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_pathnames();
 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
 246 again:
 247         while ((opt = getopt(ac, av,
 248             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:MNO:PR:S:TVw:XY")) != -1) {
 249                 switch (opt) {
 250                 case '1':
 251                         options.protocol = SSH_PROTO_1;
 252                         break;
 253                 case '2':
 254                         options.protocol = SSH_PROTO_2;
 255                         break;
 256                 case '4':
 257                         options.address_family = AF_INET;
 258                         break;
 259                 case '6':
 260                         options.address_family = AF_INET6;
 261                         break;
 262                 case 'n':
 263                         stdin_null_flag = 1;
 264                         break;
 265                 case 'f':
 266                         fork_after_authentication_flag = 1;
 267                         stdin_null_flag = 1;
 268                         break;
 269                 case 'x':
 270                         options.forward_x11 = 0;
 271                         break;
 272                 case 'X':
 273                         options.forward_x11 = 1;
 274                         break;
 275                 case 'Y':
 276                         options.forward_x11 = 1;
 277                         options.forward_x11_trusted = 1;
 278                         break;
 279                 case 'g':
 280                         options.gateway_ports = 1;
 281                         break;
 282                 case 'O':
 283                         if (strcmp(optarg, "check") == 0)
 284                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 285                         else if (strcmp(optarg, "exit") == 0)
 286                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 287                         else
 288                                 fatal("Invalid multiplex command.");
 289                         break;
 290                 case 'P':       /* deprecated */
 291                         options.use_privileged_port = 0;
 292                         break;
 293                 case 'a':
 294                         options.forward_agent = 0;
 295                         break;
 296                 case 'A':
 297                         options.forward_agent = 1;
 298                         break;
 299                 case 'k':
 300                         options.gss_deleg_creds = 0;
 301                         break;
 302                 case 'i':
 303                         if (stat(optarg, &st) < 0) {
 304                                 fprintf(stderr, "Warning: Identity file %s "
 305                                     "not accessible: %s.\n", optarg,
 306                                     strerror(errno));
 307                                 break;
 308                         }
 309                         if (options.num_identity_files >=
 310                             SSH_MAX_IDENTITY_FILES)
 311                                 fatal("Too many identity files specified "
 312                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 313                         options.identity_files[options.num_identity_files++] =
 314                             xstrdup(optarg);
 315                         break;
 316                 case 'I':
 317 #ifdef SMARTCARD
 318                         options.smartcard_device = xstrdup(optarg);
 319 #else
 320                         fprintf(stderr, "no support for smartcards.\n");
 321 #endif
 322                         break;
 323                 case 't':
 324                         if (tty_flag)
 325                                 force_tty_flag = 1;
 326                         tty_flag = 1;
 327                         break;
 328                 case 'v':
 329                         if (debug_flag == 0) {
 330                                 debug_flag = 1;
 331                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 332                         } else {
 333                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 334                                         options.log_level++;
 335                                 break;
 336                         }
 337                         /* FALLTHROUGH */
 338                 case 'V':
 339                         fprintf(stderr, "%s, %s\n",
 340                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 341                         if (opt == 'V')
 342                                 exit(0);
 343                         break;
 344                 case 'w':
 345                         if (options.tun_open == -1)
 346                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 347                         options.tun_local = a2tun(optarg, &options.tun_remote);
 348                         if (options.tun_local == SSH_TUNID_ERR) {
 349                                 fprintf(stderr, "Bad tun device '%s'\n", optarg);
 350                                 exit(255);
 351                         }
 352                         break;
 353                 case 'q':
 354                         options.log_level = SYSLOG_LEVEL_QUIET;
 355                         break;
 356                 case 'e':
 357                         if (optarg[0] == '^' && optarg[2] == 0 &&
 358                             (u_char) optarg[1] >= 64 &&
 359                             (u_char) optarg[1] < 128)
 360                                 options.escape_char = (u_char) optarg[1] & 31;
 361                         else if (strlen(optarg) == 1)
 362                                 options.escape_char = (u_char) optarg[0];
 363                         else if (strcmp(optarg, "none") == 0)
 364                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 365                         else {
 366                                 fprintf(stderr, "Bad escape character '%s'.\n",
 367                                     optarg);
 368                                 exit(255);
 369                         }
 370                         break;
 371                 case 'c':
 372                         if (ciphers_valid(optarg)) {
 373                                 /* SSH2 only */
 374                                 options.ciphers = xstrdup(optarg);
 375                                 options.cipher = SSH_CIPHER_INVALID;
 376                         } else {
 377                                 /* SSH1 only */
 378                                 options.cipher = cipher_number(optarg);
 379                                 if (options.cipher == -1) {
 380                                         fprintf(stderr,
 381                                             "Unknown cipher type '%s'\n",
 382                                             optarg);
 383                                         exit(255);
 384                                 }
 385                                 if (options.cipher == SSH_CIPHER_3DES)
 386                                         options.ciphers = "3des-cbc";
 387                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 388                                         options.ciphers = "blowfish-cbc";
 389                                 else
 390                                         options.ciphers = (char *)-1;
 391                         }
 392                         break;
 393                 case 'm':
 394                         if (mac_valid(optarg))
 395                                 options.macs = xstrdup(optarg);
 396                         else {
 397                                 fprintf(stderr, "Unknown mac type '%s'\n",
 398                                     optarg);
 399                                 exit(255);
 400                         }
 401                         break;
 402                 case 'M':
 403                         if (options.control_master == SSHCTL_MASTER_YES)
 404                                 options.control_master = SSHCTL_MASTER_ASK;
 405                         else
 406                                 options.control_master = SSHCTL_MASTER_YES;
 407                         break;
 408                 case 'p':
 409                         options.port = a2port(optarg);
 410                         if (options.port == 0) {
 411                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 412                                 exit(255);
 413                         }
 414                         break;
 415                 case 'l':
 416                         options.user = optarg;
 417                         break;
 418
 419                 case 'L':
 420                         if (parse_forward(&fwd, optarg))
 421                                 add_local_forward(&options, &fwd);
 422                         else {
 423                                 fprintf(stderr,
 424                                     "Bad local forwarding specification '%s'\n",
 425                                     optarg);
 426                                 exit(255);
 427                         }
 428                         break;
 429
 430                 case 'R':
 431                         if (parse_forward(&fwd, optarg)) {
 432                                 add_remote_forward(&options, &fwd);
 433                         } else {
 434                                 fprintf(stderr,
 435                                     "Bad remote forwarding specification "
 436                                     "'%s'\n", optarg);
 437                                 exit(255);
 438                         }
 439                         break;
 440
 441                 case 'D':
 442                         cp = p = xstrdup(optarg);
 443                         memset(&fwd, '\0', sizeof(fwd));
 444                         fwd.connect_host = "socks";
 445                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 446                                 fprintf(stderr, "Bad dynamic forwarding "
 447                                     "specification '%.100s'\n", optarg);
 448                                 exit(255);
 449                         }
 450                         if (cp != NULL) {
 451                                 fwd.listen_port = a2port(cp);
 452                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 453                         } else {
 454                                 fwd.listen_port = a2port(fwd.listen_host);
 455                                 fwd.listen_host = NULL;
 456                         }
 457
 458                         if (fwd.listen_port == 0) {
 459                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 460                                     optarg);
 461                                 exit(255);
 462                         }
 463                         add_local_forward(&options, &fwd);
 464                         xfree(p);
 465                         break;
 466
 467                 case 'C':
 468                         options.compression = 1;
 469                         break;
 470                 case 'N':
 471                         no_shell_flag = 1;
 472                         no_tty_flag = 1;
 473                         options.none_switch = 0;
 474                         break;
 475                 case 'T':
 476                         no_tty_flag = 1;
 477                         options.none_switch = 0;
 478                         break;
 479                 case 'o':
 480                         dummy = 1;
 481                         line = xstrdup(optarg);
 482                         if (process_config_line(&options, host ? host : "",
 483                             line, "command-line", 0, &dummy) != 0)
 484                                 exit(255);
 485                         xfree(line);
 486                         break;
 487                 case 's':
 488                         subsystem_flag = 1;
 489                         break;
 490                 case 'S':
 491                         if (options.control_path != NULL)
 492                                 free(options.control_path);
 493                         options.control_path = xstrdup(optarg);
 494                         break;
 495                 case 'b':
 496                         options.bind_address = optarg;
 497                         break;
 498                 case 'F':
 499                         config = optarg;
 500                         break;
 501                 case 'z':
 502                         /* make sure we can't turn on the none_switch */
 503                         /* if they try to force a no tty flag on a tty session */
 504                         if (!no_tty_flag) {
 505                                 options.none_switch = 1;
 506                         }
 507                         break;
 508
 509                 default:
 510                         usage();
 511                 }
 512         }
 513
 514         ac -= optind;
 515         av += optind;
 516
 517         if (ac > 0 && !host && **av != '-') {
 518                 if (strrchr(*av, '@')) {
 519                         p = xstrdup(*av);
 520                         cp = strrchr(p, '@');
 521                         if (cp == NULL || cp == p)
 522                                 usage();
 523                         options.user = p;
 524                         *cp = '\0';
 525                         host = ++cp;
 526                 } else
 527                         host = *av;
 528                 if (ac > 1) {
 529                         optind = optreset = 1;
 530                         goto again;
 531                 }
 532                 ac--, av++;
 533         }
 534
 535         /* Check that we got a host name. */
 536         if (!host)
 537                 usage();
 538
 539         SSLeay_add_all_algorithms();
 540         ERR_load_crypto_strings();
 541
 542         /* Initialize the command to execute on remote host. */
 543         buffer_init(&command);
 544
 545         /*
 546          * Save the command to execute on the remote host in a buffer. There
 547          * is no limit on the length of the command, except by the maximum
 548          * packet size.  Also sets the tty flag if there is no command.
 549          */
 550         if (!ac) {
 551                 /* No command specified - execute shell on a tty. */
 552                 tty_flag = 1;
 553                 if (subsystem_flag) {
 554                         fprintf(stderr,
 555                             "You must specify a subsystem to invoke.\n");
 556                         usage();
 557                 }
 558         } else {
 559                 /* A command has been specified.  Store it into the buffer. */
 560                 for (i = 0; i < ac; i++) {
 561                         if (i)
 562                                 buffer_append(&command, " ", 1);
 563                         buffer_append(&command, av[i], strlen(av[i]));
 564                 }
 565         }
 566
 567         /* Cannot fork to background if no command. */
 568         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 569                 fatal("Cannot fork into background without a command to execute.");
 570
 571         /* Allocate a tty by default if no command specified. */
 572         if (buffer_len(&command) == 0)
 573                 tty_flag = 1;
 574
 575         /* Force no tty */
 576         if (no_tty_flag)
 577                 tty_flag = 0;
 578         /* Do not allocate a tty if stdin is not a tty. */
 579         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 580                 if (tty_flag)
 581                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 582                 tty_flag = 0;
 583         }
 584
 585         /*
 586          * Initialize "log" output.  Since we are the client all output
 587          * actually goes to stderr.
 588          */
 589         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 590             SYSLOG_FACILITY_USER, 1);
 591
 592         /*
 593          * Read per-user configuration file.  Ignore the system wide config
 594          * file if the user specifies a config file on the command line.
 595          */
 596         if (config != NULL) {
 597                 if (!read_config_file(config, host, &options, 0))
 598                         fatal("Can't open user config file %.100s: "
 599                             "%.100s", config, strerror(errno));
 600         } else  {
 601             /*
 602              * Since the config file parsing code aborts if it sees
 603              * options it doesn't recognize, allow users to put
 604              * options specific to compile-time add-ons in alternate
 605              * config files so their primary config file will
 606              * interoperate SSH versions that don't support those
 607              * options.
 608              */
 609 #ifdef GSSAPI
 610                 snprintf(buf, sizeof buf, "%.100s/%.100s.gssapi", pw->pw_dir,
 611                     _PATH_SSH_USER_CONFFILE);
 612                 (void)read_config_file(buf, host, &options, 1);
 613 #ifdef GSI
 614                 snprintf(buf, sizeof buf, "%.100s/%.100s.gsi", pw->pw_dir,
 615                     _PATH_SSH_USER_CONFFILE);
 616                 (void)read_config_file(buf, host, &options, 1);
 617 #endif
 618 #if defined(KRB5)
 619                 snprintf(buf, sizeof buf, "%.100s/%.100s.krb", pw->pw_dir,
 620                     _PATH_SSH_USER_CONFFILE);
 621                 (void)read_config_file(buf, host, &options, 1);
 622 #endif
 623 #endif
 624                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 625                     _PATH_SSH_USER_CONFFILE);
 626                 (void)read_config_file(buf, host, &options, 1);
 627
 628                 /* Read systemwide configuration file after use config. */
 629                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 630                     &options, 0);
 631         }
 632
 633         /* Fill configuration defaults. */
 634         fill_default_options(&options);
 635
 636         channel_set_af(options.address_family);
 637
 638         /* reinit */
 639         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 640
 641         seed_rng();
 642
 643         if (options.user == NULL) {
 644                 options.user = xstrdup(pw->pw_name);
 645                 options.implicit = 1;
 646         }
 647         else options.implicit = 0;
 648
 649         if (options.hostname != NULL)
 650                 host = options.hostname;
 651
 652         /* force lowercase for hostkey matching */
 653         if (options.host_key_alias != NULL) {
 654                 for (p = options.host_key_alias; *p; p++)
 655                         if (isupper(*p))
 656                                 *p = tolower(*p);
 657         }
 658
 659         /* Get default port if port has not been set. */
 660         if (options.port == 0) {
 661                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 662                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 663         }
 664
 665         if (options.proxy_command != NULL &&
 666             strcmp(options.proxy_command, "none") == 0)
 667                 options.proxy_command = NULL;
 668         if (options.control_path != NULL &&
 669             strcmp(options.control_path, "none") == 0)
 670                 options.control_path = NULL;
 671
 672         if (options.control_path != NULL) {
 673                 snprintf(buf, sizeof(buf), "%d", options.port);
 674                 cp = tilde_expand_filename(options.control_path,
 675                     original_real_uid);
 676                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 677                     "r", options.user, (char *)NULL);
 678                 xfree(cp);
 679         }
 680         if (mux_command != 0 && options.control_path == NULL)
 681                 fatal("No ControlPath specified for \"-O\" command");
 682         if (options.control_path != NULL)
 683                 control_client(options.control_path);
 684
 685         /* Open a connection to the remote host. */
 686         if (ssh_connect(host, &hostaddr, options.port,
 687             options.address_family, options.connection_attempts,
 688 #ifdef HAVE_CYGWIN
 689             options.use_privileged_port,
 690 #else
 691             original_effective_uid == 0 && options.use_privileged_port,
 692 #endif
 693             options.proxy_command) != 0)
 694                 exit(255);
 695
 696         /*
 697          * If we successfully made the connection, load the host private key
 698          * in case we will need it later for combined rsa-rhosts
 699          * authentication. This must be done before releasing extra
 700          * privileges, because the file is only readable by root.
 701          * If we cannot access the private keys, load the public keys
 702          * instead and try to execute the ssh-keysign helper instead.
 703          */
 704         sensitive_data.nkeys = 0;
 705         sensitive_data.keys = NULL;
 706         sensitive_data.external_keysign = 0;
 707         if (options.rhosts_rsa_authentication ||
 708             options.hostbased_authentication) {
 709                 sensitive_data.nkeys = 3;
 710                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 711                     sizeof(Key));
 712
 713                 PRIV_START;
 714                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 715                     _PATH_HOST_KEY_FILE, "", NULL);
 716                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 717                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 718                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 719                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 720                 PRIV_END;
 721
 722                 if (options.hostbased_authentication == 1 &&
 723                     sensitive_data.keys[0] == NULL &&
 724                     sensitive_data.keys[1] == NULL &&
 725                     sensitive_data.keys[2] == NULL) {
 726                         sensitive_data.keys[1] = key_load_public(
 727                             _PATH_HOST_DSA_KEY_FILE, NULL);
 728                         sensitive_data.keys[2] = key_load_public(
 729                             _PATH_HOST_RSA_KEY_FILE, NULL);
 730                         sensitive_data.external_keysign = 1;
 731                 }
 732         }
 733         /*
 734          * Get rid of any extra privileges that we may have.  We will no
 735          * longer need them.  Also, extra privileges could make it very hard
 736          * to read identity files and other non-world-readable files from the
 737          * user's home directory if it happens to be on a NFS volume where
 738          * root is mapped to nobody.
 739          */
 740         if (original_effective_uid == 0) {
 741                 PRIV_START;
 742                 permanently_set_uid(pw);
 743         }
 744
 745         /*
 746          * Now that we are back to our own permissions, create ~/.ssh
 747          * directory if it doesn't already exist.
 748          */
 749         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 750         if (stat(buf, &st) < 0)
 751                 if (mkdir(buf, 0700) < 0)
 752                         error("Could not create directory '%.200s'.", buf);
 753
 754         /* load options.identity_files */
 755         load_public_identity_files();
 756
 757         /* Expand ~ in known host file names. */
 758         /* XXX mem-leaks: */
 759         options.system_hostfile =
 760             tilde_expand_filename(options.system_hostfile, original_real_uid);
 761         options.user_hostfile =
 762             tilde_expand_filename(options.user_hostfile, original_real_uid);
 763         options.system_hostfile2 =
 764             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 765         options.user_hostfile2 =
 766             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 767
 768         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 769
 770         /* Log into the remote system.  This never returns if the login fails. */
 771         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 772
 773         /* We no longer need the private host keys.  Clear them now. */
 774         if (sensitive_data.nkeys != 0) {
 775                 for (i = 0; i < sensitive_data.nkeys; i++) {
 776                         if (sensitive_data.keys[i] != NULL) {
 777                                 /* Destroys contents safely */
 778                                 debug3("clear hostkey %d", i);
 779                                 key_free(sensitive_data.keys[i]);
 780                                 sensitive_data.keys[i] = NULL;
 781                         }
 782                 }
 783                 xfree(sensitive_data.keys);
 784         }
 785         for (i = 0; i < options.num_identity_files; i++) {
 786                 if (options.identity_files[i]) {
 787                         xfree(options.identity_files[i]);
 788                         options.identity_files[i] = NULL;
 789                 }
 790                 if (options.identity_keys[i]) {
 791                         key_free(options.identity_keys[i]);
 792                         options.identity_keys[i] = NULL;
 793                 }
 794         }
 795
 796         exit_status = compat20 ? ssh_session2() : ssh_session();
 797         packet_close();
 798
 799         if (options.control_path != NULL && control_fd != -1)
 800                 unlink(options.control_path);
 801
 802         /*
 803          * Send SIGHUP to proxy command if used. We don't wait() in
 804          * case it hangs and instead rely on init to reap the child
 805          */
 806         if (proxy_command_pid > 1)
 807                 kill(proxy_command_pid, SIGHUP);
 808
 809         return exit_status;
 810 }
 811
 812 static void
 813 ssh_init_forwarding(void)
 814 {
 815         int success = 0;
 816         int i;
 817
 818         /* Initiate local TCP/IP port forwardings. */
 819         for (i = 0; i < options.num_local_forwards; i++) {
 820                 debug("Local connections to %.200s:%d forwarded to remote "
 821                     "address %.200s:%d",
 822                     (options.local_forwards[i].listen_host == NULL) ?
 823                     (options.gateway_ports ? "*" : "LOCALHOST") :
 824                     options.local_forwards[i].listen_host,
 825                     options.local_forwards[i].listen_port,
 826                     options.local_forwards[i].connect_host,
 827                     options.local_forwards[i].connect_port);
 828                 success += channel_setup_local_fwd_listener(
 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                     options.gateway_ports, options.hpn_disabled,
 834                     options.hpn_buffer_size);
 835         }
 836         if (i > 0 && success == 0)
 837                 error("Could not request local forwarding.");
 838
 839         /* Initiate remote TCP/IP port forwardings. */
 840         for (i = 0; i < options.num_remote_forwards; i++) {
 841                 debug("Remote connections from %.200s:%d forwarded to "
 842                     "local address %.200s:%d",
 843                     (options.remote_forwards[i].listen_host == NULL) ?
 844                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 845                     options.remote_forwards[i].listen_port,
 846                     options.remote_forwards[i].connect_host,
 847                     options.remote_forwards[i].connect_port);
 848                 channel_request_remote_forwarding(
 849                     options.remote_forwards[i].listen_host,
 850                     options.remote_forwards[i].listen_port,
 851                     options.remote_forwards[i].connect_host,
 852                     options.remote_forwards[i].connect_port);
 853         }
 854 }
 855
 856 static void
 857 check_agent_present(void)
 858 {
 859         if (options.forward_agent) {
 860                 /* Clear agent forwarding if we don't have an agent. */
 861                 if (!ssh_agent_present())
 862                         options.forward_agent = 0;
 863         }
 864 }
 865
 866 static int
 867 ssh_session(void)
 868 {
 869         int type;
 870         int interactive = 0;
 871         int have_tty = 0;
 872         struct winsize ws;
 873         char *cp;
 874         const char *display;
 875
 876         /* Enable compression if requested. */
 877         if (options.compression) {
 878                 debug("Requesting compression at level %d.", options.compression_level);
 879
 880                 if (options.compression_level < 1 || options.compression_level > 9)
 881                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 882
 883                 /* Send the request. */
 884                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 885                 packet_put_int(options.compression_level);
 886                 packet_send();
 887                 packet_write_wait();
 888                 type = packet_read();
 889                 if (type == SSH_SMSG_SUCCESS)
 890                         packet_start_compression(options.compression_level);
 891                 else if (type == SSH_SMSG_FAILURE)
 892                         logit("Warning: Remote host refused compression.");
 893                 else
 894                         packet_disconnect("Protocol error waiting for compression response.");
 895         }
 896         /* Allocate a pseudo tty if appropriate. */
 897         if (tty_flag) {
 898                 debug("Requesting pty.");
 899
 900                 /* Start the packet. */
 901                 packet_start(SSH_CMSG_REQUEST_PTY);
 902
 903                 /* Store TERM in the packet.  There is no limit on the
 904                    length of the string. */
 905                 cp = getenv("TERM");
 906                 if (!cp)
 907                         cp = "";
 908                 packet_put_cstring(cp);
 909
 910                 /* Store window size in the packet. */
 911                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 912                         memset(&ws, 0, sizeof(ws));
 913                 packet_put_int(ws.ws_row);
 914                 packet_put_int(ws.ws_col);
 915                 packet_put_int(ws.ws_xpixel);
 916                 packet_put_int(ws.ws_ypixel);
 917
 918                 /* Store tty modes in the packet. */
 919                 tty_make_modes(fileno(stdin), NULL);
 920
 921                 /* Send the packet, and wait for it to leave. */
 922                 packet_send();
 923                 packet_write_wait();
 924
 925                 /* Read response from the server. */
 926                 type = packet_read();
 927                 if (type == SSH_SMSG_SUCCESS) {
 928                         interactive = 1;
 929                         have_tty = 1;
 930                 } else if (type == SSH_SMSG_FAILURE)
 931                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 932                 else
 933                         packet_disconnect("Protocol error waiting for pty request response.");
 934         }
 935         /* Request X11 forwarding if enabled and DISPLAY is set. */
 936         display = getenv("DISPLAY");
 937         if (options.forward_x11 && display != NULL) {
 938                 char *proto, *data;
 939                 /* Get reasonable local authentication information. */
 940                 client_x11_get_proto(display, options.xauth_location,
 941                     options.forward_x11_trusted, &proto, &data);
 942                 /* Request forwarding with authentication spoofing. */
 943                 debug("Requesting X11 forwarding with authentication spoofing.");
 944                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 945
 946                 /* Read response from the server. */
 947                 type = packet_read();
 948                 if (type == SSH_SMSG_SUCCESS) {
 949                         interactive = 1;
 950                 } else if (type == SSH_SMSG_FAILURE) {
 951                         logit("Warning: Remote host denied X11 forwarding.");
 952                 } else {
 953                         packet_disconnect("Protocol error waiting for X11 forwarding");
 954                 }
 955         }
 956         /* Tell the packet module whether this is an interactive session. */
 957         packet_set_interactive(interactive);
 958
 959         /* Request authentication agent forwarding if appropriate. */
 960         check_agent_present();
 961
 962         if (options.forward_agent) {
 963                 debug("Requesting authentication agent forwarding.");
 964                 auth_request_forwarding();
 965
 966                 /* Read response from the server. */
 967                 type = packet_read();
 968                 packet_check_eom();
 969                 if (type != SSH_SMSG_SUCCESS)
 970                         logit("Warning: Remote host denied authentication agent forwarding.");
 971         }
 972
 973         /* Initiate port forwardings. */
 974         ssh_init_forwarding();
 975
 976         /* If requested, let ssh continue in the background. */
 977         if (fork_after_authentication_flag)
 978                 if (daemon(1, 1) < 0)
 979                         fatal("daemon() failed: %.200s", strerror(errno));
 980
 981         /*
 982          * If a command was specified on the command line, execute the
 983          * command now. Otherwise request the server to start a shell.
 984          */
 985         if (buffer_len(&command) > 0) {
 986                 int len = buffer_len(&command);
 987                 if (len > 900)
 988                         len = 900;
 989                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 990                 packet_start(SSH_CMSG_EXEC_CMD);
 991                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 992                 packet_send();
 993                 packet_write_wait();
 994         } else {
 995                 debug("Requesting shell.");
 996                 packet_start(SSH_CMSG_EXEC_SHELL);
 997                 packet_send();
 998                 packet_write_wait();
 999         }
1000
1001         /* Enter the interactive session. */
1002         return client_loop(have_tty, tty_flag ?
1003             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1004 }
1005
1006 static void
1007 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1008 {
1009         int id, len;
1010
1011         id = packet_get_int();
1012         len = buffer_len(&command);
1013         if (len > 900)
1014                 len = 900;
1015         packet_check_eom();
1016         if (type == SSH2_MSG_CHANNEL_FAILURE)
1017                 fatal("Request for subsystem '%.*s' failed on channel %d",
1018                     len, (u_char *)buffer_ptr(&command), id);
1019 }
1020
1021 void
1022 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1023 {
1024         int i;
1025
1026         i = client_global_request_id++;
1027         if (i >= options.num_remote_forwards)
1028                 return;
1029         debug("remote forward %s for: listen %d, connect %s:%d",
1030             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1031             options.remote_forwards[i].listen_port,
1032             options.remote_forwards[i].connect_host,
1033             options.remote_forwards[i].connect_port);
1034         if (type == SSH2_MSG_REQUEST_FAILURE)
1035                 logit("Warning: remote port forwarding failed for listen "
1036                     "port %d", options.remote_forwards[i].listen_port);
1037 }
1038
1039 static void
1040 ssh_control_listener(void)
1041 {
1042         struct sockaddr_un addr;
1043         mode_t old_umask;
1044         int addr_len;
1045
1046         if (options.control_path == NULL ||
1047             options.control_master == SSHCTL_MASTER_NO)
1048                 return;
1049
1050         debug("setting up multiplex master socket");
1051
1052         memset(&addr, '\0', sizeof(addr));
1053         addr.sun_family = AF_UNIX;
1054         addr_len = offsetof(struct sockaddr_un, sun_path) +
1055             strlen(options.control_path) + 1;
1056
1057         if (strlcpy(addr.sun_path, options.control_path,
1058             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1059                 fatal("ControlPath too long");
1060
1061         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1062                 fatal("%s socket(): %s", __func__, strerror(errno));
1063
1064         old_umask = umask(0177);
1065         if (bind(control_fd, (struct sockaddr*)&addr, addr_len) == -1) {
1066                 control_fd = -1;
1067                 if (errno == EINVAL || errno == EADDRINUSE)
1068                         fatal("ControlSocket %s already exists",
1069                             options.control_path);
1070                 else
1071                         fatal("%s bind(): %s", __func__, strerror(errno));
1072         }
1073         umask(old_umask);
1074
1075         if (listen(control_fd, 64) == -1)
1076                 fatal("%s listen(): %s", __func__, strerror(errno));
1077
1078         set_nonblock(control_fd);
1079 }
1080
1081 /* request pty/x11/agent/tcpfwd/shell for channel */
1082 static void
1083 ssh_session2_setup(int id, void *arg)
1084 {
1085         extern char **environ;
1086         const char *display;
1087         int interactive = tty_flag;
1088
1089         display = getenv("DISPLAY");
1090         if (options.forward_x11 && display != NULL) {
1091                 char *proto, *data;
1092                 /* Get reasonable local authentication information. */
1093                 client_x11_get_proto(display, options.xauth_location,
1094                     options.forward_x11_trusted, &proto, &data);
1095                 /* Request forwarding with authentication spoofing. */
1096                 debug("Requesting X11 forwarding with authentication spoofing.");
1097                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1098                 interactive = 1;
1099                 /* XXX wait for reply */
1100         }
1101
1102         check_agent_present();
1103         if (options.forward_agent) {
1104                 debug("Requesting authentication agent forwarding.");
1105                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1106                 packet_send();
1107         }
1108
1109         if (options.tun_open != SSH_TUNMODE_NO) {
1110                 Channel *c;
1111                 int fd;
1112
1113                 debug("Requesting tun.");
1114                 if ((fd = tun_open(options.tun_local,
1115                     options.tun_open)) >= 0) {
1116                         if(options.hpn_disabled)
1117                                 c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1118                                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1119                                     0, "tun", 1);
1120                         else
1121                                 c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1122                                     options.hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT,
1123                                     0, "tun", 1);
1124                         c->datagram = 1;
1125 #if defined(SSH_TUN_FILTER)
1126                         if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
1127                                 channel_register_filter(c->self, sys_tun_infilter,
1128                                     sys_tun_outfilter);
1129 #endif
1130                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1131                         packet_put_cstring("tun@openssh.com");
1132                         packet_put_int(c->self);
1133                         packet_put_int(c->local_window_max);
1134                         packet_put_int(c->local_maxpacket);
1135                         packet_put_int(options.tun_open);
1136                         packet_put_int(options.tun_remote);
1137                         packet_send();
1138                 }
1139         }
1140
1141         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1142             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1143
1144         packet_set_interactive(interactive);
1145 }
1146
1147 /* open new channel for a session */
1148 static int
1149 ssh_session2_open(void)
1150 {
1151         Channel *c;
1152         int window, packetmax, in, out, err;
1153
1154         if (stdin_null_flag) {
1155                 in = open(_PATH_DEVNULL, O_RDONLY);
1156         } else {
1157                 in = dup(STDIN_FILENO);
1158         }
1159         out = dup(STDOUT_FILENO);
1160         err = dup(STDERR_FILENO);
1161
1162         if (in < 0 || out < 0 || err < 0)
1163                 fatal("dup() in/out/err failed");
1164
1165         /* enable nonblocking unless tty */
1166         if (!isatty(in))
1167                 set_nonblock(in);
1168         if (!isatty(out))
1169                 set_nonblock(out);
1170         if (!isatty(err))
1171                 set_nonblock(err);
1172
1173         if(options.hpn_disabled)
1174                 window = CHAN_SES_WINDOW_DEFAULT;
1175         else
1176                 window = options.hpn_buffer_size;
1177         packetmax = CHAN_SES_PACKET_DEFAULT;
1178         if (tty_flag) {
1179                 window = 4*CHAN_SES_PACKET_DEFAULT;
1180                 window >>= 1;
1181                 packetmax >>= 1;
1182         }
1183         c = channel_new(
1184             "session", SSH_CHANNEL_OPENING, in, out, err,
1185             window, packetmax, CHAN_EXTENDED_WRITE,
1186             "client-session", /*nonblock*/0);
1187         if ((options.tcp_rcv_buf_poll > 0) && (!options.hpn_disabled)) {
1188                 c->dynamic_window = 1;
1189                 debug ("Enabled Dynamic Window Scaling\n");
1190         }
1191         debug3("ssh_session2_open: channel_new: %d", c->self);
1192
1193         channel_send_open(c->self);
1194         if (!no_shell_flag)
1195                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1196
1197         return c->self;
1198 }
1199
1200 static int
1201 ssh_session2(void)
1202 {
1203         int id = -1;
1204
1205         /* XXX should be pre-session */
1206         ssh_init_forwarding();
1207         ssh_control_listener();
1208
1209         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1210                 id = ssh_session2_open();
1211
1212         /* Execute a local command */
1213         if (options.local_command != NULL &&
1214             options.permit_local_command)
1215                 ssh_local_cmd(options.local_command);
1216
1217         /* If requested, let ssh continue in the background. */
1218         if (fork_after_authentication_flag)
1219                 if (daemon(1, 1) < 0)
1220                         fatal("daemon() failed: %.200s", strerror(errno));
1221
1222         return client_loop(tty_flag, tty_flag ?
1223             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1224 }
1225
1226 static void
1227 load_public_identity_files(void)
1228 {
1229         char *filename;
1230         int i = 0;
1231         Key *public;
1232 #ifdef SMARTCARD
1233         Key **keys;
1234
1235         if (options.smartcard_device != NULL &&
1236             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1237             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1238                 int count = 0;
1239                 for (i = 0; keys[i] != NULL; i++) {
1240                         count++;
1241                         memmove(&options.identity_files[1], &options.identity_files[0],
1242                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1243                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1244                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1245                         options.num_identity_files++;
1246                         options.identity_keys[0] = keys[i];
1247                         options.identity_files[0] = sc_get_key_label(keys[i]);
1248                 }
1249                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1250                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1251                 i = count;
1252                 xfree(keys);
1253         }
1254 #endif /* SMARTCARD */
1255         for (; i < options.num_identity_files; i++) {
1256                 filename = tilde_expand_filename(options.identity_files[i],
1257                     original_real_uid);
1258                 public = key_load_public(filename, NULL);
1259                 debug("identity file %s type %d", filename,
1260                     public ? public->type : -1);
1261                 xfree(options.identity_files[i]);
1262                 options.identity_files[i] = filename;
1263                 options.identity_keys[i] = public;
1264         }
1265 }
1266
1267 static void
1268 control_client_sighandler(int signo)
1269 {
1270         control_client_terminate = signo;
1271 }
1272
1273 static void
1274 control_client_sigrelay(int signo)
1275 {
1276         if (control_server_pid > 1)
1277                 kill(control_server_pid, signo);
1278 }
1279
1280 static int
1281 env_permitted(char *env)
1282 {
1283         int i;
1284         char name[1024], *cp;
1285
1286         strlcpy(name, env, sizeof(name));
1287         if ((cp = strchr(name, '=')) == NULL)
1288                 return (0);
1289
1290         *cp = '\0';
1291
1292         for (i = 0; i < options.num_send_env; i++)
1293                 if (match_pattern(name, options.send_env[i]))
1294                         return (1);
1295
1296         return (0);
1297 }
1298
1299 static void
1300 control_client(const char *path)
1301 {
1302         struct sockaddr_un addr;
1303         int i, r, fd, sock, exitval, num_env, addr_len;
1304         Buffer m;
1305         char *term;
1306         extern char **environ;
1307         u_int  flags;
1308
1309         if (mux_command == 0)
1310                 mux_command = SSHMUX_COMMAND_OPEN;
1311
1312         switch (options.control_master) {
1313         case SSHCTL_MASTER_AUTO:
1314         case SSHCTL_MASTER_AUTO_ASK:
1315                 debug("auto-mux: Trying existing master");
1316                 /* FALLTHROUGH */
1317         case SSHCTL_MASTER_NO:
1318                 break;
1319         default:
1320                 return;
1321         }
1322
1323         memset(&addr, '\0', sizeof(addr));
1324         addr.sun_family = AF_UNIX;
1325         addr_len = offsetof(struct sockaddr_un, sun_path) +
1326             strlen(path) + 1;
1327
1328         if (strlcpy(addr.sun_path, path,
1329             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1330                 fatal("ControlPath too long");
1331
1332         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1333                 fatal("%s socket(): %s", __func__, strerror(errno));
1334
1335         if (connect(sock, (struct sockaddr*)&addr, addr_len) == -1) {
1336                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1337                         fatal("Control socket connect(%.100s): %s", path,
1338                             strerror(errno));
1339                 }
1340                 if (errno == ENOENT)
1341                         debug("Control socket \"%.100s\" does not exist", path);
1342                 else {
1343                         error("Control socket connect(%.100s): %s", path,
1344                             strerror(errno));
1345                 }
1346                 close(sock);
1347                 return;
1348         }
1349
1350         if (stdin_null_flag) {
1351                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1352                         fatal("open(/dev/null): %s", strerror(errno));
1353                 if (dup2(fd, STDIN_FILENO) == -1)
1354                         fatal("dup2: %s", strerror(errno));
1355                 if (fd > STDERR_FILENO)
1356                         close(fd);
1357         }
1358
1359         term = getenv("TERM");
1360
1361         flags = 0;
1362         if (tty_flag)
1363                 flags |= SSHMUX_FLAG_TTY;
1364         if (subsystem_flag)
1365                 flags |= SSHMUX_FLAG_SUBSYS;
1366         if (options.forward_x11)
1367                 flags |= SSHMUX_FLAG_X11_FWD;
1368         if (options.forward_agent)
1369                 flags |= SSHMUX_FLAG_AGENT_FWD;
1370         if (options.num_local_forwards > 0)
1371                 flags |= SSHMUX_FLAG_PORTFORWARD;
1372         buffer_init(&m);
1373
1374         /* Send our command to server */
1375         buffer_put_int(&m, mux_command);
1376         buffer_put_int(&m, flags);
1377         if (options.num_local_forwards > 0)
1378         {
1379                 if (options.local_forwards[0].listen_host == NULL)
1380                         buffer_put_string(&m,"LOCALHOST",11);
1381                 else
1382                         buffer_put_string(&m,options.local_forwards[0].listen_host,512);
1383                 buffer_put_int(&m,options.local_forwards[0].listen_port);
1384                 buffer_put_string(&m,options.local_forwards[0].connect_host,512);
1385                 buffer_put_int(&m,options.local_forwards[0].connect_port);
1386         }
1387         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1388                 fatal("%s: msg_send", __func__);
1389         buffer_clear(&m);
1390
1391         /* Get authorisation status and PID of controlee */
1392         if (ssh_msg_recv(sock, &m) == -1)
1393                 fatal("%s: msg_recv", __func__);
1394         if (buffer_get_char(&m) != SSHMUX_VER)
1395                 fatal("%s: wrong version", __func__);
1396         if (buffer_get_int(&m) != 1)
1397                 fatal("Connection to master denied");
1398         control_server_pid = buffer_get_int(&m);
1399
1400         buffer_clear(&m);
1401
1402         switch (mux_command) {
1403         case SSHMUX_COMMAND_ALIVE_CHECK:
1404                 fprintf(stderr, "Master running (pid=%d)\r\n",
1405                     control_server_pid);
1406                 exit(0);
1407         case SSHMUX_COMMAND_TERMINATE:
1408                 fprintf(stderr, "Exit request sent.\r\n");
1409                 exit(0);
1410         case SSHMUX_COMMAND_OPEN:
1411                 /* continue below */
1412                 break;
1413         default:
1414                 fatal("silly mux_command %d", mux_command);
1415         }
1416
1417         /* SSHMUX_COMMAND_OPEN */
1418         buffer_put_cstring(&m, term ? term : "");
1419         buffer_append(&command, "\0", 1);
1420         buffer_put_cstring(&m, buffer_ptr(&command));
1421
1422         if (options.num_send_env == 0 || environ == NULL) {
1423                 buffer_put_int(&m, 0);
1424         } else {
1425                 /* Pass environment */
1426                 num_env = 0;
1427                 for (i = 0; environ[i] != NULL; i++)
1428                         if (env_permitted(environ[i]))
1429                                 num_env++; /* Count */
1430
1431                 buffer_put_int(&m, num_env);
1432
1433                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1434                         if (env_permitted(environ[i])) {
1435                                 num_env--;
1436                                 buffer_put_cstring(&m, environ[i]);
1437                         }
1438         }
1439
1440         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1441                 fatal("%s: msg_send", __func__);
1442
1443         mm_send_fd(sock, STDIN_FILENO);
1444         mm_send_fd(sock, STDOUT_FILENO);
1445         mm_send_fd(sock, STDERR_FILENO);
1446
1447         /* Wait for reply, so master has a chance to gather ttymodes */
1448         buffer_clear(&m);
1449         if (ssh_msg_recv(sock, &m) == -1)
1450                 fatal("%s: msg_recv", __func__);
1451         if (buffer_get_char(&m) != SSHMUX_VER)
1452                 fatal("%s: wrong version", __func__);
1453         buffer_free(&m);
1454
1455         signal(SIGHUP, control_client_sighandler);
1456         signal(SIGINT, control_client_sighandler);
1457         signal(SIGTERM, control_client_sighandler);
1458         signal(SIGWINCH, control_client_sigrelay);
1459
1460         if (tty_flag)
1461                 enter_raw_mode();
1462
1463         /* Stick around until the controlee closes the client_fd */
1464         exitval = 0;
1465         for (;!control_client_terminate;) {
1466                 r = read(sock, &exitval, sizeof(exitval));
1467                 if (r == 0) {
1468                         debug2("Received EOF from master");
1469                         break;
1470                 }
1471                 if (r > 0)
1472                         debug2("Received exit status from master %d", exitval);
1473                 if (r == -1 && errno != EINTR)
1474                         fatal("%s: read %s", __func__, strerror(errno));
1475         }
1476
1477         if (control_client_terminate)
1478                 debug2("Exiting on signal %d", control_client_terminate);
1479
1480         close(sock);
1481
1482         leave_raw_mode();
1483
1484         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1485                 fprintf(stderr, "Connection to master closed.\r\n");
1486
1487         exit(exitval);
1488 }