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 1.224 2004/07/28 09:40:29 markus 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 /* Only used in control client mode */
 148 volatile sig_atomic_t control_client_terminate = 0;
 149 u_int control_server_pid = 0;
 150
 151 /* Prints a help message to the user.  This function never returns. */
 152
 153 static void
 154 usage(void)
 155 {
 156         fprintf(stderr,
 157 "usage: ssh [-1246AaCfghkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 158 "           [-D port] [-e escape_char] [-F configfile] [-i identity_file]\n"
 159 "           [-L port:host:hostport] [-l login_name] [-m mac_spec] [-o option]\n"
 160 "           [-p port] [-R port:host:hostport] [-S ctl] [user@]hostname [command]\n"
 161         );
 162         exit(1);
 163 }
 164
 165 static int ssh_session(void);
 166 static int ssh_session2(void);
 167 static void load_public_identity_files(void);
 168 static void control_client(const char *path);
 169
 170 /*
 171  * Main program for the ssh client.
 172  */
 173 int
 174 main(int ac, char **av)
 175 {
 176         int i, opt, exit_status;
 177         u_short fwd_port, fwd_host_port;
 178         char sfwd_port[6], sfwd_host_port[6];
 179         char *p, *cp, *line, buf[256];
 180         struct stat st;
 181         struct passwd *pw;
 182         int dummy;
 183         extern int optind, optreset;
 184         extern char *optarg;
 185
 186         __progname = ssh_get_progname(av[0]);
 187         init_pathnames();
 188         init_rng();
 189
 190         /*
 191          * Save the original real uid.  It will be needed later (uid-swapping
 192          * may clobber the real uid).
 193          */
 194         original_real_uid = getuid();
 195         original_effective_uid = geteuid();
 196
 197         /*
 198          * Use uid-swapping to give up root privileges for the duration of
 199          * option processing.  We will re-instantiate the rights when we are
 200          * ready to create the privileged port, and will permanently drop
 201          * them when the port has been created (actually, when the connection
 202          * has been made, as we may need to create the port several times).
 203          */
 204         PRIV_END;
 205
 206 #ifdef HAVE_SETRLIMIT
 207         /* If we are installed setuid root be careful to not drop core. */
 208         if (original_real_uid != original_effective_uid) {
 209                 struct rlimit rlim;
 210                 rlim.rlim_cur = rlim.rlim_max = 0;
 211                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 212                         fatal("setrlimit failed: %.100s", strerror(errno));
 213         }
 214 #endif
 215         /* Get user data. */
 216         pw = getpwuid(original_real_uid);
 217         if (!pw) {
 218                 logit("You don't exist, go away!");
 219                 exit(1);
 220         }
 221         /* Take a copy of the returned structure. */
 222         pw = pwcopy(pw);
 223
 224         /*
 225          * Set our umask to something reasonable, as some files are created
 226          * with the default umask.  This will make them world-readable but
 227          * writable only by the owner, which is ok for all files for which we
 228          * don't set the modes explicitly.
 229          */
 230         umask(022);
 231
 232         /* Initialize option structure to indicate that no values have been set. */
 233         initialize_options(&options);
 234
 235         /* Parse command-line arguments. */
 236         host = NULL;
 237
 238 again:
 239         while ((opt = getopt(ac, av,
 240             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:MNPR:S:TVXY")) != -1) {
 241                 switch (opt) {
 242                 case '1':
 243                         options.protocol = SSH_PROTO_1;
 244                         break;
 245                 case '2':
 246                         options.protocol = SSH_PROTO_2;
 247                         break;
 248                 case '4':
 249                         options.address_family = AF_INET;
 250                         break;
 251                 case '6':
 252                         options.address_family = AF_INET6;
 253                         break;
 254                 case 'n':
 255                         stdin_null_flag = 1;
 256                         break;
 257                 case 'f':
 258                         fork_after_authentication_flag = 1;
 259                         stdin_null_flag = 1;
 260                         break;
 261                 case 'x':
 262                         options.forward_x11 = 0;
 263                         break;
 264                 case 'X':
 265                         options.forward_x11 = 1;
 266                         break;
 267                 case 'Y':
 268                         options.forward_x11 = 1;
 269                         options.forward_x11_trusted = 1;
 270                         break;
 271                 case 'g':
 272                         options.gateway_ports = 1;
 273                         break;
 274                 case 'P':       /* deprecated */
 275                         options.use_privileged_port = 0;
 276                         break;
 277                 case 'a':
 278                         options.forward_agent = 0;
 279                         break;
 280                 case 'A':
 281                         options.forward_agent = 1;
 282                         break;
 283                 case 'k':
 284                         options.gss_deleg_creds = 0;
 285                         break;
 286                 case 'i':
 287                         if (stat(optarg, &st) < 0) {
 288                                 fprintf(stderr, "Warning: Identity file %s "
 289                                     "does not exist.\n", optarg);
 290                                 break;
 291                         }
 292                         if (options.num_identity_files >=
 293                             SSH_MAX_IDENTITY_FILES)
 294                                 fatal("Too many identity files specified "
 295                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 296                         options.identity_files[options.num_identity_files++] =
 297                             xstrdup(optarg);
 298                         break;
 299                 case 'I':
 300 #ifdef SMARTCARD
 301                         options.smartcard_device = xstrdup(optarg);
 302 #else
 303                         fprintf(stderr, "no support for smartcards.\n");
 304 #endif
 305                         break;
 306                 case 't':
 307                         if (tty_flag)
 308                                 force_tty_flag = 1;
 309                         tty_flag = 1;
 310                         break;
 311                 case 'v':
 312                         if (debug_flag == 0) {
 313                                 debug_flag = 1;
 314                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 315                         } else {
 316                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 317                                         options.log_level++;
 318                                 break;
 319                         }
 320                         /* fallthrough */
 321                 case 'V':
 322                         fprintf(stderr, "%s, %s\n",
 323                             SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
 324                         if (opt == 'V')
 325                                 exit(0);
 326                         break;
 327                 case 'q':
 328                         options.log_level = SYSLOG_LEVEL_QUIET;
 329                         break;
 330                 case 'e':
 331                         if (optarg[0] == '^' && optarg[2] == 0 &&
 332                             (u_char) optarg[1] >= 64 &&
 333                             (u_char) optarg[1] < 128)
 334                                 options.escape_char = (u_char) optarg[1] & 31;
 335                         else if (strlen(optarg) == 1)
 336                                 options.escape_char = (u_char) optarg[0];
 337                         else if (strcmp(optarg, "none") == 0)
 338                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 339                         else {
 340                                 fprintf(stderr, "Bad escape character '%s'.\n",
 341                                     optarg);
 342                                 exit(1);
 343                         }
 344                         break;
 345                 case 'c':
 346                         if (ciphers_valid(optarg)) {
 347                                 /* SSH2 only */
 348                                 options.ciphers = xstrdup(optarg);
 349                                 options.cipher = SSH_CIPHER_INVALID;
 350                         } else {
 351                                 /* SSH1 only */
 352                                 options.cipher = cipher_number(optarg);
 353                                 if (options.cipher == -1) {
 354                                         fprintf(stderr,
 355                                             "Unknown cipher type '%s'\n",
 356                                             optarg);
 357                                         exit(1);
 358                                 }
 359                                 if (options.cipher == SSH_CIPHER_3DES)
 360                                         options.ciphers = "3des-cbc";
 361                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 362                                         options.ciphers = "blowfish-cbc";
 363                                 else
 364                                         options.ciphers = (char *)-1;
 365                         }
 366                         break;
 367                 case 'm':
 368                         if (mac_valid(optarg))
 369                                 options.macs = xstrdup(optarg);
 370                         else {
 371                                 fprintf(stderr, "Unknown mac type '%s'\n",
 372                                     optarg);
 373                                 exit(1);
 374                         }
 375                         break;
 376                 case 'M':
 377                         options.control_master =
 378                             (options.control_master >= 1) ? 2 : 1;
 379                         break;
 380                 case 'p':
 381                         options.port = a2port(optarg);
 382                         if (options.port == 0) {
 383                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 384                                 exit(1);
 385                         }
 386                         break;
 387                 case 'l':
 388                         options.user = optarg;
 389                         break;
 390
 391                 case 'L':
 392                 case 'R':
 393                         if (sscanf(optarg, "%5[0123456789]:%255[^:]:%5[0123456789]",
 394                             sfwd_port, buf, sfwd_host_port) != 3 &&
 395                             sscanf(optarg, "%5[0123456789]/%255[^/]/%5[0123456789]",
 396                             sfwd_port, buf, sfwd_host_port) != 3) {
 397                                 fprintf(stderr,
 398                                     "Bad forwarding specification '%s'\n",
 399                                     optarg);
 400                                 usage();
 401                                 /* NOTREACHED */
 402                         }
 403                         if ((fwd_port = a2port(sfwd_port)) == 0 ||
 404                             (fwd_host_port = a2port(sfwd_host_port)) == 0) {
 405                                 fprintf(stderr,
 406                                     "Bad forwarding port(s) '%s'\n", optarg);
 407                                 exit(1);
 408                         }
 409                         if (opt == 'L')
 410                                 add_local_forward(&options, fwd_port, buf,
 411                                     fwd_host_port);
 412                         else if (opt == 'R')
 413                                 add_remote_forward(&options, fwd_port, buf,
 414                                     fwd_host_port);
 415                         break;
 416
 417                 case 'D':
 418                         fwd_port = a2port(optarg);
 419                         if (fwd_port == 0) {
 420                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 421                                     optarg);
 422                                 exit(1);
 423                         }
 424                         add_local_forward(&options, fwd_port, "socks", 0);
 425                         break;
 426
 427                 case 'C':
 428                         options.compression = 1;
 429                         break;
 430                 case 'N':
 431                         no_shell_flag = 1;
 432                         no_tty_flag = 1;
 433                         break;
 434                 case 'T':
 435                         no_tty_flag = 1;
 436                         break;
 437                 case 'o':
 438                         dummy = 1;
 439                         line = xstrdup(optarg);
 440                         if (process_config_line(&options, host ? host : "",
 441                             line, "command-line", 0, &dummy) != 0)
 442                                 exit(1);
 443                         xfree(line);
 444                         break;
 445                 case 's':
 446                         subsystem_flag = 1;
 447                         break;
 448                 case 'S':
 449                         if (options.control_path != NULL)
 450                                 free(options.control_path);
 451                         options.control_path = xstrdup(optarg);
 452                         break;
 453                 case 'b':
 454                         options.bind_address = optarg;
 455                         break;
 456                 case 'F':
 457                         config = optarg;
 458                         break;
 459                 default:
 460                         usage();
 461                 }
 462         }
 463
 464         ac -= optind;
 465         av += optind;
 466
 467         if (ac > 0 && !host && **av != '-') {
 468                 if (strrchr(*av, '@')) {
 469                         p = xstrdup(*av);
 470                         cp = strrchr(p, '@');
 471                         if (cp == NULL || cp == p)
 472                                 usage();
 473                         options.user = p;
 474                         *cp = '\0';
 475                         host = ++cp;
 476                 } else
 477                         host = *av;
 478                 if (ac > 1) {
 479                         optind = optreset = 1;
 480                         goto again;
 481                 }
 482                 ac--, av++;
 483         }
 484
 485         /* Check that we got a host name. */
 486         if (!host)
 487                 usage();
 488
 489         SSLeay_add_all_algorithms();
 490         ERR_load_crypto_strings();
 491
 492         /* Initialize the command to execute on remote host. */
 493         buffer_init(&command);
 494
 495         /*
 496          * Save the command to execute on the remote host in a buffer. There
 497          * is no limit on the length of the command, except by the maximum
 498          * packet size.  Also sets the tty flag if there is no command.
 499          */
 500         if (!ac) {
 501                 /* No command specified - execute shell on a tty. */
 502                 tty_flag = 1;
 503                 if (subsystem_flag) {
 504                         fprintf(stderr,
 505                             "You must specify a subsystem to invoke.\n");
 506                         usage();
 507                 }
 508         } else {
 509                 /* A command has been specified.  Store it into the buffer. */
 510                 for (i = 0; i < ac; i++) {
 511                         if (i)
 512                                 buffer_append(&command, " ", 1);
 513                         buffer_append(&command, av[i], strlen(av[i]));
 514                 }
 515         }
 516
 517         /* Cannot fork to background if no command. */
 518         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 519                 fatal("Cannot fork into background without a command to execute.");
 520
 521         /* Allocate a tty by default if no command specified. */
 522         if (buffer_len(&command) == 0)
 523                 tty_flag = 1;
 524
 525         /* Force no tty */
 526         if (no_tty_flag)
 527                 tty_flag = 0;
 528         /* Do not allocate a tty if stdin is not a tty. */
 529         if (!isatty(fileno(stdin)) && !force_tty_flag) {
 530                 if (tty_flag)
 531                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 532                 tty_flag = 0;
 533         }
 534
 535         /*
 536          * Initialize "log" output.  Since we are the client all output
 537          * actually goes to stderr.
 538          */
 539         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 540             SYSLOG_FACILITY_USER, 1);
 541
 542         /*
 543          * Read per-user configuration file.  Ignore the system wide config
 544          * file if the user specifies a config file on the command line.
 545          */
 546         if (config != NULL) {
 547                 if (!read_config_file(config, host, &options, 0))
 548                         fatal("Can't open user config file %.100s: "
 549                             "%.100s", config, strerror(errno));
 550         } else  {
 551             /*
 552              * Since the config file parsing code aborts if it sees
 553              * options it doesn't recognize, allow users to put
 554              * options specific to compile-time add-ons in alternate
 555              * config files so their primary config file will
 556              * interoperate SSH versions that don't support those
 557              * options.
 558              */
 559 #ifdef GSSAPI
 560                 snprintf(buf, sizeof buf, "%.100s/%.100s.gssapi", pw->pw_dir,
 561                     _PATH_SSH_USER_CONFFILE);
 562                 (void)read_config_file(buf, host, &options, 1);
 563 #ifdef GSI
 564                 snprintf(buf, sizeof buf, "%.100s/%.100s.gsi", pw->pw_dir,
 565                     _PATH_SSH_USER_CONFFILE);
 566                 (void)read_config_file(buf, host, &options, 1);
 567 #endif
 568 #if defined(KRB5)
 569                 snprintf(buf, sizeof buf, "%.100s/%.100s.krb", pw->pw_dir,
 570                     _PATH_SSH_USER_CONFFILE);
 571                 (void)read_config_file(buf, host, &options, 1);
 572 #endif
 573 #endif
 574                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 575                     _PATH_SSH_USER_CONFFILE);
 576                 (void)read_config_file(buf, host, &options, 1);
 577
 578                 /* Read systemwide configuration file after use config. */
 579                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 580                     &options, 0);
 581         }
 582
 583         /* Fill configuration defaults. */
 584         fill_default_options(&options);
 585
 586         channel_set_af(options.address_family);
 587
 588         /* reinit */
 589         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 590
 591         seed_rng();
 592
 593         if (options.user == NULL) {
 594                 options.user = xstrdup(pw->pw_name);
 595                 options.implicit = 1;
 596         }
 597         else options.implicit = 0;
 598
 599         if (options.hostname != NULL)
 600                 host = options.hostname;
 601
 602         /* force lowercase for hostkey matching */
 603         if (options.host_key_alias != NULL) {
 604                 for (p = options.host_key_alias; *p; p++)
 605                         if (isupper(*p))
 606                                 *p = tolower(*p);
 607         }
 608
 609         if (options.proxy_command != NULL &&
 610             strcmp(options.proxy_command, "none") == 0)
 611                 options.proxy_command = NULL;
 612
 613         if (options.control_path != NULL) {
 614                 options.control_path = tilde_expand_filename(
 615                    options.control_path, original_real_uid);
 616         }
 617         if (options.control_path != NULL && options.control_master == 0)
 618                 control_client(options.control_path); /* This doesn't return */
 619
 620         /* Open a connection to the remote host. */
 621         if (ssh_connect(host, &hostaddr, options.port,
 622             options.address_family, options.connection_attempts,
 623 #ifdef HAVE_CYGWIN
 624             options.use_privileged_port,
 625 #else
 626             original_effective_uid == 0 && options.use_privileged_port,
 627 #endif
 628             options.proxy_command) != 0)
 629                 exit(1);
 630
 631         /*
 632          * If we successfully made the connection, load the host private key
 633          * in case we will need it later for combined rsa-rhosts
 634          * authentication. This must be done before releasing extra
 635          * privileges, because the file is only readable by root.
 636          * If we cannot access the private keys, load the public keys
 637          * instead and try to execute the ssh-keysign helper instead.
 638          */
 639         sensitive_data.nkeys = 0;
 640         sensitive_data.keys = NULL;
 641         sensitive_data.external_keysign = 0;
 642         if (options.rhosts_rsa_authentication ||
 643             options.hostbased_authentication) {
 644                 sensitive_data.nkeys = 3;
 645                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 646                     sizeof(Key));
 647
 648                 PRIV_START;
 649                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 650                     _PATH_HOST_KEY_FILE, "", NULL);
 651                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 652                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 653                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 654                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 655                 PRIV_END;
 656
 657                 if (options.hostbased_authentication == 1 &&
 658                     sensitive_data.keys[0] == NULL &&
 659                     sensitive_data.keys[1] == NULL &&
 660                     sensitive_data.keys[2] == NULL) {
 661                         sensitive_data.keys[1] = key_load_public(
 662                             _PATH_HOST_DSA_KEY_FILE, NULL);
 663                         sensitive_data.keys[2] = key_load_public(
 664                             _PATH_HOST_RSA_KEY_FILE, NULL);
 665                         sensitive_data.external_keysign = 1;
 666                 }
 667         }
 668         /*
 669          * Get rid of any extra privileges that we may have.  We will no
 670          * longer need them.  Also, extra privileges could make it very hard
 671          * to read identity files and other non-world-readable files from the
 672          * user's home directory if it happens to be on a NFS volume where
 673          * root is mapped to nobody.
 674          */
 675         if (original_effective_uid == 0) {
 676                 PRIV_START;
 677                 permanently_set_uid(pw);
 678         }
 679
 680         /*
 681          * Now that we are back to our own permissions, create ~/.ssh
 682          * directory if it doesn\'t already exist.
 683          */
 684         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 685         if (stat(buf, &st) < 0)
 686                 if (mkdir(buf, 0700) < 0)
 687                         error("Could not create directory '%.200s'.", buf);
 688
 689         /* load options.identity_files */
 690         load_public_identity_files();
 691
 692         /* Expand ~ in known host file names. */
 693         /* XXX mem-leaks: */
 694         options.system_hostfile =
 695             tilde_expand_filename(options.system_hostfile, original_real_uid);
 696         options.user_hostfile =
 697             tilde_expand_filename(options.user_hostfile, original_real_uid);
 698         options.system_hostfile2 =
 699             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 700         options.user_hostfile2 =
 701             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 702
 703         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 704
 705         /* Log into the remote system.  This never returns if the login fails. */
 706         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 707
 708         /* We no longer need the private host keys.  Clear them now. */
 709         if (sensitive_data.nkeys != 0) {
 710                 for (i = 0; i < sensitive_data.nkeys; i++) {
 711                         if (sensitive_data.keys[i] != NULL) {
 712                                 /* Destroys contents safely */
 713                                 debug3("clear hostkey %d", i);
 714                                 key_free(sensitive_data.keys[i]);
 715                                 sensitive_data.keys[i] = NULL;
 716                         }
 717                 }
 718                 xfree(sensitive_data.keys);
 719         }
 720         for (i = 0; i < options.num_identity_files; i++) {
 721                 if (options.identity_files[i]) {
 722                         xfree(options.identity_files[i]);
 723                         options.identity_files[i] = NULL;
 724                 }
 725                 if (options.identity_keys[i]) {
 726                         key_free(options.identity_keys[i]);
 727                         options.identity_keys[i] = NULL;
 728                 }
 729         }
 730
 731         exit_status = compat20 ? ssh_session2() : ssh_session();
 732         packet_close();
 733
 734         if (options.control_path != NULL && control_fd != -1)
 735                 unlink(options.control_path);
 736
 737         /*
 738          * Send SIGHUP to proxy command if used. We don't wait() in
 739          * case it hangs and instead rely on init to reap the child
 740          */
 741         if (proxy_command_pid > 1)
 742                 kill(proxy_command_pid, SIGHUP);
 743
 744         return exit_status;
 745 }
 746
 747 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
 748
 749 static void
 750 x11_get_proto(char **_proto, char **_data)
 751 {
 752         char cmd[1024];
 753         char line[512];
 754         char xdisplay[512];
 755         static char proto[512], data[512];
 756         FILE *f;
 757         int got_data = 0, generated = 0, do_unlink = 0, i;
 758         char *display, *xauthdir, *xauthfile;
 759         struct stat st;
 760
 761         xauthdir = xauthfile = NULL;
 762         *_proto = proto;
 763         *_data = data;
 764         proto[0] = data[0] = '\0';
 765
 766         if (!options.xauth_location ||
 767             (stat(options.xauth_location, &st) == -1)) {
 768                 debug("No xauth program.");
 769         } else {
 770                 if ((display = getenv("DISPLAY")) == NULL) {
 771                         debug("x11_get_proto: DISPLAY not set");
 772                         return;
 773                 }
 774                 /*
 775                  * Handle FamilyLocal case where $DISPLAY does
 776                  * not match an authorization entry.  For this we
 777                  * just try "xauth list unix:displaynum.screennum".
 778                  * XXX: "localhost" match to determine FamilyLocal
 779                  *      is not perfect.
 780                  */
 781                 if (strncmp(display, "localhost:", 10) == 0) {
 782                         snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
 783                             display + 10);
 784                         display = xdisplay;
 785                 }
 786                 if (options.forward_x11_trusted == 0) {
 787                         xauthdir = xmalloc(MAXPATHLEN);
 788                         xauthfile = xmalloc(MAXPATHLEN);
 789                         strlcpy(xauthdir, "/tmp/ssh-XXXXXXXXXX", MAXPATHLEN);
 790                         if (mkdtemp(xauthdir) != NULL) {
 791                                 do_unlink = 1;
 792                                 snprintf(xauthfile, MAXPATHLEN, "%s/xauthfile",
 793                                     xauthdir);
 794                                 snprintf(cmd, sizeof(cmd),
 795                                     "%s -f %s generate %s " SSH_X11_PROTO
 796                                     " untrusted timeout 1200 2>" _PATH_DEVNULL,
 797                                     options.xauth_location, xauthfile, display);
 798                                 debug2("x11_get_proto: %s", cmd);
 799                                 if (system(cmd) == 0)
 800                                         generated = 1;
 801                         }
 802                 }
 803                 snprintf(cmd, sizeof(cmd),
 804                     "%s %s%s list %s . 2>" _PATH_DEVNULL,
 805                     options.xauth_location,
 806                     generated ? "-f " : "" ,
 807                     generated ? xauthfile : "",
 808                     display);
 809                 debug2("x11_get_proto: %s", cmd);
 810                 f = popen(cmd, "r");
 811                 if (f && fgets(line, sizeof(line), f) &&
 812                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 813                         got_data = 1;
 814                 if (f)
 815                         pclose(f);
 816         }
 817
 818         if (do_unlink) {
 819                 unlink(xauthfile);
 820                 rmdir(xauthdir);
 821         }
 822         if (xauthdir)
 823                 xfree(xauthdir);
 824         if (xauthfile)
 825                 xfree(xauthfile);
 826
 827         /*
 828          * If we didn't get authentication data, just make up some
 829          * data.  The forwarding code will check the validity of the
 830          * response anyway, and substitute this data.  The X11
 831          * server, however, will ignore this fake data and use
 832          * whatever authentication mechanisms it was using otherwise
 833          * for the local connection.
 834          */
 835         if (!got_data) {
 836                 u_int32_t rnd = 0;
 837
 838                 logit("Warning: No xauth data; "
 839                     "using fake authentication data for X11 forwarding.");
 840                 strlcpy(proto, SSH_X11_PROTO, sizeof proto);
 841                 for (i = 0; i < 16; i++) {
 842                         if (i % 4 == 0)
 843                                 rnd = arc4random();
 844                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
 845                             rnd & 0xff);
 846                         rnd >>= 8;
 847                 }
 848         }
 849 }
 850
 851 static void
 852 ssh_init_forwarding(void)
 853 {
 854         int success = 0;
 855         int i;
 856
 857         /* Initiate local TCP/IP port forwardings. */
 858         for (i = 0; i < options.num_local_forwards; i++) {
 859                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
 860                     options.local_forwards[i].port,
 861                     options.local_forwards[i].host,
 862                     options.local_forwards[i].host_port);
 863                 success += channel_setup_local_fwd_listener(
 864                     options.local_forwards[i].port,
 865                     options.local_forwards[i].host,
 866                     options.local_forwards[i].host_port,
 867                     options.gateway_ports);
 868         }
 869         if (i > 0 && success == 0)
 870                 error("Could not request local forwarding.");
 871
 872         /* Initiate remote TCP/IP port forwardings. */
 873         for (i = 0; i < options.num_remote_forwards; i++) {
 874                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
 875                     options.remote_forwards[i].port,
 876                     options.remote_forwards[i].host,
 877                     options.remote_forwards[i].host_port);
 878                 channel_request_remote_forwarding(
 879                     options.remote_forwards[i].port,
 880                     options.remote_forwards[i].host,
 881                     options.remote_forwards[i].host_port);
 882         }
 883 }
 884
 885 static void
 886 check_agent_present(void)
 887 {
 888         if (options.forward_agent) {
 889                 /* Clear agent forwarding if we don\'t have an agent. */
 890                 if (!ssh_agent_present())
 891                         options.forward_agent = 0;
 892         }
 893 }
 894
 895 static int
 896 ssh_session(void)
 897 {
 898         int type;
 899         int interactive = 0;
 900         int have_tty = 0;
 901         struct winsize ws;
 902         char *cp;
 903
 904         /* Enable compression if requested. */
 905         if (options.compression) {
 906                 debug("Requesting compression at level %d.", options.compression_level);
 907
 908                 if (options.compression_level < 1 || options.compression_level > 9)
 909                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 910
 911                 /* Send the request. */
 912                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 913                 packet_put_int(options.compression_level);
 914                 packet_send();
 915                 packet_write_wait();
 916                 type = packet_read();
 917                 if (type == SSH_SMSG_SUCCESS)
 918                         packet_start_compression(options.compression_level);
 919                 else if (type == SSH_SMSG_FAILURE)
 920                         logit("Warning: Remote host refused compression.");
 921                 else
 922                         packet_disconnect("Protocol error waiting for compression response.");
 923         }
 924         /* Allocate a pseudo tty if appropriate. */
 925         if (tty_flag) {
 926                 debug("Requesting pty.");
 927
 928                 /* Start the packet. */
 929                 packet_start(SSH_CMSG_REQUEST_PTY);
 930
 931                 /* Store TERM in the packet.  There is no limit on the
 932                    length of the string. */
 933                 cp = getenv("TERM");
 934                 if (!cp)
 935                         cp = "";
 936                 packet_put_cstring(cp);
 937
 938                 /* Store window size in the packet. */
 939                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 940                         memset(&ws, 0, sizeof(ws));
 941                 packet_put_int(ws.ws_row);
 942                 packet_put_int(ws.ws_col);
 943                 packet_put_int(ws.ws_xpixel);
 944                 packet_put_int(ws.ws_ypixel);
 945
 946                 /* Store tty modes in the packet. */
 947                 tty_make_modes(fileno(stdin), NULL);
 948
 949                 /* Send the packet, and wait for it to leave. */
 950                 packet_send();
 951                 packet_write_wait();
 952
 953                 /* Read response from the server. */
 954                 type = packet_read();
 955                 if (type == SSH_SMSG_SUCCESS) {
 956                         interactive = 1;
 957                         have_tty = 1;
 958                 } else if (type == SSH_SMSG_FAILURE)
 959                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 960                 else
 961                         packet_disconnect("Protocol error waiting for pty request response.");
 962         }
 963         /* Request X11 forwarding if enabled and DISPLAY is set. */
 964         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 965                 char *proto, *data;
 966                 /* Get reasonable local authentication information. */
 967                 x11_get_proto(&proto, &data);
 968                 /* Request forwarding with authentication spoofing. */
 969                 debug("Requesting X11 forwarding with authentication spoofing.");
 970                 x11_request_forwarding_with_spoofing(0, proto, data);
 971
 972                 /* Read response from the server. */
 973                 type = packet_read();
 974                 if (type == SSH_SMSG_SUCCESS) {
 975                         interactive = 1;
 976                 } else if (type == SSH_SMSG_FAILURE) {
 977                         logit("Warning: Remote host denied X11 forwarding.");
 978                 } else {
 979                         packet_disconnect("Protocol error waiting for X11 forwarding");
 980                 }
 981         }
 982         /* Tell the packet module whether this is an interactive session. */
 983         packet_set_interactive(interactive);
 984
 985         /* Request authentication agent forwarding if appropriate. */
 986         check_agent_present();
 987
 988         if (options.forward_agent) {
 989                 debug("Requesting authentication agent forwarding.");
 990                 auth_request_forwarding();
 991
 992                 /* Read response from the server. */
 993                 type = packet_read();
 994                 packet_check_eom();
 995                 if (type != SSH_SMSG_SUCCESS)
 996                         logit("Warning: Remote host denied authentication agent forwarding.");
 997         }
 998
 999         /* Initiate port forwardings. */
1000         ssh_init_forwarding();
1001
1002         /* If requested, let ssh continue in the background. */
1003         if (fork_after_authentication_flag)
1004                 if (daemon(1, 1) < 0)
1005                         fatal("daemon() failed: %.200s", strerror(errno));
1006
1007         /*
1008          * If a command was specified on the command line, execute the
1009          * command now. Otherwise request the server to start a shell.
1010          */
1011         if (buffer_len(&command) > 0) {
1012                 int len = buffer_len(&command);
1013                 if (len > 900)
1014                         len = 900;
1015                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1016                 packet_start(SSH_CMSG_EXEC_CMD);
1017                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1018                 packet_send();
1019                 packet_write_wait();
1020         } else {
1021                 debug("Requesting shell.");
1022                 packet_start(SSH_CMSG_EXEC_SHELL);
1023                 packet_send();
1024                 packet_write_wait();
1025         }
1026
1027         /* Enter the interactive session. */
1028         return client_loop(have_tty, tty_flag ?
1029             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1030 }
1031
1032 static void
1033 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1034 {
1035         int id, len;
1036
1037         id = packet_get_int();
1038         len = buffer_len(&command);
1039         if (len > 900)
1040                 len = 900;
1041         packet_check_eom();
1042         if (type == SSH2_MSG_CHANNEL_FAILURE)
1043                 fatal("Request for subsystem '%.*s' failed on channel %d",
1044                     len, (u_char *)buffer_ptr(&command), id);
1045 }
1046
1047 void
1048 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1049 {
1050         int i;
1051
1052         i = client_global_request_id++;
1053         if (i >= options.num_remote_forwards)
1054                 return;
1055         debug("remote forward %s for: listen %d, connect %s:%d",
1056             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1057             options.remote_forwards[i].port,
1058             options.remote_forwards[i].host,
1059             options.remote_forwards[i].host_port);
1060         if (type == SSH2_MSG_REQUEST_FAILURE)
1061                 logit("Warning: remote port forwarding failed for listen port %d",
1062                     options.remote_forwards[i].port);
1063 }
1064
1065 static void
1066 ssh_control_listener(void)
1067 {
1068         struct sockaddr_un addr;
1069         mode_t old_umask;
1070         int addr_len;
1071
1072         if (options.control_path == NULL || options.control_master <= 0)
1073                 return;
1074
1075         memset(&addr, '\0', sizeof(addr));
1076         addr.sun_family = AF_UNIX;
1077         addr_len = offsetof(struct sockaddr_un, sun_path) +
1078             strlen(options.control_path) + 1;
1079
1080         if (strlcpy(addr.sun_path, options.control_path,
1081             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1082                 fatal("ControlPath too long");
1083
1084         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1085                 fatal("%s socket(): %s\n", __func__, strerror(errno));
1086
1087         old_umask = umask(0177);
1088         if (bind(control_fd, (struct sockaddr*)&addr, addr_len) == -1) {
1089                 control_fd = -1;
1090                 if (errno == EINVAL)
1091                         fatal("ControlSocket %s already exists",
1092                             options.control_path);
1093                 else
1094                         fatal("%s bind(): %s\n", __func__, strerror(errno));
1095         }
1096         umask(old_umask);
1097
1098         if (listen(control_fd, 64) == -1)
1099                 fatal("%s listen(): %s\n", __func__, strerror(errno));
1100
1101         set_nonblock(control_fd);
1102 }
1103
1104 /* request pty/x11/agent/tcpfwd/shell for channel */
1105 static void
1106 ssh_session2_setup(int id, void *arg)
1107 {
1108         extern char **environ;
1109
1110         int interactive = tty_flag;
1111         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
1112                 char *proto, *data;
1113                 /* Get reasonable local authentication information. */
1114                 x11_get_proto(&proto, &data);
1115                 /* Request forwarding with authentication spoofing. */
1116                 debug("Requesting X11 forwarding with authentication spoofing.");
1117                 x11_request_forwarding_with_spoofing(id, proto, data);
1118                 interactive = 1;
1119                 /* XXX wait for reply */
1120         }
1121
1122         check_agent_present();
1123         if (options.forward_agent) {
1124                 debug("Requesting authentication agent forwarding.");
1125                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1126                 packet_send();
1127         }
1128
1129         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1130             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1131
1132         packet_set_interactive(interactive);
1133 }
1134
1135 /* open new channel for a session */
1136 static int
1137 ssh_session2_open(void)
1138 {
1139         Channel *c;
1140         int window, packetmax, in, out, err;
1141
1142         if (stdin_null_flag) {
1143                 in = open(_PATH_DEVNULL, O_RDONLY);
1144         } else {
1145                 in = dup(STDIN_FILENO);
1146         }
1147         out = dup(STDOUT_FILENO);
1148         err = dup(STDERR_FILENO);
1149
1150         if (in < 0 || out < 0 || err < 0)
1151                 fatal("dup() in/out/err failed");
1152
1153         /* enable nonblocking unless tty */
1154         if (!isatty(in))
1155                 set_nonblock(in);
1156         if (!isatty(out))
1157                 set_nonblock(out);
1158         if (!isatty(err))
1159                 set_nonblock(err);
1160
1161         window = CHAN_SES_WINDOW_DEFAULT;
1162         packetmax = CHAN_SES_PACKET_DEFAULT;
1163         if (tty_flag) {
1164                 window >>= 1;
1165                 packetmax >>= 1;
1166         }
1167         c = channel_new(
1168             "session", SSH_CHANNEL_OPENING, in, out, err,
1169             window, packetmax, CHAN_EXTENDED_WRITE,
1170             "client-session", /*nonblock*/0);
1171
1172         debug3("ssh_session2_open: channel_new: %d", c->self);
1173
1174         channel_send_open(c->self);
1175         if (!no_shell_flag)
1176                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1177
1178         return c->self;
1179 }
1180
1181 static int
1182 ssh_session2(void)
1183 {
1184         int id = -1;
1185
1186         /* XXX should be pre-session */
1187         ssh_init_forwarding();
1188         ssh_control_listener();
1189
1190         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1191                 id = ssh_session2_open();
1192
1193         /* If requested, let ssh continue in the background. */
1194         if (fork_after_authentication_flag)
1195                 if (daemon(1, 1) < 0)
1196                         fatal("daemon() failed: %.200s", strerror(errno));
1197
1198         return client_loop(tty_flag, tty_flag ?
1199             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1200 }
1201
1202 static void
1203 load_public_identity_files(void)
1204 {
1205         char *filename;
1206         int i = 0;
1207         Key *public;
1208 #ifdef SMARTCARD
1209         Key **keys;
1210
1211         if (options.smartcard_device != NULL &&
1212             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1213             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1214                 int count = 0;
1215                 for (i = 0; keys[i] != NULL; i++) {
1216                         count++;
1217                         memmove(&options.identity_files[1], &options.identity_files[0],
1218                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1219                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1220                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1221                         options.num_identity_files++;
1222                         options.identity_keys[0] = keys[i];
1223                         options.identity_files[0] = sc_get_key_label(keys[i]);
1224                 }
1225                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1226                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1227                 i = count;
1228                 xfree(keys);
1229         }
1230 #endif /* SMARTCARD */
1231         for (; i < options.num_identity_files; i++) {
1232                 filename = tilde_expand_filename(options.identity_files[i],
1233                     original_real_uid);
1234                 public = key_load_public(filename, NULL);
1235                 debug("identity file %s type %d", filename,
1236                     public ? public->type : -1);
1237                 xfree(options.identity_files[i]);
1238                 options.identity_files[i] = filename;
1239                 options.identity_keys[i] = public;
1240         }
1241 }
1242
1243 static void
1244 control_client_sighandler(int signo)
1245 {
1246         control_client_terminate = signo;
1247 }
1248
1249 static void
1250 control_client_sigrelay(int signo)
1251 {
1252         if (control_server_pid > 1)
1253                 kill(control_server_pid, signo);
1254 }
1255
1256 static int
1257 env_permitted(char *env)
1258 {
1259         int i;
1260         char name[1024], *cp;
1261
1262         strlcpy(name, env, sizeof(name));
1263         if ((cp = strchr(name, '=')) == NULL)
1264                 return (0);
1265
1266         *cp = '\0';
1267
1268         for (i = 0; i < options.num_send_env; i++)
1269                 if (match_pattern(name, options.send_env[i]))
1270                         return (1);
1271
1272         return (0);
1273 }
1274
1275 static void
1276 control_client(const char *path)
1277 {
1278         struct sockaddr_un addr;
1279         int i, r, sock, exitval, num_env, addr_len;
1280         Buffer m;
1281         char *cp;
1282         extern char **environ;
1283
1284         memset(&addr, '\0', sizeof(addr));
1285         addr.sun_family = AF_UNIX;
1286         addr_len = offsetof(struct sockaddr_un, sun_path) +
1287             strlen(path) + 1;
1288
1289         if (strlcpy(addr.sun_path, path,
1290             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1291                 fatal("ControlPath too long");
1292
1293         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1294                 fatal("%s socket(): %s", __func__, strerror(errno));
1295
1296         if (connect(sock, (struct sockaddr*)&addr, addr_len) == -1)
1297                 fatal("Couldn't connect to %s: %s", path, strerror(errno));
1298
1299         if ((cp = getenv("TERM")) == NULL)
1300                 cp = "";
1301
1302         buffer_init(&m);
1303
1304         /* Get PID of controlee */
1305         if (ssh_msg_recv(sock, &m) == -1)
1306                 fatal("%s: msg_recv", __func__);
1307         if (buffer_get_char(&m) != 0)
1308                 fatal("%s: wrong version", __func__);
1309         /* Connection allowed? */
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         buffer_put_int(&m, tty_flag);
1316         buffer_put_int(&m, subsystem_flag);
1317         buffer_put_cstring(&m, cp);
1318
1319         buffer_append(&command, "\0", 1);
1320         buffer_put_cstring(&m, buffer_ptr(&command));
1321
1322         if (options.num_send_env == 0 || environ == NULL) {
1323                 buffer_put_int(&m, 0);
1324         } else {
1325                 /* Pass environment */
1326                 num_env = 0;
1327                 for (i = 0; environ[i] != NULL; i++)
1328                         if (env_permitted(environ[i]))
1329                                 num_env++; /* Count */
1330
1331                 buffer_put_int(&m, num_env);
1332
1333                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1334                         if (env_permitted(environ[i])) {
1335                                 num_env--;
1336                                 buffer_put_cstring(&m, environ[i]);
1337                         }
1338         }
1339
1340         if (ssh_msg_send(sock, /* version */0, &m) == -1)
1341                 fatal("%s: msg_send", __func__);
1342
1343         mm_send_fd(sock, STDIN_FILENO);
1344         mm_send_fd(sock, STDOUT_FILENO);
1345         mm_send_fd(sock, STDERR_FILENO);
1346
1347         /* Wait for reply, so master has a chance to gather ttymodes */
1348         buffer_clear(&m);
1349         if (ssh_msg_recv(sock, &m) == -1)
1350                 fatal("%s: msg_recv", __func__);
1351         if (buffer_get_char(&m) != 0)
1352                 fatal("%s: master returned error", __func__);
1353         buffer_free(&m);
1354
1355         signal(SIGINT, control_client_sighandler);
1356         signal(SIGTERM, control_client_sighandler);
1357         signal(SIGWINCH, control_client_sigrelay);
1358
1359         if (tty_flag)
1360                 enter_raw_mode();
1361
1362         /* Stick around until the controlee closes the client_fd */
1363         exitval = 0;
1364         for (;!control_client_terminate;) {
1365                 r = read(sock, &exitval, sizeof(exitval));
1366                 if (r == 0) {
1367                         debug2("Received EOF from master");
1368                         break;
1369                 }
1370                 if (r > 0)
1371                         debug2("Received exit status from master %d", exitval);
1372                 if (r == -1 && errno != EINTR)
1373                         fatal("%s: read %s", __func__, strerror(errno));
1374         }
1375
1376         if (control_client_terminate)
1377                 debug2("Exiting on signal %d", control_client_terminate);
1378
1379         close(sock);
1380
1381         leave_raw_mode();
1382
1383         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1384                 fprintf(stderr, "Connection to master closed.\r\n");
1385
1386         exit(exitval);
1387 }