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 1.190 2003/02/06 09:27:29 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 IPv4 or IPv6.  This can be set on the command line.
  83    Default value is AF_UNSPEC means both IPv4 and IPv6. */
  84 #ifdef IPV4_DEFAULT
  85 int IPv4or6 = AF_INET;
  86 #else
  87 int IPv4or6 = AF_UNSPEC;
  88 #endif
  89
  90 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
  91 int debug_flag = 0;
  92
  93 /* Flag indicating whether a tty should be allocated */
  94 int tty_flag = 0;
  95 int no_tty_flag = 0;
  96 int force_tty_flag = 0;
  97
  98 /* don't exec a shell */
  99 int no_shell_flag = 0;
 100
 101 /*
 102  * Flag indicating that nothing should be read from stdin.  This can be set
 103  * on the command line.
 104  */
 105 int stdin_null_flag = 0;
 106
 107 /*
 108  * Flag indicating that ssh should fork after authentication.  This is useful
 109  * so that the passphrase can be entered manually, and then ssh goes to the
 110  * background.
 111  */
 112 int fork_after_authentication_flag = 0;
 113
 114 /*
 115  * General data structure for command line options and options configurable
 116  * in configuration files.  See readconf.h.
 117  */
 118 Options options;
 119
 120 /* optional user configfile */
 121 char *config = NULL;
 122
 123 /*
 124  * Name of the host we are connecting to.  This is the name given on the
 125  * command line, or the HostName specified for the user-supplied name in a
 126  * configuration file.
 127  */
 128 char *host;
 129
 130 /* socket address the host resolves to */
 131 struct sockaddr_storage hostaddr;
 132
 133 /* Private host keys. */
 134 Sensitive sensitive_data;
 135
 136 /* Original real UID. */
 137 uid_t original_real_uid;
 138 uid_t original_effective_uid;
 139
 140 /* command to be executed */
 141 Buffer command;
 142
 143 /* Should we execute a command or invoke a subsystem? */
 144 int subsystem_flag = 0;
 145
 146 /* # of replies received for global requests */
 147 static int client_global_request_id = 0;
 148
 149 /* pid of proxycommand child process */
 150 pid_t proxy_command_pid = 0;
 151
 152 /* Prints a help message to the user.  This function never returns. */
 153
 154 static void
 155 usage(void)
 156 {
 157         fprintf(stderr, "Usage: %s [options] host [command]\n", __progname);
 158         fprintf(stderr, "Options:\n");
 159         fprintf(stderr, "  -l user     Log in using this user name.\n");
 160         fprintf(stderr, "  -n          Redirect input from " _PATH_DEVNULL ".\n");
 161         fprintf(stderr, "  -F config   Config file (default: ~/%s).\n",
 162              _PATH_SSH_USER_CONFFILE);
 163         fprintf(stderr, "  -A          Enable authentication agent forwarding.\n");
 164         fprintf(stderr, "  -a          Disable authentication agent forwarding (default).\n");
 165 #ifdef AFS
 166         fprintf(stderr, "  -k          Disable Kerberos ticket and AFS token forwarding.\n");
 167 #endif                          /* AFS */
 168         fprintf(stderr, "  -X          Enable X11 connection forwarding.\n");
 169         fprintf(stderr, "  -x          Disable X11 connection forwarding (default).\n");
 170         fprintf(stderr, "  -i file     Identity for public key authentication "
 171             "(default: ~/.ssh/identity)\n");
 172 #ifdef SMARTCARD
 173         fprintf(stderr, "  -I reader   Set smartcard reader.\n");
 174 #endif
 175         fprintf(stderr, "  -t          Tty; allocate a tty even if command is given.\n");
 176         fprintf(stderr, "  -T          Do not allocate a tty.\n");
 177         fprintf(stderr, "  -v          Verbose; display verbose debugging messages.\n");
 178         fprintf(stderr, "              Multiple -v increases verbosity.\n");
 179         fprintf(stderr, "  -V          Display version number only.\n");
 180         fprintf(stderr, "  -q          Quiet; don't display any warning messages.\n");
 181         fprintf(stderr, "  -f          Fork into background after authentication.\n");
 182         fprintf(stderr, "  -e char     Set escape character; ``none'' = disable (default: ~).\n");
 183
 184         fprintf(stderr, "  -c cipher   Select encryption algorithm\n");
 185         fprintf(stderr, "  -m macs     Specify MAC algorithms for protocol version 2.\n");
 186         fprintf(stderr, "  -p port     Connect to this port.  Server must be on the same port.\n");
 187         fprintf(stderr, "  -L listen-port:host:port   Forward local port to remote address\n");
 188         fprintf(stderr, "  -R listen-port:host:port   Forward remote port to local address\n");
 189         fprintf(stderr, "              These cause %s to listen for connections on a port, and\n", __progname);
 190         fprintf(stderr, "              forward them to the other side by connecting to host:port.\n");
 191         fprintf(stderr, "  -D port     Enable dynamic application-level port forwarding.\n");
 192         fprintf(stderr, "  -C          Enable compression.\n");
 193         fprintf(stderr, "  -N          Do not execute a shell or command.\n");
 194         fprintf(stderr, "  -g          Allow remote hosts to connect to forwarded ports.\n");
 195         fprintf(stderr, "  -1          Force protocol version 1.\n");
 196         fprintf(stderr, "  -2          Force protocol version 2.\n");
 197         fprintf(stderr, "  -4          Use IPv4 only.\n");
 198         fprintf(stderr, "  -6          Use IPv6 only.\n");
 199         fprintf(stderr, "  -o 'option' Process the option as if it was read from a configuration file.\n");
 200         fprintf(stderr, "  -s          Invoke command (mandatory) as SSH2 subsystem.\n");
 201         fprintf(stderr, "  -b addr     Local IP address.\n");
 202         exit(1);
 203 }
 204
 205 static int ssh_session(void);
 206 static int ssh_session2(void);
 207 static void load_public_identity_files(void);
 208
 209 /*
 210  * Main program for the ssh client.
 211  */
 212 int
 213 main(int ac, char **av)
 214 {
 215         int i, opt, exit_status;
 216         u_short fwd_port, fwd_host_port;
 217         char sfwd_port[6], sfwd_host_port[6];
 218         char *p, *cp, buf[256];
 219         struct stat st;
 220         struct passwd *pw;
 221         int dummy;
 222         extern int optind, optreset;
 223         extern char *optarg;
 224
 225         __progname = get_progname(av[0]);
 226         init_rng();
 227
 228         /*
 229          * Save the original real uid.  It will be needed later (uid-swapping
 230          * may clobber the real uid).
 231          */
 232         original_real_uid = getuid();
 233         original_effective_uid = geteuid();
 234
 235         /*
 236          * Use uid-swapping to give up root privileges for the duration of
 237          * option processing.  We will re-instantiate the rights when we are
 238          * ready to create the privileged port, and will permanently drop
 239          * them when the port has been created (actually, when the connection
 240          * has been made, as we may need to create the port several times).
 241          */
 242         PRIV_END;
 243
 244 #ifdef HAVE_SETRLIMIT
 245         /* If we are installed setuid root be careful to not drop core. */
 246         if (original_real_uid != original_effective_uid) {
 247                 struct rlimit rlim;
 248                 rlim.rlim_cur = rlim.rlim_max = 0;
 249                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 250                         fatal("setrlimit failed: %.100s", strerror(errno));
 251         }
 252 #endif
 253         /* Get user data. */
 254         pw = getpwuid(original_real_uid);
 255         if (!pw) {
 256                 log("You don't exist, go away!");
 257                 exit(1);
 258         }
 259         /* Take a copy of the returned structure. */
 260         pw = pwcopy(pw);
 261
 262         /*
 263          * Set our umask to something reasonable, as some files are created
 264          * with the default umask.  This will make them world-readable but
 265          * writable only by the owner, which is ok for all files for which we
 266          * don't set the modes explicitly.
 267          */
 268         umask(022);
 269
 270         /* Initialize option structure to indicate that no values have been set. */
 271         initialize_options(&options);
 272
 273         /* Parse command-line arguments. */
 274         host = NULL;
 275
 276 again:
 277         while ((opt = getopt(ac, av,
 278             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVX")) != -1) {
 279                 switch (opt) {
 280                 case '1':
 281                         options.protocol = SSH_PROTO_1;
 282                         break;
 283                 case '2':
 284                         options.protocol = SSH_PROTO_2;
 285                         break;
 286                 case '4':
 287                         IPv4or6 = AF_INET;
 288                         break;
 289                 case '6':
 290                         IPv4or6 = AF_INET6;
 291                         break;
 292                 case 'n':
 293                         stdin_null_flag = 1;
 294                         break;
 295                 case 'f':
 296                         fork_after_authentication_flag = 1;
 297                         stdin_null_flag = 1;
 298                         break;
 299                 case 'x':
 300                         options.forward_x11 = 0;
 301                         break;
 302                 case 'X':
 303                         options.forward_x11 = 1;
 304                         break;
 305                 case 'g':
 306                         options.gateway_ports = 1;
 307                         break;
 308                 case 'P':       /* deprecated */
 309                         options.use_privileged_port = 0;
 310                         break;
 311                 case 'a':
 312                         options.forward_agent = 0;
 313                         break;
 314                 case 'A':
 315                         options.forward_agent = 1;
 316                         break;
 317 #ifdef AFS
 318                 case 'k':
 319                         options.kerberos_tgt_passing = 0;
 320                         options.afs_token_passing = 0;
 321                         break;
 322 #endif
 323                 case 'i':
 324                         if (stat(optarg, &st) < 0) {
 325                                 fprintf(stderr, "Warning: Identity file %s "
 326                                     "does not exist.\n", optarg);
 327                                 break;
 328                         }
 329                         if (options.num_identity_files >=
 330                             SSH_MAX_IDENTITY_FILES)
 331                                 fatal("Too many identity files specified "
 332                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 333                         options.identity_files[options.num_identity_files++] =
 334                             xstrdup(optarg);
 335                         break;
 336                 case 'I':
 337 #ifdef SMARTCARD
 338                         options.smartcard_device = xstrdup(optarg);
 339 #else
 340                         fprintf(stderr, "no support for smartcards.\n");
 341 #endif
 342                         break;
 343                 case 't':
 344                         if (tty_flag)
 345                                 force_tty_flag = 1;
 346                         tty_flag = 1;
 347                         break;
 348                 case 'v':
 349                         if (0 == debug_flag) {
 350                                 debug_flag = 1;
 351                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 352                         } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
 353                                 options.log_level++;
 354                                 break;
 355                         } else
 356                                 fatal("Too high debugging level.");
 357                         /* fallthrough */
 358                 case 'V':
 359                         fprintf(stderr,
 360                             "%s, SSH protocols %d.%d/%d.%d, OpenSSL 0x%8.8lx\n",
 361                             SSH_VERSION,
 362                             PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
 363                             PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
 364                             SSLeay());
 365                         if (opt == 'V')
 366                                 exit(0);
 367                         break;
 368                 case 'q':
 369                         options.log_level = SYSLOG_LEVEL_QUIET;
 370                         break;
 371                 case 'e':
 372                         if (optarg[0] == '^' && optarg[2] == 0 &&
 373                             (u_char) optarg[1] >= 64 &&
 374                             (u_char) optarg[1] < 128)
 375                                 options.escape_char = (u_char) optarg[1] & 31;
 376                         else if (strlen(optarg) == 1)
 377                                 options.escape_char = (u_char) optarg[0];
 378                         else if (strcmp(optarg, "none") == 0)
 379                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 380                         else {
 381                                 fprintf(stderr, "Bad escape character '%s'.\n",
 382                                     optarg);
 383                                 exit(1);
 384                         }
 385                         break;
 386                 case 'c':
 387                         if (ciphers_valid(optarg)) {
 388                                 /* SSH2 only */
 389                                 options.ciphers = xstrdup(optarg);
 390                                 options.cipher = SSH_CIPHER_ILLEGAL;
 391                         } else {
 392                                 /* SSH1 only */
 393                                 options.cipher = cipher_number(optarg);
 394                                 if (options.cipher == -1) {
 395                                         fprintf(stderr,
 396                                             "Unknown cipher type '%s'\n",
 397                                             optarg);
 398                                         exit(1);
 399                                 }
 400                                 if (options.cipher == SSH_CIPHER_3DES)
 401                                         options.ciphers = "3des-cbc";
 402                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 403                                         options.ciphers = "blowfish-cbc";
 404                                 else
 405                                         options.ciphers = (char *)-1;
 406                         }
 407                         break;
 408                 case 'm':
 409                         if (mac_valid(optarg))
 410                                 options.macs = xstrdup(optarg);
 411                         else {
 412                                 fprintf(stderr, "Unknown mac type '%s'\n",
 413                                     optarg);
 414                                 exit(1);
 415                         }
 416                         break;
 417                 case 'p':
 418                         options.port = a2port(optarg);
 419                         if (options.port == 0) {
 420                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 421                                 exit(1);
 422                         }
 423                         break;
 424                 case 'l':
 425                         options.user = optarg;
 426                         break;
 427
 428                 case 'L':
 429                 case 'R':
 430                         if (sscanf(optarg, "%5[0-9]:%255[^:]:%5[0-9]",
 431                             sfwd_port, buf, sfwd_host_port) != 3 &&
 432                             sscanf(optarg, "%5[0-9]/%255[^/]/%5[0-9]",
 433                             sfwd_port, buf, sfwd_host_port) != 3) {
 434                                 fprintf(stderr,
 435                                     "Bad forwarding specification '%s'\n",
 436                                     optarg);
 437                                 usage();
 438                                 /* NOTREACHED */
 439                         }
 440                         if ((fwd_port = a2port(sfwd_port)) == 0 ||
 441                             (fwd_host_port = a2port(sfwd_host_port)) == 0) {
 442                                 fprintf(stderr,
 443                                     "Bad forwarding port(s) '%s'\n", optarg);
 444                                 exit(1);
 445                         }
 446                         if (opt == 'L')
 447                                 add_local_forward(&options, fwd_port, buf,
 448                                     fwd_host_port);
 449                         else if (opt == 'R')
 450                                 add_remote_forward(&options, fwd_port, buf,
 451                                     fwd_host_port);
 452                         break;
 453
 454                 case 'D':
 455                         fwd_port = a2port(optarg);
 456                         if (fwd_port == 0) {
 457                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 458                                     optarg);
 459                                 exit(1);
 460                         }
 461                         add_local_forward(&options, fwd_port, "socks4", 0);
 462                         break;
 463
 464                 case 'C':
 465                         options.compression = 1;
 466                         break;
 467                 case 'N':
 468                         no_shell_flag = 1;
 469                         no_tty_flag = 1;
 470                         break;
 471                 case 'T':
 472                         no_tty_flag = 1;
 473                         break;
 474                 case 'o':
 475                         dummy = 1;
 476                         if (process_config_line(&options, host ? host : "",
 477                             optarg, "command-line", 0, &dummy) != 0)
 478                                 exit(1);
 479                         break;
 480                 case 's':
 481                         subsystem_flag = 1;
 482                         break;
 483                 case 'b':
 484                         options.bind_address = optarg;
 485                         break;
 486                 case 'F':
 487                         config = optarg;
 488                         break;
 489                 default:
 490                         usage();
 491                 }
 492         }
 493
 494         ac -= optind;
 495         av += optind;
 496
 497         if (ac > 0 && !host && **av != '-') {
 498                 if (strrchr(*av, '@')) {
 499                         p = xstrdup(*av);
 500                         cp = strrchr(p, '@');
 501                         if (cp == NULL || cp == p)
 502                                 usage();
 503                         options.user = p;
 504                         *cp = '\0';
 505                         host = ++cp;
 506                 } else
 507                         host = *av;
 508                 if (ac > 1) {
 509                         optind = optreset = 1;
 510                         goto again;
 511                 }
 512                 ac--, av++;
 513         }
 514
 515         /* Check that we got a host name. */
 516         if (!host)
 517                 usage();
 518
 519         SSLeay_add_all_algorithms();
 520         ERR_load_crypto_strings();
 521         channel_set_af(IPv4or6);
 522
 523         /* Initialize the command to execute on remote host. */
 524         buffer_init(&command);
 525
 526         /*
 527          * Save the command to execute on the remote host in a buffer. There
 528          * is no limit on the length of the command, except by the maximum
 529          * packet size.  Also sets the tty flag if there is no command.
 530          */
 531         if (!ac) {
 532                 /* No command specified - execute shell on a tty. */
 533                 tty_flag = 1;
 534                 if (subsystem_flag) {
 535                         fprintf(stderr,
 536                             "You must specify a subsystem to invoke.\n");
 537                         usage();
 538                 }
 539         } else {
 540                 /* A command has been specified.  Store it into the buffer. */
 541                 for (i = 0; i < ac; i++) {
 542                         if (i)
 543                                 buffer_append(&command, " ", 1);
 544                         buffer_append(&command, av[i], strlen(av[i]));
 545                 }
 546         }
 547
 548         /* Cannot fork to background if no command. */
 549         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 550                 fatal("Cannot fork into background without a command to execute.");
 551
 552         /* Allocate a tty by default if no command specified. */
 553         if (buffer_len(&command) == 0)
 554                 tty_flag = 1;
 555
 556         /* Force no tty */
 557         if (no_tty_flag)
 558                 tty_flag = 0;
 559         /* Do not allocate a tty if stdin is not a tty. */
 560         if (!isatty(fileno(stdin)) && !force_tty_flag) {
 561                 if (tty_flag)
 562                         log("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 563                 tty_flag = 0;
 564         }
 565
 566         /*
 567          * Initialize "log" output.  Since we are the client all output
 568          * actually goes to stderr.
 569          */
 570         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 571             SYSLOG_FACILITY_USER, 1);
 572
 573         /*
 574          * Read per-user configuration file.  Ignore the system wide config
 575          * file if the user specifies a config file on the command line.
 576          */
 577         if (config != NULL) {
 578                 if (!read_config_file(config, host, &options))
 579                         fatal("Can't open user config file %.100s: "
 580                             "%.100s", config, strerror(errno));
 581         } else  {
 582             /*
 583              * Since the config file parsing code aborts if it sees
 584              * options it doesn't recognize, allow users to put
 585              * options specific to compile-time add-ons in alternate
 586              * config files so their primary config file will
 587              * interoperate SSH versions that don't support those
 588              * options.
 589              */
 590 #ifdef GSSAPI
 591                 snprintf(buf, sizeof buf, "%.100s/%.100s.gssapi", pw->pw_dir,
 592                     _PATH_SSH_USER_CONFFILE);
 593                 (void)read_config_file(buf, host, &options);
 594 #ifdef GSI
 595                 snprintf(buf, sizeof buf, "%.100s/%.100s.gsi", pw->pw_dir,
 596                     _PATH_SSH_USER_CONFFILE);
 597                 (void)read_config_file(buf, host, &options);
 598 #endif
 599 #if defined(KRB4) || defined(KRB5)
 600                 snprintf(buf, sizeof buf, "%.100s/%.100s.krb", pw->pw_dir,
 601                     _PATH_SSH_USER_CONFFILE);
 602                 (void)read_config_file(buf, host, &options);
 603 #endif
 604 #ifdef AFS
 605                 snprintf(buf, sizeof buf, "%.100s/%.100s.afs", pw->pw_dir,
 606                     _PATH_SSH_USER_CONFFILE);
 607                 (void)read_config_file(buf, host, &options);
 608 #endif
 609 #endif
 610                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 611                     _PATH_SSH_USER_CONFFILE);
 612                 (void)read_config_file(buf, host, &options);
 613
 614                 /* Read systemwide configuration file after use config. */
 615                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
 616         }
 617
 618         /* Fill configuration defaults. */
 619         fill_default_options(&options);
 620
 621         /* reinit */
 622         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 623
 624         seed_rng();
 625
 626         if (options.user == NULL) {
 627                 options.user = xstrdup(pw->pw_name);
 628                 options.implicit = 1;
 629         }
 630         else options.implicit = 0;
 631
 632         if (options.hostname != NULL)
 633                 host = options.hostname;
 634
 635         if (options.proxy_command != NULL &&
 636             strcmp(options.proxy_command, "none") == 0)
 637                 options.proxy_command = NULL;
 638
 639         /* Disable rhosts authentication if not running as root. */
 640 #ifdef HAVE_CYGWIN
 641         /* Ignore uid if running under Windows */
 642         if (!options.use_privileged_port) {
 643 #else
 644         if (original_effective_uid != 0 || !options.use_privileged_port) {
 645 #endif
 646                 debug("Rhosts Authentication disabled, "
 647                     "originating port will not be trusted.");
 648                 options.rhosts_authentication = 0;
 649         }
 650         /* Open a connection to the remote host. */
 651
 652         if (ssh_connect(host, &hostaddr, options.port, IPv4or6,
 653             options.connection_attempts,
 654 #ifdef HAVE_CYGWIN
 655             options.use_privileged_port,
 656 #else
 657             original_effective_uid == 0 && options.use_privileged_port,
 658 #endif
 659             options.proxy_command) != 0)
 660                 exit(1);
 661
 662         /*
 663          * If we successfully made the connection, load the host private key
 664          * in case we will need it later for combined rsa-rhosts
 665          * authentication. This must be done before releasing extra
 666          * privileges, because the file is only readable by root.
 667          * If we cannot access the private keys, load the public keys
 668          * instead and try to execute the ssh-keysign helper instead.
 669          */
 670         sensitive_data.nkeys = 0;
 671         sensitive_data.keys = NULL;
 672         sensitive_data.external_keysign = 0;
 673         if (options.rhosts_rsa_authentication ||
 674             options.hostbased_authentication) {
 675                 sensitive_data.nkeys = 3;
 676                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 677                     sizeof(Key));
 678
 679                 PRIV_START;
 680                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 681                     _PATH_HOST_KEY_FILE, "", NULL);
 682                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 683                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 684                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 685                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 686                 PRIV_END;
 687
 688                 if (options.hostbased_authentication == 1 &&
 689                     sensitive_data.keys[0] == NULL &&
 690                     sensitive_data.keys[1] == NULL &&
 691                     sensitive_data.keys[2] == NULL) {
 692                         sensitive_data.keys[1] = key_load_public(
 693                             _PATH_HOST_DSA_KEY_FILE, NULL);
 694                         sensitive_data.keys[2] = key_load_public(
 695                             _PATH_HOST_RSA_KEY_FILE, NULL);
 696                         sensitive_data.external_keysign = 1;
 697                 }
 698         }
 699         /*
 700          * Get rid of any extra privileges that we may have.  We will no
 701          * longer need them.  Also, extra privileges could make it very hard
 702          * to read identity files and other non-world-readable files from the
 703          * user's home directory if it happens to be on a NFS volume where
 704          * root is mapped to nobody.
 705          */
 706         seteuid(original_real_uid);
 707         setuid(original_real_uid);
 708
 709         /*
 710          * Now that we are back to our own permissions, create ~/.ssh
 711          * directory if it doesn\'t already exist.
 712          */
 713         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 714         if (stat(buf, &st) < 0)
 715                 if (mkdir(buf, 0700) < 0)
 716                         error("Could not create directory '%.200s'.", buf);
 717
 718         /* load options.identity_files */
 719         load_public_identity_files();
 720
 721         /* Expand ~ in known host file names. */
 722         /* XXX mem-leaks: */
 723         options.system_hostfile =
 724             tilde_expand_filename(options.system_hostfile, original_real_uid);
 725         options.user_hostfile =
 726             tilde_expand_filename(options.user_hostfile, original_real_uid);
 727         options.system_hostfile2 =
 728             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 729         options.user_hostfile2 =
 730             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 731
 732         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 733
 734         /* Log into the remote system.  This never returns if the login fails. */
 735         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 736
 737         /* We no longer need the private host keys.  Clear them now. */
 738         if (sensitive_data.nkeys != 0) {
 739                 for (i = 0; i < sensitive_data.nkeys; i++) {
 740                         if (sensitive_data.keys[i] != NULL) {
 741                                 /* Destroys contents safely */
 742                                 debug3("clear hostkey %d", i);
 743                                 key_free(sensitive_data.keys[i]);
 744                                 sensitive_data.keys[i] = NULL;
 745                         }
 746                 }
 747                 xfree(sensitive_data.keys);
 748         }
 749         for (i = 0; i < options.num_identity_files; i++) {
 750                 if (options.identity_files[i]) {
 751                         xfree(options.identity_files[i]);
 752                         options.identity_files[i] = NULL;
 753                 }
 754                 if (options.identity_keys[i]) {
 755                         key_free(options.identity_keys[i]);
 756                         options.identity_keys[i] = NULL;
 757                 }
 758         }
 759
 760         exit_status = compat20 ? ssh_session2() : ssh_session();
 761         packet_close();
 762
 763         /*
 764          * Send SIGHUP to proxy command if used. We don't wait() in
 765          * case it hangs and instead rely on init to reap the child
 766          */
 767         if (proxy_command_pid > 1)
 768                 kill(proxy_command_pid, SIGHUP);
 769
 770         return exit_status;
 771 }
 772
 773 static void
 774 x11_get_proto(char **_proto, char **_data)
 775 {
 776         char line[512];
 777         static char proto[512], data[512];
 778         FILE *f;
 779         int got_data = 0, i;
 780         char *display;
 781         struct stat st;
 782
 783         *_proto = proto;
 784         *_data = data;
 785         proto[0] = data[0] = '\0';
 786         if (!options.xauth_location ||
 787             (stat(options.xauth_location, &st) == -1)) {
 788                 debug("No xauth program.");
 789         } else {
 790                 if ((display = getenv("DISPLAY")) == NULL) {
 791                         debug("x11_get_proto: DISPLAY not set");
 792                         return;
 793                 }
 794                 /* Try to get Xauthority information for the display. */
 795                 if (strncmp(display, "localhost:", 10) == 0)
 796                         /*
 797                          * Handle FamilyLocal case where $DISPLAY does
 798                          * not match an authorization entry.  For this we
 799                          * just try "xauth list unix:displaynum.screennum".
 800                          * XXX: "localhost" match to determine FamilyLocal
 801                          *      is not perfect.
 802                          */
 803                         snprintf(line, sizeof line, "%s list unix:%s 2>"
 804                             _PATH_DEVNULL, options.xauth_location, display+10);
 805                 else
 806                         snprintf(line, sizeof line, "%s list %.200s 2>"
 807                             _PATH_DEVNULL, options.xauth_location, display);
 808                 debug2("x11_get_proto: %s", line);
 809                 f = popen(line, "r");
 810                 if (f && fgets(line, sizeof(line), f) &&
 811                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 812                         got_data = 1;
 813                 if (f)
 814                         pclose(f);
 815         }
 816         /*
 817          * If we didn't get authentication data, just make up some
 818          * data.  The forwarding code will check the validity of the
 819          * response anyway, and substitute this data.  The X11
 820          * server, however, will ignore this fake data and use
 821          * whatever authentication mechanisms it was using otherwise
 822          * for the local connection.
 823          */
 824         if (!got_data) {
 825                 u_int32_t rand = 0;
 826
 827                 log("Warning: No xauth data; using fake authentication data for X11 forwarding.");
 828                 strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
 829                 for (i = 0; i < 16; i++) {
 830                         if (i % 4 == 0)
 831                                 rand = arc4random();
 832                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
 833                         rand >>= 8;
 834                 }
 835         }
 836 }
 837
 838 static void
 839 ssh_init_forwarding(void)
 840 {
 841         int success = 0;
 842         int i;
 843
 844         /* Initiate local TCP/IP port forwardings. */
 845         for (i = 0; i < options.num_local_forwards; i++) {
 846                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
 847                     options.local_forwards[i].port,
 848                     options.local_forwards[i].host,
 849                     options.local_forwards[i].host_port);
 850                 success += channel_setup_local_fwd_listener(
 851                     options.local_forwards[i].port,
 852                     options.local_forwards[i].host,
 853                     options.local_forwards[i].host_port,
 854                     options.gateway_ports);
 855         }
 856         if (i > 0 && success == 0)
 857                 error("Could not request local forwarding.");
 858
 859         /* Initiate remote TCP/IP port forwardings. */
 860         for (i = 0; i < options.num_remote_forwards; i++) {
 861                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
 862                     options.remote_forwards[i].port,
 863                     options.remote_forwards[i].host,
 864                     options.remote_forwards[i].host_port);
 865                 channel_request_remote_forwarding(
 866                     options.remote_forwards[i].port,
 867                     options.remote_forwards[i].host,
 868                     options.remote_forwards[i].host_port);
 869         }
 870 }
 871
 872 static void
 873 check_agent_present(void)
 874 {
 875         if (options.forward_agent) {
 876                 /* Clear agent forwarding if we don\'t have an agent. */
 877                 if (!ssh_agent_present())
 878                         options.forward_agent = 0;
 879         }
 880 }
 881
 882 static int
 883 ssh_session(void)
 884 {
 885         int type;
 886         int interactive = 0;
 887         int have_tty = 0;
 888         struct winsize ws;
 889         char *cp;
 890
 891         /* Enable compression if requested. */
 892         if (options.compression) {
 893                 debug("Requesting compression at level %d.", options.compression_level);
 894
 895                 if (options.compression_level < 1 || options.compression_level > 9)
 896                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 897
 898                 /* Send the request. */
 899                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 900                 packet_put_int(options.compression_level);
 901                 packet_send();
 902                 packet_write_wait();
 903                 type = packet_read();
 904                 if (type == SSH_SMSG_SUCCESS)
 905                         packet_start_compression(options.compression_level);
 906                 else if (type == SSH_SMSG_FAILURE)
 907                         log("Warning: Remote host refused compression.");
 908                 else
 909                         packet_disconnect("Protocol error waiting for compression response.");
 910         }
 911         /* Allocate a pseudo tty if appropriate. */
 912         if (tty_flag) {
 913                 debug("Requesting pty.");
 914
 915                 /* Start the packet. */
 916                 packet_start(SSH_CMSG_REQUEST_PTY);
 917
 918                 /* Store TERM in the packet.  There is no limit on the
 919                    length of the string. */
 920                 cp = getenv("TERM");
 921                 if (!cp)
 922                         cp = "";
 923                 packet_put_cstring(cp);
 924
 925                 /* Store window size in the packet. */
 926                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 927                         memset(&ws, 0, sizeof(ws));
 928                 packet_put_int(ws.ws_row);
 929                 packet_put_int(ws.ws_col);
 930                 packet_put_int(ws.ws_xpixel);
 931                 packet_put_int(ws.ws_ypixel);
 932
 933                 /* Store tty modes in the packet. */
 934                 tty_make_modes(fileno(stdin), NULL);
 935
 936                 /* Send the packet, and wait for it to leave. */
 937                 packet_send();
 938                 packet_write_wait();
 939
 940                 /* Read response from the server. */
 941                 type = packet_read();
 942                 if (type == SSH_SMSG_SUCCESS) {
 943                         interactive = 1;
 944                         have_tty = 1;
 945                 } else if (type == SSH_SMSG_FAILURE)
 946                         log("Warning: Remote host failed or refused to allocate a pseudo tty.");
 947                 else
 948                         packet_disconnect("Protocol error waiting for pty request response.");
 949         }
 950         /* Request X11 forwarding if enabled and DISPLAY is set. */
 951         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 952                 char *proto, *data;
 953                 /* Get reasonable local authentication information. */
 954                 x11_get_proto(&proto, &data);
 955                 /* Request forwarding with authentication spoofing. */
 956                 debug("Requesting X11 forwarding with authentication spoofing.");
 957                 x11_request_forwarding_with_spoofing(0, proto, data);
 958
 959                 /* Read response from the server. */
 960                 type = packet_read();
 961                 if (type == SSH_SMSG_SUCCESS) {
 962                         interactive = 1;
 963                 } else if (type == SSH_SMSG_FAILURE) {
 964                         log("Warning: Remote host denied X11 forwarding.");
 965                 } else {
 966                         packet_disconnect("Protocol error waiting for X11 forwarding");
 967                 }
 968         }
 969         /* Tell the packet module whether this is an interactive session. */
 970         packet_set_interactive(interactive);
 971
 972         /* Request authentication agent forwarding if appropriate. */
 973         check_agent_present();
 974
 975         if (options.forward_agent) {
 976                 debug("Requesting authentication agent forwarding.");
 977                 auth_request_forwarding();
 978
 979                 /* Read response from the server. */
 980                 type = packet_read();
 981                 packet_check_eom();
 982                 if (type != SSH_SMSG_SUCCESS)
 983                         log("Warning: Remote host denied authentication agent forwarding.");
 984         }
 985
 986         /* Initiate port forwardings. */
 987         ssh_init_forwarding();
 988
 989         /* If requested, let ssh continue in the background. */
 990         if (fork_after_authentication_flag)
 991                 if (daemon(1, 1) < 0)
 992                         fatal("daemon() failed: %.200s", strerror(errno));
 993
 994         /*
 995          * If a command was specified on the command line, execute the
 996          * command now. Otherwise request the server to start a shell.
 997          */
 998         if (buffer_len(&command) > 0) {
 999                 int len = buffer_len(&command);
1000                 if (len > 900)
1001                         len = 900;
1002                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1003                 packet_start(SSH_CMSG_EXEC_CMD);
1004                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1005                 packet_send();
1006                 packet_write_wait();
1007         } else {
1008                 debug("Requesting shell.");
1009                 packet_start(SSH_CMSG_EXEC_SHELL);
1010                 packet_send();
1011                 packet_write_wait();
1012         }
1013
1014         /* Enter the interactive session. */
1015         return client_loop(have_tty, tty_flag ?
1016             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1017 }
1018
1019 static void
1020 client_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1021 {
1022         int id, len;
1023
1024         id = packet_get_int();
1025         len = buffer_len(&command);
1026         if (len > 900)
1027                 len = 900;
1028         packet_check_eom();
1029         if (type == SSH2_MSG_CHANNEL_FAILURE)
1030                 fatal("Request for subsystem '%.*s' failed on channel %d",
1031                     len, (u_char *)buffer_ptr(&command), id);
1032 }
1033
1034 void
1035 client_global_request_reply(int type, u_int32_t seq, void *ctxt)
1036 {
1037         int i;
1038
1039         i = client_global_request_id++;
1040         if (i >= options.num_remote_forwards) {
1041                 debug("client_global_request_reply: too many replies %d > %d",
1042                     i, options.num_remote_forwards);
1043                 return;
1044         }
1045         debug("remote forward %s for: listen %d, connect %s:%d",
1046             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1047             options.remote_forwards[i].port,
1048             options.remote_forwards[i].host,
1049             options.remote_forwards[i].host_port);
1050         if (type == SSH2_MSG_REQUEST_FAILURE)
1051                 log("Warning: remote port forwarding failed for listen port %d",
1052                     options.remote_forwards[i].port);
1053 }
1054
1055 /* request pty/x11/agent/tcpfwd/shell for channel */
1056 static void
1057 ssh_session2_setup(int id, void *arg)
1058 {
1059         int len;
1060         int interactive = 0;
1061         struct termios tio;
1062
1063         debug2("ssh_session2_setup: id %d", id);
1064
1065         if (tty_flag) {
1066                 struct winsize ws;
1067                 char *cp;
1068                 cp = getenv("TERM");
1069                 if (!cp)
1070                         cp = "";
1071                 /* Store window size in the packet. */
1072                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1073                         memset(&ws, 0, sizeof(ws));
1074
1075                 channel_request_start(id, "pty-req", 0);
1076                 packet_put_cstring(cp);
1077                 packet_put_int(ws.ws_col);
1078                 packet_put_int(ws.ws_row);
1079                 packet_put_int(ws.ws_xpixel);
1080                 packet_put_int(ws.ws_ypixel);
1081                 tio = get_saved_tio();
1082                 tty_make_modes(/*ignored*/ 0, &tio);
1083                 packet_send();
1084                 interactive = 1;
1085                 /* XXX wait for reply */
1086         }
1087         if (options.forward_x11 &&
1088             getenv("DISPLAY") != NULL) {
1089                 char *proto, *data;
1090                 /* Get reasonable local authentication information. */
1091                 x11_get_proto(&proto, &data);
1092                 /* Request forwarding with authentication spoofing. */
1093                 debug("Requesting X11 forwarding with authentication spoofing.");
1094                 x11_request_forwarding_with_spoofing(id, proto, data);
1095                 interactive = 1;
1096                 /* XXX wait for reply */
1097         }
1098
1099         check_agent_present();
1100         if (options.forward_agent) {
1101                 debug("Requesting authentication agent forwarding.");
1102                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1103                 packet_send();
1104         }
1105
1106         len = buffer_len(&command);
1107         if (len > 0) {
1108                 if (len > 900)
1109                         len = 900;
1110                 if (subsystem_flag) {
1111                         debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command));
1112                         channel_request_start(id, "subsystem", /*want reply*/ 1);
1113                         /* register callback for reply */
1114                         /* XXX we assume that client_loop has already been called */
1115                         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
1116                         dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1117                 } else {
1118                         debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1119                         channel_request_start(id, "exec", 0);
1120                 }
1121                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1122                 packet_send();
1123         } else {
1124                 channel_request_start(id, "shell", 0);
1125                 packet_send();
1126         }
1127
1128         packet_set_interactive(interactive);
1129 }
1130
1131 /* open new channel for a session */
1132 static int
1133 ssh_session2_open(void)
1134 {
1135         Channel *c;
1136         int window, packetmax, in, out, err;
1137
1138         if (stdin_null_flag) {
1139                 in = open(_PATH_DEVNULL, O_RDONLY);
1140         } else {
1141                 in = dup(STDIN_FILENO);
1142         }
1143         out = dup(STDOUT_FILENO);
1144         err = dup(STDERR_FILENO);
1145
1146         if (in < 0 || out < 0 || err < 0)
1147                 fatal("dup() in/out/err failed");
1148
1149         /* enable nonblocking unless tty */
1150         if (!isatty(in))
1151                 set_nonblock(in);
1152         if (!isatty(out))
1153                 set_nonblock(out);
1154         if (!isatty(err))
1155                 set_nonblock(err);
1156
1157         window = CHAN_SES_WINDOW_DEFAULT;
1158         packetmax = CHAN_SES_PACKET_DEFAULT;
1159         if (tty_flag) {
1160                 window >>= 1;
1161                 packetmax >>= 1;
1162         }
1163         c = channel_new(
1164             "session", SSH_CHANNEL_OPENING, in, out, err,
1165             window, packetmax, CHAN_EXTENDED_WRITE,
1166             xstrdup("client-session"), /*nonblock*/0);
1167
1168         debug3("ssh_session2_open: channel_new: %d", c->self);
1169
1170         channel_send_open(c->self);
1171         if (!no_shell_flag)
1172                 channel_register_confirm(c->self, ssh_session2_setup);
1173
1174         return c->self;
1175 }
1176
1177 static int
1178 ssh_session2(void)
1179 {
1180         int id = -1;
1181
1182         /* XXX should be pre-session */
1183         ssh_init_forwarding();
1184
1185         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1186                 id = ssh_session2_open();
1187
1188         /* If requested, let ssh continue in the background. */
1189         if (fork_after_authentication_flag)
1190                 if (daemon(1, 1) < 0)
1191                         fatal("daemon() failed: %.200s", strerror(errno));
1192
1193         return client_loop(tty_flag, tty_flag ?
1194             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1195 }
1196
1197 static void
1198 load_public_identity_files(void)
1199 {
1200         char *filename;
1201         int i = 0;
1202         Key *public;
1203 #ifdef SMARTCARD
1204         Key **keys;
1205
1206         if (options.smartcard_device != NULL &&
1207             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1208             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1209                 int count = 0;
1210                 for (i = 0; keys[i] != NULL; i++) {
1211                         count++;
1212                         memmove(&options.identity_files[1], &options.identity_files[0],
1213                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1214                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1215                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1216                         options.num_identity_files++;
1217                         options.identity_keys[0] = keys[i];
1218                         options.identity_files[0] = xstrdup("smartcard key");;
1219                 }
1220                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1221                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1222                 i = count;
1223                 xfree(keys);
1224         }
1225 #endif /* SMARTCARD */
1226         for (; i < options.num_identity_files; i++) {
1227                 filename = tilde_expand_filename(options.identity_files[i],
1228                     original_real_uid);
1229                 public = key_load_public(filename, NULL);
1230                 debug("identity file %s type %d", filename,
1231                     public ? public->type : -1);
1232                 xfree(options.identity_files[i]);
1233                 options.identity_files[i] = filename;
1234                 options.identity_keys[i] = public;
1235         }
1236 }