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 1.250 2005/09/13 23:40:07 djm Exp $");
  44
  45 #include <openssl/evp.h>
  46 #include <openssl/err.h>
  47
  48 #include "ssh.h"
  49 #include "ssh1.h"
  50 #include "ssh2.h"
  51 #include "compat.h"
  52 #include "cipher.h"
  53 #include "xmalloc.h"
  54 #include "packet.h"
  55 #include "buffer.h"
  56 #include "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 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 "           [user@]hostname [command]\n"
 166         );
 167         exit(1);
 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(1);
 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:TVXY")) != -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 'q':
 344                         options.log_level = SYSLOG_LEVEL_QUIET;
 345                         break;
 346                 case 'e':
 347                         if (optarg[0] == '^' && optarg[2] == 0 &&
 348                             (u_char) optarg[1] >= 64 &&
 349                             (u_char) optarg[1] < 128)
 350                                 options.escape_char = (u_char) optarg[1] & 31;
 351                         else if (strlen(optarg) == 1)
 352                                 options.escape_char = (u_char) optarg[0];
 353                         else if (strcmp(optarg, "none") == 0)
 354                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 355                         else {
 356                                 fprintf(stderr, "Bad escape character '%s'.\n",
 357                                     optarg);
 358                                 exit(1);
 359                         }
 360                         break;
 361                 case 'c':
 362                         if (ciphers_valid(optarg)) {
 363                                 /* SSH2 only */
 364                                 options.ciphers = xstrdup(optarg);
 365                                 options.cipher = SSH_CIPHER_INVALID;
 366                         } else {
 367                                 /* SSH1 only */
 368                                 options.cipher = cipher_number(optarg);
 369                                 if (options.cipher == -1) {
 370                                         fprintf(stderr,
 371                                             "Unknown cipher type '%s'\n",
 372                                             optarg);
 373                                         exit(1);
 374                                 }
 375                                 if (options.cipher == SSH_CIPHER_3DES)
 376                                         options.ciphers = "3des-cbc";
 377                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 378                                         options.ciphers = "blowfish-cbc";
 379                                 else
 380                                         options.ciphers = (char *)-1;
 381                         }
 382                         break;
 383                 case 'm':
 384                         if (mac_valid(optarg))
 385                                 options.macs = xstrdup(optarg);
 386                         else {
 387                                 fprintf(stderr, "Unknown mac type '%s'\n",
 388                                     optarg);
 389                                 exit(1);
 390                         }
 391                         break;
 392                 case 'M':
 393                         if (options.control_master == SSHCTL_MASTER_YES)
 394                                 options.control_master = SSHCTL_MASTER_ASK;
 395                         else
 396                                 options.control_master = SSHCTL_MASTER_YES;
 397                         break;
 398                 case 'p':
 399                         options.port = a2port(optarg);
 400                         if (options.port == 0) {
 401                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 402                                 exit(1);
 403                         }
 404                         break;
 405                 case 'l':
 406                         options.user = optarg;
 407                         break;
 408
 409                 case 'L':
 410                         if (parse_forward(&fwd, optarg))
 411                                 add_local_forward(&options, &fwd);
 412                         else {
 413                                 fprintf(stderr,
 414                                     "Bad local forwarding specification '%s'\n",
 415                                     optarg);
 416                                 exit(1);
 417                         }
 418                         break;
 419
 420                 case 'R':
 421                         if (parse_forward(&fwd, optarg)) {
 422                                 add_remote_forward(&options, &fwd);
 423                         } else {
 424                                 fprintf(stderr,
 425                                     "Bad remote forwarding specification "
 426                                     "'%s'\n", optarg);
 427                                 exit(1);
 428                         }
 429                         break;
 430
 431                 case 'D':
 432                         cp = p = xstrdup(optarg);
 433                         memset(&fwd, '\0', sizeof(fwd));
 434                         fwd.connect_host = "socks";
 435                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 436                                 fprintf(stderr, "Bad dynamic forwarding "
 437                                     "specification '%.100s'\n", optarg);
 438                                 exit(1);
 439                         }
 440                         if (cp != NULL) {
 441                                 fwd.listen_port = a2port(cp);
 442                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 443                         } else {
 444                                 fwd.listen_port = a2port(fwd.listen_host);
 445                                 fwd.listen_host = NULL;
 446                         }
 447
 448                         if (fwd.listen_port == 0) {
 449                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 450                                     optarg);
 451                                 exit(1);
 452                         }
 453                         add_local_forward(&options, &fwd);
 454                         xfree(p);
 455                         break;
 456
 457                 case 'C':
 458                         options.compression = 1;
 459                         break;
 460                 case 'N':
 461                         no_shell_flag = 1;
 462                         no_tty_flag = 1;
 463                         break;
 464                 case 'T':
 465                         no_tty_flag = 1;
 466                         break;
 467                 case 'o':
 468                         dummy = 1;
 469                         line = xstrdup(optarg);
 470                         if (process_config_line(&options, host ? host : "",
 471                             line, "command-line", 0, &dummy) != 0)
 472                                 exit(1);
 473                         xfree(line);
 474                         break;
 475                 case 's':
 476                         subsystem_flag = 1;
 477                         break;
 478                 case 'S':
 479                         if (options.control_path != NULL)
 480                                 free(options.control_path);
 481                         options.control_path = xstrdup(optarg);
 482                         break;
 483                 case 'b':
 484                         options.bind_address = optarg;
 485                         break;
 486                 case 'F':
 487                         config = optarg;
 488                         break;
 489                 default:
 490                         usage();
 491                 }
 492         }
 493
 494         ac -= optind;
 495         av += optind;
 496
 497         if (ac > 0 && !host && **av != '-') {
 498                 if (strrchr(*av, '@')) {
 499                         p = xstrdup(*av);
 500                         cp = strrchr(p, '@');
 501                         if (cp == NULL || cp == p)
 502                                 usage();
 503                         options.user = p;
 504                         *cp = '\0';
 505                         host = ++cp;
 506                 } else
 507                         host = *av;
 508                 if (ac > 1) {
 509                         optind = optreset = 1;
 510                         goto again;
 511                 }
 512                 ac--, av++;
 513         }
 514
 515         /* Check that we got a host name. */
 516         if (!host)
 517                 usage();
 518
 519         SSLeay_add_all_algorithms();
 520         ERR_load_crypto_strings();
 521
 522         /* Initialize the command to execute on remote host. */
 523         buffer_init(&command);
 524
 525         /*
 526          * Save the command to execute on the remote host in a buffer. There
 527          * is no limit on the length of the command, except by the maximum
 528          * packet size.  Also sets the tty flag if there is no command.
 529          */
 530         if (!ac) {
 531                 /* No command specified - execute shell on a tty. */
 532                 tty_flag = 1;
 533                 if (subsystem_flag) {
 534                         fprintf(stderr,
 535                             "You must specify a subsystem to invoke.\n");
 536                         usage();
 537                 }
 538         } else {
 539                 /* A command has been specified.  Store it into the buffer. */
 540                 for (i = 0; i < ac; i++) {
 541                         if (i)
 542                                 buffer_append(&command, " ", 1);
 543                         buffer_append(&command, av[i], strlen(av[i]));
 544                 }
 545         }
 546
 547         /* Cannot fork to background if no command. */
 548         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 549                 fatal("Cannot fork into background without a command to execute.");
 550
 551         /* Allocate a tty by default if no command specified. */
 552         if (buffer_len(&command) == 0)
 553                 tty_flag = 1;
 554
 555         /* Force no tty */
 556         if (no_tty_flag)
 557                 tty_flag = 0;
 558         /* Do not allocate a tty if stdin is not a tty. */
 559         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 560                 if (tty_flag)
 561                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 562                 tty_flag = 0;
 563         }
 564
 565         /*
 566          * Initialize "log" output.  Since we are the client all output
 567          * actually goes to stderr.
 568          */
 569         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 570             SYSLOG_FACILITY_USER, 1);
 571
 572         /*
 573          * Read per-user configuration file.  Ignore the system wide config
 574          * file if the user specifies a config file on the command line.
 575          */
 576         if (config != NULL) {
 577                 if (!read_config_file(config, host, &options, 0))
 578                         fatal("Can't open user config file %.100s: "
 579                             "%.100s", config, strerror(errno));
 580         } else  {
 581                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 582                     _PATH_SSH_USER_CONFFILE);
 583                 (void)read_config_file(buf, host, &options, 1);
 584
 585                 /* Read systemwide configuration file after use config. */
 586                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 587                     &options, 0);
 588         }
 589
 590         /* Fill configuration defaults. */
 591         fill_default_options(&options);
 592
 593         channel_set_af(options.address_family);
 594
 595         /* reinit */
 596         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 597
 598         seed_rng();
 599
 600         if (options.user == NULL)
 601                 options.user = xstrdup(pw->pw_name);
 602
 603         if (options.hostname != NULL)
 604                 host = options.hostname;
 605
 606         /* force lowercase for hostkey matching */
 607         if (options.host_key_alias != NULL) {
 608                 for (p = options.host_key_alias; *p; p++)
 609                         if (isupper(*p))
 610                                 *p = tolower(*p);
 611         }
 612
 613         /* Get default port if port has not been set. */
 614         if (options.port == 0) {
 615                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 616                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 617         }
 618
 619         if (options.proxy_command != NULL &&
 620             strcmp(options.proxy_command, "none") == 0)
 621                 options.proxy_command = NULL;
 622         if (options.control_path != NULL &&
 623             strcmp(options.control_path, "none") == 0)
 624                 options.control_path = NULL;
 625
 626         if (options.control_path != NULL) {
 627                 snprintf(buf, sizeof(buf), "%d", options.port);
 628                 cp = tilde_expand_filename(options.control_path,
 629                     original_real_uid);
 630                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 631                     "r", options.user, (char *)NULL);
 632                 xfree(cp);
 633         }
 634         if (mux_command != 0 && options.control_path == NULL)
 635                 fatal("No ControlPath specified for \"-O\" command");
 636         if (options.control_path != NULL)
 637                 control_client(options.control_path);
 638
 639         /* Open a connection to the remote host. */
 640         if (ssh_connect(host, &hostaddr, options.port,
 641             options.address_family, options.connection_attempts,
 642 #ifdef HAVE_CYGWIN
 643             options.use_privileged_port,
 644 #else
 645             original_effective_uid == 0 && options.use_privileged_port,
 646 #endif
 647             options.proxy_command) != 0)
 648                 exit(1);
 649
 650         /*
 651          * If we successfully made the connection, load the host private key
 652          * in case we will need it later for combined rsa-rhosts
 653          * authentication. This must be done before releasing extra
 654          * privileges, because the file is only readable by root.
 655          * If we cannot access the private keys, load the public keys
 656          * instead and try to execute the ssh-keysign helper instead.
 657          */
 658         sensitive_data.nkeys = 0;
 659         sensitive_data.keys = NULL;
 660         sensitive_data.external_keysign = 0;
 661         if (options.rhosts_rsa_authentication ||
 662             options.hostbased_authentication) {
 663                 sensitive_data.nkeys = 3;
 664                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 665                     sizeof(Key));
 666
 667                 PRIV_START;
 668                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 669                     _PATH_HOST_KEY_FILE, "", NULL);
 670                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 671                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 672                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 673                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 674                 PRIV_END;
 675
 676                 if (options.hostbased_authentication == 1 &&
 677                     sensitive_data.keys[0] == NULL &&
 678                     sensitive_data.keys[1] == NULL &&
 679                     sensitive_data.keys[2] == NULL) {
 680                         sensitive_data.keys[1] = key_load_public(
 681                             _PATH_HOST_DSA_KEY_FILE, NULL);
 682                         sensitive_data.keys[2] = key_load_public(
 683                             _PATH_HOST_RSA_KEY_FILE, NULL);
 684                         sensitive_data.external_keysign = 1;
 685                 }
 686         }
 687         /*
 688          * Get rid of any extra privileges that we may have.  We will no
 689          * longer need them.  Also, extra privileges could make it very hard
 690          * to read identity files and other non-world-readable files from the
 691          * user's home directory if it happens to be on a NFS volume where
 692          * root is mapped to nobody.
 693          */
 694         if (original_effective_uid == 0) {
 695                 PRIV_START;
 696                 permanently_set_uid(pw);
 697         }
 698
 699         /*
 700          * Now that we are back to our own permissions, create ~/.ssh
 701          * directory if it doesn\'t already exist.
 702          */
 703         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 704         if (stat(buf, &st) < 0)
 705                 if (mkdir(buf, 0700) < 0)
 706                         error("Could not create directory '%.200s'.", buf);
 707
 708         /* load options.identity_files */
 709         load_public_identity_files();
 710
 711         /* Expand ~ in known host file names. */
 712         /* XXX mem-leaks: */
 713         options.system_hostfile =
 714             tilde_expand_filename(options.system_hostfile, original_real_uid);
 715         options.user_hostfile =
 716             tilde_expand_filename(options.user_hostfile, original_real_uid);
 717         options.system_hostfile2 =
 718             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 719         options.user_hostfile2 =
 720             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 721
 722         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 723
 724         /* Log into the remote system.  This never returns if the login fails. */
 725         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 726
 727         /* We no longer need the private host keys.  Clear them now. */
 728         if (sensitive_data.nkeys != 0) {
 729                 for (i = 0; i < sensitive_data.nkeys; i++) {
 730                         if (sensitive_data.keys[i] != NULL) {
 731                                 /* Destroys contents safely */
 732                                 debug3("clear hostkey %d", i);
 733                                 key_free(sensitive_data.keys[i]);
 734                                 sensitive_data.keys[i] = NULL;
 735                         }
 736                 }
 737                 xfree(sensitive_data.keys);
 738         }
 739         for (i = 0; i < options.num_identity_files; i++) {
 740                 if (options.identity_files[i]) {
 741                         xfree(options.identity_files[i]);
 742                         options.identity_files[i] = NULL;
 743                 }
 744                 if (options.identity_keys[i]) {
 745                         key_free(options.identity_keys[i]);
 746                         options.identity_keys[i] = NULL;
 747                 }
 748         }
 749
 750         exit_status = compat20 ? ssh_session2() : ssh_session();
 751         packet_close();
 752
 753         if (options.control_path != NULL && control_fd != -1)
 754                 unlink(options.control_path);
 755
 756         /*
 757          * Send SIGHUP to proxy command if used. We don't wait() in
 758          * case it hangs and instead rely on init to reap the child
 759          */
 760         if (proxy_command_pid > 1)
 761                 kill(proxy_command_pid, SIGHUP);
 762
 763         return exit_status;
 764 }
 765
 766 static void
 767 ssh_init_forwarding(void)
 768 {
 769         int success = 0;
 770         int i;
 771
 772         /* Initiate local TCP/IP port forwardings. */
 773         for (i = 0; i < options.num_local_forwards; i++) {
 774                 debug("Local connections to %.200s:%d forwarded to remote "
 775                     "address %.200s:%d",
 776                     (options.local_forwards[i].listen_host == NULL) ?
 777                     (options.gateway_ports ? "*" : "LOCALHOST") :
 778                     options.local_forwards[i].listen_host,
 779                     options.local_forwards[i].listen_port,
 780                     options.local_forwards[i].connect_host,
 781                     options.local_forwards[i].connect_port);
 782                 success += channel_setup_local_fwd_listener(
 783                     options.local_forwards[i].listen_host,
 784                     options.local_forwards[i].listen_port,
 785                     options.local_forwards[i].connect_host,
 786                     options.local_forwards[i].connect_port,
 787                     options.gateway_ports);
 788         }
 789         if (i > 0 && success == 0)
 790                 error("Could not request local forwarding.");
 791
 792         /* Initiate remote TCP/IP port forwardings. */
 793         for (i = 0; i < options.num_remote_forwards; i++) {
 794                 debug("Remote connections from %.200s:%d forwarded to "
 795                     "local address %.200s:%d",
 796                     (options.remote_forwards[i].listen_host == NULL) ?
 797                     (options.gateway_ports ? "*" : "LOCALHOST") :
 798                     options.remote_forwards[i].listen_host,
 799                     options.remote_forwards[i].listen_port,
 800                     options.remote_forwards[i].connect_host,
 801                     options.remote_forwards[i].connect_port);
 802                 channel_request_remote_forwarding(
 803                     options.remote_forwards[i].listen_host,
 804                     options.remote_forwards[i].listen_port,
 805                     options.remote_forwards[i].connect_host,
 806                     options.remote_forwards[i].connect_port);
 807         }
 808 }
 809
 810 static void
 811 check_agent_present(void)
 812 {
 813         if (options.forward_agent) {
 814                 /* Clear agent forwarding if we don\'t have an agent. */
 815                 if (!ssh_agent_present())
 816                         options.forward_agent = 0;
 817         }
 818 }
 819
 820 static int
 821 ssh_session(void)
 822 {
 823         int type;
 824         int interactive = 0;
 825         int have_tty = 0;
 826         struct winsize ws;
 827         char *cp;
 828         const char *display;
 829
 830         /* Enable compression if requested. */
 831         if (options.compression) {
 832                 debug("Requesting compression at level %d.", options.compression_level);
 833
 834                 if (options.compression_level < 1 || options.compression_level > 9)
 835                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 836
 837                 /* Send the request. */
 838                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 839                 packet_put_int(options.compression_level);
 840                 packet_send();
 841                 packet_write_wait();
 842                 type = packet_read();
 843                 if (type == SSH_SMSG_SUCCESS)
 844                         packet_start_compression(options.compression_level);
 845                 else if (type == SSH_SMSG_FAILURE)
 846                         logit("Warning: Remote host refused compression.");
 847                 else
 848                         packet_disconnect("Protocol error waiting for compression response.");
 849         }
 850         /* Allocate a pseudo tty if appropriate. */
 851         if (tty_flag) {
 852                 debug("Requesting pty.");
 853
 854                 /* Start the packet. */
 855                 packet_start(SSH_CMSG_REQUEST_PTY);
 856
 857                 /* Store TERM in the packet.  There is no limit on the
 858                    length of the string. */
 859                 cp = getenv("TERM");
 860                 if (!cp)
 861                         cp = "";
 862                 packet_put_cstring(cp);
 863
 864                 /* Store window size in the packet. */
 865                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 866                         memset(&ws, 0, sizeof(ws));
 867                 packet_put_int(ws.ws_row);
 868                 packet_put_int(ws.ws_col);
 869                 packet_put_int(ws.ws_xpixel);
 870                 packet_put_int(ws.ws_ypixel);
 871
 872                 /* Store tty modes in the packet. */
 873                 tty_make_modes(fileno(stdin), NULL);
 874
 875                 /* Send the packet, and wait for it to leave. */
 876                 packet_send();
 877                 packet_write_wait();
 878
 879                 /* Read response from the server. */
 880                 type = packet_read();
 881                 if (type == SSH_SMSG_SUCCESS) {
 882                         interactive = 1;
 883                         have_tty = 1;
 884                 } else if (type == SSH_SMSG_FAILURE)
 885                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 886                 else
 887                         packet_disconnect("Protocol error waiting for pty request response.");
 888         }
 889         /* Request X11 forwarding if enabled and DISPLAY is set. */
 890         display = getenv("DISPLAY");
 891         if (options.forward_x11 && display != NULL) {
 892                 char *proto, *data;
 893                 /* Get reasonable local authentication information. */
 894                 client_x11_get_proto(display, options.xauth_location,
 895                     options.forward_x11_trusted, &proto, &data);
 896                 /* Request forwarding with authentication spoofing. */
 897                 debug("Requesting X11 forwarding with authentication spoofing.");
 898                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 899
 900                 /* Read response from the server. */
 901                 type = packet_read();
 902                 if (type == SSH_SMSG_SUCCESS) {
 903                         interactive = 1;
 904                 } else if (type == SSH_SMSG_FAILURE) {
 905                         logit("Warning: Remote host denied X11 forwarding.");
 906                 } else {
 907                         packet_disconnect("Protocol error waiting for X11 forwarding");
 908                 }
 909         }
 910         /* Tell the packet module whether this is an interactive session. */
 911         packet_set_interactive(interactive);
 912
 913         /* Request authentication agent forwarding if appropriate. */
 914         check_agent_present();
 915
 916         if (options.forward_agent) {
 917                 debug("Requesting authentication agent forwarding.");
 918                 auth_request_forwarding();
 919
 920                 /* Read response from the server. */
 921                 type = packet_read();
 922                 packet_check_eom();
 923                 if (type != SSH_SMSG_SUCCESS)
 924                         logit("Warning: Remote host denied authentication agent forwarding.");
 925         }
 926
 927         /* Initiate port forwardings. */
 928         ssh_init_forwarding();
 929
 930         /* If requested, let ssh continue in the background. */
 931         if (fork_after_authentication_flag)
 932                 if (daemon(1, 1) < 0)
 933                         fatal("daemon() failed: %.200s", strerror(errno));
 934
 935         /*
 936          * If a command was specified on the command line, execute the
 937          * command now. Otherwise request the server to start a shell.
 938          */
 939         if (buffer_len(&command) > 0) {
 940                 int len = buffer_len(&command);
 941                 if (len > 900)
 942                         len = 900;
 943                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 944                 packet_start(SSH_CMSG_EXEC_CMD);
 945                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 946                 packet_send();
 947                 packet_write_wait();
 948         } else {
 949                 debug("Requesting shell.");
 950                 packet_start(SSH_CMSG_EXEC_SHELL);
 951                 packet_send();
 952                 packet_write_wait();
 953         }
 954
 955         /* Enter the interactive session. */
 956         return client_loop(have_tty, tty_flag ?
 957             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
 958 }
 959
 960 static void
 961 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
 962 {
 963         int id, len;
 964
 965         id = packet_get_int();
 966         len = buffer_len(&command);
 967         if (len > 900)
 968                 len = 900;
 969         packet_check_eom();
 970         if (type == SSH2_MSG_CHANNEL_FAILURE)
 971                 fatal("Request for subsystem '%.*s' failed on channel %d",
 972                     len, (u_char *)buffer_ptr(&command), id);
 973 }
 974
 975 void
 976 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
 977 {
 978         int i;
 979
 980         i = client_global_request_id++;
 981         if (i >= options.num_remote_forwards)
 982                 return;
 983         debug("remote forward %s for: listen %d, connect %s:%d",
 984             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
 985             options.remote_forwards[i].listen_port,
 986             options.remote_forwards[i].connect_host,
 987             options.remote_forwards[i].connect_port);
 988         if (type == SSH2_MSG_REQUEST_FAILURE)
 989                 logit("Warning: remote port forwarding failed for listen "
 990                     "port %d", options.remote_forwards[i].listen_port);
 991 }
 992
 993 static void
 994 ssh_control_listener(void)
 995 {
 996         struct sockaddr_un addr;
 997         mode_t old_umask;
 998         int addr_len;
 999
1000         if (options.control_path == NULL ||
1001             options.control_master == SSHCTL_MASTER_NO)
1002                 return;
1003
1004         debug("setting up multiplex master socket");
1005
1006         memset(&addr, '\0', sizeof(addr));
1007         addr.sun_family = AF_UNIX;
1008         addr_len = offsetof(struct sockaddr_un, sun_path) +
1009             strlen(options.control_path) + 1;
1010
1011         if (strlcpy(addr.sun_path, options.control_path,
1012             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1013                 fatal("ControlPath too long");
1014
1015         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1016                 fatal("%s socket(): %s\n", __func__, strerror(errno));
1017
1018         old_umask = umask(0177);
1019         if (bind(control_fd, (struct sockaddr*)&addr, addr_len) == -1) {
1020                 control_fd = -1;
1021                 if (errno == EINVAL || errno == EADDRINUSE)
1022                         fatal("ControlSocket %s already exists",
1023                             options.control_path);
1024                 else
1025                         fatal("%s bind(): %s\n", __func__, strerror(errno));
1026         }
1027         umask(old_umask);
1028
1029         if (listen(control_fd, 64) == -1)
1030                 fatal("%s listen(): %s\n", __func__, strerror(errno));
1031
1032         set_nonblock(control_fd);
1033 }
1034
1035 /* request pty/x11/agent/tcpfwd/shell for channel */
1036 static void
1037 ssh_session2_setup(int id, void *arg)
1038 {
1039         extern char **environ;
1040         const char *display;
1041         int interactive = tty_flag;
1042
1043         display = getenv("DISPLAY");
1044         if (options.forward_x11 && display != NULL) {
1045                 char *proto, *data;
1046                 /* Get reasonable local authentication information. */
1047                 client_x11_get_proto(display, options.xauth_location,
1048                     options.forward_x11_trusted, &proto, &data);
1049                 /* Request forwarding with authentication spoofing. */
1050                 debug("Requesting X11 forwarding with authentication spoofing.");
1051                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1052                 interactive = 1;
1053                 /* XXX wait for reply */
1054         }
1055
1056         check_agent_present();
1057         if (options.forward_agent) {
1058                 debug("Requesting authentication agent forwarding.");
1059                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1060                 packet_send();
1061         }
1062
1063         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1064             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1065
1066         packet_set_interactive(interactive);
1067 }
1068
1069 /* open new channel for a session */
1070 static int
1071 ssh_session2_open(void)
1072 {
1073         Channel *c;
1074         int window, packetmax, in, out, err;
1075
1076         if (stdin_null_flag) {
1077                 in = open(_PATH_DEVNULL, O_RDONLY);
1078         } else {
1079                 in = dup(STDIN_FILENO);
1080         }
1081         out = dup(STDOUT_FILENO);
1082         err = dup(STDERR_FILENO);
1083
1084         if (in < 0 || out < 0 || err < 0)
1085                 fatal("dup() in/out/err failed");
1086
1087         /* enable nonblocking unless tty */
1088         if (!isatty(in))
1089                 set_nonblock(in);
1090         if (!isatty(out))
1091                 set_nonblock(out);
1092         if (!isatty(err))
1093                 set_nonblock(err);
1094
1095         window = CHAN_SES_WINDOW_DEFAULT;
1096         packetmax = CHAN_SES_PACKET_DEFAULT;
1097         if (tty_flag) {
1098                 window >>= 1;
1099                 packetmax >>= 1;
1100         }
1101         c = channel_new(
1102             "session", SSH_CHANNEL_OPENING, in, out, err,
1103             window, packetmax, CHAN_EXTENDED_WRITE,
1104             "client-session", /*nonblock*/0);
1105
1106         debug3("ssh_session2_open: channel_new: %d", c->self);
1107
1108         channel_send_open(c->self);
1109         if (!no_shell_flag)
1110                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1111
1112         return c->self;
1113 }
1114
1115 static int
1116 ssh_session2(void)
1117 {
1118         int id = -1;
1119
1120         /* XXX should be pre-session */
1121         ssh_init_forwarding();
1122         ssh_control_listener();
1123
1124         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1125                 id = ssh_session2_open();
1126
1127         /* If requested, let ssh continue in the background. */
1128         if (fork_after_authentication_flag)
1129                 if (daemon(1, 1) < 0)
1130                         fatal("daemon() failed: %.200s", strerror(errno));
1131
1132         return client_loop(tty_flag, tty_flag ?
1133             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1134 }
1135
1136 static void
1137 load_public_identity_files(void)
1138 {
1139         char *filename;
1140         int i = 0;
1141         Key *public;
1142 #ifdef SMARTCARD
1143         Key **keys;
1144
1145         if (options.smartcard_device != NULL &&
1146             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1147             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1148                 int count = 0;
1149                 for (i = 0; keys[i] != NULL; i++) {
1150                         count++;
1151                         memmove(&options.identity_files[1], &options.identity_files[0],
1152                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1153                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1154                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1155                         options.num_identity_files++;
1156                         options.identity_keys[0] = keys[i];
1157                         options.identity_files[0] = sc_get_key_label(keys[i]);
1158                 }
1159                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1160                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1161                 i = count;
1162                 xfree(keys);
1163         }
1164 #endif /* SMARTCARD */
1165         for (; i < options.num_identity_files; i++) {
1166                 filename = tilde_expand_filename(options.identity_files[i],
1167                     original_real_uid);
1168                 public = key_load_public(filename, NULL);
1169                 debug("identity file %s type %d", filename,
1170                     public ? public->type : -1);
1171                 xfree(options.identity_files[i]);
1172                 options.identity_files[i] = filename;
1173                 options.identity_keys[i] = public;
1174         }
1175 }
1176
1177 static void
1178 control_client_sighandler(int signo)
1179 {
1180         control_client_terminate = signo;
1181 }
1182
1183 static void
1184 control_client_sigrelay(int signo)
1185 {
1186         if (control_server_pid > 1)
1187                 kill(control_server_pid, signo);
1188 }
1189
1190 static int
1191 env_permitted(char *env)
1192 {
1193         int i;
1194         char name[1024], *cp;
1195
1196         strlcpy(name, env, sizeof(name));
1197         if ((cp = strchr(name, '=')) == NULL)
1198                 return (0);
1199
1200         *cp = '\0';
1201
1202         for (i = 0; i < options.num_send_env; i++)
1203                 if (match_pattern(name, options.send_env[i]))
1204                         return (1);
1205
1206         return (0);
1207 }
1208
1209 static void
1210 control_client(const char *path)
1211 {
1212         struct sockaddr_un addr;
1213         int i, r, fd, sock, exitval, num_env, addr_len;
1214         Buffer m;
1215         char *term;
1216         extern char **environ;
1217         u_int  flags;
1218
1219         if (mux_command == 0)
1220                 mux_command = SSHMUX_COMMAND_OPEN;
1221
1222         switch (options.control_master) {
1223         case SSHCTL_MASTER_AUTO:
1224         case SSHCTL_MASTER_AUTO_ASK:
1225                 debug("auto-mux: Trying existing master");
1226                 /* FALLTHROUGH */
1227         case SSHCTL_MASTER_NO:
1228                 break;
1229         default:
1230                 return;
1231         }
1232
1233         memset(&addr, '\0', sizeof(addr));
1234         addr.sun_family = AF_UNIX;
1235         addr_len = offsetof(struct sockaddr_un, sun_path) +
1236             strlen(path) + 1;
1237
1238         if (strlcpy(addr.sun_path, path,
1239             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1240                 fatal("ControlPath too long");
1241
1242         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1243                 fatal("%s socket(): %s", __func__, strerror(errno));
1244
1245         if (connect(sock, (struct sockaddr*)&addr, addr_len) == -1) {
1246                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1247                         fatal("Control socket connect(%.100s): %s", path,
1248                             strerror(errno));
1249                 }
1250                 if (errno == ENOENT)
1251                         debug("Control socket \"%.100s\" does not exist", path);
1252                 else {
1253                         error("Control socket connect(%.100s): %s", path,
1254                             strerror(errno));
1255                 }
1256                 close(sock);
1257                 return;
1258         }
1259
1260         if (stdin_null_flag) {
1261                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1262                         fatal("open(/dev/null): %s", strerror(errno));
1263                 if (dup2(fd, STDIN_FILENO) == -1)
1264                         fatal("dup2: %s", strerror(errno));
1265                 if (fd > STDERR_FILENO)
1266                         close(fd);
1267         }
1268
1269         term = getenv("TERM");
1270
1271         flags = 0;
1272         if (tty_flag)
1273                 flags |= SSHMUX_FLAG_TTY;
1274         if (subsystem_flag)
1275                 flags |= SSHMUX_FLAG_SUBSYS;
1276         if (options.forward_x11)
1277                 flags |= SSHMUX_FLAG_X11_FWD;
1278         if (options.forward_agent)
1279                 flags |= SSHMUX_FLAG_AGENT_FWD;
1280
1281         buffer_init(&m);
1282
1283         /* Send our command to server */
1284         buffer_put_int(&m, mux_command);
1285         buffer_put_int(&m, flags);
1286         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1287                 fatal("%s: msg_send", __func__);
1288         buffer_clear(&m);
1289
1290         /* Get authorisation status and PID of controlee */
1291         if (ssh_msg_recv(sock, &m) == -1)
1292                 fatal("%s: msg_recv", __func__);
1293         if (buffer_get_char(&m) != SSHMUX_VER)
1294                 fatal("%s: wrong version", __func__);
1295         if (buffer_get_int(&m) != 1)
1296                 fatal("Connection to master denied");
1297         control_server_pid = buffer_get_int(&m);
1298
1299         buffer_clear(&m);
1300
1301         switch (mux_command) {
1302         case SSHMUX_COMMAND_ALIVE_CHECK:
1303                 fprintf(stderr, "Master running (pid=%d)\r\n",
1304                     control_server_pid);
1305                 exit(0);
1306         case SSHMUX_COMMAND_TERMINATE:
1307                 fprintf(stderr, "Exit request sent.\r\n");
1308                 exit(0);
1309         case SSHMUX_COMMAND_OPEN:
1310                 /* continue below */
1311                 break;
1312         default:
1313                 fatal("silly mux_command %d", mux_command);
1314         }
1315
1316         /* SSHMUX_COMMAND_OPEN */
1317         buffer_put_cstring(&m, term ? term : "");
1318         buffer_append(&command, "\0", 1);
1319         buffer_put_cstring(&m, buffer_ptr(&command));
1320
1321         if (options.num_send_env == 0 || environ == NULL) {
1322                 buffer_put_int(&m, 0);
1323         } else {
1324                 /* Pass environment */
1325                 num_env = 0;
1326                 for (i = 0; environ[i] != NULL; i++)
1327                         if (env_permitted(environ[i]))
1328                                 num_env++; /* Count */
1329
1330                 buffer_put_int(&m, num_env);
1331
1332                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1333                         if (env_permitted(environ[i])) {
1334                                 num_env--;
1335                                 buffer_put_cstring(&m, environ[i]);
1336                         }
1337         }
1338
1339         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1340                 fatal("%s: msg_send", __func__);
1341
1342         mm_send_fd(sock, STDIN_FILENO);
1343         mm_send_fd(sock, STDOUT_FILENO);
1344         mm_send_fd(sock, STDERR_FILENO);
1345
1346         /* Wait for reply, so master has a chance to gather ttymodes */
1347         buffer_clear(&m);
1348         if (ssh_msg_recv(sock, &m) == -1)
1349                 fatal("%s: msg_recv", __func__);
1350         if (buffer_get_char(&m) != SSHMUX_VER)
1351                 fatal("%s: wrong version", __func__);
1352         buffer_free(&m);
1353
1354         signal(SIGHUP, control_client_sighandler);
1355         signal(SIGINT, control_client_sighandler);
1356         signal(SIGTERM, control_client_sighandler);
1357         signal(SIGWINCH, control_client_sigrelay);
1358
1359         if (tty_flag)
1360                 enter_raw_mode();
1361
1362         /* Stick around until the controlee closes the client_fd */
1363         exitval = 0;
1364         for (;!control_client_terminate;) {
1365                 r = read(sock, &exitval, sizeof(exitval));
1366                 if (r == 0) {
1367                         debug2("Received EOF from master");
1368                         break;
1369                 }
1370                 if (r > 0)
1371                         debug2("Received exit status from master %d", exitval);
1372                 if (r == -1 && errno != EINTR)
1373                         fatal("%s: read %s", __func__, strerror(errno));
1374         }
1375
1376         if (control_client_terminate)
1377                 debug2("Exiting on signal %d", control_client_terminate);
1378
1379         close(sock);
1380
1381         leave_raw_mode();
1382
1383         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1384                 fprintf(stderr, "Connection to master closed.\r\n");
1385
1386         exit(exitval);
1387 }