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_pathnames();
 216         init_rng();
 217
 218         /*
 219          * Save the original real uid.  It will be needed later (uid-swapping
 220          * may clobber the real uid).
 221          */
 222         original_real_uid = getuid();
 223         original_effective_uid = geteuid();
 224
 225         /*
 226          * Use uid-swapping to give up root privileges for the duration of
 227          * option processing.  We will re-instantiate the rights when we are
 228          * ready to create the privileged port, and will permanently drop
 229          * them when the port has been created (actually, when the connection
 230          * has been made, as we may need to create the port several times).
 231          */
 232         PRIV_END;
 233
 234 #ifdef HAVE_SETRLIMIT
 235         /* If we are installed setuid root be careful to not drop core. */
 236         if (original_real_uid != original_effective_uid) {
 237                 struct rlimit rlim;
 238                 rlim.rlim_cur = rlim.rlim_max = 0;
 239                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 240                         fatal("setrlimit failed: %.100s", strerror(errno));
 241         }
 242 #endif
 243         /* Get user data. */
 244         pw = getpwuid(original_real_uid);
 245         if (!pw) {
 246                 logit("You don't exist, go away!");
 247                 exit(1);
 248         }
 249         /* Take a copy of the returned structure. */
 250         pw = pwcopy(pw);
 251
 252         /*
 253          * Set our umask to something reasonable, as some files are created
 254          * with the default umask.  This will make them world-readable but
 255          * writable only by the owner, which is ok for all files for which we
 256          * don't set the modes explicitly.
 257          */
 258         umask(022);
 259
 260         /* Initialize option structure to indicate that no values have been set. */
 261         initialize_options(&options);
 262
 263         /* Parse command-line arguments. */
 264         host = NULL;
 265
 266 again:
 267         while ((opt = getopt(ac, av,
 268             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVX")) != -1) {
 269                 switch (opt) {
 270                 case '1':
 271                         options.protocol = SSH_PROTO_1;
 272                         break;
 273                 case '2':
 274                         options.protocol = SSH_PROTO_2;
 275                         break;
 276                 case '4':
 277                         options.address_family = AF_INET;
 278                         break;
 279                 case '6':
 280                         options.address_family = AF_INET6;
 281                         break;
 282                 case 'n':
 283                         stdin_null_flag = 1;
 284                         break;
 285                 case 'f':
 286                         fork_after_authentication_flag = 1;
 287                         stdin_null_flag = 1;
 288                         break;
 289                 case 'x':
 290                         options.forward_x11 = 0;
 291                         break;
 292                 case 'X':
 293                         options.forward_x11 = 1;
 294                         break;
 295                 case 'g':
 296                         options.gateway_ports = 1;
 297                         break;
 298                 case 'P':       /* deprecated */
 299                         options.use_privileged_port = 0;
 300                         break;
 301                 case 'a':
 302                         options.forward_agent = 0;
 303                         break;
 304                 case 'A':
 305                         options.forward_agent = 1;
 306                         break;
 307                 case 'k':
 308                         /* ignored for backward compatibility */
 309                         break;
 310                 case 'i':
 311                         if (stat(optarg, &st) < 0) {
 312                                 fprintf(stderr, "Warning: Identity file %s "
 313                                     "does not exist.\n", optarg);
 314                                 break;
 315                         }
 316                         if (options.num_identity_files >=
 317                             SSH_MAX_IDENTITY_FILES)
 318                                 fatal("Too many identity files specified "
 319                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 320                         options.identity_files[options.num_identity_files++] =
 321                             xstrdup(optarg);
 322                         break;
 323                 case 'I':
 324 #ifdef SMARTCARD
 325                         options.smartcard_device = xstrdup(optarg);
 326 #else
 327                         fprintf(stderr, "no support for smartcards.\n");
 328 #endif
 329                         break;
 330                 case 't':
 331                         if (tty_flag)
 332                                 force_tty_flag = 1;
 333                         tty_flag = 1;
 334                         break;
 335                 case 'v':
 336                         if (debug_flag == 0) {
 337                                 debug_flag = 1;
 338                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 339                         } else {
 340                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 341                                         options.log_level++;
 342                                 break;
 343                         }
 344                         /* fallthrough */
 345                 case 'V':
 346                         fprintf(stderr,
 347                             "%s, SSH protocols %d.%d/%d.%d, %s\n",
 348                             SSH_VERSION,
 349                             PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
 350                             PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
 351                             SSLeay_version(SSLEAY_VERSION));
 352                         if (opt == 'V')
 353                                 exit(0);
 354                         break;
 355                 case 'q':
 356                         options.log_level = SYSLOG_LEVEL_QUIET;
 357                         break;
 358                 case 'e':
 359                         if (optarg[0] == '^' && optarg[2] == 0 &&
 360                             (u_char) optarg[1] >= 64 &&
 361                             (u_char) optarg[1] < 128)
 362                                 options.escape_char = (u_char) optarg[1] & 31;
 363                         else if (strlen(optarg) == 1)
 364                                 options.escape_char = (u_char) optarg[0];
 365                         else if (strcmp(optarg, "none") == 0)
 366                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 367                         else {
 368                                 fprintf(stderr, "Bad escape character '%s'.\n",
 369                                     optarg);
 370                                 exit(1);
 371                         }
 372                         break;
 373                 case 'c':
 374                         if (ciphers_valid(optarg)) {
 375                                 /* SSH2 only */
 376                                 options.ciphers = xstrdup(optarg);
 377                                 options.cipher = SSH_CIPHER_ILLEGAL;
 378                         } else {
 379                                 /* SSH1 only */
 380                                 options.cipher = cipher_number(optarg);
 381                                 if (options.cipher == -1) {
 382                                         fprintf(stderr,
 383                                             "Unknown cipher type '%s'\n",
 384                                             optarg);
 385                                         exit(1);
 386                                 }
 387                                 if (options.cipher == SSH_CIPHER_3DES)
 388                                         options.ciphers = "3des-cbc";
 389                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 390                                         options.ciphers = "blowfish-cbc";
 391                                 else
 392                                         options.ciphers = (char *)-1;
 393                         }
 394                         break;
 395                 case 'm':
 396                         if (mac_valid(optarg))
 397                                 options.macs = xstrdup(optarg);
 398                         else {
 399                                 fprintf(stderr, "Unknown mac type '%s'\n",
 400                                     optarg);
 401                                 exit(1);
 402                         }
 403                         break;
 404                 case 'p':
 405                         options.port = a2port(optarg);
 406                         if (options.port == 0) {
 407                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 408                                 exit(1);
 409                         }
 410                         break;
 411                 case 'l':
 412                         options.user = optarg;
 413                         break;
 414
 415                 case 'L':
 416                 case 'R':
 417                         if (sscanf(optarg, "%5[0123456789]:%255[^:]:%5[0123456789]",
 418                             sfwd_port, buf, sfwd_host_port) != 3 &&
 419                             sscanf(optarg, "%5[0123456789]/%255[^/]/%5[0123456789]",
 420                             sfwd_port, buf, sfwd_host_port) != 3) {
 421                                 fprintf(stderr,
 422                                     "Bad forwarding specification '%s'\n",
 423                                     optarg);
 424                                 usage();
 425                                 /* NOTREACHED */
 426                         }
 427                         if ((fwd_port = a2port(sfwd_port)) == 0 ||
 428                             (fwd_host_port = a2port(sfwd_host_port)) == 0) {
 429                                 fprintf(stderr,
 430                                     "Bad forwarding port(s) '%s'\n", optarg);
 431                                 exit(1);
 432                         }
 433                         if (opt == 'L')
 434                                 add_local_forward(&options, fwd_port, buf,
 435                                     fwd_host_port);
 436                         else if (opt == 'R')
 437                                 add_remote_forward(&options, fwd_port, buf,
 438                                     fwd_host_port);
 439                         break;
 440
 441                 case 'D':
 442                         fwd_port = a2port(optarg);
 443                         if (fwd_port == 0) {
 444                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 445                                     optarg);
 446                                 exit(1);
 447                         }
 448                         add_local_forward(&options, fwd_port, "socks", 0);
 449                         break;
 450
 451                 case 'C':
 452                         options.compression = 1;
 453                         break;
 454                 case 'N':
 455                         no_shell_flag = 1;
 456                         no_tty_flag = 1;
 457                         break;
 458                 case 'T':
 459                         no_tty_flag = 1;
 460                         break;
 461                 case 'o':
 462                         dummy = 1;
 463                         if (process_config_line(&options, host ? host : "",
 464                             optarg, "command-line", 0, &dummy) != 0)
 465                                 exit(1);
 466                         break;
 467                 case 's':
 468                         subsystem_flag = 1;
 469                         break;
 470                 case 'b':
 471                         options.bind_address = optarg;
 472                         break;
 473                 case 'F':
 474                         config = optarg;
 475                         break;
 476                 default:
 477                         usage();
 478                 }
 479         }
 480
 481         ac -= optind;
 482         av += optind;
 483
 484         if (ac > 0 && !host && **av != '-') {
 485                 if (strrchr(*av, '@')) {
 486                         p = xstrdup(*av);
 487                         cp = strrchr(p, '@');
 488                         if (cp == NULL || cp == p)
 489                                 usage();
 490                         options.user = p;
 491                         *cp = '\0';
 492                         host = ++cp;
 493                 } else
 494                         host = *av;
 495                 if (ac > 1) {
 496                         optind = optreset = 1;
 497                         goto again;
 498                 }
 499                 ac--, av++;
 500         }
 501
 502         /* Check that we got a host name. */
 503         if (!host)
 504                 usage();
 505
 506         SSLeay_add_all_algorithms();
 507         ERR_load_crypto_strings();
 508
 509         /* Initialize the command to execute on remote host. */
 510         buffer_init(&command);
 511
 512         /*
 513          * Save the command to execute on the remote host in a buffer. There
 514          * is no limit on the length of the command, except by the maximum
 515          * packet size.  Also sets the tty flag if there is no command.
 516          */
 517         if (!ac) {
 518                 /* No command specified - execute shell on a tty. */
 519                 tty_flag = 1;
 520                 if (subsystem_flag) {
 521                         fprintf(stderr,
 522                             "You must specify a subsystem to invoke.\n");
 523                         usage();
 524                 }
 525         } else {
 526                 /* A command has been specified.  Store it into the buffer. */
 527                 for (i = 0; i < ac; i++) {
 528                         if (i)
 529                                 buffer_append(&command, " ", 1);
 530                         buffer_append(&command, av[i], strlen(av[i]));
 531                 }
 532         }
 533
 534         /* Cannot fork to background if no command. */
 535         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 536                 fatal("Cannot fork into background without a command to execute.");
 537
 538         /* Allocate a tty by default if no command specified. */
 539         if (buffer_len(&command) == 0)
 540                 tty_flag = 1;
 541
 542         /* Force no tty */
 543         if (no_tty_flag)
 544                 tty_flag = 0;
 545         /* Do not allocate a tty if stdin is not a tty. */
 546         if (!isatty(fileno(stdin)) && !force_tty_flag) {
 547                 if (tty_flag)
 548                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 549                 tty_flag = 0;
 550         }
 551
 552         /*
 553          * Initialize "log" output.  Since we are the client all output
 554          * actually goes to stderr.
 555          */
 556         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 557             SYSLOG_FACILITY_USER, 1);
 558
 559         /*
 560          * Read per-user configuration file.  Ignore the system wide config
 561          * file if the user specifies a config file on the command line.
 562          */
 563         if (config != NULL) {
 564                 if (!read_config_file(config, host, &options))
 565                         fatal("Can't open user config file %.100s: "
 566                             "%.100s", config, strerror(errno));
 567         } else  {
 568             /*
 569              * Since the config file parsing code aborts if it sees
 570              * options it doesn't recognize, allow users to put
 571              * options specific to compile-time add-ons in alternate
 572              * config files so their primary config file will
 573              * interoperate SSH versions that don't support those
 574              * options.
 575              */
 576 #ifdef GSSAPI
 577                 snprintf(buf, sizeof buf, "%.100s/%.100s.gssapi", pw->pw_dir,
 578                     _PATH_SSH_USER_CONFFILE);
 579                 (void)read_config_file(buf, host, &options);
 580 #ifdef GSI
 581                 snprintf(buf, sizeof buf, "%.100s/%.100s.gsi", pw->pw_dir,
 582                     _PATH_SSH_USER_CONFFILE);
 583                 (void)read_config_file(buf, host, &options);
 584 #endif
 585 #if defined(KRB5)
 586                 snprintf(buf, sizeof buf, "%.100s/%.100s.krb", pw->pw_dir,
 587                     _PATH_SSH_USER_CONFFILE);
 588                 (void)read_config_file(buf, host, &options);
 589 #endif
 590 #endif
 591                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 592                     _PATH_SSH_USER_CONFFILE);
 593                 (void)read_config_file(buf, host, &options);
 594
 595                 /* Read systemwide configuration file after use config. */
 596                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
 597         }
 598
 599         /* Fill configuration defaults. */
 600         fill_default_options(&options);
 601
 602         channel_set_af(options.address_family);
 603
 604         /* reinit */
 605         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 606
 607         seed_rng();
 608
 609         if (options.user == NULL) {
 610                 options.user = xstrdup(pw->pw_name);
 611                 options.implicit = 1;
 612         }
 613         else options.implicit = 0;
 614
 615         if (options.hostname != NULL)
 616                 host = options.hostname;
 617
 618         /* force lowercase for hostkey matching */
 619         if (options.host_key_alias != NULL) {
 620                 for (p = options.host_key_alias; *p; p++)
 621                         if (isupper(*p))
 622                                 *p = tolower(*p);
 623         }
 624
 625         if (options.proxy_command != NULL &&
 626             strcmp(options.proxy_command, "none") == 0)
 627                 options.proxy_command = NULL;
 628
 629         /* Open a connection to the remote host. */
 630         if (ssh_connect(host, &hostaddr, options.port,
 631             options.address_family, options.connection_attempts,
 632 #ifdef HAVE_CYGWIN
 633             options.use_privileged_port,
 634 #else
 635             original_effective_uid == 0 && options.use_privileged_port,
 636 #endif
 637             options.proxy_command) != 0)
 638                 exit(1);
 639
 640         /*
 641          * If we successfully made the connection, load the host private key
 642          * in case we will need it later for combined rsa-rhosts
 643          * authentication. This must be done before releasing extra
 644          * privileges, because the file is only readable by root.
 645          * If we cannot access the private keys, load the public keys
 646          * instead and try to execute the ssh-keysign helper instead.
 647          */
 648         sensitive_data.nkeys = 0;
 649         sensitive_data.keys = NULL;
 650         sensitive_data.external_keysign = 0;
 651         if (options.rhosts_rsa_authentication ||
 652             options.hostbased_authentication) {
 653                 sensitive_data.nkeys = 3;
 654                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 655                     sizeof(Key));
 656
 657                 PRIV_START;
 658                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 659                     _PATH_HOST_KEY_FILE, "", NULL);
 660                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 661                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 662                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 663                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 664                 PRIV_END;
 665
 666                 if (options.hostbased_authentication == 1 &&
 667                     sensitive_data.keys[0] == NULL &&
 668                     sensitive_data.keys[1] == NULL &&
 669                     sensitive_data.keys[2] == NULL) {
 670                         sensitive_data.keys[1] = key_load_public(
 671                             _PATH_HOST_DSA_KEY_FILE, NULL);
 672                         sensitive_data.keys[2] = key_load_public(
 673                             _PATH_HOST_RSA_KEY_FILE, NULL);
 674                         sensitive_data.external_keysign = 1;
 675                 }
 676         }
 677         /*
 678          * Get rid of any extra privileges that we may have.  We will no
 679          * longer need them.  Also, extra privileges could make it very hard
 680          * to read identity files and other non-world-readable files from the
 681          * user's home directory if it happens to be on a NFS volume where
 682          * root is mapped to nobody.
 683          */
 684         seteuid(original_real_uid);
 685         setuid(original_real_uid);
 686
 687         /*
 688          * Now that we are back to our own permissions, create ~/.ssh
 689          * directory if it doesn\'t already exist.
 690          */
 691         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 692         if (stat(buf, &st) < 0)
 693                 if (mkdir(buf, 0700) < 0)
 694                         error("Could not create directory '%.200s'.", buf);
 695
 696         /* load options.identity_files */
 697         load_public_identity_files();
 698
 699         /* Expand ~ in known host file names. */
 700         /* XXX mem-leaks: */
 701         options.system_hostfile =
 702             tilde_expand_filename(options.system_hostfile, original_real_uid);
 703         options.user_hostfile =
 704             tilde_expand_filename(options.user_hostfile, original_real_uid);
 705         options.system_hostfile2 =
 706             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 707         options.user_hostfile2 =
 708             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 709
 710         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 711
 712         /* Log into the remote system.  This never returns if the login fails. */
 713         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 714
 715         /* We no longer need the private host keys.  Clear them now. */
 716         if (sensitive_data.nkeys != 0) {
 717                 for (i = 0; i < sensitive_data.nkeys; i++) {
 718                         if (sensitive_data.keys[i] != NULL) {
 719                                 /* Destroys contents safely */
 720                                 debug3("clear hostkey %d", i);
 721                                 key_free(sensitive_data.keys[i]);
 722                                 sensitive_data.keys[i] = NULL;
 723                         }
 724                 }
 725                 xfree(sensitive_data.keys);
 726         }
 727         for (i = 0; i < options.num_identity_files; i++) {
 728                 if (options.identity_files[i]) {
 729                         xfree(options.identity_files[i]);
 730                         options.identity_files[i] = NULL;
 731                 }
 732                 if (options.identity_keys[i]) {
 733                         key_free(options.identity_keys[i]);
 734                         options.identity_keys[i] = NULL;
 735                 }
 736         }
 737
 738         exit_status = compat20 ? ssh_session2() : ssh_session();
 739         packet_close();
 740
 741         /*
 742          * Send SIGHUP to proxy command if used. We don't wait() in
 743          * case it hangs and instead rely on init to reap the child
 744          */
 745         if (proxy_command_pid > 1)
 746                 kill(proxy_command_pid, SIGHUP);
 747
 748         return exit_status;
 749 }
 750
 751 static void
 752 x11_get_proto(char **_proto, char **_data)
 753 {
 754         char line[512];
 755         static char proto[512], data[512];
 756         FILE *f;
 757         int got_data = 0, i;
 758         char *display;
 759         struct stat st;
 760
 761         *_proto = proto;
 762         *_data = data;
 763         proto[0] = data[0] = '\0';
 764         if (!options.xauth_location ||
 765             (stat(options.xauth_location, &st) == -1)) {
 766                 debug("No xauth program.");
 767         } else {
 768                 if ((display = getenv("DISPLAY")) == NULL) {
 769                         debug("x11_get_proto: DISPLAY not set");
 770                         return;
 771                 }
 772                 /* Try to get Xauthority information for the display. */
 773                 if (strncmp(display, "localhost:", 10) == 0)
 774                         /*
 775                          * Handle FamilyLocal case where $DISPLAY does
 776                          * not match an authorization entry.  For this we
 777                          * just try "xauth list unix:displaynum.screennum".
 778                          * XXX: "localhost" match to determine FamilyLocal
 779                          *      is not perfect.
 780                          */
 781                         snprintf(line, sizeof line, "%s list unix:%s 2>"
 782                             _PATH_DEVNULL, options.xauth_location, display+10);
 783                 else
 784                         snprintf(line, sizeof line, "%s list %.200s 2>"
 785                             _PATH_DEVNULL, options.xauth_location, display);
 786                 debug2("x11_get_proto: %s", line);
 787                 f = popen(line, "r");
 788                 if (f && fgets(line, sizeof(line), f) &&
 789                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 790                         got_data = 1;
 791                 if (f)
 792                         pclose(f);
 793         }
 794         /*
 795          * If we didn't get authentication data, just make up some
 796          * data.  The forwarding code will check the validity of the
 797          * response anyway, and substitute this data.  The X11
 798          * server, however, will ignore this fake data and use
 799          * whatever authentication mechanisms it was using otherwise
 800          * for the local connection.
 801          */
 802         if (!got_data) {
 803                 u_int32_t rand = 0;
 804
 805                 logit("Warning: No xauth data; using fake authentication data for X11 forwarding.");
 806                 strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
 807                 for (i = 0; i < 16; i++) {
 808                         if (i % 4 == 0)
 809                                 rand = arc4random();
 810                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
 811                         rand >>= 8;
 812                 }
 813         }
 814 }
 815
 816 static void
 817 ssh_init_forwarding(void)
 818 {
 819         int success = 0;
 820         int i;
 821
 822         /* Initiate local TCP/IP port forwardings. */
 823         for (i = 0; i < options.num_local_forwards; i++) {
 824                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
 825                     options.local_forwards[i].port,
 826                     options.local_forwards[i].host,
 827                     options.local_forwards[i].host_port);
 828                 success += channel_setup_local_fwd_listener(
 829                     options.local_forwards[i].port,
 830                     options.local_forwards[i].host,
 831                     options.local_forwards[i].host_port,
 832                     options.gateway_ports);
 833         }
 834         if (i > 0 && success == 0)
 835                 error("Could not request local forwarding.");
 836
 837         /* Initiate remote TCP/IP port forwardings. */
 838         for (i = 0; i < options.num_remote_forwards; i++) {
 839                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
 840                     options.remote_forwards[i].port,
 841                     options.remote_forwards[i].host,
 842                     options.remote_forwards[i].host_port);
 843                 channel_request_remote_forwarding(
 844                     options.remote_forwards[i].port,
 845                     options.remote_forwards[i].host,
 846                     options.remote_forwards[i].host_port);
 847         }
 848 }
 849
 850 static void
 851 check_agent_present(void)
 852 {
 853         if (options.forward_agent) {
 854                 /* Clear agent forwarding if we don\'t have an agent. */
 855                 if (!ssh_agent_present())
 856                         options.forward_agent = 0;
 857         }
 858 }
 859
 860 static int
 861 ssh_session(void)
 862 {
 863         int type;
 864         int interactive = 0;
 865         int have_tty = 0;
 866         struct winsize ws;
 867         char *cp;
 868
 869         /* Enable compression if requested. */
 870         if (options.compression) {
 871                 debug("Requesting compression at level %d.", options.compression_level);
 872
 873                 if (options.compression_level < 1 || options.compression_level > 9)
 874                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 875
 876                 /* Send the request. */
 877                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 878                 packet_put_int(options.compression_level);
 879                 packet_send();
 880                 packet_write_wait();
 881                 type = packet_read();
 882                 if (type == SSH_SMSG_SUCCESS)
 883                         packet_start_compression(options.compression_level);
 884                 else if (type == SSH_SMSG_FAILURE)
 885                         logit("Warning: Remote host refused compression.");
 886                 else
 887                         packet_disconnect("Protocol error waiting for compression response.");
 888         }
 889         /* Allocate a pseudo tty if appropriate. */
 890         if (tty_flag) {
 891                 debug("Requesting pty.");
 892
 893                 /* Start the packet. */
 894                 packet_start(SSH_CMSG_REQUEST_PTY);
 895
 896                 /* Store TERM in the packet.  There is no limit on the
 897                    length of the string. */
 898                 cp = getenv("TERM");
 899                 if (!cp)
 900                         cp = "";
 901                 packet_put_cstring(cp);
 902
 903                 /* Store window size in the packet. */
 904                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 905                         memset(&ws, 0, sizeof(ws));
 906                 packet_put_int(ws.ws_row);
 907                 packet_put_int(ws.ws_col);
 908                 packet_put_int(ws.ws_xpixel);
 909                 packet_put_int(ws.ws_ypixel);
 910
 911                 /* Store tty modes in the packet. */
 912                 tty_make_modes(fileno(stdin), NULL);
 913
 914                 /* Send the packet, and wait for it to leave. */
 915                 packet_send();
 916                 packet_write_wait();
 917
 918                 /* Read response from the server. */
 919                 type = packet_read();
 920                 if (type == SSH_SMSG_SUCCESS) {
 921                         interactive = 1;
 922                         have_tty = 1;
 923                 } else if (type == SSH_SMSG_FAILURE)
 924                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 925                 else
 926                         packet_disconnect("Protocol error waiting for pty request response.");
 927         }
 928         /* Request X11 forwarding if enabled and DISPLAY is set. */
 929         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 930                 char *proto, *data;
 931                 /* Get reasonable local authentication information. */
 932                 x11_get_proto(&proto, &data);
 933                 /* Request forwarding with authentication spoofing. */
 934                 debug("Requesting X11 forwarding with authentication spoofing.");
 935                 x11_request_forwarding_with_spoofing(0, proto, data);
 936
 937                 /* Read response from the server. */
 938                 type = packet_read();
 939                 if (type == SSH_SMSG_SUCCESS) {
 940                         interactive = 1;
 941                 } else if (type == SSH_SMSG_FAILURE) {
 942                         logit("Warning: Remote host denied X11 forwarding.");
 943                 } else {
 944                         packet_disconnect("Protocol error waiting for X11 forwarding");
 945                 }
 946         }
 947         /* Tell the packet module whether this is an interactive session. */
 948         packet_set_interactive(interactive);
 949
 950         /* Request authentication agent forwarding if appropriate. */
 951         check_agent_present();
 952
 953         if (options.forward_agent) {
 954                 debug("Requesting authentication agent forwarding.");
 955                 auth_request_forwarding();
 956
 957                 /* Read response from the server. */
 958                 type = packet_read();
 959                 packet_check_eom();
 960                 if (type != SSH_SMSG_SUCCESS)
 961                         logit("Warning: Remote host denied authentication agent forwarding.");
 962         }
 963
 964         /* Initiate port forwardings. */
 965         ssh_init_forwarding();
 966
 967         /* If requested, let ssh continue in the background. */
 968         if (fork_after_authentication_flag)
 969                 if (daemon(1, 1) < 0)
 970                         fatal("daemon() failed: %.200s", strerror(errno));
 971
 972         /*
 973          * If a command was specified on the command line, execute the
 974          * command now. Otherwise request the server to start a shell.
 975          */
 976         if (buffer_len(&command) > 0) {
 977                 int len = buffer_len(&command);
 978                 if (len > 900)
 979                         len = 900;
 980                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 981                 packet_start(SSH_CMSG_EXEC_CMD);
 982                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 983                 packet_send();
 984                 packet_write_wait();
 985         } else {
 986                 debug("Requesting shell.");
 987                 packet_start(SSH_CMSG_EXEC_SHELL);
 988                 packet_send();
 989                 packet_write_wait();
 990         }
 991
 992         /* Enter the interactive session. */
 993         return client_loop(have_tty, tty_flag ?
 994             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
 995 }
 996
 997 static void
 998 client_subsystem_reply(int type, u_int32_t seq, void *ctxt)
 999 {
1000         int id, len;
1001
1002         id = packet_get_int();
1003         len = buffer_len(&command);
1004         if (len > 900)
1005                 len = 900;
1006         packet_check_eom();
1007         if (type == SSH2_MSG_CHANNEL_FAILURE)
1008                 fatal("Request for subsystem '%.*s' failed on channel %d",
1009                     len, (u_char *)buffer_ptr(&command), id);
1010 }
1011
1012 void
1013 client_global_request_reply(int type, u_int32_t seq, void *ctxt)
1014 {
1015         int i;
1016
1017         i = client_global_request_id++;
1018         if (i >= options.num_remote_forwards) {
1019                 debug("client_global_request_reply: too many replies %d > %d",
1020                     i, options.num_remote_forwards);
1021                 return;
1022         }
1023         debug("remote forward %s for: listen %d, connect %s:%d",
1024             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1025             options.remote_forwards[i].port,
1026             options.remote_forwards[i].host,
1027             options.remote_forwards[i].host_port);
1028         if (type == SSH2_MSG_REQUEST_FAILURE)
1029                 logit("Warning: remote port forwarding failed for listen port %d",
1030                     options.remote_forwards[i].port);
1031 }
1032
1033 /* request pty/x11/agent/tcpfwd/shell for channel */
1034 static void
1035 ssh_session2_setup(int id, void *arg)
1036 {
1037         int len;
1038         int interactive = 0;
1039         struct termios tio;
1040
1041         debug2("ssh_session2_setup: id %d", id);
1042
1043         if (tty_flag) {
1044                 struct winsize ws;
1045                 char *cp;
1046                 cp = getenv("TERM");
1047                 if (!cp)
1048                         cp = "";
1049                 /* Store window size in the packet. */
1050                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1051                         memset(&ws, 0, sizeof(ws));
1052
1053                 channel_request_start(id, "pty-req", 0);
1054                 packet_put_cstring(cp);
1055                 packet_put_int(ws.ws_col);
1056                 packet_put_int(ws.ws_row);
1057                 packet_put_int(ws.ws_xpixel);
1058                 packet_put_int(ws.ws_ypixel);
1059                 tio = get_saved_tio();
1060                 tty_make_modes(/*ignored*/ 0, &tio);
1061                 packet_send();
1062                 interactive = 1;
1063                 /* XXX wait for reply */
1064         }
1065         if (options.forward_x11 &&
1066             getenv("DISPLAY") != NULL) {
1067                 char *proto, *data;
1068                 /* Get reasonable local authentication information. */
1069                 x11_get_proto(&proto, &data);
1070                 /* Request forwarding with authentication spoofing. */
1071                 debug("Requesting X11 forwarding with authentication spoofing.");
1072                 x11_request_forwarding_with_spoofing(id, proto, data);
1073                 interactive = 1;
1074                 /* XXX wait for reply */
1075         }
1076
1077         check_agent_present();
1078         if (options.forward_agent) {
1079                 debug("Requesting authentication agent forwarding.");
1080                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1081                 packet_send();
1082         }
1083
1084         len = buffer_len(&command);
1085         if (len > 0) {
1086                 if (len > 900)
1087                         len = 900;
1088                 if (subsystem_flag) {
1089                         debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command));
1090                         channel_request_start(id, "subsystem", /*want reply*/ 1);
1091                         /* register callback for reply */
1092                         /* XXX we assume that client_loop has already been called */
1093                         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
1094                         dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1095                 } else {
1096                         debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1097                         channel_request_start(id, "exec", 0);
1098                 }
1099                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1100                 packet_send();
1101         } else {
1102                 channel_request_start(id, "shell", 0);
1103                 packet_send();
1104         }
1105
1106         packet_set_interactive(interactive);
1107 }
1108
1109 /* open new channel for a session */
1110 static int
1111 ssh_session2_open(void)
1112 {
1113         Channel *c;
1114         int window, packetmax, in, out, err;
1115
1116         if (stdin_null_flag) {
1117                 in = open(_PATH_DEVNULL, O_RDONLY);
1118         } else {
1119                 in = dup(STDIN_FILENO);
1120         }
1121         out = dup(STDOUT_FILENO);
1122         err = dup(STDERR_FILENO);
1123
1124         if (in < 0 || out < 0 || err < 0)
1125                 fatal("dup() in/out/err failed");
1126
1127         /* enable nonblocking unless tty */
1128         if (!isatty(in))
1129                 set_nonblock(in);
1130         if (!isatty(out))
1131                 set_nonblock(out);
1132         if (!isatty(err))
1133                 set_nonblock(err);
1134
1135         window = CHAN_SES_WINDOW_DEFAULT;
1136         packetmax = CHAN_SES_PACKET_DEFAULT;
1137         if (tty_flag) {
1138                 window >>= 1;
1139                 packetmax >>= 1;
1140         }
1141         c = channel_new(
1142             "session", SSH_CHANNEL_OPENING, in, out, err,
1143             window, packetmax, CHAN_EXTENDED_WRITE,
1144             "client-session", /*nonblock*/0);
1145
1146         debug3("ssh_session2_open: channel_new: %d", c->self);
1147
1148         channel_send_open(c->self);
1149         if (!no_shell_flag)
1150                 channel_register_confirm(c->self, ssh_session2_setup);
1151
1152         return c->self;
1153 }
1154
1155 static int
1156 ssh_session2(void)
1157 {
1158         int id = -1;
1159
1160         /* XXX should be pre-session */
1161         ssh_init_forwarding();
1162
1163         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1164                 id = ssh_session2_open();
1165
1166         /* If requested, let ssh continue in the background. */
1167         if (fork_after_authentication_flag)
1168                 if (daemon(1, 1) < 0)
1169                         fatal("daemon() failed: %.200s", strerror(errno));
1170
1171         return client_loop(tty_flag, tty_flag ?
1172             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1173 }
1174
1175 static void
1176 load_public_identity_files(void)
1177 {
1178         char *filename;
1179         int i = 0;
1180         Key *public;
1181 #ifdef SMARTCARD
1182         Key **keys;
1183
1184         if (options.smartcard_device != NULL &&
1185             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1186             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1187                 int count = 0;
1188                 for (i = 0; keys[i] != NULL; i++) {
1189                         count++;
1190                         memmove(&options.identity_files[1], &options.identity_files[0],
1191                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1192                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1193                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1194                         options.num_identity_files++;
1195                         options.identity_keys[0] = keys[i];
1196                         options.identity_files[0] = sc_get_key_label(keys[i]);
1197                 }
1198                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1199                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1200                 i = count;
1201                 xfree(keys);
1202         }
1203 #endif /* SMARTCARD */
1204         for (; i < options.num_identity_files; i++) {
1205                 filename = tilde_expand_filename(options.identity_files[i],
1206                     original_real_uid);
1207                 public = key_load_public(filename, NULL);
1208                 debug("identity file %s type %d", filename,
1209                     public ? public->type : -1);
1210                 xfree(options.identity_files[i]);
1211                 options.identity_files[i] = filename;
1212                 options.identity_keys[i] = public;
1213         }
1214 }