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             /*
 568              * Since the config file parsing code aborts if it sees
 569              * options it doesn't recognize, allow users to put
 570              * options specific to compile-time add-ons in alternate
 571              * config files so their primary config file will
 572              * interoperate SSH versions that don't support those
 573              * options.
 574              */
 575 #ifdef GSSAPI
 576                 snprintf(buf, sizeof buf, "%.100s/%.100s.gssapi", pw->pw_dir,
 577                     _PATH_SSH_USER_CONFFILE);
 578                 (void)read_config_file(buf, host, &options);
 579 #ifdef GSI
 580                 snprintf(buf, sizeof buf, "%.100s/%.100s.gsi", pw->pw_dir,
 581                     _PATH_SSH_USER_CONFFILE);
 582                 (void)read_config_file(buf, host, &options);
 583 #endif
 584 #if defined(KRB5)
 585                 snprintf(buf, sizeof buf, "%.100s/%.100s.krb", pw->pw_dir,
 586                     _PATH_SSH_USER_CONFFILE);
 587                 (void)read_config_file(buf, host, &options);
 588 #endif
 589 #endif
 590                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 591                     _PATH_SSH_USER_CONFFILE);
 592                 (void)read_config_file(buf, host, &options);
 593
 594                 /* Read systemwide configuration file after use config. */
 595                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
 596         }
 597
 598         /* Fill configuration defaults. */
 599         fill_default_options(&options);
 600
 601         channel_set_af(options.address_family);
 602
 603         /* reinit */
 604         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 605
 606         seed_rng();
 607
 608         if (options.user == NULL) {
 609                 options.user = xstrdup(pw->pw_name);
 610                 options.implicit = 1;
 611         }
 612         else options.implicit = 0;
 613
 614         if (options.hostname != NULL)
 615                 host = options.hostname;
 616
 617         /* force lowercase for hostkey matching */
 618         if (options.host_key_alias != NULL) {
 619                 for (p = options.host_key_alias; *p; p++)
 620                         if (isupper(*p))
 621                                 *p = tolower(*p);
 622         }
 623
 624         if (options.proxy_command != NULL &&
 625             strcmp(options.proxy_command, "none") == 0)
 626                 options.proxy_command = NULL;
 627
 628         /* Open a connection to the remote host. */
 629         if (ssh_connect(host, &hostaddr, options.port,
 630             options.address_family, options.connection_attempts,
 631 #ifdef HAVE_CYGWIN
 632             options.use_privileged_port,
 633 #else
 634             original_effective_uid == 0 && options.use_privileged_port,
 635 #endif
 636             options.proxy_command) != 0)
 637                 exit(1);
 638
 639         /*
 640          * If we successfully made the connection, load the host private key
 641          * in case we will need it later for combined rsa-rhosts
 642          * authentication. This must be done before releasing extra
 643          * privileges, because the file is only readable by root.
 644          * If we cannot access the private keys, load the public keys
 645          * instead and try to execute the ssh-keysign helper instead.
 646          */
 647         sensitive_data.nkeys = 0;
 648         sensitive_data.keys = NULL;
 649         sensitive_data.external_keysign = 0;
 650         if (options.rhosts_rsa_authentication ||
 651             options.hostbased_authentication) {
 652                 sensitive_data.nkeys = 3;
 653                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 654                     sizeof(Key));
 655
 656                 PRIV_START;
 657                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 658                     _PATH_HOST_KEY_FILE, "", NULL);
 659                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 660                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 661                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 662                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 663                 PRIV_END;
 664
 665                 if (options.hostbased_authentication == 1 &&
 666                     sensitive_data.keys[0] == NULL &&
 667                     sensitive_data.keys[1] == NULL &&
 668                     sensitive_data.keys[2] == NULL) {
 669                         sensitive_data.keys[1] = key_load_public(
 670                             _PATH_HOST_DSA_KEY_FILE, NULL);
 671                         sensitive_data.keys[2] = key_load_public(
 672                             _PATH_HOST_RSA_KEY_FILE, NULL);
 673                         sensitive_data.external_keysign = 1;
 674                 }
 675         }
 676         /*
 677          * Get rid of any extra privileges that we may have.  We will no
 678          * longer need them.  Also, extra privileges could make it very hard
 679          * to read identity files and other non-world-readable files from the
 680          * user's home directory if it happens to be on a NFS volume where
 681          * root is mapped to nobody.
 682          */
 683         seteuid(original_real_uid);
 684         setuid(original_real_uid);
 685
 686         /*
 687          * Now that we are back to our own permissions, create ~/.ssh
 688          * directory if it doesn\'t already exist.
 689          */
 690         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 691         if (stat(buf, &st) < 0)
 692                 if (mkdir(buf, 0700) < 0)
 693                         error("Could not create directory '%.200s'.", buf);
 694
 695         /* load options.identity_files */
 696         load_public_identity_files();
 697
 698         /* Expand ~ in known host file names. */
 699         /* XXX mem-leaks: */
 700         options.system_hostfile =
 701             tilde_expand_filename(options.system_hostfile, original_real_uid);
 702         options.user_hostfile =
 703             tilde_expand_filename(options.user_hostfile, original_real_uid);
 704         options.system_hostfile2 =
 705             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 706         options.user_hostfile2 =
 707             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 708
 709         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 710
 711         /* Log into the remote system.  This never returns if the login fails. */
 712         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 713
 714         /* We no longer need the private host keys.  Clear them now. */
 715         if (sensitive_data.nkeys != 0) {
 716                 for (i = 0; i < sensitive_data.nkeys; i++) {
 717                         if (sensitive_data.keys[i] != NULL) {
 718                                 /* Destroys contents safely */
 719                                 debug3("clear hostkey %d", i);
 720                                 key_free(sensitive_data.keys[i]);
 721                                 sensitive_data.keys[i] = NULL;
 722                         }
 723                 }
 724                 xfree(sensitive_data.keys);
 725         }
 726         for (i = 0; i < options.num_identity_files; i++) {
 727                 if (options.identity_files[i]) {
 728                         xfree(options.identity_files[i]);
 729                         options.identity_files[i] = NULL;
 730                 }
 731                 if (options.identity_keys[i]) {
 732                         key_free(options.identity_keys[i]);
 733                         options.identity_keys[i] = NULL;
 734                 }
 735         }
 736
 737         exit_status = compat20 ? ssh_session2() : ssh_session();
 738         packet_close();
 739
 740         /*
 741          * Send SIGHUP to proxy command if used. We don't wait() in
 742          * case it hangs and instead rely on init to reap the child
 743          */
 744         if (proxy_command_pid > 1)
 745                 kill(proxy_command_pid, SIGHUP);
 746
 747         return exit_status;
 748 }
 749
 750 static void
 751 x11_get_proto(char **_proto, char **_data)
 752 {
 753         char line[512];
 754         static char proto[512], data[512];
 755         FILE *f;
 756         int got_data = 0, i;
 757         char *display;
 758         struct stat st;
 759
 760         *_proto = proto;
 761         *_data = data;
 762         proto[0] = data[0] = '\0';
 763         if (!options.xauth_location ||
 764             (stat(options.xauth_location, &st) == -1)) {
 765                 debug("No xauth program.");
 766         } else {
 767                 if ((display = getenv("DISPLAY")) == NULL) {
 768                         debug("x11_get_proto: DISPLAY not set");
 769                         return;
 770                 }
 771                 /* Try to get Xauthority information for the display. */
 772                 if (strncmp(display, "localhost:", 10) == 0)
 773                         /*
 774                          * Handle FamilyLocal case where $DISPLAY does
 775                          * not match an authorization entry.  For this we
 776                          * just try "xauth list unix:displaynum.screennum".
 777                          * XXX: "localhost" match to determine FamilyLocal
 778                          *      is not perfect.
 779                          */
 780                         snprintf(line, sizeof line, "%s list unix:%s 2>"
 781                             _PATH_DEVNULL, options.xauth_location, display+10);
 782                 else
 783                         snprintf(line, sizeof line, "%s list %.200s 2>"
 784                             _PATH_DEVNULL, options.xauth_location, display);
 785                 debug2("x11_get_proto: %s", line);
 786                 f = popen(line, "r");
 787                 if (f && fgets(line, sizeof(line), f) &&
 788                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 789                         got_data = 1;
 790                 if (f)
 791                         pclose(f);
 792         }
 793         /*
 794          * If we didn't get authentication data, just make up some
 795          * data.  The forwarding code will check the validity of the
 796          * response anyway, and substitute this data.  The X11
 797          * server, however, will ignore this fake data and use
 798          * whatever authentication mechanisms it was using otherwise
 799          * for the local connection.
 800          */
 801         if (!got_data) {
 802                 u_int32_t rand = 0;
 803
 804                 logit("Warning: No xauth data; using fake authentication data for X11 forwarding.");
 805                 strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
 806                 for (i = 0; i < 16; i++) {
 807                         if (i % 4 == 0)
 808                                 rand = arc4random();
 809                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
 810                         rand >>= 8;
 811                 }
 812         }
 813 }
 814
 815 static void
 816 ssh_init_forwarding(void)
 817 {
 818         int success = 0;
 819         int i;
 820
 821         /* Initiate local TCP/IP port forwardings. */
 822         for (i = 0; i < options.num_local_forwards; i++) {
 823                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
 824                     options.local_forwards[i].port,
 825                     options.local_forwards[i].host,
 826                     options.local_forwards[i].host_port);
 827                 success += channel_setup_local_fwd_listener(
 828                     options.local_forwards[i].port,
 829                     options.local_forwards[i].host,
 830                     options.local_forwards[i].host_port,
 831                     options.gateway_ports);
 832         }
 833         if (i > 0 && success == 0)
 834                 error("Could not request local forwarding.");
 835
 836         /* Initiate remote TCP/IP port forwardings. */
 837         for (i = 0; i < options.num_remote_forwards; i++) {
 838                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
 839                     options.remote_forwards[i].port,
 840                     options.remote_forwards[i].host,
 841                     options.remote_forwards[i].host_port);
 842                 channel_request_remote_forwarding(
 843                     options.remote_forwards[i].port,
 844                     options.remote_forwards[i].host,
 845                     options.remote_forwards[i].host_port);
 846         }
 847 }
 848
 849 static void
 850 check_agent_present(void)
 851 {
 852         if (options.forward_agent) {
 853                 /* Clear agent forwarding if we don\'t have an agent. */
 854                 if (!ssh_agent_present())
 855                         options.forward_agent = 0;
 856         }
 857 }
 858
 859 static int
 860 ssh_session(void)
 861 {
 862         int type;
 863         int interactive = 0;
 864         int have_tty = 0;
 865         struct winsize ws;
 866         char *cp;
 867
 868         /* Enable compression if requested. */
 869         if (options.compression) {
 870                 debug("Requesting compression at level %d.", options.compression_level);
 871
 872                 if (options.compression_level < 1 || options.compression_level > 9)
 873                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 874
 875                 /* Send the request. */
 876                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 877                 packet_put_int(options.compression_level);
 878                 packet_send();
 879                 packet_write_wait();
 880                 type = packet_read();
 881                 if (type == SSH_SMSG_SUCCESS)
 882                         packet_start_compression(options.compression_level);
 883                 else if (type == SSH_SMSG_FAILURE)
 884                         logit("Warning: Remote host refused compression.");
 885                 else
 886                         packet_disconnect("Protocol error waiting for compression response.");
 887         }
 888         /* Allocate a pseudo tty if appropriate. */
 889         if (tty_flag) {
 890                 debug("Requesting pty.");
 891
 892                 /* Start the packet. */
 893                 packet_start(SSH_CMSG_REQUEST_PTY);
 894
 895                 /* Store TERM in the packet.  There is no limit on the
 896                    length of the string. */
 897                 cp = getenv("TERM");
 898                 if (!cp)
 899                         cp = "";
 900                 packet_put_cstring(cp);
 901
 902                 /* Store window size in the packet. */
 903                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 904                         memset(&ws, 0, sizeof(ws));
 905                 packet_put_int(ws.ws_row);
 906                 packet_put_int(ws.ws_col);
 907                 packet_put_int(ws.ws_xpixel);
 908                 packet_put_int(ws.ws_ypixel);
 909
 910                 /* Store tty modes in the packet. */
 911                 tty_make_modes(fileno(stdin), NULL);
 912
 913                 /* Send the packet, and wait for it to leave. */
 914                 packet_send();
 915                 packet_write_wait();
 916
 917                 /* Read response from the server. */
 918                 type = packet_read();
 919                 if (type == SSH_SMSG_SUCCESS) {
 920                         interactive = 1;
 921                         have_tty = 1;
 922                 } else if (type == SSH_SMSG_FAILURE)
 923                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 924                 else
 925                         packet_disconnect("Protocol error waiting for pty request response.");
 926         }
 927         /* Request X11 forwarding if enabled and DISPLAY is set. */
 928         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 929                 char *proto, *data;
 930                 /* Get reasonable local authentication information. */
 931                 x11_get_proto(&proto, &data);
 932                 /* Request forwarding with authentication spoofing. */
 933                 debug("Requesting X11 forwarding with authentication spoofing.");
 934                 x11_request_forwarding_with_spoofing(0, proto, data);
 935
 936                 /* Read response from the server. */
 937                 type = packet_read();
 938                 if (type == SSH_SMSG_SUCCESS) {
 939                         interactive = 1;
 940                 } else if (type == SSH_SMSG_FAILURE) {
 941                         logit("Warning: Remote host denied X11 forwarding.");
 942                 } else {
 943                         packet_disconnect("Protocol error waiting for X11 forwarding");
 944                 }
 945         }
 946         /* Tell the packet module whether this is an interactive session. */
 947         packet_set_interactive(interactive);
 948
 949         /* Request authentication agent forwarding if appropriate. */
 950         check_agent_present();
 951
 952         if (options.forward_agent) {
 953                 debug("Requesting authentication agent forwarding.");
 954                 auth_request_forwarding();
 955
 956                 /* Read response from the server. */
 957                 type = packet_read();
 958                 packet_check_eom();
 959                 if (type != SSH_SMSG_SUCCESS)
 960                         logit("Warning: Remote host denied authentication agent forwarding.");
 961         }
 962
 963         /* Initiate port forwardings. */
 964         ssh_init_forwarding();
 965
 966         /* If requested, let ssh continue in the background. */
 967         if (fork_after_authentication_flag)
 968                 if (daemon(1, 1) < 0)
 969                         fatal("daemon() failed: %.200s", strerror(errno));
 970
 971         /*
 972          * If a command was specified on the command line, execute the
 973          * command now. Otherwise request the server to start a shell.
 974          */
 975         if (buffer_len(&command) > 0) {
 976                 int len = buffer_len(&command);
 977                 if (len > 900)
 978                         len = 900;
 979                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 980                 packet_start(SSH_CMSG_EXEC_CMD);
 981                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 982                 packet_send();
 983                 packet_write_wait();
 984         } else {
 985                 debug("Requesting shell.");
 986                 packet_start(SSH_CMSG_EXEC_SHELL);
 987                 packet_send();
 988                 packet_write_wait();
 989         }
 990
 991         /* Enter the interactive session. */
 992         return client_loop(have_tty, tty_flag ?
 993             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
 994 }
 995
 996 static void
 997 client_subsystem_reply(int type, u_int32_t seq, void *ctxt)
 998 {
 999         int id, len;
1000
1001         id = packet_get_int();
1002         len = buffer_len(&command);
1003         if (len > 900)
1004                 len = 900;
1005         packet_check_eom();
1006         if (type == SSH2_MSG_CHANNEL_FAILURE)
1007                 fatal("Request for subsystem '%.*s' failed on channel %d",
1008                     len, (u_char *)buffer_ptr(&command), id);
1009 }
1010
1011 void
1012 client_global_request_reply(int type, u_int32_t seq, void *ctxt)
1013 {
1014         int i;
1015
1016         i = client_global_request_id++;
1017         if (i >= options.num_remote_forwards) {
1018                 debug("client_global_request_reply: too many replies %d > %d",
1019                     i, options.num_remote_forwards);
1020                 return;
1021         }
1022         debug("remote forward %s for: listen %d, connect %s:%d",
1023             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1024             options.remote_forwards[i].port,
1025             options.remote_forwards[i].host,
1026             options.remote_forwards[i].host_port);
1027         if (type == SSH2_MSG_REQUEST_FAILURE)
1028                 logit("Warning: remote port forwarding failed for listen port %d",
1029                     options.remote_forwards[i].port);
1030 }
1031
1032 /* request pty/x11/agent/tcpfwd/shell for channel */
1033 static void
1034 ssh_session2_setup(int id, void *arg)
1035 {
1036         int len;
1037         int interactive = 0;
1038         struct termios tio;
1039
1040         debug2("ssh_session2_setup: id %d", id);
1041
1042         if (tty_flag) {
1043                 struct winsize ws;
1044                 char *cp;
1045                 cp = getenv("TERM");
1046                 if (!cp)
1047                         cp = "";
1048                 /* Store window size in the packet. */
1049                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1050                         memset(&ws, 0, sizeof(ws));
1051
1052                 channel_request_start(id, "pty-req", 0);
1053                 packet_put_cstring(cp);
1054                 packet_put_int(ws.ws_col);
1055                 packet_put_int(ws.ws_row);
1056                 packet_put_int(ws.ws_xpixel);
1057                 packet_put_int(ws.ws_ypixel);
1058                 tio = get_saved_tio();
1059                 tty_make_modes(/*ignored*/ 0, &tio);
1060                 packet_send();
1061                 interactive = 1;
1062                 /* XXX wait for reply */
1063         }
1064         if (options.forward_x11 &&
1065             getenv("DISPLAY") != NULL) {
1066                 char *proto, *data;
1067                 /* Get reasonable local authentication information. */
1068                 x11_get_proto(&proto, &data);
1069                 /* Request forwarding with authentication spoofing. */
1070                 debug("Requesting X11 forwarding with authentication spoofing.");
1071                 x11_request_forwarding_with_spoofing(id, proto, data);
1072                 interactive = 1;
1073                 /* XXX wait for reply */
1074         }
1075
1076         check_agent_present();
1077         if (options.forward_agent) {
1078                 debug("Requesting authentication agent forwarding.");
1079                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1080                 packet_send();
1081         }
1082
1083         len = buffer_len(&command);
1084         if (len > 0) {
1085                 if (len > 900)
1086                         len = 900;
1087                 if (subsystem_flag) {
1088                         debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command));
1089                         channel_request_start(id, "subsystem", /*want reply*/ 1);
1090                         /* register callback for reply */
1091                         /* XXX we assume that client_loop has already been called */
1092                         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
1093                         dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1094                 } else {
1095                         debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1096                         channel_request_start(id, "exec", 0);
1097                 }
1098                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1099                 packet_send();
1100         } else {
1101                 channel_request_start(id, "shell", 0);
1102                 packet_send();
1103         }
1104
1105         packet_set_interactive(interactive);
1106 }
1107
1108 /* open new channel for a session */
1109 static int
1110 ssh_session2_open(void)
1111 {
1112         Channel *c;
1113         int window, packetmax, in, out, err;
1114
1115         if (stdin_null_flag) {
1116                 in = open(_PATH_DEVNULL, O_RDONLY);
1117         } else {
1118                 in = dup(STDIN_FILENO);
1119         }
1120         out = dup(STDOUT_FILENO);
1121         err = dup(STDERR_FILENO);
1122
1123         if (in < 0 || out < 0 || err < 0)
1124                 fatal("dup() in/out/err failed");
1125
1126         /* enable nonblocking unless tty */
1127         if (!isatty(in))
1128                 set_nonblock(in);
1129         if (!isatty(out))
1130                 set_nonblock(out);
1131         if (!isatty(err))
1132                 set_nonblock(err);
1133
1134         window = CHAN_SES_WINDOW_DEFAULT;
1135         packetmax = CHAN_SES_PACKET_DEFAULT;
1136         if (tty_flag) {
1137                 window >>= 1;
1138                 packetmax >>= 1;
1139         }
1140         c = channel_new(
1141             "session", SSH_CHANNEL_OPENING, in, out, err,
1142             window, packetmax, CHAN_EXTENDED_WRITE,
1143             "client-session", /*nonblock*/0);
1144
1145         debug3("ssh_session2_open: channel_new: %d", c->self);
1146
1147         channel_send_open(c->self);
1148         if (!no_shell_flag)
1149                 channel_register_confirm(c->self, ssh_session2_setup);
1150
1151         return c->self;
1152 }
1153
1154 static int
1155 ssh_session2(void)
1156 {
1157         int id = -1;
1158
1159         /* XXX should be pre-session */
1160         ssh_init_forwarding();
1161
1162         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1163                 id = ssh_session2_open();
1164
1165         /* If requested, let ssh continue in the background. */
1166         if (fork_after_authentication_flag)
1167                 if (daemon(1, 1) < 0)
1168                         fatal("daemon() failed: %.200s", strerror(errno));
1169
1170         return client_loop(tty_flag, tty_flag ?
1171             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1172 }
1173
1174 static void
1175 load_public_identity_files(void)
1176 {
1177         char *filename;
1178         int i = 0;
1179         Key *public;
1180 #ifdef SMARTCARD
1181         Key **keys;
1182
1183         if (options.smartcard_device != NULL &&
1184             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1185             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1186                 int count = 0;
1187                 for (i = 0; keys[i] != NULL; i++) {
1188                         count++;
1189                         memmove(&options.identity_files[1], &options.identity_files[0],
1190                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1191                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1192                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1193                         options.num_identity_files++;
1194                         options.identity_keys[0] = keys[i];
1195                         options.identity_files[0] = sc_get_key_label(keys[i]);
1196                 }
1197                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1198                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1199                 i = count;
1200                 xfree(keys);
1201         }
1202 #endif /* SMARTCARD */
1203         for (; i < options.num_identity_files; i++) {
1204                 filename = tilde_expand_filename(options.identity_files[i],
1205                     original_real_uid);
1206                 public = key_load_public(filename, NULL);
1207                 debug("identity file %s type %d", filename,
1208                     public ? public->type : -1);
1209                 xfree(options.identity_files[i]);
1210                 options.identity_files[i] = filename;
1211                 options.identity_keys[i] = public;
1212         }
1213 }