ssh.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * Ssh client program.  This program can be used to log into a remote machine.
   6  * The software supports strong authentication, encryption, and forwarding
   7  * of X11, TCP/IP, and authentication connections.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  16  * Copyright (c) 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  17  *
  18  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  19  * in Canada (German citizen).
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43 RCSID("$OpenBSD: ssh.c,v 1.200 2003/08/13 09:07:10 markus Exp $");
  44
  45 #include <openssl/evp.h>
  46 #include <openssl/err.h>
  47
  48 #include "ssh.h"
  49 #include "ssh1.h"
  50 #include "ssh2.h"
  51 #include "compat.h"
  52 #include "cipher.h"
  53 #include "xmalloc.h"
  54 #include "packet.h"
  55 #include "buffer.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 "scard.h"
  74 #endif
  75
  76 #ifdef HAVE___PROGNAME
  77 extern char *__progname;
  78 #else
  79 char *__progname;
  80 #endif
  81
  82 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
  83 int debug_flag = 0;
  84
  85 /* Flag indicating whether a tty should be allocated */
  86 int tty_flag = 0;
  87 int no_tty_flag = 0;
  88 int force_tty_flag = 0;
  89
  90 /* don't exec a shell */
  91 int no_shell_flag = 0;
  92
  93 /*
  94  * Flag indicating that nothing should be read from stdin.  This can be set
  95  * on the command line.
  96  */
  97 int stdin_null_flag = 0;
  98
  99 /*
 100  * Flag indicating that ssh should fork after authentication.  This is useful
 101  * so that the passphrase can be entered manually, and then ssh goes to the
 102  * background.
 103  */
 104 int fork_after_authentication_flag = 0;
 105
 106 /*
 107  * General data structure for command line options and options configurable
 108  * in configuration files.  See readconf.h.
 109  */
 110 Options options;
 111
 112 /* optional user configfile */
 113 char *config = NULL;
 114
 115 /*
 116  * Name of the host we are connecting to.  This is the name given on the
 117  * command line, or the HostName specified for the user-supplied name in a
 118  * configuration file.
 119  */
 120 char *host;
 121
 122 /* socket address the host resolves to */
 123 struct sockaddr_storage hostaddr;
 124
 125 /* Private host keys. */
 126 Sensitive sensitive_data;
 127
 128 /* Original real UID. */
 129 uid_t original_real_uid;
 130 uid_t original_effective_uid;
 131
 132 /* command to be executed */
 133 Buffer command;
 134
 135 /* Should we execute a command or invoke a subsystem? */
 136 int subsystem_flag = 0;
 137
 138 /* # of replies received for global requests */
 139 static int client_global_request_id = 0;
 140
 141 /* pid of proxycommand child process */
 142 pid_t proxy_command_pid = 0;
 143
 144 /* Prints a help message to the user.  This function never returns. */
 145
 146 static void
 147 usage(void)
 148 {
 149         fprintf(stderr, "Usage: %s [options] host [command]\n", __progname);
 150         fprintf(stderr, "Options:\n");
 151         fprintf(stderr, "  -l user     Log in using this user name.\n");
 152         fprintf(stderr, "  -n          Redirect input from " _PATH_DEVNULL ".\n");
 153         fprintf(stderr, "  -F config   Config file (default: ~/%s).\n",
 154              _PATH_SSH_USER_CONFFILE);
 155         fprintf(stderr, "  -A          Enable authentication agent forwarding.\n");
 156         fprintf(stderr, "  -a          Disable authentication agent forwarding (default).\n");
 157         fprintf(stderr, "  -k          Disable Kerberos ticket forwarding.\n");
 158         fprintf(stderr, "  -X          Enable X11 connection forwarding.\n");
 159         fprintf(stderr, "  -x          Disable X11 connection forwarding (default).\n");
 160         fprintf(stderr, "  -i file     Identity for public key authentication "
 161             "(default: ~/.ssh/identity)\n");
 162 #ifdef SMARTCARD
 163         fprintf(stderr, "  -I reader   Set smartcard reader.\n");
 164 #endif
 165         fprintf(stderr, "  -t          Tty; allocate a tty even if command is given.\n");
 166         fprintf(stderr, "  -T          Do not allocate a tty.\n");
 167         fprintf(stderr, "  -v          Verbose; display verbose debugging messages.\n");
 168         fprintf(stderr, "              Multiple -v increases verbosity.\n");
 169         fprintf(stderr, "  -V          Display version number only.\n");
 170         fprintf(stderr, "  -q          Quiet; don't display any warning messages.\n");
 171         fprintf(stderr, "  -f          Fork into background after authentication.\n");
 172         fprintf(stderr, "  -e char     Set escape character; ``none'' = disable (default: ~).\n");
 173
 174         fprintf(stderr, "  -c cipher   Select encryption algorithm\n");
 175         fprintf(stderr, "  -m macs     Specify MAC algorithms for protocol version 2.\n");
 176         fprintf(stderr, "  -p port     Connect to this port.  Server must be on the same port.\n");
 177         fprintf(stderr, "  -L listen-port:host:port   Forward local port to remote address\n");
 178         fprintf(stderr, "  -R listen-port:host:port   Forward remote port to local address\n");
 179         fprintf(stderr, "              These cause %s to listen for connections on a port, and\n", __progname);
 180         fprintf(stderr, "              forward them to the other side by connecting to host:port.\n");
 181         fprintf(stderr, "  -D port     Enable dynamic application-level port forwarding.\n");
 182         fprintf(stderr, "  -C          Enable compression.\n");
 183         fprintf(stderr, "  -N          Do not execute a shell or command.\n");
 184         fprintf(stderr, "  -g          Allow remote hosts to connect to forwarded ports.\n");
 185         fprintf(stderr, "  -1          Force protocol version 1.\n");
 186         fprintf(stderr, "  -2          Force protocol version 2.\n");
 187         fprintf(stderr, "  -4          Use IPv4 only.\n");
 188         fprintf(stderr, "  -6          Use IPv6 only.\n");
 189         fprintf(stderr, "  -o 'option' Process the option as if it was read from a configuration file.\n");
 190         fprintf(stderr, "  -s          Invoke command (mandatory) as SSH2 subsystem.\n");
 191         fprintf(stderr, "  -b addr     Local IP address.\n");
 192         exit(1);
 193 }
 194
 195 static int ssh_session(void);
 196 static int ssh_session2(void);
 197 static void load_public_identity_files(void);
 198
 199 /*
 200  * Main program for the ssh client.
 201  */
 202 int
 203 main(int ac, char **av)
 204 {
 205         int i, opt, exit_status;
 206         u_short fwd_port, fwd_host_port;
 207         char sfwd_port[6], sfwd_host_port[6];
 208         char *p, *cp, buf[256];
 209         struct stat st;
 210         struct passwd *pw;
 211         int dummy;
 212         extern int optind, optreset;
 213         extern char *optarg;
 214
 215         __progname = get_progname(av[0]);
 216         init_rng();
 217
 218         /*
 219          * Save the original real uid.  It will be needed later (uid-swapping
 220          * may clobber the real uid).
 221          */
 222         original_real_uid = getuid();
 223         original_effective_uid = geteuid();
 224
 225         /*
 226          * Use uid-swapping to give up root privileges for the duration of
 227          * option processing.  We will re-instantiate the rights when we are
 228          * ready to create the privileged port, and will permanently drop
 229          * them when the port has been created (actually, when the connection
 230          * has been made, as we may need to create the port several times).
 231          */
 232         PRIV_END;
 233
 234 #ifdef HAVE_SETRLIMIT
 235         /* If we are installed setuid root be careful to not drop core. */
 236         if (original_real_uid != original_effective_uid) {
 237                 struct rlimit rlim;
 238                 rlim.rlim_cur = rlim.rlim_max = 0;
 239                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 240                         fatal("setrlimit failed: %.100s", strerror(errno));
 241         }
 242 #endif
 243         /* Get user data. */
 244         pw = getpwuid(original_real_uid);
 245         if (!pw) {
 246                 logit("You don't exist, go away!");
 247                 exit(1);
 248         }
 249         /* Take a copy of the returned structure. */
 250         pw = pwcopy(pw);
 251
 252         /*
 253          * Set our umask to something reasonable, as some files are created
 254          * with the default umask.  This will make them world-readable but
 255          * writable only by the owner, which is ok for all files for which we
 256          * don't set the modes explicitly.
 257          */
 258         umask(022);
 259
 260         /* Initialize option structure to indicate that no values have been set. */
 261         initialize_options(&options);
 262
 263         /* Parse command-line arguments. */
 264         host = NULL;
 265
 266 again:
 267         while ((opt = getopt(ac, av,
 268             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVX")) != -1) {
 269                 switch (opt) {
 270                 case '1':
 271                         options.protocol = SSH_PROTO_1;
 272                         break;
 273                 case '2':
 274                         options.protocol = SSH_PROTO_2;
 275                         break;
 276                 case '4':
 277                         options.address_family = AF_INET;
 278                         break;
 279                 case '6':
 280                         options.address_family = AF_INET6;
 281                         break;
 282                 case 'n':
 283                         stdin_null_flag = 1;
 284                         break;
 285                 case 'f':
 286                         fork_after_authentication_flag = 1;
 287                         stdin_null_flag = 1;
 288                         break;
 289                 case 'x':
 290                         options.forward_x11 = 0;
 291                         break;
 292                 case 'X':
 293                         options.forward_x11 = 1;
 294                         break;
 295                 case 'g':
 296                         options.gateway_ports = 1;
 297                         break;
 298                 case 'P':       /* deprecated */
 299                         options.use_privileged_port = 0;
 300                         break;
 301                 case 'a':
 302                         options.forward_agent = 0;
 303                         break;
 304                 case 'A':
 305                         options.forward_agent = 1;
 306                         break;
 307                 case 'k':
 308                         options.kerberos_tgt_passing = 0;
 309                         break;
 310                 case 'i':
 311                         if (stat(optarg, &st) < 0) {
 312                                 fprintf(stderr, "Warning: Identity file %s "
 313                                     "does not exist.\n", optarg);
 314                                 break;
 315                         }
 316                         if (options.num_identity_files >=
 317                             SSH_MAX_IDENTITY_FILES)
 318                                 fatal("Too many identity files specified "
 319                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 320                         options.identity_files[options.num_identity_files++] =
 321                             xstrdup(optarg);
 322                         break;
 323                 case 'I':
 324 #ifdef SMARTCARD
 325                         options.smartcard_device = xstrdup(optarg);
 326 #else
 327                         fprintf(stderr, "no support for smartcards.\n");
 328 #endif
 329                         break;
 330                 case 't':
 331                         if (tty_flag)
 332                                 force_tty_flag = 1;
 333                         tty_flag = 1;
 334                         break;
 335                 case 'v':
 336                         if (debug_flag == 0) {
 337                                 debug_flag = 1;
 338                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 339                         } else {
 340                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 341                                         options.log_level++;
 342                                 break;
 343                         }
 344                         /* fallthrough */
 345                 case 'V':
 346                         fprintf(stderr,
 347                             "%s, SSH protocols %d.%d/%d.%d, %s\n",
 348                             SSH_VERSION,
 349                             PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
 350                             PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
 351                             SSLeay_version(SSLEAY_VERSION));
 352                         if (opt == 'V')
 353                                 exit(0);
 354                         break;
 355                 case 'q':
 356                         options.log_level = SYSLOG_LEVEL_QUIET;
 357                         break;
 358                 case 'e':
 359                         if (optarg[0] == '^' && optarg[2] == 0 &&
 360                             (u_char) optarg[1] >= 64 &&
 361                             (u_char) optarg[1] < 128)
 362                                 options.escape_char = (u_char) optarg[1] & 31;
 363                         else if (strlen(optarg) == 1)
 364                                 options.escape_char = (u_char) optarg[0];
 365                         else if (strcmp(optarg, "none") == 0)
 366                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 367                         else {
 368                                 fprintf(stderr, "Bad escape character '%s'.\n",
 369                                     optarg);
 370                                 exit(1);
 371                         }
 372                         break;
 373                 case 'c':
 374                         if (ciphers_valid(optarg)) {
 375                                 /* SSH2 only */
 376                                 options.ciphers = xstrdup(optarg);
 377                                 options.cipher = SSH_CIPHER_ILLEGAL;
 378                         } else {
 379                                 /* SSH1 only */
 380                                 options.cipher = cipher_number(optarg);
 381                                 if (options.cipher == -1) {
 382                                         fprintf(stderr,
 383                                             "Unknown cipher type '%s'\n",
 384                                             optarg);
 385                                         exit(1);
 386                                 }
 387                                 if (options.cipher == SSH_CIPHER_3DES)
 388                                         options.ciphers = "3des-cbc";
 389                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 390                                         options.ciphers = "blowfish-cbc";
 391                                 else
 392                                         options.ciphers = (char *)-1;
 393                         }
 394                         break;
 395                 case 'm':
 396                         if (mac_valid(optarg))
 397                                 options.macs = xstrdup(optarg);
 398                         else {
 399                                 fprintf(stderr, "Unknown mac type '%s'\n",
 400                                     optarg);
 401                                 exit(1);
 402                         }
 403                         break;
 404                 case 'p':
 405                         options.port = a2port(optarg);
 406                         if (options.port == 0) {
 407                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 408                                 exit(1);
 409                         }
 410                         break;
 411                 case 'l':
 412                         options.user = optarg;
 413                         break;
 414
 415                 case 'L':
 416                 case 'R':
 417                         if (sscanf(optarg, "%5[0123456789]:%255[^:]:%5[0123456789]",
 418                             sfwd_port, buf, sfwd_host_port) != 3 &&
 419                             sscanf(optarg, "%5[0123456789]/%255[^/]/%5[0123456789]",
 420                             sfwd_port, buf, sfwd_host_port) != 3) {
 421                                 fprintf(stderr,
 422                                     "Bad forwarding specification '%s'\n",
 423                                     optarg);
 424                                 usage();
 425                                 /* NOTREACHED */
 426                         }
 427                         if ((fwd_port = a2port(sfwd_port)) == 0 ||
 428                             (fwd_host_port = a2port(sfwd_host_port)) == 0) {
 429                                 fprintf(stderr,
 430                                     "Bad forwarding port(s) '%s'\n", optarg);
 431                                 exit(1);
 432                         }
 433                         if (opt == 'L')
 434                                 add_local_forward(&options, fwd_port, buf,
 435                                     fwd_host_port);
 436                         else if (opt == 'R')
 437                                 add_remote_forward(&options, fwd_port, buf,
 438                                     fwd_host_port);
 439                         break;
 440
 441                 case 'D':
 442                         fwd_port = a2port(optarg);
 443                         if (fwd_port == 0) {
 444                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 445                                     optarg);
 446                                 exit(1);
 447                         }
 448                         add_local_forward(&options, fwd_port, "socks", 0);
 449                         break;
 450
 451                 case 'C':
 452                         options.compression = 1;
 453                         break;
 454                 case 'N':
 455                         no_shell_flag = 1;
 456                         no_tty_flag = 1;
 457                         break;
 458                 case 'T':
 459                         no_tty_flag = 1;
 460                         break;
 461                 case 'o':
 462                         dummy = 1;
 463                         if (process_config_line(&options, host ? host : "",
 464                             optarg, "command-line", 0, &dummy) != 0)
 465                                 exit(1);
 466                         break;
 467                 case 's':
 468                         subsystem_flag = 1;
 469                         break;
 470                 case 'b':
 471                         options.bind_address = optarg;
 472                         break;
 473                 case 'F':
 474                         config = optarg;
 475                         break;
 476                 default:
 477                         usage();
 478                 }
 479         }
 480
 481         ac -= optind;
 482         av += optind;
 483
 484         if (ac > 0 && !host && **av != '-') {
 485                 if (strrchr(*av, '@')) {
 486                         p = xstrdup(*av);
 487                         cp = strrchr(p, '@');
 488                         if (cp == NULL || cp == p)
 489                                 usage();
 490                         options.user = p;
 491                         *cp = '\0';
 492                         host = ++cp;
 493                 } else
 494                         host = *av;
 495                 if (ac > 1) {
 496                         optind = optreset = 1;
 497                         goto again;
 498                 }
 499                 ac--, av++;
 500         }
 501
 502         /* Check that we got a host name. */
 503         if (!host)
 504                 usage();
 505
 506         SSLeay_add_all_algorithms();
 507         ERR_load_crypto_strings();
 508
 509         /* Initialize the command to execute on remote host. */
 510         buffer_init(&command);
 511
 512         /*
 513          * Save the command to execute on the remote host in a buffer. There
 514          * is no limit on the length of the command, except by the maximum
 515          * packet size.  Also sets the tty flag if there is no command.
 516          */
 517         if (!ac) {
 518                 /* No command specified - execute shell on a tty. */
 519                 tty_flag = 1;
 520                 if (subsystem_flag) {
 521                         fprintf(stderr,
 522                             "You must specify a subsystem to invoke.\n");
 523                         usage();
 524                 }
 525         } else {
 526                 /* A command has been specified.  Store it into the buffer. */
 527                 for (i = 0; i < ac; i++) {
 528                         if (i)
 529                                 buffer_append(&command, " ", 1);
 530                         buffer_append(&command, av[i], strlen(av[i]));
 531                 }
 532         }
 533
 534         /* Cannot fork to background if no command. */
 535         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 536                 fatal("Cannot fork into background without a command to execute.");
 537
 538         /* Allocate a tty by default if no command specified. */
 539         if (buffer_len(&command) == 0)
 540                 tty_flag = 1;
 541
 542         /* Force no tty */
 543         if (no_tty_flag)
 544                 tty_flag = 0;
 545         /* Do not allocate a tty if stdin is not a tty. */
 546         if (!isatty(fileno(stdin)) && !force_tty_flag) {
 547                 if (tty_flag)
 548                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 549                 tty_flag = 0;
 550         }
 551
 552         /*
 553          * Initialize "log" output.  Since we are the client all output
 554          * actually goes to stderr.
 555          */
 556         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 557             SYSLOG_FACILITY_USER, 1);
 558
 559         /*
 560          * Read per-user configuration file.  Ignore the system wide config
 561          * file if the user specifies a config file on the command line.
 562          */
 563         if (config != NULL) {
 564                 if (!read_config_file(config, host, &options))
 565                         fatal("Can't open user config file %.100s: "
 566                             "%.100s", config, strerror(errno));
 567         } else  {
 568                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 569                     _PATH_SSH_USER_CONFFILE);
 570                 (void)read_config_file(buf, host, &options);
 571
 572                 /* Read systemwide configuration file after use config. */
 573                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
 574         }
 575
 576         /* Fill configuration defaults. */
 577         fill_default_options(&options);
 578
 579         channel_set_af(options.address_family);
 580
 581         /* reinit */
 582         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 583
 584         seed_rng();
 585
 586         if (options.user == NULL)
 587                 options.user = xstrdup(pw->pw_name);
 588
 589         if (options.hostname != NULL)
 590                 host = options.hostname;
 591
 592         /* force lowercase for hostkey matching */
 593         if (options.host_key_alias != NULL) {
 594                 for (p = options.host_key_alias; *p; p++)
 595                         if (isupper(*p))
 596                                 *p = tolower(*p);
 597         }
 598
 599         if (options.proxy_command != NULL &&
 600             strcmp(options.proxy_command, "none") == 0)
 601                 options.proxy_command = NULL;
 602
 603         /* Open a connection to the remote host. */
 604         if (ssh_connect(host, &hostaddr, options.port,
 605             options.address_family, options.connection_attempts,
 606 #ifdef HAVE_CYGWIN
 607             options.use_privileged_port,
 608 #else
 609             original_effective_uid == 0 && options.use_privileged_port,
 610 #endif
 611             options.proxy_command) != 0)
 612                 exit(1);
 613
 614         /*
 615          * If we successfully made the connection, load the host private key
 616          * in case we will need it later for combined rsa-rhosts
 617          * authentication. This must be done before releasing extra
 618          * privileges, because the file is only readable by root.
 619          * If we cannot access the private keys, load the public keys
 620          * instead and try to execute the ssh-keysign helper instead.
 621          */
 622         sensitive_data.nkeys = 0;
 623         sensitive_data.keys = NULL;
 624         sensitive_data.external_keysign = 0;
 625         if (options.rhosts_rsa_authentication ||
 626             options.hostbased_authentication) {
 627                 sensitive_data.nkeys = 3;
 628                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 629                     sizeof(Key));
 630
 631                 PRIV_START;
 632                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 633                     _PATH_HOST_KEY_FILE, "", NULL);
 634                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 635                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 636                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 637                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 638                 PRIV_END;
 639
 640                 if (options.hostbased_authentication == 1 &&
 641                     sensitive_data.keys[0] == NULL &&
 642                     sensitive_data.keys[1] == NULL &&
 643                     sensitive_data.keys[2] == NULL) {
 644                         sensitive_data.keys[1] = key_load_public(
 645                             _PATH_HOST_DSA_KEY_FILE, NULL);
 646                         sensitive_data.keys[2] = key_load_public(
 647                             _PATH_HOST_RSA_KEY_FILE, NULL);
 648                         sensitive_data.external_keysign = 1;
 649                 }
 650         }
 651         /*
 652          * Get rid of any extra privileges that we may have.  We will no
 653          * longer need them.  Also, extra privileges could make it very hard
 654          * to read identity files and other non-world-readable files from the
 655          * user's home directory if it happens to be on a NFS volume where
 656          * root is mapped to nobody.
 657          */
 658         seteuid(original_real_uid);
 659         setuid(original_real_uid);
 660
 661         /*
 662          * Now that we are back to our own permissions, create ~/.ssh
 663          * directory if it doesn\'t already exist.
 664          */
 665         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 666         if (stat(buf, &st) < 0)
 667                 if (mkdir(buf, 0700) < 0)
 668                         error("Could not create directory '%.200s'.", buf);
 669
 670         /* load options.identity_files */
 671         load_public_identity_files();
 672
 673         /* Expand ~ in known host file names. */
 674         /* XXX mem-leaks: */
 675         options.system_hostfile =
 676             tilde_expand_filename(options.system_hostfile, original_real_uid);
 677         options.user_hostfile =
 678             tilde_expand_filename(options.user_hostfile, original_real_uid);
 679         options.system_hostfile2 =
 680             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 681         options.user_hostfile2 =
 682             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 683
 684         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 685
 686         /* Log into the remote system.  This never returns if the login fails. */
 687         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 688
 689         /* We no longer need the private host keys.  Clear them now. */
 690         if (sensitive_data.nkeys != 0) {
 691                 for (i = 0; i < sensitive_data.nkeys; i++) {
 692                         if (sensitive_data.keys[i] != NULL) {
 693                                 /* Destroys contents safely */
 694                                 debug3("clear hostkey %d", i);
 695                                 key_free(sensitive_data.keys[i]);
 696                                 sensitive_data.keys[i] = NULL;
 697                         }
 698                 }
 699                 xfree(sensitive_data.keys);
 700         }
 701         for (i = 0; i < options.num_identity_files; i++) {
 702                 if (options.identity_files[i]) {
 703                         xfree(options.identity_files[i]);
 704                         options.identity_files[i] = NULL;
 705                 }
 706                 if (options.identity_keys[i]) {
 707                         key_free(options.identity_keys[i]);
 708                         options.identity_keys[i] = NULL;
 709                 }
 710         }
 711
 712         exit_status = compat20 ? ssh_session2() : ssh_session();
 713         packet_close();
 714
 715         /*
 716          * Send SIGHUP to proxy command if used. We don't wait() in
 717          * case it hangs and instead rely on init to reap the child
 718          */
 719         if (proxy_command_pid > 1)
 720                 kill(proxy_command_pid, SIGHUP);
 721
 722         return exit_status;
 723 }
 724
 725 static void
 726 x11_get_proto(char **_proto, char **_data)
 727 {
 728         char line[512];
 729         static char proto[512], data[512];
 730         FILE *f;
 731         int got_data = 0, i;
 732         char *display;
 733         struct stat st;
 734
 735         *_proto = proto;
 736         *_data = data;
 737         proto[0] = data[0] = '\0';
 738         if (!options.xauth_location ||
 739             (stat(options.xauth_location, &st) == -1)) {
 740                 debug("No xauth program.");
 741         } else {
 742                 if ((display = getenv("DISPLAY")) == NULL) {
 743                         debug("x11_get_proto: DISPLAY not set");
 744                         return;
 745                 }
 746                 /* Try to get Xauthority information for the display. */
 747                 if (strncmp(display, "localhost:", 10) == 0)
 748                         /*
 749                          * Handle FamilyLocal case where $DISPLAY does
 750                          * not match an authorization entry.  For this we
 751                          * just try "xauth list unix:displaynum.screennum".
 752                          * XXX: "localhost" match to determine FamilyLocal
 753                          *      is not perfect.
 754                          */
 755                         snprintf(line, sizeof line, "%s list unix:%s 2>"
 756                             _PATH_DEVNULL, options.xauth_location, display+10);
 757                 else
 758                         snprintf(line, sizeof line, "%s list %.200s 2>"
 759                             _PATH_DEVNULL, options.xauth_location, display);
 760                 debug2("x11_get_proto: %s", line);
 761                 f = popen(line, "r");
 762                 if (f && fgets(line, sizeof(line), f) &&
 763                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 764                         got_data = 1;
 765                 if (f)
 766                         pclose(f);
 767         }
 768         /*
 769          * If we didn't get authentication data, just make up some
 770          * data.  The forwarding code will check the validity of the
 771          * response anyway, and substitute this data.  The X11
 772          * server, however, will ignore this fake data and use
 773          * whatever authentication mechanisms it was using otherwise
 774          * for the local connection.
 775          */
 776         if (!got_data) {
 777                 u_int32_t rand = 0;
 778
 779                 logit("Warning: No xauth data; using fake authentication data for X11 forwarding.");
 780                 strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
 781                 for (i = 0; i < 16; i++) {
 782                         if (i % 4 == 0)
 783                                 rand = arc4random();
 784                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
 785                         rand >>= 8;
 786                 }
 787         }
 788 }
 789
 790 static void
 791 ssh_init_forwarding(void)
 792 {
 793         int success = 0;
 794         int i;
 795
 796         /* Initiate local TCP/IP port forwardings. */
 797         for (i = 0; i < options.num_local_forwards; i++) {
 798                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
 799                     options.local_forwards[i].port,
 800                     options.local_forwards[i].host,
 801                     options.local_forwards[i].host_port);
 802                 success += channel_setup_local_fwd_listener(
 803                     options.local_forwards[i].port,
 804                     options.local_forwards[i].host,
 805                     options.local_forwards[i].host_port,
 806                     options.gateway_ports);
 807         }
 808         if (i > 0 && success == 0)
 809                 error("Could not request local forwarding.");
 810
 811         /* Initiate remote TCP/IP port forwardings. */
 812         for (i = 0; i < options.num_remote_forwards; i++) {
 813                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
 814                     options.remote_forwards[i].port,
 815                     options.remote_forwards[i].host,
 816                     options.remote_forwards[i].host_port);
 817                 channel_request_remote_forwarding(
 818                     options.remote_forwards[i].port,
 819                     options.remote_forwards[i].host,
 820                     options.remote_forwards[i].host_port);
 821         }
 822 }
 823
 824 static void
 825 check_agent_present(void)
 826 {
 827         if (options.forward_agent) {
 828                 /* Clear agent forwarding if we don\'t have an agent. */
 829                 if (!ssh_agent_present())
 830                         options.forward_agent = 0;
 831         }
 832 }
 833
 834 static int
 835 ssh_session(void)
 836 {
 837         int type;
 838         int interactive = 0;
 839         int have_tty = 0;
 840         struct winsize ws;
 841         char *cp;
 842
 843         /* Enable compression if requested. */
 844         if (options.compression) {
 845                 debug("Requesting compression at level %d.", options.compression_level);
 846
 847                 if (options.compression_level < 1 || options.compression_level > 9)
 848                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 849
 850                 /* Send the request. */
 851                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 852                 packet_put_int(options.compression_level);
 853                 packet_send();
 854                 packet_write_wait();
 855                 type = packet_read();
 856                 if (type == SSH_SMSG_SUCCESS)
 857                         packet_start_compression(options.compression_level);
 858                 else if (type == SSH_SMSG_FAILURE)
 859                         logit("Warning: Remote host refused compression.");
 860                 else
 861                         packet_disconnect("Protocol error waiting for compression response.");
 862         }
 863         /* Allocate a pseudo tty if appropriate. */
 864         if (tty_flag) {
 865                 debug("Requesting pty.");
 866
 867                 /* Start the packet. */
 868                 packet_start(SSH_CMSG_REQUEST_PTY);
 869
 870                 /* Store TERM in the packet.  There is no limit on the
 871                    length of the string. */
 872                 cp = getenv("TERM");
 873                 if (!cp)
 874                         cp = "";
 875                 packet_put_cstring(cp);
 876
 877                 /* Store window size in the packet. */
 878                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 879                         memset(&ws, 0, sizeof(ws));
 880                 packet_put_int(ws.ws_row);
 881                 packet_put_int(ws.ws_col);
 882                 packet_put_int(ws.ws_xpixel);
 883                 packet_put_int(ws.ws_ypixel);
 884
 885                 /* Store tty modes in the packet. */
 886                 tty_make_modes(fileno(stdin), NULL);
 887
 888                 /* Send the packet, and wait for it to leave. */
 889                 packet_send();
 890                 packet_write_wait();
 891
 892                 /* Read response from the server. */
 893                 type = packet_read();
 894                 if (type == SSH_SMSG_SUCCESS) {
 895                         interactive = 1;
 896                         have_tty = 1;
 897                 } else if (type == SSH_SMSG_FAILURE)
 898                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 899                 else
 900                         packet_disconnect("Protocol error waiting for pty request response.");
 901         }
 902         /* Request X11 forwarding if enabled and DISPLAY is set. */
 903         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 904                 char *proto, *data;
 905                 /* Get reasonable local authentication information. */
 906                 x11_get_proto(&proto, &data);
 907                 /* Request forwarding with authentication spoofing. */
 908                 debug("Requesting X11 forwarding with authentication spoofing.");
 909                 x11_request_forwarding_with_spoofing(0, proto, data);
 910
 911                 /* Read response from the server. */
 912                 type = packet_read();
 913                 if (type == SSH_SMSG_SUCCESS) {
 914                         interactive = 1;
 915                 } else if (type == SSH_SMSG_FAILURE) {
 916                         logit("Warning: Remote host denied X11 forwarding.");
 917                 } else {
 918                         packet_disconnect("Protocol error waiting for X11 forwarding");
 919                 }
 920         }
 921         /* Tell the packet module whether this is an interactive session. */
 922         packet_set_interactive(interactive);
 923
 924         /* Request authentication agent forwarding if appropriate. */
 925         check_agent_present();
 926
 927         if (options.forward_agent) {
 928                 debug("Requesting authentication agent forwarding.");
 929                 auth_request_forwarding();
 930
 931                 /* Read response from the server. */
 932                 type = packet_read();
 933                 packet_check_eom();
 934                 if (type != SSH_SMSG_SUCCESS)
 935                         logit("Warning: Remote host denied authentication agent forwarding.");
 936         }
 937
 938         /* Initiate port forwardings. */
 939         ssh_init_forwarding();
 940
 941         /* If requested, let ssh continue in the background. */
 942         if (fork_after_authentication_flag)
 943                 if (daemon(1, 1) < 0)
 944                         fatal("daemon() failed: %.200s", strerror(errno));
 945
 946         /*
 947          * If a command was specified on the command line, execute the
 948          * command now. Otherwise request the server to start a shell.
 949          */
 950         if (buffer_len(&command) > 0) {
 951                 int len = buffer_len(&command);
 952                 if (len > 900)
 953                         len = 900;
 954                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 955                 packet_start(SSH_CMSG_EXEC_CMD);
 956                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 957                 packet_send();
 958                 packet_write_wait();
 959         } else {
 960                 debug("Requesting shell.");
 961                 packet_start(SSH_CMSG_EXEC_SHELL);
 962                 packet_send();
 963                 packet_write_wait();
 964         }
 965
 966         /* Enter the interactive session. */
 967         return client_loop(have_tty, tty_flag ?
 968             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
 969 }
 970
 971 static void
 972 client_subsystem_reply(int type, u_int32_t seq, void *ctxt)
 973 {
 974         int id, len;
 975
 976         id = packet_get_int();
 977         len = buffer_len(&command);
 978         if (len > 900)
 979                 len = 900;
 980         packet_check_eom();
 981         if (type == SSH2_MSG_CHANNEL_FAILURE)
 982                 fatal("Request for subsystem '%.*s' failed on channel %d",
 983                     len, (u_char *)buffer_ptr(&command), id);
 984 }
 985
 986 void
 987 client_global_request_reply(int type, u_int32_t seq, void *ctxt)
 988 {
 989         int i;
 990
 991         i = client_global_request_id++;
 992         if (i >= options.num_remote_forwards) {
 993                 debug("client_global_request_reply: too many replies %d > %d",
 994                     i, options.num_remote_forwards);
 995                 return;
 996         }
 997         debug("remote forward %s for: listen %d, connect %s:%d",
 998             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
 999             options.remote_forwards[i].port,
1000             options.remote_forwards[i].host,
1001             options.remote_forwards[i].host_port);
1002         if (type == SSH2_MSG_REQUEST_FAILURE)
1003                 logit("Warning: remote port forwarding failed for listen port %d",
1004                     options.remote_forwards[i].port);
1005 }
1006
1007 /* request pty/x11/agent/tcpfwd/shell for channel */
1008 static void
1009 ssh_session2_setup(int id, void *arg)
1010 {
1011         int len;
1012         int interactive = 0;
1013         struct termios tio;
1014
1015         debug2("ssh_session2_setup: id %d", id);
1016
1017         if (tty_flag) {
1018                 struct winsize ws;
1019                 char *cp;
1020                 cp = getenv("TERM");
1021                 if (!cp)
1022                         cp = "";
1023                 /* Store window size in the packet. */
1024                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1025                         memset(&ws, 0, sizeof(ws));
1026
1027                 channel_request_start(id, "pty-req", 0);
1028                 packet_put_cstring(cp);
1029                 packet_put_int(ws.ws_col);
1030                 packet_put_int(ws.ws_row);
1031                 packet_put_int(ws.ws_xpixel);
1032                 packet_put_int(ws.ws_ypixel);
1033                 tio = get_saved_tio();
1034                 tty_make_modes(/*ignored*/ 0, &tio);
1035                 packet_send();
1036                 interactive = 1;
1037                 /* XXX wait for reply */
1038         }
1039         if (options.forward_x11 &&
1040             getenv("DISPLAY") != NULL) {
1041                 char *proto, *data;
1042                 /* Get reasonable local authentication information. */
1043                 x11_get_proto(&proto, &data);
1044                 /* Request forwarding with authentication spoofing. */
1045                 debug("Requesting X11 forwarding with authentication spoofing.");
1046                 x11_request_forwarding_with_spoofing(id, proto, data);
1047                 interactive = 1;
1048                 /* XXX wait for reply */
1049         }
1050
1051         check_agent_present();
1052         if (options.forward_agent) {
1053                 debug("Requesting authentication agent forwarding.");
1054                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1055                 packet_send();
1056         }
1057
1058         len = buffer_len(&command);
1059         if (len > 0) {
1060                 if (len > 900)
1061                         len = 900;
1062                 if (subsystem_flag) {
1063                         debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command));
1064                         channel_request_start(id, "subsystem", /*want reply*/ 1);
1065                         /* register callback for reply */
1066                         /* XXX we assume that client_loop has already been called */
1067                         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
1068                         dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1069                 } else {
1070                         debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1071                         channel_request_start(id, "exec", 0);
1072                 }
1073                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1074                 packet_send();
1075         } else {
1076                 channel_request_start(id, "shell", 0);
1077                 packet_send();
1078         }
1079
1080         packet_set_interactive(interactive);
1081 }
1082
1083 /* open new channel for a session */
1084 static int
1085 ssh_session2_open(void)
1086 {
1087         Channel *c;
1088         int window, packetmax, in, out, err;
1089
1090         if (stdin_null_flag) {
1091                 in = open(_PATH_DEVNULL, O_RDONLY);
1092         } else {
1093                 in = dup(STDIN_FILENO);
1094         }
1095         out = dup(STDOUT_FILENO);
1096         err = dup(STDERR_FILENO);
1097
1098         if (in < 0 || out < 0 || err < 0)
1099                 fatal("dup() in/out/err failed");
1100
1101         /* enable nonblocking unless tty */
1102         if (!isatty(in))
1103                 set_nonblock(in);
1104         if (!isatty(out))
1105                 set_nonblock(out);
1106         if (!isatty(err))
1107                 set_nonblock(err);
1108
1109         window = CHAN_SES_WINDOW_DEFAULT;
1110         packetmax = CHAN_SES_PACKET_DEFAULT;
1111         if (tty_flag) {
1112                 window >>= 1;
1113                 packetmax >>= 1;
1114         }
1115         c = channel_new(
1116             "session", SSH_CHANNEL_OPENING, in, out, err,
1117             window, packetmax, CHAN_EXTENDED_WRITE,
1118             "client-session", /*nonblock*/0);
1119
1120         debug3("ssh_session2_open: channel_new: %d", c->self);
1121
1122         channel_send_open(c->self);
1123         if (!no_shell_flag)
1124                 channel_register_confirm(c->self, ssh_session2_setup);
1125
1126         return c->self;
1127 }
1128
1129 static int
1130 ssh_session2(void)
1131 {
1132         int id = -1;
1133
1134         /* XXX should be pre-session */
1135         ssh_init_forwarding();
1136
1137         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1138                 id = ssh_session2_open();
1139
1140         /* If requested, let ssh continue in the background. */
1141         if (fork_after_authentication_flag)
1142                 if (daemon(1, 1) < 0)
1143                         fatal("daemon() failed: %.200s", strerror(errno));
1144
1145         return client_loop(tty_flag, tty_flag ?
1146             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1147 }
1148
1149 static void
1150 load_public_identity_files(void)
1151 {
1152         char *filename;
1153         int i = 0;
1154         Key *public;
1155 #ifdef SMARTCARD
1156         Key **keys;
1157
1158         if (options.smartcard_device != NULL &&
1159             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1160             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1161                 int count = 0;
1162                 for (i = 0; keys[i] != NULL; i++) {
1163                         count++;
1164                         memmove(&options.identity_files[1], &options.identity_files[0],
1165                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1166                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1167                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1168                         options.num_identity_files++;
1169                         options.identity_keys[0] = keys[i];
1170                         options.identity_files[0] = sc_get_key_label(keys[i]);
1171                 }
1172                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1173                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1174                 i = count;
1175                 xfree(keys);
1176         }
1177 #endif /* SMARTCARD */
1178         for (; i < options.num_identity_files; i++) {
1179                 filename = tilde_expand_filename(options.identity_files[i],
1180                     original_real_uid);
1181                 public = key_load_public(filename, NULL);
1182                 debug("identity file %s type %d", filename,
1183                     public ? public->type : -1);
1184                 xfree(options.identity_files[i]);
1185                 options.identity_files[i] = filename;
1186                 options.identity_keys[i] = public;
1187         }
1188 }