ssh.c

   1 /* $OpenBSD: ssh.c,v 1.280 2006/07/08 21:47:12 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 #ifdef HAVE_PATHS_H
  56 #include <paths.h>
  57 #endif
  58 #include <pwd.h>
  59 #include <signal.h>
  60
  61 #include <openssl/evp.h>
  62 #include <openssl/err.h>
  63
  64 #include "ssh.h"
  65 #include "ssh1.h"
  66 #include "ssh2.h"
  67 #include "compat.h"
  68 #include "cipher.h"
  69 #include "xmalloc.h"
  70 #include "packet.h"
  71 #include "buffer.h"
  72 #include "bufaux.h"
  73 #include "channels.h"
  74 #include "key.h"
  75 #include "authfd.h"
  76 #include "authfile.h"
  77 #include "pathnames.h"
  78 #include "dispatch.h"
  79 #include "clientloop.h"
  80 #include "log.h"
  81 #include "readconf.h"
  82 #include "sshconnect.h"
  83 #include "misc.h"
  84 #include "kex.h"
  85 #include "mac.h"
  86 #include "sshpty.h"
  87 #include "match.h"
  88 #include "msg.h"
  89 #include "monitor_fdpass.h"
  90 #include "uidswap.h"
  91 #include "version.h"
  92
  93 #ifdef SMARTCARD
  94 #include "scard.h"
  95 #endif
  96
  97 extern char *__progname;
  98
  99 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
 100 int debug_flag = 0;
 101
 102 /* Flag indicating whether a tty should be allocated */
 103 int tty_flag = 0;
 104 int no_tty_flag = 0;
 105 int force_tty_flag = 0;
 106
 107 /* don't exec a shell */
 108 int no_shell_flag = 0;
 109
 110 /*
 111  * Flag indicating that nothing should be read from stdin.  This can be set
 112  * on the command line.
 113  */
 114 int stdin_null_flag = 0;
 115
 116 /*
 117  * Flag indicating that ssh should fork after authentication.  This is useful
 118  * so that the passphrase can be entered manually, and then ssh goes to the
 119  * background.
 120  */
 121 int fork_after_authentication_flag = 0;
 122
 123 /*
 124  * General data structure for command line options and options configurable
 125  * in configuration files.  See readconf.h.
 126  */
 127 Options options;
 128
 129 /* optional user configfile */
 130 char *config = NULL;
 131
 132 /*
 133  * Name of the host we are connecting to.  This is the name given on the
 134  * command line, or the HostName specified for the user-supplied name in a
 135  * configuration file.
 136  */
 137 char *host;
 138
 139 /* socket address the host resolves to */
 140 struct sockaddr_storage hostaddr;
 141
 142 /* Private host keys. */
 143 Sensitive sensitive_data;
 144
 145 /* Original real UID. */
 146 uid_t original_real_uid;
 147 uid_t original_effective_uid;
 148
 149 /* command to be executed */
 150 Buffer command;
 151
 152 /* Should we execute a command or invoke a subsystem? */
 153 int subsystem_flag = 0;
 154
 155 /* # of replies received for global requests */
 156 static int client_global_request_id = 0;
 157
 158 /* pid of proxycommand child process */
 159 pid_t proxy_command_pid = 0;
 160
 161 /* fd to control socket */
 162 int control_fd = -1;
 163
 164 /* Multiplexing control command */
 165 static u_int mux_command = 0;
 166
 167 /* Only used in control client mode */
 168 volatile sig_atomic_t control_client_terminate = 0;
 169 u_int control_server_pid = 0;
 170
 171 /* Prints a help message to the user.  This function never returns. */
 172
 173 static void
 174 usage(void)
 175 {
 176         fprintf(stderr,
 177 "usage: ssh [-1246AaCfgkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 178 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 179 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 180 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 181 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 182 "           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
 183         );
 184         exit(255);
 185 }
 186
 187 static int ssh_session(void);
 188 static int ssh_session2(void);
 189 static void load_public_identity_files(void);
 190 static void control_client(const char *path);
 191
 192 /*
 193  * Main program for the ssh client.
 194  */
 195 int
 196 main(int ac, char **av)
 197 {
 198         int i, opt, exit_status;
 199         char *p, *cp, *line, buf[256];
 200         struct stat st;
 201         struct passwd *pw;
 202         int dummy;
 203         extern int optind, optreset;
 204         extern char *optarg;
 205         struct servent *sp;
 206         Forward fwd;
 207
 208         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 209         sanitise_stdfd();
 210
 211         __progname = ssh_get_progname(av[0]);
 212         init_rng();
 213
 214         /*
 215          * Save the original real uid.  It will be needed later (uid-swapping
 216          * may clobber the real uid).
 217          */
 218         original_real_uid = getuid();
 219         original_effective_uid = geteuid();
 220
 221         /*
 222          * Use uid-swapping to give up root privileges for the duration of
 223          * option processing.  We will re-instantiate the rights when we are
 224          * ready to create the privileged port, and will permanently drop
 225          * them when the port has been created (actually, when the connection
 226          * has been made, as we may need to create the port several times).
 227          */
 228         PRIV_END;
 229
 230 #ifdef HAVE_SETRLIMIT
 231         /* If we are installed setuid root be careful to not drop core. */
 232         if (original_real_uid != original_effective_uid) {
 233                 struct rlimit rlim;
 234                 rlim.rlim_cur = rlim.rlim_max = 0;
 235                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 236                         fatal("setrlimit failed: %.100s", strerror(errno));
 237         }
 238 #endif
 239         /* Get user data. */
 240         pw = getpwuid(original_real_uid);
 241         if (!pw) {
 242                 logit("You don't exist, go away!");
 243                 exit(255);
 244         }
 245         /* Take a copy of the returned structure. */
 246         pw = pwcopy(pw);
 247
 248         /*
 249          * Set our umask to something reasonable, as some files are created
 250          * with the default umask.  This will make them world-readable but
 251          * writable only by the owner, which is ok for all files for which we
 252          * don't set the modes explicitly.
 253          */
 254         umask(022);
 255
 256         /* Initialize option structure to indicate that no values have been set. */
 257         initialize_options(&options);
 258
 259         /* Parse command-line arguments. */
 260         host = NULL;
 261
 262  again:
 263         while ((opt = getopt(ac, av,
 264             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:MNO:PR:S:TVw:XY")) != -1) {
 265                 switch (opt) {
 266                 case '1':
 267                         options.protocol = SSH_PROTO_1;
 268                         break;
 269                 case '2':
 270                         options.protocol = SSH_PROTO_2;
 271                         break;
 272                 case '4':
 273                         options.address_family = AF_INET;
 274                         break;
 275                 case '6':
 276                         options.address_family = AF_INET6;
 277                         break;
 278                 case 'n':
 279                         stdin_null_flag = 1;
 280                         break;
 281                 case 'f':
 282                         fork_after_authentication_flag = 1;
 283                         stdin_null_flag = 1;
 284                         break;
 285                 case 'x':
 286                         options.forward_x11 = 0;
 287                         break;
 288                 case 'X':
 289                         options.forward_x11 = 1;
 290                         break;
 291                 case 'Y':
 292                         options.forward_x11 = 1;
 293                         options.forward_x11_trusted = 1;
 294                         break;
 295                 case 'g':
 296                         options.gateway_ports = 1;
 297                         break;
 298                 case 'O':
 299                         if (strcmp(optarg, "check") == 0)
 300                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 301                         else if (strcmp(optarg, "exit") == 0)
 302                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 303                         else
 304                                 fatal("Invalid multiplex command.");
 305                         break;
 306                 case 'P':       /* deprecated */
 307                         options.use_privileged_port = 0;
 308                         break;
 309                 case 'a':
 310                         options.forward_agent = 0;
 311                         break;
 312                 case 'A':
 313                         options.forward_agent = 1;
 314                         break;
 315                 case 'k':
 316                         options.gss_deleg_creds = 0;
 317                         break;
 318                 case 'i':
 319                         if (stat(optarg, &st) < 0) {
 320                                 fprintf(stderr, "Warning: Identity file %s "
 321                                     "not accessible: %s.\n", optarg,
 322                                     strerror(errno));
 323                                 break;
 324                         }
 325                         if (options.num_identity_files >=
 326                             SSH_MAX_IDENTITY_FILES)
 327                                 fatal("Too many identity files specified "
 328                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 329                         options.identity_files[options.num_identity_files++] =
 330                             xstrdup(optarg);
 331                         break;
 332                 case 'I':
 333 #ifdef SMARTCARD
 334                         options.smartcard_device = xstrdup(optarg);
 335 #else
 336                         fprintf(stderr, "no support for smartcards.\n");
 337 #endif
 338                         break;
 339                 case 't':
 340                         if (tty_flag)
 341                                 force_tty_flag = 1;
 342                         tty_flag = 1;
 343                         break;
 344                 case 'v':
 345                         if (debug_flag == 0) {
 346                                 debug_flag = 1;
 347                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 348                         } else {
 349                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 350                                         options.log_level++;
 351                                 break;
 352                         }
 353                         /* FALLTHROUGH */
 354                 case 'V':
 355                         fprintf(stderr, "%s, %s\n",
 356                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 357                         if (opt == 'V')
 358                                 exit(0);
 359                         break;
 360                 case 'w':
 361                         if (options.tun_open == -1)
 362                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 363                         options.tun_local = a2tun(optarg, &options.tun_remote);
 364                         if (options.tun_local == SSH_TUNID_ERR) {
 365                                 fprintf(stderr, "Bad tun device '%s'\n", optarg);
 366                                 exit(255);
 367                         }
 368                         break;
 369                 case 'q':
 370                         options.log_level = SYSLOG_LEVEL_QUIET;
 371                         break;
 372                 case 'e':
 373                         if (optarg[0] == '^' && optarg[2] == 0 &&
 374                             (u_char) optarg[1] >= 64 &&
 375                             (u_char) optarg[1] < 128)
 376                                 options.escape_char = (u_char) optarg[1] & 31;
 377                         else if (strlen(optarg) == 1)
 378                                 options.escape_char = (u_char) optarg[0];
 379                         else if (strcmp(optarg, "none") == 0)
 380                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 381                         else {
 382                                 fprintf(stderr, "Bad escape character '%s'.\n",
 383                                     optarg);
 384                                 exit(255);
 385                         }
 386                         break;
 387                 case 'c':
 388                         if (ciphers_valid(optarg)) {
 389                                 /* SSH2 only */
 390                                 options.ciphers = xstrdup(optarg);
 391                                 options.cipher = SSH_CIPHER_INVALID;
 392                         } else {
 393                                 /* SSH1 only */
 394                                 options.cipher = cipher_number(optarg);
 395                                 if (options.cipher == -1) {
 396                                         fprintf(stderr,
 397                                             "Unknown cipher type '%s'\n",
 398                                             optarg);
 399                                         exit(255);
 400                                 }
 401                                 if (options.cipher == SSH_CIPHER_3DES)
 402                                         options.ciphers = "3des-cbc";
 403                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 404                                         options.ciphers = "blowfish-cbc";
 405                                 else
 406                                         options.ciphers = (char *)-1;
 407                         }
 408                         break;
 409                 case 'm':
 410                         if (mac_valid(optarg))
 411                                 options.macs = xstrdup(optarg);
 412                         else {
 413                                 fprintf(stderr, "Unknown mac type '%s'\n",
 414                                     optarg);
 415                                 exit(255);
 416                         }
 417                         break;
 418                 case 'M':
 419                         if (options.control_master == SSHCTL_MASTER_YES)
 420                                 options.control_master = SSHCTL_MASTER_ASK;
 421                         else
 422                                 options.control_master = SSHCTL_MASTER_YES;
 423                         break;
 424                 case 'p':
 425                         options.port = a2port(optarg);
 426                         if (options.port == 0) {
 427                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 428                                 exit(255);
 429                         }
 430                         break;
 431                 case 'l':
 432                         options.user = optarg;
 433                         break;
 434
 435                 case 'L':
 436                         if (parse_forward(&fwd, optarg))
 437                                 add_local_forward(&options, &fwd);
 438                         else {
 439                                 fprintf(stderr,
 440                                     "Bad local forwarding specification '%s'\n",
 441                                     optarg);
 442                                 exit(255);
 443                         }
 444                         break;
 445
 446                 case 'R':
 447                         if (parse_forward(&fwd, optarg)) {
 448                                 add_remote_forward(&options, &fwd);
 449                         } else {
 450                                 fprintf(stderr,
 451                                     "Bad remote forwarding specification "
 452                                     "'%s'\n", optarg);
 453                                 exit(255);
 454                         }
 455                         break;
 456
 457                 case 'D':
 458                         cp = p = xstrdup(optarg);
 459                         memset(&fwd, '\0', sizeof(fwd));
 460                         fwd.connect_host = "socks";
 461                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 462                                 fprintf(stderr, "Bad dynamic forwarding "
 463                                     "specification '%.100s'\n", optarg);
 464                                 exit(255);
 465                         }
 466                         if (cp != NULL) {
 467                                 fwd.listen_port = a2port(cp);
 468                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 469                         } else {
 470                                 fwd.listen_port = a2port(fwd.listen_host);
 471                                 fwd.listen_host = NULL;
 472                         }
 473
 474                         if (fwd.listen_port == 0) {
 475                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 476                                     optarg);
 477                                 exit(255);
 478                         }
 479                         add_local_forward(&options, &fwd);
 480                         xfree(p);
 481                         break;
 482
 483                 case 'C':
 484                         options.compression = 1;
 485                         break;
 486                 case 'N':
 487                         no_shell_flag = 1;
 488                         no_tty_flag = 1;
 489                         break;
 490                 case 'T':
 491                         no_tty_flag = 1;
 492                         break;
 493                 case 'o':
 494                         dummy = 1;
 495                         line = xstrdup(optarg);
 496                         if (process_config_line(&options, host ? host : "",
 497                             line, "command-line", 0, &dummy) != 0)
 498                                 exit(255);
 499                         xfree(line);
 500                         break;
 501                 case 's':
 502                         subsystem_flag = 1;
 503                         break;
 504                 case 'S':
 505                         if (options.control_path != NULL)
 506                                 free(options.control_path);
 507                         options.control_path = xstrdup(optarg);
 508                         break;
 509                 case 'b':
 510                         options.bind_address = optarg;
 511                         break;
 512                 case 'F':
 513                         config = optarg;
 514                         break;
 515                 default:
 516                         usage();
 517                 }
 518         }
 519
 520         ac -= optind;
 521         av += optind;
 522
 523         if (ac > 0 && !host && **av != '-') {
 524                 if (strrchr(*av, '@')) {
 525                         p = xstrdup(*av);
 526                         cp = strrchr(p, '@');
 527                         if (cp == NULL || cp == p)
 528                                 usage();
 529                         options.user = p;
 530                         *cp = '\0';
 531                         host = ++cp;
 532                 } else
 533                         host = *av;
 534                 if (ac > 1) {
 535                         optind = optreset = 1;
 536                         goto again;
 537                 }
 538                 ac--, av++;
 539         }
 540
 541         /* Check that we got a host name. */
 542         if (!host)
 543                 usage();
 544
 545         SSLeay_add_all_algorithms();
 546         ERR_load_crypto_strings();
 547
 548         /* Initialize the command to execute on remote host. */
 549         buffer_init(&command);
 550
 551         /*
 552          * Save the command to execute on the remote host in a buffer. There
 553          * is no limit on the length of the command, except by the maximum
 554          * packet size.  Also sets the tty flag if there is no command.
 555          */
 556         if (!ac) {
 557                 /* No command specified - execute shell on a tty. */
 558                 tty_flag = 1;
 559                 if (subsystem_flag) {
 560                         fprintf(stderr,
 561                             "You must specify a subsystem to invoke.\n");
 562                         usage();
 563                 }
 564         } else {
 565                 /* A command has been specified.  Store it into the buffer. */
 566                 for (i = 0; i < ac; i++) {
 567                         if (i)
 568                                 buffer_append(&command, " ", 1);
 569                         buffer_append(&command, av[i], strlen(av[i]));
 570                 }
 571         }
 572
 573         /* Cannot fork to background if no command. */
 574         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 575                 fatal("Cannot fork into background without a command to execute.");
 576
 577         /* Allocate a tty by default if no command specified. */
 578         if (buffer_len(&command) == 0)
 579                 tty_flag = 1;
 580
 581         /* Force no tty */
 582         if (no_tty_flag)
 583                 tty_flag = 0;
 584         /* Do not allocate a tty if stdin is not a tty. */
 585         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 586                 if (tty_flag)
 587                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 588                 tty_flag = 0;
 589         }
 590
 591         /*
 592          * Initialize "log" output.  Since we are the client all output
 593          * actually goes to stderr.
 594          */
 595         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 596             SYSLOG_FACILITY_USER, 1);
 597
 598         /*
 599          * Read per-user configuration file.  Ignore the system wide config
 600          * file if the user specifies a config file on the command line.
 601          */
 602         if (config != NULL) {
 603                 if (!read_config_file(config, host, &options, 0))
 604                         fatal("Can't open user config file %.100s: "
 605                             "%.100s", config, strerror(errno));
 606         } else  {
 607                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 608                     _PATH_SSH_USER_CONFFILE);
 609                 (void)read_config_file(buf, host, &options, 1);
 610
 611                 /* Read systemwide configuration file after use config. */
 612                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 613                     &options, 0);
 614         }
 615
 616         /* Fill configuration defaults. */
 617         fill_default_options(&options);
 618
 619         channel_set_af(options.address_family);
 620
 621         /* reinit */
 622         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 623
 624         seed_rng();
 625
 626         if (options.user == NULL)
 627                 options.user = xstrdup(pw->pw_name);
 628
 629         if (options.hostname != NULL)
 630                 host = options.hostname;
 631
 632         /* force lowercase for hostkey matching */
 633         if (options.host_key_alias != NULL) {
 634                 for (p = options.host_key_alias; *p; p++)
 635                         if (isupper(*p))
 636                                 *p = (char)tolower(*p);
 637         }
 638
 639         /* Get default port if port has not been set. */
 640         if (options.port == 0) {
 641                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 642                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 643         }
 644
 645         if (options.proxy_command != NULL &&
 646             strcmp(options.proxy_command, "none") == 0)
 647                 options.proxy_command = NULL;
 648         if (options.control_path != NULL &&
 649             strcmp(options.control_path, "none") == 0)
 650                 options.control_path = NULL;
 651
 652         if (options.control_path != NULL) {
 653                 char thishost[NI_MAXHOST];
 654
 655                 if (gethostname(thishost, sizeof(thishost)) == -1)
 656                         fatal("gethostname: %s", strerror(errno));
 657                 snprintf(buf, sizeof(buf), "%d", options.port);
 658                 cp = tilde_expand_filename(options.control_path,
 659                     original_real_uid);
 660                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 661                     "r", options.user, "l", thishost, (char *)NULL);
 662                 xfree(cp);
 663         }
 664         if (mux_command != 0 && options.control_path == NULL)
 665                 fatal("No ControlPath specified for \"-O\" command");
 666         if (options.control_path != NULL)
 667                 control_client(options.control_path);
 668
 669         /* Open a connection to the remote host. */
 670         if (ssh_connect(host, &hostaddr, options.port,
 671             options.address_family, options.connection_attempts,
 672 #ifdef HAVE_CYGWIN
 673             options.use_privileged_port,
 674 #else
 675             original_effective_uid == 0 && options.use_privileged_port,
 676 #endif
 677             options.proxy_command) != 0)
 678                 exit(255);
 679
 680         /*
 681          * If we successfully made the connection, load the host private key
 682          * in case we will need it later for combined rsa-rhosts
 683          * authentication. This must be done before releasing extra
 684          * privileges, because the file is only readable by root.
 685          * If we cannot access the private keys, load the public keys
 686          * instead and try to execute the ssh-keysign helper instead.
 687          */
 688         sensitive_data.nkeys = 0;
 689         sensitive_data.keys = NULL;
 690         sensitive_data.external_keysign = 0;
 691         if (options.rhosts_rsa_authentication ||
 692             options.hostbased_authentication) {
 693                 sensitive_data.nkeys = 3;
 694                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 695                     sizeof(Key));
 696
 697                 PRIV_START;
 698                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 699                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 700                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 701                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 702                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 703                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 704                 PRIV_END;
 705
 706                 if (options.hostbased_authentication == 1 &&
 707                     sensitive_data.keys[0] == NULL &&
 708                     sensitive_data.keys[1] == NULL &&
 709                     sensitive_data.keys[2] == NULL) {
 710                         sensitive_data.keys[1] = key_load_public(
 711                             _PATH_HOST_DSA_KEY_FILE, NULL);
 712                         sensitive_data.keys[2] = key_load_public(
 713                             _PATH_HOST_RSA_KEY_FILE, NULL);
 714                         sensitive_data.external_keysign = 1;
 715                 }
 716         }
 717         /*
 718          * Get rid of any extra privileges that we may have.  We will no
 719          * longer need them.  Also, extra privileges could make it very hard
 720          * to read identity files and other non-world-readable files from the
 721          * user's home directory if it happens to be on a NFS volume where
 722          * root is mapped to nobody.
 723          */
 724         if (original_effective_uid == 0) {
 725                 PRIV_START;
 726                 permanently_set_uid(pw);
 727         }
 728
 729         /*
 730          * Now that we are back to our own permissions, create ~/.ssh
 731          * directory if it doesn't already exist.
 732          */
 733         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 734         if (stat(buf, &st) < 0)
 735                 if (mkdir(buf, 0700) < 0)
 736                         error("Could not create directory '%.200s'.", buf);
 737
 738         /* load options.identity_files */
 739         load_public_identity_files();
 740
 741         /* Expand ~ in known host file names. */
 742         /* XXX mem-leaks: */
 743         options.system_hostfile =
 744             tilde_expand_filename(options.system_hostfile, original_real_uid);
 745         options.user_hostfile =
 746             tilde_expand_filename(options.user_hostfile, original_real_uid);
 747         options.system_hostfile2 =
 748             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 749         options.user_hostfile2 =
 750             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 751
 752         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 753
 754         /* Log into the remote system.  This never returns if the login fails. */
 755         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 756
 757         /* We no longer need the private host keys.  Clear them now. */
 758         if (sensitive_data.nkeys != 0) {
 759                 for (i = 0; i < sensitive_data.nkeys; i++) {
 760                         if (sensitive_data.keys[i] != NULL) {
 761                                 /* Destroys contents safely */
 762                                 debug3("clear hostkey %d", i);
 763                                 key_free(sensitive_data.keys[i]);
 764                                 sensitive_data.keys[i] = NULL;
 765                         }
 766                 }
 767                 xfree(sensitive_data.keys);
 768         }
 769         for (i = 0; i < options.num_identity_files; i++) {
 770                 if (options.identity_files[i]) {
 771                         xfree(options.identity_files[i]);
 772                         options.identity_files[i] = NULL;
 773                 }
 774                 if (options.identity_keys[i]) {
 775                         key_free(options.identity_keys[i]);
 776                         options.identity_keys[i] = NULL;
 777                 }
 778         }
 779
 780         exit_status = compat20 ? ssh_session2() : ssh_session();
 781         packet_close();
 782
 783         if (options.control_path != NULL && control_fd != -1)
 784                 unlink(options.control_path);
 785
 786         /*
 787          * Send SIGHUP to proxy command if used. We don't wait() in
 788          * case it hangs and instead rely on init to reap the child
 789          */
 790         if (proxy_command_pid > 1)
 791                 kill(proxy_command_pid, SIGHUP);
 792
 793         return exit_status;
 794 }
 795
 796 static void
 797 ssh_init_forwarding(void)
 798 {
 799         int success = 0;
 800         int i;
 801
 802         /* Initiate local TCP/IP port forwardings. */
 803         for (i = 0; i < options.num_local_forwards; i++) {
 804                 debug("Local connections to %.200s:%d forwarded to remote "
 805                     "address %.200s:%d",
 806                     (options.local_forwards[i].listen_host == NULL) ?
 807                     (options.gateway_ports ? "*" : "LOCALHOST") :
 808                     options.local_forwards[i].listen_host,
 809                     options.local_forwards[i].listen_port,
 810                     options.local_forwards[i].connect_host,
 811                     options.local_forwards[i].connect_port);
 812                 success += channel_setup_local_fwd_listener(
 813                     options.local_forwards[i].listen_host,
 814                     options.local_forwards[i].listen_port,
 815                     options.local_forwards[i].connect_host,
 816                     options.local_forwards[i].connect_port,
 817                     options.gateway_ports);
 818         }
 819         if (i > 0 && success == 0)
 820                 error("Could not request local forwarding.");
 821
 822         /* Initiate remote TCP/IP port forwardings. */
 823         for (i = 0; i < options.num_remote_forwards; i++) {
 824                 debug("Remote connections from %.200s:%d forwarded to "
 825                     "local address %.200s:%d",
 826                     (options.remote_forwards[i].listen_host == NULL) ?
 827                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 828                     options.remote_forwards[i].listen_port,
 829                     options.remote_forwards[i].connect_host,
 830                     options.remote_forwards[i].connect_port);
 831                 channel_request_remote_forwarding(
 832                     options.remote_forwards[i].listen_host,
 833                     options.remote_forwards[i].listen_port,
 834                     options.remote_forwards[i].connect_host,
 835                     options.remote_forwards[i].connect_port);
 836         }
 837 }
 838
 839 static void
 840 check_agent_present(void)
 841 {
 842         if (options.forward_agent) {
 843                 /* Clear agent forwarding if we don't have an agent. */
 844                 if (!ssh_agent_present())
 845                         options.forward_agent = 0;
 846         }
 847 }
 848
 849 static int
 850 ssh_session(void)
 851 {
 852         int type;
 853         int interactive = 0;
 854         int have_tty = 0;
 855         struct winsize ws;
 856         char *cp;
 857         const char *display;
 858
 859         /* Enable compression if requested. */
 860         if (options.compression) {
 861                 debug("Requesting compression at level %d.", options.compression_level);
 862
 863                 if (options.compression_level < 1 || options.compression_level > 9)
 864                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 865
 866                 /* Send the request. */
 867                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 868                 packet_put_int(options.compression_level);
 869                 packet_send();
 870                 packet_write_wait();
 871                 type = packet_read();
 872                 if (type == SSH_SMSG_SUCCESS)
 873                         packet_start_compression(options.compression_level);
 874                 else if (type == SSH_SMSG_FAILURE)
 875                         logit("Warning: Remote host refused compression.");
 876                 else
 877                         packet_disconnect("Protocol error waiting for compression response.");
 878         }
 879         /* Allocate a pseudo tty if appropriate. */
 880         if (tty_flag) {
 881                 debug("Requesting pty.");
 882
 883                 /* Start the packet. */
 884                 packet_start(SSH_CMSG_REQUEST_PTY);
 885
 886                 /* Store TERM in the packet.  There is no limit on the
 887                    length of the string. */
 888                 cp = getenv("TERM");
 889                 if (!cp)
 890                         cp = "";
 891                 packet_put_cstring(cp);
 892
 893                 /* Store window size in the packet. */
 894                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 895                         memset(&ws, 0, sizeof(ws));
 896                 packet_put_int((u_int)ws.ws_row);
 897                 packet_put_int((u_int)ws.ws_col);
 898                 packet_put_int((u_int)ws.ws_xpixel);
 899                 packet_put_int((u_int)ws.ws_ypixel);
 900
 901                 /* Store tty modes in the packet. */
 902                 tty_make_modes(fileno(stdin), NULL);
 903
 904                 /* Send the packet, and wait for it to leave. */
 905                 packet_send();
 906                 packet_write_wait();
 907
 908                 /* Read response from the server. */
 909                 type = packet_read();
 910                 if (type == SSH_SMSG_SUCCESS) {
 911                         interactive = 1;
 912                         have_tty = 1;
 913                 } else if (type == SSH_SMSG_FAILURE)
 914                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 915                 else
 916                         packet_disconnect("Protocol error waiting for pty request response.");
 917         }
 918         /* Request X11 forwarding if enabled and DISPLAY is set. */
 919         display = getenv("DISPLAY");
 920         if (options.forward_x11 && display != NULL) {
 921                 char *proto, *data;
 922                 /* Get reasonable local authentication information. */
 923                 client_x11_get_proto(display, options.xauth_location,
 924                     options.forward_x11_trusted, &proto, &data);
 925                 /* Request forwarding with authentication spoofing. */
 926                 debug("Requesting X11 forwarding with authentication spoofing.");
 927                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 928
 929                 /* Read response from the server. */
 930                 type = packet_read();
 931                 if (type == SSH_SMSG_SUCCESS) {
 932                         interactive = 1;
 933                 } else if (type == SSH_SMSG_FAILURE) {
 934                         logit("Warning: Remote host denied X11 forwarding.");
 935                 } else {
 936                         packet_disconnect("Protocol error waiting for X11 forwarding");
 937                 }
 938         }
 939         /* Tell the packet module whether this is an interactive session. */
 940         packet_set_interactive(interactive);
 941
 942         /* Request authentication agent forwarding if appropriate. */
 943         check_agent_present();
 944
 945         if (options.forward_agent) {
 946                 debug("Requesting authentication agent forwarding.");
 947                 auth_request_forwarding();
 948
 949                 /* Read response from the server. */
 950                 type = packet_read();
 951                 packet_check_eom();
 952                 if (type != SSH_SMSG_SUCCESS)
 953                         logit("Warning: Remote host denied authentication agent forwarding.");
 954         }
 955
 956         /* Initiate port forwardings. */
 957         ssh_init_forwarding();
 958
 959         /* If requested, let ssh continue in the background. */
 960         if (fork_after_authentication_flag)
 961                 if (daemon(1, 1) < 0)
 962                         fatal("daemon() failed: %.200s", strerror(errno));
 963
 964         /*
 965          * If a command was specified on the command line, execute the
 966          * command now. Otherwise request the server to start a shell.
 967          */
 968         if (buffer_len(&command) > 0) {
 969                 int len = buffer_len(&command);
 970                 if (len > 900)
 971                         len = 900;
 972                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 973                 packet_start(SSH_CMSG_EXEC_CMD);
 974                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 975                 packet_send();
 976                 packet_write_wait();
 977         } else {
 978                 debug("Requesting shell.");
 979                 packet_start(SSH_CMSG_EXEC_SHELL);
 980                 packet_send();
 981                 packet_write_wait();
 982         }
 983
 984         /* Enter the interactive session. */
 985         return client_loop(have_tty, tty_flag ?
 986             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
 987 }
 988
 989 static void
 990 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
 991 {
 992         int id, len;
 993
 994         id = packet_get_int();
 995         len = buffer_len(&command);
 996         if (len > 900)
 997                 len = 900;
 998         packet_check_eom();
 999         if (type == SSH2_MSG_CHANNEL_FAILURE)
1000                 fatal("Request for subsystem '%.*s' failed on channel %d",
1001                     len, (u_char *)buffer_ptr(&command), id);
1002 }
1003
1004 void
1005 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1006 {
1007         int i;
1008
1009         i = client_global_request_id++;
1010         if (i >= options.num_remote_forwards)
1011                 return;
1012         debug("remote forward %s for: listen %d, connect %s:%d",
1013             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1014             options.remote_forwards[i].listen_port,
1015             options.remote_forwards[i].connect_host,
1016             options.remote_forwards[i].connect_port);
1017         if (type == SSH2_MSG_REQUEST_FAILURE)
1018                 logit("Warning: remote port forwarding failed for listen "
1019                     "port %d", options.remote_forwards[i].listen_port);
1020 }
1021
1022 static void
1023 ssh_control_listener(void)
1024 {
1025         struct sockaddr_un addr;
1026         mode_t old_umask;
1027         int addr_len;
1028
1029         if (options.control_path == NULL ||
1030             options.control_master == SSHCTL_MASTER_NO)
1031                 return;
1032
1033         debug("setting up multiplex master socket");
1034
1035         memset(&addr, '\0', sizeof(addr));
1036         addr.sun_family = AF_UNIX;
1037         addr_len = offsetof(struct sockaddr_un, sun_path) +
1038             strlen(options.control_path) + 1;
1039
1040         if (strlcpy(addr.sun_path, options.control_path,
1041             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1042                 fatal("ControlPath too long");
1043
1044         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1045                 fatal("%s socket(): %s", __func__, strerror(errno));
1046
1047         old_umask = umask(0177);
1048         if (bind(control_fd, (struct sockaddr *)&addr, addr_len) == -1) {
1049                 control_fd = -1;
1050                 if (errno == EINVAL || errno == EADDRINUSE)
1051                         fatal("ControlSocket %s already exists",
1052                             options.control_path);
1053                 else
1054                         fatal("%s bind(): %s", __func__, strerror(errno));
1055         }
1056         umask(old_umask);
1057
1058         if (listen(control_fd, 64) == -1)
1059                 fatal("%s listen(): %s", __func__, strerror(errno));
1060
1061         set_nonblock(control_fd);
1062 }
1063
1064 /* request pty/x11/agent/tcpfwd/shell for channel */
1065 static void
1066 ssh_session2_setup(int id, void *arg)
1067 {
1068         extern char **environ;
1069         const char *display;
1070         int interactive = tty_flag;
1071
1072         display = getenv("DISPLAY");
1073         if (options.forward_x11 && display != NULL) {
1074                 char *proto, *data;
1075                 /* Get reasonable local authentication information. */
1076                 client_x11_get_proto(display, options.xauth_location,
1077                     options.forward_x11_trusted, &proto, &data);
1078                 /* Request forwarding with authentication spoofing. */
1079                 debug("Requesting X11 forwarding with authentication spoofing.");
1080                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1081                 interactive = 1;
1082                 /* XXX wait for reply */
1083         }
1084
1085         check_agent_present();
1086         if (options.forward_agent) {
1087                 debug("Requesting authentication agent forwarding.");
1088                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1089                 packet_send();
1090         }
1091
1092         if (options.tun_open != SSH_TUNMODE_NO) {
1093                 Channel *c;
1094                 int fd;
1095
1096                 debug("Requesting tun.");
1097                 if ((fd = tun_open(options.tun_local,
1098                     options.tun_open)) >= 0) {
1099                         c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1100                             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1101                             0, "tun", 1);
1102                         c->datagram = 1;
1103 #if defined(SSH_TUN_FILTER)
1104                         if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
1105                                 channel_register_filter(c->self, sys_tun_infilter,
1106                                     sys_tun_outfilter);
1107 #endif
1108                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1109                         packet_put_cstring("tun@openssh.com");
1110                         packet_put_int(c->self);
1111                         packet_put_int(c->local_window_max);
1112                         packet_put_int(c->local_maxpacket);
1113                         packet_put_int(options.tun_open);
1114                         packet_put_int(options.tun_remote);
1115                         packet_send();
1116                 }
1117         }
1118
1119         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1120             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1121
1122         packet_set_interactive(interactive);
1123 }
1124
1125 /* open new channel for a session */
1126 static int
1127 ssh_session2_open(void)
1128 {
1129         Channel *c;
1130         int window, packetmax, in, out, err;
1131
1132         if (stdin_null_flag) {
1133                 in = open(_PATH_DEVNULL, O_RDONLY);
1134         } else {
1135                 in = dup(STDIN_FILENO);
1136         }
1137         out = dup(STDOUT_FILENO);
1138         err = dup(STDERR_FILENO);
1139
1140         if (in < 0 || out < 0 || err < 0)
1141                 fatal("dup() in/out/err failed");
1142
1143         /* enable nonblocking unless tty */
1144         if (!isatty(in))
1145                 set_nonblock(in);
1146         if (!isatty(out))
1147                 set_nonblock(out);
1148         if (!isatty(err))
1149                 set_nonblock(err);
1150
1151         window = CHAN_SES_WINDOW_DEFAULT;
1152         packetmax = CHAN_SES_PACKET_DEFAULT;
1153         if (tty_flag) {
1154                 window >>= 1;
1155                 packetmax >>= 1;
1156         }
1157         c = channel_new(
1158             "session", SSH_CHANNEL_OPENING, in, out, err,
1159             window, packetmax, CHAN_EXTENDED_WRITE,
1160             "client-session", /*nonblock*/0);
1161
1162         debug3("ssh_session2_open: channel_new: %d", c->self);
1163
1164         channel_send_open(c->self);
1165         if (!no_shell_flag)
1166                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1167
1168         return c->self;
1169 }
1170
1171 static int
1172 ssh_session2(void)
1173 {
1174         int id = -1;
1175
1176         /* XXX should be pre-session */
1177         ssh_init_forwarding();
1178         ssh_control_listener();
1179
1180         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1181                 id = ssh_session2_open();
1182
1183         /* Execute a local command */
1184         if (options.local_command != NULL &&
1185             options.permit_local_command)
1186                 ssh_local_cmd(options.local_command);
1187
1188         /* If requested, let ssh continue in the background. */
1189         if (fork_after_authentication_flag)
1190                 if (daemon(1, 1) < 0)
1191                         fatal("daemon() failed: %.200s", strerror(errno));
1192
1193         return client_loop(tty_flag, tty_flag ?
1194             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1195 }
1196
1197 static void
1198 load_public_identity_files(void)
1199 {
1200         char *filename, *cp, thishost[NI_MAXHOST];
1201         int i = 0;
1202         Key *public;
1203         struct passwd *pw;
1204 #ifdef SMARTCARD
1205         Key **keys;
1206
1207         if (options.smartcard_device != NULL &&
1208             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1209             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1210                 int count = 0;
1211                 for (i = 0; keys[i] != NULL; i++) {
1212                         count++;
1213                         memmove(&options.identity_files[1], &options.identity_files[0],
1214                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1215                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1216                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1217                         options.num_identity_files++;
1218                         options.identity_keys[0] = keys[i];
1219                         options.identity_files[0] = sc_get_key_label(keys[i]);
1220                 }
1221                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1222                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1223                 i = count;
1224                 xfree(keys);
1225         }
1226 #endif /* SMARTCARD */
1227         if ((pw = getpwuid(original_real_uid)) == NULL)
1228                 fatal("load_public_identity_files: getpwuid failed");
1229         if (gethostname(thishost, sizeof(thishost)) == -1)
1230                 fatal("load_public_identity_files: gethostname: %s",
1231                     strerror(errno));
1232         for (; i < options.num_identity_files; i++) {
1233                 cp = tilde_expand_filename(options.identity_files[i],
1234                     original_real_uid);
1235                 filename = percent_expand(cp, "d", pw->pw_dir,
1236                     "u", pw->pw_name, "l", thishost, "h", host,
1237                     "r", options.user, (char *)NULL);
1238                 xfree(cp);
1239                 public = key_load_public(filename, NULL);
1240                 debug("identity file %s type %d", filename,
1241                     public ? public->type : -1);
1242                 xfree(options.identity_files[i]);
1243                 options.identity_files[i] = filename;
1244                 options.identity_keys[i] = public;
1245         }
1246 }
1247
1248 static void
1249 control_client_sighandler(int signo)
1250 {
1251         control_client_terminate = signo;
1252 }
1253
1254 static void
1255 control_client_sigrelay(int signo)
1256 {
1257         if (control_server_pid > 1)
1258                 kill(control_server_pid, signo);
1259 }
1260
1261 static int
1262 env_permitted(char *env)
1263 {
1264         int i;
1265         char name[1024], *cp;
1266
1267         if (strlcpy(name, env, sizeof(name)) >= sizeof(name))
1268                 fatal("env_permitted: name too long");
1269         if ((cp = strchr(name, '=')) == NULL)
1270                 return (0);
1271
1272         *cp = '\0';
1273
1274         for (i = 0; i < options.num_send_env; i++)
1275                 if (match_pattern(name, options.send_env[i]))
1276                         return (1);
1277
1278         return (0);
1279 }
1280
1281 static void
1282 control_client(const char *path)
1283 {
1284         struct sockaddr_un addr;
1285         int i, r, fd, sock, exitval, num_env, addr_len;
1286         Buffer m;
1287         char *term;
1288         extern char **environ;
1289         u_int  flags;
1290
1291         if (mux_command == 0)
1292                 mux_command = SSHMUX_COMMAND_OPEN;
1293
1294         switch (options.control_master) {
1295         case SSHCTL_MASTER_AUTO:
1296         case SSHCTL_MASTER_AUTO_ASK:
1297                 debug("auto-mux: Trying existing master");
1298                 /* FALLTHROUGH */
1299         case SSHCTL_MASTER_NO:
1300                 break;
1301         default:
1302                 return;
1303         }
1304
1305         memset(&addr, '\0', sizeof(addr));
1306         addr.sun_family = AF_UNIX;
1307         addr_len = offsetof(struct sockaddr_un, sun_path) +
1308             strlen(path) + 1;
1309
1310         if (strlcpy(addr.sun_path, path,
1311             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1312                 fatal("ControlPath too long");
1313
1314         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1315                 fatal("%s socket(): %s", __func__, strerror(errno));
1316
1317         if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) {
1318                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1319                         fatal("Control socket connect(%.100s): %s", path,
1320                             strerror(errno));
1321                 }
1322                 if (errno == ENOENT)
1323                         debug("Control socket \"%.100s\" does not exist", path);
1324                 else {
1325                         error("Control socket connect(%.100s): %s", path,
1326                             strerror(errno));
1327                 }
1328                 close(sock);
1329                 return;
1330         }
1331
1332         if (stdin_null_flag) {
1333                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1334                         fatal("open(/dev/null): %s", strerror(errno));
1335                 if (dup2(fd, STDIN_FILENO) == -1)
1336                         fatal("dup2: %s", strerror(errno));
1337                 if (fd > STDERR_FILENO)
1338                         close(fd);
1339         }
1340
1341         term = getenv("TERM");
1342
1343         flags = 0;
1344         if (tty_flag)
1345                 flags |= SSHMUX_FLAG_TTY;
1346         if (subsystem_flag)
1347                 flags |= SSHMUX_FLAG_SUBSYS;
1348         if (options.forward_x11)
1349                 flags |= SSHMUX_FLAG_X11_FWD;
1350         if (options.forward_agent)
1351                 flags |= SSHMUX_FLAG_AGENT_FWD;
1352
1353         buffer_init(&m);
1354
1355         /* Send our command to server */
1356         buffer_put_int(&m, mux_command);
1357         buffer_put_int(&m, flags);
1358         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1359                 fatal("%s: msg_send", __func__);
1360         buffer_clear(&m);
1361
1362         /* Get authorisation status and PID of controlee */
1363         if (ssh_msg_recv(sock, &m) == -1)
1364                 fatal("%s: msg_recv", __func__);
1365         if (buffer_get_char(&m) != SSHMUX_VER)
1366                 fatal("%s: wrong version", __func__);
1367         if (buffer_get_int(&m) != 1)
1368                 fatal("Connection to master denied");
1369         control_server_pid = buffer_get_int(&m);
1370
1371         buffer_clear(&m);
1372
1373         switch (mux_command) {
1374         case SSHMUX_COMMAND_ALIVE_CHECK:
1375                 fprintf(stderr, "Master running (pid=%d)\r\n",
1376                     control_server_pid);
1377                 exit(0);
1378         case SSHMUX_COMMAND_TERMINATE:
1379                 fprintf(stderr, "Exit request sent.\r\n");
1380                 exit(0);
1381         case SSHMUX_COMMAND_OPEN:
1382                 /* continue below */
1383                 break;
1384         default:
1385                 fatal("silly mux_command %d", mux_command);
1386         }
1387
1388         /* SSHMUX_COMMAND_OPEN */
1389         buffer_put_cstring(&m, term ? term : "");
1390         buffer_append(&command, "\0", 1);
1391         buffer_put_cstring(&m, buffer_ptr(&command));
1392
1393         if (options.num_send_env == 0 || environ == NULL) {
1394                 buffer_put_int(&m, 0);
1395         } else {
1396                 /* Pass environment */
1397                 num_env = 0;
1398                 for (i = 0; environ[i] != NULL; i++)
1399                         if (env_permitted(environ[i]))
1400                                 num_env++; /* Count */
1401
1402                 buffer_put_int(&m, num_env);
1403
1404                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1405                         if (env_permitted(environ[i])) {
1406                                 num_env--;
1407                                 buffer_put_cstring(&m, environ[i]);
1408                         }
1409         }
1410
1411         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1412                 fatal("%s: msg_send", __func__);
1413
1414         mm_send_fd(sock, STDIN_FILENO);
1415         mm_send_fd(sock, STDOUT_FILENO);
1416         mm_send_fd(sock, STDERR_FILENO);
1417
1418         /* Wait for reply, so master has a chance to gather ttymodes */
1419         buffer_clear(&m);
1420         if (ssh_msg_recv(sock, &m) == -1)
1421                 fatal("%s: msg_recv", __func__);
1422         if (buffer_get_char(&m) != SSHMUX_VER)
1423                 fatal("%s: wrong version", __func__);
1424         buffer_free(&m);
1425
1426         signal(SIGHUP, control_client_sighandler);
1427         signal(SIGINT, control_client_sighandler);
1428         signal(SIGTERM, control_client_sighandler);
1429         signal(SIGWINCH, control_client_sigrelay);
1430
1431         if (tty_flag)
1432                 enter_raw_mode();
1433
1434         /* Stick around until the controlee closes the client_fd */
1435         exitval = 0;
1436         for (;!control_client_terminate;) {
1437                 r = read(sock, &exitval, sizeof(exitval));
1438                 if (r == 0) {
1439                         debug2("Received EOF from master");
1440                         break;
1441                 }
1442                 if (r > 0)
1443                         debug2("Received exit status from master %d", exitval);
1444                 if (r == -1 && errno != EINTR)
1445                         fatal("%s: read %s", __func__, strerror(errno));
1446         }
1447
1448         if (control_client_terminate)
1449                 debug2("Exiting on signal %d", control_client_terminate);
1450
1451         close(sock);
1452
1453         leave_raw_mode();
1454
1455         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1456                 fprintf(stderr, "Connection to master closed.\r\n");
1457
1458         exit(exitval);
1459 }