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 1.231 2005/02/16 09:56:44 otto Exp $");
  44
  45 #include <openssl/evp.h>
  46 #include <openssl/err.h>
  47
  48 #include "ssh.h"
  49 #include "ssh1.h"
  50 #include "ssh2.h"
  51 #include "compat.h"
  52 #include "cipher.h"
  53 #include "xmalloc.h"
  54 #include "packet.h"
  55 #include "buffer.h"
  56 #include "bufaux.h"
  57 #include "channels.h"
  58 #include "key.h"
  59 #include "authfd.h"
  60 #include "authfile.h"
  61 #include "pathnames.h"
  62 #include "dispatch.h"
  63 #include "clientloop.h"
  64 #include "log.h"
  65 #include "readconf.h"
  66 #include "sshconnect.h"
  67 #include "misc.h"
  68 #include "kex.h"
  69 #include "mac.h"
  70 #include "sshpty.h"
  71 #include "match.h"
  72 #include "msg.h"
  73 #include "monitor_fdpass.h"
  74 #include "uidswap.h"
  75
  76 #ifdef SMARTCARD
  77 #include "scard.h"
  78 #endif
  79
  80 extern char *__progname;
  81
  82 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
  83 int debug_flag = 0;
  84
  85 /* Flag indicating whether a tty should be allocated */
  86 int tty_flag = 0;
  87 int no_tty_flag = 0;
  88 int force_tty_flag = 0;
  89
  90 /* don't exec a shell */
  91 int no_shell_flag = 0;
  92
  93 /*
  94  * Flag indicating that nothing should be read from stdin.  This can be set
  95  * on the command line.
  96  */
  97 int stdin_null_flag = 0;
  98
  99 /*
 100  * Flag indicating that ssh should fork after authentication.  This is useful
 101  * so that the passphrase can be entered manually, and then ssh goes to the
 102  * background.
 103  */
 104 int fork_after_authentication_flag = 0;
 105
 106 /*
 107  * General data structure for command line options and options configurable
 108  * in configuration files.  See readconf.h.
 109  */
 110 Options options;
 111
 112 /* optional user configfile */
 113 char *config = NULL;
 114
 115 /*
 116  * Name of the host we are connecting to.  This is the name given on the
 117  * command line, or the HostName specified for the user-supplied name in a
 118  * configuration file.
 119  */
 120 char *host;
 121
 122 /* socket address the host resolves to */
 123 struct sockaddr_storage hostaddr;
 124
 125 /* Private host keys. */
 126 Sensitive sensitive_data;
 127
 128 /* Original real UID. */
 129 uid_t original_real_uid;
 130 uid_t original_effective_uid;
 131
 132 /* command to be executed */
 133 Buffer command;
 134
 135 /* Should we execute a command or invoke a subsystem? */
 136 int subsystem_flag = 0;
 137
 138 /* # of replies received for global requests */
 139 static int client_global_request_id = 0;
 140
 141 /* pid of proxycommand child process */
 142 pid_t proxy_command_pid = 0;
 143
 144 /* fd to control socket */
 145 int control_fd = -1;
 146
 147 /* Multiplexing control command */
 148 static u_int mux_command = SSHMUX_COMMAND_OPEN;
 149
 150 /* Only used in control client mode */
 151 volatile sig_atomic_t control_client_terminate = 0;
 152 u_int control_server_pid = 0;
 153
 154 /* Prints a help message to the user.  This function never returns. */
 155
 156 static void
 157 usage(void)
 158 {
 159         fprintf(stderr,
 160 "usage: ssh [-1246AaCfgkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 161 "           [-D port] [-e escape_char] [-F configfile] [-i identity_file]\n"
 162 "           [-L port:host:hostport] [-l login_name] [-m mac_spec] [-O ctl_cmd]\n"
 163 "           [-o option] [-p port] [-R port:host:hostport] [-S ctl_path]\n"
 164 "           [user@]hostname [command]\n"
 165         );
 166         exit(1);
 167 }
 168
 169 static int ssh_session(void);
 170 static int ssh_session2(void);
 171 static void load_public_identity_files(void);
 172 static void control_client(const char *path);
 173
 174 /*
 175  * Main program for the ssh client.
 176  */
 177 int
 178 main(int ac, char **av)
 179 {
 180         int i, opt, exit_status;
 181         u_short fwd_port, fwd_host_port;
 182         char sfwd_port[6], sfwd_host_port[6];
 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
 190         __progname = ssh_get_progname(av[0]);
 191         init_rng();
 192
 193         /*
 194          * Save the original real uid.  It will be needed later (uid-swapping
 195          * may clobber the real uid).
 196          */
 197         original_real_uid = getuid();
 198         original_effective_uid = geteuid();
 199
 200         /*
 201          * Use uid-swapping to give up root privileges for the duration of
 202          * option processing.  We will re-instantiate the rights when we are
 203          * ready to create the privileged port, and will permanently drop
 204          * them when the port has been created (actually, when the connection
 205          * has been made, as we may need to create the port several times).
 206          */
 207         PRIV_END;
 208
 209 #ifdef HAVE_SETRLIMIT
 210         /* If we are installed setuid root be careful to not drop core. */
 211         if (original_real_uid != original_effective_uid) {
 212                 struct rlimit rlim;
 213                 rlim.rlim_cur = rlim.rlim_max = 0;
 214                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 215                         fatal("setrlimit failed: %.100s", strerror(errno));
 216         }
 217 #endif
 218         /* Get user data. */
 219         pw = getpwuid(original_real_uid);
 220         if (!pw) {
 221                 logit("You don't exist, go away!");
 222                 exit(1);
 223         }
 224         /* Take a copy of the returned structure. */
 225         pw = pwcopy(pw);
 226
 227         /*
 228          * Set our umask to something reasonable, as some files are created
 229          * with the default umask.  This will make them world-readable but
 230          * writable only by the owner, which is ok for all files for which we
 231          * don't set the modes explicitly.
 232          */
 233         umask(022);
 234
 235         /* Initialize option structure to indicate that no values have been set. */
 236         initialize_options(&options);
 237
 238         /* Parse command-line arguments. */
 239         host = NULL;
 240
 241 again:
 242         while ((opt = getopt(ac, av,
 243             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:MNO:PR:S:TVXY")) != -1) {
 244                 switch (opt) {
 245                 case '1':
 246                         options.protocol = SSH_PROTO_1;
 247                         break;
 248                 case '2':
 249                         options.protocol = SSH_PROTO_2;
 250                         break;
 251                 case '4':
 252                         options.address_family = AF_INET;
 253                         break;
 254                 case '6':
 255                         options.address_family = AF_INET6;
 256                         break;
 257                 case 'n':
 258                         stdin_null_flag = 1;
 259                         break;
 260                 case 'f':
 261                         fork_after_authentication_flag = 1;
 262                         stdin_null_flag = 1;
 263                         break;
 264                 case 'x':
 265                         options.forward_x11 = 0;
 266                         break;
 267                 case 'X':
 268                         options.forward_x11 = 1;
 269                         break;
 270                 case 'Y':
 271                         options.forward_x11 = 1;
 272                         options.forward_x11_trusted = 1;
 273                         break;
 274                 case 'g':
 275                         options.gateway_ports = 1;
 276                         break;
 277                 case 'O':
 278                         if (strcmp(optarg, "check") == 0)
 279                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 280                         else if (strcmp(optarg, "exit") == 0)
 281                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 282                         else
 283                                 fatal("Invalid multiplex command.");
 284                         break;
 285                 case 'P':       /* deprecated */
 286                         options.use_privileged_port = 0;
 287                         break;
 288                 case 'a':
 289                         options.forward_agent = 0;
 290                         break;
 291                 case 'A':
 292                         options.forward_agent = 1;
 293                         break;
 294                 case 'k':
 295                         options.gss_deleg_creds = 0;
 296                         break;
 297                 case 'i':
 298                         if (stat(optarg, &st) < 0) {
 299                                 fprintf(stderr, "Warning: Identity file %s "
 300                                     "not accessible: %s.\n", optarg,
 301                                     strerror(errno));
 302                                 break;
 303                         }
 304                         if (options.num_identity_files >=
 305                             SSH_MAX_IDENTITY_FILES)
 306                                 fatal("Too many identity files specified "
 307                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 308                         options.identity_files[options.num_identity_files++] =
 309                             xstrdup(optarg);
 310                         break;
 311                 case 'I':
 312 #ifdef SMARTCARD
 313                         options.smartcard_device = xstrdup(optarg);
 314 #else
 315                         fprintf(stderr, "no support for smartcards.\n");
 316 #endif
 317                         break;
 318                 case 't':
 319                         if (tty_flag)
 320                                 force_tty_flag = 1;
 321                         tty_flag = 1;
 322                         break;
 323                 case 'v':
 324                         if (debug_flag == 0) {
 325                                 debug_flag = 1;
 326                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 327                         } else {
 328                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 329                                         options.log_level++;
 330                                 break;
 331                         }
 332                         /* FALLTHROUGH */
 333                 case 'V':
 334                         fprintf(stderr, "%s, %s\n",
 335                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 336                         if (opt == 'V')
 337                                 exit(0);
 338                         break;
 339                 case 'q':
 340                         options.log_level = SYSLOG_LEVEL_QUIET;
 341                         break;
 342                 case 'e':
 343                         if (optarg[0] == '^' && optarg[2] == 0 &&
 344                             (u_char) optarg[1] >= 64 &&
 345                             (u_char) optarg[1] < 128)
 346                                 options.escape_char = (u_char) optarg[1] & 31;
 347                         else if (strlen(optarg) == 1)
 348                                 options.escape_char = (u_char) optarg[0];
 349                         else if (strcmp(optarg, "none") == 0)
 350                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 351                         else {
 352                                 fprintf(stderr, "Bad escape character '%s'.\n",
 353                                     optarg);
 354                                 exit(1);
 355                         }
 356                         break;
 357                 case 'c':
 358                         if (ciphers_valid(optarg)) {
 359                                 /* SSH2 only */
 360                                 options.ciphers = xstrdup(optarg);
 361                                 options.cipher = SSH_CIPHER_INVALID;
 362                         } else {
 363                                 /* SSH1 only */
 364                                 options.cipher = cipher_number(optarg);
 365                                 if (options.cipher == -1) {
 366                                         fprintf(stderr,
 367                                             "Unknown cipher type '%s'\n",
 368                                             optarg);
 369                                         exit(1);
 370                                 }
 371                                 if (options.cipher == SSH_CIPHER_3DES)
 372                                         options.ciphers = "3des-cbc";
 373                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 374                                         options.ciphers = "blowfish-cbc";
 375                                 else
 376                                         options.ciphers = (char *)-1;
 377                         }
 378                         break;
 379                 case 'm':
 380                         if (mac_valid(optarg))
 381                                 options.macs = xstrdup(optarg);
 382                         else {
 383                                 fprintf(stderr, "Unknown mac type '%s'\n",
 384                                     optarg);
 385                                 exit(1);
 386                         }
 387                         break;
 388                 case 'M':
 389                         options.control_master =
 390                             (options.control_master >= 1) ? 2 : 1;
 391                         break;
 392                 case 'p':
 393                         options.port = a2port(optarg);
 394                         if (options.port == 0) {
 395                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 396                                 exit(1);
 397                         }
 398                         break;
 399                 case 'l':
 400                         options.user = optarg;
 401                         break;
 402
 403                 case 'L':
 404                 case 'R':
 405                         if (sscanf(optarg, "%5[0123456789]:%255[^:]:%5[0123456789]",
 406                             sfwd_port, buf, sfwd_host_port) != 3 &&
 407                             sscanf(optarg, "%5[0123456789]/%255[^/]/%5[0123456789]",
 408                             sfwd_port, buf, sfwd_host_port) != 3) {
 409                                 fprintf(stderr,
 410                                     "Bad forwarding specification '%s'\n",
 411                                     optarg);
 412                                 usage();
 413                                 /* NOTREACHED */
 414                         }
 415                         if ((fwd_port = a2port(sfwd_port)) == 0 ||
 416                             (fwd_host_port = a2port(sfwd_host_port)) == 0) {
 417                                 fprintf(stderr,
 418                                     "Bad forwarding port(s) '%s'\n", optarg);
 419                                 exit(1);
 420                         }
 421                         if (opt == 'L')
 422                                 add_local_forward(&options, fwd_port, buf,
 423                                     fwd_host_port);
 424                         else if (opt == 'R')
 425                                 add_remote_forward(&options, fwd_port, buf,
 426                                     fwd_host_port);
 427                         break;
 428
 429                 case 'D':
 430                         fwd_port = a2port(optarg);
 431                         if (fwd_port == 0) {
 432                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 433                                     optarg);
 434                                 exit(1);
 435                         }
 436                         add_local_forward(&options, fwd_port, "socks", 0);
 437                         break;
 438
 439                 case 'C':
 440                         options.compression = 1;
 441                         break;
 442                 case 'N':
 443                         no_shell_flag = 1;
 444                         no_tty_flag = 1;
 445                         break;
 446                 case 'T':
 447                         no_tty_flag = 1;
 448                         break;
 449                 case 'o':
 450                         dummy = 1;
 451                         line = xstrdup(optarg);
 452                         if (process_config_line(&options, host ? host : "",
 453                             line, "command-line", 0, &dummy) != 0)
 454                                 exit(1);
 455                         xfree(line);
 456                         break;
 457                 case 's':
 458                         subsystem_flag = 1;
 459                         break;
 460                 case 'S':
 461                         if (options.control_path != NULL)
 462                                 free(options.control_path);
 463                         options.control_path = xstrdup(optarg);
 464                         break;
 465                 case 'b':
 466                         options.bind_address = optarg;
 467                         break;
 468                 case 'F':
 469                         config = optarg;
 470                         break;
 471                 default:
 472                         usage();
 473                 }
 474         }
 475
 476         ac -= optind;
 477         av += optind;
 478
 479         if (ac > 0 && !host && **av != '-') {
 480                 if (strrchr(*av, '@')) {
 481                         p = xstrdup(*av);
 482                         cp = strrchr(p, '@');
 483                         if (cp == NULL || cp == p)
 484                                 usage();
 485                         options.user = p;
 486                         *cp = '\0';
 487                         host = ++cp;
 488                 } else
 489                         host = *av;
 490                 if (ac > 1) {
 491                         optind = optreset = 1;
 492                         goto again;
 493                 }
 494                 ac--, av++;
 495         }
 496
 497         /* Check that we got a host name. */
 498         if (!host)
 499                 usage();
 500
 501         SSLeay_add_all_algorithms();
 502         ERR_load_crypto_strings();
 503
 504         /* Initialize the command to execute on remote host. */
 505         buffer_init(&command);
 506
 507         /*
 508          * Save the command to execute on the remote host in a buffer. There
 509          * is no limit on the length of the command, except by the maximum
 510          * packet size.  Also sets the tty flag if there is no command.
 511          */
 512         if (!ac) {
 513                 /* No command specified - execute shell on a tty. */
 514                 tty_flag = 1;
 515                 if (subsystem_flag) {
 516                         fprintf(stderr,
 517                             "You must specify a subsystem to invoke.\n");
 518                         usage();
 519                 }
 520         } else {
 521                 /* A command has been specified.  Store it into the buffer. */
 522                 for (i = 0; i < ac; i++) {
 523                         if (i)
 524                                 buffer_append(&command, " ", 1);
 525                         buffer_append(&command, av[i], strlen(av[i]));
 526                 }
 527         }
 528
 529         /* Cannot fork to background if no command. */
 530         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 531                 fatal("Cannot fork into background without a command to execute.");
 532
 533         /* Allocate a tty by default if no command specified. */
 534         if (buffer_len(&command) == 0)
 535                 tty_flag = 1;
 536
 537         /* Force no tty */
 538         if (no_tty_flag)
 539                 tty_flag = 0;
 540         /* Do not allocate a tty if stdin is not a tty. */
 541         if (!isatty(fileno(stdin)) && !force_tty_flag) {
 542                 if (tty_flag)
 543                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 544                 tty_flag = 0;
 545         }
 546
 547         /*
 548          * Initialize "log" output.  Since we are the client all output
 549          * actually goes to stderr.
 550          */
 551         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 552             SYSLOG_FACILITY_USER, 1);
 553
 554         /*
 555          * Read per-user configuration file.  Ignore the system wide config
 556          * file if the user specifies a config file on the command line.
 557          */
 558         if (config != NULL) {
 559                 if (!read_config_file(config, host, &options, 0))
 560                         fatal("Can't open user config file %.100s: "
 561                             "%.100s", config, strerror(errno));
 562         } else  {
 563                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 564                     _PATH_SSH_USER_CONFFILE);
 565                 (void)read_config_file(buf, host, &options, 1);
 566
 567                 /* Read systemwide configuration file after use config. */
 568                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 569                     &options, 0);
 570         }
 571
 572         /* Fill configuration defaults. */
 573         fill_default_options(&options);
 574
 575         channel_set_af(options.address_family);
 576
 577         /* reinit */
 578         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 579
 580         seed_rng();
 581
 582         if (options.user == NULL)
 583                 options.user = xstrdup(pw->pw_name);
 584
 585         if (options.hostname != NULL)
 586                 host = options.hostname;
 587
 588         /* force lowercase for hostkey matching */
 589         if (options.host_key_alias != NULL) {
 590                 for (p = options.host_key_alias; *p; p++)
 591                         if (isupper(*p))
 592                                 *p = tolower(*p);
 593         }
 594
 595         if (options.proxy_command != NULL &&
 596             strcmp(options.proxy_command, "none") == 0)
 597                 options.proxy_command = NULL;
 598
 599         if (options.control_path != NULL) {
 600                 options.control_path = tilde_expand_filename(
 601                    options.control_path, original_real_uid);
 602         }
 603         if (options.control_path != NULL && options.control_master == 0)
 604                 control_client(options.control_path); /* This doesn't return */
 605
 606         /* Open a connection to the remote host. */
 607         if (ssh_connect(host, &hostaddr, options.port,
 608             options.address_family, options.connection_attempts,
 609 #ifdef HAVE_CYGWIN
 610             options.use_privileged_port,
 611 #else
 612             original_effective_uid == 0 && options.use_privileged_port,
 613 #endif
 614             options.proxy_command) != 0)
 615                 exit(1);
 616
 617         /*
 618          * If we successfully made the connection, load the host private key
 619          * in case we will need it later for combined rsa-rhosts
 620          * authentication. This must be done before releasing extra
 621          * privileges, because the file is only readable by root.
 622          * If we cannot access the private keys, load the public keys
 623          * instead and try to execute the ssh-keysign helper instead.
 624          */
 625         sensitive_data.nkeys = 0;
 626         sensitive_data.keys = NULL;
 627         sensitive_data.external_keysign = 0;
 628         if (options.rhosts_rsa_authentication ||
 629             options.hostbased_authentication) {
 630                 sensitive_data.nkeys = 3;
 631                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 632                     sizeof(Key));
 633
 634                 PRIV_START;
 635                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 636                     _PATH_HOST_KEY_FILE, "", NULL);
 637                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 638                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 639                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 640                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 641                 PRIV_END;
 642
 643                 if (options.hostbased_authentication == 1 &&
 644                     sensitive_data.keys[0] == NULL &&
 645                     sensitive_data.keys[1] == NULL &&
 646                     sensitive_data.keys[2] == NULL) {
 647                         sensitive_data.keys[1] = key_load_public(
 648                             _PATH_HOST_DSA_KEY_FILE, NULL);
 649                         sensitive_data.keys[2] = key_load_public(
 650                             _PATH_HOST_RSA_KEY_FILE, NULL);
 651                         sensitive_data.external_keysign = 1;
 652                 }
 653         }
 654         /*
 655          * Get rid of any extra privileges that we may have.  We will no
 656          * longer need them.  Also, extra privileges could make it very hard
 657          * to read identity files and other non-world-readable files from the
 658          * user's home directory if it happens to be on a NFS volume where
 659          * root is mapped to nobody.
 660          */
 661         if (original_effective_uid == 0) {
 662                 PRIV_START;
 663                 permanently_set_uid(pw);
 664         }
 665
 666         /*
 667          * Now that we are back to our own permissions, create ~/.ssh
 668          * directory if it doesn\'t already exist.
 669          */
 670         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 671         if (stat(buf, &st) < 0)
 672                 if (mkdir(buf, 0700) < 0)
 673                         error("Could not create directory '%.200s'.", buf);
 674
 675         /* load options.identity_files */
 676         load_public_identity_files();
 677
 678         /* Expand ~ in known host file names. */
 679         /* XXX mem-leaks: */
 680         options.system_hostfile =
 681             tilde_expand_filename(options.system_hostfile, original_real_uid);
 682         options.user_hostfile =
 683             tilde_expand_filename(options.user_hostfile, original_real_uid);
 684         options.system_hostfile2 =
 685             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 686         options.user_hostfile2 =
 687             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 688
 689         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 690
 691         /* Log into the remote system.  This never returns if the login fails. */
 692         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 693
 694         /* We no longer need the private host keys.  Clear them now. */
 695         if (sensitive_data.nkeys != 0) {
 696                 for (i = 0; i < sensitive_data.nkeys; i++) {
 697                         if (sensitive_data.keys[i] != NULL) {
 698                                 /* Destroys contents safely */
 699                                 debug3("clear hostkey %d", i);
 700                                 key_free(sensitive_data.keys[i]);
 701                                 sensitive_data.keys[i] = NULL;
 702                         }
 703                 }
 704                 xfree(sensitive_data.keys);
 705         }
 706         for (i = 0; i < options.num_identity_files; i++) {
 707                 if (options.identity_files[i]) {
 708                         xfree(options.identity_files[i]);
 709                         options.identity_files[i] = NULL;
 710                 }
 711                 if (options.identity_keys[i]) {
 712                         key_free(options.identity_keys[i]);
 713                         options.identity_keys[i] = NULL;
 714                 }
 715         }
 716
 717         exit_status = compat20 ? ssh_session2() : ssh_session();
 718         packet_close();
 719
 720         if (options.control_path != NULL && control_fd != -1)
 721                 unlink(options.control_path);
 722
 723         /*
 724          * Send SIGHUP to proxy command if used. We don't wait() in
 725          * case it hangs and instead rely on init to reap the child
 726          */
 727         if (proxy_command_pid > 1)
 728                 kill(proxy_command_pid, SIGHUP);
 729
 730         return exit_status;
 731 }
 732
 733 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
 734
 735 static void
 736 x11_get_proto(char **_proto, char **_data)
 737 {
 738         char cmd[1024];
 739         char line[512];
 740         char xdisplay[512];
 741         static char proto[512], data[512];
 742         FILE *f;
 743         int got_data = 0, generated = 0, do_unlink = 0, i;
 744         char *display, *xauthdir, *xauthfile;
 745         struct stat st;
 746
 747         xauthdir = xauthfile = NULL;
 748         *_proto = proto;
 749         *_data = data;
 750         proto[0] = data[0] = '\0';
 751
 752         if (!options.xauth_location ||
 753             (stat(options.xauth_location, &st) == -1)) {
 754                 debug("No xauth program.");
 755         } else {
 756                 if ((display = getenv("DISPLAY")) == NULL) {
 757                         debug("x11_get_proto: DISPLAY not set");
 758                         return;
 759                 }
 760                 /*
 761                  * Handle FamilyLocal case where $DISPLAY does
 762                  * not match an authorization entry.  For this we
 763                  * just try "xauth list unix:displaynum.screennum".
 764                  * XXX: "localhost" match to determine FamilyLocal
 765                  *      is not perfect.
 766                  */
 767                 if (strncmp(display, "localhost:", 10) == 0) {
 768                         snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
 769                             display + 10);
 770                         display = xdisplay;
 771                 }
 772                 if (options.forward_x11_trusted == 0) {
 773                         xauthdir = xmalloc(MAXPATHLEN);
 774                         xauthfile = xmalloc(MAXPATHLEN);
 775                         strlcpy(xauthdir, "/tmp/ssh-XXXXXXXXXX", MAXPATHLEN);
 776                         if (mkdtemp(xauthdir) != NULL) {
 777                                 do_unlink = 1;
 778                                 snprintf(xauthfile, MAXPATHLEN, "%s/xauthfile",
 779                                     xauthdir);
 780                                 snprintf(cmd, sizeof(cmd),
 781                                     "%s -f %s generate %s " SSH_X11_PROTO
 782                                     " untrusted timeout 1200 2>" _PATH_DEVNULL,
 783                                     options.xauth_location, xauthfile, display);
 784                                 debug2("x11_get_proto: %s", cmd);
 785                                 if (system(cmd) == 0)
 786                                         generated = 1;
 787                         }
 788                 }
 789                 snprintf(cmd, sizeof(cmd),
 790                     "%s %s%s list %s . 2>" _PATH_DEVNULL,
 791                     options.xauth_location,
 792                     generated ? "-f " : "" ,
 793                     generated ? xauthfile : "",
 794                     display);
 795                 debug2("x11_get_proto: %s", cmd);
 796                 f = popen(cmd, "r");
 797                 if (f && fgets(line, sizeof(line), f) &&
 798                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 799                         got_data = 1;
 800                 if (f)
 801                         pclose(f);
 802         }
 803
 804         if (do_unlink) {
 805                 unlink(xauthfile);
 806                 rmdir(xauthdir);
 807         }
 808         if (xauthdir)
 809                 xfree(xauthdir);
 810         if (xauthfile)
 811                 xfree(xauthfile);
 812
 813         /*
 814          * If we didn't get authentication data, just make up some
 815          * data.  The forwarding code will check the validity of the
 816          * response anyway, and substitute this data.  The X11
 817          * server, however, will ignore this fake data and use
 818          * whatever authentication mechanisms it was using otherwise
 819          * for the local connection.
 820          */
 821         if (!got_data) {
 822                 u_int32_t rnd = 0;
 823
 824                 logit("Warning: No xauth data; "
 825                     "using fake authentication data for X11 forwarding.");
 826                 strlcpy(proto, SSH_X11_PROTO, sizeof proto);
 827                 for (i = 0; i < 16; i++) {
 828                         if (i % 4 == 0)
 829                                 rnd = arc4random();
 830                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
 831                             rnd & 0xff);
 832                         rnd >>= 8;
 833                 }
 834         }
 835 }
 836
 837 static void
 838 ssh_init_forwarding(void)
 839 {
 840         int success = 0;
 841         int i;
 842
 843         /* Initiate local TCP/IP port forwardings. */
 844         for (i = 0; i < options.num_local_forwards; i++) {
 845                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
 846                     options.local_forwards[i].port,
 847                     options.local_forwards[i].host,
 848                     options.local_forwards[i].host_port);
 849                 success += channel_setup_local_fwd_listener(
 850                     options.local_forwards[i].port,
 851                     options.local_forwards[i].host,
 852                     options.local_forwards[i].host_port,
 853                     options.gateway_ports);
 854         }
 855         if (i > 0 && success == 0)
 856                 error("Could not request local forwarding.");
 857
 858         /* Initiate remote TCP/IP port forwardings. */
 859         for (i = 0; i < options.num_remote_forwards; i++) {
 860                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
 861                     options.remote_forwards[i].port,
 862                     options.remote_forwards[i].host,
 863                     options.remote_forwards[i].host_port);
 864                 channel_request_remote_forwarding(
 865                     options.remote_forwards[i].port,
 866                     options.remote_forwards[i].host,
 867                     options.remote_forwards[i].host_port);
 868         }
 869 }
 870
 871 static void
 872 check_agent_present(void)
 873 {
 874         if (options.forward_agent) {
 875                 /* Clear agent forwarding if we don\'t have an agent. */
 876                 if (!ssh_agent_present())
 877                         options.forward_agent = 0;
 878         }
 879 }
 880
 881 static int
 882 ssh_session(void)
 883 {
 884         int type;
 885         int interactive = 0;
 886         int have_tty = 0;
 887         struct winsize ws;
 888         char *cp;
 889
 890         /* Enable compression if requested. */
 891         if (options.compression) {
 892                 debug("Requesting compression at level %d.", options.compression_level);
 893
 894                 if (options.compression_level < 1 || options.compression_level > 9)
 895                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 896
 897                 /* Send the request. */
 898                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 899                 packet_put_int(options.compression_level);
 900                 packet_send();
 901                 packet_write_wait();
 902                 type = packet_read();
 903                 if (type == SSH_SMSG_SUCCESS)
 904                         packet_start_compression(options.compression_level);
 905                 else if (type == SSH_SMSG_FAILURE)
 906                         logit("Warning: Remote host refused compression.");
 907                 else
 908                         packet_disconnect("Protocol error waiting for compression response.");
 909         }
 910         /* Allocate a pseudo tty if appropriate. */
 911         if (tty_flag) {
 912                 debug("Requesting pty.");
 913
 914                 /* Start the packet. */
 915                 packet_start(SSH_CMSG_REQUEST_PTY);
 916
 917                 /* Store TERM in the packet.  There is no limit on the
 918                    length of the string. */
 919                 cp = getenv("TERM");
 920                 if (!cp)
 921                         cp = "";
 922                 packet_put_cstring(cp);
 923
 924                 /* Store window size in the packet. */
 925                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 926                         memset(&ws, 0, sizeof(ws));
 927                 packet_put_int(ws.ws_row);
 928                 packet_put_int(ws.ws_col);
 929                 packet_put_int(ws.ws_xpixel);
 930                 packet_put_int(ws.ws_ypixel);
 931
 932                 /* Store tty modes in the packet. */
 933                 tty_make_modes(fileno(stdin), NULL);
 934
 935                 /* Send the packet, and wait for it to leave. */
 936                 packet_send();
 937                 packet_write_wait();
 938
 939                 /* Read response from the server. */
 940                 type = packet_read();
 941                 if (type == SSH_SMSG_SUCCESS) {
 942                         interactive = 1;
 943                         have_tty = 1;
 944                 } else if (type == SSH_SMSG_FAILURE)
 945                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 946                 else
 947                         packet_disconnect("Protocol error waiting for pty request response.");
 948         }
 949         /* Request X11 forwarding if enabled and DISPLAY is set. */
 950         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 951                 char *proto, *data;
 952                 /* Get reasonable local authentication information. */
 953                 x11_get_proto(&proto, &data);
 954                 /* Request forwarding with authentication spoofing. */
 955                 debug("Requesting X11 forwarding with authentication spoofing.");
 956                 x11_request_forwarding_with_spoofing(0, proto, data);
 957
 958                 /* Read response from the server. */
 959                 type = packet_read();
 960                 if (type == SSH_SMSG_SUCCESS) {
 961                         interactive = 1;
 962                 } else if (type == SSH_SMSG_FAILURE) {
 963                         logit("Warning: Remote host denied X11 forwarding.");
 964                 } else {
 965                         packet_disconnect("Protocol error waiting for X11 forwarding");
 966                 }
 967         }
 968         /* Tell the packet module whether this is an interactive session. */
 969         packet_set_interactive(interactive);
 970
 971         /* Request authentication agent forwarding if appropriate. */
 972         check_agent_present();
 973
 974         if (options.forward_agent) {
 975                 debug("Requesting authentication agent forwarding.");
 976                 auth_request_forwarding();
 977
 978                 /* Read response from the server. */
 979                 type = packet_read();
 980                 packet_check_eom();
 981                 if (type != SSH_SMSG_SUCCESS)
 982                         logit("Warning: Remote host denied authentication agent forwarding.");
 983         }
 984
 985         /* Initiate port forwardings. */
 986         ssh_init_forwarding();
 987
 988         /* If requested, let ssh continue in the background. */
 989         if (fork_after_authentication_flag)
 990                 if (daemon(1, 1) < 0)
 991                         fatal("daemon() failed: %.200s", strerror(errno));
 992
 993         /*
 994          * If a command was specified on the command line, execute the
 995          * command now. Otherwise request the server to start a shell.
 996          */
 997         if (buffer_len(&command) > 0) {
 998                 int len = buffer_len(&command);
 999                 if (len > 900)
1000                         len = 900;
1001                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1002                 packet_start(SSH_CMSG_EXEC_CMD);
1003                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1004                 packet_send();
1005                 packet_write_wait();
1006         } else {
1007                 debug("Requesting shell.");
1008                 packet_start(SSH_CMSG_EXEC_SHELL);
1009                 packet_send();
1010                 packet_write_wait();
1011         }
1012
1013         /* Enter the interactive session. */
1014         return client_loop(have_tty, tty_flag ?
1015             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1016 }
1017
1018 static void
1019 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1020 {
1021         int id, len;
1022
1023         id = packet_get_int();
1024         len = buffer_len(&command);
1025         if (len > 900)
1026                 len = 900;
1027         packet_check_eom();
1028         if (type == SSH2_MSG_CHANNEL_FAILURE)
1029                 fatal("Request for subsystem '%.*s' failed on channel %d",
1030                     len, (u_char *)buffer_ptr(&command), id);
1031 }
1032
1033 void
1034 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1035 {
1036         int i;
1037
1038         i = client_global_request_id++;
1039         if (i >= options.num_remote_forwards)
1040                 return;
1041         debug("remote forward %s for: listen %d, connect %s:%d",
1042             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1043             options.remote_forwards[i].port,
1044             options.remote_forwards[i].host,
1045             options.remote_forwards[i].host_port);
1046         if (type == SSH2_MSG_REQUEST_FAILURE)
1047                 logit("Warning: remote port forwarding failed for listen port %d",
1048                     options.remote_forwards[i].port);
1049 }
1050
1051 static void
1052 ssh_control_listener(void)
1053 {
1054         struct sockaddr_un addr;
1055         mode_t old_umask;
1056         int addr_len;
1057
1058         if (options.control_path == NULL || options.control_master <= 0)
1059                 return;
1060
1061         memset(&addr, '\0', sizeof(addr));
1062         addr.sun_family = AF_UNIX;
1063         addr_len = offsetof(struct sockaddr_un, sun_path) +
1064             strlen(options.control_path) + 1;
1065
1066         if (strlcpy(addr.sun_path, options.control_path,
1067             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1068                 fatal("ControlPath too long");
1069
1070         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1071                 fatal("%s socket(): %s\n", __func__, strerror(errno));
1072
1073         old_umask = umask(0177);
1074         if (bind(control_fd, (struct sockaddr*)&addr, addr_len) == -1) {
1075                 control_fd = -1;
1076                 if (errno == EINVAL)
1077                         fatal("ControlSocket %s already exists",
1078                             options.control_path);
1079                 else
1080                         fatal("%s bind(): %s\n", __func__, strerror(errno));
1081         }
1082         umask(old_umask);
1083
1084         if (listen(control_fd, 64) == -1)
1085                 fatal("%s listen(): %s\n", __func__, strerror(errno));
1086
1087         set_nonblock(control_fd);
1088 }
1089
1090 /* request pty/x11/agent/tcpfwd/shell for channel */
1091 static void
1092 ssh_session2_setup(int id, void *arg)
1093 {
1094         extern char **environ;
1095
1096         int interactive = tty_flag;
1097         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
1098                 char *proto, *data;
1099                 /* Get reasonable local authentication information. */
1100                 x11_get_proto(&proto, &data);
1101                 /* Request forwarding with authentication spoofing. */
1102                 debug("Requesting X11 forwarding with authentication spoofing.");
1103                 x11_request_forwarding_with_spoofing(id, proto, data);
1104                 interactive = 1;
1105                 /* XXX wait for reply */
1106         }
1107
1108         check_agent_present();
1109         if (options.forward_agent) {
1110                 debug("Requesting authentication agent forwarding.");
1111                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1112                 packet_send();
1113         }
1114
1115         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1116             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1117
1118         packet_set_interactive(interactive);
1119 }
1120
1121 /* open new channel for a session */
1122 static int
1123 ssh_session2_open(void)
1124 {
1125         Channel *c;
1126         int window, packetmax, in, out, err;
1127
1128         if (stdin_null_flag) {
1129                 in = open(_PATH_DEVNULL, O_RDONLY);
1130         } else {
1131                 in = dup(STDIN_FILENO);
1132         }
1133         out = dup(STDOUT_FILENO);
1134         err = dup(STDERR_FILENO);
1135
1136         if (in < 0 || out < 0 || err < 0)
1137                 fatal("dup() in/out/err failed");
1138
1139         /* enable nonblocking unless tty */
1140         if (!isatty(in))
1141                 set_nonblock(in);
1142         if (!isatty(out))
1143                 set_nonblock(out);
1144         if (!isatty(err))
1145                 set_nonblock(err);
1146
1147         window = CHAN_SES_WINDOW_DEFAULT;
1148         packetmax = CHAN_SES_PACKET_DEFAULT;
1149         if (tty_flag) {
1150                 window >>= 1;
1151                 packetmax >>= 1;
1152         }
1153         c = channel_new(
1154             "session", SSH_CHANNEL_OPENING, in, out, err,
1155             window, packetmax, CHAN_EXTENDED_WRITE,
1156             "client-session", /*nonblock*/0);
1157
1158         debug3("ssh_session2_open: channel_new: %d", c->self);
1159
1160         channel_send_open(c->self);
1161         if (!no_shell_flag)
1162                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1163
1164         return c->self;
1165 }
1166
1167 static int
1168 ssh_session2(void)
1169 {
1170         int id = -1;
1171
1172         /* XXX should be pre-session */
1173         ssh_init_forwarding();
1174         ssh_control_listener();
1175
1176         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1177                 id = ssh_session2_open();
1178
1179         /* If requested, let ssh continue in the background. */
1180         if (fork_after_authentication_flag)
1181                 if (daemon(1, 1) < 0)
1182                         fatal("daemon() failed: %.200s", strerror(errno));
1183
1184         return client_loop(tty_flag, tty_flag ?
1185             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1186 }
1187
1188 static void
1189 load_public_identity_files(void)
1190 {
1191         char *filename;
1192         int i = 0;
1193         Key *public;
1194 #ifdef SMARTCARD
1195         Key **keys;
1196
1197         if (options.smartcard_device != NULL &&
1198             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1199             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1200                 int count = 0;
1201                 for (i = 0; keys[i] != NULL; i++) {
1202                         count++;
1203                         memmove(&options.identity_files[1], &options.identity_files[0],
1204                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1205                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1206                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1207                         options.num_identity_files++;
1208                         options.identity_keys[0] = keys[i];
1209                         options.identity_files[0] = sc_get_key_label(keys[i]);
1210                 }
1211                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1212                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1213                 i = count;
1214                 xfree(keys);
1215         }
1216 #endif /* SMARTCARD */
1217         for (; i < options.num_identity_files; i++) {
1218                 filename = tilde_expand_filename(options.identity_files[i],
1219                     original_real_uid);
1220                 public = key_load_public(filename, NULL);
1221                 debug("identity file %s type %d", filename,
1222                     public ? public->type : -1);
1223                 xfree(options.identity_files[i]);
1224                 options.identity_files[i] = filename;
1225                 options.identity_keys[i] = public;
1226         }
1227 }
1228
1229 static void
1230 control_client_sighandler(int signo)
1231 {
1232         control_client_terminate = signo;
1233 }
1234
1235 static void
1236 control_client_sigrelay(int signo)
1237 {
1238         if (control_server_pid > 1)
1239                 kill(control_server_pid, signo);
1240 }
1241
1242 static int
1243 env_permitted(char *env)
1244 {
1245         int i;
1246         char name[1024], *cp;
1247
1248         strlcpy(name, env, sizeof(name));
1249         if ((cp = strchr(name, '=')) == NULL)
1250                 return (0);
1251
1252         *cp = '\0';
1253
1254         for (i = 0; i < options.num_send_env; i++)
1255                 if (match_pattern(name, options.send_env[i]))
1256                         return (1);
1257
1258         return (0);
1259 }
1260
1261 static void
1262 control_client(const char *path)
1263 {
1264         struct sockaddr_un addr;
1265         int i, r, fd, sock, exitval, num_env, addr_len;
1266         Buffer m;
1267         char *term;
1268         extern char **environ;
1269         u_int  flags;
1270
1271         if (stdin_null_flag) {
1272                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1273                         fatal("open(/dev/null): %s", strerror(errno));
1274                 if (dup2(fd, STDIN_FILENO) == -1)
1275                         fatal("dup2: %s", strerror(errno));
1276                 if (fd > STDERR_FILENO)
1277                         close(fd);
1278         }
1279
1280         memset(&addr, '\0', sizeof(addr));
1281         addr.sun_family = AF_UNIX;
1282         addr_len = offsetof(struct sockaddr_un, sun_path) +
1283             strlen(path) + 1;
1284
1285         if (strlcpy(addr.sun_path, path,
1286             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1287                 fatal("ControlPath too long");
1288
1289         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1290                 fatal("%s socket(): %s", __func__, strerror(errno));
1291
1292         if (connect(sock, (struct sockaddr*)&addr, addr_len) == -1)
1293                 fatal("Couldn't connect to %s: %s", path, strerror(errno));
1294
1295         if ((term = getenv("TERM")) == NULL)
1296                 term = "";
1297
1298         flags = 0;
1299         if (tty_flag)
1300                 flags |= SSHMUX_FLAG_TTY;
1301         if (subsystem_flag)
1302                 flags |= SSHMUX_FLAG_SUBSYS;
1303
1304         buffer_init(&m);
1305
1306         /* Send our command to server */
1307         buffer_put_int(&m, mux_command);
1308         buffer_put_int(&m, flags);
1309         if (ssh_msg_send(sock, /* version */1, &m) == -1)
1310                 fatal("%s: msg_send", __func__);
1311         buffer_clear(&m);
1312
1313         /* Get authorisation status and PID of controlee */
1314         if (ssh_msg_recv(sock, &m) == -1)
1315                 fatal("%s: msg_recv", __func__);
1316         if (buffer_get_char(&m) != 1)
1317                 fatal("%s: wrong version", __func__);
1318         if (buffer_get_int(&m) != 1)
1319                 fatal("Connection to master denied");
1320         control_server_pid = buffer_get_int(&m);
1321
1322         buffer_clear(&m);
1323
1324         switch (mux_command) {
1325         case SSHMUX_COMMAND_ALIVE_CHECK:
1326                 fprintf(stderr, "Master running (pid=%d)\r\n",
1327                     control_server_pid);
1328                 exit(0);
1329         case SSHMUX_COMMAND_TERMINATE:
1330                 fprintf(stderr, "Exit request sent.\r\n");
1331                 exit(0);
1332         case SSHMUX_COMMAND_OPEN:
1333                 /* continue below */
1334                 break;
1335         default:
1336                 fatal("silly mux_command %d", mux_command);
1337         }
1338
1339         /* SSHMUX_COMMAND_OPEN */
1340         buffer_put_cstring(&m, term);
1341         buffer_append(&command, "\0", 1);
1342         buffer_put_cstring(&m, buffer_ptr(&command));
1343
1344         if (options.num_send_env == 0 || environ == NULL) {
1345                 buffer_put_int(&m, 0);
1346         } else {
1347                 /* Pass environment */
1348                 num_env = 0;
1349                 for (i = 0; environ[i] != NULL; i++)
1350                         if (env_permitted(environ[i]))
1351                                 num_env++; /* Count */
1352
1353                 buffer_put_int(&m, num_env);
1354
1355                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1356                         if (env_permitted(environ[i])) {
1357                                 num_env--;
1358                                 buffer_put_cstring(&m, environ[i]);
1359                         }
1360         }
1361
1362         if (ssh_msg_send(sock, /* version */1, &m) == -1)
1363                 fatal("%s: msg_send", __func__);
1364
1365         mm_send_fd(sock, STDIN_FILENO);
1366         mm_send_fd(sock, STDOUT_FILENO);
1367         mm_send_fd(sock, STDERR_FILENO);
1368
1369         /* Wait for reply, so master has a chance to gather ttymodes */
1370         buffer_clear(&m);
1371         if (ssh_msg_recv(sock, &m) == -1)
1372                 fatal("%s: msg_recv", __func__);
1373         if (buffer_get_char(&m) != 1)
1374                 fatal("%s: wrong version", __func__);
1375         buffer_free(&m);
1376
1377         signal(SIGHUP, control_client_sighandler);
1378         signal(SIGINT, control_client_sighandler);
1379         signal(SIGTERM, control_client_sighandler);
1380         signal(SIGWINCH, control_client_sigrelay);
1381
1382         if (tty_flag)
1383                 enter_raw_mode();
1384
1385         /* Stick around until the controlee closes the client_fd */
1386         exitval = 0;
1387         for (;!control_client_terminate;) {
1388                 r = read(sock, &exitval, sizeof(exitval));
1389                 if (r == 0) {
1390                         debug2("Received EOF from master");
1391                         break;
1392                 }
1393                 if (r > 0)
1394                         debug2("Received exit status from master %d", exitval);
1395                 if (r == -1 && errno != EINTR)
1396                         fatal("%s: read %s", __func__, strerror(errno));
1397         }
1398
1399         if (control_client_terminate)
1400                 debug2("Exiting on signal %d", control_client_terminate);
1401
1402         close(sock);
1403
1404         leave_raw_mode();
1405
1406         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1407                 fprintf(stderr, "Connection to master closed.\r\n");
1408
1409         exit(exitval);
1410 }