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 1.229 2004/11/07 00:01:46 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 = SSHMUX_COMMAND_OPEN;
 149
 150 /* Only used in control client mode */
 151 volatile sig_atomic_t control_client_terminate = 0;
 152 u_int control_server_pid = 0;
 153
 154 /* Prints a help message to the user.  This function never returns. */
 155
 156 static void
 157 usage(void)
 158 {
 159         fprintf(stderr,
 160 "usage: ssh [-1246AaCfghkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 161 "           [-D port] [-e escape_char] [-F configfile] [-i identity_file]\n"
 162 "           [-L port:host:hostport] [-l login_name] [-m mac_spec] [-o option]\n"
 163 "           [-p port] [-R port:host:hostport] [-S ctl] [user@]hostname [command]\n"
 164         );
 165         exit(1);
 166 }
 167
 168 static int ssh_session(void);
 169 static int ssh_session2(void);
 170 static void load_public_identity_files(void);
 171 static void control_client(const char *path);
 172
 173 /*
 174  * Main program for the ssh client.
 175  */
 176 int
 177 main(int ac, char **av)
 178 {
 179         int i, opt, exit_status;
 180         u_short fwd_port, fwd_host_port;
 181         char sfwd_port[6], sfwd_host_port[6];
 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
 189         __progname = ssh_get_progname(av[0]);
 190         init_rng();
 191
 192         /*
 193          * Save the original real uid.  It will be needed later (uid-swapping
 194          * may clobber the real uid).
 195          */
 196         original_real_uid = getuid();
 197         original_effective_uid = geteuid();
 198
 199         /*
 200          * Use uid-swapping to give up root privileges for the duration of
 201          * option processing.  We will re-instantiate the rights when we are
 202          * ready to create the privileged port, and will permanently drop
 203          * them when the port has been created (actually, when the connection
 204          * has been made, as we may need to create the port several times).
 205          */
 206         PRIV_END;
 207
 208 #ifdef HAVE_SETRLIMIT
 209         /* If we are installed setuid root be careful to not drop core. */
 210         if (original_real_uid != original_effective_uid) {
 211                 struct rlimit rlim;
 212                 rlim.rlim_cur = rlim.rlim_max = 0;
 213                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 214                         fatal("setrlimit failed: %.100s", strerror(errno));
 215         }
 216 #endif
 217         /* Get user data. */
 218         pw = getpwuid(original_real_uid);
 219         if (!pw) {
 220                 logit("You don't exist, go away!");
 221                 exit(1);
 222         }
 223         /* Take a copy of the returned structure. */
 224         pw = pwcopy(pw);
 225
 226         /*
 227          * Set our umask to something reasonable, as some files are created
 228          * with the default umask.  This will make them world-readable but
 229          * writable only by the owner, which is ok for all files for which we
 230          * don't set the modes explicitly.
 231          */
 232         umask(022);
 233
 234         /* Initialize option structure to indicate that no values have been set. */
 235         initialize_options(&options);
 236
 237         /* Parse command-line arguments. */
 238         host = NULL;
 239
 240 again:
 241         while ((opt = getopt(ac, av,
 242             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:MNO:PR:S:TVXY")) != -1) {
 243                 switch (opt) {
 244                 case '1':
 245                         options.protocol = SSH_PROTO_1;
 246                         break;
 247                 case '2':
 248                         options.protocol = SSH_PROTO_2;
 249                         break;
 250                 case '4':
 251                         options.address_family = AF_INET;
 252                         break;
 253                 case '6':
 254                         options.address_family = AF_INET6;
 255                         break;
 256                 case 'n':
 257                         stdin_null_flag = 1;
 258                         break;
 259                 case 'f':
 260                         fork_after_authentication_flag = 1;
 261                         stdin_null_flag = 1;
 262                         break;
 263                 case 'x':
 264                         options.forward_x11 = 0;
 265                         break;
 266                 case 'X':
 267                         options.forward_x11 = 1;
 268                         break;
 269                 case 'Y':
 270                         options.forward_x11 = 1;
 271                         options.forward_x11_trusted = 1;
 272                         break;
 273                 case 'g':
 274                         options.gateway_ports = 1;
 275                         break;
 276                 case 'O':
 277                         if (strcmp(optarg, "check") == 0)
 278                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 279                         else if (strcmp(optarg, "exit") == 0)
 280                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 281                         else
 282                                 fatal("Invalid multiplex command.");
 283                         break;
 284                 case 'P':       /* deprecated */
 285                         options.use_privileged_port = 0;
 286                         break;
 287                 case 'a':
 288                         options.forward_agent = 0;
 289                         break;
 290                 case 'A':
 291                         options.forward_agent = 1;
 292                         break;
 293                 case 'k':
 294                         options.gss_deleg_creds = 0;
 295                         break;
 296                 case 'i':
 297                         if (stat(optarg, &st) < 0) {
 298                                 fprintf(stderr, "Warning: Identity file %s "
 299                                     "does not exist.\n", optarg);
 300                                 break;
 301                         }
 302                         if (options.num_identity_files >=
 303                             SSH_MAX_IDENTITY_FILES)
 304                                 fatal("Too many identity files specified "
 305                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 306                         options.identity_files[options.num_identity_files++] =
 307                             xstrdup(optarg);
 308                         break;
 309                 case 'I':
 310 #ifdef SMARTCARD
 311                         options.smartcard_device = xstrdup(optarg);
 312 #else
 313                         fprintf(stderr, "no support for smartcards.\n");
 314 #endif
 315                         break;
 316                 case 't':
 317                         if (tty_flag)
 318                                 force_tty_flag = 1;
 319                         tty_flag = 1;
 320                         break;
 321                 case 'v':
 322                         if (debug_flag == 0) {
 323                                 debug_flag = 1;
 324                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 325                         } else {
 326                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 327                                         options.log_level++;
 328                                 break;
 329                         }
 330                         /* FALLTHROUGH */
 331                 case 'V':
 332                         fprintf(stderr, "%s, %s\n",
 333                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 334                         if (opt == 'V')
 335                                 exit(0);
 336                         break;
 337                 case 'q':
 338                         options.log_level = SYSLOG_LEVEL_QUIET;
 339                         break;
 340                 case 'e':
 341                         if (optarg[0] == '^' && optarg[2] == 0 &&
 342                             (u_char) optarg[1] >= 64 &&
 343                             (u_char) optarg[1] < 128)
 344                                 options.escape_char = (u_char) optarg[1] & 31;
 345                         else if (strlen(optarg) == 1)
 346                                 options.escape_char = (u_char) optarg[0];
 347                         else if (strcmp(optarg, "none") == 0)
 348                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 349                         else {
 350                                 fprintf(stderr, "Bad escape character '%s'.\n",
 351                                     optarg);
 352                                 exit(1);
 353                         }
 354                         break;
 355                 case 'c':
 356                         if (ciphers_valid(optarg)) {
 357                                 /* SSH2 only */
 358                                 options.ciphers = xstrdup(optarg);
 359                                 options.cipher = SSH_CIPHER_INVALID;
 360                         } else {
 361                                 /* SSH1 only */
 362                                 options.cipher = cipher_number(optarg);
 363                                 if (options.cipher == -1) {
 364                                         fprintf(stderr,
 365                                             "Unknown cipher type '%s'\n",
 366                                             optarg);
 367                                         exit(1);
 368                                 }
 369                                 if (options.cipher == SSH_CIPHER_3DES)
 370                                         options.ciphers = "3des-cbc";
 371                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 372                                         options.ciphers = "blowfish-cbc";
 373                                 else
 374                                         options.ciphers = (char *)-1;
 375                         }
 376                         break;
 377                 case 'm':
 378                         if (mac_valid(optarg))
 379                                 options.macs = xstrdup(optarg);
 380                         else {
 381                                 fprintf(stderr, "Unknown mac type '%s'\n",
 382                                     optarg);
 383                                 exit(1);
 384                         }
 385                         break;
 386                 case 'M':
 387                         options.control_master =
 388                             (options.control_master >= 1) ? 2 : 1;
 389                         break;
 390                 case 'p':
 391                         options.port = a2port(optarg);
 392                         if (options.port == 0) {
 393                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 394                                 exit(1);
 395                         }
 396                         break;
 397                 case 'l':
 398                         options.user = optarg;
 399                         break;
 400
 401                 case 'L':
 402                 case 'R':
 403                         if (sscanf(optarg, "%5[0123456789]:%255[^:]:%5[0123456789]",
 404                             sfwd_port, buf, sfwd_host_port) != 3 &&
 405                             sscanf(optarg, "%5[0123456789]/%255[^/]/%5[0123456789]",
 406                             sfwd_port, buf, sfwd_host_port) != 3) {
 407                                 fprintf(stderr,
 408                                     "Bad forwarding specification '%s'\n",
 409                                     optarg);
 410                                 usage();
 411                                 /* NOTREACHED */
 412                         }
 413                         if ((fwd_port = a2port(sfwd_port)) == 0 ||
 414                             (fwd_host_port = a2port(sfwd_host_port)) == 0) {
 415                                 fprintf(stderr,
 416                                     "Bad forwarding port(s) '%s'\n", optarg);
 417                                 exit(1);
 418                         }
 419                         if (opt == 'L')
 420                                 add_local_forward(&options, fwd_port, buf,
 421                                     fwd_host_port);
 422                         else if (opt == 'R')
 423                                 add_remote_forward(&options, fwd_port, buf,
 424                                     fwd_host_port);
 425                         break;
 426
 427                 case 'D':
 428                         fwd_port = a2port(optarg);
 429                         if (fwd_port == 0) {
 430                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 431                                     optarg);
 432                                 exit(1);
 433                         }
 434                         add_local_forward(&options, fwd_port, "socks", 0);
 435                         break;
 436
 437                 case 'C':
 438                         options.compression = 1;
 439                         break;
 440                 case 'N':
 441                         no_shell_flag = 1;
 442                         no_tty_flag = 1;
 443                         break;
 444                 case 'T':
 445                         no_tty_flag = 1;
 446                         break;
 447                 case 'o':
 448                         dummy = 1;
 449                         line = xstrdup(optarg);
 450                         if (process_config_line(&options, host ? host : "",
 451                             line, "command-line", 0, &dummy) != 0)
 452                                 exit(1);
 453                         xfree(line);
 454                         break;
 455                 case 's':
 456                         subsystem_flag = 1;
 457                         break;
 458                 case 'S':
 459                         if (options.control_path != NULL)
 460                                 free(options.control_path);
 461                         options.control_path = xstrdup(optarg);
 462                         break;
 463                 case 'b':
 464                         options.bind_address = optarg;
 465                         break;
 466                 case 'F':
 467                         config = optarg;
 468                         break;
 469                 default:
 470                         usage();
 471                 }
 472         }
 473
 474         ac -= optind;
 475         av += optind;
 476
 477         if (ac > 0 && !host && **av != '-') {
 478                 if (strrchr(*av, '@')) {
 479                         p = xstrdup(*av);
 480                         cp = strrchr(p, '@');
 481                         if (cp == NULL || cp == p)
 482                                 usage();
 483                         options.user = p;
 484                         *cp = '\0';
 485                         host = ++cp;
 486                 } else
 487                         host = *av;
 488                 if (ac > 1) {
 489                         optind = optreset = 1;
 490                         goto again;
 491                 }
 492                 ac--, av++;
 493         }
 494
 495         /* Check that we got a host name. */
 496         if (!host)
 497                 usage();
 498
 499         SSLeay_add_all_algorithms();
 500         ERR_load_crypto_strings();
 501
 502         /* Initialize the command to execute on remote host. */
 503         buffer_init(&command);
 504
 505         /*
 506          * Save the command to execute on the remote host in a buffer. There
 507          * is no limit on the length of the command, except by the maximum
 508          * packet size.  Also sets the tty flag if there is no command.
 509          */
 510         if (!ac) {
 511                 /* No command specified - execute shell on a tty. */
 512                 tty_flag = 1;
 513                 if (subsystem_flag) {
 514                         fprintf(stderr,
 515                             "You must specify a subsystem to invoke.\n");
 516                         usage();
 517                 }
 518         } else {
 519                 /* A command has been specified.  Store it into the buffer. */
 520                 for (i = 0; i < ac; i++) {
 521                         if (i)
 522                                 buffer_append(&command, " ", 1);
 523                         buffer_append(&command, av[i], strlen(av[i]));
 524                 }
 525         }
 526
 527         /* Cannot fork to background if no command. */
 528         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 529                 fatal("Cannot fork into background without a command to execute.");
 530
 531         /* Allocate a tty by default if no command specified. */
 532         if (buffer_len(&command) == 0)
 533                 tty_flag = 1;
 534
 535         /* Force no tty */
 536         if (no_tty_flag)
 537                 tty_flag = 0;
 538         /* Do not allocate a tty if stdin is not a tty. */
 539         if (!isatty(fileno(stdin)) && !force_tty_flag) {
 540                 if (tty_flag)
 541                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 542                 tty_flag = 0;
 543         }
 544
 545         /*
 546          * Initialize "log" output.  Since we are the client all output
 547          * actually goes to stderr.
 548          */
 549         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 550             SYSLOG_FACILITY_USER, 1);
 551
 552         /*
 553          * Read per-user configuration file.  Ignore the system wide config
 554          * file if the user specifies a config file on the command line.
 555          */
 556         if (config != NULL) {
 557                 if (!read_config_file(config, host, &options, 0))
 558                         fatal("Can't open user config file %.100s: "
 559                             "%.100s", config, strerror(errno));
 560         } else  {
 561                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 562                     _PATH_SSH_USER_CONFFILE);
 563                 (void)read_config_file(buf, host, &options, 1);
 564
 565                 /* Read systemwide configuration file after use config. */
 566                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 567                     &options, 0);
 568         }
 569
 570         /* Fill configuration defaults. */
 571         fill_default_options(&options);
 572
 573         channel_set_af(options.address_family);
 574
 575         /* reinit */
 576         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 577
 578         seed_rng();
 579
 580         if (options.user == NULL)
 581                 options.user = xstrdup(pw->pw_name);
 582
 583         if (options.hostname != NULL)
 584                 host = options.hostname;
 585
 586         /* force lowercase for hostkey matching */
 587         if (options.host_key_alias != NULL) {
 588                 for (p = options.host_key_alias; *p; p++)
 589                         if (isupper(*p))
 590                                 *p = tolower(*p);
 591         }
 592
 593         if (options.proxy_command != NULL &&
 594             strcmp(options.proxy_command, "none") == 0)
 595                 options.proxy_command = NULL;
 596
 597         if (options.control_path != NULL) {
 598                 options.control_path = tilde_expand_filename(
 599                    options.control_path, original_real_uid);
 600         }
 601         if (options.control_path != NULL && options.control_master == 0)
 602                 control_client(options.control_path); /* This doesn't return */
 603
 604         /* Open a connection to the remote host. */
 605         if (ssh_connect(host, &hostaddr, options.port,
 606             options.address_family, options.connection_attempts,
 607 #ifdef HAVE_CYGWIN
 608             options.use_privileged_port,
 609 #else
 610             original_effective_uid == 0 && options.use_privileged_port,
 611 #endif
 612             options.proxy_command) != 0)
 613                 exit(1);
 614
 615         /*
 616          * If we successfully made the connection, load the host private key
 617          * in case we will need it later for combined rsa-rhosts
 618          * authentication. This must be done before releasing extra
 619          * privileges, because the file is only readable by root.
 620          * If we cannot access the private keys, load the public keys
 621          * instead and try to execute the ssh-keysign helper instead.
 622          */
 623         sensitive_data.nkeys = 0;
 624         sensitive_data.keys = NULL;
 625         sensitive_data.external_keysign = 0;
 626         if (options.rhosts_rsa_authentication ||
 627             options.hostbased_authentication) {
 628                 sensitive_data.nkeys = 3;
 629                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 630                     sizeof(Key));
 631
 632                 PRIV_START;
 633                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 634                     _PATH_HOST_KEY_FILE, "", NULL);
 635                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 636                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 637                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 638                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 639                 PRIV_END;
 640
 641                 if (options.hostbased_authentication == 1 &&
 642                     sensitive_data.keys[0] == NULL &&
 643                     sensitive_data.keys[1] == NULL &&
 644                     sensitive_data.keys[2] == NULL) {
 645                         sensitive_data.keys[1] = key_load_public(
 646                             _PATH_HOST_DSA_KEY_FILE, NULL);
 647                         sensitive_data.keys[2] = key_load_public(
 648                             _PATH_HOST_RSA_KEY_FILE, NULL);
 649                         sensitive_data.external_keysign = 1;
 650                 }
 651         }
 652         /*
 653          * Get rid of any extra privileges that we may have.  We will no
 654          * longer need them.  Also, extra privileges could make it very hard
 655          * to read identity files and other non-world-readable files from the
 656          * user's home directory if it happens to be on a NFS volume where
 657          * root is mapped to nobody.
 658          */
 659         if (original_effective_uid == 0) {
 660                 PRIV_START;
 661                 permanently_set_uid(pw);
 662         }
 663
 664         /*
 665          * Now that we are back to our own permissions, create ~/.ssh
 666          * directory if it doesn\'t already exist.
 667          */
 668         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 669         if (stat(buf, &st) < 0)
 670                 if (mkdir(buf, 0700) < 0)
 671                         error("Could not create directory '%.200s'.", buf);
 672
 673         /* load options.identity_files */
 674         load_public_identity_files();
 675
 676         /* Expand ~ in known host file names. */
 677         /* XXX mem-leaks: */
 678         options.system_hostfile =
 679             tilde_expand_filename(options.system_hostfile, original_real_uid);
 680         options.user_hostfile =
 681             tilde_expand_filename(options.user_hostfile, original_real_uid);
 682         options.system_hostfile2 =
 683             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 684         options.user_hostfile2 =
 685             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 686
 687         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 688
 689         /* Log into the remote system.  This never returns if the login fails. */
 690         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 691
 692         /* We no longer need the private host keys.  Clear them now. */
 693         if (sensitive_data.nkeys != 0) {
 694                 for (i = 0; i < sensitive_data.nkeys; i++) {
 695                         if (sensitive_data.keys[i] != NULL) {
 696                                 /* Destroys contents safely */
 697                                 debug3("clear hostkey %d", i);
 698                                 key_free(sensitive_data.keys[i]);
 699                                 sensitive_data.keys[i] = NULL;
 700                         }
 701                 }
 702                 xfree(sensitive_data.keys);
 703         }
 704         for (i = 0; i < options.num_identity_files; i++) {
 705                 if (options.identity_files[i]) {
 706                         xfree(options.identity_files[i]);
 707                         options.identity_files[i] = NULL;
 708                 }
 709                 if (options.identity_keys[i]) {
 710                         key_free(options.identity_keys[i]);
 711                         options.identity_keys[i] = NULL;
 712                 }
 713         }
 714
 715         exit_status = compat20 ? ssh_session2() : ssh_session();
 716         packet_close();
 717
 718         if (options.control_path != NULL && control_fd != -1)
 719                 unlink(options.control_path);
 720
 721         /*
 722          * Send SIGHUP to proxy command if used. We don't wait() in
 723          * case it hangs and instead rely on init to reap the child
 724          */
 725         if (proxy_command_pid > 1)
 726                 kill(proxy_command_pid, SIGHUP);
 727
 728         return exit_status;
 729 }
 730
 731 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
 732
 733 static void
 734 x11_get_proto(char **_proto, char **_data)
 735 {
 736         char cmd[1024];
 737         char line[512];
 738         char xdisplay[512];
 739         static char proto[512], data[512];
 740         FILE *f;
 741         int got_data = 0, generated = 0, do_unlink = 0, i;
 742         char *display, *xauthdir, *xauthfile;
 743         struct stat st;
 744
 745         xauthdir = xauthfile = NULL;
 746         *_proto = proto;
 747         *_data = data;
 748         proto[0] = data[0] = '\0';
 749
 750         if (!options.xauth_location ||
 751             (stat(options.xauth_location, &st) == -1)) {
 752                 debug("No xauth program.");
 753         } else {
 754                 if ((display = getenv("DISPLAY")) == NULL) {
 755                         debug("x11_get_proto: DISPLAY not set");
 756                         return;
 757                 }
 758                 /*
 759                  * Handle FamilyLocal case where $DISPLAY does
 760                  * not match an authorization entry.  For this we
 761                  * just try "xauth list unix:displaynum.screennum".
 762                  * XXX: "localhost" match to determine FamilyLocal
 763                  *      is not perfect.
 764                  */
 765                 if (strncmp(display, "localhost:", 10) == 0) {
 766                         snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
 767                             display + 10);
 768                         display = xdisplay;
 769                 }
 770                 if (options.forward_x11_trusted == 0) {
 771                         xauthdir = xmalloc(MAXPATHLEN);
 772                         xauthfile = xmalloc(MAXPATHLEN);
 773                         strlcpy(xauthdir, "/tmp/ssh-XXXXXXXXXX", MAXPATHLEN);
 774                         if (mkdtemp(xauthdir) != NULL) {
 775                                 do_unlink = 1;
 776                                 snprintf(xauthfile, MAXPATHLEN, "%s/xauthfile",
 777                                     xauthdir);
 778                                 snprintf(cmd, sizeof(cmd),
 779                                     "%s -f %s generate %s " SSH_X11_PROTO
 780                                     " untrusted timeout 1200 2>" _PATH_DEVNULL,
 781                                     options.xauth_location, xauthfile, display);
 782                                 debug2("x11_get_proto: %s", cmd);
 783                                 if (system(cmd) == 0)
 784                                         generated = 1;
 785                         }
 786                 }
 787                 snprintf(cmd, sizeof(cmd),
 788                     "%s %s%s list %s . 2>" _PATH_DEVNULL,
 789                     options.xauth_location,
 790                     generated ? "-f " : "" ,
 791                     generated ? xauthfile : "",
 792                     display);
 793                 debug2("x11_get_proto: %s", cmd);
 794                 f = popen(cmd, "r");
 795                 if (f && fgets(line, sizeof(line), f) &&
 796                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 797                         got_data = 1;
 798                 if (f)
 799                         pclose(f);
 800         }
 801
 802         if (do_unlink) {
 803                 unlink(xauthfile);
 804                 rmdir(xauthdir);
 805         }
 806         if (xauthdir)
 807                 xfree(xauthdir);
 808         if (xauthfile)
 809                 xfree(xauthfile);
 810
 811         /*
 812          * If we didn't get authentication data, just make up some
 813          * data.  The forwarding code will check the validity of the
 814          * response anyway, and substitute this data.  The X11
 815          * server, however, will ignore this fake data and use
 816          * whatever authentication mechanisms it was using otherwise
 817          * for the local connection.
 818          */
 819         if (!got_data) {
 820                 u_int32_t rnd = 0;
 821
 822                 logit("Warning: No xauth data; "
 823                     "using fake authentication data for X11 forwarding.");
 824                 strlcpy(proto, SSH_X11_PROTO, sizeof proto);
 825                 for (i = 0; i < 16; i++) {
 826                         if (i % 4 == 0)
 827                                 rnd = arc4random();
 828                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
 829                             rnd & 0xff);
 830                         rnd >>= 8;
 831                 }
 832         }
 833 }
 834
 835 static void
 836 ssh_init_forwarding(void)
 837 {
 838         int success = 0;
 839         int i;
 840
 841         /* Initiate local TCP/IP port forwardings. */
 842         for (i = 0; i < options.num_local_forwards; i++) {
 843                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
 844                     options.local_forwards[i].port,
 845                     options.local_forwards[i].host,
 846                     options.local_forwards[i].host_port);
 847                 success += channel_setup_local_fwd_listener(
 848                     options.local_forwards[i].port,
 849                     options.local_forwards[i].host,
 850                     options.local_forwards[i].host_port,
 851                     options.gateway_ports);
 852         }
 853         if (i > 0 && success == 0)
 854                 error("Could not request local forwarding.");
 855
 856         /* Initiate remote TCP/IP port forwardings. */
 857         for (i = 0; i < options.num_remote_forwards; i++) {
 858                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
 859                     options.remote_forwards[i].port,
 860                     options.remote_forwards[i].host,
 861                     options.remote_forwards[i].host_port);
 862                 channel_request_remote_forwarding(
 863                     options.remote_forwards[i].port,
 864                     options.remote_forwards[i].host,
 865                     options.remote_forwards[i].host_port);
 866         }
 867 }
 868
 869 static void
 870 check_agent_present(void)
 871 {
 872         if (options.forward_agent) {
 873                 /* Clear agent forwarding if we don\'t have an agent. */
 874                 if (!ssh_agent_present())
 875                         options.forward_agent = 0;
 876         }
 877 }
 878
 879 static int
 880 ssh_session(void)
 881 {
 882         int type;
 883         int interactive = 0;
 884         int have_tty = 0;
 885         struct winsize ws;
 886         char *cp;
 887
 888         /* Enable compression if requested. */
 889         if (options.compression) {
 890                 debug("Requesting compression at level %d.", options.compression_level);
 891
 892                 if (options.compression_level < 1 || options.compression_level > 9)
 893                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 894
 895                 /* Send the request. */
 896                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 897                 packet_put_int(options.compression_level);
 898                 packet_send();
 899                 packet_write_wait();
 900                 type = packet_read();
 901                 if (type == SSH_SMSG_SUCCESS)
 902                         packet_start_compression(options.compression_level);
 903                 else if (type == SSH_SMSG_FAILURE)
 904                         logit("Warning: Remote host refused compression.");
 905                 else
 906                         packet_disconnect("Protocol error waiting for compression response.");
 907         }
 908         /* Allocate a pseudo tty if appropriate. */
 909         if (tty_flag) {
 910                 debug("Requesting pty.");
 911
 912                 /* Start the packet. */
 913                 packet_start(SSH_CMSG_REQUEST_PTY);
 914
 915                 /* Store TERM in the packet.  There is no limit on the
 916                    length of the string. */
 917                 cp = getenv("TERM");
 918                 if (!cp)
 919                         cp = "";
 920                 packet_put_cstring(cp);
 921
 922                 /* Store window size in the packet. */
 923                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 924                         memset(&ws, 0, sizeof(ws));
 925                 packet_put_int(ws.ws_row);
 926                 packet_put_int(ws.ws_col);
 927                 packet_put_int(ws.ws_xpixel);
 928                 packet_put_int(ws.ws_ypixel);
 929
 930                 /* Store tty modes in the packet. */
 931                 tty_make_modes(fileno(stdin), NULL);
 932
 933                 /* Send the packet, and wait for it to leave. */
 934                 packet_send();
 935                 packet_write_wait();
 936
 937                 /* Read response from the server. */
 938                 type = packet_read();
 939                 if (type == SSH_SMSG_SUCCESS) {
 940                         interactive = 1;
 941                         have_tty = 1;
 942                 } else if (type == SSH_SMSG_FAILURE)
 943                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 944                 else
 945                         packet_disconnect("Protocol error waiting for pty request response.");
 946         }
 947         /* Request X11 forwarding if enabled and DISPLAY is set. */
 948         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 949                 char *proto, *data;
 950                 /* Get reasonable local authentication information. */
 951                 x11_get_proto(&proto, &data);
 952                 /* Request forwarding with authentication spoofing. */
 953                 debug("Requesting X11 forwarding with authentication spoofing.");
 954                 x11_request_forwarding_with_spoofing(0, proto, data);
 955
 956                 /* Read response from the server. */
 957                 type = packet_read();
 958                 if (type == SSH_SMSG_SUCCESS) {
 959                         interactive = 1;
 960                 } else if (type == SSH_SMSG_FAILURE) {
 961                         logit("Warning: Remote host denied X11 forwarding.");
 962                 } else {
 963                         packet_disconnect("Protocol error waiting for X11 forwarding");
 964                 }
 965         }
 966         /* Tell the packet module whether this is an interactive session. */
 967         packet_set_interactive(interactive);
 968
 969         /* Request authentication agent forwarding if appropriate. */
 970         check_agent_present();
 971
 972         if (options.forward_agent) {
 973                 debug("Requesting authentication agent forwarding.");
 974                 auth_request_forwarding();
 975
 976                 /* Read response from the server. */
 977                 type = packet_read();
 978                 packet_check_eom();
 979                 if (type != SSH_SMSG_SUCCESS)
 980                         logit("Warning: Remote host denied authentication agent forwarding.");
 981         }
 982
 983         /* Initiate port forwardings. */
 984         ssh_init_forwarding();
 985
 986         /* If requested, let ssh continue in the background. */
 987         if (fork_after_authentication_flag)
 988                 if (daemon(1, 1) < 0)
 989                         fatal("daemon() failed: %.200s", strerror(errno));
 990
 991         /*
 992          * If a command was specified on the command line, execute the
 993          * command now. Otherwise request the server to start a shell.
 994          */
 995         if (buffer_len(&command) > 0) {
 996                 int len = buffer_len(&command);
 997                 if (len > 900)
 998                         len = 900;
 999                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1000                 packet_start(SSH_CMSG_EXEC_CMD);
1001                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1002                 packet_send();
1003                 packet_write_wait();
1004         } else {
1005                 debug("Requesting shell.");
1006                 packet_start(SSH_CMSG_EXEC_SHELL);
1007                 packet_send();
1008                 packet_write_wait();
1009         }
1010
1011         /* Enter the interactive session. */
1012         return client_loop(have_tty, tty_flag ?
1013             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1014 }
1015
1016 static void
1017 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1018 {
1019         int id, len;
1020
1021         id = packet_get_int();
1022         len = buffer_len(&command);
1023         if (len > 900)
1024                 len = 900;
1025         packet_check_eom();
1026         if (type == SSH2_MSG_CHANNEL_FAILURE)
1027                 fatal("Request for subsystem '%.*s' failed on channel %d",
1028                     len, (u_char *)buffer_ptr(&command), id);
1029 }
1030
1031 void
1032 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1033 {
1034         int i;
1035
1036         i = client_global_request_id++;
1037         if (i >= options.num_remote_forwards)
1038                 return;
1039         debug("remote forward %s for: listen %d, connect %s:%d",
1040             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1041             options.remote_forwards[i].port,
1042             options.remote_forwards[i].host,
1043             options.remote_forwards[i].host_port);
1044         if (type == SSH2_MSG_REQUEST_FAILURE)
1045                 logit("Warning: remote port forwarding failed for listen port %d",
1046                     options.remote_forwards[i].port);
1047 }
1048
1049 static void
1050 ssh_control_listener(void)
1051 {
1052         struct sockaddr_un addr;
1053         mode_t old_umask;
1054         int addr_len;
1055
1056         if (options.control_path == NULL || options.control_master <= 0)
1057                 return;
1058
1059         memset(&addr, '\0', sizeof(addr));
1060         addr.sun_family = AF_UNIX;
1061         addr_len = offsetof(struct sockaddr_un, sun_path) +
1062             strlen(options.control_path) + 1;
1063
1064         if (strlcpy(addr.sun_path, options.control_path,
1065             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1066                 fatal("ControlPath too long");
1067
1068         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1069                 fatal("%s socket(): %s\n", __func__, strerror(errno));
1070
1071         old_umask = umask(0177);
1072         if (bind(control_fd, (struct sockaddr*)&addr, addr_len) == -1) {
1073                 control_fd = -1;
1074                 if (errno == EINVAL)
1075                         fatal("ControlSocket %s already exists",
1076                             options.control_path);
1077                 else
1078                         fatal("%s bind(): %s\n", __func__, strerror(errno));
1079         }
1080         umask(old_umask);
1081
1082         if (listen(control_fd, 64) == -1)
1083                 fatal("%s listen(): %s\n", __func__, strerror(errno));
1084
1085         set_nonblock(control_fd);
1086 }
1087
1088 /* request pty/x11/agent/tcpfwd/shell for channel */
1089 static void
1090 ssh_session2_setup(int id, void *arg)
1091 {
1092         extern char **environ;
1093
1094         int interactive = tty_flag;
1095         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
1096                 char *proto, *data;
1097                 /* Get reasonable local authentication information. */
1098                 x11_get_proto(&proto, &data);
1099                 /* Request forwarding with authentication spoofing. */
1100                 debug("Requesting X11 forwarding with authentication spoofing.");
1101                 x11_request_forwarding_with_spoofing(id, proto, data);
1102                 interactive = 1;
1103                 /* XXX wait for reply */
1104         }
1105
1106         check_agent_present();
1107         if (options.forward_agent) {
1108                 debug("Requesting authentication agent forwarding.");
1109                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1110                 packet_send();
1111         }
1112
1113         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1114             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1115
1116         packet_set_interactive(interactive);
1117 }
1118
1119 /* open new channel for a session */
1120 static int
1121 ssh_session2_open(void)
1122 {
1123         Channel *c;
1124         int window, packetmax, in, out, err;
1125
1126         if (stdin_null_flag) {
1127                 in = open(_PATH_DEVNULL, O_RDONLY);
1128         } else {
1129                 in = dup(STDIN_FILENO);
1130         }
1131         out = dup(STDOUT_FILENO);
1132         err = dup(STDERR_FILENO);
1133
1134         if (in < 0 || out < 0 || err < 0)
1135                 fatal("dup() in/out/err failed");
1136
1137         /* enable nonblocking unless tty */
1138         if (!isatty(in))
1139                 set_nonblock(in);
1140         if (!isatty(out))
1141                 set_nonblock(out);
1142         if (!isatty(err))
1143                 set_nonblock(err);
1144
1145         window = CHAN_SES_WINDOW_DEFAULT;
1146         packetmax = CHAN_SES_PACKET_DEFAULT;
1147         if (tty_flag) {
1148                 window >>= 1;
1149                 packetmax >>= 1;
1150         }
1151         c = channel_new(
1152             "session", SSH_CHANNEL_OPENING, in, out, err,
1153             window, packetmax, CHAN_EXTENDED_WRITE,
1154             "client-session", /*nonblock*/0);
1155
1156         debug3("ssh_session2_open: channel_new: %d", c->self);
1157
1158         channel_send_open(c->self);
1159         if (!no_shell_flag)
1160                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1161
1162         return c->self;
1163 }
1164
1165 static int
1166 ssh_session2(void)
1167 {
1168         int id = -1;
1169
1170         /* XXX should be pre-session */
1171         ssh_init_forwarding();
1172         ssh_control_listener();
1173
1174         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1175                 id = ssh_session2_open();
1176
1177         /* If requested, let ssh continue in the background. */
1178         if (fork_after_authentication_flag)
1179                 if (daemon(1, 1) < 0)
1180                         fatal("daemon() failed: %.200s", strerror(errno));
1181
1182         return client_loop(tty_flag, tty_flag ?
1183             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1184 }
1185
1186 static void
1187 load_public_identity_files(void)
1188 {
1189         char *filename;
1190         int i = 0;
1191         Key *public;
1192 #ifdef SMARTCARD
1193         Key **keys;
1194
1195         if (options.smartcard_device != NULL &&
1196             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1197             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1198                 int count = 0;
1199                 for (i = 0; keys[i] != NULL; i++) {
1200                         count++;
1201                         memmove(&options.identity_files[1], &options.identity_files[0],
1202                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1203                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1204                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1205                         options.num_identity_files++;
1206                         options.identity_keys[0] = keys[i];
1207                         options.identity_files[0] = sc_get_key_label(keys[i]);
1208                 }
1209                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1210                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1211                 i = count;
1212                 xfree(keys);
1213         }
1214 #endif /* SMARTCARD */
1215         for (; i < options.num_identity_files; i++) {
1216                 filename = tilde_expand_filename(options.identity_files[i],
1217                     original_real_uid);
1218                 public = key_load_public(filename, NULL);
1219                 debug("identity file %s type %d", filename,
1220                     public ? public->type : -1);
1221                 xfree(options.identity_files[i]);
1222                 options.identity_files[i] = filename;
1223                 options.identity_keys[i] = public;
1224         }
1225 }
1226
1227 static void
1228 control_client_sighandler(int signo)
1229 {
1230         control_client_terminate = signo;
1231 }
1232
1233 static void
1234 control_client_sigrelay(int signo)
1235 {
1236         if (control_server_pid > 1)
1237                 kill(control_server_pid, signo);
1238 }
1239
1240 static int
1241 env_permitted(char *env)
1242 {
1243         int i;
1244         char name[1024], *cp;
1245
1246         strlcpy(name, env, sizeof(name));
1247         if ((cp = strchr(name, '=')) == NULL)
1248                 return (0);
1249
1250         *cp = '\0';
1251
1252         for (i = 0; i < options.num_send_env; i++)
1253                 if (match_pattern(name, options.send_env[i]))
1254                         return (1);
1255
1256         return (0);
1257 }
1258
1259 static void
1260 control_client(const char *path)
1261 {
1262         struct sockaddr_un addr;
1263         int i, r, fd, sock, exitval, num_env, addr_len;
1264         Buffer m;
1265         char *term;
1266         extern char **environ;
1267         u_int  flags;
1268
1269         if (stdin_null_flag) {
1270                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1271                         fatal("open(/dev/null): %s", strerror(errno));
1272                 if (dup2(fd, STDIN_FILENO) == -1)
1273                         fatal("dup2: %s", strerror(errno));
1274                 if (fd > STDERR_FILENO)
1275                         close(fd);
1276         }
1277
1278         memset(&addr, '\0', sizeof(addr));
1279         addr.sun_family = AF_UNIX;
1280         addr_len = offsetof(struct sockaddr_un, sun_path) +
1281             strlen(path) + 1;
1282
1283         if (strlcpy(addr.sun_path, path,
1284             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1285                 fatal("ControlPath too long");
1286
1287         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1288                 fatal("%s socket(): %s", __func__, strerror(errno));
1289
1290         if (connect(sock, (struct sockaddr*)&addr, addr_len) == -1)
1291                 fatal("Couldn't connect to %s: %s", path, strerror(errno));
1292
1293         if ((term = getenv("TERM")) == NULL)
1294                 term = "";
1295
1296         flags = 0;
1297         if (tty_flag)
1298                 flags |= SSHMUX_FLAG_TTY;
1299         if (subsystem_flag)
1300                 flags |= SSHMUX_FLAG_SUBSYS;
1301
1302         buffer_init(&m);
1303
1304         /* Send our command to server */
1305         buffer_put_int(&m, mux_command);
1306         buffer_put_int(&m, flags);
1307         if (ssh_msg_send(sock, /* version */1, &m) == -1)
1308                 fatal("%s: msg_send", __func__);
1309         buffer_clear(&m);
1310
1311         /* Get authorisation status and PID of controlee */
1312         if (ssh_msg_recv(sock, &m) == -1)
1313                 fatal("%s: msg_recv", __func__);
1314         if (buffer_get_char(&m) != 1)
1315                 fatal("%s: wrong version", __func__);
1316         if (buffer_get_int(&m) != 1)
1317                 fatal("Connection to master denied");
1318         control_server_pid = buffer_get_int(&m);
1319
1320         buffer_clear(&m);
1321
1322         switch (mux_command) {
1323         case SSHMUX_COMMAND_ALIVE_CHECK:
1324                 fprintf(stderr, "Master running (pid=%d)\r\n",
1325                     control_server_pid);
1326                 exit(0);
1327         case SSHMUX_COMMAND_TERMINATE:
1328                 fprintf(stderr, "Exit request sent.\r\n");
1329                 exit(0);
1330         case SSHMUX_COMMAND_OPEN:
1331                 /* continue below */
1332                 break;
1333         default:
1334                 fatal("silly mux_command %d", mux_command);
1335         }
1336
1337         /* SSHMUX_COMMAND_OPEN */
1338         buffer_put_cstring(&m, term);
1339         buffer_append(&command, "\0", 1);
1340         buffer_put_cstring(&m, buffer_ptr(&command));
1341
1342         if (options.num_send_env == 0 || environ == NULL) {
1343                 buffer_put_int(&m, 0);
1344         } else {
1345                 /* Pass environment */
1346                 num_env = 0;
1347                 for (i = 0; environ[i] != NULL; i++)
1348                         if (env_permitted(environ[i]))
1349                                 num_env++; /* Count */
1350
1351                 buffer_put_int(&m, num_env);
1352
1353                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1354                         if (env_permitted(environ[i])) {
1355                                 num_env--;
1356                                 buffer_put_cstring(&m, environ[i]);
1357                         }
1358         }
1359
1360         if (ssh_msg_send(sock, /* version */1, &m) == -1)
1361                 fatal("%s: msg_send", __func__);
1362
1363         mm_send_fd(sock, STDIN_FILENO);
1364         mm_send_fd(sock, STDOUT_FILENO);
1365         mm_send_fd(sock, STDERR_FILENO);
1366
1367         /* Wait for reply, so master has a chance to gather ttymodes */
1368         buffer_clear(&m);
1369         if (ssh_msg_recv(sock, &m) == -1)
1370                 fatal("%s: msg_recv", __func__);
1371         if (buffer_get_char(&m) != 1)
1372                 fatal("%s: wrong version", __func__);
1373         buffer_free(&m);
1374
1375         signal(SIGHUP, control_client_sighandler);
1376         signal(SIGINT, control_client_sighandler);
1377         signal(SIGTERM, control_client_sighandler);
1378         signal(SIGWINCH, control_client_sigrelay);
1379
1380         if (tty_flag)
1381                 enter_raw_mode();
1382
1383         /* Stick around until the controlee closes the client_fd */
1384         exitval = 0;
1385         for (;!control_client_terminate;) {
1386                 r = read(sock, &exitval, sizeof(exitval));
1387                 if (r == 0) {
1388                         debug2("Received EOF from master");
1389                         break;
1390                 }
1391                 if (r > 0)
1392                         debug2("Received exit status from master %d", exitval);
1393                 if (r == -1 && errno != EINTR)
1394                         fatal("%s: read %s", __func__, strerror(errno));
1395         }
1396
1397         if (control_client_terminate)
1398                 debug2("Exiting on signal %d", control_client_terminate);
1399
1400         close(sock);
1401
1402         leave_raw_mode();
1403
1404         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1405                 fprintf(stderr, "Connection to master closed.\r\n");
1406
1407         exit(exitval);
1408 }