ssh.c

   1 /* $OpenBSD: ssh.c,v 1.289 2006/07/22 20:48:23 stevesk Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * Ssh client program.  This program can be used to log into a remote machine.
   7  * The software supports strong authentication, encryption, and forwarding
   8  * of X11, TCP/IP, and authentication connections.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  17  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  18  *
  19  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  20  * in Canada (German citizen).
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the above copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  *
  31  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  32  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  34  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  35  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  36  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  37  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  38  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  39  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  40  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  41  */
  42
  43 #include "includes.h"
  44
  45 #include <sys/types.h>
  46 #ifdef HAVE_SYS_STAT_H
  47 # include <sys/stat.h>
  48 #endif
  49 #include <sys/resource.h>
  50 #include <sys/ioctl.h>
  51 #include <sys/socket.h>
  52 #include <sys/un.h>
  53
  54 #include <ctype.h>
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #include <netdb.h>
  58 #ifdef HAVE_PATHS_H
  59 #include <paths.h>
  60 #endif
  61 #include <pwd.h>
  62 #include <signal.h>
  63 #include <stddef.h>
  64 #include <string.h>
  65 #include <unistd.h>
  66
  67 #include <openssl/evp.h>
  68 #include <openssl/err.h>
  69
  70 #include "ssh.h"
  71 #include "ssh1.h"
  72 #include "ssh2.h"
  73 #include "compat.h"
  74 #include "cipher.h"
  75 #include "xmalloc.h"
  76 #include "packet.h"
  77 #include "buffer.h"
  78 #include "bufaux.h"
  79 #include "channels.h"
  80 #include "key.h"
  81 #include "authfd.h"
  82 #include "authfile.h"
  83 #include "pathnames.h"
  84 #include "dispatch.h"
  85 #include "clientloop.h"
  86 #include "log.h"
  87 #include "readconf.h"
  88 #include "sshconnect.h"
  89 #include "misc.h"
  90 #include "kex.h"
  91 #include "mac.h"
  92 #include "sshpty.h"
  93 #include "match.h"
  94 #include "msg.h"
  95 #include "monitor_fdpass.h"
  96 #include "uidswap.h"
  97 #include "version.h"
  98
  99 #ifdef SMARTCARD
 100 #include "scard.h"
 101 #endif
 102
 103 extern char *__progname;
 104
 105 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
 106 int debug_flag = 0;
 107
 108 /* Flag indicating whether a tty should be allocated */
 109 int tty_flag = 0;
 110 int no_tty_flag = 0;
 111 int force_tty_flag = 0;
 112
 113 /* don't exec a shell */
 114 int no_shell_flag = 0;
 115
 116 /*
 117  * Flag indicating that nothing should be read from stdin.  This can be set
 118  * on the command line.
 119  */
 120 int stdin_null_flag = 0;
 121
 122 /*
 123  * Flag indicating that ssh should fork after authentication.  This is useful
 124  * so that the passphrase can be entered manually, and then ssh goes to the
 125  * background.
 126  */
 127 int fork_after_authentication_flag = 0;
 128
 129 /*
 130  * General data structure for command line options and options configurable
 131  * in configuration files.  See readconf.h.
 132  */
 133 Options options;
 134
 135 /* optional user configfile */
 136 char *config = NULL;
 137
 138 /*
 139  * Name of the host we are connecting to.  This is the name given on the
 140  * command line, or the HostName specified for the user-supplied name in a
 141  * configuration file.
 142  */
 143 char *host;
 144
 145 /* socket address the host resolves to */
 146 struct sockaddr_storage hostaddr;
 147
 148 /* Private host keys. */
 149 Sensitive sensitive_data;
 150
 151 /* Original real UID. */
 152 uid_t original_real_uid;
 153 uid_t original_effective_uid;
 154
 155 /* command to be executed */
 156 Buffer command;
 157
 158 /* Should we execute a command or invoke a subsystem? */
 159 int subsystem_flag = 0;
 160
 161 /* # of replies received for global requests */
 162 static int client_global_request_id = 0;
 163
 164 /* pid of proxycommand child process */
 165 pid_t proxy_command_pid = 0;
 166
 167 /* fd to control socket */
 168 int control_fd = -1;
 169
 170 /* Multiplexing control command */
 171 static u_int mux_command = 0;
 172
 173 /* Only used in control client mode */
 174 volatile sig_atomic_t control_client_terminate = 0;
 175 u_int control_server_pid = 0;
 176
 177 /* Prints a help message to the user.  This function never returns. */
 178
 179 static void
 180 usage(void)
 181 {
 182         fprintf(stderr,
 183 "usage: ssh [-1246AaCfgkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 184 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 185 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 186 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 187 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 188 "           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
 189         );
 190         exit(255);
 191 }
 192
 193 static int ssh_session(void);
 194 static int ssh_session2(void);
 195 static void load_public_identity_files(void);
 196 static void control_client(const char *path);
 197
 198 /*
 199  * Main program for the ssh client.
 200  */
 201 int
 202 main(int ac, char **av)
 203 {
 204         int i, opt, exit_status;
 205         char *p, *cp, *line, buf[256];
 206         struct stat st;
 207         struct passwd *pw;
 208         int dummy;
 209         extern int optind, optreset;
 210         extern char *optarg;
 211         struct servent *sp;
 212         Forward fwd;
 213
 214         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 215         sanitise_stdfd();
 216
 217         __progname = ssh_get_progname(av[0]);
 218         init_rng();
 219
 220         /*
 221          * Save the original real uid.  It will be needed later (uid-swapping
 222          * may clobber the real uid).
 223          */
 224         original_real_uid = getuid();
 225         original_effective_uid = geteuid();
 226
 227         /*
 228          * Use uid-swapping to give up root privileges for the duration of
 229          * option processing.  We will re-instantiate the rights when we are
 230          * ready to create the privileged port, and will permanently drop
 231          * them when the port has been created (actually, when the connection
 232          * has been made, as we may need to create the port several times).
 233          */
 234         PRIV_END;
 235
 236 #ifdef HAVE_SETRLIMIT
 237         /* If we are installed setuid root be careful to not drop core. */
 238         if (original_real_uid != original_effective_uid) {
 239                 struct rlimit rlim;
 240                 rlim.rlim_cur = rlim.rlim_max = 0;
 241                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 242                         fatal("setrlimit failed: %.100s", strerror(errno));
 243         }
 244 #endif
 245         /* Get user data. */
 246         pw = getpwuid(original_real_uid);
 247         if (!pw) {
 248                 logit("You don't exist, go away!");
 249                 exit(255);
 250         }
 251         /* Take a copy of the returned structure. */
 252         pw = pwcopy(pw);
 253
 254         /*
 255          * Set our umask to something reasonable, as some files are created
 256          * with the default umask.  This will make them world-readable but
 257          * writable only by the owner, which is ok for all files for which we
 258          * don't set the modes explicitly.
 259          */
 260         umask(022);
 261
 262         /* Initialize option structure to indicate that no values have been set. */
 263         initialize_options(&options);
 264
 265         /* Parse command-line arguments. */
 266         host = NULL;
 267
 268  again:
 269         while ((opt = getopt(ac, av,
 270             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:MNO:PR:S:TVw:XY")) != -1) {
 271                 switch (opt) {
 272                 case '1':
 273                         options.protocol = SSH_PROTO_1;
 274                         break;
 275                 case '2':
 276                         options.protocol = SSH_PROTO_2;
 277                         break;
 278                 case '4':
 279                         options.address_family = AF_INET;
 280                         break;
 281                 case '6':
 282                         options.address_family = AF_INET6;
 283                         break;
 284                 case 'n':
 285                         stdin_null_flag = 1;
 286                         break;
 287                 case 'f':
 288                         fork_after_authentication_flag = 1;
 289                         stdin_null_flag = 1;
 290                         break;
 291                 case 'x':
 292                         options.forward_x11 = 0;
 293                         break;
 294                 case 'X':
 295                         options.forward_x11 = 1;
 296                         break;
 297                 case 'Y':
 298                         options.forward_x11 = 1;
 299                         options.forward_x11_trusted = 1;
 300                         break;
 301                 case 'g':
 302                         options.gateway_ports = 1;
 303                         break;
 304                 case 'O':
 305                         if (strcmp(optarg, "check") == 0)
 306                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 307                         else if (strcmp(optarg, "exit") == 0)
 308                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 309                         else
 310                                 fatal("Invalid multiplex command.");
 311                         break;
 312                 case 'P':       /* deprecated */
 313                         options.use_privileged_port = 0;
 314                         break;
 315                 case 'a':
 316                         options.forward_agent = 0;
 317                         break;
 318                 case 'A':
 319                         options.forward_agent = 1;
 320                         break;
 321                 case 'k':
 322                         options.gss_deleg_creds = 0;
 323                         break;
 324                 case 'i':
 325                         if (stat(optarg, &st) < 0) {
 326                                 fprintf(stderr, "Warning: Identity file %s "
 327                                     "not accessible: %s.\n", optarg,
 328                                     strerror(errno));
 329                                 break;
 330                         }
 331                         if (options.num_identity_files >=
 332                             SSH_MAX_IDENTITY_FILES)
 333                                 fatal("Too many identity files specified "
 334                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 335                         options.identity_files[options.num_identity_files++] =
 336                             xstrdup(optarg);
 337                         break;
 338                 case 'I':
 339 #ifdef SMARTCARD
 340                         options.smartcard_device = xstrdup(optarg);
 341 #else
 342                         fprintf(stderr, "no support for smartcards.\n");
 343 #endif
 344                         break;
 345                 case 't':
 346                         if (tty_flag)
 347                                 force_tty_flag = 1;
 348                         tty_flag = 1;
 349                         break;
 350                 case 'v':
 351                         if (debug_flag == 0) {
 352                                 debug_flag = 1;
 353                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 354                         } else {
 355                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 356                                         options.log_level++;
 357                                 break;
 358                         }
 359                         /* FALLTHROUGH */
 360                 case 'V':
 361                         fprintf(stderr, "%s, %s\n",
 362                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 363                         if (opt == 'V')
 364                                 exit(0);
 365                         break;
 366                 case 'w':
 367                         if (options.tun_open == -1)
 368                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 369                         options.tun_local = a2tun(optarg, &options.tun_remote);
 370                         if (options.tun_local == SSH_TUNID_ERR) {
 371                                 fprintf(stderr, "Bad tun device '%s'\n", optarg);
 372                                 exit(255);
 373                         }
 374                         break;
 375                 case 'q':
 376                         options.log_level = SYSLOG_LEVEL_QUIET;
 377                         break;
 378                 case 'e':
 379                         if (optarg[0] == '^' && optarg[2] == 0 &&
 380                             (u_char) optarg[1] >= 64 &&
 381                             (u_char) optarg[1] < 128)
 382                                 options.escape_char = (u_char) optarg[1] & 31;
 383                         else if (strlen(optarg) == 1)
 384                                 options.escape_char = (u_char) optarg[0];
 385                         else if (strcmp(optarg, "none") == 0)
 386                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 387                         else {
 388                                 fprintf(stderr, "Bad escape character '%s'.\n",
 389                                     optarg);
 390                                 exit(255);
 391                         }
 392                         break;
 393                 case 'c':
 394                         if (ciphers_valid(optarg)) {
 395                                 /* SSH2 only */
 396                                 options.ciphers = xstrdup(optarg);
 397                                 options.cipher = SSH_CIPHER_INVALID;
 398                         } else {
 399                                 /* SSH1 only */
 400                                 options.cipher = cipher_number(optarg);
 401                                 if (options.cipher == -1) {
 402                                         fprintf(stderr,
 403                                             "Unknown cipher type '%s'\n",
 404                                             optarg);
 405                                         exit(255);
 406                                 }
 407                                 if (options.cipher == SSH_CIPHER_3DES)
 408                                         options.ciphers = "3des-cbc";
 409                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 410                                         options.ciphers = "blowfish-cbc";
 411                                 else
 412                                         options.ciphers = (char *)-1;
 413                         }
 414                         break;
 415                 case 'm':
 416                         if (mac_valid(optarg))
 417                                 options.macs = xstrdup(optarg);
 418                         else {
 419                                 fprintf(stderr, "Unknown mac type '%s'\n",
 420                                     optarg);
 421                                 exit(255);
 422                         }
 423                         break;
 424                 case 'M':
 425                         if (options.control_master == SSHCTL_MASTER_YES)
 426                                 options.control_master = SSHCTL_MASTER_ASK;
 427                         else
 428                                 options.control_master = SSHCTL_MASTER_YES;
 429                         break;
 430                 case 'p':
 431                         options.port = a2port(optarg);
 432                         if (options.port == 0) {
 433                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 434                                 exit(255);
 435                         }
 436                         break;
 437                 case 'l':
 438                         options.user = optarg;
 439                         break;
 440
 441                 case 'L':
 442                         if (parse_forward(&fwd, optarg))
 443                                 add_local_forward(&options, &fwd);
 444                         else {
 445                                 fprintf(stderr,
 446                                     "Bad local forwarding specification '%s'\n",
 447                                     optarg);
 448                                 exit(255);
 449                         }
 450                         break;
 451
 452                 case 'R':
 453                         if (parse_forward(&fwd, optarg)) {
 454                                 add_remote_forward(&options, &fwd);
 455                         } else {
 456                                 fprintf(stderr,
 457                                     "Bad remote forwarding specification "
 458                                     "'%s'\n", optarg);
 459                                 exit(255);
 460                         }
 461                         break;
 462
 463                 case 'D':
 464                         cp = p = xstrdup(optarg);
 465                         memset(&fwd, '\0', sizeof(fwd));
 466                         fwd.connect_host = "socks";
 467                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 468                                 fprintf(stderr, "Bad dynamic forwarding "
 469                                     "specification '%.100s'\n", optarg);
 470                                 exit(255);
 471                         }
 472                         if (cp != NULL) {
 473                                 fwd.listen_port = a2port(cp);
 474                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 475                         } else {
 476                                 fwd.listen_port = a2port(fwd.listen_host);
 477                                 fwd.listen_host = NULL;
 478                         }
 479
 480                         if (fwd.listen_port == 0) {
 481                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 482                                     optarg);
 483                                 exit(255);
 484                         }
 485                         add_local_forward(&options, &fwd);
 486                         xfree(p);
 487                         break;
 488
 489                 case 'C':
 490                         options.compression = 1;
 491                         break;
 492                 case 'N':
 493                         no_shell_flag = 1;
 494                         no_tty_flag = 1;
 495                         break;
 496                 case 'T':
 497                         no_tty_flag = 1;
 498                         break;
 499                 case 'o':
 500                         dummy = 1;
 501                         line = xstrdup(optarg);
 502                         if (process_config_line(&options, host ? host : "",
 503                             line, "command-line", 0, &dummy) != 0)
 504                                 exit(255);
 505                         xfree(line);
 506                         break;
 507                 case 's':
 508                         subsystem_flag = 1;
 509                         break;
 510                 case 'S':
 511                         if (options.control_path != NULL)
 512                                 free(options.control_path);
 513                         options.control_path = xstrdup(optarg);
 514                         break;
 515                 case 'b':
 516                         options.bind_address = optarg;
 517                         break;
 518                 case 'F':
 519                         config = optarg;
 520                         break;
 521                 default:
 522                         usage();
 523                 }
 524         }
 525
 526         ac -= optind;
 527         av += optind;
 528
 529         if (ac > 0 && !host && **av != '-') {
 530                 if (strrchr(*av, '@')) {
 531                         p = xstrdup(*av);
 532                         cp = strrchr(p, '@');
 533                         if (cp == NULL || cp == p)
 534                                 usage();
 535                         options.user = p;
 536                         *cp = '\0';
 537                         host = ++cp;
 538                 } else
 539                         host = *av;
 540                 if (ac > 1) {
 541                         optind = optreset = 1;
 542                         goto again;
 543                 }
 544                 ac--, av++;
 545         }
 546
 547         /* Check that we got a host name. */
 548         if (!host)
 549                 usage();
 550
 551         SSLeay_add_all_algorithms();
 552         ERR_load_crypto_strings();
 553
 554         /* Initialize the command to execute on remote host. */
 555         buffer_init(&command);
 556
 557         /*
 558          * Save the command to execute on the remote host in a buffer. There
 559          * is no limit on the length of the command, except by the maximum
 560          * packet size.  Also sets the tty flag if there is no command.
 561          */
 562         if (!ac) {
 563                 /* No command specified - execute shell on a tty. */
 564                 tty_flag = 1;
 565                 if (subsystem_flag) {
 566                         fprintf(stderr,
 567                             "You must specify a subsystem to invoke.\n");
 568                         usage();
 569                 }
 570         } else {
 571                 /* A command has been specified.  Store it into the buffer. */
 572                 for (i = 0; i < ac; i++) {
 573                         if (i)
 574                                 buffer_append(&command, " ", 1);
 575                         buffer_append(&command, av[i], strlen(av[i]));
 576                 }
 577         }
 578
 579         /* Cannot fork to background if no command. */
 580         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 581                 fatal("Cannot fork into background without a command to execute.");
 582
 583         /* Allocate a tty by default if no command specified. */
 584         if (buffer_len(&command) == 0)
 585                 tty_flag = 1;
 586
 587         /* Force no tty */
 588         if (no_tty_flag)
 589                 tty_flag = 0;
 590         /* Do not allocate a tty if stdin is not a tty. */
 591         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 592                 if (tty_flag)
 593                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 594                 tty_flag = 0;
 595         }
 596
 597         /*
 598          * Initialize "log" output.  Since we are the client all output
 599          * actually goes to stderr.
 600          */
 601         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 602             SYSLOG_FACILITY_USER, 1);
 603
 604         /*
 605          * Read per-user configuration file.  Ignore the system wide config
 606          * file if the user specifies a config file on the command line.
 607          */
 608         if (config != NULL) {
 609                 if (!read_config_file(config, host, &options, 0))
 610                         fatal("Can't open user config file %.100s: "
 611                             "%.100s", config, strerror(errno));
 612         } else  {
 613                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 614                     _PATH_SSH_USER_CONFFILE);
 615                 (void)read_config_file(buf, host, &options, 1);
 616
 617                 /* Read systemwide configuration file after use config. */
 618                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 619                     &options, 0);
 620         }
 621
 622         /* Fill configuration defaults. */
 623         fill_default_options(&options);
 624
 625         channel_set_af(options.address_family);
 626
 627         /* reinit */
 628         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 629
 630         seed_rng();
 631
 632         if (options.user == NULL)
 633                 options.user = xstrdup(pw->pw_name);
 634
 635         if (options.hostname != NULL)
 636                 host = options.hostname;
 637
 638         /* force lowercase for hostkey matching */
 639         if (options.host_key_alias != NULL) {
 640                 for (p = options.host_key_alias; *p; p++)
 641                         if (isupper(*p))
 642                                 *p = (char)tolower(*p);
 643         }
 644
 645         /* Get default port if port has not been set. */
 646         if (options.port == 0) {
 647                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 648                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 649         }
 650
 651         if (options.proxy_command != NULL &&
 652             strcmp(options.proxy_command, "none") == 0)
 653                 options.proxy_command = NULL;
 654         if (options.control_path != NULL &&
 655             strcmp(options.control_path, "none") == 0)
 656                 options.control_path = NULL;
 657
 658         if (options.control_path != NULL) {
 659                 char thishost[NI_MAXHOST];
 660
 661                 if (gethostname(thishost, sizeof(thishost)) == -1)
 662                         fatal("gethostname: %s", strerror(errno));
 663                 snprintf(buf, sizeof(buf), "%d", options.port);
 664                 cp = tilde_expand_filename(options.control_path,
 665                     original_real_uid);
 666                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 667                     "r", options.user, "l", thishost, (char *)NULL);
 668                 xfree(cp);
 669         }
 670         if (mux_command != 0 && options.control_path == NULL)
 671                 fatal("No ControlPath specified for \"-O\" command");
 672         if (options.control_path != NULL)
 673                 control_client(options.control_path);
 674
 675         /* Open a connection to the remote host. */
 676         if (ssh_connect(host, &hostaddr, options.port,
 677             options.address_family, options.connection_attempts,
 678 #ifdef HAVE_CYGWIN
 679             options.use_privileged_port,
 680 #else
 681             original_effective_uid == 0 && options.use_privileged_port,
 682 #endif
 683             options.proxy_command) != 0)
 684                 exit(255);
 685
 686         /*
 687          * If we successfully made the connection, load the host private key
 688          * in case we will need it later for combined rsa-rhosts
 689          * authentication. This must be done before releasing extra
 690          * privileges, because the file is only readable by root.
 691          * If we cannot access the private keys, load the public keys
 692          * instead and try to execute the ssh-keysign helper instead.
 693          */
 694         sensitive_data.nkeys = 0;
 695         sensitive_data.keys = NULL;
 696         sensitive_data.external_keysign = 0;
 697         if (options.rhosts_rsa_authentication ||
 698             options.hostbased_authentication) {
 699                 sensitive_data.nkeys = 3;
 700                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 701                     sizeof(Key));
 702
 703                 PRIV_START;
 704                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 705                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 706                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 707                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 708                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 709                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 710                 PRIV_END;
 711
 712                 if (options.hostbased_authentication == 1 &&
 713                     sensitive_data.keys[0] == NULL &&
 714                     sensitive_data.keys[1] == NULL &&
 715                     sensitive_data.keys[2] == NULL) {
 716                         sensitive_data.keys[1] = key_load_public(
 717                             _PATH_HOST_DSA_KEY_FILE, NULL);
 718                         sensitive_data.keys[2] = key_load_public(
 719                             _PATH_HOST_RSA_KEY_FILE, NULL);
 720                         sensitive_data.external_keysign = 1;
 721                 }
 722         }
 723         /*
 724          * Get rid of any extra privileges that we may have.  We will no
 725          * longer need them.  Also, extra privileges could make it very hard
 726          * to read identity files and other non-world-readable files from the
 727          * user's home directory if it happens to be on a NFS volume where
 728          * root is mapped to nobody.
 729          */
 730         if (original_effective_uid == 0) {
 731                 PRIV_START;
 732                 permanently_set_uid(pw);
 733         }
 734
 735         /*
 736          * Now that we are back to our own permissions, create ~/.ssh
 737          * directory if it doesn't already exist.
 738          */
 739         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 740         if (stat(buf, &st) < 0)
 741                 if (mkdir(buf, 0700) < 0)
 742                         error("Could not create directory '%.200s'.", buf);
 743
 744         /* load options.identity_files */
 745         load_public_identity_files();
 746
 747         /* Expand ~ in known host file names. */
 748         /* XXX mem-leaks: */
 749         options.system_hostfile =
 750             tilde_expand_filename(options.system_hostfile, original_real_uid);
 751         options.user_hostfile =
 752             tilde_expand_filename(options.user_hostfile, original_real_uid);
 753         options.system_hostfile2 =
 754             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 755         options.user_hostfile2 =
 756             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 757
 758         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 759
 760         /* Log into the remote system.  This never returns if the login fails. */
 761         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 762
 763         /* We no longer need the private host keys.  Clear them now. */
 764         if (sensitive_data.nkeys != 0) {
 765                 for (i = 0; i < sensitive_data.nkeys; i++) {
 766                         if (sensitive_data.keys[i] != NULL) {
 767                                 /* Destroys contents safely */
 768                                 debug3("clear hostkey %d", i);
 769                                 key_free(sensitive_data.keys[i]);
 770                                 sensitive_data.keys[i] = NULL;
 771                         }
 772                 }
 773                 xfree(sensitive_data.keys);
 774         }
 775         for (i = 0; i < options.num_identity_files; i++) {
 776                 if (options.identity_files[i]) {
 777                         xfree(options.identity_files[i]);
 778                         options.identity_files[i] = NULL;
 779                 }
 780                 if (options.identity_keys[i]) {
 781                         key_free(options.identity_keys[i]);
 782                         options.identity_keys[i] = NULL;
 783                 }
 784         }
 785
 786         exit_status = compat20 ? ssh_session2() : ssh_session();
 787         packet_close();
 788
 789         if (options.control_path != NULL && control_fd != -1)
 790                 unlink(options.control_path);
 791
 792         /*
 793          * Send SIGHUP to proxy command if used. We don't wait() in
 794          * case it hangs and instead rely on init to reap the child
 795          */
 796         if (proxy_command_pid > 1)
 797                 kill(proxy_command_pid, SIGHUP);
 798
 799         return exit_status;
 800 }
 801
 802 static void
 803 ssh_init_forwarding(void)
 804 {
 805         int success = 0;
 806         int i;
 807
 808         /* Initiate local TCP/IP port forwardings. */
 809         for (i = 0; i < options.num_local_forwards; i++) {
 810                 debug("Local connections to %.200s:%d forwarded to remote "
 811                     "address %.200s:%d",
 812                     (options.local_forwards[i].listen_host == NULL) ?
 813                     (options.gateway_ports ? "*" : "LOCALHOST") :
 814                     options.local_forwards[i].listen_host,
 815                     options.local_forwards[i].listen_port,
 816                     options.local_forwards[i].connect_host,
 817                     options.local_forwards[i].connect_port);
 818                 success += channel_setup_local_fwd_listener(
 819                     options.local_forwards[i].listen_host,
 820                     options.local_forwards[i].listen_port,
 821                     options.local_forwards[i].connect_host,
 822                     options.local_forwards[i].connect_port,
 823                     options.gateway_ports);
 824         }
 825         if (i > 0 && success != i && options.exit_on_forward_failure)
 826                 fatal("Could not request local forwarding.");
 827         if (i > 0 && success == 0)
 828                 error("Could not request local forwarding.");
 829
 830         /* Initiate remote TCP/IP port forwardings. */
 831         for (i = 0; i < options.num_remote_forwards; i++) {
 832                 debug("Remote connections from %.200s:%d forwarded to "
 833                     "local address %.200s:%d",
 834                     (options.remote_forwards[i].listen_host == NULL) ?
 835                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 836                     options.remote_forwards[i].listen_port,
 837                     options.remote_forwards[i].connect_host,
 838                     options.remote_forwards[i].connect_port);
 839                 if (channel_request_remote_forwarding(
 840                     options.remote_forwards[i].listen_host,
 841                     options.remote_forwards[i].listen_port,
 842                     options.remote_forwards[i].connect_host,
 843                     options.remote_forwards[i].connect_port) < 0) {
 844                         if (options.exit_on_forward_failure)
 845                                 fatal("Could not request remote forwarding.");
 846                         else
 847                                 logit("Warning: Could not request remote "
 848                                     "forwarding.");
 849                 }
 850         }
 851 }
 852
 853 static void
 854 check_agent_present(void)
 855 {
 856         if (options.forward_agent) {
 857                 /* Clear agent forwarding if we don't have an agent. */
 858                 if (!ssh_agent_present())
 859                         options.forward_agent = 0;
 860         }
 861 }
 862
 863 static int
 864 ssh_session(void)
 865 {
 866         int type;
 867         int interactive = 0;
 868         int have_tty = 0;
 869         struct winsize ws;
 870         char *cp;
 871         const char *display;
 872
 873         /* Enable compression if requested. */
 874         if (options.compression) {
 875                 debug("Requesting compression at level %d.", options.compression_level);
 876
 877                 if (options.compression_level < 1 || options.compression_level > 9)
 878                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 879
 880                 /* Send the request. */
 881                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 882                 packet_put_int(options.compression_level);
 883                 packet_send();
 884                 packet_write_wait();
 885                 type = packet_read();
 886                 if (type == SSH_SMSG_SUCCESS)
 887                         packet_start_compression(options.compression_level);
 888                 else if (type == SSH_SMSG_FAILURE)
 889                         logit("Warning: Remote host refused compression.");
 890                 else
 891                         packet_disconnect("Protocol error waiting for compression response.");
 892         }
 893         /* Allocate a pseudo tty if appropriate. */
 894         if (tty_flag) {
 895                 debug("Requesting pty.");
 896
 897                 /* Start the packet. */
 898                 packet_start(SSH_CMSG_REQUEST_PTY);
 899
 900                 /* Store TERM in the packet.  There is no limit on the
 901                    length of the string. */
 902                 cp = getenv("TERM");
 903                 if (!cp)
 904                         cp = "";
 905                 packet_put_cstring(cp);
 906
 907                 /* Store window size in the packet. */
 908                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 909                         memset(&ws, 0, sizeof(ws));
 910                 packet_put_int((u_int)ws.ws_row);
 911                 packet_put_int((u_int)ws.ws_col);
 912                 packet_put_int((u_int)ws.ws_xpixel);
 913                 packet_put_int((u_int)ws.ws_ypixel);
 914
 915                 /* Store tty modes in the packet. */
 916                 tty_make_modes(fileno(stdin), NULL);
 917
 918                 /* Send the packet, and wait for it to leave. */
 919                 packet_send();
 920                 packet_write_wait();
 921
 922                 /* Read response from the server. */
 923                 type = packet_read();
 924                 if (type == SSH_SMSG_SUCCESS) {
 925                         interactive = 1;
 926                         have_tty = 1;
 927                 } else if (type == SSH_SMSG_FAILURE)
 928                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 929                 else
 930                         packet_disconnect("Protocol error waiting for pty request response.");
 931         }
 932         /* Request X11 forwarding if enabled and DISPLAY is set. */
 933         display = getenv("DISPLAY");
 934         if (options.forward_x11 && display != NULL) {
 935                 char *proto, *data;
 936                 /* Get reasonable local authentication information. */
 937                 client_x11_get_proto(display, options.xauth_location,
 938                     options.forward_x11_trusted, &proto, &data);
 939                 /* Request forwarding with authentication spoofing. */
 940                 debug("Requesting X11 forwarding with authentication spoofing.");
 941                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 942
 943                 /* Read response from the server. */
 944                 type = packet_read();
 945                 if (type == SSH_SMSG_SUCCESS) {
 946                         interactive = 1;
 947                 } else if (type == SSH_SMSG_FAILURE) {
 948                         logit("Warning: Remote host denied X11 forwarding.");
 949                 } else {
 950                         packet_disconnect("Protocol error waiting for X11 forwarding");
 951                 }
 952         }
 953         /* Tell the packet module whether this is an interactive session. */
 954         packet_set_interactive(interactive);
 955
 956         /* Request authentication agent forwarding if appropriate. */
 957         check_agent_present();
 958
 959         if (options.forward_agent) {
 960                 debug("Requesting authentication agent forwarding.");
 961                 auth_request_forwarding();
 962
 963                 /* Read response from the server. */
 964                 type = packet_read();
 965                 packet_check_eom();
 966                 if (type != SSH_SMSG_SUCCESS)
 967                         logit("Warning: Remote host denied authentication agent forwarding.");
 968         }
 969
 970         /* Initiate port forwardings. */
 971         ssh_init_forwarding();
 972
 973         /* If requested, let ssh continue in the background. */
 974         if (fork_after_authentication_flag)
 975                 if (daemon(1, 1) < 0)
 976                         fatal("daemon() failed: %.200s", strerror(errno));
 977
 978         /*
 979          * If a command was specified on the command line, execute the
 980          * command now. Otherwise request the server to start a shell.
 981          */
 982         if (buffer_len(&command) > 0) {
 983                 int len = buffer_len(&command);
 984                 if (len > 900)
 985                         len = 900;
 986                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 987                 packet_start(SSH_CMSG_EXEC_CMD);
 988                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 989                 packet_send();
 990                 packet_write_wait();
 991         } else {
 992                 debug("Requesting shell.");
 993                 packet_start(SSH_CMSG_EXEC_SHELL);
 994                 packet_send();
 995                 packet_write_wait();
 996         }
 997
 998         /* Enter the interactive session. */
 999         return client_loop(have_tty, tty_flag ?
1000             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1001 }
1002
1003 static void
1004 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1005 {
1006         int id, len;
1007
1008         id = packet_get_int();
1009         len = buffer_len(&command);
1010         if (len > 900)
1011                 len = 900;
1012         packet_check_eom();
1013         if (type == SSH2_MSG_CHANNEL_FAILURE)
1014                 fatal("Request for subsystem '%.*s' failed on channel %d",
1015                     len, (u_char *)buffer_ptr(&command), id);
1016 }
1017
1018 void
1019 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1020 {
1021         int i;
1022
1023         i = client_global_request_id++;
1024         if (i >= options.num_remote_forwards)
1025                 return;
1026         debug("remote forward %s for: listen %d, connect %s:%d",
1027             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1028             options.remote_forwards[i].listen_port,
1029             options.remote_forwards[i].connect_host,
1030             options.remote_forwards[i].connect_port);
1031         if (type == SSH2_MSG_REQUEST_FAILURE) {
1032                 if (options.exit_on_forward_failure)
1033                         fatal("Error: remote port forwarding failed for "
1034                             "listen port %d",
1035                             options.remote_forwards[i].listen_port);
1036                 else
1037                         logit("Warning: remote port forwarding failed for "
1038                             "listen port %d",
1039                             options.remote_forwards[i].listen_port);
1040         }
1041 }
1042
1043 static void
1044 ssh_control_listener(void)
1045 {
1046         struct sockaddr_un addr;
1047         mode_t old_umask;
1048         int addr_len;
1049
1050         if (options.control_path == NULL ||
1051             options.control_master == SSHCTL_MASTER_NO)
1052                 return;
1053
1054         debug("setting up multiplex master socket");
1055
1056         memset(&addr, '\0', sizeof(addr));
1057         addr.sun_family = AF_UNIX;
1058         addr_len = offsetof(struct sockaddr_un, sun_path) +
1059             strlen(options.control_path) + 1;
1060
1061         if (strlcpy(addr.sun_path, options.control_path,
1062             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1063                 fatal("ControlPath too long");
1064
1065         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1066                 fatal("%s socket(): %s", __func__, strerror(errno));
1067
1068         old_umask = umask(0177);
1069         if (bind(control_fd, (struct sockaddr *)&addr, addr_len) == -1) {
1070                 control_fd = -1;
1071                 if (errno == EINVAL || errno == EADDRINUSE)
1072                         fatal("ControlSocket %s already exists",
1073                             options.control_path);
1074                 else
1075                         fatal("%s bind(): %s", __func__, strerror(errno));
1076         }
1077         umask(old_umask);
1078
1079         if (listen(control_fd, 64) == -1)
1080                 fatal("%s listen(): %s", __func__, strerror(errno));
1081
1082         set_nonblock(control_fd);
1083 }
1084
1085 /* request pty/x11/agent/tcpfwd/shell for channel */
1086 static void
1087 ssh_session2_setup(int id, void *arg)
1088 {
1089         extern char **environ;
1090         const char *display;
1091         int interactive = tty_flag;
1092
1093         display = getenv("DISPLAY");
1094         if (options.forward_x11 && display != NULL) {
1095                 char *proto, *data;
1096                 /* Get reasonable local authentication information. */
1097                 client_x11_get_proto(display, options.xauth_location,
1098                     options.forward_x11_trusted, &proto, &data);
1099                 /* Request forwarding with authentication spoofing. */
1100                 debug("Requesting X11 forwarding with authentication spoofing.");
1101                 x11_request_forwarding_with_spoofing(id, display, 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         if (options.tun_open != SSH_TUNMODE_NO) {
1114                 Channel *c;
1115                 int fd;
1116
1117                 debug("Requesting tun.");
1118                 if ((fd = tun_open(options.tun_local,
1119                     options.tun_open)) >= 0) {
1120                         c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1121                             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1122                             0, "tun", 1);
1123                         c->datagram = 1;
1124 #if defined(SSH_TUN_FILTER)
1125                         if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
1126                                 channel_register_filter(c->self, sys_tun_infilter,
1127                                     sys_tun_outfilter);
1128 #endif
1129                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1130                         packet_put_cstring("tun@openssh.com");
1131                         packet_put_int(c->self);
1132                         packet_put_int(c->local_window_max);
1133                         packet_put_int(c->local_maxpacket);
1134                         packet_put_int(options.tun_open);
1135                         packet_put_int(options.tun_remote);
1136                         packet_send();
1137                 }
1138         }
1139
1140         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1141             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1142
1143         packet_set_interactive(interactive);
1144 }
1145
1146 /* open new channel for a session */
1147 static int
1148 ssh_session2_open(void)
1149 {
1150         Channel *c;
1151         int window, packetmax, in, out, err;
1152
1153         if (stdin_null_flag) {
1154                 in = open(_PATH_DEVNULL, O_RDONLY);
1155         } else {
1156                 in = dup(STDIN_FILENO);
1157         }
1158         out = dup(STDOUT_FILENO);
1159         err = dup(STDERR_FILENO);
1160
1161         if (in < 0 || out < 0 || err < 0)
1162                 fatal("dup() in/out/err failed");
1163
1164         /* enable nonblocking unless tty */
1165         if (!isatty(in))
1166                 set_nonblock(in);
1167         if (!isatty(out))
1168                 set_nonblock(out);
1169         if (!isatty(err))
1170                 set_nonblock(err);
1171
1172         window = CHAN_SES_WINDOW_DEFAULT;
1173         packetmax = CHAN_SES_PACKET_DEFAULT;
1174         if (tty_flag) {
1175                 window >>= 1;
1176                 packetmax >>= 1;
1177         }
1178         c = channel_new(
1179             "session", SSH_CHANNEL_OPENING, in, out, err,
1180             window, packetmax, CHAN_EXTENDED_WRITE,
1181             "client-session", /*nonblock*/0);
1182
1183         debug3("ssh_session2_open: channel_new: %d", c->self);
1184
1185         channel_send_open(c->self);
1186         if (!no_shell_flag)
1187                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1188
1189         return c->self;
1190 }
1191
1192 static int
1193 ssh_session2(void)
1194 {
1195         int id = -1;
1196
1197         /* XXX should be pre-session */
1198         ssh_init_forwarding();
1199         ssh_control_listener();
1200
1201         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1202                 id = ssh_session2_open();
1203
1204         /* Execute a local command */
1205         if (options.local_command != NULL &&
1206             options.permit_local_command)
1207                 ssh_local_cmd(options.local_command);
1208
1209         /* If requested, let ssh continue in the background. */
1210         if (fork_after_authentication_flag)
1211                 if (daemon(1, 1) < 0)
1212                         fatal("daemon() failed: %.200s", strerror(errno));
1213
1214         return client_loop(tty_flag, tty_flag ?
1215             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1216 }
1217
1218 static void
1219 load_public_identity_files(void)
1220 {
1221         char *filename, *cp, thishost[NI_MAXHOST];
1222         int i = 0;
1223         Key *public;
1224         struct passwd *pw;
1225 #ifdef SMARTCARD
1226         Key **keys;
1227
1228         if (options.smartcard_device != NULL &&
1229             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1230             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1231                 int count = 0;
1232                 for (i = 0; keys[i] != NULL; i++) {
1233                         count++;
1234                         memmove(&options.identity_files[1], &options.identity_files[0],
1235                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1236                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1237                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1238                         options.num_identity_files++;
1239                         options.identity_keys[0] = keys[i];
1240                         options.identity_files[0] = sc_get_key_label(keys[i]);
1241                 }
1242                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1243                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1244                 i = count;
1245                 xfree(keys);
1246         }
1247 #endif /* SMARTCARD */
1248         if ((pw = getpwuid(original_real_uid)) == NULL)
1249                 fatal("load_public_identity_files: getpwuid failed");
1250         if (gethostname(thishost, sizeof(thishost)) == -1)
1251                 fatal("load_public_identity_files: gethostname: %s",
1252                     strerror(errno));
1253         for (; i < options.num_identity_files; i++) {
1254                 cp = tilde_expand_filename(options.identity_files[i],
1255                     original_real_uid);
1256                 filename = percent_expand(cp, "d", pw->pw_dir,
1257                     "u", pw->pw_name, "l", thishost, "h", host,
1258                     "r", options.user, (char *)NULL);
1259                 xfree(cp);
1260                 public = key_load_public(filename, NULL);
1261                 debug("identity file %s type %d", filename,
1262                     public ? public->type : -1);
1263                 xfree(options.identity_files[i]);
1264                 options.identity_files[i] = filename;
1265                 options.identity_keys[i] = public;
1266         }
1267 }
1268
1269 static void
1270 control_client_sighandler(int signo)
1271 {
1272         control_client_terminate = signo;
1273 }
1274
1275 static void
1276 control_client_sigrelay(int signo)
1277 {
1278         if (control_server_pid > 1)
1279                 kill(control_server_pid, signo);
1280 }
1281
1282 static int
1283 env_permitted(char *env)
1284 {
1285         int i, ret;
1286         char name[1024], *cp;
1287
1288         if ((cp = strchr(env, '=')) == NULL || cp == env)
1289                 return (0);
1290         ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
1291         if (ret <= 0 || (size_t)ret >= sizeof(name))
1292                 fatal("env_permitted: name '%.100s...' too long", env);
1293
1294         for (i = 0; i < options.num_send_env; i++)
1295                 if (match_pattern(name, options.send_env[i]))
1296                         return (1);
1297
1298         return (0);
1299 }
1300
1301 static void
1302 control_client(const char *path)
1303 {
1304         struct sockaddr_un addr;
1305         int i, r, fd, sock, exitval, num_env, addr_len;
1306         Buffer m;
1307         char *term;
1308         extern char **environ;
1309         u_int  flags;
1310
1311         if (mux_command == 0)
1312                 mux_command = SSHMUX_COMMAND_OPEN;
1313
1314         switch (options.control_master) {
1315         case SSHCTL_MASTER_AUTO:
1316         case SSHCTL_MASTER_AUTO_ASK:
1317                 debug("auto-mux: Trying existing master");
1318                 /* FALLTHROUGH */
1319         case SSHCTL_MASTER_NO:
1320                 break;
1321         default:
1322                 return;
1323         }
1324
1325         memset(&addr, '\0', sizeof(addr));
1326         addr.sun_family = AF_UNIX;
1327         addr_len = offsetof(struct sockaddr_un, sun_path) +
1328             strlen(path) + 1;
1329
1330         if (strlcpy(addr.sun_path, path,
1331             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1332                 fatal("ControlPath too long");
1333
1334         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1335                 fatal("%s socket(): %s", __func__, strerror(errno));
1336
1337         if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) {
1338                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1339                         fatal("Control socket connect(%.100s): %s", path,
1340                             strerror(errno));
1341                 }
1342                 if (errno == ENOENT)
1343                         debug("Control socket \"%.100s\" does not exist", path);
1344                 else {
1345                         error("Control socket connect(%.100s): %s", path,
1346                             strerror(errno));
1347                 }
1348                 close(sock);
1349                 return;
1350         }
1351
1352         if (stdin_null_flag) {
1353                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1354                         fatal("open(/dev/null): %s", strerror(errno));
1355                 if (dup2(fd, STDIN_FILENO) == -1)
1356                         fatal("dup2: %s", strerror(errno));
1357                 if (fd > STDERR_FILENO)
1358                         close(fd);
1359         }
1360
1361         term = getenv("TERM");
1362
1363         flags = 0;
1364         if (tty_flag)
1365                 flags |= SSHMUX_FLAG_TTY;
1366         if (subsystem_flag)
1367                 flags |= SSHMUX_FLAG_SUBSYS;
1368         if (options.forward_x11)
1369                 flags |= SSHMUX_FLAG_X11_FWD;
1370         if (options.forward_agent)
1371                 flags |= SSHMUX_FLAG_AGENT_FWD;
1372
1373         buffer_init(&m);
1374
1375         /* Send our command to server */
1376         buffer_put_int(&m, mux_command);
1377         buffer_put_int(&m, flags);
1378         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1379                 fatal("%s: msg_send", __func__);
1380         buffer_clear(&m);
1381
1382         /* Get authorisation status and PID of controlee */
1383         if (ssh_msg_recv(sock, &m) == -1)
1384                 fatal("%s: msg_recv", __func__);
1385         if (buffer_get_char(&m) != SSHMUX_VER)
1386                 fatal("%s: wrong version", __func__);
1387         if (buffer_get_int(&m) != 1)
1388                 fatal("Connection to master denied");
1389         control_server_pid = buffer_get_int(&m);
1390
1391         buffer_clear(&m);
1392
1393         switch (mux_command) {
1394         case SSHMUX_COMMAND_ALIVE_CHECK:
1395                 fprintf(stderr, "Master running (pid=%d)\r\n",
1396                     control_server_pid);
1397                 exit(0);
1398         case SSHMUX_COMMAND_TERMINATE:
1399                 fprintf(stderr, "Exit request sent.\r\n");
1400                 exit(0);
1401         case SSHMUX_COMMAND_OPEN:
1402                 /* continue below */
1403                 break;
1404         default:
1405                 fatal("silly mux_command %d", mux_command);
1406         }
1407
1408         /* SSHMUX_COMMAND_OPEN */
1409         buffer_put_cstring(&m, term ? term : "");
1410         buffer_append(&command, "\0", 1);
1411         buffer_put_cstring(&m, buffer_ptr(&command));
1412
1413         if (options.num_send_env == 0 || environ == NULL) {
1414                 buffer_put_int(&m, 0);
1415         } else {
1416                 /* Pass environment */
1417                 num_env = 0;
1418                 for (i = 0; environ[i] != NULL; i++)
1419                         if (env_permitted(environ[i]))
1420                                 num_env++; /* Count */
1421
1422                 buffer_put_int(&m, num_env);
1423
1424                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1425                         if (env_permitted(environ[i])) {
1426                                 num_env--;
1427                                 buffer_put_cstring(&m, environ[i]);
1428                         }
1429         }
1430
1431         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1432                 fatal("%s: msg_send", __func__);
1433
1434         mm_send_fd(sock, STDIN_FILENO);
1435         mm_send_fd(sock, STDOUT_FILENO);
1436         mm_send_fd(sock, STDERR_FILENO);
1437
1438         /* Wait for reply, so master has a chance to gather ttymodes */
1439         buffer_clear(&m);
1440         if (ssh_msg_recv(sock, &m) == -1)
1441                 fatal("%s: msg_recv", __func__);
1442         if (buffer_get_char(&m) != SSHMUX_VER)
1443                 fatal("%s: wrong version", __func__);
1444         buffer_free(&m);
1445
1446         signal(SIGHUP, control_client_sighandler);
1447         signal(SIGINT, control_client_sighandler);
1448         signal(SIGTERM, control_client_sighandler);
1449         signal(SIGWINCH, control_client_sigrelay);
1450
1451         if (tty_flag)
1452                 enter_raw_mode();
1453
1454         /* Stick around until the controlee closes the client_fd */
1455         exitval = 0;
1456         for (;!control_client_terminate;) {
1457                 r = read(sock, &exitval, sizeof(exitval));
1458                 if (r == 0) {
1459                         debug2("Received EOF from master");
1460                         break;
1461                 }
1462                 if (r > 0)
1463                         debug2("Received exit status from master %d", exitval);
1464                 if (r == -1 && errno != EINTR)
1465                         fatal("%s: read %s", __func__, strerror(errno));
1466         }
1467
1468         if (control_client_terminate)
1469                 debug2("Exiting on signal %d", control_client_terminate);
1470
1471         close(sock);
1472
1473         leave_raw_mode();
1474
1475         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1476                 fprintf(stderr, "Connection to master closed.\r\n");
1477
1478         exit(exitval);
1479 }