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 * 17 * Modified to work with SSL by Niels Provos <provos@citi.umich.edu> 18 * in Canada (German citizen). 19 * 20 * Redistribution and use in source and binary forms, with or without 21 * modification, are permitted provided that the following conditions 22 * are met: 23 * 1. Redistributions of source code must retain the above copyright 24 * notice, this list of conditions and the following disclaimer. 25 * 2. Redistributions in binary form must reproduce the above copyright 26 * notice, this list of conditions and the following disclaimer in the 27 * documentation and/or other materials provided with the distribution. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 30 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 31 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 32 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 33 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 34 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 38 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 39 */ 40 41 #include "includes.h" 42 RCSID("$OpenBSD: ssh.c,v 1.143 2001/09/20 13:50:40 markus Exp $"); 43 44 #include <openssl/evp.h> 45 #include <openssl/err.h> 46 47 #include "ssh.h" 48 #include "ssh1.h" 49 #include "ssh2.h" 50 #include "compat.h" 51 #include "cipher.h" 52 #include "xmalloc.h" 53 #include "packet.h" 54 #include "buffer.h" 55 #include "uidswap.h" 56 #include "channels.h" 57 #include "key.h" 58 #include "authfd.h" 59 #include "authfile.h" 60 #include "pathnames.h" 61 #include "clientloop.h" 62 #include "log.h" 63 #include "readconf.h" 64 #include "sshconnect.h" 65 #include "tildexpand.h" 66 #include "dispatch.h" 67 #include "misc.h" 68 #include "kex.h" 69 #include "mac.h" 70 #include "sshtty.h" 71 72 #ifdef SMARTCARD 73 #include <openssl/engine.h> 74 #include "scard.h" 75 #endif 76 77 extern char *__progname; 78 79 /* Flag indicating whether IPv4 or IPv6. This can be set on the command line. 80 Default value is AF_UNSPEC means both IPv4 and IPv6. */ 81 int IPv4or6 = AF_UNSPEC; 82 83 /* Flag indicating whether debug mode is on. This can be set on the command line. */ 84 int debug_flag = 0; 85 86 /* Flag indicating whether a tty should be allocated */ 87 int tty_flag = 0; 88 int no_tty_flag = 0; 89 int force_tty_flag = 0; 90 91 /* don't exec a shell */ 92 int no_shell_flag = 0; 93 94 /* 95 * Flag indicating that nothing should be read from stdin. This can be set 96 * on the command line. 97 */ 98 int stdin_null_flag = 0; 99 100 /* 101 * Flag indicating that ssh should fork after authentication. This is useful 102 * so that the pasphrase can be entered manually, and then ssh goes to the 103 * background. 104 */ 105 int fork_after_authentication_flag = 0; 106 107 /* 108 * General data structure for command line options and options configurable 109 * in configuration files. See readconf.h. 110 */ 111 Options options; 112 113 /* optional user configfile */ 114 char *config = NULL; 115 116 /* 117 * Name of the host we are connecting to. This is the name given on the 118 * command line, or the HostName specified for the user-supplied name in a 119 * configuration file. 120 */ 121 char *host; 122 123 /* socket address the host resolves to */ 124 struct sockaddr_storage hostaddr; 125 126 /* 127 * Flag to indicate that we have received a window change signal which has 128 * not yet been processed. This will cause a message indicating the new 129 * window size to be sent to the server a little later. This is volatile 130 * because this is updated in a signal handler. 131 */ 132 volatile int received_window_change_signal = 0; 133 134 /* Private host keys. */ 135 struct { 136 Key **keys; 137 int nkeys; 138 } sensitive_data; 139 140 /* Original real UID. */ 141 uid_t original_real_uid; 142 143 /* command to be executed */ 144 Buffer command; 145 146 /* Should we execute a command or invoke a subsystem? */ 147 int subsystem_flag = 0; 148 149 /* Prints a help message to the user. This function never returns. */ 150 151 static void 152 usage(void) 153 { 154 fprintf(stderr, "Usage: %s [options] host [command]\n", __progname); 155 fprintf(stderr, "Options:\n"); 156 fprintf(stderr, " -l user Log in using this user name.\n"); 157 fprintf(stderr, " -n Redirect input from " _PATH_DEVNULL ".\n"); 158 fprintf(stderr, " -F config Config file (default: ~/%s).\n", 159 _PATH_SSH_USER_CONFFILE); 160 fprintf(stderr, " -A Enable authentication agent forwarding.\n"); 161 fprintf(stderr, " -a Disable authentication agent forwarding (default).\n"); 162 #ifdef AFS 163 fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n"); 164 #endif /* AFS */ 165 fprintf(stderr, " -X Enable X11 connection forwarding.\n"); 166 fprintf(stderr, " -x Disable X11 connection forwarding (default).\n"); 167 fprintf(stderr, " -i file Identity for public key authentication " 168 "(default: ~/.ssh/identity)\n"); 169 #ifdef SMARTCARD 170 fprintf(stderr, " -I reader Set smartcard reader.\n"); 171 #endif 172 fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n"); 173 fprintf(stderr, " -T Do not allocate a tty.\n"); 174 fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); 175 fprintf(stderr, " Multiple -v increases verbosity.\n"); 176 fprintf(stderr, " -V Display version number only.\n"); 177 fprintf(stderr, " -P Don't allocate a privileged port.\n"); 178 fprintf(stderr, " -q Quiet; don't display any warning messages.\n"); 179 fprintf(stderr, " -f Fork into background after authentication.\n"); 180 fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n"); 181 182 fprintf(stderr, " -c cipher Select encryption algorithm\n"); 183 fprintf(stderr, " -m macs Specify MAC algorithms for protocol version 2.\n"); 184 fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n"); 185 fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n"); 186 fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n"); 187 fprintf(stderr, " These cause %s to listen for connections on a port, and\n", __progname); 188 fprintf(stderr, " forward them to the other side by connecting to host:port.\n"); 189 fprintf(stderr, " -D port Enable dynamic application-level port forwarding.\n"); 190 fprintf(stderr, " -C Enable compression.\n"); 191 fprintf(stderr, " -N Do not execute a shell or command.\n"); 192 fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n"); 193 fprintf(stderr, " -1 Force protocol version 1.\n"); 194 fprintf(stderr, " -2 Force protocol version 2.\n"); 195 fprintf(stderr, " -4 Use IPv4 only.\n"); 196 fprintf(stderr, " -6 Use IPv6 only.\n"); 197 fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n"); 198 fprintf(stderr, " -s Invoke command (mandatory) as SSH2 subsystem.\n"); 199 fprintf(stderr, " -b addr Local IP address.\n"); 200 exit(1); 201 } 202 203 /* 204 * Connects to the given host using rsh (or prints an error message and exits 205 * if rsh is not available). This function never returns. 206 */ 207 static void 208 rsh_connect(char *host, char *user, Buffer * command) 209 { 210 char *args[10]; 211 int i; 212 213 log("Using rsh. WARNING: Connection will not be encrypted."); 214 /* Build argument list for rsh. */ 215 i = 0; 216 args[i++] = _PATH_RSH; 217 /* host may have to come after user on some systems */ 218 args[i++] = host; 219 if (user) { 220 args[i++] = "-l"; 221 args[i++] = user; 222 } 223 if (buffer_len(command) > 0) { 224 buffer_append(command, "\0", 1); 225 args[i++] = buffer_ptr(command); 226 } 227 args[i++] = NULL; 228 if (debug_flag) { 229 for (i = 0; args[i]; i++) { 230 if (i != 0) 231 fprintf(stderr, " "); 232 fprintf(stderr, "%s", args[i]); 233 } 234 fprintf(stderr, "\n"); 235 } 236 execv(_PATH_RSH, args); 237 perror(_PATH_RSH); 238 exit(1); 239 } 240 241 static int ssh_session(void); 242 static int ssh_session2(void); 243 static void load_public_identity_files(void); 244 245 /* 246 * Main program for the ssh client. 247 */ 248 int 249 main(int ac, char **av) 250 { 251 int i, opt, exit_status, cerr; 252 u_short fwd_port, fwd_host_port; 253 char sfwd_port[6], sfwd_host_port[6]; 254 char *p, *cp, buf[256]; 255 struct stat st; 256 struct passwd *pw; 257 int dummy; 258 uid_t original_effective_uid; 259 260 /* 261 * Save the original real uid. It will be needed later (uid-swapping 262 * may clobber the real uid). 263 */ 264 original_real_uid = getuid(); 265 original_effective_uid = geteuid(); 266 267 /* If we are installed setuid root be careful to not drop core. */ 268 if (original_real_uid != original_effective_uid) { 269 struct rlimit rlim; 270 rlim.rlim_cur = rlim.rlim_max = 0; 271 if (setrlimit(RLIMIT_CORE, &rlim) < 0) 272 fatal("setrlimit failed: %.100s", strerror(errno)); 273 } 274 /* Get user data. */ 275 pw = getpwuid(original_real_uid); 276 if (!pw) { 277 log("You don't exist, go away!"); 278 exit(1); 279 } 280 /* Take a copy of the returned structure. */ 281 pw = pwcopy(pw); 282 283 /* 284 * Use uid-swapping to give up root privileges for the duration of 285 * option processing. We will re-instantiate the rights when we are 286 * ready to create the privileged port, and will permanently drop 287 * them when the port has been created (actually, when the connection 288 * has been made, as we may need to create the port several times). 289 */ 290 temporarily_use_uid(pw); 291 292 /* 293 * Set our umask to something reasonable, as some files are created 294 * with the default umask. This will make them world-readable but 295 * writable only by the owner, which is ok for all files for which we 296 * don't set the modes explicitly. 297 */ 298 umask(022); 299 300 /* Initialize option structure to indicate that no values have been set. */ 301 initialize_options(&options); 302 303 /* Parse command-line arguments. */ 304 host = NULL; 305 306 again: 307 while ((opt = getopt(ac, av, 308 "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVX")) != -1) { 309 switch (opt) { 310 case '1': 311 options.protocol = SSH_PROTO_1; 312 break; 313 case '2': 314 options.protocol = SSH_PROTO_2; 315 break; 316 case '4': 317 IPv4or6 = AF_INET; 318 break; 319 case '6': 320 IPv4or6 = AF_INET6; 321 break; 322 case 'n': 323 stdin_null_flag = 1; 324 break; 325 case 'f': 326 fork_after_authentication_flag = 1; 327 stdin_null_flag = 1; 328 break; 329 case 'x': 330 options.forward_x11 = 0; 331 break; 332 case 'X': 333 options.forward_x11 = 1; 334 break; 335 case 'g': 336 options.gateway_ports = 1; 337 break; 338 case 'P': 339 options.use_privileged_port = 0; 340 break; 341 case 'a': 342 options.forward_agent = 0; 343 break; 344 case 'A': 345 options.forward_agent = 1; 346 break; 347 #ifdef AFS 348 case 'k': 349 options.kerberos_tgt_passing = 0; 350 options.afs_token_passing = 0; 351 break; 352 #endif 353 case 'i': 354 if (stat(optarg, &st) < 0) { 355 fprintf(stderr, "Warning: Identity file %s " 356 "does not exist.\n", optarg); 357 break; 358 } 359 if (options.num_identity_files >= 360 SSH_MAX_IDENTITY_FILES) 361 fatal("Too many identity files specified " 362 "(max %d)", SSH_MAX_IDENTITY_FILES); 363 options.identity_files[options.num_identity_files++] = 364 xstrdup(optarg); 365 break; 366 case 'I': 367 #ifdef SMARTCARD 368 options.smartcard_device = xstrdup(optarg); 369 #else 370 fprintf(stderr, "no support for smartcards.\n"); 371 #endif 372 break; 373 case 't': 374 if (tty_flag) 375 force_tty_flag = 1; 376 tty_flag = 1; 377 break; 378 case 'v': 379 if (0 == debug_flag) { 380 debug_flag = 1; 381 options.log_level = SYSLOG_LEVEL_DEBUG1; 382 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { 383 options.log_level++; 384 break; 385 } else 386 fatal("Too high debugging level."); 387 /* fallthrough */ 388 case 'V': 389 fprintf(stderr, 390 "%s, SSH protocols %d.%d/%d.%d, OpenSSL 0x%8.8lx\n", 391 SSH_VERSION, 392 PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1, 393 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, 394 SSLeay()); 395 if (opt == 'V') 396 exit(0); 397 break; 398 case 'q': 399 options.log_level = SYSLOG_LEVEL_QUIET; 400 break; 401 case 'e': 402 if (optarg[0] == '^' && optarg[2] == 0 && 403 (u_char) optarg[1] >= 64 && 404 (u_char) optarg[1] < 128) 405 options.escape_char = (u_char) optarg[1] & 31; 406 else if (strlen(optarg) == 1) 407 options.escape_char = (u_char) optarg[0]; 408 else if (strcmp(optarg, "none") == 0) 409 options.escape_char = SSH_ESCAPECHAR_NONE; 410 else { 411 fprintf(stderr, "Bad escape character '%s'.\n", 412 optarg); 413 exit(1); 414 } 415 break; 416 case 'c': 417 if (ciphers_valid(optarg)) { 418 /* SSH2 only */ 419 options.ciphers = xstrdup(optarg); 420 options.cipher = SSH_CIPHER_ILLEGAL; 421 } else { 422 /* SSH1 only */ 423 options.cipher = cipher_number(optarg); 424 if (options.cipher == -1) { 425 fprintf(stderr, 426 "Unknown cipher type '%s'\n", 427 optarg); 428 exit(1); 429 } 430 if (options.cipher == SSH_CIPHER_3DES) 431 options.ciphers = "3des-cbc"; 432 else if (options.cipher == SSH_CIPHER_BLOWFISH) 433 options.ciphers = "blowfish-cbc"; 434 else 435 options.ciphers = (char *)-1; 436 } 437 break; 438 case 'm': 439 if (mac_valid(optarg)) 440 options.macs = xstrdup(optarg); 441 else { 442 fprintf(stderr, "Unknown mac type '%s'\n", 443 optarg); 444 exit(1); 445 } 446 break; 447 case 'p': 448 options.port = a2port(optarg); 449 if (options.port == 0) { 450 fprintf(stderr, "Bad port '%s'\n", optarg); 451 exit(1); 452 } 453 break; 454 case 'l': 455 options.user = optarg; 456 break; 457 458 case 'L': 459 case 'R': 460 if (sscanf(optarg, "%5[0-9]:%255[^:]:%5[0-9]", 461 sfwd_port, buf, sfwd_host_port) != 3 && 462 sscanf(optarg, "%5[0-9]/%255[^/]/%5[0-9]", 463 sfwd_port, buf, sfwd_host_port) != 3) { 464 fprintf(stderr, 465 "Bad forwarding specification '%s'\n", 466 optarg); 467 usage(); 468 /* NOTREACHED */ 469 } 470 if ((fwd_port = a2port(sfwd_port)) == 0 || 471 (fwd_host_port = a2port(sfwd_host_port)) == 0) { 472 fprintf(stderr, 473 "Bad forwarding port(s) '%s'\n", optarg); 474 exit(1); 475 } 476 if (opt == 'L') 477 add_local_forward(&options, fwd_port, buf, 478 fwd_host_port); 479 else if (opt == 'R') 480 add_remote_forward(&options, fwd_port, buf, 481 fwd_host_port); 482 break; 483 484 case 'D': 485 fwd_port = a2port(optarg); 486 if (fwd_port == 0) { 487 fprintf(stderr, "Bad dynamic port '%s'\n", 488 optarg); 489 exit(1); 490 } 491 add_local_forward(&options, fwd_port, "socks4", 0); 492 break; 493 494 case 'C': 495 options.compression = 1; 496 break; 497 case 'N': 498 no_shell_flag = 1; 499 no_tty_flag = 1; 500 break; 501 case 'T': 502 no_tty_flag = 1; 503 break; 504 case 'o': 505 dummy = 1; 506 if (process_config_line(&options, host ? host : "", 507 optarg, "command-line", 0, &dummy) != 0) 508 exit(1); 509 break; 510 case 's': 511 subsystem_flag = 1; 512 break; 513 case 'b': 514 options.bind_address = optarg; 515 break; 516 case 'F': 517 config = optarg; 518 break; 519 default: 520 usage(); 521 } 522 } 523 524 ac -= optind; 525 av += optind; 526 527 if (ac > 0 && !host && **av != '-') { 528 if (strchr(*av, '@')) { 529 p = xstrdup(*av); 530 cp = strchr(p, '@'); 531 if (cp == NULL || cp == p) 532 usage(); 533 options.user = p; 534 *cp = '\0'; 535 host = ++cp; 536 } else 537 host = *av; 538 ac--, av++; 539 if (ac > 0) { 540 optind = 0; 541 optreset = 1; 542 goto again; 543 } 544 } 545 546 /* Check that we got a host name. */ 547 if (!host) 548 usage(); 549 550 SSLeay_add_all_algorithms(); 551 ERR_load_crypto_strings(); 552 553 /* Initialize the command to execute on remote host. */ 554 buffer_init(&command); 555 556 /* 557 * Save the command to execute on the remote host in a buffer. There 558 * is no limit on the length of the command, except by the maximum 559 * packet size. Also sets the tty flag if there is no command. 560 */ 561 if (!ac) { 562 /* No command specified - execute shell on a tty. */ 563 tty_flag = 1; 564 if (subsystem_flag) { 565 fprintf(stderr, 566 "You must specify a subsystem to invoke.\n"); 567 usage(); 568 } 569 } else { 570 /* A command has been specified. Store it into the buffer. */ 571 for (i = 0; i < ac; i++) { 572 if (i) 573 buffer_append(&command, " ", 1); 574 buffer_append(&command, av[i], strlen(av[i])); 575 } 576 } 577 578 /* Cannot fork to background if no command. */ 579 if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag) 580 fatal("Cannot fork into background without a command to execute."); 581 582 /* Allocate a tty by default if no command specified. */ 583 if (buffer_len(&command) == 0) 584 tty_flag = 1; 585 586 /* Force no tty*/ 587 if (no_tty_flag) 588 tty_flag = 0; 589 /* Do not allocate a tty if stdin is not a tty. */ 590 if (!isatty(fileno(stdin)) && !force_tty_flag) { 591 if (tty_flag) 592 log("Pseudo-terminal will not be allocated because stdin is not a terminal."); 593 tty_flag = 0; 594 } 595 596 /* 597 * Initialize "log" output. Since we are the client all output 598 * actually goes to stderr. 599 */ 600 log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level, 601 SYSLOG_FACILITY_USER, 1); 602 603 /* 604 * Read per-user configuration file. Ignore the system wide config 605 * file if the user specifies a config file on the command line. 606 */ 607 if (config != NULL) { 608 if (!read_config_file(config, host, &options)) 609 fatal("Can't open user config file %.100s: " 610 "%.100s", config, strerror(errno)); 611 } else { 612 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, 613 _PATH_SSH_USER_CONFFILE); 614 615 /* Read systemwide configuration file. */ 616 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options); 617 (void)read_config_file(buf, host, &options); 618 } 619 620 /* Fill configuration defaults. */ 621 fill_default_options(&options); 622 623 /* reinit */ 624 log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1); 625 626 if (options.user == NULL) 627 options.user = xstrdup(pw->pw_name); 628 629 if (options.hostname != NULL) 630 host = options.hostname; 631 632 /* Disable rhosts authentication if not running as root. */ 633 if (original_effective_uid != 0 || !options.use_privileged_port) { 634 debug("Rhosts Authentication disabled, " 635 "originating port will not be trusted."); 636 options.rhosts_authentication = 0; 637 } 638 /* 639 * If using rsh has been selected, exec it now (without trying 640 * anything else). Note that we must release privileges first. 641 */ 642 if (options.use_rsh) { 643 /* 644 * Restore our superuser privileges. This must be done 645 * before permanently setting the uid. 646 */ 647 restore_uid(); 648 649 /* Switch to the original uid permanently. */ 650 permanently_set_uid(pw); 651 652 /* Execute rsh. */ 653 rsh_connect(host, options.user, &command); 654 fatal("rsh_connect returned"); 655 } 656 /* Restore our superuser privileges. */ 657 restore_uid(); 658 659 /* Open a connection to the remote host. */ 660 661 cerr = ssh_connect(host, &hostaddr, options.port, 662 options.connection_attempts, 663 original_effective_uid != 0 || !options.use_privileged_port, 664 pw, options.proxy_command); 665 666 /* 667 * If we successfully made the connection, load the host private key 668 * in case we will need it later for combined rsa-rhosts 669 * authentication. This must be done before releasing extra 670 * privileges, because the file is only readable by root. 671 */ 672 sensitive_data.nkeys = 0; 673 sensitive_data.keys = NULL; 674 if (!cerr && (options.rhosts_rsa_authentication || 675 options.hostbased_authentication)) { 676 sensitive_data.nkeys = 3; 677 sensitive_data.keys = xmalloc(sensitive_data.nkeys*sizeof(Key)); 678 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1, 679 _PATH_HOST_KEY_FILE, "", NULL); 680 sensitive_data.keys[1] = key_load_private_type(KEY_DSA, 681 _PATH_HOST_DSA_KEY_FILE, "", NULL); 682 sensitive_data.keys[2] = key_load_private_type(KEY_RSA, 683 _PATH_HOST_RSA_KEY_FILE, "", NULL); 684 } 685 /* 686 * Get rid of any extra privileges that we may have. We will no 687 * longer need them. Also, extra privileges could make it very hard 688 * to read identity files and other non-world-readable files from the 689 * user's home directory if it happens to be on a NFS volume where 690 * root is mapped to nobody. 691 */ 692 693 /* 694 * Note that some legacy systems need to postpone the following call 695 * to permanently_set_uid() until the private hostkey is destroyed 696 * with RSA_free(). Otherwise the calling user could ptrace() the 697 * process, read the private hostkey and impersonate the host. 698 * OpenBSD does not allow ptracing of setuid processes. 699 */ 700 permanently_set_uid(pw); 701 702 /* 703 * Now that we are back to our own permissions, create ~/.ssh 704 * directory if it doesn\'t already exist. 705 */ 706 snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR); 707 if (stat(buf, &st) < 0) 708 if (mkdir(buf, 0700) < 0) 709 error("Could not create directory '%.200s'.", buf); 710 711 /* Check if the connection failed, and try "rsh" if appropriate. */ 712 if (cerr) { 713 if (!options.fallback_to_rsh) 714 exit(1); 715 if (options.port != 0) 716 log("Secure connection to %.100s on port %hu refused; " 717 "reverting to insecure method", 718 host, options.port); 719 else 720 log("Secure connection to %.100s refused; " 721 "reverting to insecure method.", host); 722 723 rsh_connect(host, options.user, &command); 724 fatal("rsh_connect returned"); 725 } 726 /* load options.identity_files */ 727 load_public_identity_files(); 728 729 /* Expand ~ in known host file names. */ 730 /* XXX mem-leaks: */ 731 options.system_hostfile = 732 tilde_expand_filename(options.system_hostfile, original_real_uid); 733 options.user_hostfile = 734 tilde_expand_filename(options.user_hostfile, original_real_uid); 735 options.system_hostfile2 = 736 tilde_expand_filename(options.system_hostfile2, original_real_uid); 737 options.user_hostfile2 = 738 tilde_expand_filename(options.user_hostfile2, original_real_uid); 739 740 /* Log into the remote system. This never returns if the login fails. */ 741 ssh_login(sensitive_data.keys, sensitive_data.nkeys, 742 host, (struct sockaddr *)&hostaddr, pw); 743 744 /* We no longer need the private host keys. Clear them now. */ 745 if (sensitive_data.nkeys != 0) { 746 for (i = 0; i < sensitive_data.nkeys; i++) { 747 if (sensitive_data.keys[i] != NULL) { 748 /* Destroys contents safely */ 749 debug3("clear hostkey %d", i); 750 key_free(sensitive_data.keys[i]); 751 sensitive_data.keys[i] = NULL; 752 } 753 } 754 xfree(sensitive_data.keys); 755 } 756 for (i = 0; i < options.num_identity_files; i++) { 757 if (options.identity_files[i]) { 758 xfree(options.identity_files[i]); 759 options.identity_files[i] = NULL; 760 } 761 if (options.identity_keys[i]) { 762 key_free(options.identity_keys[i]); 763 options.identity_keys[i] = NULL; 764 } 765 } 766 767 exit_status = compat20 ? ssh_session2() : ssh_session(); 768 packet_close(); 769 return exit_status; 770 } 771 772 static void 773 x11_get_proto(char *proto, int proto_len, char *data, int data_len) 774 { 775 char line[512]; 776 FILE *f; 777 int got_data = 0, i; 778 779 if (options.xauth_location) { 780 /* Try to get Xauthority information for the display. */ 781 snprintf(line, sizeof line, "%.100s list %.200s 2>" _PATH_DEVNULL, 782 options.xauth_location, getenv("DISPLAY")); 783 f = popen(line, "r"); 784 if (f && fgets(line, sizeof(line), f) && 785 sscanf(line, "%*s %s %s", proto, data) == 2) 786 got_data = 1; 787 if (f) 788 pclose(f); 789 } 790 /* 791 * If we didn't get authentication data, just make up some 792 * data. The forwarding code will check the validity of the 793 * response anyway, and substitute this data. The X11 794 * server, however, will ignore this fake data and use 795 * whatever authentication mechanisms it was using otherwise 796 * for the local connection. 797 */ 798 if (!got_data) { 799 u_int32_t rand = 0; 800 801 strlcpy(proto, "MIT-MAGIC-COOKIE-1", proto_len); 802 for (i = 0; i < 16; i++) { 803 if (i % 4 == 0) 804 rand = arc4random(); 805 snprintf(data + 2 * i, data_len - 2 * i, "%02x", rand & 0xff); 806 rand >>= 8; 807 } 808 } 809 } 810 811 static void 812 ssh_init_forwarding(void) 813 { 814 int success = 0; 815 int i; 816 817 /* Initiate local TCP/IP port forwardings. */ 818 for (i = 0; i < options.num_local_forwards; i++) { 819 debug("Connections to local port %d forwarded to remote address %.200s:%d", 820 options.local_forwards[i].port, 821 options.local_forwards[i].host, 822 options.local_forwards[i].host_port); 823 success += channel_request_local_forwarding( 824 options.local_forwards[i].port, 825 options.local_forwards[i].host, 826 options.local_forwards[i].host_port, 827 options.gateway_ports); 828 } 829 if (i > 0 && success == 0) 830 error("Could not request local forwarding."); 831 832 /* Initiate remote TCP/IP port forwardings. */ 833 for (i = 0; i < options.num_remote_forwards; i++) { 834 debug("Connections to remote port %d forwarded to local address %.200s:%d", 835 options.remote_forwards[i].port, 836 options.remote_forwards[i].host, 837 options.remote_forwards[i].host_port); 838 channel_request_remote_forwarding( 839 options.remote_forwards[i].port, 840 options.remote_forwards[i].host, 841 options.remote_forwards[i].host_port); 842 } 843 } 844 845 static void 846 check_agent_present(void) 847 { 848 if (options.forward_agent) { 849 /* Clear agent forwarding if we don\'t have an agent. */ 850 int authfd = ssh_get_authentication_socket(); 851 if (authfd < 0) 852 options.forward_agent = 0; 853 else 854 ssh_close_authentication_socket(authfd); 855 } 856 } 857 858 static int 859 ssh_session(void) 860 { 861 int type; 862 int plen; 863 int interactive = 0; 864 int have_tty = 0; 865 struct winsize ws; 866 char *cp; 867 868 /* Enable compression if requested. */ 869 if (options.compression) { 870 debug("Requesting compression at level %d.", options.compression_level); 871 872 if (options.compression_level < 1 || options.compression_level > 9) 873 fatal("Compression level must be from 1 (fast) to 9 (slow, best)."); 874 875 /* Send the request. */ 876 packet_start(SSH_CMSG_REQUEST_COMPRESSION); 877 packet_put_int(options.compression_level); 878 packet_send(); 879 packet_write_wait(); 880 type = packet_read(&plen); 881 if (type == SSH_SMSG_SUCCESS) 882 packet_start_compression(options.compression_level); 883 else if (type == SSH_SMSG_FAILURE) 884 log("Warning: Remote host refused compression."); 885 else 886 packet_disconnect("Protocol error waiting for compression response."); 887 } 888 /* Allocate a pseudo tty if appropriate. */ 889 if (tty_flag) { 890 debug("Requesting pty."); 891 892 /* Start the packet. */ 893 packet_start(SSH_CMSG_REQUEST_PTY); 894 895 /* Store TERM in the packet. There is no limit on the 896 length of the string. */ 897 cp = getenv("TERM"); 898 if (!cp) 899 cp = ""; 900 packet_put_cstring(cp); 901 902 /* Store window size in the packet. */ 903 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) 904 memset(&ws, 0, sizeof(ws)); 905 packet_put_int(ws.ws_row); 906 packet_put_int(ws.ws_col); 907 packet_put_int(ws.ws_xpixel); 908 packet_put_int(ws.ws_ypixel); 909 910 /* Store tty modes in the packet. */ 911 tty_make_modes(fileno(stdin), NULL); 912 913 /* Send the packet, and wait for it to leave. */ 914 packet_send(); 915 packet_write_wait(); 916 917 /* Read response from the server. */ 918 type = packet_read(&plen); 919 if (type == SSH_SMSG_SUCCESS) { 920 interactive = 1; 921 have_tty = 1; 922 } else if (type == SSH_SMSG_FAILURE) 923 log("Warning: Remote host failed or refused to allocate a pseudo tty."); 924 else 925 packet_disconnect("Protocol error waiting for pty request response."); 926 } 927 /* Request X11 forwarding if enabled and DISPLAY is set. */ 928 if (options.forward_x11 && getenv("DISPLAY") != NULL) { 929 char proto[512], data[512]; 930 /* Get reasonable local authentication information. */ 931 x11_get_proto(proto, sizeof proto, data, sizeof data); 932 /* Request forwarding with authentication spoofing. */ 933 debug("Requesting X11 forwarding with authentication spoofing."); 934 x11_request_forwarding_with_spoofing(0, proto, data); 935 936 /* Read response from the server. */ 937 type = packet_read(&plen); 938 if (type == SSH_SMSG_SUCCESS) { 939 interactive = 1; 940 } else if (type == SSH_SMSG_FAILURE) { 941 log("Warning: Remote host denied X11 forwarding."); 942 } else { 943 packet_disconnect("Protocol error waiting for X11 forwarding"); 944 } 945 } 946 /* Tell the packet module whether this is an interactive session. */ 947 packet_set_interactive(interactive); 948 949 /* Request authentication agent forwarding if appropriate. */ 950 check_agent_present(); 951 952 if (options.forward_agent) { 953 debug("Requesting authentication agent forwarding."); 954 auth_request_forwarding(); 955 956 /* Read response from the server. */ 957 type = packet_read(&plen); 958 packet_integrity_check(plen, 0, type); 959 if (type != SSH_SMSG_SUCCESS) 960 log("Warning: Remote host denied authentication agent forwarding."); 961 } 962 963 /* Initiate port forwardings. */ 964 ssh_init_forwarding(); 965 966 /* If requested, let ssh continue in the background. */ 967 if (fork_after_authentication_flag) 968 if (daemon(1, 1) < 0) 969 fatal("daemon() failed: %.200s", strerror(errno)); 970 971 /* 972 * If a command was specified on the command line, execute the 973 * command now. Otherwise request the server to start a shell. 974 */ 975 if (buffer_len(&command) > 0) { 976 int len = buffer_len(&command); 977 if (len > 900) 978 len = 900; 979 debug("Sending command: %.*s", len, buffer_ptr(&command)); 980 packet_start(SSH_CMSG_EXEC_CMD); 981 packet_put_string(buffer_ptr(&command), buffer_len(&command)); 982 packet_send(); 983 packet_write_wait(); 984 } else { 985 debug("Requesting shell."); 986 packet_start(SSH_CMSG_EXEC_SHELL); 987 packet_send(); 988 packet_write_wait(); 989 } 990 991 /* Enter the interactive session. */ 992 return client_loop(have_tty, tty_flag ? 993 options.escape_char : SSH_ESCAPECHAR_NONE, 0); 994 } 995 996 static void 997 client_subsystem_reply(int type, int plen, void *ctxt) 998 { 999 int id, len; 1000 1001 id = packet_get_int(); 1002 len = buffer_len(&command); 1003 if (len > 900) 1004 len = 900; 1005 packet_done(); 1006 if (type == SSH2_MSG_CHANNEL_FAILURE) 1007 fatal("Request for subsystem '%.*s' failed on channel %d", 1008 len, buffer_ptr(&command), id); 1009 } 1010 1011 /* request pty/x11/agent/tcpfwd/shell for channel */ 1012 static void 1013 ssh_session2_setup(int id, void *arg) 1014 { 1015 int len; 1016 int interactive = 0; 1017 struct termios tio; 1018 1019 debug("ssh_session2_setup: id %d", id); 1020 1021 if (tty_flag) { 1022 struct winsize ws; 1023 char *cp; 1024 cp = getenv("TERM"); 1025 if (!cp) 1026 cp = ""; 1027 /* Store window size in the packet. */ 1028 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) 1029 memset(&ws, 0, sizeof(ws)); 1030 1031 channel_request_start(id, "pty-req", 0); 1032 packet_put_cstring(cp); 1033 packet_put_int(ws.ws_col); 1034 packet_put_int(ws.ws_row); 1035 packet_put_int(ws.ws_xpixel); 1036 packet_put_int(ws.ws_ypixel); 1037 tio = get_saved_tio(); 1038 tty_make_modes(/*ignored*/ 0, &tio); 1039 packet_send(); 1040 interactive = 1; 1041 /* XXX wait for reply */ 1042 } 1043 if (options.forward_x11 && 1044 getenv("DISPLAY") != NULL) { 1045 char proto[512], data[512]; 1046 /* Get reasonable local authentication information. */ 1047 x11_get_proto(proto, sizeof proto, data, sizeof data); 1048 /* Request forwarding with authentication spoofing. */ 1049 debug("Requesting X11 forwarding with authentication spoofing."); 1050 x11_request_forwarding_with_spoofing(id, proto, data); 1051 interactive = 1; 1052 /* XXX wait for reply */ 1053 } 1054 1055 check_agent_present(); 1056 if (options.forward_agent) { 1057 debug("Requesting authentication agent forwarding."); 1058 channel_request_start(id, "auth-agent-req@openssh.com", 0); 1059 packet_send(); 1060 } 1061 1062 len = buffer_len(&command); 1063 if (len > 0) { 1064 if (len > 900) 1065 len = 900; 1066 if (subsystem_flag) { 1067 debug("Sending subsystem: %.*s", len, buffer_ptr(&command)); 1068 channel_request_start(id, "subsystem", /*want reply*/ 1); 1069 /* register callback for reply */ 1070 /* XXX we asume that client_loop has already been called */ 1071 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply); 1072 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply); 1073 } else { 1074 debug("Sending command: %.*s", len, buffer_ptr(&command)); 1075 channel_request_start(id, "exec", 0); 1076 } 1077 packet_put_string(buffer_ptr(&command), buffer_len(&command)); 1078 packet_send(); 1079 } else { 1080 channel_request(id, "shell", 0); 1081 } 1082 /* channel_callback(id, SSH2_MSG_OPEN_CONFIGMATION, client_init, 0); */ 1083 1084 /* register different callback, etc. XXX */ 1085 packet_set_interactive(interactive); 1086 } 1087 1088 /* open new channel for a session */ 1089 static int 1090 ssh_session2_open(void) 1091 { 1092 Channel *c; 1093 int window, packetmax, in, out, err; 1094 1095 if (stdin_null_flag) { 1096 in = open(_PATH_DEVNULL, O_RDONLY); 1097 } else { 1098 in = dup(STDIN_FILENO); 1099 } 1100 out = dup(STDOUT_FILENO); 1101 err = dup(STDERR_FILENO); 1102 1103 if (in < 0 || out < 0 || err < 0) 1104 fatal("dup() in/out/err failed"); 1105 1106 /* enable nonblocking unless tty */ 1107 if (!isatty(in)) 1108 set_nonblock(in); 1109 if (!isatty(out)) 1110 set_nonblock(out); 1111 if (!isatty(err)) 1112 set_nonblock(err); 1113 1114 window = CHAN_SES_WINDOW_DEFAULT; 1115 packetmax = CHAN_SES_PACKET_DEFAULT; 1116 if (!tty_flag) { 1117 window *= 2; 1118 packetmax *=2; 1119 } 1120 c = channel_new( 1121 "session", SSH_CHANNEL_OPENING, in, out, err, 1122 window, packetmax, CHAN_EXTENDED_WRITE, 1123 xstrdup("client-session"), /*nonblock*/0); 1124 if (c == NULL) 1125 fatal("ssh_session2_open: channel_new failed"); 1126 1127 debug3("ssh_session2_open: channel_new: %d", c->self); 1128 1129 channel_send_open(c->self); 1130 if (!no_shell_flag) 1131 channel_register_callback(c->self, 1132 SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, 1133 ssh_session2_setup, (void *)0); 1134 1135 return c->self; 1136 } 1137 1138 static int 1139 ssh_session2(void) 1140 { 1141 int id = -1; 1142 1143 /* XXX should be pre-session */ 1144 ssh_init_forwarding(); 1145 1146 if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN)) 1147 id = ssh_session2_open(); 1148 1149 /* If requested, let ssh continue in the background. */ 1150 if (fork_after_authentication_flag) 1151 if (daemon(1, 1) < 0) 1152 fatal("daemon() failed: %.200s", strerror(errno)); 1153 1154 return client_loop(tty_flag, tty_flag ? 1155 options.escape_char : SSH_ESCAPECHAR_NONE, id); 1156 } 1157 1158 static void 1159 load_public_identity_files(void) 1160 { 1161 char *filename; 1162 Key *public; 1163 int i = 0; 1164 1165 #ifdef SMARTCARD 1166 if (options.smartcard_device != NULL && 1167 options.num_identity_files + 1 < SSH_MAX_IDENTITY_FILES && 1168 (public = sc_get_key(options.smartcard_device)) != NULL ) { 1169 Key *new; 1170 1171 if (options.num_identity_files + 2 > SSH_MAX_IDENTITY_FILES) 1172 options.num_identity_files = SSH_MAX_IDENTITY_FILES - 2; 1173 memmove(&options.identity_files[2], &options.identity_files[0], 1174 sizeof(char *) * options.num_identity_files); 1175 options.num_identity_files += 2; 1176 i = 2; 1177 1178 /* XXX ssh1 vs ssh2 */ 1179 new = key_new(KEY_RSA); 1180 new->flags = KEY_FLAG_EXT; 1181 BN_copy(new->rsa->n, public->rsa->n); 1182 BN_copy(new->rsa->e, public->rsa->e); 1183 RSA_set_method(new->rsa, sc_get_engine()); 1184 options.identity_keys[0] = new; 1185 options.identity_files[0] = xstrdup("smartcard rsa key");; 1186 1187 new = key_new(KEY_RSA1); 1188 new->flags = KEY_FLAG_EXT; 1189 BN_copy(new->rsa->n, public->rsa->n); 1190 BN_copy(new->rsa->e, public->rsa->e); 1191 RSA_set_method(new->rsa, sc_get_engine()); 1192 options.identity_keys[1] = new; 1193 options.identity_files[1] = xstrdup("smartcard rsa1 key"); 1194 1195 key_free(public); 1196 } 1197 #endif /* SMARTCARD */ 1198 for (; i < options.num_identity_files; i++) { 1199 filename = tilde_expand_filename(options.identity_files[i], 1200 original_real_uid); 1201 public = key_load_public(filename, NULL); 1202 debug("identity file %s type %d", filename, 1203 public ? public->type : -1); 1204 xfree(options.identity_files[i]); 1205 options.identity_files[i] = filename; 1206 options.identity_keys[i] = public; 1207 } 1208 } 1209