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 1.242 2005/06/08 11:25:09 djm Exp $");
  44
  45 #include <openssl/evp.h>
  46 #include <openssl/err.h>
  47
  48 #include "ssh.h"
  49 #include "ssh1.h"
  50 #include "ssh2.h"
  51 #include "compat.h"
  52 #include "cipher.h"
  53 #include "xmalloc.h"
  54 #include "packet.h"
  55 #include "buffer.h"
  56 #include "bufaux.h"
  57 #include "channels.h"
  58 #include "key.h"
  59 #include "authfd.h"
  60 #include "authfile.h"
  61 #include "pathnames.h"
  62 #include "dispatch.h"
  63 #include "clientloop.h"
  64 #include "log.h"
  65 #include "readconf.h"
  66 #include "sshconnect.h"
  67 #include "misc.h"
  68 #include "kex.h"
  69 #include "mac.h"
  70 #include "sshpty.h"
  71 #include "match.h"
  72 #include "msg.h"
  73 #include "monitor_fdpass.h"
  74 #include "uidswap.h"
  75
  76 #ifdef SMARTCARD
  77 #include "scard.h"
  78 #endif
  79
  80 extern char *__progname;
  81
  82 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
  83 int debug_flag = 0;
  84
  85 /* Flag indicating whether a tty should be allocated */
  86 int tty_flag = 0;
  87 int no_tty_flag = 0;
  88 int force_tty_flag = 0;
  89
  90 /* don't exec a shell */
  91 int no_shell_flag = 0;
  92
  93 /*
  94  * Flag indicating that nothing should be read from stdin.  This can be set
  95  * on the command line.
  96  */
  97 int stdin_null_flag = 0;
  98
  99 /*
 100  * Flag indicating that ssh should fork after authentication.  This is useful
 101  * so that the passphrase can be entered manually, and then ssh goes to the
 102  * background.
 103  */
 104 int fork_after_authentication_flag = 0;
 105
 106 /*
 107  * General data structure for command line options and options configurable
 108  * in configuration files.  See readconf.h.
 109  */
 110 Options options;
 111
 112 /* optional user configfile */
 113 char *config = NULL;
 114
 115 /*
 116  * Name of the host we are connecting to.  This is the name given on the
 117  * command line, or the HostName specified for the user-supplied name in a
 118  * configuration file.
 119  */
 120 char *host;
 121
 122 /* socket address the host resolves to */
 123 struct sockaddr_storage hostaddr;
 124
 125 /* Private host keys. */
 126 Sensitive sensitive_data;
 127
 128 /* Original real UID. */
 129 uid_t original_real_uid;
 130 uid_t original_effective_uid;
 131
 132 /* command to be executed */
 133 Buffer command;
 134
 135 /* Should we execute a command or invoke a subsystem? */
 136 int subsystem_flag = 0;
 137
 138 /* # of replies received for global requests */
 139 static int client_global_request_id = 0;
 140
 141 /* pid of proxycommand child process */
 142 pid_t proxy_command_pid = 0;
 143
 144 /* fd to control socket */
 145 int control_fd = -1;
 146
 147 /* Multiplexing control command */
 148 static u_int mux_command = 0;
 149
 150 /* Only used in control client mode */
 151 volatile sig_atomic_t control_client_terminate = 0;
 152 u_int control_server_pid = 0;
 153
 154 /* Prints a help message to the user.  This function never returns. */
 155
 156 static void
 157 usage(void)
 158 {
 159         fprintf(stderr,
 160 "usage: ssh [-1246AaCfgkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 161 "           [-D port] [-e escape_char] [-F configfile]\n"
 162 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 163 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 164 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 165 "           [user@]hostname [command]\n"
 166         );
 167         exit(1);
 168 }
 169
 170 static int ssh_session(void);
 171 static int ssh_session2(void);
 172 static void load_public_identity_files(void);
 173 static void control_client(const char *path);
 174
 175 /*
 176  * Main program for the ssh client.
 177  */
 178 int
 179 main(int ac, char **av)
 180 {
 181         int i, opt, exit_status;
 182         char *p, *cp, *line, buf[256];
 183         struct stat st;
 184         struct passwd *pw;
 185         int dummy;
 186         extern int optind, optreset;
 187         extern char *optarg;
 188         Forward fwd;
 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                         if (options.control_master == SSHCTL_MASTER_YES)
 390                                 options.control_master = SSHCTL_MASTER_ASK;
 391                         else
 392                                 options.control_master = SSHCTL_MASTER_YES;
 393                         break;
 394                 case 'p':
 395                         options.port = a2port(optarg);
 396                         if (options.port == 0) {
 397                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 398                                 exit(1);
 399                         }
 400                         break;
 401                 case 'l':
 402                         options.user = optarg;
 403                         break;
 404
 405                 case 'L':
 406                         if (parse_forward(&fwd, optarg))
 407                                 add_local_forward(&options, &fwd);
 408                         else {
 409                                 fprintf(stderr,
 410                                     "Bad local forwarding specification '%s'\n",
 411                                     optarg);
 412                                 exit(1);
 413                         }
 414                         break;
 415
 416                 case 'R':
 417                         if (parse_forward(&fwd, optarg)) {
 418                                 add_remote_forward(&options, &fwd);
 419                         } else {
 420                                 fprintf(stderr,
 421                                     "Bad remote forwarding specification "
 422                                     "'%s'\n", optarg);
 423                                 exit(1);
 424                         }
 425                         break;
 426
 427                 case 'D':
 428                         cp = p = xstrdup(optarg);
 429                         memset(&fwd, '\0', sizeof(fwd));
 430                         fwd.connect_host = "socks";
 431                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 432                                 fprintf(stderr, "Bad dynamic forwarding "
 433                                     "specification '%.100s'\n", optarg);
 434                                 exit(1);
 435                         }
 436                         if (cp != NULL) {
 437                                 fwd.listen_port = a2port(cp);
 438                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 439                         } else {
 440                                 fwd.listen_port = a2port(fwd.listen_host);
 441                                 fwd.listen_host = "";
 442                         }
 443
 444                         if (fwd.listen_port == 0) {
 445                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 446                                     optarg);
 447                                 exit(1);
 448                         }
 449                         add_local_forward(&options, &fwd);
 450                         xfree(p);
 451                         break;
 452
 453                 case 'C':
 454                         options.compression = 1;
 455                         break;
 456                 case 'N':
 457                         no_shell_flag = 1;
 458                         no_tty_flag = 1;
 459                         break;
 460                 case 'T':
 461                         no_tty_flag = 1;
 462                         break;
 463                 case 'o':
 464                         dummy = 1;
 465                         line = xstrdup(optarg);
 466                         if (process_config_line(&options, host ? host : "",
 467                             line, "command-line", 0, &dummy) != 0)
 468                                 exit(1);
 469                         xfree(line);
 470                         break;
 471                 case 's':
 472                         subsystem_flag = 1;
 473                         break;
 474                 case 'S':
 475                         if (options.control_path != NULL)
 476                                 free(options.control_path);
 477                         options.control_path = xstrdup(optarg);
 478                         break;
 479                 case 'b':
 480                         options.bind_address = optarg;
 481                         break;
 482                 case 'F':
 483                         config = optarg;
 484                         break;
 485                 default:
 486                         usage();
 487                 }
 488         }
 489
 490         ac -= optind;
 491         av += optind;
 492
 493         if (ac > 0 && !host && **av != '-') {
 494                 if (strrchr(*av, '@')) {
 495                         p = xstrdup(*av);
 496                         cp = strrchr(p, '@');
 497                         if (cp == NULL || cp == p)
 498                                 usage();
 499                         options.user = p;
 500                         *cp = '\0';
 501                         host = ++cp;
 502                 } else
 503                         host = *av;
 504                 if (ac > 1) {
 505                         optind = optreset = 1;
 506                         goto again;
 507                 }
 508                 ac--, av++;
 509         }
 510
 511         /* Check that we got a host name. */
 512         if (!host)
 513                 usage();
 514
 515         SSLeay_add_all_algorithms();
 516         ERR_load_crypto_strings();
 517
 518         /* Initialize the command to execute on remote host. */
 519         buffer_init(&command);
 520
 521         /*
 522          * Save the command to execute on the remote host in a buffer. There
 523          * is no limit on the length of the command, except by the maximum
 524          * packet size.  Also sets the tty flag if there is no command.
 525          */
 526         if (!ac) {
 527                 /* No command specified - execute shell on a tty. */
 528                 tty_flag = 1;
 529                 if (subsystem_flag) {
 530                         fprintf(stderr,
 531                             "You must specify a subsystem to invoke.\n");
 532                         usage();
 533                 }
 534         } else {
 535                 /* A command has been specified.  Store it into the buffer. */
 536                 for (i = 0; i < ac; i++) {
 537                         if (i)
 538                                 buffer_append(&command, " ", 1);
 539                         buffer_append(&command, av[i], strlen(av[i]));
 540                 }
 541         }
 542
 543         /* Cannot fork to background if no command. */
 544         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 545                 fatal("Cannot fork into background without a command to execute.");
 546
 547         /* Allocate a tty by default if no command specified. */
 548         if (buffer_len(&command) == 0)
 549                 tty_flag = 1;
 550
 551         /* Force no tty */
 552         if (no_tty_flag)
 553                 tty_flag = 0;
 554         /* Do not allocate a tty if stdin is not a tty. */
 555         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 556                 if (tty_flag)
 557                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 558                 tty_flag = 0;
 559         }
 560
 561         /*
 562          * Initialize "log" output.  Since we are the client all output
 563          * actually goes to stderr.
 564          */
 565         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 566             SYSLOG_FACILITY_USER, 1);
 567
 568         /*
 569          * Read per-user configuration file.  Ignore the system wide config
 570          * file if the user specifies a config file on the command line.
 571          */
 572         if (config != NULL) {
 573                 if (!read_config_file(config, host, &options, 0))
 574                         fatal("Can't open user config file %.100s: "
 575                             "%.100s", config, strerror(errno));
 576         } else  {
 577                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 578                     _PATH_SSH_USER_CONFFILE);
 579                 (void)read_config_file(buf, host, &options, 1);
 580
 581                 /* Read systemwide configuration file after use config. */
 582                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 583                     &options, 0);
 584         }
 585
 586         /* Fill configuration defaults. */
 587         fill_default_options(&options);
 588
 589         channel_set_af(options.address_family);
 590
 591         /* reinit */
 592         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 593
 594         seed_rng();
 595
 596         if (options.user == NULL)
 597                 options.user = xstrdup(pw->pw_name);
 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                 snprintf(buf, sizeof(buf), "%d", options.port);
 615                 cp = tilde_expand_filename(options.control_path,
 616                     original_real_uid);
 617                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 618                     "r", options.user, (char *)NULL);
 619                 xfree(cp);
 620         }
 621         if (mux_command != 0 && options.control_path == NULL)
 622                 fatal("No ControlPath specified for \"-O\" command");
 623         if (options.control_path != NULL)
 624                 control_client(options.control_path);
 625
 626         /* Open a connection to the remote host. */
 627         if (ssh_connect(host, &hostaddr, options.port,
 628             options.address_family, options.connection_attempts,
 629 #ifdef HAVE_CYGWIN
 630             options.use_privileged_port,
 631 #else
 632             original_effective_uid == 0 && options.use_privileged_port,
 633 #endif
 634             options.proxy_command) != 0)
 635                 exit(1);
 636
 637         /*
 638          * If we successfully made the connection, load the host private key
 639          * in case we will need it later for combined rsa-rhosts
 640          * authentication. This must be done before releasing extra
 641          * privileges, because the file is only readable by root.
 642          * If we cannot access the private keys, load the public keys
 643          * instead and try to execute the ssh-keysign helper instead.
 644          */
 645         sensitive_data.nkeys = 0;
 646         sensitive_data.keys = NULL;
 647         sensitive_data.external_keysign = 0;
 648         if (options.rhosts_rsa_authentication ||
 649             options.hostbased_authentication) {
 650                 sensitive_data.nkeys = 3;
 651                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 652                     sizeof(Key));
 653
 654                 PRIV_START;
 655                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 656                     _PATH_HOST_KEY_FILE, "", NULL);
 657                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 658                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 659                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 660                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 661                 PRIV_END;
 662
 663                 if (options.hostbased_authentication == 1 &&
 664                     sensitive_data.keys[0] == NULL &&
 665                     sensitive_data.keys[1] == NULL &&
 666                     sensitive_data.keys[2] == NULL) {
 667                         sensitive_data.keys[1] = key_load_public(
 668                             _PATH_HOST_DSA_KEY_FILE, NULL);
 669                         sensitive_data.keys[2] = key_load_public(
 670                             _PATH_HOST_RSA_KEY_FILE, NULL);
 671                         sensitive_data.external_keysign = 1;
 672                 }
 673         }
 674         /*
 675          * Get rid of any extra privileges that we may have.  We will no
 676          * longer need them.  Also, extra privileges could make it very hard
 677          * to read identity files and other non-world-readable files from the
 678          * user's home directory if it happens to be on a NFS volume where
 679          * root is mapped to nobody.
 680          */
 681         if (original_effective_uid == 0) {
 682                 PRIV_START;
 683                 permanently_set_uid(pw);
 684         }
 685
 686         /*
 687          * Now that we are back to our own permissions, create ~/.ssh
 688          * directory if it doesn\'t already exist.
 689          */
 690         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 691         if (stat(buf, &st) < 0)
 692                 if (mkdir(buf, 0700) < 0)
 693                         error("Could not create directory '%.200s'.", buf);
 694
 695         /* load options.identity_files */
 696         load_public_identity_files();
 697
 698         /* Expand ~ in known host file names. */
 699         /* XXX mem-leaks: */
 700         options.system_hostfile =
 701             tilde_expand_filename(options.system_hostfile, original_real_uid);
 702         options.user_hostfile =
 703             tilde_expand_filename(options.user_hostfile, original_real_uid);
 704         options.system_hostfile2 =
 705             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 706         options.user_hostfile2 =
 707             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 708
 709         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 710
 711         /* Log into the remote system.  This never returns if the login fails. */
 712         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 713
 714         /* We no longer need the private host keys.  Clear them now. */
 715         if (sensitive_data.nkeys != 0) {
 716                 for (i = 0; i < sensitive_data.nkeys; i++) {
 717                         if (sensitive_data.keys[i] != NULL) {
 718                                 /* Destroys contents safely */
 719                                 debug3("clear hostkey %d", i);
 720                                 key_free(sensitive_data.keys[i]);
 721                                 sensitive_data.keys[i] = NULL;
 722                         }
 723                 }
 724                 xfree(sensitive_data.keys);
 725         }
 726         for (i = 0; i < options.num_identity_files; i++) {
 727                 if (options.identity_files[i]) {
 728                         xfree(options.identity_files[i]);
 729                         options.identity_files[i] = NULL;
 730                 }
 731                 if (options.identity_keys[i]) {
 732                         key_free(options.identity_keys[i]);
 733                         options.identity_keys[i] = NULL;
 734                 }
 735         }
 736
 737         exit_status = compat20 ? ssh_session2() : ssh_session();
 738         packet_close();
 739
 740         if (options.control_path != NULL && control_fd != -1)
 741                 unlink(options.control_path);
 742
 743         /*
 744          * Send SIGHUP to proxy command if used. We don't wait() in
 745          * case it hangs and instead rely on init to reap the child
 746          */
 747         if (proxy_command_pid > 1)
 748                 kill(proxy_command_pid, SIGHUP);
 749
 750         return exit_status;
 751 }
 752
 753 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
 754
 755 static void
 756 x11_get_proto(char **_proto, char **_data)
 757 {
 758         char cmd[1024];
 759         char line[512];
 760         char xdisplay[512];
 761         static char proto[512], data[512];
 762         FILE *f;
 763         int got_data = 0, generated = 0, do_unlink = 0, i;
 764         char *display, *xauthdir, *xauthfile;
 765         struct stat st;
 766
 767         xauthdir = xauthfile = NULL;
 768         *_proto = proto;
 769         *_data = data;
 770         proto[0] = data[0] = '\0';
 771
 772         if (!options.xauth_location ||
 773             (stat(options.xauth_location, &st) == -1)) {
 774                 debug("No xauth program.");
 775         } else {
 776                 if ((display = getenv("DISPLAY")) == NULL) {
 777                         debug("x11_get_proto: DISPLAY not set");
 778                         return;
 779                 }
 780                 /*
 781                  * Handle FamilyLocal case where $DISPLAY does
 782                  * not match an authorization entry.  For this we
 783                  * just try "xauth list unix:displaynum.screennum".
 784                  * XXX: "localhost" match to determine FamilyLocal
 785                  *      is not perfect.
 786                  */
 787                 if (strncmp(display, "localhost:", 10) == 0) {
 788                         snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
 789                             display + 10);
 790                         display = xdisplay;
 791                 }
 792                 if (options.forward_x11_trusted == 0) {
 793                         xauthdir = xmalloc(MAXPATHLEN);
 794                         xauthfile = xmalloc(MAXPATHLEN);
 795                         strlcpy(xauthdir, "/tmp/ssh-XXXXXXXXXX", MAXPATHLEN);
 796                         if (mkdtemp(xauthdir) != NULL) {
 797                                 do_unlink = 1;
 798                                 snprintf(xauthfile, MAXPATHLEN, "%s/xauthfile",
 799                                     xauthdir);
 800                                 snprintf(cmd, sizeof(cmd),
 801                                     "%s -f %s generate %s " SSH_X11_PROTO
 802                                     " untrusted timeout 1200 2>" _PATH_DEVNULL,
 803                                     options.xauth_location, xauthfile, display);
 804                                 debug2("x11_get_proto: %s", cmd);
 805                                 if (system(cmd) == 0)
 806                                         generated = 1;
 807                         }
 808                 }
 809                 snprintf(cmd, sizeof(cmd),
 810                     "%s %s%s list %s . 2>" _PATH_DEVNULL,
 811                     options.xauth_location,
 812                     generated ? "-f " : "" ,
 813                     generated ? xauthfile : "",
 814                     display);
 815                 debug2("x11_get_proto: %s", cmd);
 816                 f = popen(cmd, "r");
 817                 if (f && fgets(line, sizeof(line), f) &&
 818                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 819                         got_data = 1;
 820                 if (f)
 821                         pclose(f);
 822         }
 823
 824         if (do_unlink) {
 825                 unlink(xauthfile);
 826                 rmdir(xauthdir);
 827         }
 828         if (xauthdir)
 829                 xfree(xauthdir);
 830         if (xauthfile)
 831                 xfree(xauthfile);
 832
 833         /*
 834          * If we didn't get authentication data, just make up some
 835          * data.  The forwarding code will check the validity of the
 836          * response anyway, and substitute this data.  The X11
 837          * server, however, will ignore this fake data and use
 838          * whatever authentication mechanisms it was using otherwise
 839          * for the local connection.
 840          */
 841         if (!got_data) {
 842                 u_int32_t rnd = 0;
 843
 844                 logit("Warning: No xauth data; "
 845                     "using fake authentication data for X11 forwarding.");
 846                 strlcpy(proto, SSH_X11_PROTO, sizeof proto);
 847                 for (i = 0; i < 16; i++) {
 848                         if (i % 4 == 0)
 849                                 rnd = arc4random();
 850                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
 851                             rnd & 0xff);
 852                         rnd >>= 8;
 853                 }
 854         }
 855 }
 856
 857 static void
 858 ssh_init_forwarding(void)
 859 {
 860         int success = 0;
 861         int i;
 862
 863         /* Initiate local TCP/IP port forwardings. */
 864         for (i = 0; i < options.num_local_forwards; i++) {
 865                 debug("Local connections to %.200s:%d forwarded to remote "
 866                     "address %.200s:%d",
 867                     (options.local_forwards[i].listen_host == NULL) ?
 868                     (options.gateway_ports ? "*" : "LOCALHOST") :
 869                     options.local_forwards[i].listen_host,
 870                     options.local_forwards[i].listen_port,
 871                     options.local_forwards[i].connect_host,
 872                     options.local_forwards[i].connect_port);
 873                 success += channel_setup_local_fwd_listener(
 874                     options.local_forwards[i].listen_host,
 875                     options.local_forwards[i].listen_port,
 876                     options.local_forwards[i].connect_host,
 877                     options.local_forwards[i].connect_port,
 878                     options.gateway_ports);
 879         }
 880         if (i > 0 && success == 0)
 881                 error("Could not request local forwarding.");
 882
 883         /* Initiate remote TCP/IP port forwardings. */
 884         for (i = 0; i < options.num_remote_forwards; i++) {
 885                 debug("Remote connections from %.200s:%d forwarded to "
 886                     "local address %.200s:%d",
 887                     (options.remote_forwards[i].listen_host == NULL) ?
 888                     (options.gateway_ports ? "*" : "LOCALHOST") :
 889                     options.remote_forwards[i].listen_host,
 890                     options.remote_forwards[i].listen_port,
 891                     options.remote_forwards[i].connect_host,
 892                     options.remote_forwards[i].connect_port);
 893                 channel_request_remote_forwarding(
 894                     options.remote_forwards[i].listen_host,
 895                     options.remote_forwards[i].listen_port,
 896                     options.remote_forwards[i].connect_host,
 897                     options.remote_forwards[i].connect_port);
 898         }
 899 }
 900
 901 static void
 902 check_agent_present(void)
 903 {
 904         if (options.forward_agent) {
 905                 /* Clear agent forwarding if we don\'t have an agent. */
 906                 if (!ssh_agent_present())
 907                         options.forward_agent = 0;
 908         }
 909 }
 910
 911 static int
 912 ssh_session(void)
 913 {
 914         int type;
 915         int interactive = 0;
 916         int have_tty = 0;
 917         struct winsize ws;
 918         char *cp;
 919
 920         /* Enable compression if requested. */
 921         if (options.compression) {
 922                 debug("Requesting compression at level %d.", options.compression_level);
 923
 924                 if (options.compression_level < 1 || options.compression_level > 9)
 925                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 926
 927                 /* Send the request. */
 928                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 929                 packet_put_int(options.compression_level);
 930                 packet_send();
 931                 packet_write_wait();
 932                 type = packet_read();
 933                 if (type == SSH_SMSG_SUCCESS)
 934                         packet_start_compression(options.compression_level);
 935                 else if (type == SSH_SMSG_FAILURE)
 936                         logit("Warning: Remote host refused compression.");
 937                 else
 938                         packet_disconnect("Protocol error waiting for compression response.");
 939         }
 940         /* Allocate a pseudo tty if appropriate. */
 941         if (tty_flag) {
 942                 debug("Requesting pty.");
 943
 944                 /* Start the packet. */
 945                 packet_start(SSH_CMSG_REQUEST_PTY);
 946
 947                 /* Store TERM in the packet.  There is no limit on the
 948                    length of the string. */
 949                 cp = getenv("TERM");
 950                 if (!cp)
 951                         cp = "";
 952                 packet_put_cstring(cp);
 953
 954                 /* Store window size in the packet. */
 955                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 956                         memset(&ws, 0, sizeof(ws));
 957                 packet_put_int(ws.ws_row);
 958                 packet_put_int(ws.ws_col);
 959                 packet_put_int(ws.ws_xpixel);
 960                 packet_put_int(ws.ws_ypixel);
 961
 962                 /* Store tty modes in the packet. */
 963                 tty_make_modes(fileno(stdin), NULL);
 964
 965                 /* Send the packet, and wait for it to leave. */
 966                 packet_send();
 967                 packet_write_wait();
 968
 969                 /* Read response from the server. */
 970                 type = packet_read();
 971                 if (type == SSH_SMSG_SUCCESS) {
 972                         interactive = 1;
 973                         have_tty = 1;
 974                 } else if (type == SSH_SMSG_FAILURE)
 975                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 976                 else
 977                         packet_disconnect("Protocol error waiting for pty request response.");
 978         }
 979         /* Request X11 forwarding if enabled and DISPLAY is set. */
 980         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 981                 char *proto, *data;
 982                 /* Get reasonable local authentication information. */
 983                 x11_get_proto(&proto, &data);
 984                 /* Request forwarding with authentication spoofing. */
 985                 debug("Requesting X11 forwarding with authentication spoofing.");
 986                 x11_request_forwarding_with_spoofing(0, proto, data);
 987
 988                 /* Read response from the server. */
 989                 type = packet_read();
 990                 if (type == SSH_SMSG_SUCCESS) {
 991                         interactive = 1;
 992                 } else if (type == SSH_SMSG_FAILURE) {
 993                         logit("Warning: Remote host denied X11 forwarding.");
 994                 } else {
 995                         packet_disconnect("Protocol error waiting for X11 forwarding");
 996                 }
 997         }
 998         /* Tell the packet module whether this is an interactive session. */
 999         packet_set_interactive(interactive);
1000
1001         /* Request authentication agent forwarding if appropriate. */
1002         check_agent_present();
1003
1004         if (options.forward_agent) {
1005                 debug("Requesting authentication agent forwarding.");
1006                 auth_request_forwarding();
1007
1008                 /* Read response from the server. */
1009                 type = packet_read();
1010                 packet_check_eom();
1011                 if (type != SSH_SMSG_SUCCESS)
1012                         logit("Warning: Remote host denied authentication agent forwarding.");
1013         }
1014
1015         /* Initiate port forwardings. */
1016         ssh_init_forwarding();
1017
1018         /* If requested, let ssh continue in the background. */
1019         if (fork_after_authentication_flag)
1020                 if (daemon(1, 1) < 0)
1021                         fatal("daemon() failed: %.200s", strerror(errno));
1022
1023         /*
1024          * If a command was specified on the command line, execute the
1025          * command now. Otherwise request the server to start a shell.
1026          */
1027         if (buffer_len(&command) > 0) {
1028                 int len = buffer_len(&command);
1029                 if (len > 900)
1030                         len = 900;
1031                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1032                 packet_start(SSH_CMSG_EXEC_CMD);
1033                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1034                 packet_send();
1035                 packet_write_wait();
1036         } else {
1037                 debug("Requesting shell.");
1038                 packet_start(SSH_CMSG_EXEC_SHELL);
1039                 packet_send();
1040                 packet_write_wait();
1041         }
1042
1043         /* Enter the interactive session. */
1044         return client_loop(have_tty, tty_flag ?
1045             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1046 }
1047
1048 static void
1049 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1050 {
1051         int id, len;
1052
1053         id = packet_get_int();
1054         len = buffer_len(&command);
1055         if (len > 900)
1056                 len = 900;
1057         packet_check_eom();
1058         if (type == SSH2_MSG_CHANNEL_FAILURE)
1059                 fatal("Request for subsystem '%.*s' failed on channel %d",
1060                     len, (u_char *)buffer_ptr(&command), id);
1061 }
1062
1063 void
1064 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1065 {
1066         int i;
1067
1068         i = client_global_request_id++;
1069         if (i >= options.num_remote_forwards)
1070                 return;
1071         debug("remote forward %s for: listen %d, connect %s:%d",
1072             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1073             options.remote_forwards[i].listen_port,
1074             options.remote_forwards[i].connect_host,
1075             options.remote_forwards[i].connect_port);
1076         if (type == SSH2_MSG_REQUEST_FAILURE)
1077                 logit("Warning: remote port forwarding failed for listen "
1078                     "port %d", options.remote_forwards[i].listen_port);
1079 }
1080
1081 static void
1082 ssh_control_listener(void)
1083 {
1084         struct sockaddr_un addr;
1085         mode_t old_umask;
1086         int addr_len;
1087
1088         if (options.control_path == NULL ||
1089             options.control_master == SSHCTL_MASTER_NO)
1090                 return;
1091
1092         debug("setting up multiplex master socket");
1093
1094         memset(&addr, '\0', sizeof(addr));
1095         addr.sun_family = AF_UNIX;
1096         addr_len = offsetof(struct sockaddr_un, sun_path) +
1097             strlen(options.control_path) + 1;
1098
1099         if (strlcpy(addr.sun_path, options.control_path,
1100             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1101                 fatal("ControlPath too long");
1102
1103         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1104                 fatal("%s socket(): %s\n", __func__, strerror(errno));
1105
1106         old_umask = umask(0177);
1107         if (bind(control_fd, (struct sockaddr*)&addr, addr_len) == -1) {
1108                 control_fd = -1;
1109                 if (errno == EINVAL || errno == EADDRINUSE)
1110                         fatal("ControlSocket %s already exists",
1111                             options.control_path);
1112                 else
1113                         fatal("%s bind(): %s\n", __func__, strerror(errno));
1114         }
1115         umask(old_umask);
1116
1117         if (listen(control_fd, 64) == -1)
1118                 fatal("%s listen(): %s\n", __func__, strerror(errno));
1119
1120         set_nonblock(control_fd);
1121 }
1122
1123 /* request pty/x11/agent/tcpfwd/shell for channel */
1124 static void
1125 ssh_session2_setup(int id, void *arg)
1126 {
1127         extern char **environ;
1128
1129         int interactive = tty_flag;
1130         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
1131                 char *proto, *data;
1132                 /* Get reasonable local authentication information. */
1133                 x11_get_proto(&proto, &data);
1134                 /* Request forwarding with authentication spoofing. */
1135                 debug("Requesting X11 forwarding with authentication spoofing.");
1136                 x11_request_forwarding_with_spoofing(id, proto, data);
1137                 interactive = 1;
1138                 /* XXX wait for reply */
1139         }
1140
1141         check_agent_present();
1142         if (options.forward_agent) {
1143                 debug("Requesting authentication agent forwarding.");
1144                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1145                 packet_send();
1146         }
1147
1148         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1149             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1150
1151         packet_set_interactive(interactive);
1152 }
1153
1154 /* open new channel for a session */
1155 static int
1156 ssh_session2_open(void)
1157 {
1158         Channel *c;
1159         int window, packetmax, in, out, err;
1160
1161         if (stdin_null_flag) {
1162                 in = open(_PATH_DEVNULL, O_RDONLY);
1163         } else {
1164                 in = dup(STDIN_FILENO);
1165         }
1166         out = dup(STDOUT_FILENO);
1167         err = dup(STDERR_FILENO);
1168
1169         if (in < 0 || out < 0 || err < 0)
1170                 fatal("dup() in/out/err failed");
1171
1172         /* enable nonblocking unless tty */
1173         if (!isatty(in))
1174                 set_nonblock(in);
1175         if (!isatty(out))
1176                 set_nonblock(out);
1177         if (!isatty(err))
1178                 set_nonblock(err);
1179
1180         window = CHAN_SES_WINDOW_DEFAULT;
1181         packetmax = CHAN_SES_PACKET_DEFAULT;
1182         if (tty_flag) {
1183                 window >>= 1;
1184                 packetmax >>= 1;
1185         }
1186         c = channel_new(
1187             "session", SSH_CHANNEL_OPENING, in, out, err,
1188             window, packetmax, CHAN_EXTENDED_WRITE,
1189             "client-session", /*nonblock*/0);
1190
1191         debug3("ssh_session2_open: channel_new: %d", c->self);
1192
1193         channel_send_open(c->self);
1194         if (!no_shell_flag)
1195                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1196
1197         return c->self;
1198 }
1199
1200 static int
1201 ssh_session2(void)
1202 {
1203         int id = -1;
1204
1205         /* XXX should be pre-session */
1206         ssh_init_forwarding();
1207         ssh_control_listener();
1208
1209         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1210                 id = ssh_session2_open();
1211
1212         /* If requested, let ssh continue in the background. */
1213         if (fork_after_authentication_flag)
1214                 if (daemon(1, 1) < 0)
1215                         fatal("daemon() failed: %.200s", strerror(errno));
1216
1217         return client_loop(tty_flag, tty_flag ?
1218             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1219 }
1220
1221 static void
1222 load_public_identity_files(void)
1223 {
1224         char *filename;
1225         int i = 0;
1226         Key *public;
1227 #ifdef SMARTCARD
1228         Key **keys;
1229
1230         if (options.smartcard_device != NULL &&
1231             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1232             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1233                 int count = 0;
1234                 for (i = 0; keys[i] != NULL; i++) {
1235                         count++;
1236                         memmove(&options.identity_files[1], &options.identity_files[0],
1237                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1238                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1239                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1240                         options.num_identity_files++;
1241                         options.identity_keys[0] = keys[i];
1242                         options.identity_files[0] = sc_get_key_label(keys[i]);
1243                 }
1244                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1245                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1246                 i = count;
1247                 xfree(keys);
1248         }
1249 #endif /* SMARTCARD */
1250         for (; i < options.num_identity_files; i++) {
1251                 filename = tilde_expand_filename(options.identity_files[i],
1252                     original_real_uid);
1253                 public = key_load_public(filename, NULL);
1254                 debug("identity file %s type %d", filename,
1255                     public ? public->type : -1);
1256                 xfree(options.identity_files[i]);
1257                 options.identity_files[i] = filename;
1258                 options.identity_keys[i] = public;
1259         }
1260 }
1261
1262 static void
1263 control_client_sighandler(int signo)
1264 {
1265         control_client_terminate = signo;
1266 }
1267
1268 static void
1269 control_client_sigrelay(int signo)
1270 {
1271         if (control_server_pid > 1)
1272                 kill(control_server_pid, signo);
1273 }
1274
1275 static int
1276 env_permitted(char *env)
1277 {
1278         int i;
1279         char name[1024], *cp;
1280
1281         strlcpy(name, env, sizeof(name));
1282         if ((cp = strchr(name, '=')) == NULL)
1283                 return (0);
1284
1285         *cp = '\0';
1286
1287         for (i = 0; i < options.num_send_env; i++)
1288                 if (match_pattern(name, options.send_env[i]))
1289                         return (1);
1290
1291         return (0);
1292 }
1293
1294 static void
1295 control_client(const char *path)
1296 {
1297         struct sockaddr_un addr;
1298         int i, r, fd, sock, exitval, num_env, addr_len;
1299         Buffer m;
1300         char *term;
1301         extern char **environ;
1302         u_int  flags;
1303
1304         if (mux_command == 0)
1305                 mux_command = SSHMUX_COMMAND_OPEN;
1306
1307         switch (options.control_master) {
1308         case SSHCTL_MASTER_AUTO:
1309         case SSHCTL_MASTER_AUTO_ASK:
1310                 debug("auto-mux: Trying existing master");
1311                 /* FALLTHROUGH */
1312         case SSHCTL_MASTER_NO:
1313                 break;
1314         default:
1315                 return;
1316         }
1317
1318         memset(&addr, '\0', sizeof(addr));
1319         addr.sun_family = AF_UNIX;
1320         addr_len = offsetof(struct sockaddr_un, sun_path) +
1321             strlen(path) + 1;
1322
1323         if (strlcpy(addr.sun_path, path,
1324             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1325                 fatal("ControlPath too long");
1326
1327         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1328                 fatal("%s socket(): %s", __func__, strerror(errno));
1329
1330         if (connect(sock, (struct sockaddr*)&addr, addr_len) == -1) {
1331                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1332                         fatal("Control socket connect(%.100s): %s", path,
1333                             strerror(errno));
1334                 }
1335                 if (errno == ENOENT)
1336                         debug("Control socket \"%.100s\" does not exist", path);
1337                 else {
1338                         error("Control socket connect(%.100s): %s", path,
1339                             strerror(errno));
1340                 }
1341                 close(sock);
1342                 return;
1343         }
1344
1345         if (stdin_null_flag) {
1346                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1347                         fatal("open(/dev/null): %s", strerror(errno));
1348                 if (dup2(fd, STDIN_FILENO) == -1)
1349                         fatal("dup2: %s", strerror(errno));
1350                 if (fd > STDERR_FILENO)
1351                         close(fd);
1352         }
1353
1354         if ((term = getenv("TERM")) == NULL)
1355                 term = "";
1356
1357         flags = 0;
1358         if (tty_flag)
1359                 flags |= SSHMUX_FLAG_TTY;
1360         if (subsystem_flag)
1361                 flags |= SSHMUX_FLAG_SUBSYS;
1362
1363         buffer_init(&m);
1364
1365         /* Send our command to server */
1366         buffer_put_int(&m, mux_command);
1367         buffer_put_int(&m, flags);
1368         if (ssh_msg_send(sock, /* version */1, &m) == -1)
1369                 fatal("%s: msg_send", __func__);
1370         buffer_clear(&m);
1371
1372         /* Get authorisation status and PID of controlee */
1373         if (ssh_msg_recv(sock, &m) == -1)
1374                 fatal("%s: msg_recv", __func__);
1375         if (buffer_get_char(&m) != 1)
1376                 fatal("%s: wrong version", __func__);
1377         if (buffer_get_int(&m) != 1)
1378                 fatal("Connection to master denied");
1379         control_server_pid = buffer_get_int(&m);
1380
1381         buffer_clear(&m);
1382
1383         switch (mux_command) {
1384         case SSHMUX_COMMAND_ALIVE_CHECK:
1385                 fprintf(stderr, "Master running (pid=%d)\r\n",
1386                     control_server_pid);
1387                 exit(0);
1388         case SSHMUX_COMMAND_TERMINATE:
1389                 fprintf(stderr, "Exit request sent.\r\n");
1390                 exit(0);
1391         case SSHMUX_COMMAND_OPEN:
1392                 /* continue below */
1393                 break;
1394         default:
1395                 fatal("silly mux_command %d", mux_command);
1396         }
1397
1398         /* SSHMUX_COMMAND_OPEN */
1399         buffer_put_cstring(&m, term);
1400         buffer_append(&command, "\0", 1);
1401         buffer_put_cstring(&m, buffer_ptr(&command));
1402
1403         if (options.num_send_env == 0 || environ == NULL) {
1404                 buffer_put_int(&m, 0);
1405         } else {
1406                 /* Pass environment */
1407                 num_env = 0;
1408                 for (i = 0; environ[i] != NULL; i++)
1409                         if (env_permitted(environ[i]))
1410                                 num_env++; /* Count */
1411
1412                 buffer_put_int(&m, num_env);
1413
1414                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1415                         if (env_permitted(environ[i])) {
1416                                 num_env--;
1417                                 buffer_put_cstring(&m, environ[i]);
1418                         }
1419         }
1420
1421         if (ssh_msg_send(sock, /* version */1, &m) == -1)
1422                 fatal("%s: msg_send", __func__);
1423
1424         mm_send_fd(sock, STDIN_FILENO);
1425         mm_send_fd(sock, STDOUT_FILENO);
1426         mm_send_fd(sock, STDERR_FILENO);
1427
1428         /* Wait for reply, so master has a chance to gather ttymodes */
1429         buffer_clear(&m);
1430         if (ssh_msg_recv(sock, &m) == -1)
1431                 fatal("%s: msg_recv", __func__);
1432         if (buffer_get_char(&m) != 1)
1433                 fatal("%s: wrong version", __func__);
1434         buffer_free(&m);
1435
1436         signal(SIGHUP, control_client_sighandler);
1437         signal(SIGINT, control_client_sighandler);
1438         signal(SIGTERM, control_client_sighandler);
1439         signal(SIGWINCH, control_client_sigrelay);
1440
1441         if (tty_flag)
1442                 enter_raw_mode();
1443
1444         /* Stick around until the controlee closes the client_fd */
1445         exitval = 0;
1446         for (;!control_client_terminate;) {
1447                 r = read(sock, &exitval, sizeof(exitval));
1448                 if (r == 0) {
1449                         debug2("Received EOF from master");
1450                         break;
1451                 }
1452                 if (r > 0)
1453                         debug2("Received exit status from master %d", exitval);
1454                 if (r == -1 && errno != EINTR)
1455                         fatal("%s: read %s", __func__, strerror(errno));
1456         }
1457
1458         if (control_client_terminate)
1459                 debug2("Exiting on signal %d", control_client_terminate);
1460
1461         close(sock);
1462
1463         leave_raw_mode();
1464
1465         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1466                 fprintf(stderr, "Connection to master closed.\r\n");
1467
1468         exit(exitval);
1469 }