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 1.259 2006/02/08 14:31:30 stevesk Exp $");
  44
  45 #include <sys/resource.h>
  46
  47 #include <paths.h>
  48
  49 #include <openssl/evp.h>
  50 #include <openssl/err.h>
  51
  52 #include "ssh.h"
  53 #include "ssh1.h"
  54 #include "ssh2.h"
  55 #include "compat.h"
  56 #include "cipher.h"
  57 #include "xmalloc.h"
  58 #include "packet.h"
  59 #include "buffer.h"
  60 #include "bufaux.h"
  61 #include "channels.h"
  62 #include "key.h"
  63 #include "authfd.h"
  64 #include "authfile.h"
  65 #include "pathnames.h"
  66 #include "dispatch.h"
  67 #include "clientloop.h"
  68 #include "log.h"
  69 #include "readconf.h"
  70 #include "sshconnect.h"
  71 #include "misc.h"
  72 #include "kex.h"
  73 #include "mac.h"
  74 #include "sshpty.h"
  75 #include "match.h"
  76 #include "msg.h"
  77 #include "monitor_fdpass.h"
  78 #include "uidswap.h"
  79
  80 #ifdef SMARTCARD
  81 #include "scard.h"
  82 #endif
  83
  84 extern char *__progname;
  85
  86 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
  87 int debug_flag = 0;
  88
  89 /* Flag indicating whether a tty should be allocated */
  90 int tty_flag = 0;
  91 int no_tty_flag = 0;
  92 int force_tty_flag = 0;
  93
  94 /* don't exec a shell */
  95 int no_shell_flag = 0;
  96
  97 /*
  98  * Flag indicating that nothing should be read from stdin.  This can be set
  99  * on the command line.
 100  */
 101 int stdin_null_flag = 0;
 102
 103 /*
 104  * Flag indicating that ssh should fork after authentication.  This is useful
 105  * so that the passphrase can be entered manually, and then ssh goes to the
 106  * background.
 107  */
 108 int fork_after_authentication_flag = 0;
 109
 110 /*
 111  * General data structure for command line options and options configurable
 112  * in configuration files.  See readconf.h.
 113  */
 114 Options options;
 115
 116 /* optional user configfile */
 117 char *config = NULL;
 118
 119 /*
 120  * Name of the host we are connecting to.  This is the name given on the
 121  * command line, or the HostName specified for the user-supplied name in a
 122  * configuration file.
 123  */
 124 char *host;
 125
 126 /* socket address the host resolves to */
 127 struct sockaddr_storage hostaddr;
 128
 129 /* Private host keys. */
 130 Sensitive sensitive_data;
 131
 132 /* Original real UID. */
 133 uid_t original_real_uid;
 134 uid_t original_effective_uid;
 135
 136 /* command to be executed */
 137 Buffer command;
 138
 139 /* Should we execute a command or invoke a subsystem? */
 140 int subsystem_flag = 0;
 141
 142 /* # of replies received for global requests */
 143 static int client_global_request_id = 0;
 144
 145 /* pid of proxycommand child process */
 146 pid_t proxy_command_pid = 0;
 147
 148 /* fd to control socket */
 149 int control_fd = -1;
 150
 151 /* Multiplexing control command */
 152 static u_int mux_command = 0;
 153
 154 /* Only used in control client mode */
 155 volatile sig_atomic_t control_client_terminate = 0;
 156 u_int control_server_pid = 0;
 157
 158 /* Prints a help message to the user.  This function never returns. */
 159
 160 static void
 161 usage(void)
 162 {
 163         fprintf(stderr,
 164 "usage: ssh [-1246AaCfgkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 165 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 166 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 167 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 168 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 169 "           [-w tunnel:tunnel] [user@]hostname [command]\n"
 170         );
 171         exit(255);
 172 }
 173
 174 static int ssh_session(void);
 175 static int ssh_session2(void);
 176 static void load_public_identity_files(void);
 177 static void control_client(const char *path);
 178
 179 /*
 180  * Main program for the ssh client.
 181  */
 182 int
 183 main(int ac, char **av)
 184 {
 185         int i, opt, exit_status;
 186         char *p, *cp, *line, buf[256];
 187         struct stat st;
 188         struct passwd *pw;
 189         int dummy;
 190         extern int optind, optreset;
 191         extern char *optarg;
 192         struct servent *sp;
 193         Forward fwd;
 194
 195         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 196         sanitise_stdfd();
 197
 198         __progname = ssh_get_progname(av[0]);
 199         init_rng();
 200
 201         /*
 202          * Save the original real uid.  It will be needed later (uid-swapping
 203          * may clobber the real uid).
 204          */
 205         original_real_uid = getuid();
 206         original_effective_uid = geteuid();
 207
 208         /*
 209          * Use uid-swapping to give up root privileges for the duration of
 210          * option processing.  We will re-instantiate the rights when we are
 211          * ready to create the privileged port, and will permanently drop
 212          * them when the port has been created (actually, when the connection
 213          * has been made, as we may need to create the port several times).
 214          */
 215         PRIV_END;
 216
 217 #ifdef HAVE_SETRLIMIT
 218         /* If we are installed setuid root be careful to not drop core. */
 219         if (original_real_uid != original_effective_uid) {
 220                 struct rlimit rlim;
 221                 rlim.rlim_cur = rlim.rlim_max = 0;
 222                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 223                         fatal("setrlimit failed: %.100s", strerror(errno));
 224         }
 225 #endif
 226         /* Get user data. */
 227         pw = getpwuid(original_real_uid);
 228         if (!pw) {
 229                 logit("You don't exist, go away!");
 230                 exit(255);
 231         }
 232         /* Take a copy of the returned structure. */
 233         pw = pwcopy(pw);
 234
 235         /*
 236          * Set our umask to something reasonable, as some files are created
 237          * with the default umask.  This will make them world-readable but
 238          * writable only by the owner, which is ok for all files for which we
 239          * don't set the modes explicitly.
 240          */
 241         umask(022);
 242
 243         /* Initialize option structure to indicate that no values have been set. */
 244         initialize_options(&options);
 245
 246         /* Parse command-line arguments. */
 247         host = NULL;
 248
 249 again:
 250         while ((opt = getopt(ac, av,
 251             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:MNO:PR:S:TVw:XY")) != -1) {
 252                 switch (opt) {
 253                 case '1':
 254                         options.protocol = SSH_PROTO_1;
 255                         break;
 256                 case '2':
 257                         options.protocol = SSH_PROTO_2;
 258                         break;
 259                 case '4':
 260                         options.address_family = AF_INET;
 261                         break;
 262                 case '6':
 263                         options.address_family = AF_INET6;
 264                         break;
 265                 case 'n':
 266                         stdin_null_flag = 1;
 267                         break;
 268                 case 'f':
 269                         fork_after_authentication_flag = 1;
 270                         stdin_null_flag = 1;
 271                         break;
 272                 case 'x':
 273                         options.forward_x11 = 0;
 274                         break;
 275                 case 'X':
 276                         options.forward_x11 = 1;
 277                         break;
 278                 case 'Y':
 279                         options.forward_x11 = 1;
 280                         options.forward_x11_trusted = 1;
 281                         break;
 282                 case 'g':
 283                         options.gateway_ports = 1;
 284                         break;
 285                 case 'O':
 286                         if (strcmp(optarg, "check") == 0)
 287                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 288                         else if (strcmp(optarg, "exit") == 0)
 289                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 290                         else
 291                                 fatal("Invalid multiplex command.");
 292                         break;
 293                 case 'P':       /* deprecated */
 294                         options.use_privileged_port = 0;
 295                         break;
 296                 case 'a':
 297                         options.forward_agent = 0;
 298                         break;
 299                 case 'A':
 300                         options.forward_agent = 1;
 301                         break;
 302                 case 'k':
 303                         options.gss_deleg_creds = 0;
 304                         break;
 305                 case 'i':
 306                         if (stat(optarg, &st) < 0) {
 307                                 fprintf(stderr, "Warning: Identity file %s "
 308                                     "not accessible: %s.\n", optarg,
 309                                     strerror(errno));
 310                                 break;
 311                         }
 312                         if (options.num_identity_files >=
 313                             SSH_MAX_IDENTITY_FILES)
 314                                 fatal("Too many identity files specified "
 315                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 316                         options.identity_files[options.num_identity_files++] =
 317                             xstrdup(optarg);
 318                         break;
 319                 case 'I':
 320 #ifdef SMARTCARD
 321                         options.smartcard_device = xstrdup(optarg);
 322 #else
 323                         fprintf(stderr, "no support for smartcards.\n");
 324 #endif
 325                         break;
 326                 case 't':
 327                         if (tty_flag)
 328                                 force_tty_flag = 1;
 329                         tty_flag = 1;
 330                         break;
 331                 case 'v':
 332                         if (debug_flag == 0) {
 333                                 debug_flag = 1;
 334                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 335                         } else {
 336                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 337                                         options.log_level++;
 338                                 break;
 339                         }
 340                         /* FALLTHROUGH */
 341                 case 'V':
 342                         fprintf(stderr, "%s, %s\n",
 343                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 344                         if (opt == 'V')
 345                                 exit(0);
 346                         break;
 347                 case 'w':
 348                         if (options.tun_open == -1)
 349                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 350                         options.tun_local = a2tun(optarg, &options.tun_remote);
 351                         if (options.tun_local == SSH_TUNID_ERR) {
 352                                 fprintf(stderr, "Bad tun device '%s'\n", optarg);
 353                                 exit(255);
 354                         }
 355                         break;
 356                 case 'q':
 357                         options.log_level = SYSLOG_LEVEL_QUIET;
 358                         break;
 359                 case 'e':
 360                         if (optarg[0] == '^' && optarg[2] == 0 &&
 361                             (u_char) optarg[1] >= 64 &&
 362                             (u_char) optarg[1] < 128)
 363                                 options.escape_char = (u_char) optarg[1] & 31;
 364                         else if (strlen(optarg) == 1)
 365                                 options.escape_char = (u_char) optarg[0];
 366                         else if (strcmp(optarg, "none") == 0)
 367                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 368                         else {
 369                                 fprintf(stderr, "Bad escape character '%s'.\n",
 370                                     optarg);
 371                                 exit(255);
 372                         }
 373                         break;
 374                 case 'c':
 375                         if (ciphers_valid(optarg)) {
 376                                 /* SSH2 only */
 377                                 options.ciphers = xstrdup(optarg);
 378                                 options.cipher = SSH_CIPHER_INVALID;
 379                         } else {
 380                                 /* SSH1 only */
 381                                 options.cipher = cipher_number(optarg);
 382                                 if (options.cipher == -1) {
 383                                         fprintf(stderr,
 384                                             "Unknown cipher type '%s'\n",
 385                                             optarg);
 386                                         exit(255);
 387                                 }
 388                                 if (options.cipher == SSH_CIPHER_3DES)
 389                                         options.ciphers = "3des-cbc";
 390                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 391                                         options.ciphers = "blowfish-cbc";
 392                                 else
 393                                         options.ciphers = (char *)-1;
 394                         }
 395                         break;
 396                 case 'm':
 397                         if (mac_valid(optarg))
 398                                 options.macs = xstrdup(optarg);
 399                         else {
 400                                 fprintf(stderr, "Unknown mac type '%s'\n",
 401                                     optarg);
 402                                 exit(255);
 403                         }
 404                         break;
 405                 case 'M':
 406                         if (options.control_master == SSHCTL_MASTER_YES)
 407                                 options.control_master = SSHCTL_MASTER_ASK;
 408                         else
 409                                 options.control_master = SSHCTL_MASTER_YES;
 410                         break;
 411                 case 'p':
 412                         options.port = a2port(optarg);
 413                         if (options.port == 0) {
 414                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 415                                 exit(255);
 416                         }
 417                         break;
 418                 case 'l':
 419                         options.user = optarg;
 420                         break;
 421
 422                 case 'L':
 423                         if (parse_forward(&fwd, optarg))
 424                                 add_local_forward(&options, &fwd);
 425                         else {
 426                                 fprintf(stderr,
 427                                     "Bad local forwarding specification '%s'\n",
 428                                     optarg);
 429                                 exit(255);
 430                         }
 431                         break;
 432
 433                 case 'R':
 434                         if (parse_forward(&fwd, optarg)) {
 435                                 add_remote_forward(&options, &fwd);
 436                         } else {
 437                                 fprintf(stderr,
 438                                     "Bad remote forwarding specification "
 439                                     "'%s'\n", optarg);
 440                                 exit(255);
 441                         }
 442                         break;
 443
 444                 case 'D':
 445                         cp = p = xstrdup(optarg);
 446                         memset(&fwd, '\0', sizeof(fwd));
 447                         fwd.connect_host = "socks";
 448                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 449                                 fprintf(stderr, "Bad dynamic forwarding "
 450                                     "specification '%.100s'\n", optarg);
 451                                 exit(255);
 452                         }
 453                         if (cp != NULL) {
 454                                 fwd.listen_port = a2port(cp);
 455                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 456                         } else {
 457                                 fwd.listen_port = a2port(fwd.listen_host);
 458                                 fwd.listen_host = NULL;
 459                         }
 460
 461                         if (fwd.listen_port == 0) {
 462                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 463                                     optarg);
 464                                 exit(255);
 465                         }
 466                         add_local_forward(&options, &fwd);
 467                         xfree(p);
 468                         break;
 469
 470                 case 'C':
 471                         options.compression = 1;
 472                         break;
 473                 case 'N':
 474                         no_shell_flag = 1;
 475                         no_tty_flag = 1;
 476                         break;
 477                 case 'T':
 478                         no_tty_flag = 1;
 479                         break;
 480                 case 'o':
 481                         dummy = 1;
 482                         line = xstrdup(optarg);
 483                         if (process_config_line(&options, host ? host : "",
 484                             line, "command-line", 0, &dummy) != 0)
 485                                 exit(255);
 486                         xfree(line);
 487                         break;
 488                 case 's':
 489                         subsystem_flag = 1;
 490                         break;
 491                 case 'S':
 492                         if (options.control_path != NULL)
 493                                 free(options.control_path);
 494                         options.control_path = xstrdup(optarg);
 495                         break;
 496                 case 'b':
 497                         options.bind_address = optarg;
 498                         break;
 499                 case 'F':
 500                         config = optarg;
 501                         break;
 502                 default:
 503                         usage();
 504                 }
 505         }
 506
 507         ac -= optind;
 508         av += optind;
 509
 510         if (ac > 0 && !host && **av != '-') {
 511                 if (strrchr(*av, '@')) {
 512                         p = xstrdup(*av);
 513                         cp = strrchr(p, '@');
 514                         if (cp == NULL || cp == p)
 515                                 usage();
 516                         options.user = p;
 517                         *cp = '\0';
 518                         host = ++cp;
 519                 } else
 520                         host = *av;
 521                 if (ac > 1) {
 522                         optind = optreset = 1;
 523                         goto again;
 524                 }
 525                 ac--, av++;
 526         }
 527
 528         /* Check that we got a host name. */
 529         if (!host)
 530                 usage();
 531
 532         SSLeay_add_all_algorithms();
 533         ERR_load_crypto_strings();
 534
 535         /* Initialize the command to execute on remote host. */
 536         buffer_init(&command);
 537
 538         /*
 539          * Save the command to execute on the remote host in a buffer. There
 540          * is no limit on the length of the command, except by the maximum
 541          * packet size.  Also sets the tty flag if there is no command.
 542          */
 543         if (!ac) {
 544                 /* No command specified - execute shell on a tty. */
 545                 tty_flag = 1;
 546                 if (subsystem_flag) {
 547                         fprintf(stderr,
 548                             "You must specify a subsystem to invoke.\n");
 549                         usage();
 550                 }
 551         } else {
 552                 /* A command has been specified.  Store it into the buffer. */
 553                 for (i = 0; i < ac; i++) {
 554                         if (i)
 555                                 buffer_append(&command, " ", 1);
 556                         buffer_append(&command, av[i], strlen(av[i]));
 557                 }
 558         }
 559
 560         /* Cannot fork to background if no command. */
 561         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 562                 fatal("Cannot fork into background without a command to execute.");
 563
 564         /* Allocate a tty by default if no command specified. */
 565         if (buffer_len(&command) == 0)
 566                 tty_flag = 1;
 567
 568         /* Force no tty */
 569         if (no_tty_flag)
 570                 tty_flag = 0;
 571         /* Do not allocate a tty if stdin is not a tty. */
 572         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 573                 if (tty_flag)
 574                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 575                 tty_flag = 0;
 576         }
 577
 578         /*
 579          * Initialize "log" output.  Since we are the client all output
 580          * actually goes to stderr.
 581          */
 582         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 583             SYSLOG_FACILITY_USER, 1);
 584
 585         /*
 586          * Read per-user configuration file.  Ignore the system wide config
 587          * file if the user specifies a config file on the command line.
 588          */
 589         if (config != NULL) {
 590                 if (!read_config_file(config, host, &options, 0))
 591                         fatal("Can't open user config file %.100s: "
 592                             "%.100s", config, strerror(errno));
 593         } else  {
 594                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 595                     _PATH_SSH_USER_CONFFILE);
 596                 (void)read_config_file(buf, host, &options, 1);
 597
 598                 /* Read systemwide configuration file after use config. */
 599                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 600                     &options, 0);
 601         }
 602
 603         /* Fill configuration defaults. */
 604         fill_default_options(&options);
 605
 606         channel_set_af(options.address_family);
 607
 608         /* reinit */
 609         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 610
 611         seed_rng();
 612
 613         if (options.user == NULL)
 614                 options.user = xstrdup(pw->pw_name);
 615
 616         if (options.hostname != NULL)
 617                 host = options.hostname;
 618
 619         /* force lowercase for hostkey matching */
 620         if (options.host_key_alias != NULL) {
 621                 for (p = options.host_key_alias; *p; p++)
 622                         if (isupper(*p))
 623                                 *p = tolower(*p);
 624         }
 625
 626         /* Get default port if port has not been set. */
 627         if (options.port == 0) {
 628                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 629                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 630         }
 631
 632         if (options.proxy_command != NULL &&
 633             strcmp(options.proxy_command, "none") == 0)
 634                 options.proxy_command = NULL;
 635         if (options.control_path != NULL &&
 636             strcmp(options.control_path, "none") == 0)
 637                 options.control_path = NULL;
 638
 639         if (options.control_path != NULL) {
 640                 snprintf(buf, sizeof(buf), "%d", options.port);
 641                 cp = tilde_expand_filename(options.control_path,
 642                     original_real_uid);
 643                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 644                     "r", options.user, (char *)NULL);
 645                 xfree(cp);
 646         }
 647         if (mux_command != 0 && options.control_path == NULL)
 648                 fatal("No ControlPath specified for \"-O\" command");
 649         if (options.control_path != NULL)
 650                 control_client(options.control_path);
 651
 652         /* Open a connection to the remote host. */
 653         if (ssh_connect(host, &hostaddr, options.port,
 654             options.address_family, options.connection_attempts,
 655 #ifdef HAVE_CYGWIN
 656             options.use_privileged_port,
 657 #else
 658             original_effective_uid == 0 && options.use_privileged_port,
 659 #endif
 660             options.proxy_command) != 0)
 661                 exit(255);
 662
 663         /*
 664          * If we successfully made the connection, load the host private key
 665          * in case we will need it later for combined rsa-rhosts
 666          * authentication. This must be done before releasing extra
 667          * privileges, because the file is only readable by root.
 668          * If we cannot access the private keys, load the public keys
 669          * instead and try to execute the ssh-keysign helper instead.
 670          */
 671         sensitive_data.nkeys = 0;
 672         sensitive_data.keys = NULL;
 673         sensitive_data.external_keysign = 0;
 674         if (options.rhosts_rsa_authentication ||
 675             options.hostbased_authentication) {
 676                 sensitive_data.nkeys = 3;
 677                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 678                     sizeof(Key));
 679
 680                 PRIV_START;
 681                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 682                     _PATH_HOST_KEY_FILE, "", NULL);
 683                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 684                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 685                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 686                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 687                 PRIV_END;
 688
 689                 if (options.hostbased_authentication == 1 &&
 690                     sensitive_data.keys[0] == NULL &&
 691                     sensitive_data.keys[1] == NULL &&
 692                     sensitive_data.keys[2] == NULL) {
 693                         sensitive_data.keys[1] = key_load_public(
 694                             _PATH_HOST_DSA_KEY_FILE, NULL);
 695                         sensitive_data.keys[2] = key_load_public(
 696                             _PATH_HOST_RSA_KEY_FILE, NULL);
 697                         sensitive_data.external_keysign = 1;
 698                 }
 699         }
 700         /*
 701          * Get rid of any extra privileges that we may have.  We will no
 702          * longer need them.  Also, extra privileges could make it very hard
 703          * to read identity files and other non-world-readable files from the
 704          * user's home directory if it happens to be on a NFS volume where
 705          * root is mapped to nobody.
 706          */
 707         if (original_effective_uid == 0) {
 708                 PRIV_START;
 709                 permanently_set_uid(pw);
 710         }
 711
 712         /*
 713          * Now that we are back to our own permissions, create ~/.ssh
 714          * directory if it doesn't already exist.
 715          */
 716         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 717         if (stat(buf, &st) < 0)
 718                 if (mkdir(buf, 0700) < 0)
 719                         error("Could not create directory '%.200s'.", buf);
 720
 721         /* load options.identity_files */
 722         load_public_identity_files();
 723
 724         /* Expand ~ in known host file names. */
 725         /* XXX mem-leaks: */
 726         options.system_hostfile =
 727             tilde_expand_filename(options.system_hostfile, original_real_uid);
 728         options.user_hostfile =
 729             tilde_expand_filename(options.user_hostfile, original_real_uid);
 730         options.system_hostfile2 =
 731             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 732         options.user_hostfile2 =
 733             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 734
 735         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 736
 737         /* Log into the remote system.  This never returns if the login fails. */
 738         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 739
 740         /* We no longer need the private host keys.  Clear them now. */
 741         if (sensitive_data.nkeys != 0) {
 742                 for (i = 0; i < sensitive_data.nkeys; i++) {
 743                         if (sensitive_data.keys[i] != NULL) {
 744                                 /* Destroys contents safely */
 745                                 debug3("clear hostkey %d", i);
 746                                 key_free(sensitive_data.keys[i]);
 747                                 sensitive_data.keys[i] = NULL;
 748                         }
 749                 }
 750                 xfree(sensitive_data.keys);
 751         }
 752         for (i = 0; i < options.num_identity_files; i++) {
 753                 if (options.identity_files[i]) {
 754                         xfree(options.identity_files[i]);
 755                         options.identity_files[i] = NULL;
 756                 }
 757                 if (options.identity_keys[i]) {
 758                         key_free(options.identity_keys[i]);
 759                         options.identity_keys[i] = NULL;
 760                 }
 761         }
 762
 763         exit_status = compat20 ? ssh_session2() : ssh_session();
 764         packet_close();
 765
 766         if (options.control_path != NULL && control_fd != -1)
 767                 unlink(options.control_path);
 768
 769         /*
 770          * Send SIGHUP to proxy command if used. We don't wait() in
 771          * case it hangs and instead rely on init to reap the child
 772          */
 773         if (proxy_command_pid > 1)
 774                 kill(proxy_command_pid, SIGHUP);
 775
 776         return exit_status;
 777 }
 778
 779 static void
 780 ssh_init_forwarding(void)
 781 {
 782         int success = 0;
 783         int i;
 784
 785         /* Initiate local TCP/IP port forwardings. */
 786         for (i = 0; i < options.num_local_forwards; i++) {
 787                 debug("Local connections to %.200s:%d forwarded to remote "
 788                     "address %.200s:%d",
 789                     (options.local_forwards[i].listen_host == NULL) ?
 790                     (options.gateway_ports ? "*" : "LOCALHOST") :
 791                     options.local_forwards[i].listen_host,
 792                     options.local_forwards[i].listen_port,
 793                     options.local_forwards[i].connect_host,
 794                     options.local_forwards[i].connect_port);
 795                 success += channel_setup_local_fwd_listener(
 796                     options.local_forwards[i].listen_host,
 797                     options.local_forwards[i].listen_port,
 798                     options.local_forwards[i].connect_host,
 799                     options.local_forwards[i].connect_port,
 800                     options.gateway_ports);
 801         }
 802         if (i > 0 && success == 0)
 803                 error("Could not request local forwarding.");
 804
 805         /* Initiate remote TCP/IP port forwardings. */
 806         for (i = 0; i < options.num_remote_forwards; i++) {
 807                 debug("Remote connections from %.200s:%d forwarded to "
 808                     "local address %.200s:%d",
 809                     (options.remote_forwards[i].listen_host == NULL) ?
 810                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 811                     options.remote_forwards[i].listen_port,
 812                     options.remote_forwards[i].connect_host,
 813                     options.remote_forwards[i].connect_port);
 814                 channel_request_remote_forwarding(
 815                     options.remote_forwards[i].listen_host,
 816                     options.remote_forwards[i].listen_port,
 817                     options.remote_forwards[i].connect_host,
 818                     options.remote_forwards[i].connect_port);
 819         }
 820 }
 821
 822 static void
 823 check_agent_present(void)
 824 {
 825         if (options.forward_agent) {
 826                 /* Clear agent forwarding if we don't have an agent. */
 827                 if (!ssh_agent_present())
 828                         options.forward_agent = 0;
 829         }
 830 }
 831
 832 static int
 833 ssh_session(void)
 834 {
 835         int type;
 836         int interactive = 0;
 837         int have_tty = 0;
 838         struct winsize ws;
 839         char *cp;
 840         const char *display;
 841
 842         /* Enable compression if requested. */
 843         if (options.compression) {
 844                 debug("Requesting compression at level %d.", options.compression_level);
 845
 846                 if (options.compression_level < 1 || options.compression_level > 9)
 847                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 848
 849                 /* Send the request. */
 850                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 851                 packet_put_int(options.compression_level);
 852                 packet_send();
 853                 packet_write_wait();
 854                 type = packet_read();
 855                 if (type == SSH_SMSG_SUCCESS)
 856                         packet_start_compression(options.compression_level);
 857                 else if (type == SSH_SMSG_FAILURE)
 858                         logit("Warning: Remote host refused compression.");
 859                 else
 860                         packet_disconnect("Protocol error waiting for compression response.");
 861         }
 862         /* Allocate a pseudo tty if appropriate. */
 863         if (tty_flag) {
 864                 debug("Requesting pty.");
 865
 866                 /* Start the packet. */
 867                 packet_start(SSH_CMSG_REQUEST_PTY);
 868
 869                 /* Store TERM in the packet.  There is no limit on the
 870                    length of the string. */
 871                 cp = getenv("TERM");
 872                 if (!cp)
 873                         cp = "";
 874                 packet_put_cstring(cp);
 875
 876                 /* Store window size in the packet. */
 877                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 878                         memset(&ws, 0, sizeof(ws));
 879                 packet_put_int(ws.ws_row);
 880                 packet_put_int(ws.ws_col);
 881                 packet_put_int(ws.ws_xpixel);
 882                 packet_put_int(ws.ws_ypixel);
 883
 884                 /* Store tty modes in the packet. */
 885                 tty_make_modes(fileno(stdin), NULL);
 886
 887                 /* Send the packet, and wait for it to leave. */
 888                 packet_send();
 889                 packet_write_wait();
 890
 891                 /* Read response from the server. */
 892                 type = packet_read();
 893                 if (type == SSH_SMSG_SUCCESS) {
 894                         interactive = 1;
 895                         have_tty = 1;
 896                 } else if (type == SSH_SMSG_FAILURE)
 897                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 898                 else
 899                         packet_disconnect("Protocol error waiting for pty request response.");
 900         }
 901         /* Request X11 forwarding if enabled and DISPLAY is set. */
 902         display = getenv("DISPLAY");
 903         if (options.forward_x11 && display != NULL) {
 904                 char *proto, *data;
 905                 /* Get reasonable local authentication information. */
 906                 client_x11_get_proto(display, options.xauth_location,
 907                     options.forward_x11_trusted, &proto, &data);
 908                 /* Request forwarding with authentication spoofing. */
 909                 debug("Requesting X11 forwarding with authentication spoofing.");
 910                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 911
 912                 /* Read response from the server. */
 913                 type = packet_read();
 914                 if (type == SSH_SMSG_SUCCESS) {
 915                         interactive = 1;
 916                 } else if (type == SSH_SMSG_FAILURE) {
 917                         logit("Warning: Remote host denied X11 forwarding.");
 918                 } else {
 919                         packet_disconnect("Protocol error waiting for X11 forwarding");
 920                 }
 921         }
 922         /* Tell the packet module whether this is an interactive session. */
 923         packet_set_interactive(interactive);
 924
 925         /* Request authentication agent forwarding if appropriate. */
 926         check_agent_present();
 927
 928         if (options.forward_agent) {
 929                 debug("Requesting authentication agent forwarding.");
 930                 auth_request_forwarding();
 931
 932                 /* Read response from the server. */
 933                 type = packet_read();
 934                 packet_check_eom();
 935                 if (type != SSH_SMSG_SUCCESS)
 936                         logit("Warning: Remote host denied authentication agent forwarding.");
 937         }
 938
 939         /* Initiate port forwardings. */
 940         ssh_init_forwarding();
 941
 942         /* If requested, let ssh continue in the background. */
 943         if (fork_after_authentication_flag)
 944                 if (daemon(1, 1) < 0)
 945                         fatal("daemon() failed: %.200s", strerror(errno));
 946
 947         /*
 948          * If a command was specified on the command line, execute the
 949          * command now. Otherwise request the server to start a shell.
 950          */
 951         if (buffer_len(&command) > 0) {
 952                 int len = buffer_len(&command);
 953                 if (len > 900)
 954                         len = 900;
 955                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 956                 packet_start(SSH_CMSG_EXEC_CMD);
 957                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 958                 packet_send();
 959                 packet_write_wait();
 960         } else {
 961                 debug("Requesting shell.");
 962                 packet_start(SSH_CMSG_EXEC_SHELL);
 963                 packet_send();
 964                 packet_write_wait();
 965         }
 966
 967         /* Enter the interactive session. */
 968         return client_loop(have_tty, tty_flag ?
 969             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
 970 }
 971
 972 static void
 973 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
 974 {
 975         int id, len;
 976
 977         id = packet_get_int();
 978         len = buffer_len(&command);
 979         if (len > 900)
 980                 len = 900;
 981         packet_check_eom();
 982         if (type == SSH2_MSG_CHANNEL_FAILURE)
 983                 fatal("Request for subsystem '%.*s' failed on channel %d",
 984                     len, (u_char *)buffer_ptr(&command), id);
 985 }
 986
 987 void
 988 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
 989 {
 990         int i;
 991
 992         i = client_global_request_id++;
 993         if (i >= options.num_remote_forwards)
 994                 return;
 995         debug("remote forward %s for: listen %d, connect %s:%d",
 996             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
 997             options.remote_forwards[i].listen_port,
 998             options.remote_forwards[i].connect_host,
 999             options.remote_forwards[i].connect_port);
1000         if (type == SSH2_MSG_REQUEST_FAILURE)
1001                 logit("Warning: remote port forwarding failed for listen "
1002                     "port %d", options.remote_forwards[i].listen_port);
1003 }
1004
1005 static void
1006 ssh_control_listener(void)
1007 {
1008         struct sockaddr_un addr;
1009         mode_t old_umask;
1010         int addr_len;
1011
1012         if (options.control_path == NULL ||
1013             options.control_master == SSHCTL_MASTER_NO)
1014                 return;
1015
1016         debug("setting up multiplex master socket");
1017
1018         memset(&addr, '\0', sizeof(addr));
1019         addr.sun_family = AF_UNIX;
1020         addr_len = offsetof(struct sockaddr_un, sun_path) +
1021             strlen(options.control_path) + 1;
1022
1023         if (strlcpy(addr.sun_path, options.control_path,
1024             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1025                 fatal("ControlPath too long");
1026
1027         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1028                 fatal("%s socket(): %s", __func__, strerror(errno));
1029
1030         old_umask = umask(0177);
1031         if (bind(control_fd, (struct sockaddr*)&addr, addr_len) == -1) {
1032                 control_fd = -1;
1033                 if (errno == EINVAL || errno == EADDRINUSE)
1034                         fatal("ControlSocket %s already exists",
1035                             options.control_path);
1036                 else
1037                         fatal("%s bind(): %s", __func__, strerror(errno));
1038         }
1039         umask(old_umask);
1040
1041         if (listen(control_fd, 64) == -1)
1042                 fatal("%s listen(): %s", __func__, strerror(errno));
1043
1044         set_nonblock(control_fd);
1045 }
1046
1047 /* request pty/x11/agent/tcpfwd/shell for channel */
1048 static void
1049 ssh_session2_setup(int id, void *arg)
1050 {
1051         extern char **environ;
1052         const char *display;
1053         int interactive = tty_flag;
1054
1055         display = getenv("DISPLAY");
1056         if (options.forward_x11 && display != NULL) {
1057                 char *proto, *data;
1058                 /* Get reasonable local authentication information. */
1059                 client_x11_get_proto(display, options.xauth_location,
1060                     options.forward_x11_trusted, &proto, &data);
1061                 /* Request forwarding with authentication spoofing. */
1062                 debug("Requesting X11 forwarding with authentication spoofing.");
1063                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1064                 interactive = 1;
1065                 /* XXX wait for reply */
1066         }
1067
1068         check_agent_present();
1069         if (options.forward_agent) {
1070                 debug("Requesting authentication agent forwarding.");
1071                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1072                 packet_send();
1073         }
1074
1075         if (options.tun_open != SSH_TUNMODE_NO) {
1076                 Channel *c;
1077                 int fd;
1078
1079                 debug("Requesting tun.");
1080                 if ((fd = tun_open(options.tun_local,
1081                     options.tun_open)) >= 0) {
1082                         c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1083                             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1084                             0, "tun", 1);
1085                         c->datagram = 1;
1086 #if defined(SSH_TUN_FILTER)
1087                         if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
1088                                 channel_register_filter(c->self, sys_tun_infilter,
1089                                     sys_tun_outfilter);
1090 #endif
1091                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1092                         packet_put_cstring("tun@openssh.com");
1093                         packet_put_int(c->self);
1094                         packet_put_int(c->local_window_max);
1095                         packet_put_int(c->local_maxpacket);
1096                         packet_put_int(options.tun_open);
1097                         packet_put_int(options.tun_remote);
1098                         packet_send();
1099                 }
1100         }
1101
1102         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1103             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1104
1105         packet_set_interactive(interactive);
1106 }
1107
1108 /* open new channel for a session */
1109 static int
1110 ssh_session2_open(void)
1111 {
1112         Channel *c;
1113         int window, packetmax, in, out, err;
1114
1115         if (stdin_null_flag) {
1116                 in = open(_PATH_DEVNULL, O_RDONLY);
1117         } else {
1118                 in = dup(STDIN_FILENO);
1119         }
1120         out = dup(STDOUT_FILENO);
1121         err = dup(STDERR_FILENO);
1122
1123         if (in < 0 || out < 0 || err < 0)
1124                 fatal("dup() in/out/err failed");
1125
1126         /* enable nonblocking unless tty */
1127         if (!isatty(in))
1128                 set_nonblock(in);
1129         if (!isatty(out))
1130                 set_nonblock(out);
1131         if (!isatty(err))
1132                 set_nonblock(err);
1133
1134         window = CHAN_SES_WINDOW_DEFAULT;
1135         packetmax = CHAN_SES_PACKET_DEFAULT;
1136         if (tty_flag) {
1137                 window >>= 1;
1138                 packetmax >>= 1;
1139         }
1140         c = channel_new(
1141             "session", SSH_CHANNEL_OPENING, in, out, err,
1142             window, packetmax, CHAN_EXTENDED_WRITE,
1143             "client-session", /*nonblock*/0);
1144
1145         debug3("ssh_session2_open: channel_new: %d", c->self);
1146
1147         channel_send_open(c->self);
1148         if (!no_shell_flag)
1149                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1150
1151         return c->self;
1152 }
1153
1154 static int
1155 ssh_session2(void)
1156 {
1157         int id = -1;
1158
1159         /* XXX should be pre-session */
1160         ssh_init_forwarding();
1161         ssh_control_listener();
1162
1163         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1164                 id = ssh_session2_open();
1165
1166         /* Execute a local command */
1167         if (options.local_command != NULL &&
1168             options.permit_local_command)
1169                 ssh_local_cmd(options.local_command);
1170
1171         /* If requested, let ssh continue in the background. */
1172         if (fork_after_authentication_flag)
1173                 if (daemon(1, 1) < 0)
1174                         fatal("daemon() failed: %.200s", strerror(errno));
1175
1176         return client_loop(tty_flag, tty_flag ?
1177             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1178 }
1179
1180 static void
1181 load_public_identity_files(void)
1182 {
1183         char *filename;
1184         int i = 0;
1185         Key *public;
1186 #ifdef SMARTCARD
1187         Key **keys;
1188
1189         if (options.smartcard_device != NULL &&
1190             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1191             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1192                 int count = 0;
1193                 for (i = 0; keys[i] != NULL; i++) {
1194                         count++;
1195                         memmove(&options.identity_files[1], &options.identity_files[0],
1196                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1197                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1198                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1199                         options.num_identity_files++;
1200                         options.identity_keys[0] = keys[i];
1201                         options.identity_files[0] = sc_get_key_label(keys[i]);
1202                 }
1203                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1204                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1205                 i = count;
1206                 xfree(keys);
1207         }
1208 #endif /* SMARTCARD */
1209         for (; i < options.num_identity_files; i++) {
1210                 filename = tilde_expand_filename(options.identity_files[i],
1211                     original_real_uid);
1212                 public = key_load_public(filename, NULL);
1213                 debug("identity file %s type %d", filename,
1214                     public ? public->type : -1);
1215                 xfree(options.identity_files[i]);
1216                 options.identity_files[i] = filename;
1217                 options.identity_keys[i] = public;
1218         }
1219 }
1220
1221 static void
1222 control_client_sighandler(int signo)
1223 {
1224         control_client_terminate = signo;
1225 }
1226
1227 static void
1228 control_client_sigrelay(int signo)
1229 {
1230         if (control_server_pid > 1)
1231                 kill(control_server_pid, signo);
1232 }
1233
1234 static int
1235 env_permitted(char *env)
1236 {
1237         int i;
1238         char name[1024], *cp;
1239
1240         strlcpy(name, env, sizeof(name));
1241         if ((cp = strchr(name, '=')) == NULL)
1242                 return (0);
1243
1244         *cp = '\0';
1245
1246         for (i = 0; i < options.num_send_env; i++)
1247                 if (match_pattern(name, options.send_env[i]))
1248                         return (1);
1249
1250         return (0);
1251 }
1252
1253 static void
1254 control_client(const char *path)
1255 {
1256         struct sockaddr_un addr;
1257         int i, r, fd, sock, exitval, num_env, addr_len;
1258         Buffer m;
1259         char *term;
1260         extern char **environ;
1261         u_int  flags;
1262
1263         if (mux_command == 0)
1264                 mux_command = SSHMUX_COMMAND_OPEN;
1265
1266         switch (options.control_master) {
1267         case SSHCTL_MASTER_AUTO:
1268         case SSHCTL_MASTER_AUTO_ASK:
1269                 debug("auto-mux: Trying existing master");
1270                 /* FALLTHROUGH */
1271         case SSHCTL_MASTER_NO:
1272                 break;
1273         default:
1274                 return;
1275         }
1276
1277         memset(&addr, '\0', sizeof(addr));
1278         addr.sun_family = AF_UNIX;
1279         addr_len = offsetof(struct sockaddr_un, sun_path) +
1280             strlen(path) + 1;
1281
1282         if (strlcpy(addr.sun_path, path,
1283             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1284                 fatal("ControlPath too long");
1285
1286         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1287                 fatal("%s socket(): %s", __func__, strerror(errno));
1288
1289         if (connect(sock, (struct sockaddr*)&addr, addr_len) == -1) {
1290                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1291                         fatal("Control socket connect(%.100s): %s", path,
1292                             strerror(errno));
1293                 }
1294                 if (errno == ENOENT)
1295                         debug("Control socket \"%.100s\" does not exist", path);
1296                 else {
1297                         error("Control socket connect(%.100s): %s", path,
1298                             strerror(errno));
1299                 }
1300                 close(sock);
1301                 return;
1302         }
1303
1304         if (stdin_null_flag) {
1305                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1306                         fatal("open(/dev/null): %s", strerror(errno));
1307                 if (dup2(fd, STDIN_FILENO) == -1)
1308                         fatal("dup2: %s", strerror(errno));
1309                 if (fd > STDERR_FILENO)
1310                         close(fd);
1311         }
1312
1313         term = getenv("TERM");
1314
1315         flags = 0;
1316         if (tty_flag)
1317                 flags |= SSHMUX_FLAG_TTY;
1318         if (subsystem_flag)
1319                 flags |= SSHMUX_FLAG_SUBSYS;
1320         if (options.forward_x11)
1321                 flags |= SSHMUX_FLAG_X11_FWD;
1322         if (options.forward_agent)
1323                 flags |= SSHMUX_FLAG_AGENT_FWD;
1324
1325         buffer_init(&m);
1326
1327         /* Send our command to server */
1328         buffer_put_int(&m, mux_command);
1329         buffer_put_int(&m, flags);
1330         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1331                 fatal("%s: msg_send", __func__);
1332         buffer_clear(&m);
1333
1334         /* Get authorisation status and PID of controlee */
1335         if (ssh_msg_recv(sock, &m) == -1)
1336                 fatal("%s: msg_recv", __func__);
1337         if (buffer_get_char(&m) != SSHMUX_VER)
1338                 fatal("%s: wrong version", __func__);
1339         if (buffer_get_int(&m) != 1)
1340                 fatal("Connection to master denied");
1341         control_server_pid = buffer_get_int(&m);
1342
1343         buffer_clear(&m);
1344
1345         switch (mux_command) {
1346         case SSHMUX_COMMAND_ALIVE_CHECK:
1347                 fprintf(stderr, "Master running (pid=%d)\r\n",
1348                     control_server_pid);
1349                 exit(0);
1350         case SSHMUX_COMMAND_TERMINATE:
1351                 fprintf(stderr, "Exit request sent.\r\n");
1352                 exit(0);
1353         case SSHMUX_COMMAND_OPEN:
1354                 /* continue below */
1355                 break;
1356         default:
1357                 fatal("silly mux_command %d", mux_command);
1358         }
1359
1360         /* SSHMUX_COMMAND_OPEN */
1361         buffer_put_cstring(&m, term ? term : "");
1362         buffer_append(&command, "\0", 1);
1363         buffer_put_cstring(&m, buffer_ptr(&command));
1364
1365         if (options.num_send_env == 0 || environ == NULL) {
1366                 buffer_put_int(&m, 0);
1367         } else {
1368                 /* Pass environment */
1369                 num_env = 0;
1370                 for (i = 0; environ[i] != NULL; i++)
1371                         if (env_permitted(environ[i]))
1372                                 num_env++; /* Count */
1373
1374                 buffer_put_int(&m, num_env);
1375
1376                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1377                         if (env_permitted(environ[i])) {
1378                                 num_env--;
1379                                 buffer_put_cstring(&m, environ[i]);
1380                         }
1381         }
1382
1383         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1384                 fatal("%s: msg_send", __func__);
1385
1386         mm_send_fd(sock, STDIN_FILENO);
1387         mm_send_fd(sock, STDOUT_FILENO);
1388         mm_send_fd(sock, STDERR_FILENO);
1389
1390         /* Wait for reply, so master has a chance to gather ttymodes */
1391         buffer_clear(&m);
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         buffer_free(&m);
1397
1398         signal(SIGHUP, control_client_sighandler);
1399         signal(SIGINT, control_client_sighandler);
1400         signal(SIGTERM, control_client_sighandler);
1401         signal(SIGWINCH, control_client_sigrelay);
1402
1403         if (tty_flag)
1404                 enter_raw_mode();
1405
1406         /* Stick around until the controlee closes the client_fd */
1407         exitval = 0;
1408         for (;!control_client_terminate;) {
1409                 r = read(sock, &exitval, sizeof(exitval));
1410                 if (r == 0) {
1411                         debug2("Received EOF from master");
1412                         break;
1413                 }
1414                 if (r > 0)
1415                         debug2("Received exit status from master %d", exitval);
1416                 if (r == -1 && errno != EINTR)
1417                         fatal("%s: read %s", __func__, strerror(errno));
1418         }
1419
1420         if (control_client_terminate)
1421                 debug2("Exiting on signal %d", control_client_terminate);
1422
1423         close(sock);
1424
1425         leave_raw_mode();
1426
1427         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1428                 fprintf(stderr, "Connection to master closed.\r\n");
1429
1430         exit(exitval);
1431 }