory '%.200s'.", buf); 804 805 /* load options.identity_files */ 806 load_public_identity_files(); 807 808 /* Expand ~ in known host file names. */ 809 /* XXX mem-leaks: */ 810 options.system_hostfile = 811 tilde_expand_filename(options.system_hostfile, original_real_uid); 812 options.user_hostfile = 813 tilde_expand_filename(options.user_hostfile, original_real_uid); 814 options.system_hostfile2 = 815 tilde_expand_filename(options.system_hostfile2, original_real_uid); 816 options.user_hostfile2 = 817 tilde_expand_filename(options.user_hostfile2, original_real_uid); 818 819 signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */ 820 821 /* Log into the remote system. Never returns if the login fails. */ 822 ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, 823 pw, timeout_ms); 824 825 /* We no longer need the private host keys. Clear them now. */ 826 if (sensitive_data.nkeys != 0) { 827 for (i = 0; i < sensitive_data.nkeys; i++) { 828 if (sensitive_data.keys[i] != NULL) { 829 /* Destroys contents safely */ 830 debug3("clear hostkey %d", i); 831 key_free(sensitive_data.keys[i]); 832 sensitive_data.keys[i] = NULL; 833 } 834 } 835 xfree(sensitive_data.keys); 836 } 837 for (i = 0; i < options.num_identity_files; i++) { 838 if (options.identity_files[i]) { 839 xfree(options.identity_files[i]); 840 options.identity_files[i] = NULL; 841 } 842 if (options.identity_keys[i]) { 843 key_free(options.identity_keys[i]); 844 options.identity_keys[i] = NULL; 845 } 846 } 847 848 exit_status = compat20 ? ssh_session2() : ssh_session(); 849 packet_close(); 850 851 if (options.control_path != NULL && muxserver_sock != -1) 852 unlink(options.control_path); 853 854 /* 855 * Send SIGHUP to proxy command if used. We don't wait() in 856 * case it hangs and instead rely on init to reap the child 857 */ 858 if (proxy_command_pid > 1) 859 kill(proxy_command_pid, SIGHUP); 860 861 return exit_status; 862 } 863 864 /* Callback for remote forward global requests */ 865 static void 866 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) 867 { 868 Forward *rfwd = (Forward *)ctxt; 869 870 debug("remote forward %s for: listen %d, connect %s:%d", 871 type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", 872 rfwd->listen_port, rfwd->connect_host, rfwd->connect_port); 873 if (type == SSH2_MSG_REQUEST_FAILURE) { 874 if (options.exit_on_forward_failure) 875 fatal("Error: remote port forwarding failed for " 876 "listen port %d", rfwd->listen_port); 877 else 878 logit("Warning: remote port forwarding failed for " 879 "listen port %d", rfwd->listen_port); 880 } 881 if (++remote_forward_confirms_received == options.num_remote_forwards) { 882 debug("All remote forwarding requests processed"); 883 if (fork_after_authentication_flag) { 884 fork_after_authentication_flag = 0; 885 if (daemon(1, 1) < 0) 886 fatal("daemon() failed: %.200s", 887 strerror(errno)); 888 } 889 } 890 } 891 892 static void 893 ssh_init_forwarding(void) 894 { 895 int success = 0; 896 int i; 897 898 /* Initiate local TCP/IP port forwardings. */ 899 for (i = 0; i < options.num_local_forwards; i++) { 900 debug("Local connections to %.200s:%d forwarded to remote " 901 "address %.200s:%d", 902 (options.local_forwards[i].listen_host == NULL) ? 903 (options.gateway_ports ? "*" : "LOCALHOST") : 904 options.local_forwards[i].listen_host, 905 options.local_forwards[i].listen_port, 906 options.local_forwards[i].connect_host, 907 options.local_forwards[i].connect_port); 908 success += channel_setup_local_fwd_listener( 909 options.local_forwards[i].listen_host, 910 options.local_forwards[i].listen_port, 911 options.local_forwards[i].connect_host, 912 options.local_forwards[i].connect_port, 913 options.gateway_ports); 914 } 915 if (i > 0 && success != i && options.exit_on_forward_failure) 916 fatal("Could not request local forwarding."); 917 if (i > 0 && success == 0) 918 error("Could not request local forwarding."); 919 920 /* Initiate remote TCP/IP port forwardings. */ 921 for (i = 0; i < options.num_remote_forwards; i++) { 922 debug("Remote connections from %.200s:%d forwarded to " 923 "local address %.200s:%d", 924 (options.remote_forwards[i].listen_host == NULL) ? 925 "LOCALHOST" : options.remote_forwards[i].listen_host, 926 options.remote_forwards[i].listen_port, 927 options.remote_forwards[i].connect_host, 928 options.remote_forwards[i].connect_port); 929 if (channel_request_remote_forwarding( 930 options.remote_forwards[i].listen_host, 931 options.remote_forwards[i].listen_port, 932 options.remote_forwards[i].connect_host, 933 options.remote_forwards[i].connect_port) < 0) { 934 if (options.exit_on_forward_failure) 935 fatal("Could not request remote forwarding."); 936 else 937 logit("Warning: Could not request remote " 938 "forwarding."); 939 } 940 client_register_global_confirm(ssh_confirm_remote_forward, 941 &options.remote_forwards[i]); 942 } 943 944 /* Initiate tunnel forwarding. */ 945 if (options.tun_open != SSH_TUNMODE_NO) { 946 if (client_request_tun_fwd(options.tun_open, 947 options.tun_local, options.tun_remote) == -1) { 948 if (options.exit_on_forward_failure) 949 fatal("Could not request tunnel forwarding."); 950 else 951 error("Could not request tunnel forwarding."); 952 } 953 } 954 } 955 956 static void 957 check_agent_present(void) 958 { 959 if (options.forward_agent) { 960 /* Clear agent forwarding if we don't have an agent. */ 961 if (!ssh_agent_present()) 962 options.forward_agent = 0; 963 } 964 } 965 966 static int 967 ssh_session(void) 968 { 969 int type; 970 int interactive = 0; 971 int have_tty = 0; 972 struct winsize ws; 973 char *cp; 974 const char *display; 975 976 /* Enable compression if requested. */ 977 if (options.compression) { 978 debug("Requesting compression at level %d.", 979 options.compression_level); 980 981 if (options.compression_level < 1 || 982 options.compression_level > 9) 983 fatal("Compression level must be from 1 (fast) to " 984 "9 (slow, best)."); 985 986 /* Send the request. */ 987 packet_start(SSH_CMSG_REQUEST_COMPRESSION); 988 packet_put_int(options.compression_level); 989 packet_send(); 990 packet_write_wait(); 991 type = packet_read(); 992 if (type == SSH_SMSG_SUCCESS) 993 packet_start_compression(options.compression_level); 994 else if (type == SSH_SMSG_FAILURE) 995 logit("Warning: Remote host refused compression."); 996 else 997 packet_disconnect("Protocol error waiting for " 998 "compression response."); 999 } 1000 /* Allocate a pseudo tty if appropriate. */ 1001 if (tty_flag) { 1002 debug("Requesting pty."); 1003 1004 /* Start the packet. */ 1005 packet_start(SSH_CMSG_REQUEST_PTY); 1006 1007 /* Store TERM in the packet. There is no limit on the 1008 length of the string. */ 1009 cp = getenv("TERM"); 1010 if (!cp) 1011 cp = ""; 1012 packet_put_cstring(cp); 1013 1014 /* Store window size in the packet. */ 1015 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) 1016 memset(&ws, 0, sizeof(ws)); 1017 packet_put_int((u_int)ws.ws_row); 1018 packet_put_int((u_int)ws.ws_col); 1019 packet_put_int((u_int)ws.ws_xpixel); 1020 packet_put_int((u_int)ws.ws_ypixel); 1021 1022 /* Store tty modes in the packet. */ 1023 tty_make_modes(fileno(stdin), NULL); 1024 1025 /* Send the packet, and wait for it to leave. */ 1026 packet_send(); 1027 packet_write_wait(); 1028 1029 /* Read response from the server. */ 1030 type = packet_read(); 1031 if (type == SSH_SMSG_SUCCESS) { 1032 interactive = 1; 1033 have_tty = 1; 1034 } else if (type == SSH_SMSG_FAILURE) 1035 logit("Warning: Remote host failed or refused to " 1036 "allocate a pseudo tty."); 1037 else 1038 packet_disconnect("Protocol error waiting for pty " 1039 "request response."); 1040 } 1041 /* Request X11 forwarding if enabled and DISPLAY is set. */ 1042 display = getenv("DISPLAY"); 1043 if (options.forward_x11 && display != NULL) { 1044 char *proto, *data; 1045 /* Get reasonable local authentication information. */ 1046 client_x11_get_proto(display, options.xauth_location, 1047 options.forward_x11_trusted, &proto, &data); 1048 /* Request forwarding with authentication spoofing. */ 1049 debug("Requesting X11 forwarding with authentication " 1050 "spoofing."); 1051 x11_request_forwarding_with_spoofing(0, display, proto, data); 1052 1053 /* Read response from the server. */ 1054 type = packet_read(); 1055 if (type == SSH_SMSG_SUCCESS) { 1056 interactive = 1; 1057 } else if (type == SSH_SMSG_FAILURE) { 1058 logit("Warning: Remote host denied X11 forwarding."); 1059 } else { 1060 packet_disconnect("Protocol error waiting for X11 " 1061 "forwarding"); 1062 } 1063 } 1064 /* Tell the packet module whether this is an interactive session. */ 1065 packet_set_interactive(interactive); 1066 1067 /* Request authentication agent forwarding if appropriate. */ 1068 check_agent_present(); 1069 1070 if (options.forward_agent) { 1071 debug("Requesting authentication agent forwarding."); 1072 auth_request_forwarding(); 1073 1074 /* Read response from the server. */ 1075 type = packet_read(); 1076 packet_check_eom(); 1077 if (type != SSH_SMSG_SUCCESS) 1078 logit("Warning: Remote host denied authentication agent forwarding."); 1079 } 1080 1081 /* Initiate port forwardings. */ 1082 ssh_init_forwarding(); 1083 1084 /* Execute a local command */ 1085 if (options.local_command != NULL && 1086 options.permit_local_command) 1087 ssh_local_cmd(options.local_command); 1088 1089 /* 1090 * If requested and we are not interested in replies to remote 1091 * forwarding requests, then let ssh continue in the background. 1092 */ 1093 if (fork_after_authentication_flag && 1094 (!options.exit_on_forward_failure || 1095 options.num_remote_forwards == 0)) { 1096 fork_after_authentication_flag = 0; 1097 if (daemon(1, 1) < 0) 1098 fatal("daemon() failed: %.200s", strerror(errno)); 1099 } 1100 1101 /* 1102 * If a command was specified on the command line, execute the 1103 * command now. Otherwise request the server to start a shell. 1104 */ 1105 if (buffer_len(&command) > 0) { 1106 int len = buffer_len(&command); 1107 if (len > 900) 1108 len = 900; 1109 debug("Sending command: %.*s", len, 1110 (u_char *)buffer_ptr(&command)); 1111 packet_start(SSH_CMSG_EXEC_CMD); 1112 packet_put_string(buffer_ptr(&command), buffer_len(&command)); 1113 packet_send(); 1114 packet_write_wait(); 1115 } else { 1116 debug("Requesting shell."); 1117 packet_start(SSH_CMSG_EXEC_SHELL); 1118 packet_send(); 1119 packet_write_wait(); 1120 } 1121 1122 /* Enter the interactive session. */ 1123 return client_loop(have_tty, tty_flag ? 1124 options.escape_char : SSH_ESCAPECHAR_NONE, 0); 1125 } 1126 1127 /* request pty/x11/agent/tcpfwd/shell for channel */ 1128 static void 1129 ssh_session2_setup(int id, void *arg) 1130 { 1131 extern char **environ; 1132 const char *display; 1133 int interactive = tty_flag; 1134 1135 display = getenv("DISPLAY"); 1136 if (options.forward_x11 && display != NULL) { 1137 char *proto, *data; 1138 /* Get reasonable local authentication information. */ 1139 client_x11_get_proto(display, options.xauth_location, 1140 options.forward_x11_trusted, &proto, &data); 1141 /* Request forwarding with authentication spoofing. */ 1142 debug("Requesting X11 forwarding with authentication " 1143 "spoofing."); 1144 x11_request_forwarding_with_spoofing(id, display, proto, data); 1145 interactive = 1; 1146 /* XXX wait for reply */ 1147 } 1148 1149 check_agent_present(); 1150 if (options.forward_agent) { 1151 debug("Requesting authentication agent forwarding."); 1152 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1153 packet_send(); 1154 } 1155 1156 client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"), 1157 NULL, fileno(stdin), &command, environ); 1158 1159 packet_set_interactive(interactive); 1160 } 1161 1162 /* open new channel for a session */ 1163 static int 1164 ssh_session2_open(void) 1165 { 1166 Channel *c; 1167 int window, packetmax, in, out, err; 1168 1169 if (stdin_null_flag) { 1170 in = open(_PATH_DEVNULL, O_RDONLY); 1171 } else { 1172 in = dup(STDIN_FILENO); 1173 } 1174 out = dup(STDOUT_FILENO); 1175 err = dup(STDERR_FILENO); 1176 1177 if (in < 0 || out < 0 || err < 0) 1178 fatal("dup() in/out/err failed"); 1179 1180 /* enable nonblocking unless tty */ 1181 if (!isatty(in)) 1182 set_nonblock(in); 1183 if (!isatty(out)) 1184 set_nonblock(out); 1185 if (!isatty(err)) 1186 set_nonblock(err); 1187 1188 window = CHAN_SES_WINDOW_DEFAULT; 1189 packetmax = CHAN_SES_PACKET_DEFAULT; 1190 if (tty_flag) { 1191 window >>= 1; 1192 packetmax >>= 1; 1193 } 1194 c = channel_new( 1195 "session", SSH_CHANNEL_OPENING, in, out, err, 1196 window, packetmax, CHAN_EXTENDED_WRITE, 1197 "client-session", /*nonblock*/0); 1198 1199 debug3("ssh_session2_open: channel_new: %d", c->self); 1200 1201 channel_send_open(c->self); 1202 if (!no_shell_flag) 1203 channel_register_open_confirm(c->self, 1204 ssh_session2_setup, NULL); 1205 1206 return c->self; 1207 } 1208 1209 static int 1210 ssh_session2(void) 1211 { 1212 int id = -1; 1213 1214 /* XXX should be pre-session */ 1215 ssh_init_forwarding(); 1216 1217 if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN)) 1218 id = ssh_session2_open(); 1219 1220 /* If we don't expect to open a new session, then disallow it */ 1221 if (options.control_master == SSHCTL_MASTER_NO) { 1222 debug("Requesting no-more-sessions@openssh.com"); 1223 packet_start(SSH2_MSG_GLOBAL_REQUEST); 1224 packet_put_cstring("no-more-sessions@openssh.com"); 1225 packet_put_char(0); 1226 packet_send(); 1227 } 1228 1229 /* Execute a local command */ 1230 if (options.local_command != NULL && 1231 options.permit_local_command) 1232 ssh_local_cmd(options.local_command); 1233 1234 /* Start listening for multiplex clients */ 1235 muxserver_listen(); 1236 1237 /* If requested, let ssh continue in the background. */ 1238 if (fork_after_authentication_flag) { 1239 fork_after_authentication_flag = 0; 1240 if (daemon(1, 1) < 0) 1241 fatal("daemon() failed: %.200s", strerror(errno)); 1242 } 1243 1244 return client_loop(tty_flag, tty_flag ? 1245 options.escape_char : SSH_ESCAPECHAR_NONE, id); 1246 } 1247 1248 static void 1249 load_public_identity_files(void) 1250 { 1251 char *filename, *cp, thishost[NI_MAXHOST]; 1252 char *pwdir = NULL, *pwname = NULL; 1253 int i = 0; 1254 Key *public; 1255 struct passwd *pw; 1256 #ifdef SMARTCARD 1257 Key **keys; 1258 1259 if (options.smartcard_device != NULL && 1260 options.num_identity_files < SSH_MAX_IDENTITY_FILES && 1261 (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL) { 1262 int count = 0; 1263 for (i = 0; keys[i] != NULL; i++) { 1264 count++; 1265 memmove(&options.identity_files[1], 1266 &options.identity_files[0], 1267 sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1)); 1268 memmove(&options.identity_keys[1], 1269 &options.identity_keys[0], 1270 sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1)); 1271 options.num_identity_files++; 1272 options.identity_keys[0] = keys[i]; 1273 options.identity_files[0] = sc_get_key_label(keys[i]); 1274 } 1275 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES) 1276 options.num_identity_files = SSH_MAX_IDENTITY_FILES; 1277 i = count; 1278 xfree(keys); 1279 } 1280 #endif /* SMARTCARD */ 1281 if ((pw = getpwuid(original_real_uid)) == NULL) 1282 fatal("load_public_identity_files: getpwuid failed"); 1283 pwname = xstrdup(pw->pw_name); 1284 pwdir = xstrdup(pw->pw_dir); 1285 if (gethostname(thishost, sizeof(thishost)) == -1) 1286 fatal("load_public_identity_files: gethostname: %s", 1287 strerror(errno)); 1288 for (; i < options.num_identity_files; i++) { 1289 cp = tilde_expand_filename(options.identity_files[i], 1290 original_real_uid); 1291 filename = percent_expand(cp, "d", pwdir, 1292 "u", pwname, "l", thishost, "h", host, 1293 "r", options.user, (char *)NULL); 1294 xfree(cp); 1295 public = key_load_public(filename, NULL); 1296 debug("identity file %s type %d", filename, 1297 public ? public->type : -1); 1298 xfree(options.identity_files[i]); 1299 options.identity_files[i] = filename; 1300 options.identity_keys[i] = public; 1301 } 1302 bzero(pwname, strlen(pwname)); 1303 xfree(pwname); 1304 bzero(pwdir, strlen(pwdir)); 1305 xfree(pwdir); 1306 } 1307