crypto/openssh/ssh.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * Ssh client program.  This program can be used to log into a remote machine.
   6  * The software supports strong authentication, encryption, and forwarding
   7  * of X11, TCP/IP, and authentication connections.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  16  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  17  *
  18  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  19  * in Canada (German citizen).
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43 RCSID("$OpenBSD: ssh.c,v 1.249 2005/07/30 01:26:16 djm Exp $");
  44 RCSID("$FreeBSD$");
  45
  46 #include <openssl/evp.h>
  47 #include <openssl/err.h>
  48
  49 #include "ssh.h"
  50 #include "ssh1.h"
  51 #include "ssh2.h"
  52 #include "compat.h"
  53 #include "cipher.h"
  54 #include "xmalloc.h"
  55 #include "packet.h"
  56 #include "buffer.h"
  57 #include "bufaux.h"
  58 #include "channels.h"
  59 #include "key.h"
  60 #include "authfd.h"
  61 #include "authfile.h"
  62 #include "pathnames.h"
  63 #include "dispatch.h"
  64 #include "clientloop.h"
  65 #include "log.h"
  66 #include "readconf.h"
  67 #include "sshconnect.h"
  68 #include "misc.h"
  69 #include "kex.h"
  70 #include "mac.h"
  71 #include "sshpty.h"
  72 #include "match.h"
  73 #include "msg.h"
  74 #include "monitor_fdpass.h"
  75 #include "uidswap.h"
  76
  77 #ifdef SMARTCARD
  78 #include "scard.h"
  79 #endif
  80
  81 extern char *__progname;
  82
  83 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
  84 int debug_flag = 0;
  85
  86 /* Flag indicating whether a tty should be allocated */
  87 int tty_flag = 0;
  88 int no_tty_flag = 0;
  89 int force_tty_flag = 0;
  90
  91 /* don't exec a shell */
  92 int no_shell_flag = 0;
  93
  94 /*
  95  * Flag indicating that nothing should be read from stdin.  This can be set
  96  * on the command line.
  97  */
  98 int stdin_null_flag = 0;
  99
 100 /*
 101  * Flag indicating that ssh should fork after authentication.  This is useful
 102  * so that the passphrase can be entered manually, and then ssh goes to the
 103  * background.
 104  */
 105 int fork_after_authentication_flag = 0;
 106
 107 /*
 108  * General data structure for command line options and options configurable
 109  * in configuration files.  See readconf.h.
 110  */
 111 Options options;
 112
 113 /* optional user configfile */
 114 char *config = NULL;
 115
 116 /*
 117  * Name of the host we are connecting to.  This is the name given on the
 118  * command line, or the HostName specified for the user-supplied name in a
 119  * configuration file.
 120  */
 121 char *host;
 122
 123 /* socket address the host resolves to */
 124 struct sockaddr_storage hostaddr;
 125
 126 /* Private host keys. */
 127 Sensitive sensitive_data;
 128
 129 /* Original real UID. */
 130 uid_t original_real_uid;
 131 uid_t original_effective_uid;
 132
 133 /* command to be executed */
 134 Buffer command;
 135
 136 /* Should we execute a command or invoke a subsystem? */
 137 int subsystem_flag = 0;
 138
 139 /* # of replies received for global requests */
 140 static int client_global_request_id = 0;
 141
 142 /* pid of proxycommand child process */
 143 pid_t proxy_command_pid = 0;
 144
 145 /* fd to control socket */
 146 int control_fd = -1;
 147
 148 /* Multiplexing control command */
 149 static u_int mux_command = 0;
 150
 151 /* Only used in control client mode */
 152 volatile sig_atomic_t control_client_terminate = 0;
 153 u_int control_server_pid = 0;
 154
 155 /* Prints a help message to the user.  This function never returns. */
 156
 157 static void
 158 usage(void)
 159 {
 160         fprintf(stderr,
 161 "usage: ssh [-1246AaCfgkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 162 "           [-D port] [-e escape_char] [-F configfile]\n"
 163 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 164 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 165 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 166 "           [user@]hostname [command]\n"
 167         );
 168         exit(1);
 169 }
 170
 171 static int ssh_session(void);
 172 static int ssh_session2(void);
 173 static void load_public_identity_files(void);
 174 static void control_client(const char *path);
 175
 176 /*
 177  * Main program for the ssh client.
 178  */
 179 int
 180 main(int ac, char **av)
 181 {
 182         int i, opt, exit_status;
 183         char *p, *cp, *line, buf[256];
 184         struct stat st;
 185         struct passwd *pw;
 186         int dummy;
 187         extern int optind, optreset;
 188         extern char *optarg;
 189         struct servent *sp;
 190         Forward fwd;
 191
 192         __progname = ssh_get_progname(av[0]);
 193         init_rng();
 194
 195         /*
 196          * Save the original real uid.  It will be needed later (uid-swapping
 197          * may clobber the real uid).
 198          */
 199         original_real_uid = getuid();
 200         original_effective_uid = geteuid();
 201
 202         /*
 203          * Use uid-swapping to give up root privileges for the duration of
 204          * option processing.  We will re-instantiate the rights when we are
 205          * ready to create the privileged port, and will permanently drop
 206          * them when the port has been created (actually, when the connection
 207          * has been made, as we may need to create the port several times).
 208          */
 209         PRIV_END;
 210
 211 #ifdef HAVE_SETRLIMIT
 212         /* If we are installed setuid root be careful to not drop core. */
 213         if (original_real_uid != original_effective_uid) {
 214                 struct rlimit rlim;
 215                 rlim.rlim_cur = rlim.rlim_max = 0;
 216                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 217                         fatal("setrlimit failed: %.100s", strerror(errno));
 218         }
 219 #endif
 220         /* Get user data. */
 221         pw = getpwuid(original_real_uid);
 222         if (!pw) {
 223                 logit("You don't exist, go away!");
 224                 exit(1);
 225         }
 226         /* Take a copy of the returned structure. */
 227         pw = pwcopy(pw);
 228
 229         /*
 230          * Set our umask to something reasonable, as some files are created
 231          * with the default umask.  This will make them world-readable but
 232          * writable only by the owner, which is ok for all files for which we
 233          * don't set the modes explicitly.
 234          */
 235         umask(022);
 236
 237         /* Initialize option structure to indicate that no values have been set. */
 238         initialize_options(&options);
 239
 240         /* Parse command-line arguments. */
 241         host = NULL;
 242
 243 again:
 244         while ((opt = getopt(ac, av,
 245             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:MNO:PR:S:TVXY")) != -1) {
 246                 switch (opt) {
 247                 case '1':
 248                         options.protocol = SSH_PROTO_1;
 249                         break;
 250                 case '2':
 251                         options.protocol = SSH_PROTO_2;
 252                         break;
 253                 case '4':
 254                         options.address_family = AF_INET;
 255                         break;
 256                 case '6':
 257                         options.address_family = AF_INET6;
 258                         break;
 259                 case 'n':
 260                         stdin_null_flag = 1;
 261                         break;
 262                 case 'f':
 263                         fork_after_authentication_flag = 1;
 264                         stdin_null_flag = 1;
 265                         break;
 266                 case 'x':
 267                         options.forward_x11 = 0;
 268                         break;
 269                 case 'X':
 270                         options.forward_x11 = 1;
 271                         break;
 272                 case 'Y':
 273                         options.forward_x11 = 1;
 274                         options.forward_x11_trusted = 1;
 275                         break;
 276                 case 'g':
 277                         options.gateway_ports = 1;
 278                         break;
 279                 case 'O':
 280                         if (strcmp(optarg, "check") == 0)
 281                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 282                         else if (strcmp(optarg, "exit") == 0)
 283                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 284                         else
 285                                 fatal("Invalid multiplex command.");
 286                         break;
 287                 case 'P':       /* deprecated */
 288                         options.use_privileged_port = 0;
 289                         break;
 290                 case 'a':
 291                         options.forward_agent = 0;
 292                         break;
 293                 case 'A':
 294                         options.forward_agent = 1;
 295                         break;
 296                 case 'k':
 297                         options.gss_deleg_creds = 0;
 298                         break;
 299                 case 'i':
 300                         if (stat(optarg, &st) < 0) {
 301                                 fprintf(stderr, "Warning: Identity file %s "
 302                                     "not accessible: %s.\n", optarg,
 303                                     strerror(errno));
 304                                 break;
 305                         }
 306                         if (options.num_identity_files >=
 307                             SSH_MAX_IDENTITY_FILES)
 308                                 fatal("Too many identity files specified "
 309                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 310                         options.identity_files[options.num_identity_files++] =
 311                             xstrdup(optarg);
 312                         break;
 313                 case 'I':
 314 #ifdef SMARTCARD
 315                         options.smartcard_device = xstrdup(optarg);
 316 #else
 317                         fprintf(stderr, "no support for smartcards.\n");
 318 #endif
 319                         break;
 320                 case 't':
 321                         if (tty_flag)
 322                                 force_tty_flag = 1;
 323                         tty_flag = 1;
 324                         break;
 325                 case 'v':
 326                         if (debug_flag == 0) {
 327                                 debug_flag = 1;
 328                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 329                         } else {
 330                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 331                                         options.log_level++;
 332                                 break;
 333                         }
 334                         /* FALLTHROUGH */
 335                 case 'V':
 336                         fprintf(stderr, "%s, %s\n",
 337                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 338                         if (opt == 'V')
 339                                 exit(0);
 340                         break;
 341                 case 'q':
 342                         options.log_level = SYSLOG_LEVEL_QUIET;
 343                         break;
 344                 case 'e':
 345                         if (optarg[0] == '^' && optarg[2] == 0 &&
 346                             (u_char) optarg[1] >= 64 &&
 347                             (u_char) optarg[1] < 128)
 348                                 options.escape_char = (u_char) optarg[1] & 31;
 349                         else if (strlen(optarg) == 1)
 350                                 options.escape_char = (u_char) optarg[0];
 351                         else if (strcmp(optarg, "none") == 0)
 352                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 353                         else {
 354                                 fprintf(stderr, "Bad escape character '%s'.\n",
 355                                     optarg);
 356                                 exit(1);
 357                         }
 358                         break;
 359                 case 'c':
 360                         if (ciphers_valid(optarg)) {
 361                                 /* SSH2 only */
 362                                 options.ciphers = xstrdup(optarg);
 363                                 options.cipher = SSH_CIPHER_INVALID;
 364                         } else {
 365                                 /* SSH1 only */
 366                                 options.cipher = cipher_number(optarg);
 367                                 if (options.cipher == -1) {
 368                                         fprintf(stderr,
 369                                             "Unknown cipher type '%s'\n",
 370                                             optarg);
 371                                         exit(1);
 372                                 }
 373                                 if (options.cipher == SSH_CIPHER_3DES)
 374                                         options.ciphers = "3des-cbc";
 375                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 376                                         options.ciphers = "blowfish-cbc";
 377                                 else
 378                                         options.ciphers = (char *)-1;
 379                         }
 380                         break;
 381                 case 'm':
 382                         if (mac_valid(optarg))
 383                                 options.macs = xstrdup(optarg);
 384                         else {
 385                                 fprintf(stderr, "Unknown mac type '%s'\n",
 386                                     optarg);
 387                                 exit(1);
 388                         }
 389                         break;
 390                 case 'M':
 391                         if (options.control_master == SSHCTL_MASTER_YES)
 392                                 options.control_master = SSHCTL_MASTER_ASK;
 393                         else
 394                                 options.control_master = SSHCTL_MASTER_YES;
 395                         break;
 396                 case 'p':
 397                         options.port = a2port(optarg);
 398                         if (options.port == 0) {
 399                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 400                                 exit(1);
 401                         }
 402                         break;
 403                 case 'l':
 404                         options.user = optarg;
 405                         break;
 406
 407                 case 'L':
 408                         if (parse_forward(&fwd, optarg))
 409                                 add_local_forward(&options, &fwd);
 410                         else {
 411                                 fprintf(stderr,
 412                                     "Bad local forwarding specification '%s'\n",
 413                                     optarg);
 414                                 exit(1);
 415                         }
 416                         break;
 417
 418                 case 'R':
 419                         if (parse_forward(&fwd, optarg)) {
 420                                 add_remote_forward(&options, &fwd);
 421                         } else {
 422                                 fprintf(stderr,
 423                                     "Bad remote forwarding specification "
 424                                     "'%s'\n", optarg);
 425                                 exit(1);
 426                         }
 427                         break;
 428
 429                 case 'D':
 430                         cp = p = xstrdup(optarg);
 431                         memset(&fwd, '\0', sizeof(fwd));
 432                         fwd.connect_host = "socks";
 433                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 434                                 fprintf(stderr, "Bad dynamic forwarding "
 435                                     "specification '%.100s'\n", optarg);
 436                                 exit(1);
 437                         }
 438                         if (cp != NULL) {
 439                                 fwd.listen_port = a2port(cp);
 440                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 441                         } else {
 442                                 fwd.listen_port = a2port(fwd.listen_host);
 443                                 fwd.listen_host = NULL;
 444                         }
 445
 446                         if (fwd.listen_port == 0) {
 447                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 448                                     optarg);
 449                                 exit(1);
 450                         }
 451                         add_local_forward(&options, &fwd);
 452                         xfree(p);
 453                         break;
 454
 455                 case 'C':
 456                         options.compression = 1;
 457                         break;
 458                 case 'N':
 459                         no_shell_flag = 1;
 460                         no_tty_flag = 1;
 461                         break;
 462                 case 'T':
 463                         no_tty_flag = 1;
 464                         break;
 465                 case 'o':
 466                         dummy = 1;
 467                         line = xstrdup(optarg);
 468                         if (process_config_line(&options, host ? host : "",
 469                             line, "command-line", 0, &dummy) != 0)
 470                                 exit(1);
 471                         xfree(line);
 472                         break;
 473                 case 's':
 474                         subsystem_flag = 1;
 475                         break;
 476                 case 'S':
 477                         if (options.control_path != NULL)
 478                                 free(options.control_path);
 479                         options.control_path = xstrdup(optarg);
 480                         break;
 481                 case 'b':
 482                         options.bind_address = optarg;
 483                         break;
 484                 case 'F':
 485                         config = optarg;
 486                         break;
 487                 default:
 488                         usage();
 489                 }
 490         }
 491
 492         ac -= optind;
 493         av += optind;
 494
 495         if (ac > 0 && !host && **av != '-') {
 496                 if (strrchr(*av, '@')) {
 497                         p = xstrdup(*av);
 498                         cp = strrchr(p, '@');
 499                         if (cp == NULL || cp == p)
 500                                 usage();
 501                         options.user = p;
 502                         *cp = '\0';
 503                         host = ++cp;
 504                 } else
 505                         host = *av;
 506                 if (ac > 1) {
 507                         optind = optreset = 1;
 508                         goto again;
 509                 }
 510                 ac--, av++;
 511         }
 512
 513         /* Check that we got a host name. */
 514         if (!host)
 515                 usage();
 516
 517         SSLeay_add_all_algorithms();
 518         ERR_load_crypto_strings();
 519
 520         /* Initialize the command to execute on remote host. */
 521         buffer_init(&command);
 522
 523         /*
 524          * Save the command to execute on the remote host in a buffer. There
 525          * is no limit on the length of the command, except by the maximum
 526          * packet size.  Also sets the tty flag if there is no command.
 527          */
 528         if (!ac) {
 529                 /* No command specified - execute shell on a tty. */
 530                 tty_flag = 1;
 531                 if (subsystem_flag) {
 532                         fprintf(stderr,
 533                             "You must specify a subsystem to invoke.\n");
 534                         usage();
 535                 }
 536         } else {
 537                 /* A command has been specified.  Store it into the buffer. */
 538                 for (i = 0; i < ac; i++) {
 539                         if (i)
 540                                 buffer_append(&command, " ", 1);
 541                         buffer_append(&command, av[i], strlen(av[i]));
 542                 }
 543         }
 544
 545         /* Cannot fork to background if no command. */
 546         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 547                 fatal("Cannot fork into background without a command to execute.");
 548
 549         /* Allocate a tty by default if no command specified. */
 550         if (buffer_len(&command) == 0)
 551                 tty_flag = 1;
 552
 553         /* Force no tty */
 554         if (no_tty_flag)
 555                 tty_flag = 0;
 556         /* Do not allocate a tty if stdin is not a tty. */
 557         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 558                 if (tty_flag)
 559                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 560                 tty_flag = 0;
 561         }
 562
 563         /*
 564          * Initialize "log" output.  Since we are the client all output
 565          * actually goes to stderr.
 566          */
 567         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 568             SYSLOG_FACILITY_USER, 1);
 569
 570         /*
 571          * Read per-user configuration file.  Ignore the system wide config
 572          * file if the user specifies a config file on the command line.
 573          */
 574         if (config != NULL) {
 575                 if (!read_config_file(config, host, &options, 0))
 576                         fatal("Can't open user config file %.100s: "
 577                             "%.100s", config, strerror(errno));
 578         } else  {
 579                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 580                     _PATH_SSH_USER_CONFFILE);
 581                 (void)read_config_file(buf, host, &options, 1);
 582
 583                 /* Read systemwide configuration file after use config. */
 584                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 585                     &options, 0);
 586         }
 587
 588         /* Fill configuration defaults. */
 589         fill_default_options(&options);
 590
 591         channel_set_af(options.address_family);
 592
 593         /* reinit */
 594         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 595
 596         seed_rng();
 597
 598         if (options.user == NULL)
 599                 options.user = xstrdup(pw->pw_name);
 600
 601         if (options.hostname != NULL)
 602                 host = options.hostname;
 603
 604         /* Find canonic host name. */
 605         if (strchr(host, '.') == 0) {
 606                 struct addrinfo hints;
 607                 struct addrinfo *ai = NULL;
 608                 int errgai;
 609                 memset(&hints, 0, sizeof(hints));
 610                 hints.ai_family = options.address_family;
 611                 hints.ai_flags = AI_CANONNAME;
 612                 hints.ai_socktype = SOCK_STREAM;
 613                 errgai = getaddrinfo(host, NULL, &hints, &ai);
 614                 if (errgai == 0) {
 615                         if (ai->ai_canonname != NULL)
 616                                 host = xstrdup(ai->ai_canonname);
 617                         freeaddrinfo(ai);
 618                 }
 619         }
 620
 621         /* force lowercase for hostkey matching */
 622         if (options.host_key_alias != NULL) {
 623                 for (p = options.host_key_alias; *p; p++)
 624                         if (isupper(*p))
 625                                 *p = tolower(*p);
 626         }
 627
 628         /* Get default port if port has not been set. */
 629         if (options.port == 0) {
 630                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 631                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 632         }
 633
 634         if (options.proxy_command != NULL &&
 635             strcmp(options.proxy_command, "none") == 0)
 636                 options.proxy_command = NULL;
 637         if (options.control_path != NULL &&
 638             strcmp(options.control_path, "none") == 0)
 639                 options.control_path = NULL;
 640
 641         if (options.control_path != NULL) {
 642                 snprintf(buf, sizeof(buf), "%d", options.port);
 643                 cp = tilde_expand_filename(options.control_path,
 644                     original_real_uid);
 645                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 646                     "r", options.user, (char *)NULL);
 647                 xfree(cp);
 648         }
 649         if (mux_command != 0 && options.control_path == NULL)
 650                 fatal("No ControlPath specified for \"-O\" command");
 651         if (options.control_path != NULL)
 652                 control_client(options.control_path);
 653
 654         /* Open a connection to the remote host. */
 655         if (ssh_connect(host, &hostaddr, options.port,
 656             options.address_family, options.connection_attempts,
 657 #ifdef HAVE_CYGWIN
 658             options.use_privileged_port,
 659 #else
 660             original_effective_uid == 0 && options.use_privileged_port,
 661 #endif
 662             options.proxy_command) != 0)
 663                 exit(1);
 664
 665         /*
 666          * If we successfully made the connection, load the host private key
 667          * in case we will need it later for combined rsa-rhosts
 668          * authentication. This must be done before releasing extra
 669          * privileges, because the file is only readable by root.
 670          * If we cannot access the private keys, load the public keys
 671          * instead and try to execute the ssh-keysign helper instead.
 672          */
 673         sensitive_data.nkeys = 0;
 674         sensitive_data.keys = NULL;
 675         sensitive_data.external_keysign = 0;
 676         if (options.rhosts_rsa_authentication ||
 677             options.hostbased_authentication) {
 678                 sensitive_data.nkeys = 3;
 679                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 680                     sizeof(Key));
 681
 682                 PRIV_START;
 683                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 684                     _PATH_HOST_KEY_FILE, "", NULL);
 685                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 686                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 687                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 688                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 689                 PRIV_END;
 690
 691                 if (options.hostbased_authentication == 1 &&
 692                     sensitive_data.keys[0] == NULL &&
 693                     sensitive_data.keys[1] == NULL &&
 694                     sensitive_data.keys[2] == NULL) {
 695                         sensitive_data.keys[1] = key_load_public(
 696                             _PATH_HOST_DSA_KEY_FILE, NULL);
 697                         sensitive_data.keys[2] = key_load_public(
 698                             _PATH_HOST_RSA_KEY_FILE, NULL);
 699                         sensitive_data.external_keysign = 1;
 700                 }
 701         }
 702         /*
 703          * Get rid of any extra privileges that we may have.  We will no
 704          * longer need them.  Also, extra privileges could make it very hard
 705          * to read identity files and other non-world-readable files from the
 706          * user's home directory if it happens to be on a NFS volume where
 707          * root is mapped to nobody.
 708          */
 709         if (original_effective_uid == 0) {
 710                 PRIV_START;
 711                 permanently_set_uid(pw);
 712         }
 713
 714         /*
 715          * Now that we are back to our own permissions, create ~/.ssh
 716          * directory if it doesn\'t already exist.
 717          */
 718         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 719         if (stat(buf, &st) < 0)
 720                 if (mkdir(buf, 0700) < 0)
 721                         error("Could not create directory '%.200s'.", buf);
 722
 723         /* load options.identity_files */
 724         load_public_identity_files();
 725
 726         /* Expand ~ in known host file names. */
 727         /* XXX mem-leaks: */
 728         options.system_hostfile =
 729             tilde_expand_filename(options.system_hostfile, original_real_uid);
 730         options.user_hostfile =
 731             tilde_expand_filename(options.user_hostfile, original_real_uid);
 732         options.system_hostfile2 =
 733             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 734         options.user_hostfile2 =
 735             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 736
 737         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 738
 739         /* Log into the remote system.  This never returns if the login fails. */
 740         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 741
 742         /* We no longer need the private host keys.  Clear them now. */
 743         if (sensitive_data.nkeys != 0) {
 744                 for (i = 0; i < sensitive_data.nkeys; i++) {
 745                         if (sensitive_data.keys[i] != NULL) {
 746                                 /* Destroys contents safely */
 747                                 debug3("clear hostkey %d", i);
 748                                 key_free(sensitive_data.keys[i]);
 749                                 sensitive_data.keys[i] = NULL;
 750                         }
 751                 }
 752                 xfree(sensitive_data.keys);
 753         }
 754         for (i = 0; i < options.num_identity_files; i++) {
 755                 if (options.identity_files[i]) {
 756                         xfree(options.identity_files[i]);
 757                         options.identity_files[i] = NULL;
 758                 }
 759                 if (options.identity_keys[i]) {
 760                         key_free(options.identity_keys[i]);
 761                         options.identity_keys[i] = NULL;
 762                 }
 763         }
 764
 765         exit_status = compat20 ? ssh_session2() : ssh_session();
 766         packet_close();
 767
 768         if (options.control_path != NULL && control_fd != -1)
 769                 unlink(options.control_path);
 770
 771         /*
 772          * Send SIGHUP to proxy command if used. We don't wait() in
 773          * case it hangs and instead rely on init to reap the child
 774          */
 775         if (proxy_command_pid > 1)
 776                 kill(proxy_command_pid, SIGHUP);
 777
 778         return exit_status;
 779 }
 780
 781 static void
 782 ssh_init_forwarding(void)
 783 {
 784         int success = 0;
 785         int i;
 786
 787         /* Initiate local TCP/IP port forwardings. */
 788         for (i = 0; i < options.num_local_forwards; i++) {
 789                 debug("Local connections to %.200s:%d forwarded to remote "
 790                     "address %.200s:%d",
 791                     (options.local_forwards[i].listen_host == NULL) ?
 792                     (options.gateway_ports ? "*" : "LOCALHOST") :
 793                     options.local_forwards[i].listen_host,
 794                     options.local_forwards[i].listen_port,
 795                     options.local_forwards[i].connect_host,
 796                     options.local_forwards[i].connect_port);
 797                 success += channel_setup_local_fwd_listener(
 798                     options.local_forwards[i].listen_host,
 799                     options.local_forwards[i].listen_port,
 800                     options.local_forwards[i].connect_host,
 801                     options.local_forwards[i].connect_port,
 802                     options.gateway_ports);
 803         }
 804         if (i > 0 && success == 0)
 805                 error("Could not request local forwarding.");
 806
 807         /* Initiate remote TCP/IP port forwardings. */
 808         for (i = 0; i < options.num_remote_forwards; i++) {
 809                 debug("Remote connections from %.200s:%d forwarded to "
 810                     "local address %.200s:%d",
 811                     (options.remote_forwards[i].listen_host == NULL) ?
 812                     (options.gateway_ports ? "*" : "LOCALHOST") :
 813                     options.remote_forwards[i].listen_host,
 814                     options.remote_forwards[i].listen_port,
 815                     options.remote_forwards[i].connect_host,
 816                     options.remote_forwards[i].connect_port);
 817                 channel_request_remote_forwarding(
 818                     options.remote_forwards[i].listen_host,
 819                     options.remote_forwards[i].listen_port,
 820                     options.remote_forwards[i].connect_host,
 821                     options.remote_forwards[i].connect_port);
 822         }
 823 }
 824
 825 static void
 826 check_agent_present(void)
 827 {
 828         if (options.forward_agent) {
 829                 /* Clear agent forwarding if we don\'t have an agent. */
 830                 if (!ssh_agent_present())
 831                         options.forward_agent = 0;
 832         }
 833 }
 834
 835 static int
 836 ssh_session(void)
 837 {
 838         int type;
 839         int interactive = 0;
 840         int have_tty = 0;
 841         struct winsize ws;
 842         char *cp;
 843         const char *display;
 844
 845         /* Enable compression if requested. */
 846         if (options.compression) {
 847                 debug("Requesting compression at level %d.", options.compression_level);
 848
 849                 if (options.compression_level < 1 || options.compression_level > 9)
 850                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 851
 852                 /* Send the request. */
 853                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 854                 packet_put_int(options.compression_level);
 855                 packet_send();
 856                 packet_write_wait();
 857                 type = packet_read();
 858                 if (type == SSH_SMSG_SUCCESS)
 859                         packet_start_compression(options.compression_level);
 860                 else if (type == SSH_SMSG_FAILURE)
 861                         logit("Warning: Remote host refused compression.");
 862                 else
 863                         packet_disconnect("Protocol error waiting for compression response.");
 864         }
 865         /* Allocate a pseudo tty if appropriate. */
 866         if (tty_flag) {
 867                 debug("Requesting pty.");
 868
 869                 /* Start the packet. */
 870                 packet_start(SSH_CMSG_REQUEST_PTY);
 871
 872                 /* Store TERM in the packet.  There is no limit on the
 873                    length of the string. */
 874                 cp = getenv("TERM");
 875                 if (!cp)
 876                         cp = "";
 877                 packet_put_cstring(cp);
 878
 879                 /* Store window size in the packet. */
 880                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 881                         memset(&ws, 0, sizeof(ws));
 882                 packet_put_int(ws.ws_row);
 883                 packet_put_int(ws.ws_col);
 884                 packet_put_int(ws.ws_xpixel);
 885                 packet_put_int(ws.ws_ypixel);
 886
 887                 /* Store tty modes in the packet. */
 888                 tty_make_modes(fileno(stdin), NULL);
 889
 890                 /* Send the packet, and wait for it to leave. */
 891                 packet_send();
 892                 packet_write_wait();
 893
 894                 /* Read response from the server. */
 895                 type = packet_read();
 896                 if (type == SSH_SMSG_SUCCESS) {
 897                         interactive = 1;
 898                         have_tty = 1;
 899                 } else if (type == SSH_SMSG_FAILURE)
 900                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 901                 else
 902                         packet_disconnect("Protocol error waiting for pty request response.");
 903         }
 904         /* Request X11 forwarding if enabled and DISPLAY is set. */
 905         display = getenv("DISPLAY");
 906         if (options.forward_x11 && display != NULL) {
 907                 char *proto, *data;
 908                 /* Get reasonable local authentication information. */
 909                 client_x11_get_proto(display, options.xauth_location,
 910                     options.forward_x11_trusted, &proto, &data);
 911                 /* Request forwarding with authentication spoofing. */
 912                 debug("Requesting X11 forwarding with authentication spoofing.");
 913                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 914
 915                 /* Read response from the server. */
 916                 type = packet_read();
 917                 if (type == SSH_SMSG_SUCCESS) {
 918                         interactive = 1;
 919                 } else if (type == SSH_SMSG_FAILURE) {
 920                         logit("Warning: Remote host denied X11 forwarding.");
 921                 } else {
 922                         packet_disconnect("Protocol error waiting for X11 forwarding");
 923                 }
 924         }
 925         /* Tell the packet module whether this is an interactive session. */
 926         packet_set_interactive(interactive);
 927
 928         /* Request authentication agent forwarding if appropriate. */
 929         check_agent_present();
 930
 931         if (options.forward_agent) {
 932                 debug("Requesting authentication agent forwarding.");
 933                 auth_request_forwarding();
 934
 935                 /* Read response from the server. */
 936                 type = packet_read();
 937                 packet_check_eom();
 938                 if (type != SSH_SMSG_SUCCESS)
 939                         logit("Warning: Remote host denied authentication agent forwarding.");
 940         }
 941
 942         /* Initiate port forwardings. */
 943         ssh_init_forwarding();
 944
 945         /* If requested, let ssh continue in the background. */
 946         if (fork_after_authentication_flag)
 947                 if (daemon(1, 1) < 0)
 948                         fatal("daemon() failed: %.200s", strerror(errno));
 949
 950         /*
 951          * If a command was specified on the command line, execute the
 952          * command now. Otherwise request the server to start a shell.
 953          */
 954         if (buffer_len(&command) > 0) {
 955                 int len = buffer_len(&command);
 956                 if (len > 900)
 957                         len = 900;
 958                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 959                 packet_start(SSH_CMSG_EXEC_CMD);
 960                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 961                 packet_send();
 962                 packet_write_wait();
 963         } else {
 964                 debug("Requesting shell.");
 965                 packet_start(SSH_CMSG_EXEC_SHELL);
 966                 packet_send();
 967                 packet_write_wait();
 968         }
 969
 970         /* Enter the interactive session. */
 971         return client_loop(have_tty, tty_flag ?
 972             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
 973 }
 974
 975 static void
 976 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
 977 {
 978         int id, len;
 979
 980         id = packet_get_int();
 981         len = buffer_len(&command);
 982         if (len > 900)
 983                 len = 900;
 984         packet_check_eom();
 985         if (type == SSH2_MSG_CHANNEL_FAILURE)
 986                 fatal("Request for subsystem '%.*s' failed on channel %d",
 987                     len, (u_char *)buffer_ptr(&command), id);
 988 }
 989
 990 void
 991 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
 992 {
 993         int i;
 994
 995         i = client_global_request_id++;
 996         if (i >= options.num_remote_forwards)
 997                 return;
 998         debug("remote forward %s for: listen %d, connect %s:%d",
 999             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1000             options.remote_forwards[i].listen_port,
1001             options.remote_forwards[i].connect_host,
1002             options.remote_forwards[i].connect_port);
1003         if (type == SSH2_MSG_REQUEST_FAILURE)
1004                 logit("Warning: remote port forwarding failed for listen "
1005                     "port %d", options.remote_forwards[i].listen_port);
1006 }
1007
1008 static void
1009 ssh_control_listener(void)
1010 {
1011         struct sockaddr_un addr;
1012         mode_t old_umask;
1013         int addr_len;
1014
1015         if (options.control_path == NULL ||
1016             options.control_master == SSHCTL_MASTER_NO)
1017                 return;
1018
1019         debug("setting up multiplex master socket");
1020
1021         memset(&addr, '\0', sizeof(addr));
1022         addr.sun_family = AF_UNIX;
1023         addr_len = offsetof(struct sockaddr_un, sun_path) +
1024             strlen(options.control_path) + 1;
1025
1026         if (strlcpy(addr.sun_path, options.control_path,
1027             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1028                 fatal("ControlPath too long");
1029
1030         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1031                 fatal("%s socket(): %s\n", __func__, strerror(errno));
1032
1033         old_umask = umask(0177);
1034         if (bind(control_fd, (struct sockaddr*)&addr, addr_len) == -1) {
1035                 control_fd = -1;
1036                 if (errno == EINVAL || errno == EADDRINUSE)
1037                         fatal("ControlSocket %s already exists",
1038                             options.control_path);
1039                 else
1040                         fatal("%s bind(): %s\n", __func__, strerror(errno));
1041         }
1042         umask(old_umask);
1043
1044         if (listen(control_fd, 64) == -1)
1045                 fatal("%s listen(): %s\n", __func__, strerror(errno));
1046
1047         set_nonblock(control_fd);
1048 }
1049
1050 /* request pty/x11/agent/tcpfwd/shell for channel */
1051 static void
1052 ssh_session2_setup(int id, void *arg)
1053 {
1054         extern char **environ;
1055         const char *display;
1056         int interactive = tty_flag;
1057
1058         display = getenv("DISPLAY");
1059         if (options.forward_x11 && display != NULL) {
1060                 char *proto, *data;
1061                 /* Get reasonable local authentication information. */
1062                 client_x11_get_proto(display, options.xauth_location,
1063                     options.forward_x11_trusted, &proto, &data);
1064                 /* Request forwarding with authentication spoofing. */
1065                 debug("Requesting X11 forwarding with authentication spoofing.");
1066                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1067                 interactive = 1;
1068                 /* XXX wait for reply */
1069         }
1070
1071         check_agent_present();
1072         if (options.forward_agent) {
1073                 debug("Requesting authentication agent forwarding.");
1074                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1075                 packet_send();
1076         }
1077
1078         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1079             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1080
1081         packet_set_interactive(interactive);
1082 }
1083
1084 /* open new channel for a session */
1085 static int
1086 ssh_session2_open(void)
1087 {
1088         Channel *c;
1089         int window, packetmax, in, out, err;
1090
1091         if (stdin_null_flag) {
1092                 in = open(_PATH_DEVNULL, O_RDONLY);
1093         } else {
1094                 in = dup(STDIN_FILENO);
1095         }
1096         out = dup(STDOUT_FILENO);
1097         err = dup(STDERR_FILENO);
1098
1099         if (in < 0 || out < 0 || err < 0)
1100                 fatal("dup() in/out/err failed");
1101
1102         /* enable nonblocking unless tty */
1103         if (!isatty(in))
1104                 set_nonblock(in);
1105         if (!isatty(out))
1106                 set_nonblock(out);
1107         if (!isatty(err))
1108                 set_nonblock(err);
1109
1110         window = CHAN_SES_WINDOW_DEFAULT;
1111         packetmax = CHAN_SES_PACKET_DEFAULT;
1112         if (tty_flag) {
1113                 window >>= 1;
1114                 packetmax >>= 1;
1115         }
1116         c = channel_new(
1117             "session", SSH_CHANNEL_OPENING, in, out, err,
1118             window, packetmax, CHAN_EXTENDED_WRITE,
1119             "client-session", /*nonblock*/0);
1120
1121         debug3("ssh_session2_open: channel_new: %d", c->self);
1122
1123         channel_send_open(c->self);
1124         if (!no_shell_flag)
1125                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1126
1127         return c->self;
1128 }
1129
1130 static int
1131 ssh_session2(void)
1132 {
1133         int id = -1;
1134
1135         /* XXX should be pre-session */
1136         ssh_init_forwarding();
1137         ssh_control_listener();
1138
1139         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1140                 id = ssh_session2_open();
1141
1142         /* If requested, let ssh continue in the background. */
1143         if (fork_after_authentication_flag)
1144                 if (daemon(1, 1) < 0)
1145                         fatal("daemon() failed: %.200s", strerror(errno));
1146
1147         return client_loop(tty_flag, tty_flag ?
1148             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1149 }
1150
1151 static void
1152 load_public_identity_files(void)
1153 {
1154         char *filename;
1155         int i = 0;
1156         Key *public;
1157 #ifdef SMARTCARD
1158         Key **keys;
1159
1160         if (options.smartcard_device != NULL &&
1161             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1162             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1163                 int count = 0;
1164                 for (i = 0; keys[i] != NULL; i++) {
1165                         count++;
1166                         memmove(&options.identity_files[1], &options.identity_files[0],
1167                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1168                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1169                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1170                         options.num_identity_files++;
1171                         options.identity_keys[0] = keys[i];
1172                         options.identity_files[0] = sc_get_key_label(keys[i]);
1173                 }
1174                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1175                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1176                 i = count;
1177                 xfree(keys);
1178         }
1179 #endif /* SMARTCARD */
1180         for (; i < options.num_identity_files; i++) {
1181                 filename = tilde_expand_filename(options.identity_files[i],
1182                     original_real_uid);
1183                 public = key_load_public(filename, NULL);
1184                 debug("identity file %s type %d", filename,
1185                     public ? public->type : -1);
1186                 xfree(options.identity_files[i]);
1187                 options.identity_files[i] = filename;
1188                 options.identity_keys[i] = public;
1189         }
1190 }
1191
1192 static void
1193 control_client_sighandler(int signo)
1194 {
1195         control_client_terminate = signo;
1196 }
1197
1198 static void
1199 control_client_sigrelay(int signo)
1200 {
1201         if (control_server_pid > 1)
1202                 kill(control_server_pid, signo);
1203 }
1204
1205 static int
1206 env_permitted(char *env)
1207 {
1208         int i;
1209         char name[1024], *cp;
1210
1211         strlcpy(name, env, sizeof(name));
1212         if ((cp = strchr(name, '=')) == NULL)
1213                 return (0);
1214
1215         *cp = '\0';
1216
1217         for (i = 0; i < options.num_send_env; i++)
1218                 if (match_pattern(name, options.send_env[i]))
1219                         return (1);
1220
1221         return (0);
1222 }
1223
1224 static void
1225 control_client(const char *path)
1226 {
1227         struct sockaddr_un addr;
1228         int i, r, fd, sock, exitval, num_env, addr_len;
1229         Buffer m;
1230         char *term;
1231         extern char **environ;
1232         u_int  flags;
1233
1234         if (mux_command == 0)
1235                 mux_command = SSHMUX_COMMAND_OPEN;
1236
1237         switch (options.control_master) {
1238         case SSHCTL_MASTER_AUTO:
1239         case SSHCTL_MASTER_AUTO_ASK:
1240                 debug("auto-mux: Trying existing master");
1241                 /* FALLTHROUGH */
1242         case SSHCTL_MASTER_NO:
1243                 break;
1244         default:
1245                 return;
1246         }
1247
1248         memset(&addr, '\0', sizeof(addr));
1249         addr.sun_family = AF_UNIX;
1250         addr_len = offsetof(struct sockaddr_un, sun_path) +
1251             strlen(path) + 1;
1252
1253         if (strlcpy(addr.sun_path, path,
1254             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1255                 fatal("ControlPath too long");
1256
1257         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1258                 fatal("%s socket(): %s", __func__, strerror(errno));
1259
1260         if (connect(sock, (struct sockaddr*)&addr, addr_len) == -1) {
1261                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1262                         fatal("Control socket connect(%.100s): %s", path,
1263                             strerror(errno));
1264                 }
1265                 if (errno == ENOENT)
1266                         debug("Control socket \"%.100s\" does not exist", path);
1267                 else {
1268                         error("Control socket connect(%.100s): %s", path,
1269                             strerror(errno));
1270                 }
1271                 close(sock);
1272                 return;
1273         }
1274
1275         if (stdin_null_flag) {
1276                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1277                         fatal("open(/dev/null): %s", strerror(errno));
1278                 if (dup2(fd, STDIN_FILENO) == -1)
1279                         fatal("dup2: %s", strerror(errno));
1280                 if (fd > STDERR_FILENO)
1281                         close(fd);
1282         }
1283
1284         term = getenv("TERM");
1285
1286         flags = 0;
1287         if (tty_flag)
1288                 flags |= SSHMUX_FLAG_TTY;
1289         if (subsystem_flag)
1290                 flags |= SSHMUX_FLAG_SUBSYS;
1291         if (options.forward_x11)
1292                 flags |= SSHMUX_FLAG_X11_FWD;
1293         if (options.forward_agent)
1294                 flags |= SSHMUX_FLAG_AGENT_FWD;
1295
1296         buffer_init(&m);
1297
1298         /* Send our command to server */
1299         buffer_put_int(&m, mux_command);
1300         buffer_put_int(&m, flags);
1301         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1302                 fatal("%s: msg_send", __func__);
1303         buffer_clear(&m);
1304
1305         /* Get authorisation status and PID of controlee */
1306         if (ssh_msg_recv(sock, &m) == -1)
1307                 fatal("%s: msg_recv", __func__);
1308         if (buffer_get_char(&m) != SSHMUX_VER)
1309                 fatal("%s: wrong version", __func__);
1310         if (buffer_get_int(&m) != 1)
1311                 fatal("Connection to master denied");
1312         control_server_pid = buffer_get_int(&m);
1313
1314         buffer_clear(&m);
1315
1316         switch (mux_command) {
1317         case SSHMUX_COMMAND_ALIVE_CHECK:
1318                 fprintf(stderr, "Master running (pid=%d)\r\n",
1319                     control_server_pid);
1320                 exit(0);
1321         case SSHMUX_COMMAND_TERMINATE:
1322                 fprintf(stderr, "Exit request sent.\r\n");
1323                 exit(0);
1324         case SSHMUX_COMMAND_OPEN:
1325                 /* continue below */
1326                 break;
1327         default:
1328                 fatal("silly mux_command %d", mux_command);
1329         }
1330
1331         /* SSHMUX_COMMAND_OPEN */
1332         buffer_put_cstring(&m, term ? term : "");
1333         buffer_append(&command, "\0", 1);
1334         buffer_put_cstring(&m, buffer_ptr(&command));
1335
1336         if (options.num_send_env == 0 || environ == NULL) {
1337                 buffer_put_int(&m, 0);
1338         } else {
1339                 /* Pass environment */
1340                 num_env = 0;
1341                 for (i = 0; environ[i] != NULL; i++)
1342                         if (env_permitted(environ[i]))
1343                                 num_env++; /* Count */
1344
1345                 buffer_put_int(&m, num_env);
1346
1347                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1348                         if (env_permitted(environ[i])) {
1349                                 num_env--;
1350                                 buffer_put_cstring(&m, environ[i]);
1351                         }
1352         }
1353
1354         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1355                 fatal("%s: msg_send", __func__);
1356
1357         mm_send_fd(sock, STDIN_FILENO);
1358         mm_send_fd(sock, STDOUT_FILENO);
1359         mm_send_fd(sock, STDERR_FILENO);
1360
1361         /* Wait for reply, so master has a chance to gather ttymodes */
1362         buffer_clear(&m);
1363         if (ssh_msg_recv(sock, &m) == -1)
1364                 fatal("%s: msg_recv", __func__);
1365         if (buffer_get_char(&m) != SSHMUX_VER)
1366                 fatal("%s: wrong version", __func__);
1367         buffer_free(&m);
1368
1369         signal(SIGHUP, control_client_sighandler);
1370         signal(SIGINT, control_client_sighandler);
1371         signal(SIGTERM, control_client_sighandler);
1372         signal(SIGWINCH, control_client_sigrelay);
1373
1374         if (tty_flag)
1375                 enter_raw_mode();
1376
1377         /* Stick around until the controlee closes the client_fd */
1378         exitval = 0;
1379         for (;!control_client_terminate;) {
1380                 r = read(sock, &exitval, sizeof(exitval));
1381                 if (r == 0) {
1382                         debug2("Received EOF from master");
1383                         break;
1384                 }
1385                 if (r > 0)
1386                         debug2("Received exit status from master %d", exitval);
1387                 if (r == -1 && errno != EINTR)
1388                         fatal("%s: read %s", __func__, strerror(errno));
1389         }
1390
1391         if (control_client_terminate)
1392                 debug2("Exiting on signal %d", control_client_terminate);
1393
1394         close(sock);
1395
1396         leave_raw_mode();
1397
1398         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1399                 fprintf(stderr, "Connection to master closed.\r\n");
1400
1401         exit(exitval);
1402 }