openssh/ssh.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * Ssh client program.  This program can be used to log into a remote machine.
   6  * The software supports strong authentication, encryption, and forwarding
   7  * of X11, TCP/IP, and authentication connections.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  16  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  17  *
  18  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  19  * in Canada (German citizen).
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43 RCSID("$OpenBSD: ssh.c,v 1.249 2005/07/30 01:26:16 djm Exp $");
  44
  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         struct servent *sp;
 189         Forward fwd;
 190
 191         __progname = ssh_get_progname(av[0]);
 192         init_rng();
 193
 194         /*
 195          * Save the original real uid.  It will be needed later (uid-swapping
 196          * may clobber the real uid).
 197          */
 198         original_real_uid = getuid();
 199         original_effective_uid = geteuid();
 200
 201         /*
 202          * Use uid-swapping to give up root privileges for the duration of
 203          * option processing.  We will re-instantiate the rights when we are
 204          * ready to create the privileged port, and will permanently drop
 205          * them when the port has been created (actually, when the connection
 206          * has been made, as we may need to create the port several times).
 207          */
 208         PRIV_END;
 209
 210 #ifdef HAVE_SETRLIMIT
 211         /* If we are installed setuid root be careful to not drop core. */
 212         if (original_real_uid != original_effective_uid) {
 213                 struct rlimit rlim;
 214                 rlim.rlim_cur = rlim.rlim_max = 0;
 215                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 216                         fatal("setrlimit failed: %.100s", strerror(errno));
 217         }
 218 #endif
 219         /* Get user data. */
 220         pw = getpwuid(original_real_uid);
 221         if (!pw) {
 222                 logit("You don't exist, go away!");
 223                 exit(1);
 224         }
 225         /* Take a copy of the returned structure. */
 226         pw = pwcopy(pw);
 227
 228         /*
 229          * Set our umask to something reasonable, as some files are created
 230          * with the default umask.  This will make them world-readable but
 231          * writable only by the owner, which is ok for all files for which we
 232          * don't set the modes explicitly.
 233          */
 234         umask(022);
 235
 236         /* Initialize option structure to indicate that no values have been set. */
 237         initialize_options(&options);
 238
 239         /* Parse command-line arguments. */
 240         host = NULL;
 241
 242 again:
 243         while ((opt = getopt(ac, av,
 244             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:MNO:PR:S:TVXY")) != -1) {
 245                 switch (opt) {
 246                 case '1':
 247                         options.protocol = SSH_PROTO_1;
 248                         break;
 249                 case '2':
 250                         options.protocol = SSH_PROTO_2;
 251                         break;
 252                 case '4':
 253                         options.address_family = AF_INET;
 254                         break;
 255                 case '6':
 256                         options.address_family = AF_INET6;
 257                         break;
 258                 case 'n':
 259                         stdin_null_flag = 1;
 260                         break;
 261                 case 'f':
 262                         fork_after_authentication_flag = 1;
 263                         stdin_null_flag = 1;
 264                         break;
 265                 case 'x':
 266                         options.forward_x11 = 0;
 267                         break;
 268                 case 'X':
 269                         options.forward_x11 = 1;
 270                         break;
 271                 case 'Y':
 272                         options.forward_x11 = 1;
 273                         options.forward_x11_trusted = 1;
 274                         break;
 275                 case 'g':
 276                         options.gateway_ports = 1;
 277                         break;
 278                 case 'O':
 279                         if (strcmp(optarg, "check") == 0)
 280                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 281                         else if (strcmp(optarg, "exit") == 0)
 282                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 283                         else
 284                                 fatal("Invalid multiplex command.");
 285                         break;
 286                 case 'P':       /* deprecated */
 287                         options.use_privileged_port = 0;
 288                         break;
 289                 case 'a':
 290                         options.forward_agent = 0;
 291                         break;
 292                 case 'A':
 293                         options.forward_agent = 1;
 294                         break;
 295                 case 'k':
 296                         options.gss_deleg_creds = 0;
 297                         break;
 298                 case 'i':
 299                         if (stat(optarg, &st) < 0) {
 300                                 fprintf(stderr, "Warning: Identity file %s "
 301                                     "not accessible: %s.\n", optarg,
 302                                     strerror(errno));
 303                                 break;
 304                         }
 305                         if (options.num_identity_files >=
 306                             SSH_MAX_IDENTITY_FILES)
 307                                 fatal("Too many identity files specified "
 308                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 309                         options.identity_files[options.num_identity_files++] =
 310                             xstrdup(optarg);
 311                         break;
 312                 case 'I':
 313 #ifdef SMARTCARD
 314                         options.smartcard_device = xstrdup(optarg);
 315 #else
 316                         fprintf(stderr, "no support for smartcards.\n");
 317 #endif
 318                         break;
 319                 case 't':
 320                         if (tty_flag)
 321                                 force_tty_flag = 1;
 322                         tty_flag = 1;
 323                         break;
 324                 case 'v':
 325                         if (debug_flag == 0) {
 326                                 debug_flag = 1;
 327                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 328                         } else {
 329                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 330                                         options.log_level++;
 331                                 break;
 332                         }
 333                         /* FALLTHROUGH */
 334                 case 'V':
 335                         fprintf(stderr, "%s, %s\n",
 336                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 337                         if (opt == 'V')
 338                                 exit(0);
 339                         break;
 340                 case 'q':
 341                         options.log_level = SYSLOG_LEVEL_QUIET;
 342                         break;
 343                 case 'e':
 344                         if (optarg[0] == '^' && optarg[2] == 0 &&
 345                             (u_char) optarg[1] >= 64 &&
 346                             (u_char) optarg[1] < 128)
 347                                 options.escape_char = (u_char) optarg[1] & 31;
 348                         else if (strlen(optarg) == 1)
 349                                 options.escape_char = (u_char) optarg[0];
 350                         else if (strcmp(optarg, "none") == 0)
 351                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 352                         else {
 353                                 fprintf(stderr, "Bad escape character '%s'.\n",
 354                                     optarg);
 355                                 exit(1);
 356                         }
 357                         break;
 358                 case 'c':
 359                         if (ciphers_valid(optarg)) {
 360                                 /* SSH2 only */
 361                                 options.ciphers = xstrdup(optarg);
 362                                 options.cipher = SSH_CIPHER_INVALID;
 363                         } else {
 364                                 /* SSH1 only */
 365                                 options.cipher = cipher_number(optarg);
 366                                 if (options.cipher == -1) {
 367                                         fprintf(stderr,
 368                                             "Unknown cipher type '%s'\n",
 369                                             optarg);
 370                                         exit(1);
 371                                 }
 372                                 if (options.cipher == SSH_CIPHER_3DES)
 373                                         options.ciphers = "3des-cbc";
 374                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 375                                         options.ciphers = "blowfish-cbc";
 376                                 else
 377                                         options.ciphers = (char *)-1;
 378                         }
 379                         break;
 380                 case 'm':
 381                         if (mac_valid(optarg))
 382                                 options.macs = xstrdup(optarg);
 383                         else {
 384                                 fprintf(stderr, "Unknown mac type '%s'\n",
 385                                     optarg);
 386                                 exit(1);
 387                         }
 388                         break;
 389                 case 'M':
 390                         if (options.control_master == SSHCTL_MASTER_YES)
 391                                 options.control_master = SSHCTL_MASTER_ASK;
 392                         else
 393                                 options.control_master = SSHCTL_MASTER_YES;
 394                         break;
 395                 case 'p':
 396                         options.port = a2port(optarg);
 397                         if (options.port == 0) {
 398                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 399                                 exit(1);
 400                         }
 401                         break;
 402                 case 'l':
 403                         options.user = optarg;
 404                         break;
 405
 406                 case 'L':
 407                         if (parse_forward(&fwd, optarg))
 408                                 add_local_forward(&options, &fwd);
 409                         else {
 410                                 fprintf(stderr,
 411                                     "Bad local forwarding specification '%s'\n",
 412                                     optarg);
 413                                 exit(1);
 414                         }
 415                         break;
 416
 417                 case 'R':
 418                         if (parse_forward(&fwd, optarg)) {
 419                                 add_remote_forward(&options, &fwd);
 420                         } else {
 421                                 fprintf(stderr,
 422                                     "Bad remote forwarding specification "
 423                                     "'%s'\n", optarg);
 424                                 exit(1);
 425                         }
 426                         break;
 427
 428                 case 'D':
 429                         cp = p = xstrdup(optarg);
 430                         memset(&fwd, '\0', sizeof(fwd));
 431                         fwd.connect_host = "socks";
 432                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 433                                 fprintf(stderr, "Bad dynamic forwarding "
 434                                     "specification '%.100s'\n", optarg);
 435                                 exit(1);
 436                         }
 437                         if (cp != NULL) {
 438                                 fwd.listen_port = a2port(cp);
 439                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 440                         } else {
 441                                 fwd.listen_port = a2port(fwd.listen_host);
 442                                 fwd.listen_host = NULL;
 443                         }
 444
 445                         if (fwd.listen_port == 0) {
 446                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 447                                     optarg);
 448                                 exit(1);
 449                         }
 450                         add_local_forward(&options, &fwd);
 451                         xfree(p);
 452                         break;
 453
 454                 case 'C':
 455                         options.compression = 1;
 456                         break;
 457                 case 'N':
 458                         no_shell_flag = 1;
 459                         no_tty_flag = 1;
 460                         break;
 461                 case 'T':
 462                         no_tty_flag = 1;
 463                         break;
 464                 case 'o':
 465                         dummy = 1;
 466                         line = xstrdup(optarg);
 467                         if (process_config_line(&options, host ? host : "",
 468                             line, "command-line", 0, &dummy) != 0)
 469                                 exit(1);
 470                         xfree(line);
 471                         break;
 472                 case 's':
 473                         subsystem_flag = 1;
 474                         break;
 475                 case 'S':
 476                         if (options.control_path != NULL)
 477                                 free(options.control_path);
 478                         options.control_path = xstrdup(optarg);
 479                         break;
 480                 case 'b':
 481                         options.bind_address = optarg;
 482                         break;
 483                 case 'F':
 484                         config = optarg;
 485                         break;
 486                 default:
 487                         usage();
 488                 }
 489         }
 490
 491         ac -= optind;
 492         av += optind;
 493
 494         if (ac > 0 && !host && **av != '-') {
 495                 if (strrchr(*av, '@')) {
 496                         p = xstrdup(*av);
 497                         cp = strrchr(p, '@');
 498                         if (cp == NULL || cp == p)
 499                                 usage();
 500                         options.user = p;
 501                         *cp = '\0';
 502                         host = ++cp;
 503                 } else
 504                         host = *av;
 505                 if (ac > 1) {
 506                         optind = optreset = 1;
 507                         goto again;
 508                 }
 509                 ac--, av++;
 510         }
 511
 512         /* Check that we got a host name. */
 513         if (!host)
 514                 usage();
 515
 516         SSLeay_add_all_algorithms();
 517         ERR_load_crypto_strings();
 518
 519         /* Initialize the command to execute on remote host. */
 520         buffer_init(&command);
 521
 522         /*
 523          * Save the command to execute on the remote host in a buffer. There
 524          * is no limit on the length of the command, except by the maximum
 525          * packet size.  Also sets the tty flag if there is no command.
 526          */
 527         if (!ac) {
 528                 /* No command specified - execute shell on a tty. */
 529                 tty_flag = 1;
 530                 if (subsystem_flag) {
 531                         fprintf(stderr,
 532                             "You must specify a subsystem to invoke.\n");
 533                         usage();
 534                 }
 535         } else {
 536                 /* A command has been specified.  Store it into the buffer. */
 537                 for (i = 0; i < ac; i++) {
 538                         if (i)
 539                                 buffer_append(&command, " ", 1);
 540                         buffer_append(&command, av[i], strlen(av[i]));
 541                 }
 542         }
 543
 544         /* Cannot fork to background if no command. */
 545         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 546                 fatal("Cannot fork into background without a command to execute.");
 547
 548         /* Allocate a tty by default if no command specified. */
 549         if (buffer_len(&command) == 0)
 550                 tty_flag = 1;
 551
 552         /* Force no tty */
 553         if (no_tty_flag)
 554                 tty_flag = 0;
 555         /* Do not allocate a tty if stdin is not a tty. */
 556         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 557                 if (tty_flag)
 558                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 559                 tty_flag = 0;
 560         }
 561
 562         /*
 563          * Initialize "log" output.  Since we are the client all output
 564          * actually goes to stderr.
 565          */
 566         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 567             SYSLOG_FACILITY_USER, 1);
 568
 569         /*
 570          * Read per-user configuration file.  Ignore the system wide config
 571          * file if the user specifies a config file on the command line.
 572          */
 573         if (config != NULL) {
 574                 if (!read_config_file(config, host, &options, 0))
 575                         fatal("Can't open user config file %.100s: "
 576                             "%.100s", config, strerror(errno));
 577         } else  {
 578             /*
 579              * Since the config file parsing code aborts if it sees
 580              * options it doesn't recognize, allow users to put
 581              * options specific to compile-time add-ons in alternate
 582              * config files so their primary config file will
 583              * interoperate SSH versions that don't support those
 584              * options.
 585              */
 586 #ifdef GSSAPI
 587                 snprintf(buf, sizeof buf, "%.100s/%.100s.gssapi", pw->pw_dir,
 588                     _PATH_SSH_USER_CONFFILE);
 589                 (void)read_config_file(buf, host, &options, 1);
 590 #ifdef GSI
 591                 snprintf(buf, sizeof buf, "%.100s/%.100s.gsi", pw->pw_dir,
 592                     _PATH_SSH_USER_CONFFILE);
 593                 (void)read_config_file(buf, host, &options, 1);
 594 #endif
 595 #if defined(KRB5)
 596                 snprintf(buf, sizeof buf, "%.100s/%.100s.krb", pw->pw_dir,
 597                     _PATH_SSH_USER_CONFFILE);
 598                 (void)read_config_file(buf, host, &options, 1);
 599 #endif
 600 #endif
 601                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 602                     _PATH_SSH_USER_CONFFILE);
 603                 (void)read_config_file(buf, host, &options, 1);
 604
 605                 /* Read systemwide configuration file after use config. */
 606                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 607                     &options, 0);
 608         }
 609
 610         /* Fill configuration defaults. */
 611         fill_default_options(&options);
 612
 613         channel_set_af(options.address_family);
 614
 615         /* reinit */
 616         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 617
 618         seed_rng();
 619
 620         if (options.user == NULL) {
 621                 options.user = xstrdup(pw->pw_name);
 622                 options.implicit = 1;
 623         }
 624         else options.implicit = 0;
 625
 626         if (options.hostname != NULL)
 627                 host = options.hostname;
 628
 629         /* force lowercase for hostkey matching */
 630         if (options.host_key_alias != NULL) {
 631                 for (p = options.host_key_alias; *p; p++)
 632                         if (isupper(*p))
 633                                 *p = tolower(*p);
 634         }
 635
 636         /* Get default port if port has not been set. */
 637         if (options.port == 0) {
 638                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 639                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 640         }
 641
 642         if (options.proxy_command != NULL &&
 643             strcmp(options.proxy_command, "none") == 0)
 644                 options.proxy_command = NULL;
 645         if (options.control_path != NULL &&
 646             strcmp(options.control_path, "none") == 0)
 647                 options.control_path = NULL;
 648
 649         if (options.control_path != NULL) {
 650                 snprintf(buf, sizeof(buf), "%d", options.port);
 651                 cp = tilde_expand_filename(options.control_path,
 652                     original_real_uid);
 653                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 654                     "r", options.user, (char *)NULL);
 655                 xfree(cp);
 656         }
 657         if (mux_command != 0 && options.control_path == NULL)
 658                 fatal("No ControlPath specified for \"-O\" command");
 659         if (options.control_path != NULL)
 660                 control_client(options.control_path);
 661
 662         /* Open a connection to the remote host. */
 663         if (ssh_connect(host, &hostaddr, options.port,
 664             options.address_family, options.connection_attempts,
 665 #ifdef HAVE_CYGWIN
 666             options.use_privileged_port,
 667 #else
 668             original_effective_uid == 0 && options.use_privileged_port,
 669 #endif
 670             options.proxy_command) != 0)
 671                 exit(1);
 672
 673         /*
 674          * If we successfully made the connection, load the host private key
 675          * in case we will need it later for combined rsa-rhosts
 676          * authentication. This must be done before releasing extra
 677          * privileges, because the file is only readable by root.
 678          * If we cannot access the private keys, load the public keys
 679          * instead and try to execute the ssh-keysign helper instead.
 680          */
 681         sensitive_data.nkeys = 0;
 682         sensitive_data.keys = NULL;
 683         sensitive_data.external_keysign = 0;
 684         if (options.rhosts_rsa_authentication ||
 685             options.hostbased_authentication) {
 686                 sensitive_data.nkeys = 3;
 687                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 688                     sizeof(Key));
 689
 690                 PRIV_START;
 691                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 692                     _PATH_HOST_KEY_FILE, "", NULL);
 693                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 694                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 695                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 696                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 697                 PRIV_END;
 698
 699                 if (options.hostbased_authentication == 1 &&
 700                     sensitive_data.keys[0] == NULL &&
 701                     sensitive_data.keys[1] == NULL &&
 702                     sensitive_data.keys[2] == NULL) {
 703                         sensitive_data.keys[1] = key_load_public(
 704                             _PATH_HOST_DSA_KEY_FILE, NULL);
 705                         sensitive_data.keys[2] = key_load_public(
 706                             _PATH_HOST_RSA_KEY_FILE, NULL);
 707                         sensitive_data.external_keysign = 1;
 708                 }
 709         }
 710         /*
 711          * Get rid of any extra privileges that we may have.  We will no
 712          * longer need them.  Also, extra privileges could make it very hard
 713          * to read identity files and other non-world-readable files from the
 714          * user's home directory if it happens to be on a NFS volume where
 715          * root is mapped to nobody.
 716          */
 717         if (original_effective_uid == 0) {
 718                 PRIV_START;
 719                 permanently_set_uid(pw);
 720         }
 721
 722         /*
 723          * Now that we are back to our own permissions, create ~/.ssh
 724          * directory if it doesn\'t already exist.
 725          */
 726         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 727         if (stat(buf, &st) < 0)
 728                 if (mkdir(buf, 0700) < 0)
 729                         error("Could not create directory '%.200s'.", buf);
 730
 731         /* load options.identity_files */
 732         load_public_identity_files();
 733
 734         /* Expand ~ in known host file names. */
 735         /* XXX mem-leaks: */
 736         options.system_hostfile =
 737             tilde_expand_filename(options.system_hostfile, original_real_uid);
 738         options.user_hostfile =
 739             tilde_expand_filename(options.user_hostfile, original_real_uid);
 740         options.system_hostfile2 =
 741             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 742         options.user_hostfile2 =
 743             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 744
 745         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 746
 747         /* Log into the remote system.  This never returns if the login fails. */
 748         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 749
 750         /* We no longer need the private host keys.  Clear them now. */
 751         if (sensitive_data.nkeys != 0) {
 752                 for (i = 0; i < sensitive_data.nkeys; i++) {
 753                         if (sensitive_data.keys[i] != NULL) {
 754                                 /* Destroys contents safely */
 755                                 debug3("clear hostkey %d", i);
 756                                 key_free(sensitive_data.keys[i]);
 757                                 sensitive_data.keys[i] = NULL;
 758                         }
 759                 }
 760                 xfree(sensitive_data.keys);
 761         }
 762         for (i = 0; i < options.num_identity_files; i++) {
 763                 if (options.identity_files[i]) {
 764                         xfree(options.identity_files[i]);
 765                         options.identity_files[i] = NULL;
 766                 }
 767                 if (options.identity_keys[i]) {
 768                         key_free(options.identity_keys[i]);
 769                         options.identity_keys[i] = NULL;
 770                 }
 771         }
 772
 773         exit_status = compat20 ? ssh_session2() : ssh_session();
 774         packet_close();
 775
 776         if (options.control_path != NULL && control_fd != -1)
 777                 unlink(options.control_path);
 778
 779         /*
 780          * Send SIGHUP to proxy command if used. We don't wait() in
 781          * case it hangs and instead rely on init to reap the child
 782          */
 783         if (proxy_command_pid > 1)
 784                 kill(proxy_command_pid, SIGHUP);
 785
 786         return exit_status;
 787 }
 788
 789 static void
 790 ssh_init_forwarding(void)
 791 {
 792         int success = 0;
 793         int i;
 794
 795         /* Initiate local TCP/IP port forwardings. */
 796         for (i = 0; i < options.num_local_forwards; i++) {
 797                 debug("Local connections to %.200s:%d forwarded to remote "
 798                     "address %.200s:%d",
 799                     (options.local_forwards[i].listen_host == NULL) ?
 800                     (options.gateway_ports ? "*" : "LOCALHOST") :
 801                     options.local_forwards[i].listen_host,
 802                     options.local_forwards[i].listen_port,
 803                     options.local_forwards[i].connect_host,
 804                     options.local_forwards[i].connect_port);
 805                 success += channel_setup_local_fwd_listener(
 806                     options.local_forwards[i].listen_host,
 807                     options.local_forwards[i].listen_port,
 808                     options.local_forwards[i].connect_host,
 809                     options.local_forwards[i].connect_port,
 810                     options.gateway_ports);
 811         }
 812         if (i > 0 && success == 0)
 813                 error("Could not request local forwarding.");
 814
 815         /* Initiate remote TCP/IP port forwardings. */
 816         for (i = 0; i < options.num_remote_forwards; i++) {
 817                 debug("Remote connections from %.200s:%d forwarded to "
 818                     "local address %.200s:%d",
 819                     (options.remote_forwards[i].listen_host == NULL) ?
 820                     (options.gateway_ports ? "*" : "LOCALHOST") :
 821                     options.remote_forwards[i].listen_host,
 822                     options.remote_forwards[i].listen_port,
 823                     options.remote_forwards[i].connect_host,
 824                     options.remote_forwards[i].connect_port);
 825                 channel_request_remote_forwarding(
 826                     options.remote_forwards[i].listen_host,
 827                     options.remote_forwards[i].listen_port,
 828                     options.remote_forwards[i].connect_host,
 829                     options.remote_forwards[i].connect_port);
 830         }
 831 }
 832
 833 static void
 834 check_agent_present(void)
 835 {
 836         if (options.forward_agent) {
 837                 /* Clear agent forwarding if we don\'t have an agent. */
 838                 if (!ssh_agent_present())
 839                         options.forward_agent = 0;
 840         }
 841 }
 842
 843 static int
 844 ssh_session(void)
 845 {
 846         int type;
 847         int interactive = 0;
 848         int have_tty = 0;
 849         struct winsize ws;
 850         char *cp;
 851         const char *display;
 852
 853         /* Enable compression if requested. */
 854         if (options.compression) {
 855                 debug("Requesting compression at level %d.", options.compression_level);
 856
 857                 if (options.compression_level < 1 || options.compression_level > 9)
 858                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 859
 860                 /* Send the request. */
 861                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 862                 packet_put_int(options.compression_level);
 863                 packet_send();
 864                 packet_write_wait();
 865                 type = packet_read();
 866                 if (type == SSH_SMSG_SUCCESS)
 867                         packet_start_compression(options.compression_level);
 868                 else if (type == SSH_SMSG_FAILURE)
 869                         logit("Warning: Remote host refused compression.");
 870                 else
 871                         packet_disconnect("Protocol error waiting for compression response.");
 872         }
 873         /* Allocate a pseudo tty if appropriate. */
 874         if (tty_flag) {
 875                 debug("Requesting pty.");
 876
 877                 /* Start the packet. */
 878                 packet_start(SSH_CMSG_REQUEST_PTY);
 879
 880                 /* Store TERM in the packet.  There is no limit on the
 881                    length of the string. */
 882                 cp = getenv("TERM");
 883                 if (!cp)
 884                         cp = "";
 885                 packet_put_cstring(cp);
 886
 887                 /* Store window size in the packet. */
 888                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 889                         memset(&ws, 0, sizeof(ws));
 890                 packet_put_int(ws.ws_row);
 891                 packet_put_int(ws.ws_col);
 892                 packet_put_int(ws.ws_xpixel);
 893                 packet_put_int(ws.ws_ypixel);
 894
 895                 /* Store tty modes in the packet. */
 896                 tty_make_modes(fileno(stdin), NULL);
 897
 898                 /* Send the packet, and wait for it to leave. */
 899                 packet_send();
 900                 packet_write_wait();
 901
 902                 /* Read response from the server. */
 903                 type = packet_read();
 904                 if (type == SSH_SMSG_SUCCESS) {
 905                         interactive = 1;
 906                         have_tty = 1;
 907                 } else if (type == SSH_SMSG_FAILURE)
 908                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 909                 else
 910                         packet_disconnect("Protocol error waiting for pty request response.");
 911         }
 912         /* Request X11 forwarding if enabled and DISPLAY is set. */
 913         display = getenv("DISPLAY");
 914         if (options.forward_x11 && display != NULL) {
 915                 char *proto, *data;
 916                 /* Get reasonable local authentication information. */
 917                 client_x11_get_proto(display, options.xauth_location,
 918                     options.forward_x11_trusted, &proto, &data);
 919                 /* Request forwarding with authentication spoofing. */
 920                 debug("Requesting X11 forwarding with authentication spoofing.");
 921                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 922
 923                 /* Read response from the server. */
 924                 type = packet_read();
 925                 if (type == SSH_SMSG_SUCCESS) {
 926                         interactive = 1;
 927                 } else if (type == SSH_SMSG_FAILURE) {
 928                         logit("Warning: Remote host denied X11 forwarding.");
 929                 } else {
 930                         packet_disconnect("Protocol error waiting for X11 forwarding");
 931                 }
 932         }
 933         /* Tell the packet module whether this is an interactive session. */
 934         packet_set_interactive(interactive);
 935
 936         /* Request authentication agent forwarding if appropriate. */
 937         check_agent_present();
 938
 939         if (options.forward_agent) {
 940                 debug("Requesting authentication agent forwarding.");
 941                 auth_request_forwarding();
 942
 943                 /* Read response from the server. */
 944                 type = packet_read();
 945                 packet_check_eom();
 946                 if (type != SSH_SMSG_SUCCESS)
 947                         logit("Warning: Remote host denied authentication agent forwarding.");
 948         }
 949
 950         /* Initiate port forwardings. */
 951         ssh_init_forwarding();
 952
 953         /* If requested, let ssh continue in the background. */
 954         if (fork_after_authentication_flag)
 955                 if (daemon(1, 1) < 0)
 956                         fatal("daemon() failed: %.200s", strerror(errno));
 957
 958         /*
 959          * If a command was specified on the command line, execute the
 960          * command now. Otherwise request the server to start a shell.
 961          */
 962         if (buffer_len(&command) > 0) {
 963                 int len = buffer_len(&command);
 964                 if (len > 900)
 965                         len = 900;
 966                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 967                 packet_start(SSH_CMSG_EXEC_CMD);
 968                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 969                 packet_send();
 970                 packet_write_wait();
 971         } else {
 972                 debug("Requesting shell.");
 973                 packet_start(SSH_CMSG_EXEC_SHELL);
 974                 packet_send();
 975                 packet_write_wait();
 976         }
 977
 978         /* Enter the interactive session. */
 979         return client_loop(have_tty, tty_flag ?
 980             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
 981 }
 982
 983 static void
 984 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
 985 {
 986         int id, len;
 987
 988         id = packet_get_int();
 989         len = buffer_len(&command);
 990         if (len > 900)
 991                 len = 900;
 992         packet_check_eom();
 993         if (type == SSH2_MSG_CHANNEL_FAILURE)
 994                 fatal("Request for subsystem '%.*s' failed on channel %d",
 995                     len, (u_char *)buffer_ptr(&command), id);
 996 }
 997
 998 void
 999 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1000 {
1001         int i;
1002
1003         i = client_global_request_id++;
1004         if (i >= options.num_remote_forwards)
1005                 return;
1006         debug("remote forward %s for: listen %d, connect %s:%d",
1007             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1008             options.remote_forwards[i].listen_port,
1009             options.remote_forwards[i].connect_host,
1010             options.remote_forwards[i].connect_port);
1011         if (type == SSH2_MSG_REQUEST_FAILURE)
1012                 logit("Warning: remote port forwarding failed for listen "
1013                     "port %d", options.remote_forwards[i].listen_port);
1014 }
1015
1016 static void
1017 ssh_control_listener(void)
1018 {
1019         struct sockaddr_un addr;
1020         mode_t old_umask;
1021         int addr_len;
1022
1023         if (options.control_path == NULL ||
1024             options.control_master == SSHCTL_MASTER_NO)
1025                 return;
1026
1027         debug("setting up multiplex master socket");
1028
1029         memset(&addr, '\0', sizeof(addr));
1030         addr.sun_family = AF_UNIX;
1031         addr_len = offsetof(struct sockaddr_un, sun_path) +
1032             strlen(options.control_path) + 1;
1033
1034         if (strlcpy(addr.sun_path, options.control_path,
1035             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1036                 fatal("ControlPath too long");
1037
1038         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1039                 fatal("%s socket(): %s\n", __func__, strerror(errno));
1040
1041         old_umask = umask(0177);
1042         if (bind(control_fd, (struct sockaddr*)&addr, addr_len) == -1) {
1043                 control_fd = -1;
1044                 if (errno == EINVAL || errno == EADDRINUSE)
1045                         fatal("ControlSocket %s already exists",
1046                             options.control_path);
1047                 else
1048                         fatal("%s bind(): %s\n", __func__, strerror(errno));
1049         }
1050         umask(old_umask);
1051
1052         if (listen(control_fd, 64) == -1)
1053                 fatal("%s listen(): %s\n", __func__, strerror(errno));
1054
1055         set_nonblock(control_fd);
1056 }
1057
1058 /* request pty/x11/agent/tcpfwd/shell for channel */
1059 static void
1060 ssh_session2_setup(int id, void *arg)
1061 {
1062         extern char **environ;
1063         const char *display;
1064         int interactive = tty_flag;
1065
1066         display = getenv("DISPLAY");
1067         if (options.forward_x11 && display != NULL) {
1068                 char *proto, *data;
1069                 /* Get reasonable local authentication information. */
1070                 client_x11_get_proto(display, options.xauth_location,
1071                     options.forward_x11_trusted, &proto, &data);
1072                 /* Request forwarding with authentication spoofing. */
1073                 debug("Requesting X11 forwarding with authentication spoofing.");
1074                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1075                 interactive = 1;
1076                 /* XXX wait for reply */
1077         }
1078
1079         check_agent_present();
1080         if (options.forward_agent) {
1081                 debug("Requesting authentication agent forwarding.");
1082                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1083                 packet_send();
1084         }
1085
1086         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1087             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1088
1089         packet_set_interactive(interactive);
1090 }
1091
1092 /* open new channel for a session */
1093 static int
1094 ssh_session2_open(void)
1095 {
1096         Channel *c;
1097         int window, packetmax, in, out, err;
1098
1099         if (stdin_null_flag) {
1100                 in = open(_PATH_DEVNULL, O_RDONLY);
1101         } else {
1102                 in = dup(STDIN_FILENO);
1103         }
1104         out = dup(STDOUT_FILENO);
1105         err = dup(STDERR_FILENO);
1106
1107         if (in < 0 || out < 0 || err < 0)
1108                 fatal("dup() in/out/err failed");
1109
1110         /* enable nonblocking unless tty */
1111         if (!isatty(in))
1112                 set_nonblock(in);
1113         if (!isatty(out))
1114                 set_nonblock(out);
1115         if (!isatty(err))
1116                 set_nonblock(err);
1117
1118         window = CHAN_SES_WINDOW_DEFAULT;
1119         packetmax = CHAN_SES_PACKET_DEFAULT;
1120         if (tty_flag) {
1121                 window >>= 1;
1122                 packetmax >>= 1;
1123         }
1124         c = channel_new(
1125             "session", SSH_CHANNEL_OPENING, in, out, err,
1126             window, packetmax, CHAN_EXTENDED_WRITE,
1127             "client-session", /*nonblock*/0);
1128
1129         debug3("ssh_session2_open: channel_new: %d", c->self);
1130
1131         channel_send_open(c->self);
1132         if (!no_shell_flag)
1133                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1134
1135         return c->self;
1136 }
1137
1138 static int
1139 ssh_session2(void)
1140 {
1141         int id = -1;
1142
1143         /* XXX should be pre-session */
1144         ssh_init_forwarding();
1145         ssh_control_listener();
1146
1147         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1148                 id = ssh_session2_open();
1149
1150         /* If requested, let ssh continue in the background. */
1151         if (fork_after_authentication_flag)
1152                 if (daemon(1, 1) < 0)
1153                         fatal("daemon() failed: %.200s", strerror(errno));
1154
1155         return client_loop(tty_flag, tty_flag ?
1156             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1157 }
1158
1159 static void
1160 load_public_identity_files(void)
1161 {
1162         char *filename;
1163         int i = 0;
1164         Key *public;
1165 #ifdef SMARTCARD
1166         Key **keys;
1167
1168         if (options.smartcard_device != NULL &&
1169             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1170             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1171                 int count = 0;
1172                 for (i = 0; keys[i] != NULL; i++) {
1173                         count++;
1174                         memmove(&options.identity_files[1], &options.identity_files[0],
1175                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1176                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1177                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1178                         options.num_identity_files++;
1179                         options.identity_keys[0] = keys[i];
1180                         options.identity_files[0] = sc_get_key_label(keys[i]);
1181                 }
1182                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1183                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1184                 i = count;
1185                 xfree(keys);
1186         }
1187 #endif /* SMARTCARD */
1188         for (; i < options.num_identity_files; i++) {
1189                 filename = tilde_expand_filename(options.identity_files[i],
1190                     original_real_uid);
1191                 public = key_load_public(filename, NULL);
1192                 debug("identity file %s type %d", filename,
1193                     public ? public->type : -1);
1194                 xfree(options.identity_files[i]);
1195                 options.identity_files[i] = filename;
1196                 options.identity_keys[i] = public;
1197         }
1198 }
1199
1200 static void
1201 control_client_sighandler(int signo)
1202 {
1203         control_client_terminate = signo;
1204 }
1205
1206 static void
1207 control_client_sigrelay(int signo)
1208 {
1209         if (control_server_pid > 1)
1210                 kill(control_server_pid, signo);
1211 }
1212
1213 static int
1214 env_permitted(char *env)
1215 {
1216         int i;
1217         char name[1024], *cp;
1218
1219         strlcpy(name, env, sizeof(name));
1220         if ((cp = strchr(name, '=')) == NULL)
1221                 return (0);
1222
1223         *cp = '\0';
1224
1225         for (i = 0; i < options.num_send_env; i++)
1226                 if (match_pattern(name, options.send_env[i]))
1227                         return (1);
1228
1229         return (0);
1230 }
1231
1232 static void
1233 control_client(const char *path)
1234 {
1235         struct sockaddr_un addr;
1236         int i, r, fd, sock, exitval, num_env, addr_len;
1237         Buffer m;
1238         char *term;
1239         extern char **environ;
1240         u_int  flags;
1241
1242         if (mux_command == 0)
1243                 mux_command = SSHMUX_COMMAND_OPEN;
1244
1245         switch (options.control_master) {
1246         case SSHCTL_MASTER_AUTO:
1247         case SSHCTL_MASTER_AUTO_ASK:
1248                 debug("auto-mux: Trying existing master");
1249                 /* FALLTHROUGH */
1250         case SSHCTL_MASTER_NO:
1251                 break;
1252         default:
1253                 return;
1254         }
1255
1256         memset(&addr, '\0', sizeof(addr));
1257         addr.sun_family = AF_UNIX;
1258         addr_len = offsetof(struct sockaddr_un, sun_path) +
1259             strlen(path) + 1;
1260
1261         if (strlcpy(addr.sun_path, path,
1262             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1263                 fatal("ControlPath too long");
1264
1265         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1266                 fatal("%s socket(): %s", __func__, strerror(errno));
1267
1268         if (connect(sock, (struct sockaddr*)&addr, addr_len) == -1) {
1269                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1270                         fatal("Control socket connect(%.100s): %s", path,
1271                             strerror(errno));
1272                 }
1273                 if (errno == ENOENT)
1274                         debug("Control socket \"%.100s\" does not exist", path);
1275                 else {
1276                         error("Control socket connect(%.100s): %s", path,
1277                             strerror(errno));
1278                 }
1279                 close(sock);
1280                 return;
1281         }
1282
1283         if (stdin_null_flag) {
1284                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1285                         fatal("open(/dev/null): %s", strerror(errno));
1286                 if (dup2(fd, STDIN_FILENO) == -1)
1287                         fatal("dup2: %s", strerror(errno));
1288                 if (fd > STDERR_FILENO)
1289                         close(fd);
1290         }
1291
1292         term = getenv("TERM");
1293
1294         flags = 0;
1295         if (tty_flag)
1296                 flags |= SSHMUX_FLAG_TTY;
1297         if (subsystem_flag)
1298                 flags |= SSHMUX_FLAG_SUBSYS;
1299         if (options.forward_x11)
1300                 flags |= SSHMUX_FLAG_X11_FWD;
1301         if (options.forward_agent)
1302                 flags |= SSHMUX_FLAG_AGENT_FWD;
1303
1304         buffer_init(&m);
1305
1306         /* Send our command to server */
1307         buffer_put_int(&m, mux_command);
1308         buffer_put_int(&m, flags);
1309         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1310                 fatal("%s: msg_send", __func__);
1311         buffer_clear(&m);
1312
1313         /* Get authorisation status and PID of controlee */
1314         if (ssh_msg_recv(sock, &m) == -1)
1315                 fatal("%s: msg_recv", __func__);
1316         if (buffer_get_char(&m) != SSHMUX_VER)
1317                 fatal("%s: wrong version", __func__);
1318         if (buffer_get_int(&m) != 1)
1319                 fatal("Connection to master denied");
1320         control_server_pid = buffer_get_int(&m);
1321
1322         buffer_clear(&m);
1323
1324         switch (mux_command) {
1325         case SSHMUX_COMMAND_ALIVE_CHECK:
1326                 fprintf(stderr, "Master running (pid=%d)\r\n",
1327                     control_server_pid);
1328                 exit(0);
1329         case SSHMUX_COMMAND_TERMINATE:
1330                 fprintf(stderr, "Exit request sent.\r\n");
1331                 exit(0);
1332         case SSHMUX_COMMAND_OPEN:
1333                 /* continue below */
1334                 break;
1335         default:
1336                 fatal("silly mux_command %d", mux_command);
1337         }
1338
1339         /* SSHMUX_COMMAND_OPEN */
1340         buffer_put_cstring(&m, term ? term : "");
1341         buffer_append(&command, "\0", 1);
1342         buffer_put_cstring(&m, buffer_ptr(&command));
1343
1344         if (options.num_send_env == 0 || environ == NULL) {
1345                 buffer_put_int(&m, 0);
1346         } else {
1347                 /* Pass environment */
1348                 num_env = 0;
1349                 for (i = 0; environ[i] != NULL; i++)
1350                         if (env_permitted(environ[i]))
1351                                 num_env++; /* Count */
1352
1353                 buffer_put_int(&m, num_env);
1354
1355                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1356                         if (env_permitted(environ[i])) {
1357                                 num_env--;
1358                                 buffer_put_cstring(&m, environ[i]);
1359                         }
1360         }
1361
1362         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1363                 fatal("%s: msg_send", __func__);
1364
1365         mm_send_fd(sock, STDIN_FILENO);
1366         mm_send_fd(sock, STDOUT_FILENO);
1367         mm_send_fd(sock, STDERR_FILENO);
1368
1369         /* Wait for reply, so master has a chance to gather ttymodes */
1370         buffer_clear(&m);
1371         if (ssh_msg_recv(sock, &m) == -1)
1372                 fatal("%s: msg_recv", __func__);
1373         if (buffer_get_char(&m) != SSHMUX_VER)
1374                 fatal("%s: wrong version", __func__);
1375         buffer_free(&m);
1376
1377         signal(SIGHUP, control_client_sighandler);
1378         signal(SIGINT, control_client_sighandler);
1379         signal(SIGTERM, control_client_sighandler);
1380         signal(SIGWINCH, control_client_sigrelay);
1381
1382         if (tty_flag)
1383                 enter_raw_mode();
1384
1385         /* Stick around until the controlee closes the client_fd */
1386         exitval = 0;
1387         for (;!control_client_terminate;) {
1388                 r = read(sock, &exitval, sizeof(exitval));
1389                 if (r == 0) {
1390                         debug2("Received EOF from master");
1391                         break;
1392                 }
1393                 if (r > 0)
1394                         debug2("Received exit status from master %d", exitval);
1395                 if (r == -1 && errno != EINTR)
1396                         fatal("%s: read %s", __func__, strerror(errno));
1397         }
1398
1399         if (control_client_terminate)
1400                 debug2("Exiting on signal %d", control_client_terminate);
1401
1402         close(sock);
1403
1404         leave_raw_mode();
1405
1406         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1407                 fprintf(stderr, "Connection to master closed.\r\n");
1408
1409         exit(exitval);
1410 }