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, 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 1.257 2005/12/20 04:41:07 dtucker 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 "bufaux.h"
  57 #include "channels.h"
  58 #include "key.h"
  59 #include "authfd.h"
  60 #include "authfile.h"
  61 #include "pathnames.h"
  62 #include "dispatch.h"
  63 #include "clientloop.h"
  64 #include "log.h"
  65 #include "readconf.h"
  66 #include "sshconnect.h"
  67 #include "misc.h"
  68 #include "kex.h"
  69 #include "mac.h"
  70 #include "sshpty.h"
  71 #include "match.h"
  72 #include "msg.h"
  73 #include "monitor_fdpass.h"
  74 #include "uidswap.h"
  75
  76 #ifdef SMARTCARD
  77 #include "scard.h"
  78 #endif
  79
  80 extern char *__progname;
  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 /* fd to control socket */
 145 int control_fd = -1;
 146
 147 /* Multiplexing control command */
 148 static u_int mux_command = 0;
 149
 150 /* Only used in control client mode */
 151 volatile sig_atomic_t control_client_terminate = 0;
 152 u_int control_server_pid = 0;
 153
 154 /* Prints a help message to the user.  This function never returns. */
 155
 156 static void
 157 usage(void)
 158 {
 159         fprintf(stderr,
 160 "usage: ssh [-1246AaCfgkMNnqrsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 161 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 162 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 163 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 164 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 165 "           [-w tunnel:tunnel] [user@]hostname [command]\n"
 166 "           [-r Receive Buffer Size in K]\n"
 167         );
 168         exit(255);
 169 }
 170
 171 static int ssh_session(void);
 172 static int ssh_session2(void);
 173 static void load_public_identity_files(void);
 174 static void control_client(const char *path);
 175
 176 /*
 177  * Main program for the ssh client.
 178  */
 179 int
 180 main(int ac, char **av)
 181 {
 182         int i, opt, exit_status;
 183         char *p, *cp, *line, buf[256];
 184         struct stat st;
 185         struct passwd *pw;
 186         int dummy;
 187         extern int optind, optreset;
 188         extern char *optarg;
 189         struct servent *sp;
 190         Forward fwd;
 191
 192         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 193         sanitise_stdfd();
 194
 195         __progname = ssh_get_progname(av[0]);
 196         init_rng();
 197
 198         /*
 199          * Save the original real uid.  It will be needed later (uid-swapping
 200          * may clobber the real uid).
 201          */
 202         original_real_uid = getuid();
 203         original_effective_uid = geteuid();
 204
 205         /*
 206          * Use uid-swapping to give up root privileges for the duration of
 207          * option processing.  We will re-instantiate the rights when we are
 208          * ready to create the privileged port, and will permanently drop
 209          * them when the port has been created (actually, when the connection
 210          * has been made, as we may need to create the port several times).
 211          */
 212         PRIV_END;
 213
 214 #ifdef HAVE_SETRLIMIT
 215         /* If we are installed setuid root be careful to not drop core. */
 216         if (original_real_uid != original_effective_uid) {
 217                 struct rlimit rlim;
 218                 rlim.rlim_cur = rlim.rlim_max = 0;
 219                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 220                         fatal("setrlimit failed: %.100s", strerror(errno));
 221         }
 222 #endif
 223         /* Get user data. */
 224         pw = getpwuid(original_real_uid);
 225         if (!pw) {
 226                 logit("You don't exist, go away!");
 227                 exit(255);
 228         }
 229         /* Take a copy of the returned structure. */
 230         pw = pwcopy(pw);
 231
 232         /*
 233          * Set our umask to something reasonable, as some files are created
 234          * with the default umask.  This will make them world-readable but
 235          * writable only by the owner, which is ok for all files for which we
 236          * don't set the modes explicitly.
 237          */
 238         umask(022);
 239
 240         /* Initialize option structure to indicate that no values have been set. */
 241         initialize_options(&options);
 242
 243         /* Parse command-line arguments. */
 244         host = NULL;
 245         /* need to set options.tcp_rcv_buf to 0 */
 246         options.tcp_rcv_buf = 0;
 247
 248 again:
 249         while ((opt = getopt(ac, av,
 250             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:MNO:PR:S:TVw:XYz")) != -1) {
 251                 switch (opt) {
 252                 case '1':
 253                         options.protocol = SSH_PROTO_1;
 254                         break;
 255                 case '2':
 256                         options.protocol = SSH_PROTO_2;
 257                         break;
 258                 case '4':
 259                         options.address_family = AF_INET;
 260                         break;
 261                 case '6':
 262                         options.address_family = AF_INET6;
 263                         break;
 264                 case 'n':
 265                         stdin_null_flag = 1;
 266                         break;
 267                 case 'f':
 268                         fork_after_authentication_flag = 1;
 269                         stdin_null_flag = 1;
 270                         break;
 271                 case 'x':
 272                         options.forward_x11 = 0;
 273                         break;
 274                 case 'X':
 275                         options.forward_x11 = 1;
 276                         break;
 277                 case 'Y':
 278                         options.forward_x11 = 1;
 279                         options.forward_x11_trusted = 1;
 280                         break;
 281                 case 'g':
 282                         options.gateway_ports = 1;
 283                         break;
 284                 case 'O':
 285                         if (strcmp(optarg, "check") == 0)
 286                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 287                         else if (strcmp(optarg, "exit") == 0)
 288                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 289                         else
 290                                 fatal("Invalid multiplex command.");
 291                         break;
 292                 case 'P':       /* deprecated */
 293                         options.use_privileged_port = 0;
 294                         break;
 295                 case 'a':
 296                         options.forward_agent = 0;
 297                         break;
 298                 case 'A':
 299                         options.forward_agent = 1;
 300                         break;
 301                 case 'k':
 302                         options.gss_deleg_creds = 0;
 303                         break;
 304                 case 'i':
 305                         if (stat(optarg, &st) < 0) {
 306                                 fprintf(stderr, "Warning: Identity file %s "
 307                                     "not accessible: %s.\n", optarg,
 308                                     strerror(errno));
 309                                 break;
 310                         }
 311                         if (options.num_identity_files >=
 312                             SSH_MAX_IDENTITY_FILES)
 313                                 fatal("Too many identity files specified "
 314                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 315                         options.identity_files[options.num_identity_files++] =
 316                             xstrdup(optarg);
 317                         break;
 318                 case 'I':
 319 #ifdef SMARTCARD
 320                         options.smartcard_device = xstrdup(optarg);
 321 #else
 322                         fprintf(stderr, "no support for smartcards.\n");
 323 #endif
 324                         break;
 325                 case 't':
 326                         if (tty_flag)
 327                                 force_tty_flag = 1;
 328                         tty_flag = 1;
 329                         break;
 330                 case 'v':
 331                         if (debug_flag == 0) {
 332                                 debug_flag = 1;
 333                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 334                         } else {
 335                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 336                                         options.log_level++;
 337                                 break;
 338                         }
 339                         /* FALLTHROUGH */
 340                 case 'V':
 341                         fprintf(stderr, "%s, %s\n",
 342                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 343                         if (opt == 'V')
 344                                 exit(0);
 345                         break;
 346                 case 'w':
 347                         if (options.tun_open == -1)
 348                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 349                         options.tun_local = a2tun(optarg, &options.tun_remote);
 350                         if (options.tun_local == SSH_TUNID_ERR) {
 351                                 fprintf(stderr, "Bad tun device '%s'\n", optarg);
 352                                 exit(255);
 353                         }
 354                         break;
 355                 case 'q':
 356                         options.log_level = SYSLOG_LEVEL_QUIET;
 357                         break;
 358                 case 'e':
 359                         if (optarg[0] == '^' && optarg[2] == 0 &&
 360                             (u_char) optarg[1] >= 64 &&
 361                             (u_char) optarg[1] < 128)
 362                                 options.escape_char = (u_char) optarg[1] & 31;
 363                         else if (strlen(optarg) == 1)
 364                                 options.escape_char = (u_char) optarg[0];
 365                         else if (strcmp(optarg, "none") == 0)
 366                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 367                         else {
 368                                 fprintf(stderr, "Bad escape character '%s'.\n",
 369                                     optarg);
 370                                 exit(255);
 371                         }
 372                         break;
 373                 case 'c':
 374                         if (ciphers_valid(optarg)) {
 375                                 /* SSH2 only */
 376                                 options.ciphers = xstrdup(optarg);
 377                                 options.cipher = SSH_CIPHER_INVALID;
 378                         } else {
 379                                 /* SSH1 only */
 380                                 options.cipher = cipher_number(optarg);
 381                                 if (options.cipher == -1) {
 382                                         fprintf(stderr,
 383                                             "Unknown cipher type '%s'\n",
 384                                             optarg);
 385                                         exit(255);
 386                                 }
 387                                 if (options.cipher == SSH_CIPHER_3DES)
 388                                         options.ciphers = "3des-cbc";
 389                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 390                                         options.ciphers = "blowfish-cbc";
 391                                 else
 392                                         options.ciphers = (char *)-1;
 393                         }
 394                         break;
 395                 case 'm':
 396                         if (mac_valid(optarg))
 397                                 options.macs = xstrdup(optarg);
 398                         else {
 399                                 fprintf(stderr, "Unknown mac type '%s'\n",
 400                                     optarg);
 401                                 exit(255);
 402                         }
 403                         break;
 404                 case 'M':
 405                         if (options.control_master == SSHCTL_MASTER_YES)
 406                                 options.control_master = SSHCTL_MASTER_ASK;
 407                         else
 408                                 options.control_master = SSHCTL_MASTER_YES;
 409                         break;
 410                 case 'p':
 411                         options.port = a2port(optarg);
 412                         if (options.port == 0) {
 413                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 414                                 exit(255);
 415                         }
 416                         break;
 417                 case 'l':
 418                         options.user = optarg;
 419                         break;
 420
 421                 case 'L':
 422                         if (parse_forward(&fwd, optarg))
 423                                 add_local_forward(&options, &fwd);
 424                         else {
 425                                 fprintf(stderr,
 426                                     "Bad local forwarding specification '%s'\n",
 427                                     optarg);
 428                                 exit(255);
 429                         }
 430                         break;
 431
 432                 case 'R':
 433                         if (parse_forward(&fwd, optarg)) {
 434                                 add_remote_forward(&options, &fwd);
 435                         } else {
 436                                 fprintf(stderr,
 437                                     "Bad remote forwarding specification "
 438                                     "'%s'\n", optarg);
 439                                 exit(255);
 440                         }
 441                         break;
 442
 443                 case 'D':
 444                         cp = p = xstrdup(optarg);
 445                         memset(&fwd, '\0', sizeof(fwd));
 446                         fwd.connect_host = "socks";
 447                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 448                                 fprintf(stderr, "Bad dynamic forwarding "
 449                                     "specification '%.100s'\n", optarg);
 450                                 exit(255);
 451                         }
 452                         if (cp != NULL) {
 453                                 fwd.listen_port = a2port(cp);
 454                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 455                         } else {
 456                                 fwd.listen_port = a2port(fwd.listen_host);
 457                                 fwd.listen_host = NULL;
 458                         }
 459
 460                         if (fwd.listen_port == 0) {
 461                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 462                                     optarg);
 463                                 exit(255);
 464                         }
 465                         add_local_forward(&options, &fwd);
 466                         xfree(p);
 467                         break;
 468
 469                 case 'C':
 470                         options.compression = 1;
 471                         break;
 472                 case 'N':
 473                         no_shell_flag = 1;
 474                         no_tty_flag = 1;
 475                         options.none_switch = 0;
 476                         break;
 477                 case 'T':
 478                         no_tty_flag = 1;
 479                         options.none_switch = 0;
 480                         break;
 481                 case 'o':
 482                         dummy = 1;
 483                         line = xstrdup(optarg);
 484                         if (process_config_line(&options, host ? host : "",
 485                             line, "command-line", 0, &dummy) != 0)
 486                                 exit(255);
 487                         xfree(line);
 488                         break;
 489                 case 's':
 490                         subsystem_flag = 1;
 491                         break;
 492                 case 'S':
 493                         if (options.control_path != NULL)
 494                                 free(options.control_path);
 495                         options.control_path = xstrdup(optarg);
 496                         break;
 497                 case 'b':
 498                         options.bind_address = optarg;
 499                         break;
 500                 case 'F':
 501                         config = optarg;
 502                         break;
 503                 case 'r':
 504                         options.tcp_rcv_buf = atoi(optarg) * 1024;
 505                         break;
 506                 case 'z':
 507                         /* make sure we can't turn on the none_switch */
 508                         /* if they try to force a no tty flag on a tty session */
 509                         if (!no_tty_flag) {
 510                                 options.none_switch = 1;
 511                         }
 512                         break;
 513
 514                 default:
 515                         usage();
 516                 }
 517         }
 518
 519         ac -= optind;
 520         av += optind;
 521
 522         if (ac > 0 && !host && **av != '-') {
 523                 if (strrchr(*av, '@')) {
 524                         p = xstrdup(*av);
 525                         cp = strrchr(p, '@');
 526                         if (cp == NULL || cp == p)
 527                                 usage();
 528                         options.user = p;
 529                         *cp = '\0';
 530                         host = ++cp;
 531                 } else
 532                         host = *av;
 533                 if (ac > 1) {
 534                         optind = optreset = 1;
 535                         goto again;
 536                 }
 537                 ac--, av++;
 538         }
 539
 540         /* Check that we got a host name. */
 541         if (!host)
 542                 usage();
 543
 544         SSLeay_add_all_algorithms();
 545         ERR_load_crypto_strings();
 546
 547         /* Initialize the command to execute on remote host. */
 548         buffer_init(&command);
 549
 550         /*
 551          * Save the command to execute on the remote host in a buffer. There
 552          * is no limit on the length of the command, except by the maximum
 553          * packet size.  Also sets the tty flag if there is no command.
 554          */
 555         if (!ac) {
 556                 /* No command specified - execute shell on a tty. */
 557                 tty_flag = 1;
 558                 if (subsystem_flag) {
 559                         fprintf(stderr,
 560                             "You must specify a subsystem to invoke.\n");
 561                         usage();
 562                 }
 563         } else {
 564                 /* A command has been specified.  Store it into the buffer. */
 565                 for (i = 0; i < ac; i++) {
 566                         if (i)
 567                                 buffer_append(&command, " ", 1);
 568                         buffer_append(&command, av[i], strlen(av[i]));
 569                 }
 570         }
 571
 572         /* Cannot fork to background if no command. */
 573         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 574                 fatal("Cannot fork into background without a command to execute.");
 575
 576         /* Allocate a tty by default if no command specified. */
 577         if (buffer_len(&command) == 0)
 578                 tty_flag = 1;
 579
 580         /* Force no tty */
 581         if (no_tty_flag)
 582                 tty_flag = 0;
 583         /* Do not allocate a tty if stdin is not a tty. */
 584         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 585                 if (tty_flag)
 586                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 587                 tty_flag = 0;
 588         }
 589
 590         /*
 591          * Initialize "log" output.  Since we are the client all output
 592          * actually goes to stderr.
 593          */
 594         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 595             SYSLOG_FACILITY_USER, 1);
 596
 597         /*
 598          * Read per-user configuration file.  Ignore the system wide config
 599          * file if the user specifies a config file on the command line.
 600          */
 601         if (config != NULL) {
 602                 if (!read_config_file(config, host, &options, 0))
 603                         fatal("Can't open user config file %.100s: "
 604                             "%.100s", config, strerror(errno));
 605         } else  {
 606             /*
 607              * Since the config file parsing code aborts if it sees
 608              * options it doesn't recognize, allow users to put
 609              * options specific to compile-time add-ons in alternate
 610              * config files so their primary config file will
 611              * interoperate SSH versions that don't support those
 612              * options.
 613              */
 614 #ifdef GSSAPI
 615                 snprintf(buf, sizeof buf, "%.100s/%.100s.gssapi", pw->pw_dir,
 616                     _PATH_SSH_USER_CONFFILE);
 617                 (void)read_config_file(buf, host, &options, 1);
 618 #ifdef GSI
 619                 snprintf(buf, sizeof buf, "%.100s/%.100s.gsi", pw->pw_dir,
 620                     _PATH_SSH_USER_CONFFILE);
 621                 (void)read_config_file(buf, host, &options, 1);
 622 #endif
 623 #if defined(KRB5)
 624                 snprintf(buf, sizeof buf, "%.100s/%.100s.krb", pw->pw_dir,
 625                     _PATH_SSH_USER_CONFFILE);
 626                 (void)read_config_file(buf, host, &options, 1);
 627 #endif
 628 #endif
 629                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 630                     _PATH_SSH_USER_CONFFILE);
 631                 (void)read_config_file(buf, host, &options, 1);
 632
 633                 /* Read systemwide configuration file after use config. */
 634                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 635                     &options, 0);
 636         }
 637
 638         /* Fill configuration defaults. */
 639         fill_default_options(&options);
 640
 641         channel_set_af(options.address_family);
 642
 643         /* reinit */
 644         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 645
 646         seed_rng();
 647
 648         if (options.user == NULL) {
 649                 options.user = xstrdup(pw->pw_name);
 650                 options.implicit = 1;
 651         }
 652         else options.implicit = 0;
 653
 654         if (options.hostname != NULL)
 655                 host = options.hostname;
 656
 657         /* force lowercase for hostkey matching */
 658         if (options.host_key_alias != NULL) {
 659                 for (p = options.host_key_alias; *p; p++)
 660                         if (isupper(*p))
 661                                 *p = tolower(*p);
 662         }
 663
 664         /* Get default port if port has not been set. */
 665         if (options.port == 0) {
 666                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 667                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 668         }
 669
 670         if (options.proxy_command != NULL &&
 671             strcmp(options.proxy_command, "none") == 0)
 672                 options.proxy_command = NULL;
 673         if (options.control_path != NULL &&
 674             strcmp(options.control_path, "none") == 0)
 675                 options.control_path = NULL;
 676
 677         if (options.control_path != NULL) {
 678                 snprintf(buf, sizeof(buf), "%d", options.port);
 679                 cp = tilde_expand_filename(options.control_path,
 680                     original_real_uid);
 681                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 682                     "r", options.user, (char *)NULL);
 683                 xfree(cp);
 684         }
 685         if (mux_command != 0 && options.control_path == NULL)
 686                 fatal("No ControlPath specified for \"-O\" command");
 687         if (options.control_path != NULL)
 688                 control_client(options.control_path);
 689
 690         /* Open a connection to the remote host. */
 691         if (ssh_connect(host, &hostaddr, options.port,
 692             options.address_family, options.connection_attempts,
 693 #ifdef HAVE_CYGWIN
 694             options.use_privileged_port,
 695 #else
 696             original_effective_uid == 0 && options.use_privileged_port,
 697 #endif
 698             options.proxy_command) != 0)
 699                 exit(255);
 700
 701         /*
 702          * If we successfully made the connection, load the host private key
 703          * in case we will need it later for combined rsa-rhosts
 704          * authentication. This must be done before releasing extra
 705          * privileges, because the file is only readable by root.
 706          * If we cannot access the private keys, load the public keys
 707          * instead and try to execute the ssh-keysign helper instead.
 708          */
 709         sensitive_data.nkeys = 0;
 710         sensitive_data.keys = NULL;
 711         sensitive_data.external_keysign = 0;
 712         if (options.rhosts_rsa_authentication ||
 713             options.hostbased_authentication) {
 714                 sensitive_data.nkeys = 3;
 715                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 716                     sizeof(Key));
 717
 718                 PRIV_START;
 719                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 720                     _PATH_HOST_KEY_FILE, "", NULL);
 721                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 722                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 723                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 724                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 725                 PRIV_END;
 726
 727                 if (options.hostbased_authentication == 1 &&
 728                     sensitive_data.keys[0] == NULL &&
 729                     sensitive_data.keys[1] == NULL &&
 730                     sensitive_data.keys[2] == NULL) {
 731                         sensitive_data.keys[1] = key_load_public(
 732                             _PATH_HOST_DSA_KEY_FILE, NULL);
 733                         sensitive_data.keys[2] = key_load_public(
 734                             _PATH_HOST_RSA_KEY_FILE, NULL);
 735                         sensitive_data.external_keysign = 1;
 736                 }
 737         }
 738         /*
 739          * Get rid of any extra privileges that we may have.  We will no
 740          * longer need them.  Also, extra privileges could make it very hard
 741          * to read identity files and other non-world-readable files from the
 742          * user's home directory if it happens to be on a NFS volume where
 743          * root is mapped to nobody.
 744          */
 745         if (original_effective_uid == 0) {
 746                 PRIV_START;
 747                 permanently_set_uid(pw);
 748         }
 749
 750         /*
 751          * Now that we are back to our own permissions, create ~/.ssh
 752          * directory if it doesn't already exist.
 753          */
 754         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 755         if (stat(buf, &st) < 0)
 756                 if (mkdir(buf, 0700) < 0)
 757                         error("Could not create directory '%.200s'.", buf);
 758
 759         /* load options.identity_files */
 760         load_public_identity_files();
 761
 762         /* Expand ~ in known host file names. */
 763         /* XXX mem-leaks: */
 764         options.system_hostfile =
 765             tilde_expand_filename(options.system_hostfile, original_real_uid);
 766         options.user_hostfile =
 767             tilde_expand_filename(options.user_hostfile, original_real_uid);
 768         options.system_hostfile2 =
 769             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 770         options.user_hostfile2 =
 771             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 772
 773         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 774
 775         /* Log into the remote system.  This never returns if the login fails. */
 776         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 777
 778         /* We no longer need the private host keys.  Clear them now. */
 779         if (sensitive_data.nkeys != 0) {
 780                 for (i = 0; i < sensitive_data.nkeys; i++) {
 781                         if (sensitive_data.keys[i] != NULL) {
 782                                 /* Destroys contents safely */
 783                                 debug3("clear hostkey %d", i);
 784                                 key_free(sensitive_data.keys[i]);
 785                                 sensitive_data.keys[i] = NULL;
 786                         }
 787                 }
 788                 xfree(sensitive_data.keys);
 789         }
 790         for (i = 0; i < options.num_identity_files; i++) {
 791                 if (options.identity_files[i]) {
 792                         xfree(options.identity_files[i]);
 793                         options.identity_files[i] = NULL;
 794                 }
 795                 if (options.identity_keys[i]) {
 796                         key_free(options.identity_keys[i]);
 797                         options.identity_keys[i] = NULL;
 798                 }
 799         }
 800
 801         exit_status = compat20 ? ssh_session2() : ssh_session();
 802         packet_close();
 803
 804         if (options.control_path != NULL && control_fd != -1)
 805                 unlink(options.control_path);
 806
 807         /*
 808          * Send SIGHUP to proxy command if used. We don't wait() in
 809          * case it hangs and instead rely on init to reap the child
 810          */
 811         if (proxy_command_pid > 1)
 812                 kill(proxy_command_pid, SIGHUP);
 813
 814         return exit_status;
 815 }
 816
 817 static void
 818 ssh_init_forwarding(void)
 819 {
 820         int success = 0;
 821         int i;
 822
 823         /* Initiate local TCP/IP port forwardings. */
 824         for (i = 0; i < options.num_local_forwards; i++) {
 825                 debug("Local connections to %.200s:%d forwarded to remote "
 826                     "address %.200s:%d",
 827                     (options.local_forwards[i].listen_host == NULL) ?
 828                     (options.gateway_ports ? "*" : "LOCALHOST") :
 829                     options.local_forwards[i].listen_host,
 830                     options.local_forwards[i].listen_port,
 831                     options.local_forwards[i].connect_host,
 832                     options.local_forwards[i].connect_port);
 833                 success += channel_setup_local_fwd_listener(
 834                     options.local_forwards[i].listen_host,
 835                     options.local_forwards[i].listen_port,
 836                     options.local_forwards[i].connect_host,
 837                     options.local_forwards[i].connect_port,
 838                     options.gateway_ports);
 839         }
 840         if (i > 0 && success == 0)
 841                 error("Could not request local forwarding.");
 842
 843         /* Initiate remote TCP/IP port forwardings. */
 844         for (i = 0; i < options.num_remote_forwards; i++) {
 845                 debug("Remote connections from %.200s:%d forwarded to "
 846                     "local address %.200s:%d",
 847                     (options.remote_forwards[i].listen_host == NULL) ?
 848                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 849                     options.remote_forwards[i].listen_port,
 850                     options.remote_forwards[i].connect_host,
 851                     options.remote_forwards[i].connect_port);
 852                 channel_request_remote_forwarding(
 853                     options.remote_forwards[i].listen_host,
 854                     options.remote_forwards[i].listen_port,
 855                     options.remote_forwards[i].connect_host,
 856                     options.remote_forwards[i].connect_port);
 857         }
 858 }
 859
 860 static void
 861 check_agent_present(void)
 862 {
 863         if (options.forward_agent) {
 864                 /* Clear agent forwarding if we don't have an agent. */
 865                 if (!ssh_agent_present())
 866                         options.forward_agent = 0;
 867         }
 868 }
 869
 870 static int
 871 ssh_session(void)
 872 {
 873         int type;
 874         int interactive = 0;
 875         int have_tty = 0;
 876         struct winsize ws;
 877         char *cp;
 878         const char *display;
 879
 880         /* Enable compression if requested. */
 881         if (options.compression) {
 882                 debug("Requesting compression at level %d.", options.compression_level);
 883
 884                 if (options.compression_level < 1 || options.compression_level > 9)
 885                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 886
 887                 /* Send the request. */
 888                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 889                 packet_put_int(options.compression_level);
 890                 packet_send();
 891                 packet_write_wait();
 892                 type = packet_read();
 893                 if (type == SSH_SMSG_SUCCESS)
 894                         packet_start_compression(options.compression_level);
 895                 else if (type == SSH_SMSG_FAILURE)
 896                         logit("Warning: Remote host refused compression.");
 897                 else
 898                         packet_disconnect("Protocol error waiting for compression response.");
 899         }
 900         /* Allocate a pseudo tty if appropriate. */
 901         if (tty_flag) {
 902                 debug("Requesting pty.");
 903
 904                 /* Start the packet. */
 905                 packet_start(SSH_CMSG_REQUEST_PTY);
 906
 907                 /* Store TERM in the packet.  There is no limit on the
 908                    length of the string. */
 909                 cp = getenv("TERM");
 910                 if (!cp)
 911                         cp = "";
 912                 packet_put_cstring(cp);
 913
 914                 /* Store window size in the packet. */
 915                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 916                         memset(&ws, 0, sizeof(ws));
 917                 packet_put_int(ws.ws_row);
 918                 packet_put_int(ws.ws_col);
 919                 packet_put_int(ws.ws_xpixel);
 920                 packet_put_int(ws.ws_ypixel);
 921
 922                 /* Store tty modes in the packet. */
 923                 tty_make_modes(fileno(stdin), NULL);
 924
 925                 /* Send the packet, and wait for it to leave. */
 926                 packet_send();
 927                 packet_write_wait();
 928
 929                 /* Read response from the server. */
 930                 type = packet_read();
 931                 if (type == SSH_SMSG_SUCCESS) {
 932                         interactive = 1;
 933                         have_tty = 1;
 934                 } else if (type == SSH_SMSG_FAILURE)
 935                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 936                 else
 937                         packet_disconnect("Protocol error waiting for pty request response.");
 938         }
 939         /* Request X11 forwarding if enabled and DISPLAY is set. */
 940         display = getenv("DISPLAY");
 941         if (options.forward_x11 && display != NULL) {
 942                 char *proto, *data;
 943                 /* Get reasonable local authentication information. */
 944                 client_x11_get_proto(display, options.xauth_location,
 945                     options.forward_x11_trusted, &proto, &data);
 946                 /* Request forwarding with authentication spoofing. */
 947                 debug("Requesting X11 forwarding with authentication spoofing.");
 948                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 949
 950                 /* Read response from the server. */
 951                 type = packet_read();
 952                 if (type == SSH_SMSG_SUCCESS) {
 953                         interactive = 1;
 954                 } else if (type == SSH_SMSG_FAILURE) {
 955                         logit("Warning: Remote host denied X11 forwarding.");
 956                 } else {
 957                         packet_disconnect("Protocol error waiting for X11 forwarding");
 958                 }
 959         }
 960         /* Tell the packet module whether this is an interactive session. */
 961         packet_set_interactive(interactive);
 962
 963         /* Request authentication agent forwarding if appropriate. */
 964         check_agent_present();
 965
 966         if (options.forward_agent) {
 967                 debug("Requesting authentication agent forwarding.");
 968                 auth_request_forwarding();
 969
 970                 /* Read response from the server. */
 971                 type = packet_read();
 972                 packet_check_eom();
 973                 if (type != SSH_SMSG_SUCCESS)
 974                         logit("Warning: Remote host denied authentication agent forwarding.");
 975         }
 976
 977         /* Initiate port forwardings. */
 978         ssh_init_forwarding();
 979
 980         /* If requested, let ssh continue in the background. */
 981         if (fork_after_authentication_flag)
 982                 if (daemon(1, 1) < 0)
 983                         fatal("daemon() failed: %.200s", strerror(errno));
 984
 985         /*
 986          * If a command was specified on the command line, execute the
 987          * command now. Otherwise request the server to start a shell.
 988          */
 989         if (buffer_len(&command) > 0) {
 990                 int len = buffer_len(&command);
 991                 if (len > 900)
 992                         len = 900;
 993                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 994                 packet_start(SSH_CMSG_EXEC_CMD);
 995                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 996                 packet_send();
 997                 packet_write_wait();
 998         } else {
 999                 debug("Requesting shell.");
1000                 packet_start(SSH_CMSG_EXEC_SHELL);
1001                 packet_send();
1002                 packet_write_wait();
1003         }
1004
1005         /* Enter the interactive session. */
1006         return client_loop(have_tty, tty_flag ?
1007             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1008 }
1009
1010 static void
1011 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1012 {
1013         int id, len;
1014
1015         id = packet_get_int();
1016         len = buffer_len(&command);
1017         if (len > 900)
1018                 len = 900;
1019         packet_check_eom();
1020         if (type == SSH2_MSG_CHANNEL_FAILURE)
1021                 fatal("Request for subsystem '%.*s' failed on channel %d",
1022                     len, (u_char *)buffer_ptr(&command), id);
1023 }
1024
1025 void
1026 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1027 {
1028         int i;
1029
1030         i = client_global_request_id++;
1031         if (i >= options.num_remote_forwards)
1032                 return;
1033         debug("remote forward %s for: listen %d, connect %s:%d",
1034             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1035             options.remote_forwards[i].listen_port,
1036             options.remote_forwards[i].connect_host,
1037             options.remote_forwards[i].connect_port);
1038         if (type == SSH2_MSG_REQUEST_FAILURE)
1039                 logit("Warning: remote port forwarding failed for listen "
1040                     "port %d", options.remote_forwards[i].listen_port);
1041 }
1042
1043 static void
1044 ssh_control_listener(void)
1045 {
1046         struct sockaddr_un addr;
1047         mode_t old_umask;
1048         int addr_len;
1049
1050         if (options.control_path == NULL ||
1051             options.control_master == SSHCTL_MASTER_NO)
1052                 return;
1053
1054         debug("setting up multiplex master socket");
1055
1056         memset(&addr, '\0', sizeof(addr));
1057         addr.sun_family = AF_UNIX;
1058         addr_len = offsetof(struct sockaddr_un, sun_path) +
1059             strlen(options.control_path) + 1;
1060
1061         if (strlcpy(addr.sun_path, options.control_path,
1062             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1063                 fatal("ControlPath too long");
1064
1065         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1066                 fatal("%s socket(): %s", __func__, strerror(errno));
1067
1068         old_umask = umask(0177);
1069         if (bind(control_fd, (struct sockaddr*)&addr, addr_len) == -1) {
1070                 control_fd = -1;
1071                 if (errno == EINVAL || errno == EADDRINUSE)
1072                         fatal("ControlSocket %s already exists",
1073                             options.control_path);
1074                 else
1075                         fatal("%s bind(): %s", __func__, strerror(errno));
1076         }
1077         umask(old_umask);
1078
1079         if (listen(control_fd, 64) == -1)
1080                 fatal("%s listen(): %s", __func__, strerror(errno));
1081
1082         set_nonblock(control_fd);
1083 }
1084
1085 /* request pty/x11/agent/tcpfwd/shell for channel */
1086 static void
1087 ssh_session2_setup(int id, void *arg)
1088 {
1089         extern char **environ;
1090         const char *display;
1091         int interactive = tty_flag;
1092
1093         display = getenv("DISPLAY");
1094         if (options.forward_x11 && display != NULL) {
1095                 char *proto, *data;
1096                 /* Get reasonable local authentication information. */
1097                 client_x11_get_proto(display, options.xauth_location,
1098                     options.forward_x11_trusted, &proto, &data);
1099                 /* Request forwarding with authentication spoofing. */
1100                 debug("Requesting X11 forwarding with authentication spoofing.");
1101                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1102                 interactive = 1;
1103                 /* XXX wait for reply */
1104         }
1105
1106         check_agent_present();
1107         if (options.forward_agent) {
1108                 debug("Requesting authentication agent forwarding.");
1109                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1110                 packet_send();
1111         }
1112
1113         if (options.tun_open != SSH_TUNMODE_NO) {
1114                 Channel *c;
1115                 int fd;
1116
1117                 debug("Requesting tun.");
1118                 if ((fd = tun_open(options.tun_local,
1119                     options.tun_open)) >= 0) {
1120                         c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1121                             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1122                             0, "tun", 1);
1123                         c->datagram = 1;
1124 #if defined(SSH_TUN_FILTER)
1125                         if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
1126                                 channel_register_filter(c->self, sys_tun_infilter,
1127                                     sys_tun_outfilter);
1128 #endif
1129                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1130                         packet_put_cstring("tun@openssh.com");
1131                         packet_put_int(c->self);
1132                         packet_put_int(c->local_window_max);
1133                         packet_put_int(c->local_maxpacket);
1134                         packet_put_int(options.tun_open);
1135                         packet_put_int(options.tun_remote);
1136                         packet_send();
1137                 }
1138         }
1139
1140         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1141             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1142
1143         packet_set_interactive(interactive);
1144 }
1145
1146 /* open new channel for a session */
1147 static int
1148 ssh_session2_open(void)
1149 {
1150         Channel *c;
1151         int window, packetmax, in, out, err;
1152
1153         if (stdin_null_flag) {
1154                 in = open(_PATH_DEVNULL, O_RDONLY);
1155         } else {
1156                 in = dup(STDIN_FILENO);
1157         }
1158         out = dup(STDOUT_FILENO);
1159         err = dup(STDERR_FILENO);
1160
1161         if (in < 0 || out < 0 || err < 0)
1162                 fatal("dup() in/out/err failed");
1163
1164         /* enable nonblocking unless tty */
1165         if (!isatty(in))
1166                 set_nonblock(in);
1167         if (!isatty(out))
1168                 set_nonblock(out);
1169         if (!isatty(err))
1170                 set_nonblock(err);
1171
1172         window = CHAN_SES_WINDOW_DEFAULT;
1173         packetmax = CHAN_SES_PACKET_DEFAULT;
1174         if (tty_flag) {
1175                 window = 4*CHAN_SES_PACKET_DEFAULT;
1176                 window >>= 1;
1177                 packetmax >>= 1;
1178         }
1179         c = channel_new(
1180             "session", SSH_CHANNEL_OPENING, in, out, err,
1181             window, packetmax, CHAN_EXTENDED_WRITE,
1182             "client-session", /*nonblock*/0);
1183         if (!tty_flag && (!(datafellows & SSH_BUG_LARGEWINDOW))) {
1184                 c->dynamic_window = 1;
1185         }
1186         debug3("ssh_session2_open: channel_new: %d", c->self);
1187
1188         channel_send_open(c->self);
1189         if (!no_shell_flag)
1190                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1191
1192         return c->self;
1193 }
1194
1195 static int
1196 ssh_session2(void)
1197 {
1198         int id = -1;
1199
1200         /* XXX should be pre-session */
1201         ssh_init_forwarding();
1202         ssh_control_listener();
1203
1204         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1205                 id = ssh_session2_open();
1206
1207         /* Execute a local command */
1208         if (options.local_command != NULL &&
1209             options.permit_local_command)
1210                 ssh_local_cmd(options.local_command);
1211
1212         /* If requested, let ssh continue in the background. */
1213         if (fork_after_authentication_flag)
1214                 if (daemon(1, 1) < 0)
1215                         fatal("daemon() failed: %.200s", strerror(errno));
1216
1217         return client_loop(tty_flag, tty_flag ?
1218             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1219 }
1220
1221 static void
1222 load_public_identity_files(void)
1223 {
1224         char *filename;
1225         int i = 0;
1226         Key *public;
1227 #ifdef SMARTCARD
1228         Key **keys;
1229
1230         if (options.smartcard_device != NULL &&
1231             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1232             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1233                 int count = 0;
1234                 for (i = 0; keys[i] != NULL; i++) {
1235                         count++;
1236                         memmove(&options.identity_files[1], &options.identity_files[0],
1237                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1238                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1239                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1240                         options.num_identity_files++;
1241                         options.identity_keys[0] = keys[i];
1242                         options.identity_files[0] = sc_get_key_label(keys[i]);
1243                 }
1244                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1245                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1246                 i = count;
1247                 xfree(keys);
1248         }
1249 #endif /* SMARTCARD */
1250         for (; i < options.num_identity_files; i++) {
1251                 filename = tilde_expand_filename(options.identity_files[i],
1252                     original_real_uid);
1253                 public = key_load_public(filename, NULL);
1254                 debug("identity file %s type %d", filename,
1255                     public ? public->type : -1);
1256                 xfree(options.identity_files[i]);
1257                 options.identity_files[i] = filename;
1258                 options.identity_keys[i] = public;
1259         }
1260 }
1261
1262 static void
1263 control_client_sighandler(int signo)
1264 {
1265         control_client_terminate = signo;
1266 }
1267
1268 static void
1269 control_client_sigrelay(int signo)
1270 {
1271         if (control_server_pid > 1)
1272                 kill(control_server_pid, signo);
1273 }
1274
1275 static int
1276 env_permitted(char *env)
1277 {
1278         int i;
1279         char name[1024], *cp;
1280
1281         strlcpy(name, env, sizeof(name));
1282         if ((cp = strchr(name, '=')) == NULL)
1283                 return (0);
1284
1285         *cp = '\0';
1286
1287         for (i = 0; i < options.num_send_env; i++)
1288                 if (match_pattern(name, options.send_env[i]))
1289                         return (1);
1290
1291         return (0);
1292 }
1293
1294 static void
1295 control_client(const char *path)
1296 {
1297         struct sockaddr_un addr;
1298         int i, r, fd, sock, exitval, num_env, addr_len;
1299         Buffer m;
1300         char *term;
1301         extern char **environ;
1302         u_int  flags;
1303
1304         if (mux_command == 0)
1305                 mux_command = SSHMUX_COMMAND_OPEN;
1306
1307         switch (options.control_master) {
1308         case SSHCTL_MASTER_AUTO:
1309         case SSHCTL_MASTER_AUTO_ASK:
1310                 debug("auto-mux: Trying existing master");
1311                 /* FALLTHROUGH */
1312         case SSHCTL_MASTER_NO:
1313                 break;
1314         default:
1315                 return;
1316         }
1317
1318         memset(&addr, '\0', sizeof(addr));
1319         addr.sun_family = AF_UNIX;
1320         addr_len = offsetof(struct sockaddr_un, sun_path) +
1321             strlen(path) + 1;
1322
1323         if (strlcpy(addr.sun_path, path,
1324             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1325                 fatal("ControlPath too long");
1326
1327         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1328                 fatal("%s socket(): %s", __func__, strerror(errno));
1329
1330         if (connect(sock, (struct sockaddr*)&addr, addr_len) == -1) {
1331                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1332                         fatal("Control socket connect(%.100s): %s", path,
1333                             strerror(errno));
1334                 }
1335                 if (errno == ENOENT)
1336                         debug("Control socket \"%.100s\" does not exist", path);
1337                 else {
1338                         error("Control socket connect(%.100s): %s", path,
1339                             strerror(errno));
1340                 }
1341                 close(sock);
1342                 return;
1343         }
1344
1345         if (stdin_null_flag) {
1346                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1347                         fatal("open(/dev/null): %s", strerror(errno));
1348                 if (dup2(fd, STDIN_FILENO) == -1)
1349                         fatal("dup2: %s", strerror(errno));
1350                 if (fd > STDERR_FILENO)
1351                         close(fd);
1352         }
1353
1354         term = getenv("TERM");
1355
1356         flags = 0;
1357         if (tty_flag)
1358                 flags |= SSHMUX_FLAG_TTY;
1359         if (subsystem_flag)
1360                 flags |= SSHMUX_FLAG_SUBSYS;
1361         if (options.forward_x11)
1362                 flags |= SSHMUX_FLAG_X11_FWD;
1363         if (options.forward_agent)
1364                 flags |= SSHMUX_FLAG_AGENT_FWD;
1365
1366         buffer_init(&m);
1367
1368         /* Send our command to server */
1369         buffer_put_int(&m, mux_command);
1370         buffer_put_int(&m, flags);
1371         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1372                 fatal("%s: msg_send", __func__);
1373         buffer_clear(&m);
1374
1375         /* Get authorisation status and PID of controlee */
1376         if (ssh_msg_recv(sock, &m) == -1)
1377                 fatal("%s: msg_recv", __func__);
1378         if (buffer_get_char(&m) != SSHMUX_VER)
1379                 fatal("%s: wrong version", __func__);
1380         if (buffer_get_int(&m) != 1)
1381                 fatal("Connection to master denied");
1382         control_server_pid = buffer_get_int(&m);
1383
1384         buffer_clear(&m);
1385
1386         switch (mux_command) {
1387         case SSHMUX_COMMAND_ALIVE_CHECK:
1388                 fprintf(stderr, "Master running (pid=%d)\r\n",
1389                     control_server_pid);
1390                 exit(0);
1391         case SSHMUX_COMMAND_TERMINATE:
1392                 fprintf(stderr, "Exit request sent.\r\n");
1393                 exit(0);
1394         case SSHMUX_COMMAND_OPEN:
1395                 /* continue below */
1396                 break;
1397         default:
1398                 fatal("silly mux_command %d", mux_command);
1399         }
1400
1401         /* SSHMUX_COMMAND_OPEN */
1402         buffer_put_cstring(&m, term ? term : "");
1403         buffer_append(&command, "\0", 1);
1404         buffer_put_cstring(&m, buffer_ptr(&command));
1405
1406         if (options.num_send_env == 0 || environ == NULL) {
1407                 buffer_put_int(&m, 0);
1408         } else {
1409                 /* Pass environment */
1410                 num_env = 0;
1411                 for (i = 0; environ[i] != NULL; i++)
1412                         if (env_permitted(environ[i]))
1413                                 num_env++; /* Count */
1414
1415                 buffer_put_int(&m, num_env);
1416
1417                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1418                         if (env_permitted(environ[i])) {
1419                                 num_env--;
1420                                 buffer_put_cstring(&m, environ[i]);
1421                         }
1422         }
1423
1424         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1425                 fatal("%s: msg_send", __func__);
1426
1427         mm_send_fd(sock, STDIN_FILENO);
1428         mm_send_fd(sock, STDOUT_FILENO);
1429         mm_send_fd(sock, STDERR_FILENO);
1430
1431         /* Wait for reply, so master has a chance to gather ttymodes */
1432         buffer_clear(&m);
1433         if (ssh_msg_recv(sock, &m) == -1)
1434                 fatal("%s: msg_recv", __func__);
1435         if (buffer_get_char(&m) != SSHMUX_VER)
1436                 fatal("%s: wrong version", __func__);
1437         buffer_free(&m);
1438
1439         signal(SIGHUP, control_client_sighandler);
1440         signal(SIGINT, control_client_sighandler);
1441         signal(SIGTERM, control_client_sighandler);
1442         signal(SIGWINCH, control_client_sigrelay);
1443
1444         if (tty_flag)
1445                 enter_raw_mode();
1446
1447         /* Stick around until the controlee closes the client_fd */
1448         exitval = 0;
1449         for (;!control_client_terminate;) {
1450                 r = read(sock, &exitval, sizeof(exitval));
1451                 if (r == 0) {
1452                         debug2("Received EOF from master");
1453                         break;
1454                 }
1455                 if (r > 0)
1456                         debug2("Received exit status from master %d", exitval);
1457                 if (r == -1 && errno != EINTR)
1458                         fatal("%s: read %s", __func__, strerror(errno));
1459         }
1460
1461         if (control_client_terminate)
1462                 debug2("Exiting on signal %d", control_client_terminate);
1463
1464         close(sock);
1465
1466         leave_raw_mode();
1467
1468         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1469                 fprintf(stderr, "Connection to master closed.\r\n");
1470
1471         exit(exitval);
1472 }