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 [-1246AaCfgkMNnqsTtVvXxY] [-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         );
 167         exit(255);
 168 }
 169
 170 static int ssh_session(void);
 171 static int ssh_session2(void);
 172 static void load_public_identity_files(void);
 173 static void control_client(const char *path);
 174
 175 /*
 176  * Main program for the ssh client.
 177  */
 178 int
 179 main(int ac, char **av)
 180 {
 181         int i, opt, exit_status;
 182         char *p, *cp, *line, buf[256];
 183         struct stat st;
 184         struct passwd *pw;
 185         int dummy;
 186         extern int optind, optreset;
 187         extern char *optarg;
 188         struct servent *sp;
 189         Forward fwd;
 190
 191         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 192         sanitise_stdfd();
 193
 194         __progname = ssh_get_progname(av[0]);
 195         init_rng();
 196
 197         /*
 198          * Save the original real uid.  It will be needed later (uid-swapping
 199          * may clobber the real uid).
 200          */
 201         original_real_uid = getuid();
 202         original_effective_uid = geteuid();
 203
 204         /*
 205          * Use uid-swapping to give up root privileges for the duration of
 206          * option processing.  We will re-instantiate the rights when we are
 207          * ready to create the privileged port, and will permanently drop
 208          * them when the port has been created (actually, when the connection
 209          * has been made, as we may need to create the port several times).
 210          */
 211         PRIV_END;
 212
 213 #ifdef HAVE_SETRLIMIT
 214         /* If we are installed setuid root be careful to not drop core. */
 215         if (original_real_uid != original_effective_uid) {
 216                 struct rlimit rlim;
 217                 rlim.rlim_cur = rlim.rlim_max = 0;
 218                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 219                         fatal("setrlimit failed: %.100s", strerror(errno));
 220         }
 221 #endif
 222         /* Get user data. */
 223         pw = getpwuid(original_real_uid);
 224         if (!pw) {
 225                 logit("You don't exist, go away!");
 226                 exit(255);
 227         }
 228         /* Take a copy of the returned structure. */
 229         pw = pwcopy(pw);
 230
 231         /*
 232          * Set our umask to something reasonable, as some files are created
 233          * with the default umask.  This will make them world-readable but
 234          * writable only by the owner, which is ok for all files for which we
 235          * don't set the modes explicitly.
 236          */
 237         umask(022);
 238
 239         /* Initialize option structure to indicate that no values have been set. */
 240         initialize_options(&options);
 241
 242         /* Parse command-line arguments. */
 243         host = NULL;
 244
 245 again:
 246         while ((opt = getopt(ac, av,
 247             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:MNO:PR:S:TVw:XY")) != -1) {
 248                 switch (opt) {
 249                 case '1':
 250                         options.protocol = SSH_PROTO_1;
 251                         break;
 252                 case '2':
 253                         options.protocol = SSH_PROTO_2;
 254                         break;
 255                 case '4':
 256                         options.address_family = AF_INET;
 257                         break;
 258                 case '6':
 259                         options.address_family = AF_INET6;
 260                         break;
 261                 case 'n':
 262                         stdin_null_flag = 1;
 263                         break;
 264                 case 'f':
 265                         fork_after_authentication_flag = 1;
 266                         stdin_null_flag = 1;
 267                         break;
 268                 case 'x':
 269                         options.forward_x11 = 0;
 270                         break;
 271                 case 'X':
 272                         options.forward_x11 = 1;
 273                         break;
 274                 case 'Y':
 275                         options.forward_x11 = 1;
 276                         options.forward_x11_trusted = 1;
 277                         break;
 278                 case 'g':
 279                         options.gateway_ports = 1;
 280                         break;
 281                 case 'O':
 282                         if (strcmp(optarg, "check") == 0)
 283                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 284                         else if (strcmp(optarg, "exit") == 0)
 285                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 286                         else
 287                                 fatal("Invalid multiplex command.");
 288                         break;
 289                 case 'P':       /* deprecated */
 290                         options.use_privileged_port = 0;
 291                         break;
 292                 case 'a':
 293                         options.forward_agent = 0;
 294                         break;
 295                 case 'A':
 296                         options.forward_agent = 1;
 297                         break;
 298                 case 'k':
 299                         options.gss_deleg_creds = 0;
 300                         break;
 301                 case 'i':
 302                         if (stat(optarg, &st) < 0) {
 303                                 fprintf(stderr, "Warning: Identity file %s "
 304                                     "not accessible: %s.\n", optarg,
 305                                     strerror(errno));
 306                                 break;
 307                         }
 308                         if (options.num_identity_files >=
 309                             SSH_MAX_IDENTITY_FILES)
 310                                 fatal("Too many identity files specified "
 311                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 312                         options.identity_files[options.num_identity_files++] =
 313                             xstrdup(optarg);
 314                         break;
 315                 case 'I':
 316 #ifdef SMARTCARD
 317                         options.smartcard_device = xstrdup(optarg);
 318 #else
 319                         fprintf(stderr, "no support for smartcards.\n");
 320 #endif
 321                         break;
 322                 case 't':
 323                         if (tty_flag)
 324                                 force_tty_flag = 1;
 325                         tty_flag = 1;
 326                         break;
 327                 case 'v':
 328                         if (debug_flag == 0) {
 329                                 debug_flag = 1;
 330                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 331                         } else {
 332                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 333                                         options.log_level++;
 334                                 break;
 335                         }
 336                         /* FALLTHROUGH */
 337                 case 'V':
 338                         fprintf(stderr, "%s, %s\n",
 339                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 340                         if (opt == 'V')
 341                                 exit(0);
 342                         break;
 343                 case 'w':
 344                         if (options.tun_open == -1)
 345                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 346                         options.tun_local = a2tun(optarg, &options.tun_remote);
 347                         if (options.tun_local == SSH_TUNID_ERR) {
 348                                 fprintf(stderr, "Bad tun device '%s'\n", optarg);
 349                                 exit(255);
 350                         }
 351                         break;
 352                 case 'q':
 353                         options.log_level = SYSLOG_LEVEL_QUIET;
 354                         break;
 355                 case 'e':
 356                         if (optarg[0] == '^' && optarg[2] == 0 &&
 357                             (u_char) optarg[1] >= 64 &&
 358                             (u_char) optarg[1] < 128)
 359                                 options.escape_char = (u_char) optarg[1] & 31;
 360                         else if (strlen(optarg) == 1)
 361                                 options.escape_char = (u_char) optarg[0];
 362                         else if (strcmp(optarg, "none") == 0)
 363                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 364                         else {
 365                                 fprintf(stderr, "Bad escape character '%s'.\n",
 366                                     optarg);
 367                                 exit(255);
 368                         }
 369                         break;
 370                 case 'c':
 371                         if (ciphers_valid(optarg)) {
 372                                 /* SSH2 only */
 373                                 options.ciphers = xstrdup(optarg);
 374                                 options.cipher = SSH_CIPHER_INVALID;
 375                         } else {
 376                                 /* SSH1 only */
 377                                 options.cipher = cipher_number(optarg);
 378                                 if (options.cipher == -1) {
 379                                         fprintf(stderr,
 380                                             "Unknown cipher type '%s'\n",
 381                                             optarg);
 382                                         exit(255);
 383                                 }
 384                                 if (options.cipher == SSH_CIPHER_3DES)
 385                                         options.ciphers = "3des-cbc";
 386                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 387                                         options.ciphers = "blowfish-cbc";
 388                                 else
 389                                         options.ciphers = (char *)-1;
 390                         }
 391                         break;
 392                 case 'm':
 393                         if (mac_valid(optarg))
 394                                 options.macs = xstrdup(optarg);
 395                         else {
 396                                 fprintf(stderr, "Unknown mac type '%s'\n",
 397                                     optarg);
 398                                 exit(255);
 399                         }
 400                         break;
 401                 case 'M':
 402                         if (options.control_master == SSHCTL_MASTER_YES)
 403                                 options.control_master = SSHCTL_MASTER_ASK;
 404                         else
 405                                 options.control_master = SSHCTL_MASTER_YES;
 406                         break;
 407                 case 'p':
 408                         options.port = a2port(optarg);
 409                         if (options.port == 0) {
 410                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 411                                 exit(255);
 412                         }
 413                         break;
 414                 case 'l':
 415                         options.user = optarg;
 416                         break;
 417
 418                 case 'L':
 419                         if (parse_forward(&fwd, optarg))
 420                                 add_local_forward(&options, &fwd);
 421                         else {
 422                                 fprintf(stderr,
 423                                     "Bad local forwarding specification '%s'\n",
 424                                     optarg);
 425                                 exit(255);
 426                         }
 427                         break;
 428
 429                 case 'R':
 430                         if (parse_forward(&fwd, optarg)) {
 431                                 add_remote_forward(&options, &fwd);
 432                         } else {
 433                                 fprintf(stderr,
 434                                     "Bad remote forwarding specification "
 435                                     "'%s'\n", optarg);
 436                                 exit(255);
 437                         }
 438                         break;
 439
 440                 case 'D':
 441                         cp = p = xstrdup(optarg);
 442                         memset(&fwd, '\0', sizeof(fwd));
 443                         fwd.connect_host = "socks";
 444                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 445                                 fprintf(stderr, "Bad dynamic forwarding "
 446                                     "specification '%.100s'\n", optarg);
 447                                 exit(255);
 448                         }
 449                         if (cp != NULL) {
 450                                 fwd.listen_port = a2port(cp);
 451                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 452                         } else {
 453                                 fwd.listen_port = a2port(fwd.listen_host);
 454                                 fwd.listen_host = NULL;
 455                         }
 456
 457                         if (fwd.listen_port == 0) {
 458                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 459                                     optarg);
 460                                 exit(255);
 461                         }
 462                         add_local_forward(&options, &fwd);
 463                         xfree(p);
 464                         break;
 465
 466                 case 'C':
 467                         options.compression = 1;
 468                         break;
 469                 case 'N':
 470                         no_shell_flag = 1;
 471                         no_tty_flag = 1;
 472                         options.none_switch = 0;
 473                         break;
 474                 case 'T':
 475                         no_tty_flag = 1;
 476                         options.none_switch = 0;
 477                         break;
 478                 case 'o':
 479                         dummy = 1;
 480                         line = xstrdup(optarg);
 481                         if (process_config_line(&options, host ? host : "",
 482                             line, "command-line", 0, &dummy) != 0)
 483                                 exit(255);
 484                         xfree(line);
 485                         break;
 486                 case 's':
 487                         subsystem_flag = 1;
 488                         break;
 489                 case 'S':
 490                         if (options.control_path != NULL)
 491                                 free(options.control_path);
 492                         options.control_path = xstrdup(optarg);
 493                         break;
 494                 case 'b':
 495                         options.bind_address = optarg;
 496                         break;
 497                 case 'F':
 498                         config = optarg;
 499                         break;
 500                 case 'z':
 501                         /* make sure we can't turn on the none_switch */
 502                         /* if they try to force a no tty flag on a tty session */
 503                         if (!no_tty_flag) {
 504                                 options.none_switch = 1;
 505                         }
 506                         break;
 507
 508                 default:
 509                         usage();
 510                 }
 511         }
 512
 513         ac -= optind;
 514         av += optind;
 515
 516         if (ac > 0 && !host && **av != '-') {
 517                 if (strrchr(*av, '@')) {
 518                         p = xstrdup(*av);
 519                         cp = strrchr(p, '@');
 520                         if (cp == NULL || cp == p)
 521                                 usage();
 522                         options.user = p;
 523                         *cp = '\0';
 524                         host = ++cp;
 525                 } else
 526                         host = *av;
 527                 if (ac > 1) {
 528                         optind = optreset = 1;
 529                         goto again;
 530                 }
 531                 ac--, av++;
 532         }
 533
 534         /* Check that we got a host name. */
 535         if (!host)
 536                 usage();
 537
 538         SSLeay_add_all_algorithms();
 539         ERR_load_crypto_strings();
 540
 541         /* Initialize the command to execute on remote host. */
 542         buffer_init(&command);
 543
 544         /*
 545          * Save the command to execute on the remote host in a buffer. There
 546          * is no limit on the length of the command, except by the maximum
 547          * packet size.  Also sets the tty flag if there is no command.
 548          */
 549         if (!ac) {
 550                 /* No command specified - execute shell on a tty. */
 551                 tty_flag = 1;
 552                 if (subsystem_flag) {
 553                         fprintf(stderr,
 554                             "You must specify a subsystem to invoke.\n");
 555                         usage();
 556                 }
 557         } else {
 558                 /* A command has been specified.  Store it into the buffer. */
 559                 for (i = 0; i < ac; i++) {
 560                         if (i)
 561                                 buffer_append(&command, " ", 1);
 562                         buffer_append(&command, av[i], strlen(av[i]));
 563                 }
 564         }
 565
 566         /* Cannot fork to background if no command. */
 567         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 568                 fatal("Cannot fork into background without a command to execute.");
 569
 570         /* Allocate a tty by default if no command specified. */
 571         if (buffer_len(&command) == 0)
 572                 tty_flag = 1;
 573
 574         /* Force no tty */
 575         if (no_tty_flag)
 576                 tty_flag = 0;
 577         /* Do not allocate a tty if stdin is not a tty. */
 578         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 579                 if (tty_flag)
 580                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 581                 tty_flag = 0;
 582         }
 583
 584         /*
 585          * Initialize "log" output.  Since we are the client all output
 586          * actually goes to stderr.
 587          */
 588         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 589             SYSLOG_FACILITY_USER, 1);
 590
 591         /*
 592          * Read per-user configuration file.  Ignore the system wide config
 593          * file if the user specifies a config file on the command line.
 594          */
 595         if (config != NULL) {
 596                 if (!read_config_file(config, host, &options, 0))
 597                         fatal("Can't open user config file %.100s: "
 598                             "%.100s", config, strerror(errno));
 599         } else  {
 600             /*
 601              * Since the config file parsing code aborts if it sees
 602              * options it doesn't recognize, allow users to put
 603              * options specific to compile-time add-ons in alternate
 604              * config files so their primary config file will
 605              * interoperate SSH versions that don't support those
 606              * options.
 607              */
 608 #ifdef GSSAPI
 609                 snprintf(buf, sizeof buf, "%.100s/%.100s.gssapi", pw->pw_dir,
 610                     _PATH_SSH_USER_CONFFILE);
 611                 (void)read_config_file(buf, host, &options, 1);
 612 #ifdef GSI
 613                 snprintf(buf, sizeof buf, "%.100s/%.100s.gsi", pw->pw_dir,
 614                     _PATH_SSH_USER_CONFFILE);
 615                 (void)read_config_file(buf, host, &options, 1);
 616 #endif
 617 #if defined(KRB5)
 618                 snprintf(buf, sizeof buf, "%.100s/%.100s.krb", pw->pw_dir,
 619                     _PATH_SSH_USER_CONFFILE);
 620                 (void)read_config_file(buf, host, &options, 1);
 621 #endif
 622 #endif
 623                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 624                     _PATH_SSH_USER_CONFFILE);
 625                 (void)read_config_file(buf, host, &options, 1);
 626
 627                 /* Read systemwide configuration file after use config. */
 628                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 629                     &options, 0);
 630         }
 631
 632         /* Fill configuration defaults. */
 633         fill_default_options(&options);
 634
 635         channel_set_af(options.address_family);
 636
 637         /* reinit */
 638         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 639
 640         seed_rng();
 641
 642         if (options.user == NULL) {
 643                 options.user = xstrdup(pw->pw_name);
 644                 options.implicit = 1;
 645         }
 646         else options.implicit = 0;
 647
 648         if (options.hostname != NULL)
 649                 host = options.hostname;
 650
 651         /* force lowercase for hostkey matching */
 652         if (options.host_key_alias != NULL) {
 653                 for (p = options.host_key_alias; *p; p++)
 654                         if (isupper(*p))
 655                                 *p = tolower(*p);
 656         }
 657
 658         /* Get default port if port has not been set. */
 659         if (options.port == 0) {
 660                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 661                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 662         }
 663
 664         if (options.proxy_command != NULL &&
 665             strcmp(options.proxy_command, "none") == 0)
 666                 options.proxy_command = NULL;
 667         if (options.control_path != NULL &&
 668             strcmp(options.control_path, "none") == 0)
 669                 options.control_path = NULL;
 670
 671         if (options.control_path != NULL) {
 672                 snprintf(buf, sizeof(buf), "%d", options.port);
 673                 cp = tilde_expand_filename(options.control_path,
 674                     original_real_uid);
 675                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 676                     "r", options.user, (char *)NULL);
 677                 xfree(cp);
 678         }
 679         if (mux_command != 0 && options.control_path == NULL)
 680                 fatal("No ControlPath specified for \"-O\" command");
 681         if (options.control_path != NULL)
 682                 control_client(options.control_path);
 683
 684         /* Open a connection to the remote host. */
 685         if (ssh_connect(host, &hostaddr, options.port,
 686             options.address_family, options.connection_attempts,
 687 #ifdef HAVE_CYGWIN
 688             options.use_privileged_port,
 689 #else
 690             original_effective_uid == 0 && options.use_privileged_port,
 691 #endif
 692             options.proxy_command) != 0)
 693                 exit(255);
 694
 695         /*
 696          * If we successfully made the connection, load the host private key
 697          * in case we will need it later for combined rsa-rhosts
 698          * authentication. This must be done before releasing extra
 699          * privileges, because the file is only readable by root.
 700          * If we cannot access the private keys, load the public keys
 701          * instead and try to execute the ssh-keysign helper instead.
 702          */
 703         sensitive_data.nkeys = 0;
 704         sensitive_data.keys = NULL;
 705         sensitive_data.external_keysign = 0;
 706         if (options.rhosts_rsa_authentication ||
 707             options.hostbased_authentication) {
 708                 sensitive_data.nkeys = 3;
 709                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 710                     sizeof(Key));
 711
 712                 PRIV_START;
 713                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 714                     _PATH_HOST_KEY_FILE, "", NULL);
 715                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 716                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 717                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 718                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 719                 PRIV_END;
 720
 721                 if (options.hostbased_authentication == 1 &&
 722                     sensitive_data.keys[0] == NULL &&
 723                     sensitive_data.keys[1] == NULL &&
 724                     sensitive_data.keys[2] == NULL) {
 725                         sensitive_data.keys[1] = key_load_public(
 726                             _PATH_HOST_DSA_KEY_FILE, NULL);
 727                         sensitive_data.keys[2] = key_load_public(
 728                             _PATH_HOST_RSA_KEY_FILE, NULL);
 729                         sensitive_data.external_keysign = 1;
 730                 }
 731         }
 732         /*
 733          * Get rid of any extra privileges that we may have.  We will no
 734          * longer need them.  Also, extra privileges could make it very hard
 735          * to read identity files and other non-world-readable files from the
 736          * user's home directory if it happens to be on a NFS volume where
 737          * root is mapped to nobody.
 738          */
 739         if (original_effective_uid == 0) {
 740                 PRIV_START;
 741                 permanently_set_uid(pw);
 742         }
 743
 744         /*
 745          * Now that we are back to our own permissions, create ~/.ssh
 746          * directory if it doesn't already exist.
 747          */
 748         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 749         if (stat(buf, &st) < 0)
 750                 if (mkdir(buf, 0700) < 0)
 751                         error("Could not create directory '%.200s'.", buf);
 752
 753         /* load options.identity_files */
 754         load_public_identity_files();
 755
 756         /* Expand ~ in known host file names. */
 757         /* XXX mem-leaks: */
 758         options.system_hostfile =
 759             tilde_expand_filename(options.system_hostfile, original_real_uid);
 760         options.user_hostfile =
 761             tilde_expand_filename(options.user_hostfile, original_real_uid);
 762         options.system_hostfile2 =
 763             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 764         options.user_hostfile2 =
 765             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 766
 767         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 768
 769         /* Log into the remote system.  This never returns if the login fails. */
 770         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 771
 772         /* We no longer need the private host keys.  Clear them now. */
 773         if (sensitive_data.nkeys != 0) {
 774                 for (i = 0; i < sensitive_data.nkeys; i++) {
 775                         if (sensitive_data.keys[i] != NULL) {
 776                                 /* Destroys contents safely */
 777                                 debug3("clear hostkey %d", i);
 778                                 key_free(sensitive_data.keys[i]);
 779                                 sensitive_data.keys[i] = NULL;
 780                         }
 781                 }
 782                 xfree(sensitive_data.keys);
 783         }
 784         for (i = 0; i < options.num_identity_files; i++) {
 785                 if (options.identity_files[i]) {
 786                         xfree(options.identity_files[i]);
 787                         options.identity_files[i] = NULL;
 788                 }
 789                 if (options.identity_keys[i]) {
 790                         key_free(options.identity_keys[i]);
 791                         options.identity_keys[i] = NULL;
 792                 }
 793         }
 794
 795         exit_status = compat20 ? ssh_session2() : ssh_session();
 796         packet_close();
 797
 798         if (options.control_path != NULL && control_fd != -1)
 799                 unlink(options.control_path);
 800
 801         /*
 802          * Send SIGHUP to proxy command if used. We don't wait() in
 803          * case it hangs and instead rely on init to reap the child
 804          */
 805         if (proxy_command_pid > 1)
 806                 kill(proxy_command_pid, SIGHUP);
 807
 808         return exit_status;
 809 }
 810
 811 static void
 812 ssh_init_forwarding(void)
 813 {
 814         int success = 0;
 815         int i;
 816
 817         /* Initiate local TCP/IP port forwardings. */
 818         for (i = 0; i < options.num_local_forwards; i++) {
 819                 debug("Local connections to %.200s:%d forwarded to remote "
 820                     "address %.200s:%d",
 821                     (options.local_forwards[i].listen_host == NULL) ?
 822                     (options.gateway_ports ? "*" : "LOCALHOST") :
 823                     options.local_forwards[i].listen_host,
 824                     options.local_forwards[i].listen_port,
 825                     options.local_forwards[i].connect_host,
 826                     options.local_forwards[i].connect_port);
 827                 success += channel_setup_local_fwd_listener(
 828                     options.local_forwards[i].listen_host,
 829                     options.local_forwards[i].listen_port,
 830                     options.local_forwards[i].connect_host,
 831                     options.local_forwards[i].connect_port,
 832                     options.gateway_ports, options.hpn_disabled,
 833                     options.hpn_buffer_size);
 834         }
 835         if (i > 0 && success == 0)
 836                 error("Could not request local forwarding.");
 837
 838         /* Initiate remote TCP/IP port forwardings. */
 839         for (i = 0; i < options.num_remote_forwards; i++) {
 840                 debug("Remote connections from %.200s:%d forwarded to "
 841                     "local address %.200s:%d",
 842                     (options.remote_forwards[i].listen_host == NULL) ?
 843                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 844                     options.remote_forwards[i].listen_port,
 845                     options.remote_forwards[i].connect_host,
 846                     options.remote_forwards[i].connect_port);
 847                 channel_request_remote_forwarding(
 848                     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         }
 853 }
 854
 855 static void
 856 check_agent_present(void)
 857 {
 858         if (options.forward_agent) {
 859                 /* Clear agent forwarding if we don't have an agent. */
 860                 if (!ssh_agent_present())
 861                         options.forward_agent = 0;
 862         }
 863 }
 864
 865 static int
 866 ssh_session(void)
 867 {
 868         int type;
 869         int interactive = 0;
 870         int have_tty = 0;
 871         struct winsize ws;
 872         char *cp;
 873         const char *display;
 874
 875         /* Enable compression if requested. */
 876         if (options.compression) {
 877                 debug("Requesting compression at level %d.", options.compression_level);
 878
 879                 if (options.compression_level < 1 || options.compression_level > 9)
 880                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 881
 882                 /* Send the request. */
 883                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 884                 packet_put_int(options.compression_level);
 885                 packet_send();
 886                 packet_write_wait();
 887                 type = packet_read();
 888                 if (type == SSH_SMSG_SUCCESS)
 889                         packet_start_compression(options.compression_level);
 890                 else if (type == SSH_SMSG_FAILURE)
 891                         logit("Warning: Remote host refused compression.");
 892                 else
 893                         packet_disconnect("Protocol error waiting for compression response.");
 894         }
 895         /* Allocate a pseudo tty if appropriate. */
 896         if (tty_flag) {
 897                 debug("Requesting pty.");
 898
 899                 /* Start the packet. */
 900                 packet_start(SSH_CMSG_REQUEST_PTY);
 901
 902                 /* Store TERM in the packet.  There is no limit on the
 903                    length of the string. */
 904                 cp = getenv("TERM");
 905                 if (!cp)
 906                         cp = "";
 907                 packet_put_cstring(cp);
 908
 909                 /* Store window size in the packet. */
 910                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 911                         memset(&ws, 0, sizeof(ws));
 912                 packet_put_int(ws.ws_row);
 913                 packet_put_int(ws.ws_col);
 914                 packet_put_int(ws.ws_xpixel);
 915                 packet_put_int(ws.ws_ypixel);
 916
 917                 /* Store tty modes in the packet. */
 918                 tty_make_modes(fileno(stdin), NULL);
 919
 920                 /* Send the packet, and wait for it to leave. */
 921                 packet_send();
 922                 packet_write_wait();
 923
 924                 /* Read response from the server. */
 925                 type = packet_read();
 926                 if (type == SSH_SMSG_SUCCESS) {
 927                         interactive = 1;
 928                         have_tty = 1;
 929                 } else if (type == SSH_SMSG_FAILURE)
 930                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 931                 else
 932                         packet_disconnect("Protocol error waiting for pty request response.");
 933         }
 934         /* Request X11 forwarding if enabled and DISPLAY is set. */
 935         display = getenv("DISPLAY");
 936         if (options.forward_x11 && display != NULL) {
 937                 char *proto, *data;
 938                 /* Get reasonable local authentication information. */
 939                 client_x11_get_proto(display, options.xauth_location,
 940                     options.forward_x11_trusted, &proto, &data);
 941                 /* Request forwarding with authentication spoofing. */
 942                 debug("Requesting X11 forwarding with authentication spoofing.");
 943                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 944
 945                 /* Read response from the server. */
 946                 type = packet_read();
 947                 if (type == SSH_SMSG_SUCCESS) {
 948                         interactive = 1;
 949                 } else if (type == SSH_SMSG_FAILURE) {
 950                         logit("Warning: Remote host denied X11 forwarding.");
 951                 } else {
 952                         packet_disconnect("Protocol error waiting for X11 forwarding");
 953                 }
 954         }
 955         /* Tell the packet module whether this is an interactive session. */
 956         packet_set_interactive(interactive);
 957
 958         /* Request authentication agent forwarding if appropriate. */
 959         check_agent_present();
 960
 961         if (options.forward_agent) {
 962                 debug("Requesting authentication agent forwarding.");
 963                 auth_request_forwarding();
 964
 965                 /* Read response from the server. */
 966                 type = packet_read();
 967                 packet_check_eom();
 968                 if (type != SSH_SMSG_SUCCESS)
 969                         logit("Warning: Remote host denied authentication agent forwarding.");
 970         }
 971
 972         /* Initiate port forwardings. */
 973         ssh_init_forwarding();
 974
 975         /* If requested, let ssh continue in the background. */
 976         if (fork_after_authentication_flag)
 977                 if (daemon(1, 1) < 0)
 978                         fatal("daemon() failed: %.200s", strerror(errno));
 979
 980         /*
 981          * If a command was specified on the command line, execute the
 982          * command now. Otherwise request the server to start a shell.
 983          */
 984         if (buffer_len(&command) > 0) {
 985                 int len = buffer_len(&command);
 986                 if (len > 900)
 987                         len = 900;
 988                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 989                 packet_start(SSH_CMSG_EXEC_CMD);
 990                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 991                 packet_send();
 992                 packet_write_wait();
 993         } else {
 994                 debug("Requesting shell.");
 995                 packet_start(SSH_CMSG_EXEC_SHELL);
 996                 packet_send();
 997                 packet_write_wait();
 998         }
 999
1000         /* Enter the interactive session. */
1001         return client_loop(have_tty, tty_flag ?
1002             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1003 }
1004
1005 static void
1006 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1007 {
1008         int id, len;
1009
1010         id = packet_get_int();
1011         len = buffer_len(&command);
1012         if (len > 900)
1013                 len = 900;
1014         packet_check_eom();
1015         if (type == SSH2_MSG_CHANNEL_FAILURE)
1016                 fatal("Request for subsystem '%.*s' failed on channel %d",
1017                     len, (u_char *)buffer_ptr(&command), id);
1018 }
1019
1020 void
1021 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1022 {
1023         int i;
1024
1025         i = client_global_request_id++;
1026         if (i >= options.num_remote_forwards)
1027                 return;
1028         debug("remote forward %s for: listen %d, connect %s:%d",
1029             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1030             options.remote_forwards[i].listen_port,
1031             options.remote_forwards[i].connect_host,
1032             options.remote_forwards[i].connect_port);
1033         if (type == SSH2_MSG_REQUEST_FAILURE)
1034                 logit("Warning: remote port forwarding failed for listen "
1035                     "port %d", options.remote_forwards[i].listen_port);
1036 }
1037
1038 static void
1039 ssh_control_listener(void)
1040 {
1041         struct sockaddr_un addr;
1042         mode_t old_umask;
1043         int addr_len;
1044
1045         if (options.control_path == NULL ||
1046             options.control_master == SSHCTL_MASTER_NO)
1047                 return;
1048
1049         debug("setting up multiplex master socket");
1050
1051         memset(&addr, '\0', sizeof(addr));
1052         addr.sun_family = AF_UNIX;
1053         addr_len = offsetof(struct sockaddr_un, sun_path) +
1054             strlen(options.control_path) + 1;
1055
1056         if (strlcpy(addr.sun_path, options.control_path,
1057             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1058                 fatal("ControlPath too long");
1059
1060         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1061                 fatal("%s socket(): %s", __func__, strerror(errno));
1062
1063         old_umask = umask(0177);
1064         if (bind(control_fd, (struct sockaddr*)&addr, addr_len) == -1) {
1065                 control_fd = -1;
1066                 if (errno == EINVAL || errno == EADDRINUSE)
1067                         fatal("ControlSocket %s already exists",
1068                             options.control_path);
1069                 else
1070                         fatal("%s bind(): %s", __func__, strerror(errno));
1071         }
1072         umask(old_umask);
1073
1074         if (listen(control_fd, 64) == -1)
1075                 fatal("%s listen(): %s", __func__, strerror(errno));
1076
1077         set_nonblock(control_fd);
1078 }
1079
1080 /* request pty/x11/agent/tcpfwd/shell for channel */
1081 static void
1082 ssh_session2_setup(int id, void *arg)
1083 {
1084         extern char **environ;
1085         const char *display;
1086         int interactive = tty_flag;
1087
1088         display = getenv("DISPLAY");
1089         if (options.forward_x11 && display != NULL) {
1090                 char *proto, *data;
1091                 /* Get reasonable local authentication information. */
1092                 client_x11_get_proto(display, options.xauth_location,
1093                     options.forward_x11_trusted, &proto, &data);
1094                 /* Request forwarding with authentication spoofing. */
1095                 debug("Requesting X11 forwarding with authentication spoofing.");
1096                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1097                 interactive = 1;
1098                 /* XXX wait for reply */
1099         }
1100
1101         check_agent_present();
1102         if (options.forward_agent) {
1103                 debug("Requesting authentication agent forwarding.");
1104                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1105                 packet_send();
1106         }
1107
1108         if (options.tun_open != SSH_TUNMODE_NO) {
1109                 Channel *c;
1110                 int fd;
1111
1112                 debug("Requesting tun.");
1113                 if ((fd = tun_open(options.tun_local,
1114                     options.tun_open)) >= 0) {
1115                         if(options.hpn_disabled)
1116                                 c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1117                                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1118                                     0, "tun", 1);
1119                         else
1120                                 c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1121                                     options.hpn_buffer_size, 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         if(options.hpn_disabled)
1173                 window = CHAN_SES_WINDOW_DEFAULT;
1174         else
1175                 window = options.hpn_buffer_size;
1176         packetmax = CHAN_SES_PACKET_DEFAULT;
1177         if (tty_flag) {
1178                 window = 4*CHAN_SES_PACKET_DEFAULT;
1179                 window >>= 1;
1180                 packetmax >>= 1;
1181         }
1182         c = channel_new(
1183             "session", SSH_CHANNEL_OPENING, in, out, err,
1184             window, packetmax, CHAN_EXTENDED_WRITE,
1185             "client-session", /*nonblock*/0);
1186         if ((options.tcp_rcv_buf_poll > 0) && (!options.hpn_disabled)) {
1187                 c->dynamic_window = 1;
1188                 debug ("Enabled Dynamic Window Scaling\n");
1189         }
1190         debug3("ssh_session2_open: channel_new: %d", c->self);
1191
1192         channel_send_open(c->self);
1193         if (!no_shell_flag)
1194                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1195
1196         return c->self;
1197 }
1198
1199 static int
1200 ssh_session2(void)
1201 {
1202         int id = -1;
1203
1204         /* XXX should be pre-session */
1205         ssh_init_forwarding();
1206         ssh_control_listener();
1207
1208         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1209                 id = ssh_session2_open();
1210
1211         /* Execute a local command */
1212         if (options.local_command != NULL &&
1213             options.permit_local_command)
1214                 ssh_local_cmd(options.local_command);
1215
1216         /* If requested, let ssh continue in the background. */
1217         if (fork_after_authentication_flag)
1218                 if (daemon(1, 1) < 0)
1219                         fatal("daemon() failed: %.200s", strerror(errno));
1220
1221         return client_loop(tty_flag, tty_flag ?
1222             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1223 }
1224
1225 static void
1226 load_public_identity_files(void)
1227 {
1228         char *filename;
1229         int i = 0;
1230         Key *public;
1231 #ifdef SMARTCARD
1232         Key **keys;
1233
1234         if (options.smartcard_device != NULL &&
1235             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1236             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1237                 int count = 0;
1238                 for (i = 0; keys[i] != NULL; i++) {
1239                         count++;
1240                         memmove(&options.identity_files[1], &options.identity_files[0],
1241                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1242                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1243                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1244                         options.num_identity_files++;
1245                         options.identity_keys[0] = keys[i];
1246                         options.identity_files[0] = sc_get_key_label(keys[i]);
1247                 }
1248                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1249                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1250                 i = count;
1251                 xfree(keys);
1252         }
1253 #endif /* SMARTCARD */
1254         for (; i < options.num_identity_files; i++) {
1255                 filename = tilde_expand_filename(options.identity_files[i],
1256                     original_real_uid);
1257                 public = key_load_public(filename, NULL);
1258                 debug("identity file %s type %d", filename,
1259                     public ? public->type : -1);
1260                 xfree(options.identity_files[i]);
1261                 options.identity_files[i] = filename;
1262                 options.identity_keys[i] = public;
1263         }
1264 }
1265
1266 static void
1267 control_client_sighandler(int signo)
1268 {
1269         control_client_terminate = signo;
1270 }
1271
1272 static void
1273 control_client_sigrelay(int signo)
1274 {
1275         if (control_server_pid > 1)
1276                 kill(control_server_pid, signo);
1277 }
1278
1279 static int
1280 env_permitted(char *env)
1281 {
1282         int i;
1283         char name[1024], *cp;
1284
1285         strlcpy(name, env, sizeof(name));
1286         if ((cp = strchr(name, '=')) == NULL)
1287                 return (0);
1288
1289         *cp = '\0';
1290
1291         for (i = 0; i < options.num_send_env; i++)
1292                 if (match_pattern(name, options.send_env[i]))
1293                         return (1);
1294
1295         return (0);
1296 }
1297
1298 static void
1299 control_client(const char *path)
1300 {
1301         struct sockaddr_un addr;
1302         int i, r, fd, sock, exitval, num_env, addr_len;
1303         Buffer m;
1304         char *term;
1305         extern char **environ;
1306         u_int  flags;
1307
1308         if (mux_command == 0)
1309                 mux_command = SSHMUX_COMMAND_OPEN;
1310
1311         switch (options.control_master) {
1312         case SSHCTL_MASTER_AUTO:
1313         case SSHCTL_MASTER_AUTO_ASK:
1314                 debug("auto-mux: Trying existing master");
1315                 /* FALLTHROUGH */
1316         case SSHCTL_MASTER_NO:
1317                 break;
1318         default:
1319                 return;
1320         }
1321
1322         memset(&addr, '\0', sizeof(addr));
1323         addr.sun_family = AF_UNIX;
1324         addr_len = offsetof(struct sockaddr_un, sun_path) +
1325             strlen(path) + 1;
1326
1327         if (strlcpy(addr.sun_path, path,
1328             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1329                 fatal("ControlPath too long");
1330
1331         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1332                 fatal("%s socket(): %s", __func__, strerror(errno));
1333
1334         if (connect(sock, (struct sockaddr*)&addr, addr_len) == -1) {
1335                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1336                         fatal("Control socket connect(%.100s): %s", path,
1337                             strerror(errno));
1338                 }
1339                 if (errno == ENOENT)
1340                         debug("Control socket \"%.100s\" does not exist", path);
1341                 else {
1342                         error("Control socket connect(%.100s): %s", path,
1343                             strerror(errno));
1344                 }
1345                 close(sock);
1346                 return;
1347         }
1348
1349         if (stdin_null_flag) {
1350                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1351                         fatal("open(/dev/null): %s", strerror(errno));
1352                 if (dup2(fd, STDIN_FILENO) == -1)
1353                         fatal("dup2: %s", strerror(errno));
1354                 if (fd > STDERR_FILENO)
1355                         close(fd);
1356         }
1357
1358         term = getenv("TERM");
1359
1360         flags = 0;
1361         if (tty_flag)
1362                 flags |= SSHMUX_FLAG_TTY;
1363         if (subsystem_flag)
1364                 flags |= SSHMUX_FLAG_SUBSYS;
1365         if (options.forward_x11)
1366                 flags |= SSHMUX_FLAG_X11_FWD;
1367         if (options.forward_agent)
1368                 flags |= SSHMUX_FLAG_AGENT_FWD;
1369         if (options.num_local_forwards > 0)
1370                 flags |= SSHMUX_FLAG_PORTFORWARD;
1371         buffer_init(&m);
1372
1373         /* Send our command to server */
1374         buffer_put_int(&m, mux_command);
1375         buffer_put_int(&m, flags);
1376         if (options.num_local_forwards > 0)
1377         {
1378                 if (options.local_forwards[0].listen_host == NULL)
1379                         buffer_put_string(&m,"LOCALHOST",11);
1380                 else
1381                         buffer_put_string(&m,options.local_forwards[0].listen_host,512);
1382                 buffer_put_int(&m,options.local_forwards[0].listen_port);
1383                 buffer_put_string(&m,options.local_forwards[0].connect_host,512);
1384                 buffer_put_int(&m,options.local_forwards[0].connect_port);
1385         }
1386         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1387                 fatal("%s: msg_send", __func__);
1388         buffer_clear(&m);
1389
1390         /* Get authorisation status and PID of controlee */
1391         if (ssh_msg_recv(sock, &m) == -1)
1392                 fatal("%s: msg_recv", __func__);
1393         if (buffer_get_char(&m) != SSHMUX_VER)
1394                 fatal("%s: wrong version", __func__);
1395         if (buffer_get_int(&m) != 1)
1396                 fatal("Connection to master denied");
1397         control_server_pid = buffer_get_int(&m);
1398
1399         buffer_clear(&m);
1400
1401         switch (mux_command) {
1402         case SSHMUX_COMMAND_ALIVE_CHECK:
1403                 fprintf(stderr, "Master running (pid=%d)\r\n",
1404                     control_server_pid);
1405                 exit(0);
1406         case SSHMUX_COMMAND_TERMINATE:
1407                 fprintf(stderr, "Exit request sent.\r\n");
1408                 exit(0);
1409         case SSHMUX_COMMAND_OPEN:
1410                 /* continue below */
1411                 break;
1412         default:
1413                 fatal("silly mux_command %d", mux_command);
1414         }
1415
1416         /* SSHMUX_COMMAND_OPEN */
1417         buffer_put_cstring(&m, term ? term : "");
1418         buffer_append(&command, "\0", 1);
1419         buffer_put_cstring(&m, buffer_ptr(&command));
1420
1421         if (options.num_send_env == 0 || environ == NULL) {
1422                 buffer_put_int(&m, 0);
1423         } else {
1424                 /* Pass environment */
1425                 num_env = 0;
1426                 for (i = 0; environ[i] != NULL; i++)
1427                         if (env_permitted(environ[i]))
1428                                 num_env++; /* Count */
1429
1430                 buffer_put_int(&m, num_env);
1431
1432                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1433                         if (env_permitted(environ[i])) {
1434                                 num_env--;
1435                                 buffer_put_cstring(&m, environ[i]);
1436                         }
1437         }
1438
1439         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1440                 fatal("%s: msg_send", __func__);
1441
1442         mm_send_fd(sock, STDIN_FILENO);
1443         mm_send_fd(sock, STDOUT_FILENO);
1444         mm_send_fd(sock, STDERR_FILENO);
1445
1446         /* Wait for reply, so master has a chance to gather ttymodes */
1447         buffer_clear(&m);
1448         if (ssh_msg_recv(sock, &m) == -1)
1449                 fatal("%s: msg_recv", __func__);
1450         if (buffer_get_char(&m) != SSHMUX_VER)
1451                 fatal("%s: wrong version", __func__);
1452         buffer_free(&m);
1453
1454         signal(SIGHUP, control_client_sighandler);
1455         signal(SIGINT, control_client_sighandler);
1456         signal(SIGTERM, control_client_sighandler);
1457         signal(SIGWINCH, control_client_sigrelay);
1458
1459         if (tty_flag)
1460                 enter_raw_mode();
1461
1462         /* Stick around until the controlee closes the client_fd */
1463         exitval = 0;
1464         for (;!control_client_terminate;) {
1465                 r = read(sock, &exitval, sizeof(exitval));
1466                 if (r == 0) {
1467                         debug2("Received EOF from master");
1468                         break;
1469                 }
1470                 if (r > 0)
1471                         debug2("Received exit status from master %d", exitval);
1472                 if (r == -1 && errno != EINTR)
1473                         fatal("%s: read %s", __func__, strerror(errno));
1474         }
1475
1476         if (control_client_terminate)
1477                 debug2("Exiting on signal %d", control_client_terminate);
1478
1479         close(sock);
1480
1481         leave_raw_mode();
1482
1483         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1484                 fprintf(stderr, "Connection to master closed.\r\n");
1485
1486         exit(exitval);
1487 }