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, 2003 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 1.203 2003/11/21 11:57:03 djm 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, "  -Y          Enable trusted X11 connection forwarding.\n");
 159         fprintf(stderr, "  -x          Disable X11 connection forwarding (default).\n");
 160         fprintf(stderr, "  -i file     Identity for public key authentication "
 161             "(default: ~/.ssh/identity)\n");
 162 #ifdef SMARTCARD
 163         fprintf(stderr, "  -I reader   Set smartcard reader.\n");
 164 #endif
 165         fprintf(stderr, "  -t          Tty; allocate a tty even if command is given.\n");
 166         fprintf(stderr, "  -T          Do not allocate a tty.\n");
 167         fprintf(stderr, "  -v          Verbose; display verbose debugging messages.\n");
 168         fprintf(stderr, "              Multiple -v increases verbosity.\n");
 169         fprintf(stderr, "  -V          Display version number only.\n");
 170         fprintf(stderr, "  -q          Quiet; don't display any warning messages.\n");
 171         fprintf(stderr, "  -f          Fork into background after authentication.\n");
 172         fprintf(stderr, "  -e char     Set escape character; ``none'' = disable (default: ~).\n");
 173
 174         fprintf(stderr, "  -c cipher   Select encryption algorithm\n");
 175         fprintf(stderr, "  -m macs     Specify MAC algorithms for protocol version 2.\n");
 176         fprintf(stderr, "  -p port     Connect to this port.  Server must be on the same port.\n");
 177         fprintf(stderr, "  -L listen-port:host:port   Forward local port to remote address\n");
 178         fprintf(stderr, "  -R listen-port:host:port   Forward remote port to local address\n");
 179         fprintf(stderr, "              These cause %s to listen for connections on a port, and\n", __progname);
 180         fprintf(stderr, "              forward them to the other side by connecting to host:port.\n");
 181         fprintf(stderr, "  -D port     Enable dynamic application-level port forwarding.\n");
 182         fprintf(stderr, "  -C          Enable compression.\n");
 183         fprintf(stderr, "  -N          Do not execute a shell or command.\n");
 184         fprintf(stderr, "  -g          Allow remote hosts to connect to forwarded ports.\n");
 185         fprintf(stderr, "  -1          Force protocol version 1.\n");
 186         fprintf(stderr, "  -2          Force protocol version 2.\n");
 187         fprintf(stderr, "  -4          Use IPv4 only.\n");
 188         fprintf(stderr, "  -6          Use IPv6 only.\n");
 189         fprintf(stderr, "  -o 'option' Process the option as if it was read from a configuration file.\n");
 190         fprintf(stderr, "  -s          Invoke command (mandatory) as SSH2 subsystem.\n");
 191         fprintf(stderr, "  -b addr     Local IP address.\n");
 192         exit(1);
 193 }
 194
 195 static int ssh_session(void);
 196 static int ssh_session2(void);
 197 static void load_public_identity_files(void);
 198
 199 /*
 200  * Main program for the ssh client.
 201  */
 202 int
 203 main(int ac, char **av)
 204 {
 205         int i, opt, exit_status;
 206         u_short fwd_port, fwd_host_port;
 207         char sfwd_port[6], sfwd_host_port[6];
 208         char *p, *cp, buf[256];
 209         struct stat st;
 210         struct passwd *pw;
 211         int dummy;
 212         extern int optind, optreset;
 213         extern char *optarg;
 214
 215         __progname = ssh_get_progname(av[0]);
 216         init_rng();
 217
 218         /*
 219          * Save the original real uid.  It will be needed later (uid-swapping
 220          * may clobber the real uid).
 221          */
 222         original_real_uid = getuid();
 223         original_effective_uid = geteuid();
 224
 225         /*
 226          * Use uid-swapping to give up root privileges for the duration of
 227          * option processing.  We will re-instantiate the rights when we are
 228          * ready to create the privileged port, and will permanently drop
 229          * them when the port has been created (actually, when the connection
 230          * has been made, as we may need to create the port several times).
 231          */
 232         PRIV_END;
 233
 234 #ifdef HAVE_SETRLIMIT
 235         /* If we are installed setuid root be careful to not drop core. */
 236         if (original_real_uid != original_effective_uid) {
 237                 struct rlimit rlim;
 238                 rlim.rlim_cur = rlim.rlim_max = 0;
 239                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 240                         fatal("setrlimit failed: %.100s", strerror(errno));
 241         }
 242 #endif
 243         /* Get user data. */
 244         pw = getpwuid(original_real_uid);
 245         if (!pw) {
 246                 logit("You don't exist, go away!");
 247                 exit(1);
 248         }
 249         /* Take a copy of the returned structure. */
 250         pw = pwcopy(pw);
 251
 252         /*
 253          * Set our umask to something reasonable, as some files are created
 254          * with the default umask.  This will make them world-readable but
 255          * writable only by the owner, which is ok for all files for which we
 256          * don't set the modes explicitly.
 257          */
 258         umask(022);
 259
 260         /* Initialize option structure to indicate that no values have been set. */
 261         initialize_options(&options);
 262
 263         /* Parse command-line arguments. */
 264         host = NULL;
 265
 266 again:
 267         while ((opt = getopt(ac, av,
 268             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVXY")) != -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 'Y':
 296                         options.forward_x11 = 1;
 297                         options.forward_x11_trusted = 1;
 298                         break;
 299                 case 'g':
 300                         options.gateway_ports = 1;
 301                         break;
 302                 case 'P':       /* deprecated */
 303                         options.use_privileged_port = 0;
 304                         break;
 305                 case 'a':
 306                         options.forward_agent = 0;
 307                         break;
 308                 case 'A':
 309                         options.forward_agent = 1;
 310                         break;
 311                 case 'k':
 312                         /* ignored for backward compatibility */
 313                         break;
 314                 case 'i':
 315                         if (stat(optarg, &st) < 0) {
 316                                 fprintf(stderr, "Warning: Identity file %s "
 317                                     "does not exist.\n", optarg);
 318                                 break;
 319                         }
 320                         if (options.num_identity_files >=
 321                             SSH_MAX_IDENTITY_FILES)
 322                                 fatal("Too many identity files specified "
 323                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 324                         options.identity_files[options.num_identity_files++] =
 325                             xstrdup(optarg);
 326                         break;
 327                 case 'I':
 328 #ifdef SMARTCARD
 329                         options.smartcard_device = xstrdup(optarg);
 330 #else
 331                         fprintf(stderr, "no support for smartcards.\n");
 332 #endif
 333                         break;
 334                 case 't':
 335                         if (tty_flag)
 336                                 force_tty_flag = 1;
 337                         tty_flag = 1;
 338                         break;
 339                 case 'v':
 340                         if (debug_flag == 0) {
 341                                 debug_flag = 1;
 342                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 343                         } else {
 344                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 345                                         options.log_level++;
 346                                 break;
 347                         }
 348                         /* fallthrough */
 349                 case 'V':
 350                         fprintf(stderr,
 351                             "%s, SSH protocols %d.%d/%d.%d, %s\n",
 352                             SSH_VERSION,
 353                             PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
 354                             PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
 355                             SSLeay_version(SSLEAY_VERSION));
 356                         if (opt == 'V')
 357                                 exit(0);
 358                         break;
 359                 case 'q':
 360                         options.log_level = SYSLOG_LEVEL_QUIET;
 361                         break;
 362                 case 'e':
 363                         if (optarg[0] == '^' && optarg[2] == 0 &&
 364                             (u_char) optarg[1] >= 64 &&
 365                             (u_char) optarg[1] < 128)
 366                                 options.escape_char = (u_char) optarg[1] & 31;
 367                         else if (strlen(optarg) == 1)
 368                                 options.escape_char = (u_char) optarg[0];
 369                         else if (strcmp(optarg, "none") == 0)
 370                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 371                         else {
 372                                 fprintf(stderr, "Bad escape character '%s'.\n",
 373                                     optarg);
 374                                 exit(1);
 375                         }
 376                         break;
 377                 case 'c':
 378                         if (ciphers_valid(optarg)) {
 379                                 /* SSH2 only */
 380                                 options.ciphers = xstrdup(optarg);
 381                                 options.cipher = SSH_CIPHER_ILLEGAL;
 382                         } else {
 383                                 /* SSH1 only */
 384                                 options.cipher = cipher_number(optarg);
 385                                 if (options.cipher == -1) {
 386                                         fprintf(stderr,
 387                                             "Unknown cipher type '%s'\n",
 388                                             optarg);
 389                                         exit(1);
 390                                 }
 391                                 if (options.cipher == SSH_CIPHER_3DES)
 392                                         options.ciphers = "3des-cbc";
 393                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 394                                         options.ciphers = "blowfish-cbc";
 395                                 else
 396                                         options.ciphers = (char *)-1;
 397                         }
 398                         break;
 399                 case 'm':
 400                         if (mac_valid(optarg))
 401                                 options.macs = xstrdup(optarg);
 402                         else {
 403                                 fprintf(stderr, "Unknown mac type '%s'\n",
 404                                     optarg);
 405                                 exit(1);
 406                         }
 407                         break;
 408                 case 'p':
 409                         options.port = a2port(optarg);
 410                         if (options.port == 0) {
 411                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 412                                 exit(1);
 413                         }
 414                         break;
 415                 case 'l':
 416                         options.user = optarg;
 417                         break;
 418
 419                 case 'L':
 420                 case 'R':
 421                         if (sscanf(optarg, "%5[0123456789]:%255[^:]:%5[0123456789]",
 422                             sfwd_port, buf, sfwd_host_port) != 3 &&
 423                             sscanf(optarg, "%5[0123456789]/%255[^/]/%5[0123456789]",
 424                             sfwd_port, buf, sfwd_host_port) != 3) {
 425                                 fprintf(stderr,
 426                                     "Bad forwarding specification '%s'\n",
 427                                     optarg);
 428                                 usage();
 429                                 /* NOTREACHED */
 430                         }
 431                         if ((fwd_port = a2port(sfwd_port)) == 0 ||
 432                             (fwd_host_port = a2port(sfwd_host_port)) == 0) {
 433                                 fprintf(stderr,
 434                                     "Bad forwarding port(s) '%s'\n", optarg);
 435                                 exit(1);
 436                         }
 437                         if (opt == 'L')
 438                                 add_local_forward(&options, fwd_port, buf,
 439                                     fwd_host_port);
 440                         else if (opt == 'R')
 441                                 add_remote_forward(&options, fwd_port, buf,
 442                                     fwd_host_port);
 443                         break;
 444
 445                 case 'D':
 446                         fwd_port = a2port(optarg);
 447                         if (fwd_port == 0) {
 448                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 449                                     optarg);
 450                                 exit(1);
 451                         }
 452                         add_local_forward(&options, fwd_port, "socks", 0);
 453                         break;
 454
 455                 case 'C':
 456                         options.compression = 1;
 457                         break;
 458                 case 'N':
 459                         no_shell_flag = 1;
 460                         no_tty_flag = 1;
 461                         break;
 462                 case 'T':
 463                         no_tty_flag = 1;
 464                         break;
 465                 case 'o':
 466                         dummy = 1;
 467                         if (process_config_line(&options, host ? host : "",
 468                             optarg, "command-line", 0, &dummy) != 0)
 469                                 exit(1);
 470                         break;
 471                 case 's':
 472                         subsystem_flag = 1;
 473                         break;
 474                 case 'b':
 475                         options.bind_address = optarg;
 476                         break;
 477                 case 'F':
 478                         config = optarg;
 479                         break;
 480                 default:
 481                         usage();
 482                 }
 483         }
 484
 485         ac -= optind;
 486         av += optind;
 487
 488         if (ac > 0 && !host && **av != '-') {
 489                 if (strrchr(*av, '@')) {
 490                         p = xstrdup(*av);
 491                         cp = strrchr(p, '@');
 492                         if (cp == NULL || cp == p)
 493                                 usage();
 494                         options.user = p;
 495                         *cp = '\0';
 496                         host = ++cp;
 497                 } else
 498                         host = *av;
 499                 if (ac > 1) {
 500                         optind = optreset = 1;
 501                         goto again;
 502                 }
 503                 ac--, av++;
 504         }
 505
 506         /* Check that we got a host name. */
 507         if (!host)
 508                 usage();
 509
 510         SSLeay_add_all_algorithms();
 511         ERR_load_crypto_strings();
 512
 513         /* Initialize the command to execute on remote host. */
 514         buffer_init(&command);
 515
 516         /*
 517          * Save the command to execute on the remote host in a buffer. There
 518          * is no limit on the length of the command, except by the maximum
 519          * packet size.  Also sets the tty flag if there is no command.
 520          */
 521         if (!ac) {
 522                 /* No command specified - execute shell on a tty. */
 523                 tty_flag = 1;
 524                 if (subsystem_flag) {
 525                         fprintf(stderr,
 526                             "You must specify a subsystem to invoke.\n");
 527                         usage();
 528                 }
 529         } else {
 530                 /* A command has been specified.  Store it into the buffer. */
 531                 for (i = 0; i < ac; i++) {
 532                         if (i)
 533                                 buffer_append(&command, " ", 1);
 534                         buffer_append(&command, av[i], strlen(av[i]));
 535                 }
 536         }
 537
 538         /* Cannot fork to background if no command. */
 539         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 540                 fatal("Cannot fork into background without a command to execute.");
 541
 542         /* Allocate a tty by default if no command specified. */
 543         if (buffer_len(&command) == 0)
 544                 tty_flag = 1;
 545
 546         /* Force no tty */
 547         if (no_tty_flag)
 548                 tty_flag = 0;
 549         /* Do not allocate a tty if stdin is not a tty. */
 550         if (!isatty(fileno(stdin)) && !force_tty_flag) {
 551                 if (tty_flag)
 552                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 553                 tty_flag = 0;
 554         }
 555
 556         /*
 557          * Initialize "log" output.  Since we are the client all output
 558          * actually goes to stderr.
 559          */
 560         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 561             SYSLOG_FACILITY_USER, 1);
 562
 563         /*
 564          * Read per-user configuration file.  Ignore the system wide config
 565          * file if the user specifies a config file on the command line.
 566          */
 567         if (config != NULL) {
 568                 if (!read_config_file(config, host, &options))
 569                         fatal("Can't open user config file %.100s: "
 570                             "%.100s", config, strerror(errno));
 571         } else  {
 572                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 573                     _PATH_SSH_USER_CONFFILE);
 574                 (void)read_config_file(buf, host, &options);
 575
 576                 /* Read systemwide configuration file after use config. */
 577                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
 578         }
 579
 580         /* Fill configuration defaults. */
 581         fill_default_options(&options);
 582
 583         channel_set_af(options.address_family);
 584
 585         /* reinit */
 586         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 587
 588         seed_rng();
 589
 590         if (options.user == NULL)
 591                 options.user = xstrdup(pw->pw_name);
 592
 593         if (options.hostname != NULL)
 594                 host = options.hostname;
 595
 596         /* force lowercase for hostkey matching */
 597         if (options.host_key_alias != NULL) {
 598                 for (p = options.host_key_alias; *p; p++)
 599                         if (isupper(*p))
 600                                 *p = tolower(*p);
 601         }
 602
 603         if (options.proxy_command != NULL &&
 604             strcmp(options.proxy_command, "none") == 0)
 605                 options.proxy_command = NULL;
 606
 607         /* Open a connection to the remote host. */
 608         if (ssh_connect(host, &hostaddr, options.port,
 609             options.address_family, options.connection_attempts,
 610 #ifdef HAVE_CYGWIN
 611             options.use_privileged_port,
 612 #else
 613             original_effective_uid == 0 && options.use_privileged_port,
 614 #endif
 615             options.proxy_command) != 0)
 616                 exit(1);
 617
 618         /*
 619          * If we successfully made the connection, load the host private key
 620          * in case we will need it later for combined rsa-rhosts
 621          * authentication. This must be done before releasing extra
 622          * privileges, because the file is only readable by root.
 623          * If we cannot access the private keys, load the public keys
 624          * instead and try to execute the ssh-keysign helper instead.
 625          */
 626         sensitive_data.nkeys = 0;
 627         sensitive_data.keys = NULL;
 628         sensitive_data.external_keysign = 0;
 629         if (options.rhosts_rsa_authentication ||
 630             options.hostbased_authentication) {
 631                 sensitive_data.nkeys = 3;
 632                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 633                     sizeof(Key));
 634
 635                 PRIV_START;
 636                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 637                     _PATH_HOST_KEY_FILE, "", NULL);
 638                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 639                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 640                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 641                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 642                 PRIV_END;
 643
 644                 if (options.hostbased_authentication == 1 &&
 645                     sensitive_data.keys[0] == NULL &&
 646                     sensitive_data.keys[1] == NULL &&
 647                     sensitive_data.keys[2] == NULL) {
 648                         sensitive_data.keys[1] = key_load_public(
 649                             _PATH_HOST_DSA_KEY_FILE, NULL);
 650                         sensitive_data.keys[2] = key_load_public(
 651                             _PATH_HOST_RSA_KEY_FILE, NULL);
 652                         sensitive_data.external_keysign = 1;
 653                 }
 654         }
 655         /*
 656          * Get rid of any extra privileges that we may have.  We will no
 657          * longer need them.  Also, extra privileges could make it very hard
 658          * to read identity files and other non-world-readable files from the
 659          * user's home directory if it happens to be on a NFS volume where
 660          * root is mapped to nobody.
 661          */
 662         seteuid(original_real_uid);
 663         setuid(original_real_uid);
 664
 665         /*
 666          * Now that we are back to our own permissions, create ~/.ssh
 667          * directory if it doesn\'t already exist.
 668          */
 669         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 670         if (stat(buf, &st) < 0)
 671                 if (mkdir(buf, 0700) < 0)
 672                         error("Could not create directory '%.200s'.", buf);
 673
 674         /* load options.identity_files */
 675         load_public_identity_files();
 676
 677         /* Expand ~ in known host file names. */
 678         /* XXX mem-leaks: */
 679         options.system_hostfile =
 680             tilde_expand_filename(options.system_hostfile, original_real_uid);
 681         options.user_hostfile =
 682             tilde_expand_filename(options.user_hostfile, original_real_uid);
 683         options.system_hostfile2 =
 684             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 685         options.user_hostfile2 =
 686             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 687
 688         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 689
 690         /* Log into the remote system.  This never returns if the login fails. */
 691         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 692
 693         /* We no longer need the private host keys.  Clear them now. */
 694         if (sensitive_data.nkeys != 0) {
 695                 for (i = 0; i < sensitive_data.nkeys; i++) {
 696                         if (sensitive_data.keys[i] != NULL) {
 697                                 /* Destroys contents safely */
 698                                 debug3("clear hostkey %d", i);
 699                                 key_free(sensitive_data.keys[i]);
 700                                 sensitive_data.keys[i] = NULL;
 701                         }
 702                 }
 703                 xfree(sensitive_data.keys);
 704         }
 705         for (i = 0; i < options.num_identity_files; i++) {
 706                 if (options.identity_files[i]) {
 707                         xfree(options.identity_files[i]);
 708                         options.identity_files[i] = NULL;
 709                 }
 710                 if (options.identity_keys[i]) {
 711                         key_free(options.identity_keys[i]);
 712                         options.identity_keys[i] = NULL;
 713                 }
 714         }
 715
 716         exit_status = compat20 ? ssh_session2() : ssh_session();
 717         packet_close();
 718
 719         /*
 720          * Send SIGHUP to proxy command if used. We don't wait() in
 721          * case it hangs and instead rely on init to reap the child
 722          */
 723         if (proxy_command_pid > 1)
 724                 kill(proxy_command_pid, SIGHUP);
 725
 726         return exit_status;
 727 }
 728
 729 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
 730
 731 static void
 732 x11_get_proto(char **_proto, char **_data)
 733 {
 734         char cmd[1024];
 735         char line[512];
 736         char xdisplay[512];
 737         static char proto[512], data[512];
 738         FILE *f;
 739         int got_data = 0, generated = 0, do_unlink = 0, i;
 740         char *display, *xauthdir, *xauthfile;
 741         struct stat st;
 742
 743         xauthdir = xauthfile = NULL;
 744         *_proto = proto;
 745         *_data = data;
 746         proto[0] = data[0] = '\0';
 747
 748         if (!options.xauth_location ||
 749             (stat(options.xauth_location, &st) == -1)) {
 750                 debug("No xauth program.");
 751         } else {
 752                 if ((display = getenv("DISPLAY")) == NULL) {
 753                         debug("x11_get_proto: DISPLAY not set");
 754                         return;
 755                 }
 756                 /*
 757                  * Handle FamilyLocal case where $DISPLAY does
 758                  * not match an authorization entry.  For this we
 759                  * just try "xauth list unix:displaynum.screennum".
 760                  * XXX: "localhost" match to determine FamilyLocal
 761                  *      is not perfect.
 762                  */
 763                 if (strncmp(display, "localhost:", 10) == 0) {
 764                         snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
 765                             display + 10);
 766                         display = xdisplay;
 767                 }
 768                 if (options.forward_x11_trusted == 0) {
 769                         xauthdir = xmalloc(MAXPATHLEN);
 770                         xauthfile = xmalloc(MAXPATHLEN);
 771                         strlcpy(xauthdir, "/tmp/ssh-XXXXXXXXXX", MAXPATHLEN);
 772                         if (mkdtemp(xauthdir) != NULL) {
 773                                 do_unlink = 1;
 774                                 snprintf(xauthfile, MAXPATHLEN, "%s/xauthfile",
 775                                     xauthdir);
 776                                 snprintf(cmd, sizeof(cmd),
 777                                     "%s -f %s generate %s " SSH_X11_PROTO
 778                                     " untrusted timeout 120 2>" _PATH_DEVNULL,
 779                                     options.xauth_location, xauthfile, display);
 780                                 debug2("x11_get_proto: %s", cmd);
 781                                 if (system(cmd) == 0)
 782                                         generated = 1;
 783                         }
 784                 }
 785                 snprintf(cmd, sizeof(cmd),
 786                     "%s %s%s list %s . 2>" _PATH_DEVNULL,
 787                     options.xauth_location,
 788                     generated ? "-f " : "" ,
 789                     generated ? xauthfile : "",
 790                     display);
 791                 debug2("x11_get_proto: %s", cmd);
 792                 f = popen(cmd, "r");
 793                 if (f && fgets(line, sizeof(line), f) &&
 794                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 795                         got_data = 1;
 796                 if (f)
 797                         pclose(f);
 798         }
 799
 800         if (do_unlink) {
 801                 unlink(xauthfile);
 802                 rmdir(xauthdir);
 803         }
 804         if (xauthdir)
 805                 xfree(xauthdir);
 806         if (xauthfile)
 807                 xfree(xauthfile);
 808
 809         /*
 810          * If we didn't get authentication data, just make up some
 811          * data.  The forwarding code will check the validity of the
 812          * response anyway, and substitute this data.  The X11
 813          * server, however, will ignore this fake data and use
 814          * whatever authentication mechanisms it was using otherwise
 815          * for the local connection.
 816          */
 817         if (!got_data) {
 818                 u_int32_t rand = 0;
 819
 820                 logit("Warning: No xauth data; "
 821                     "using fake authentication data for X11 forwarding.");
 822                 strlcpy(proto, SSH_X11_PROTO, sizeof proto);
 823                 for (i = 0; i < 16; i++) {
 824                         if (i % 4 == 0)
 825                                 rand = arc4random();
 826                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
 827                             rand & 0xff);
 828                         rand >>= 8;
 829                 }
 830         }
 831 }
 832
 833 static void
 834 ssh_init_forwarding(void)
 835 {
 836         int success = 0;
 837         int i;
 838
 839         /* Initiate local TCP/IP port forwardings. */
 840         for (i = 0; i < options.num_local_forwards; i++) {
 841                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
 842                     options.local_forwards[i].port,
 843                     options.local_forwards[i].host,
 844                     options.local_forwards[i].host_port);
 845                 success += channel_setup_local_fwd_listener(
 846                     options.local_forwards[i].port,
 847                     options.local_forwards[i].host,
 848                     options.local_forwards[i].host_port,
 849                     options.gateway_ports);
 850         }
 851         if (i > 0 && success == 0)
 852                 error("Could not request local forwarding.");
 853
 854         /* Initiate remote TCP/IP port forwardings. */
 855         for (i = 0; i < options.num_remote_forwards; i++) {
 856                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
 857                     options.remote_forwards[i].port,
 858                     options.remote_forwards[i].host,
 859                     options.remote_forwards[i].host_port);
 860                 channel_request_remote_forwarding(
 861                     options.remote_forwards[i].port,
 862                     options.remote_forwards[i].host,
 863                     options.remote_forwards[i].host_port);
 864         }
 865 }
 866
 867 static void
 868 check_agent_present(void)
 869 {
 870         if (options.forward_agent) {
 871                 /* Clear agent forwarding if we don\'t have an agent. */
 872                 if (!ssh_agent_present())
 873                         options.forward_agent = 0;
 874         }
 875 }
 876
 877 static int
 878 ssh_session(void)
 879 {
 880         int type;
 881         int interactive = 0;
 882         int have_tty = 0;
 883         struct winsize ws;
 884         char *cp;
 885
 886         /* Enable compression if requested. */
 887         if (options.compression) {
 888                 debug("Requesting compression at level %d.", options.compression_level);
 889
 890                 if (options.compression_level < 1 || options.compression_level > 9)
 891                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 892
 893                 /* Send the request. */
 894                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 895                 packet_put_int(options.compression_level);
 896                 packet_send();
 897                 packet_write_wait();
 898                 type = packet_read();
 899                 if (type == SSH_SMSG_SUCCESS)
 900                         packet_start_compression(options.compression_level);
 901                 else if (type == SSH_SMSG_FAILURE)
 902                         logit("Warning: Remote host refused compression.");
 903                 else
 904                         packet_disconnect("Protocol error waiting for compression response.");
 905         }
 906         /* Allocate a pseudo tty if appropriate. */
 907         if (tty_flag) {
 908                 debug("Requesting pty.");
 909
 910                 /* Start the packet. */
 911                 packet_start(SSH_CMSG_REQUEST_PTY);
 912
 913                 /* Store TERM in the packet.  There is no limit on the
 914                    length of the string. */
 915                 cp = getenv("TERM");
 916                 if (!cp)
 917                         cp = "";
 918                 packet_put_cstring(cp);
 919
 920                 /* Store window size in the packet. */
 921                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 922                         memset(&ws, 0, sizeof(ws));
 923                 packet_put_int(ws.ws_row);
 924                 packet_put_int(ws.ws_col);
 925                 packet_put_int(ws.ws_xpixel);
 926                 packet_put_int(ws.ws_ypixel);
 927
 928                 /* Store tty modes in the packet. */
 929                 tty_make_modes(fileno(stdin), NULL);
 930
 931                 /* Send the packet, and wait for it to leave. */
 932                 packet_send();
 933                 packet_write_wait();
 934
 935                 /* Read response from the server. */
 936                 type = packet_read();
 937                 if (type == SSH_SMSG_SUCCESS) {
 938                         interactive = 1;
 939                         have_tty = 1;
 940                 } else if (type == SSH_SMSG_FAILURE)
 941                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 942                 else
 943                         packet_disconnect("Protocol error waiting for pty request response.");
 944         }
 945         /* Request X11 forwarding if enabled and DISPLAY is set. */
 946         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 947                 char *proto, *data;
 948                 /* Get reasonable local authentication information. */
 949                 x11_get_proto(&proto, &data);
 950                 /* Request forwarding with authentication spoofing. */
 951                 debug("Requesting X11 forwarding with authentication spoofing.");
 952                 x11_request_forwarding_with_spoofing(0, proto, data);
 953
 954                 /* Read response from the server. */
 955                 type = packet_read();
 956                 if (type == SSH_SMSG_SUCCESS) {
 957                         interactive = 1;
 958                 } else if (type == SSH_SMSG_FAILURE) {
 959                         logit("Warning: Remote host denied X11 forwarding.");
 960                 } else {
 961                         packet_disconnect("Protocol error waiting for X11 forwarding");
 962                 }
 963         }
 964         /* Tell the packet module whether this is an interactive session. */
 965         packet_set_interactive(interactive);
 966
 967         /* Request authentication agent forwarding if appropriate. */
 968         check_agent_present();
 969
 970         if (options.forward_agent) {
 971                 debug("Requesting authentication agent forwarding.");
 972                 auth_request_forwarding();
 973
 974                 /* Read response from the server. */
 975                 type = packet_read();
 976                 packet_check_eom();
 977                 if (type != SSH_SMSG_SUCCESS)
 978                         logit("Warning: Remote host denied authentication agent forwarding.");
 979         }
 980
 981         /* Initiate port forwardings. */
 982         ssh_init_forwarding();
 983
 984         /* If requested, let ssh continue in the background. */
 985         if (fork_after_authentication_flag)
 986                 if (daemon(1, 1) < 0)
 987                         fatal("daemon() failed: %.200s", strerror(errno));
 988
 989         /*
 990          * If a command was specified on the command line, execute the
 991          * command now. Otherwise request the server to start a shell.
 992          */
 993         if (buffer_len(&command) > 0) {
 994                 int len = buffer_len(&command);
 995                 if (len > 900)
 996                         len = 900;
 997                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 998                 packet_start(SSH_CMSG_EXEC_CMD);
 999                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1000                 packet_send();
1001                 packet_write_wait();
1002         } else {
1003                 debug("Requesting shell.");
1004                 packet_start(SSH_CMSG_EXEC_SHELL);
1005                 packet_send();
1006                 packet_write_wait();
1007         }
1008
1009         /* Enter the interactive session. */
1010         return client_loop(have_tty, tty_flag ?
1011             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1012 }
1013
1014 static void
1015 client_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1016 {
1017         int id, len;
1018
1019         id = packet_get_int();
1020         len = buffer_len(&command);
1021         if (len > 900)
1022                 len = 900;
1023         packet_check_eom();
1024         if (type == SSH2_MSG_CHANNEL_FAILURE)
1025                 fatal("Request for subsystem '%.*s' failed on channel %d",
1026                     len, (u_char *)buffer_ptr(&command), id);
1027 }
1028
1029 void
1030 client_global_request_reply(int type, u_int32_t seq, void *ctxt)
1031 {
1032         int i;
1033
1034         i = client_global_request_id++;
1035         if (i >= options.num_remote_forwards) {
1036                 debug("client_global_request_reply: too many replies %d > %d",
1037                     i, options.num_remote_forwards);
1038                 return;
1039         }
1040         debug("remote forward %s for: listen %d, connect %s:%d",
1041             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1042             options.remote_forwards[i].port,
1043             options.remote_forwards[i].host,
1044             options.remote_forwards[i].host_port);
1045         if (type == SSH2_MSG_REQUEST_FAILURE)
1046                 logit("Warning: remote port forwarding failed for listen port %d",
1047                     options.remote_forwards[i].port);
1048 }
1049
1050 /* request pty/x11/agent/tcpfwd/shell for channel */
1051 static void
1052 ssh_session2_setup(int id, void *arg)
1053 {
1054         int len;
1055         int interactive = 0;
1056         struct termios tio;
1057
1058         debug2("ssh_session2_setup: id %d", id);
1059
1060         if (tty_flag) {
1061                 struct winsize ws;
1062                 char *cp;
1063                 cp = getenv("TERM");
1064                 if (!cp)
1065                         cp = "";
1066                 /* Store window size in the packet. */
1067                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1068                         memset(&ws, 0, sizeof(ws));
1069
1070                 channel_request_start(id, "pty-req", 0);
1071                 packet_put_cstring(cp);
1072                 packet_put_int(ws.ws_col);
1073                 packet_put_int(ws.ws_row);
1074                 packet_put_int(ws.ws_xpixel);
1075                 packet_put_int(ws.ws_ypixel);
1076                 tio = get_saved_tio();
1077                 tty_make_modes(/*ignored*/ 0, &tio);
1078                 packet_send();
1079                 interactive = 1;
1080                 /* XXX wait for reply */
1081         }
1082         if (options.forward_x11 &&
1083             getenv("DISPLAY") != NULL) {
1084                 char *proto, *data;
1085                 /* Get reasonable local authentication information. */
1086                 x11_get_proto(&proto, &data);
1087                 /* Request forwarding with authentication spoofing. */
1088                 debug("Requesting X11 forwarding with authentication spoofing.");
1089                 x11_request_forwarding_with_spoofing(id, proto, data);
1090                 interactive = 1;
1091                 /* XXX wait for reply */
1092         }
1093
1094         check_agent_present();
1095         if (options.forward_agent) {
1096                 debug("Requesting authentication agent forwarding.");
1097                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1098                 packet_send();
1099         }
1100
1101         len = buffer_len(&command);
1102         if (len > 0) {
1103                 if (len > 900)
1104                         len = 900;
1105                 if (subsystem_flag) {
1106                         debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command));
1107                         channel_request_start(id, "subsystem", /*want reply*/ 1);
1108                         /* register callback for reply */
1109                         /* XXX we assume that client_loop has already been called */
1110                         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
1111                         dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1112                 } else {
1113                         debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1114                         channel_request_start(id, "exec", 0);
1115                 }
1116                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1117                 packet_send();
1118         } else {
1119                 channel_request_start(id, "shell", 0);
1120                 packet_send();
1121         }
1122
1123         packet_set_interactive(interactive);
1124 }
1125
1126 /* open new channel for a session */
1127 static int
1128 ssh_session2_open(void)
1129 {
1130         Channel *c;
1131         int window, packetmax, in, out, err;
1132
1133         if (stdin_null_flag) {
1134                 in = open(_PATH_DEVNULL, O_RDONLY);
1135         } else {
1136                 in = dup(STDIN_FILENO);
1137         }
1138         out = dup(STDOUT_FILENO);
1139         err = dup(STDERR_FILENO);
1140
1141         if (in < 0 || out < 0 || err < 0)
1142                 fatal("dup() in/out/err failed");
1143
1144         /* enable nonblocking unless tty */
1145         if (!isatty(in))
1146                 set_nonblock(in);
1147         if (!isatty(out))
1148                 set_nonblock(out);
1149         if (!isatty(err))
1150                 set_nonblock(err);
1151
1152         window = CHAN_SES_WINDOW_DEFAULT;
1153         packetmax = CHAN_SES_PACKET_DEFAULT;
1154         if (tty_flag) {
1155                 window >>= 1;
1156                 packetmax >>= 1;
1157         }
1158         c = channel_new(
1159             "session", SSH_CHANNEL_OPENING, in, out, err,
1160             window, packetmax, CHAN_EXTENDED_WRITE,
1161             "client-session", /*nonblock*/0);
1162
1163         debug3("ssh_session2_open: channel_new: %d", c->self);
1164
1165         channel_send_open(c->self);
1166         if (!no_shell_flag)
1167                 channel_register_confirm(c->self, ssh_session2_setup);
1168
1169         return c->self;
1170 }
1171
1172 static int
1173 ssh_session2(void)
1174 {
1175         int id = -1;
1176
1177         /* XXX should be pre-session */
1178         ssh_init_forwarding();
1179
1180         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1181                 id = ssh_session2_open();
1182
1183         /* If requested, let ssh continue in the background. */
1184         if (fork_after_authentication_flag)
1185                 if (daemon(1, 1) < 0)
1186                         fatal("daemon() failed: %.200s", strerror(errno));
1187
1188         return client_loop(tty_flag, tty_flag ?
1189             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1190 }
1191
1192 static void
1193 load_public_identity_files(void)
1194 {
1195         char *filename;
1196         int i = 0;
1197         Key *public;
1198 #ifdef SMARTCARD
1199         Key **keys;
1200
1201         if (options.smartcard_device != NULL &&
1202             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1203             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1204                 int count = 0;
1205                 for (i = 0; keys[i] != NULL; i++) {
1206                         count++;
1207                         memmove(&options.identity_files[1], &options.identity_files[0],
1208                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1209                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1210                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1211                         options.num_identity_files++;
1212                         options.identity_keys[0] = keys[i];
1213                         options.identity_files[0] = sc_get_key_label(keys[i]);
1214                 }
1215                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1216                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1217                 i = count;
1218                 xfree(keys);
1219         }
1220 #endif /* SMARTCARD */
1221         for (; i < options.num_identity_files; i++) {
1222                 filename = tilde_expand_filename(options.identity_files[i],
1223                     original_real_uid);
1224                 public = key_load_public(filename, NULL);
1225                 debug("identity file %s type %d", filename,
1226                     public ? public->type : -1);
1227                 xfree(options.identity_files[i]);
1228                 options.identity_files[i] = filename;
1229                 options.identity_keys[i] = public;
1230         }
1231 }