openssh/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 1.201 2003/09/01 18:15:50 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, "  -X          Enable X11 connection forwarding.\n");
 158         fprintf(stderr, "  -x          Disable X11 connection forwarding (default).\n");
 159         fprintf(stderr, "  -i file     Identity for public key authentication "
 160             "(default: ~/.ssh/identity)\n");
 161 #ifdef SMARTCARD
 162         fprintf(stderr, "  -I reader   Set smartcard reader.\n");
 163 #endif
 164         fprintf(stderr, "  -t          Tty; allocate a tty even if command is given.\n");
 165         fprintf(stderr, "  -T          Do not allocate a tty.\n");
 166         fprintf(stderr, "  -v          Verbose; display verbose debugging messages.\n");
 167         fprintf(stderr, "              Multiple -v increases verbosity.\n");
 168         fprintf(stderr, "  -V          Display version number only.\n");
 169         fprintf(stderr, "  -q          Quiet; don't display any warning messages.\n");
 170         fprintf(stderr, "  -f          Fork into background after authentication.\n");
 171         fprintf(stderr, "  -e char     Set escape character; ``none'' = disable (default: ~).\n");
 172
 173         fprintf(stderr, "  -c cipher   Select encryption algorithm\n");
 174         fprintf(stderr, "  -m macs     Specify MAC algorithms for protocol version 2.\n");
 175         fprintf(stderr, "  -p port     Connect to this port.  Server must be on the same port.\n");
 176         fprintf(stderr, "  -L listen-port:host:port   Forward local port to remote address\n");
 177         fprintf(stderr, "  -R listen-port:host:port   Forward remote port to local address\n");
 178         fprintf(stderr, "              These cause %s to listen for connections on a port, and\n", __progname);
 179         fprintf(stderr, "              forward them to the other side by connecting to host:port.\n");
 180         fprintf(stderr, "  -D port     Enable dynamic application-level port forwarding.\n");
 181         fprintf(stderr, "  -C          Enable compression.\n");
 182         fprintf(stderr, "  -N          Do not execute a shell or command.\n");
 183         fprintf(stderr, "  -g          Allow remote hosts to connect to forwarded ports.\n");
 184         fprintf(stderr, "  -1          Force protocol version 1.\n");
 185         fprintf(stderr, "  -2          Force protocol version 2.\n");
 186         fprintf(stderr, "  -4          Use IPv4 only.\n");
 187         fprintf(stderr, "  -6          Use IPv6 only.\n");
 188         fprintf(stderr, "  -o 'option' Process the option as if it was read from a configuration file.\n");
 189         fprintf(stderr, "  -s          Invoke command (mandatory) as SSH2 subsystem.\n");
 190         fprintf(stderr, "  -b addr     Local IP address.\n");
 191         exit(1);
 192 }
 193
 194 static int ssh_session(void);
 195 static int ssh_session2(void);
 196 static void load_public_identity_files(void);
 197
 198 /*
 199  * Main program for the ssh client.
 200  */
 201 int
 202 main(int ac, char **av)
 203 {
 204         int i, opt, exit_status;
 205         u_short fwd_port, fwd_host_port;
 206         char sfwd_port[6], sfwd_host_port[6];
 207         char *p, *cp, buf[256];
 208         struct stat st;
 209         struct passwd *pw;
 210         int dummy;
 211         extern int optind, optreset;
 212         extern char *optarg;
 213
 214         __progname = ssh_get_progname(av[0]);
 215         init_rng();
 216
 217         /*
 218          * Save the original real uid.  It will be needed later (uid-swapping
 219          * may clobber the real uid).
 220          */
 221         original_real_uid = getuid();
 222         original_effective_uid = geteuid();
 223
 224         /*
 225          * Use uid-swapping to give up root privileges for the duration of
 226          * option processing.  We will re-instantiate the rights when we are
 227          * ready to create the privileged port, and will permanently drop
 228          * them when the port has been created (actually, when the connection
 229          * has been made, as we may need to create the port several times).
 230          */
 231         PRIV_END;
 232
 233 #ifdef HAVE_SETRLIMIT
 234         /* If we are installed setuid root be careful to not drop core. */
 235         if (original_real_uid != original_effective_uid) {
 236                 struct rlimit rlim;
 237                 rlim.rlim_cur = rlim.rlim_max = 0;
 238                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 239                         fatal("setrlimit failed: %.100s", strerror(errno));
 240         }
 241 #endif
 242         /* Get user data. */
 243         pw = getpwuid(original_real_uid);
 244         if (!pw) {
 245                 logit("You don't exist, go away!");
 246                 exit(1);
 247         }
 248         /* Take a copy of the returned structure. */
 249         pw = pwcopy(pw);
 250
 251         /*
 252          * Set our umask to something reasonable, as some files are created
 253          * with the default umask.  This will make them world-readable but
 254          * writable only by the owner, which is ok for all files for which we
 255          * don't set the modes explicitly.
 256          */
 257         umask(022);
 258
 259         /* Initialize option structure to indicate that no values have been set. */
 260         initialize_options(&options);
 261
 262         /* Parse command-line arguments. */
 263         host = NULL;
 264
 265 again:
 266         while ((opt = getopt(ac, av,
 267             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVX")) != -1) {
 268                 switch (opt) {
 269                 case '1':
 270                         options.protocol = SSH_PROTO_1;
 271                         break;
 272                 case '2':
 273                         options.protocol = SSH_PROTO_2;
 274                         break;
 275                 case '4':
 276                         options.address_family = AF_INET;
 277                         break;
 278                 case '6':
 279                         options.address_family = AF_INET6;
 280                         break;
 281                 case 'n':
 282                         stdin_null_flag = 1;
 283                         break;
 284                 case 'f':
 285                         fork_after_authentication_flag = 1;
 286                         stdin_null_flag = 1;
 287                         break;
 288                 case 'x':
 289                         options.forward_x11 = 0;
 290                         break;
 291                 case 'X':
 292                         options.forward_x11 = 1;
 293                         break;
 294                 case 'g':
 295                         options.gateway_ports = 1;
 296                         break;
 297                 case 'P':       /* deprecated */
 298                         options.use_privileged_port = 0;
 299                         break;
 300                 case 'a':
 301                         options.forward_agent = 0;
 302                         break;
 303                 case 'A':
 304                         options.forward_agent = 1;
 305                         break;
 306                 case 'k':
 307                         /* ignored for backward compatibility */
 308                         break;
 309                 case 'i':
 310                         if (stat(optarg, &st) < 0) {
 311                                 fprintf(stderr, "Warning: Identity file %s "
 312                                     "does not exist.\n", optarg);
 313                                 break;
 314                         }
 315                         if (options.num_identity_files >=
 316                             SSH_MAX_IDENTITY_FILES)
 317                                 fatal("Too many identity files specified "
 318                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 319                         options.identity_files[options.num_identity_files++] =
 320                             xstrdup(optarg);
 321                         break;
 322                 case 'I':
 323 #ifdef SMARTCARD
 324                         options.smartcard_device = xstrdup(optarg);
 325 #else
 326                         fprintf(stderr, "no support for smartcards.\n");
 327 #endif
 328                         break;
 329                 case 't':
 330                         if (tty_flag)
 331                                 force_tty_flag = 1;
 332                         tty_flag = 1;
 333                         break;
 334                 case 'v':
 335                         if (debug_flag == 0) {
 336                                 debug_flag = 1;
 337                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 338                         } else {
 339                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 340                                         options.log_level++;
 341                                 break;
 342                         }
 343                         /* fallthrough */
 344                 case 'V':
 345                         fprintf(stderr,
 346                             "%s, SSH protocols %d.%d/%d.%d, %s\n",
 347                             SSH_VERSION,
 348                             PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
 349                             PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
 350                             SSLeay_version(SSLEAY_VERSION));
 351                         if (opt == 'V')
 352                                 exit(0);
 353                         break;
 354                 case 'q':
 355                         options.log_level = SYSLOG_LEVEL_QUIET;
 356                         break;
 357                 case 'e':
 358                         if (optarg[0] == '^' && optarg[2] == 0 &&
 359                             (u_char) optarg[1] >= 64 &&
 360                             (u_char) optarg[1] < 128)
 361                                 options.escape_char = (u_char) optarg[1] & 31;
 362                         else if (strlen(optarg) == 1)
 363                                 options.escape_char = (u_char) optarg[0];
 364                         else if (strcmp(optarg, "none") == 0)
 365                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 366                         else {
 367                                 fprintf(stderr, "Bad escape character '%s'.\n",
 368                                     optarg);
 369                                 exit(1);
 370                         }
 371                         break;
 372                 case 'c':
 373                         if (ciphers_valid(optarg)) {
 374                                 /* SSH2 only */
 375                                 options.ciphers = xstrdup(optarg);
 376                                 options.cipher = SSH_CIPHER_ILLEGAL;
 377                         } else {
 378                                 /* SSH1 only */
 379                                 options.cipher = cipher_number(optarg);
 380                                 if (options.cipher == -1) {
 381                                         fprintf(stderr,
 382                                             "Unknown cipher type '%s'\n",
 383                                             optarg);
 384                                         exit(1);
 385                                 }
 386                                 if (options.cipher == SSH_CIPHER_3DES)
 387                                         options.ciphers = "3des-cbc";
 388                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 389                                         options.ciphers = "blowfish-cbc";
 390                                 else
 391                                         options.ciphers = (char *)-1;
 392                         }
 393                         break;
 394                 case 'm':
 395                         if (mac_valid(optarg))
 396                                 options.macs = xstrdup(optarg);
 397                         else {
 398                                 fprintf(stderr, "Unknown mac type '%s'\n",
 399                                     optarg);
 400                                 exit(1);
 401                         }
 402                         break;
 403                 case 'p':
 404                         options.port = a2port(optarg);
 405                         if (options.port == 0) {
 406                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 407                                 exit(1);
 408                         }
 409                         break;
 410                 case 'l':
 411                         options.user = optarg;
 412                         break;
 413
 414                 case 'L':
 415                 case 'R':
 416                         if (sscanf(optarg, "%5[0123456789]:%255[^:]:%5[0123456789]",
 417                             sfwd_port, buf, sfwd_host_port) != 3 &&
 418                             sscanf(optarg, "%5[0123456789]/%255[^/]/%5[0123456789]",
 419                             sfwd_port, buf, sfwd_host_port) != 3) {
 420                                 fprintf(stderr,
 421                                     "Bad forwarding specification '%s'\n",
 422                                     optarg);
 423                                 usage();
 424                                 /* NOTREACHED */
 425                         }
 426                         if ((fwd_port = a2port(sfwd_port)) == 0 ||
 427                             (fwd_host_port = a2port(sfwd_host_port)) == 0) {
 428                                 fprintf(stderr,
 429                                     "Bad forwarding port(s) '%s'\n", optarg);
 430                                 exit(1);
 431                         }
 432                         if (opt == 'L')
 433                                 add_local_forward(&options, fwd_port, buf,
 434                                     fwd_host_port);
 435                         else if (opt == 'R')
 436                                 add_remote_forward(&options, fwd_port, buf,
 437                                     fwd_host_port);
 438                         break;
 439
 440                 case 'D':
 441                         fwd_port = a2port(optarg);
 442                         if (fwd_port == 0) {
 443                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 444                                     optarg);
 445                                 exit(1);
 446                         }
 447                         add_local_forward(&options, fwd_port, "socks", 0);
 448                         break;
 449
 450                 case 'C':
 451                         options.compression = 1;
 452                         break;
 453                 case 'N':
 454                         no_shell_flag = 1;
 455                         no_tty_flag = 1;
 456                         break;
 457                 case 'T':
 458                         no_tty_flag = 1;
 459                         break;
 460                 case 'o':
 461                         dummy = 1;
 462                         if (process_config_line(&options, host ? host : "",
 463                             optarg, "command-line", 0, &dummy) != 0)
 464                                 exit(1);
 465                         break;
 466                 case 's':
 467                         subsystem_flag = 1;
 468                         break;
 469                 case 'b':
 470                         options.bind_address = optarg;
 471                         break;
 472                 case 'F':
 473                         config = optarg;
 474                         break;
 475                 default:
 476                         usage();
 477                 }
 478         }
 479
 480         ac -= optind;
 481         av += optind;
 482
 483         if (ac > 0 && !host && **av != '-') {
 484                 if (strrchr(*av, '@')) {
 485                         p = xstrdup(*av);
 486                         cp = strrchr(p, '@');
 487                         if (cp == NULL || cp == p)
 488                                 usage();
 489                         options.user = p;
 490                         *cp = '\0';
 491                         host = ++cp;
 492                 } else
 493                         host = *av;
 494                 if (ac > 1) {
 495                         optind = optreset = 1;
 496                         goto again;
 497                 }
 498                 ac--, av++;
 499         }
 500
 501         /* Check that we got a host name. */
 502         if (!host)
 503                 usage();
 504
 505         SSLeay_add_all_algorithms();
 506         ERR_load_crypto_strings();
 507
 508         /* Initialize the command to execute on remote host. */
 509         buffer_init(&command);
 510
 511         /*
 512          * Save the command to execute on the remote host in a buffer. There
 513          * is no limit on the length of the command, except by the maximum
 514          * packet size.  Also sets the tty flag if there is no command.
 515          */
 516         if (!ac) {
 517                 /* No command specified - execute shell on a tty. */
 518                 tty_flag = 1;
 519                 if (subsystem_flag) {
 520                         fprintf(stderr,
 521                             "You must specify a subsystem to invoke.\n");
 522                         usage();
 523                 }
 524         } else {
 525                 /* A command has been specified.  Store it into the buffer. */
 526                 for (i = 0; i < ac; i++) {
 527                         if (i)
 528                                 buffer_append(&command, " ", 1);
 529                         buffer_append(&command, av[i], strlen(av[i]));
 530                 }
 531         }
 532
 533         /* Cannot fork to background if no command. */
 534         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 535                 fatal("Cannot fork into background without a command to execute.");
 536
 537         /* Allocate a tty by default if no command specified. */
 538         if (buffer_len(&command) == 0)
 539                 tty_flag = 1;
 540
 541         /* Force no tty */
 542         if (no_tty_flag)
 543                 tty_flag = 0;
 544         /* Do not allocate a tty if stdin is not a tty. */
 545         if (!isatty(fileno(stdin)) && !force_tty_flag) {
 546                 if (tty_flag)
 547                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 548                 tty_flag = 0;
 549         }
 550
 551         /*
 552          * Initialize "log" output.  Since we are the client all output
 553          * actually goes to stderr.
 554          */
 555         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 556             SYSLOG_FACILITY_USER, 1);
 557
 558         /*
 559          * Read per-user configuration file.  Ignore the system wide config
 560          * file if the user specifies a config file on the command line.
 561          */
 562         if (config != NULL) {
 563                 if (!read_config_file(config, host, &options))
 564                         fatal("Can't open user config file %.100s: "
 565                             "%.100s", config, strerror(errno));
 566         } else  {
 567                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 568                     _PATH_SSH_USER_CONFFILE);
 569                 (void)read_config_file(buf, host, &options);
 570
 571                 /* Read systemwide configuration file after use config. */
 572                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
 573         }
 574
 575         /* Fill configuration defaults. */
 576         fill_default_options(&options);
 577
 578         channel_set_af(options.address_family);
 579
 580         /* reinit */
 581         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 582
 583         seed_rng();
 584
 585         if (options.user == NULL)
 586                 options.user = xstrdup(pw->pw_name);
 587
 588         if (options.hostname != NULL)
 589                 host = options.hostname;
 590
 591         /* force lowercase for hostkey matching */
 592         if (options.host_key_alias != NULL) {
 593                 for (p = options.host_key_alias; *p; p++)
 594                         if (isupper(*p))
 595                                 *p = tolower(*p);
 596         }
 597
 598         if (options.proxy_command != NULL &&
 599             strcmp(options.proxy_command, "none") == 0)
 600                 options.proxy_command = NULL;
 601
 602         /* Open a connection to the remote host. */
 603         if (ssh_connect(host, &hostaddr, options.port,
 604             options.address_family, options.connection_attempts,
 605 #ifdef HAVE_CYGWIN
 606             options.use_privileged_port,
 607 #else
 608             original_effective_uid == 0 && options.use_privileged_port,
 609 #endif
 610             options.proxy_command) != 0)
 611                 exit(1);
 612
 613         /*
 614          * If we successfully made the connection, load the host private key
 615          * in case we will need it later for combined rsa-rhosts
 616          * authentication. This must be done before releasing extra
 617          * privileges, because the file is only readable by root.
 618          * If we cannot access the private keys, load the public keys
 619          * instead and try to execute the ssh-keysign helper instead.
 620          */
 621         sensitive_data.nkeys = 0;
 622         sensitive_data.keys = NULL;
 623         sensitive_data.external_keysign = 0;
 624         if (options.rhosts_rsa_authentication ||
 625             options.hostbased_authentication) {
 626                 sensitive_data.nkeys = 3;
 627                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 628                     sizeof(Key));
 629
 630                 PRIV_START;
 631                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 632                     _PATH_HOST_KEY_FILE, "", NULL);
 633                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 634                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 635                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 636                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 637                 PRIV_END;
 638
 639                 if (options.hostbased_authentication == 1 &&
 640                     sensitive_data.keys[0] == NULL &&
 641                     sensitive_data.keys[1] == NULL &&
 642                     sensitive_data.keys[2] == NULL) {
 643                         sensitive_data.keys[1] = key_load_public(
 644                             _PATH_HOST_DSA_KEY_FILE, NULL);
 645                         sensitive_data.keys[2] = key_load_public(
 646                             _PATH_HOST_RSA_KEY_FILE, NULL);
 647                         sensitive_data.external_keysign = 1;
 648                 }
 649         }
 650         /*
 651          * Get rid of any extra privileges that we may have.  We will no
 652          * longer need them.  Also, extra privileges could make it very hard
 653          * to read identity files and other non-world-readable files from the
 654          * user's home directory if it happens to be on a NFS volume where
 655          * root is mapped to nobody.
 656          */
 657         seteuid(original_real_uid);
 658         setuid(original_real_uid);
 659
 660         /*
 661          * Now that we are back to our own permissions, create ~/.ssh
 662          * directory if it doesn\'t already exist.
 663          */
 664         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 665         if (stat(buf, &st) < 0)
 666                 if (mkdir(buf, 0700) < 0)
 667                         error("Could not create directory '%.200s'.", buf);
 668
 669         /* load options.identity_files */
 670         load_public_identity_files();
 671
 672         /* Expand ~ in known host file names. */
 673         /* XXX mem-leaks: */
 674         options.system_hostfile =
 675             tilde_expand_filename(options.system_hostfile, original_real_uid);
 676         options.user_hostfile =
 677             tilde_expand_filename(options.user_hostfile, original_real_uid);
 678         options.system_hostfile2 =
 679             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 680         options.user_hostfile2 =
 681             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 682
 683         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 684
 685         /* Log into the remote system.  This never returns if the login fails. */
 686         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 687
 688         /* We no longer need the private host keys.  Clear them now. */
 689         if (sensitive_data.nkeys != 0) {
 690                 for (i = 0; i < sensitive_data.nkeys; i++) {
 691                         if (sensitive_data.keys[i] != NULL) {
 692                                 /* Destroys contents safely */
 693                                 debug3("clear hostkey %d", i);
 694                                 key_free(sensitive_data.keys[i]);
 695                                 sensitive_data.keys[i] = NULL;
 696                         }
 697                 }
 698                 xfree(sensitive_data.keys);
 699         }
 700         for (i = 0; i < options.num_identity_files; i++) {
 701                 if (options.identity_files[i]) {
 702                         xfree(options.identity_files[i]);
 703                         options.identity_files[i] = NULL;
 704                 }
 705                 if (options.identity_keys[i]) {
 706                         key_free(options.identity_keys[i]);
 707                         options.identity_keys[i] = NULL;
 708                 }
 709         }
 710
 711         exit_status = compat20 ? ssh_session2() : ssh_session();
 712         packet_close();
 713
 714         /*
 715          * Send SIGHUP to proxy command if used. We don't wait() in
 716          * case it hangs and instead rely on init to reap the child
 717          */
 718         if (proxy_command_pid > 1)
 719                 kill(proxy_command_pid, SIGHUP);
 720
 721         return exit_status;
 722 }
 723
 724 static void
 725 x11_get_proto(char **_proto, char **_data)
 726 {
 727         char line[512];
 728         static char proto[512], data[512];
 729         FILE *f;
 730         int got_data = 0, i;
 731         char *display;
 732         struct stat st;
 733
 734         *_proto = proto;
 735         *_data = data;
 736         proto[0] = data[0] = '\0';
 737         if (!options.xauth_location ||
 738             (stat(options.xauth_location, &st) == -1)) {
 739                 debug("No xauth program.");
 740         } else {
 741                 if ((display = getenv("DISPLAY")) == NULL) {
 742                         debug("x11_get_proto: DISPLAY not set");
 743                         return;
 744                 }
 745                 /* Try to get Xauthority information for the display. */
 746                 if (strncmp(display, "localhost:", 10) == 0)
 747                         /*
 748                          * Handle FamilyLocal case where $DISPLAY does
 749                          * not match an authorization entry.  For this we
 750                          * just try "xauth list unix:displaynum.screennum".
 751                          * XXX: "localhost" match to determine FamilyLocal
 752                          *      is not perfect.
 753                          */
 754                         snprintf(line, sizeof line, "%s list unix:%s 2>"
 755                             _PATH_DEVNULL, options.xauth_location, display+10);
 756                 else
 757                         snprintf(line, sizeof line, "%s list %.200s 2>"
 758                             _PATH_DEVNULL, options.xauth_location, display);
 759                 debug2("x11_get_proto: %s", line);
 760                 f = popen(line, "r");
 761                 if (f && fgets(line, sizeof(line), f) &&
 762                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 763                         got_data = 1;
 764                 if (f)
 765                         pclose(f);
 766         }
 767         /*
 768          * If we didn't get authentication data, just make up some
 769          * data.  The forwarding code will check the validity of the
 770          * response anyway, and substitute this data.  The X11
 771          * server, however, will ignore this fake data and use
 772          * whatever authentication mechanisms it was using otherwise
 773          * for the local connection.
 774          */
 775         if (!got_data) {
 776                 u_int32_t rand = 0;
 777
 778                 logit("Warning: No xauth data; using fake authentication data for X11 forwarding.");
 779                 strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
 780                 for (i = 0; i < 16; i++) {
 781                         if (i % 4 == 0)
 782                                 rand = arc4random();
 783                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
 784                         rand >>= 8;
 785                 }
 786         }
 787 }
 788
 789 static void
 790 ssh_init_forwarding(void)
 791 {
 792         int success = 0;
 793         int i;
 794
 795         /* Initiate local TCP/IP port forwardings. */
 796         for (i = 0; i < options.num_local_forwards; i++) {
 797                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
 798                     options.local_forwards[i].port,
 799                     options.local_forwards[i].host,
 800                     options.local_forwards[i].host_port);
 801                 success += channel_setup_local_fwd_listener(
 802                     options.local_forwards[i].port,
 803                     options.local_forwards[i].host,
 804                     options.local_forwards[i].host_port,
 805                     options.gateway_ports);
 806         }
 807         if (i > 0 && success == 0)
 808                 error("Could not request local forwarding.");
 809
 810         /* Initiate remote TCP/IP port forwardings. */
 811         for (i = 0; i < options.num_remote_forwards; i++) {
 812                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
 813                     options.remote_forwards[i].port,
 814                     options.remote_forwards[i].host,
 815                     options.remote_forwards[i].host_port);
 816                 channel_request_remote_forwarding(
 817                     options.remote_forwards[i].port,
 818                     options.remote_forwards[i].host,
 819                     options.remote_forwards[i].host_port);
 820         }
 821 }
 822
 823 static void
 824 check_agent_present(void)
 825 {
 826         if (options.forward_agent) {
 827                 /* Clear agent forwarding if we don\'t have an agent. */
 828                 if (!ssh_agent_present())
 829                         options.forward_agent = 0;
 830         }
 831 }
 832
 833 static int
 834 ssh_session(void)
 835 {
 836         int type;
 837         int interactive = 0;
 838         int have_tty = 0;
 839         struct winsize ws;
 840         char *cp;
 841
 842         /* Enable compression if requested. */
 843         if (options.compression) {
 844                 debug("Requesting compression at level %d.", options.compression_level);
 845
 846                 if (options.compression_level < 1 || options.compression_level > 9)
 847                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 848
 849                 /* Send the request. */
 850                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 851                 packet_put_int(options.compression_level);
 852                 packet_send();
 853                 packet_write_wait();
 854                 type = packet_read();
 855                 if (type == SSH_SMSG_SUCCESS)
 856                         packet_start_compression(options.compression_level);
 857                 else if (type == SSH_SMSG_FAILURE)
 858                         logit("Warning: Remote host refused compression.");
 859                 else
 860                         packet_disconnect("Protocol error waiting for compression response.");
 861         }
 862         /* Allocate a pseudo tty if appropriate. */
 863         if (tty_flag) {
 864                 debug("Requesting pty.");
 865
 866                 /* Start the packet. */
 867                 packet_start(SSH_CMSG_REQUEST_PTY);
 868
 869                 /* Store TERM in the packet.  There is no limit on the
 870                    length of the string. */
 871                 cp = getenv("TERM");
 872                 if (!cp)
 873                         cp = "";
 874                 packet_put_cstring(cp);
 875
 876                 /* Store window size in the packet. */
 877                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 878                         memset(&ws, 0, sizeof(ws));
 879                 packet_put_int(ws.ws_row);
 880                 packet_put_int(ws.ws_col);
 881                 packet_put_int(ws.ws_xpixel);
 882                 packet_put_int(ws.ws_ypixel);
 883
 884                 /* Store tty modes in the packet. */
 885                 tty_make_modes(fileno(stdin), NULL);
 886
 887                 /* Send the packet, and wait for it to leave. */
 888                 packet_send();
 889                 packet_write_wait();
 890
 891                 /* Read response from the server. */
 892                 type = packet_read();
 893                 if (type == SSH_SMSG_SUCCESS) {
 894                         interactive = 1;
 895                         have_tty = 1;
 896                 } else if (type == SSH_SMSG_FAILURE)
 897                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 898                 else
 899                         packet_disconnect("Protocol error waiting for pty request response.");
 900         }
 901         /* Request X11 forwarding if enabled and DISPLAY is set. */
 902         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 903                 char *proto, *data;
 904                 /* Get reasonable local authentication information. */
 905                 x11_get_proto(&proto, &data);
 906                 /* Request forwarding with authentication spoofing. */
 907                 debug("Requesting X11 forwarding with authentication spoofing.");
 908                 x11_request_forwarding_with_spoofing(0, proto, data);
 909
 910                 /* Read response from the server. */
 911                 type = packet_read();
 912                 if (type == SSH_SMSG_SUCCESS) {
 913                         interactive = 1;
 914                 } else if (type == SSH_SMSG_FAILURE) {
 915                         logit("Warning: Remote host denied X11 forwarding.");
 916                 } else {
 917                         packet_disconnect("Protocol error waiting for X11 forwarding");
 918                 }
 919         }
 920         /* Tell the packet module whether this is an interactive session. */
 921         packet_set_interactive(interactive);
 922
 923         /* Request authentication agent forwarding if appropriate. */
 924         check_agent_present();
 925
 926         if (options.forward_agent) {
 927                 debug("Requesting authentication agent forwarding.");
 928                 auth_request_forwarding();
 929
 930                 /* Read response from the server. */
 931                 type = packet_read();
 932                 packet_check_eom();
 933                 if (type != SSH_SMSG_SUCCESS)
 934                         logit("Warning: Remote host denied authentication agent forwarding.");
 935         }
 936
 937         /* Initiate port forwardings. */
 938         ssh_init_forwarding();
 939
 940         /* If requested, let ssh continue in the background. */
 941         if (fork_after_authentication_flag)
 942                 if (daemon(1, 1) < 0)
 943                         fatal("daemon() failed: %.200s", strerror(errno));
 944
 945         /*
 946          * If a command was specified on the command line, execute the
 947          * command now. Otherwise request the server to start a shell.
 948          */
 949         if (buffer_len(&command) > 0) {
 950                 int len = buffer_len(&command);
 951                 if (len > 900)
 952                         len = 900;
 953                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 954                 packet_start(SSH_CMSG_EXEC_CMD);
 955                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 956                 packet_send();
 957                 packet_write_wait();
 958         } else {
 959                 debug("Requesting shell.");
 960                 packet_start(SSH_CMSG_EXEC_SHELL);
 961                 packet_send();
 962                 packet_write_wait();
 963         }
 964
 965         /* Enter the interactive session. */
 966         return client_loop(have_tty, tty_flag ?
 967             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
 968 }
 969
 970 static void
 971 client_subsystem_reply(int type, u_int32_t seq, void *ctxt)
 972 {
 973         int id, len;
 974
 975         id = packet_get_int();
 976         len = buffer_len(&command);
 977         if (len > 900)
 978                 len = 900;
 979         packet_check_eom();
 980         if (type == SSH2_MSG_CHANNEL_FAILURE)
 981                 fatal("Request for subsystem '%.*s' failed on channel %d",
 982                     len, (u_char *)buffer_ptr(&command), id);
 983 }
 984
 985 void
 986 client_global_request_reply(int type, u_int32_t seq, void *ctxt)
 987 {
 988         int i;
 989
 990         i = client_global_request_id++;
 991         if (i >= options.num_remote_forwards) {
 992                 debug("client_global_request_reply: too many replies %d > %d",
 993                     i, options.num_remote_forwards);
 994                 return;
 995         }
 996         debug("remote forward %s for: listen %d, connect %s:%d",
 997             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
 998             options.remote_forwards[i].port,
 999             options.remote_forwards[i].host,
1000             options.remote_forwards[i].host_port);
1001         if (type == SSH2_MSG_REQUEST_FAILURE)
1002                 logit("Warning: remote port forwarding failed for listen port %d",
1003                     options.remote_forwards[i].port);
1004 }
1005
1006 /* request pty/x11/agent/tcpfwd/shell for channel */
1007 static void
1008 ssh_session2_setup(int id, void *arg)
1009 {
1010         int len;
1011         int interactive = 0;
1012         struct termios tio;
1013
1014         debug2("ssh_session2_setup: id %d", id);
1015
1016         if (tty_flag) {
1017                 struct winsize ws;
1018                 char *cp;
1019                 cp = getenv("TERM");
1020                 if (!cp)
1021                         cp = "";
1022                 /* Store window size in the packet. */
1023                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1024                         memset(&ws, 0, sizeof(ws));
1025
1026                 channel_request_start(id, "pty-req", 0);
1027                 packet_put_cstring(cp);
1028                 packet_put_int(ws.ws_col);
1029                 packet_put_int(ws.ws_row);
1030                 packet_put_int(ws.ws_xpixel);
1031                 packet_put_int(ws.ws_ypixel);
1032                 tio = get_saved_tio();
1033                 tty_make_modes(/*ignored*/ 0, &tio);
1034                 packet_send();
1035                 interactive = 1;
1036                 /* XXX wait for reply */
1037         }
1038         if (options.forward_x11 &&
1039             getenv("DISPLAY") != NULL) {
1040                 char *proto, *data;
1041                 /* Get reasonable local authentication information. */
1042                 x11_get_proto(&proto, &data);
1043                 /* Request forwarding with authentication spoofing. */
1044                 debug("Requesting X11 forwarding with authentication spoofing.");
1045                 x11_request_forwarding_with_spoofing(id, proto, data);
1046                 interactive = 1;
1047                 /* XXX wait for reply */
1048         }
1049
1050         check_agent_present();
1051         if (options.forward_agent) {
1052                 debug("Requesting authentication agent forwarding.");
1053                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1054                 packet_send();
1055         }
1056
1057         len = buffer_len(&command);
1058         if (len > 0) {
1059                 if (len > 900)
1060                         len = 900;
1061                 if (subsystem_flag) {
1062                         debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command));
1063                         channel_request_start(id, "subsystem", /*want reply*/ 1);
1064                         /* register callback for reply */
1065                         /* XXX we assume that client_loop has already been called */
1066                         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
1067                         dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1068                 } else {
1069                         debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1070                         channel_request_start(id, "exec", 0);
1071                 }
1072                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1073                 packet_send();
1074         } else {
1075                 channel_request_start(id, "shell", 0);
1076                 packet_send();
1077         }
1078
1079         packet_set_interactive(interactive);
1080 }
1081
1082 /* open new channel for a session */
1083 static int
1084 ssh_session2_open(void)
1085 {
1086         Channel *c;
1087         int window, packetmax, in, out, err;
1088
1089         if (stdin_null_flag) {
1090                 in = open(_PATH_DEVNULL, O_RDONLY);
1091         } else {
1092                 in = dup(STDIN_FILENO);
1093         }
1094         out = dup(STDOUT_FILENO);
1095         err = dup(STDERR_FILENO);
1096
1097         if (in < 0 || out < 0 || err < 0)
1098                 fatal("dup() in/out/err failed");
1099
1100         /* enable nonblocking unless tty */
1101         if (!isatty(in))
1102                 set_nonblock(in);
1103         if (!isatty(out))
1104                 set_nonblock(out);
1105         if (!isatty(err))
1106                 set_nonblock(err);
1107
1108         window = CHAN_SES_WINDOW_DEFAULT;
1109         packetmax = CHAN_SES_PACKET_DEFAULT;
1110         if (tty_flag) {
1111                 window >>= 1;
1112                 packetmax >>= 1;
1113         }
1114         c = channel_new(
1115             "session", SSH_CHANNEL_OPENING, in, out, err,
1116             window, packetmax, CHAN_EXTENDED_WRITE,
1117             "client-session", /*nonblock*/0);
1118
1119         debug3("ssh_session2_open: channel_new: %d", c->self);
1120
1121         channel_send_open(c->self);
1122         if (!no_shell_flag)
1123                 channel_register_confirm(c->self, ssh_session2_setup);
1124
1125         return c->self;
1126 }
1127
1128 static int
1129 ssh_session2(void)
1130 {
1131         int id = -1;
1132
1133         /* XXX should be pre-session */
1134         ssh_init_forwarding();
1135
1136         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1137                 id = ssh_session2_open();
1138
1139         /* If requested, let ssh continue in the background. */
1140         if (fork_after_authentication_flag)
1141                 if (daemon(1, 1) < 0)
1142                         fatal("daemon() failed: %.200s", strerror(errno));
1143
1144         return client_loop(tty_flag, tty_flag ?
1145             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1146 }
1147
1148 static void
1149 load_public_identity_files(void)
1150 {
1151         char *filename;
1152         int i = 0;
1153         Key *public;
1154 #ifdef SMARTCARD
1155         Key **keys;
1156
1157         if (options.smartcard_device != NULL &&
1158             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1159             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1160                 int count = 0;
1161                 for (i = 0; keys[i] != NULL; i++) {
1162                         count++;
1163                         memmove(&options.identity_files[1], &options.identity_files[0],
1164                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1165                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1166                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1167                         options.num_identity_files++;
1168                         options.identity_keys[0] = keys[i];
1169                         options.identity_files[0] = sc_get_key_label(keys[i]);
1170                 }
1171                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1172                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1173                 i = count;
1174                 xfree(keys);
1175         }
1176 #endif /* SMARTCARD */
1177         for (; i < options.num_identity_files; i++) {
1178                 filename = tilde_expand_filename(options.identity_files[i],
1179                     original_real_uid);
1180                 public = key_load_public(filename, NULL);
1181                 debug("identity file %s type %d", filename,
1182                     public ? public->type : -1);
1183                 xfree(options.identity_files[i]);
1184                 options.identity_files[i] = filename;
1185                 options.identity_keys[i] = public;
1186         }
1187 }