ssh.c

   1 /* $OpenBSD: ssh.c,v 1.276 2006/04/25 08:02:27 dtucker 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/un.h>
  52
  53 #include <ctype.h>
  54 #ifdef HAVE_PATHS_H
  55 #include <paths.h>
  56 #endif
  57 #include <signal.h>
  58
  59 #include <openssl/evp.h>
  60 #include <openssl/err.h>
  61
  62 #include "ssh.h"
  63 #include "ssh1.h"
  64 #include "ssh2.h"
  65 #include "compat.h"
  66 #include "cipher.h"
  67 #include "xmalloc.h"
  68 #include "packet.h"
  69 #include "buffer.h"
  70 #include "bufaux.h"
  71 #include "channels.h"
  72 #include "key.h"
  73 #include "authfd.h"
  74 #include "authfile.h"
  75 #include "pathnames.h"
  76 #include "dispatch.h"
  77 #include "clientloop.h"
  78 #include "log.h"
  79 #include "readconf.h"
  80 #include "sshconnect.h"
  81 #include "misc.h"
  82 #include "kex.h"
  83 #include "mac.h"
  84 #include "sshpty.h"
  85 #include "match.h"
  86 #include "msg.h"
  87 #include "monitor_fdpass.h"
  88 #include "uidswap.h"
  89
  90 #ifdef SMARTCARD
  91 #include "scard.h"
  92 #endif
  93
  94 extern char *__progname;
  95
  96 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
  97 int debug_flag = 0;
  98
  99 /* Flag indicating whether a tty should be allocated */
 100 int tty_flag = 0;
 101 int no_tty_flag = 0;
 102 int force_tty_flag = 0;
 103
 104 /* don't exec a shell */
 105 int no_shell_flag = 0;
 106
 107 /*
 108  * Flag indicating that nothing should be read from stdin.  This can be set
 109  * on the command line.
 110  */
 111 int stdin_null_flag = 0;
 112
 113 /*
 114  * Flag indicating that ssh should fork after authentication.  This is useful
 115  * so that the passphrase can be entered manually, and then ssh goes to the
 116  * background.
 117  */
 118 int fork_after_authentication_flag = 0;
 119
 120 /*
 121  * General data structure for command line options and options configurable
 122  * in configuration files.  See readconf.h.
 123  */
 124 Options options;
 125
 126 /* optional user configfile */
 127 char *config = NULL;
 128
 129 /*
 130  * Name of the host we are connecting to.  This is the name given on the
 131  * command line, or the HostName specified for the user-supplied name in a
 132  * configuration file.
 133  */
 134 char *host;
 135
 136 /* socket address the host resolves to */
 137 struct sockaddr_storage hostaddr;
 138
 139 /* Private host keys. */
 140 Sensitive sensitive_data;
 141
 142 /* Original real UID. */
 143 uid_t original_real_uid;
 144 uid_t original_effective_uid;
 145
 146 /* command to be executed */
 147 Buffer command;
 148
 149 /* Should we execute a command or invoke a subsystem? */
 150 int subsystem_flag = 0;
 151
 152 /* # of replies received for global requests */
 153 static int client_global_request_id = 0;
 154
 155 /* pid of proxycommand child process */
 156 pid_t proxy_command_pid = 0;
 157
 158 /* fd to control socket */
 159 int control_fd = -1;
 160
 161 /* Multiplexing control command */
 162 static u_int mux_command = 0;
 163
 164 /* Only used in control client mode */
 165 volatile sig_atomic_t control_client_terminate = 0;
 166 u_int control_server_pid = 0;
 167
 168 /* Prints a help message to the user.  This function never returns. */
 169
 170 static void
 171 usage(void)
 172 {
 173         fprintf(stderr,
 174 "usage: ssh [-1246AaCfgkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 175 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 176 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 177 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 178 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 179 "           [-w tunnel:tunnel] [user@]hostname [command]\n"
 180         );
 181         exit(255);
 182 }
 183
 184 static int ssh_session(void);
 185 static int ssh_session2(void);
 186 static void load_public_identity_files(void);
 187 static void control_client(const char *path);
 188
 189 /*
 190  * Main program for the ssh client.
 191  */
 192 int
 193 main(int ac, char **av)
 194 {
 195         int i, opt, exit_status;
 196         char *p, *cp, *line, buf[256];
 197         struct stat st;
 198         struct passwd *pw;
 199         int dummy;
 200         extern int optind, optreset;
 201         extern char *optarg;
 202         struct servent *sp;
 203         Forward fwd;
 204
 205         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 206         sanitise_stdfd();
 207
 208         __progname = ssh_get_progname(av[0]);
 209         init_rng();
 210
 211         /*
 212          * Save the original real uid.  It will be needed later (uid-swapping
 213          * may clobber the real uid).
 214          */
 215         original_real_uid = getuid();
 216         original_effective_uid = geteuid();
 217
 218         /*
 219          * Use uid-swapping to give up root privileges for the duration of
 220          * option processing.  We will re-instantiate the rights when we are
 221          * ready to create the privileged port, and will permanently drop
 222          * them when the port has been created (actually, when the connection
 223          * has been made, as we may need to create the port several times).
 224          */
 225         PRIV_END;
 226
 227 #ifdef HAVE_SETRLIMIT
 228         /* If we are installed setuid root be careful to not drop core. */
 229         if (original_real_uid != original_effective_uid) {
 230                 struct rlimit rlim;
 231                 rlim.rlim_cur = rlim.rlim_max = 0;
 232                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 233                         fatal("setrlimit failed: %.100s", strerror(errno));
 234         }
 235 #endif
 236         /* Get user data. */
 237         pw = getpwuid(original_real_uid);
 238         if (!pw) {
 239                 logit("You don't exist, go away!");
 240                 exit(255);
 241         }
 242         /* Take a copy of the returned structure. */
 243         pw = pwcopy(pw);
 244
 245         /*
 246          * Set our umask to something reasonable, as some files are created
 247          * with the default umask.  This will make them world-readable but
 248          * writable only by the owner, which is ok for all files for which we
 249          * don't set the modes explicitly.
 250          */
 251         umask(022);
 252
 253         /* Initialize option structure to indicate that no values have been set. */
 254         initialize_options(&options);
 255
 256         /* Parse command-line arguments. */
 257         host = NULL;
 258
 259  again:
 260         while ((opt = getopt(ac, av,
 261             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:MNO:PR:S:TVw:XY")) != -1) {
 262                 switch (opt) {
 263                 case '1':
 264                         options.protocol = SSH_PROTO_1;
 265                         break;
 266                 case '2':
 267                         options.protocol = SSH_PROTO_2;
 268                         break;
 269                 case '4':
 270                         options.address_family = AF_INET;
 271                         break;
 272                 case '6':
 273                         options.address_family = AF_INET6;
 274                         break;
 275                 case 'n':
 276                         stdin_null_flag = 1;
 277                         break;
 278                 case 'f':
 279                         fork_after_authentication_flag = 1;
 280                         stdin_null_flag = 1;
 281                         break;
 282                 case 'x':
 283                         options.forward_x11 = 0;
 284                         break;
 285                 case 'X':
 286                         options.forward_x11 = 1;
 287                         break;
 288                 case 'Y':
 289                         options.forward_x11 = 1;
 290                         options.forward_x11_trusted = 1;
 291                         break;
 292                 case 'g':
 293                         options.gateway_ports = 1;
 294                         break;
 295                 case 'O':
 296                         if (strcmp(optarg, "check") == 0)
 297                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 298                         else if (strcmp(optarg, "exit") == 0)
 299                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 300                         else
 301                                 fatal("Invalid multiplex command.");
 302                         break;
 303                 case 'P':       /* deprecated */
 304                         options.use_privileged_port = 0;
 305                         break;
 306                 case 'a':
 307                         options.forward_agent = 0;
 308                         break;
 309                 case 'A':
 310                         options.forward_agent = 1;
 311                         break;
 312                 case 'k':
 313                         options.gss_deleg_creds = 0;
 314                         break;
 315                 case 'i':
 316                         if (stat(optarg, &st) < 0) {
 317                                 fprintf(stderr, "Warning: Identity file %s "
 318                                     "not accessible: %s.\n", optarg,
 319                                     strerror(errno));
 320                                 break;
 321                         }
 322                         if (options.num_identity_files >=
 323                             SSH_MAX_IDENTITY_FILES)
 324                                 fatal("Too many identity files specified "
 325                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 326                         options.identity_files[options.num_identity_files++] =
 327                             xstrdup(optarg);
 328                         break;
 329                 case 'I':
 330 #ifdef SMARTCARD
 331                         options.smartcard_device = xstrdup(optarg);
 332 #else
 333                         fprintf(stderr, "no support for smartcards.\n");
 334 #endif
 335                         break;
 336                 case 't':
 337                         if (tty_flag)
 338                                 force_tty_flag = 1;
 339                         tty_flag = 1;
 340                         break;
 341                 case 'v':
 342                         if (debug_flag == 0) {
 343                                 debug_flag = 1;
 344                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 345                         } else {
 346                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 347                                         options.log_level++;
 348                                 break;
 349                         }
 350                         /* FALLTHROUGH */
 351                 case 'V':
 352                         fprintf(stderr, "%s, %s\n",
 353                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 354                         if (opt == 'V')
 355                                 exit(0);
 356                         break;
 357                 case 'w':
 358                         if (options.tun_open == -1)
 359                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 360                         options.tun_local = a2tun(optarg, &options.tun_remote);
 361                         if (options.tun_local == SSH_TUNID_ERR) {
 362                                 fprintf(stderr, "Bad tun device '%s'\n", optarg);
 363                                 exit(255);
 364                         }
 365                         break;
 366                 case 'q':
 367                         options.log_level = SYSLOG_LEVEL_QUIET;
 368                         break;
 369                 case 'e':
 370                         if (optarg[0] == '^' && optarg[2] == 0 &&
 371                             (u_char) optarg[1] >= 64 &&
 372                             (u_char) optarg[1] < 128)
 373                                 options.escape_char = (u_char) optarg[1] & 31;
 374                         else if (strlen(optarg) == 1)
 375                                 options.escape_char = (u_char) optarg[0];
 376                         else if (strcmp(optarg, "none") == 0)
 377                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 378                         else {
 379                                 fprintf(stderr, "Bad escape character '%s'.\n",
 380                                     optarg);
 381                                 exit(255);
 382                         }
 383                         break;
 384                 case 'c':
 385                         if (ciphers_valid(optarg)) {
 386                                 /* SSH2 only */
 387                                 options.ciphers = xstrdup(optarg);
 388                                 options.cipher = SSH_CIPHER_INVALID;
 389                         } else {
 390                                 /* SSH1 only */
 391                                 options.cipher = cipher_number(optarg);
 392                                 if (options.cipher == -1) {
 393                                         fprintf(stderr,
 394                                             "Unknown cipher type '%s'\n",
 395                                             optarg);
 396                                         exit(255);
 397                                 }
 398                                 if (options.cipher == SSH_CIPHER_3DES)
 399                                         options.ciphers = "3des-cbc";
 400                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 401                                         options.ciphers = "blowfish-cbc";
 402                                 else
 403                                         options.ciphers = (char *)-1;
 404                         }
 405                         break;
 406                 case 'm':
 407                         if (mac_valid(optarg))
 408                                 options.macs = xstrdup(optarg);
 409                         else {
 410                                 fprintf(stderr, "Unknown mac type '%s'\n",
 411                                     optarg);
 412                                 exit(255);
 413                         }
 414                         break;
 415                 case 'M':
 416                         if (options.control_master == SSHCTL_MASTER_YES)
 417                                 options.control_master = SSHCTL_MASTER_ASK;
 418                         else
 419                                 options.control_master = SSHCTL_MASTER_YES;
 420                         break;
 421                 case 'p':
 422                         options.port = a2port(optarg);
 423                         if (options.port == 0) {
 424                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 425                                 exit(255);
 426                         }
 427                         break;
 428                 case 'l':
 429                         options.user = optarg;
 430                         break;
 431
 432                 case 'L':
 433                         if (parse_forward(&fwd, optarg))
 434                                 add_local_forward(&options, &fwd);
 435                         else {
 436                                 fprintf(stderr,
 437                                     "Bad local forwarding specification '%s'\n",
 438                                     optarg);
 439                                 exit(255);
 440                         }
 441                         break;
 442
 443                 case 'R':
 444                         if (parse_forward(&fwd, optarg)) {
 445                                 add_remote_forward(&options, &fwd);
 446                         } else {
 447                                 fprintf(stderr,
 448                                     "Bad remote forwarding specification "
 449                                     "'%s'\n", optarg);
 450                                 exit(255);
 451                         }
 452                         break;
 453
 454                 case 'D':
 455                         cp = p = xstrdup(optarg);
 456                         memset(&fwd, '\0', sizeof(fwd));
 457                         fwd.connect_host = "socks";
 458                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 459                                 fprintf(stderr, "Bad dynamic forwarding "
 460                                     "specification '%.100s'\n", optarg);
 461                                 exit(255);
 462                         }
 463                         if (cp != NULL) {
 464                                 fwd.listen_port = a2port(cp);
 465                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 466                         } else {
 467                                 fwd.listen_port = a2port(fwd.listen_host);
 468                                 fwd.listen_host = NULL;
 469                         }
 470
 471                         if (fwd.listen_port == 0) {
 472                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 473                                     optarg);
 474                                 exit(255);
 475                         }
 476                         add_local_forward(&options, &fwd);
 477                         xfree(p);
 478                         break;
 479
 480                 case 'C':
 481                         options.compression = 1;
 482                         break;
 483                 case 'N':
 484                         no_shell_flag = 1;
 485                         no_tty_flag = 1;
 486                         break;
 487                 case 'T':
 488                         no_tty_flag = 1;
 489                         break;
 490                 case 'o':
 491                         dummy = 1;
 492                         line = xstrdup(optarg);
 493                         if (process_config_line(&options, host ? host : "",
 494                             line, "command-line", 0, &dummy) != 0)
 495                                 exit(255);
 496                         xfree(line);
 497                         break;
 498                 case 's':
 499                         subsystem_flag = 1;
 500                         break;
 501                 case 'S':
 502                         if (options.control_path != NULL)
 503                                 free(options.control_path);
 504                         options.control_path = xstrdup(optarg);
 505                         break;
 506                 case 'b':
 507                         options.bind_address = optarg;
 508                         break;
 509                 case 'F':
 510                         config = optarg;
 511                         break;
 512                 default:
 513                         usage();
 514                 }
 515         }
 516
 517         ac -= optind;
 518         av += optind;
 519
 520         if (ac > 0 && !host && **av != '-') {
 521                 if (strrchr(*av, '@')) {
 522                         p = xstrdup(*av);
 523                         cp = strrchr(p, '@');
 524                         if (cp == NULL || cp == p)
 525                                 usage();
 526                         options.user = p;
 527                         *cp = '\0';
 528                         host = ++cp;
 529                 } else
 530                         host = *av;
 531                 if (ac > 1) {
 532                         optind = optreset = 1;
 533                         goto again;
 534                 }
 535                 ac--, av++;
 536         }
 537
 538         /* Check that we got a host name. */
 539         if (!host)
 540                 usage();
 541
 542         SSLeay_add_all_algorithms();
 543         ERR_load_crypto_strings();
 544
 545         /* Initialize the command to execute on remote host. */
 546         buffer_init(&command);
 547
 548         /*
 549          * Save the command to execute on the remote host in a buffer. There
 550          * is no limit on the length of the command, except by the maximum
 551          * packet size.  Also sets the tty flag if there is no command.
 552          */
 553         if (!ac) {
 554                 /* No command specified - execute shell on a tty. */
 555                 tty_flag = 1;
 556                 if (subsystem_flag) {
 557                         fprintf(stderr,
 558                             "You must specify a subsystem to invoke.\n");
 559                         usage();
 560                 }
 561         } else {
 562                 /* A command has been specified.  Store it into the buffer. */
 563                 for (i = 0; i < ac; i++) {
 564                         if (i)
 565                                 buffer_append(&command, " ", 1);
 566                         buffer_append(&command, av[i], strlen(av[i]));
 567                 }
 568         }
 569
 570         /* Cannot fork to background if no command. */
 571         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 572                 fatal("Cannot fork into background without a command to execute.");
 573
 574         /* Allocate a tty by default if no command specified. */
 575         if (buffer_len(&command) == 0)
 576                 tty_flag = 1;
 577
 578         /* Force no tty */
 579         if (no_tty_flag)
 580                 tty_flag = 0;
 581         /* Do not allocate a tty if stdin is not a tty. */
 582         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 583                 if (tty_flag)
 584                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 585                 tty_flag = 0;
 586         }
 587
 588         /*
 589          * Initialize "log" output.  Since we are the client all output
 590          * actually goes to stderr.
 591          */
 592         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 593             SYSLOG_FACILITY_USER, 1);
 594
 595         /*
 596          * Read per-user configuration file.  Ignore the system wide config
 597          * file if the user specifies a config file on the command line.
 598          */
 599         if (config != NULL) {
 600                 if (!read_config_file(config, host, &options, 0))
 601                         fatal("Can't open user config file %.100s: "
 602                             "%.100s", config, strerror(errno));
 603         } else  {
 604                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 605                     _PATH_SSH_USER_CONFFILE);
 606                 (void)read_config_file(buf, host, &options, 1);
 607
 608                 /* Read systemwide configuration file after use config. */
 609                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 610                     &options, 0);
 611         }
 612
 613         /* Fill configuration defaults. */
 614         fill_default_options(&options);
 615
 616         channel_set_af(options.address_family);
 617
 618         /* reinit */
 619         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 620
 621         seed_rng();
 622
 623         if (options.user == NULL)
 624                 options.user = xstrdup(pw->pw_name);
 625
 626         if (options.hostname != NULL)
 627                 host = options.hostname;
 628
 629         /* force lowercase for hostkey matching */
 630         if (options.host_key_alias != NULL) {
 631                 for (p = options.host_key_alias; *p; p++)
 632                         if (isupper(*p))
 633                                 *p = (char)tolower(*p);
 634         }
 635
 636         /* Get default port if port has not been set. */
 637         if (options.port == 0) {
 638                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 639                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 640         }
 641
 642         if (options.proxy_command != NULL &&
 643             strcmp(options.proxy_command, "none") == 0)
 644                 options.proxy_command = NULL;
 645         if (options.control_path != NULL &&
 646             strcmp(options.control_path, "none") == 0)
 647                 options.control_path = NULL;
 648
 649         if (options.control_path != NULL) {
 650                 char thishost[NI_MAXHOST];
 651
 652                 if (gethostname(thishost, sizeof(thishost)) == -1)
 653                         fatal("gethostname: %s", strerror(errno));
 654                 snprintf(buf, sizeof(buf), "%d", options.port);
 655                 cp = tilde_expand_filename(options.control_path,
 656                     original_real_uid);
 657                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 658                     "r", options.user, "l", thishost, (char *)NULL);
 659                 xfree(cp);
 660         }
 661         if (mux_command != 0 && options.control_path == NULL)
 662                 fatal("No ControlPath specified for \"-O\" command");
 663         if (options.control_path != NULL)
 664                 control_client(options.control_path);
 665
 666         /* Open a connection to the remote host. */
 667         if (ssh_connect(host, &hostaddr, options.port,
 668             options.address_family, options.connection_attempts,
 669 #ifdef HAVE_CYGWIN
 670             options.use_privileged_port,
 671 #else
 672             original_effective_uid == 0 && options.use_privileged_port,
 673 #endif
 674             options.proxy_command) != 0)
 675                 exit(255);
 676
 677         /*
 678          * If we successfully made the connection, load the host private key
 679          * in case we will need it later for combined rsa-rhosts
 680          * authentication. This must be done before releasing extra
 681          * privileges, because the file is only readable by root.
 682          * If we cannot access the private keys, load the public keys
 683          * instead and try to execute the ssh-keysign helper instead.
 684          */
 685         sensitive_data.nkeys = 0;
 686         sensitive_data.keys = NULL;
 687         sensitive_data.external_keysign = 0;
 688         if (options.rhosts_rsa_authentication ||
 689             options.hostbased_authentication) {
 690                 sensitive_data.nkeys = 3;
 691                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 692                     sizeof(Key));
 693
 694                 PRIV_START;
 695                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 696                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 697                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 698                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 699                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 700                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 701                 PRIV_END;
 702
 703                 if (options.hostbased_authentication == 1 &&
 704                     sensitive_data.keys[0] == NULL &&
 705                     sensitive_data.keys[1] == NULL &&
 706                     sensitive_data.keys[2] == NULL) {
 707                         sensitive_data.keys[1] = key_load_public(
 708                             _PATH_HOST_DSA_KEY_FILE, NULL);
 709                         sensitive_data.keys[2] = key_load_public(
 710                             _PATH_HOST_RSA_KEY_FILE, NULL);
 711                         sensitive_data.external_keysign = 1;
 712                 }
 713         }
 714         /*
 715          * Get rid of any extra privileges that we may have.  We will no
 716          * longer need them.  Also, extra privileges could make it very hard
 717          * to read identity files and other non-world-readable files from the
 718          * user's home directory if it happens to be on a NFS volume where
 719          * root is mapped to nobody.
 720          */
 721         if (original_effective_uid == 0) {
 722                 PRIV_START;
 723                 permanently_set_uid(pw);
 724         }
 725
 726         /*
 727          * Now that we are back to our own permissions, create ~/.ssh
 728          * directory if it doesn't already exist.
 729          */
 730         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 731         if (stat(buf, &st) < 0)
 732                 if (mkdir(buf, 0700) < 0)
 733                         error("Could not create directory '%.200s'.", buf);
 734
 735         /* load options.identity_files */
 736         load_public_identity_files();
 737
 738         /* Expand ~ in known host file names. */
 739         /* XXX mem-leaks: */
 740         options.system_hostfile =
 741             tilde_expand_filename(options.system_hostfile, original_real_uid);
 742         options.user_hostfile =
 743             tilde_expand_filename(options.user_hostfile, original_real_uid);
 744         options.system_hostfile2 =
 745             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 746         options.user_hostfile2 =
 747             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 748
 749         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 750
 751         /* Log into the remote system.  This never returns if the login fails. */
 752         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 753
 754         /* We no longer need the private host keys.  Clear them now. */
 755         if (sensitive_data.nkeys != 0) {
 756                 for (i = 0; i < sensitive_data.nkeys; i++) {
 757                         if (sensitive_data.keys[i] != NULL) {
 758                                 /* Destroys contents safely */
 759                                 debug3("clear hostkey %d", i);
 760                                 key_free(sensitive_data.keys[i]);
 761                                 sensitive_data.keys[i] = NULL;
 762                         }
 763                 }
 764                 xfree(sensitive_data.keys);
 765         }
 766         for (i = 0; i < options.num_identity_files; i++) {
 767                 if (options.identity_files[i]) {
 768                         xfree(options.identity_files[i]);
 769                         options.identity_files[i] = NULL;
 770                 }
 771                 if (options.identity_keys[i]) {
 772                         key_free(options.identity_keys[i]);
 773                         options.identity_keys[i] = NULL;
 774                 }
 775         }
 776
 777         exit_status = compat20 ? ssh_session2() : ssh_session();
 778         packet_close();
 779
 780         if (options.control_path != NULL && control_fd != -1)
 781                 unlink(options.control_path);
 782
 783         /*
 784          * Send SIGHUP to proxy command if used. We don't wait() in
 785          * case it hangs and instead rely on init to reap the child
 786          */
 787         if (proxy_command_pid > 1)
 788                 kill(proxy_command_pid, SIGHUP);
 789
 790         return exit_status;
 791 }
 792
 793 static void
 794 ssh_init_forwarding(void)
 795 {
 796         int success = 0;
 797         int i;
 798
 799         /* Initiate local TCP/IP port forwardings. */
 800         for (i = 0; i < options.num_local_forwards; i++) {
 801                 debug("Local connections to %.200s:%d forwarded to remote "
 802                     "address %.200s:%d",
 803                     (options.local_forwards[i].listen_host == NULL) ?
 804                     (options.gateway_ports ? "*" : "LOCALHOST") :
 805                     options.local_forwards[i].listen_host,
 806                     options.local_forwards[i].listen_port,
 807                     options.local_forwards[i].connect_host,
 808                     options.local_forwards[i].connect_port);
 809                 success += channel_setup_local_fwd_listener(
 810                     options.local_forwards[i].listen_host,
 811                     options.local_forwards[i].listen_port,
 812                     options.local_forwards[i].connect_host,
 813                     options.local_forwards[i].connect_port,
 814                     options.gateway_ports);
 815         }
 816         if (i > 0 && success == 0)
 817                 error("Could not request local forwarding.");
 818
 819         /* Initiate remote TCP/IP port forwardings. */
 820         for (i = 0; i < options.num_remote_forwards; i++) {
 821                 debug("Remote connections from %.200s:%d forwarded to "
 822                     "local address %.200s:%d",
 823                     (options.remote_forwards[i].listen_host == NULL) ?
 824                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 825                     options.remote_forwards[i].listen_port,
 826                     options.remote_forwards[i].connect_host,
 827                     options.remote_forwards[i].connect_port);
 828                 channel_request_remote_forwarding(
 829                     options.remote_forwards[i].listen_host,
 830                     options.remote_forwards[i].listen_port,
 831                     options.remote_forwards[i].connect_host,
 832                     options.remote_forwards[i].connect_port);
 833         }
 834 }
 835
 836 static void
 837 check_agent_present(void)
 838 {
 839         if (options.forward_agent) {
 840                 /* Clear agent forwarding if we don't have an agent. */
 841                 if (!ssh_agent_present())
 842                         options.forward_agent = 0;
 843         }
 844 }
 845
 846 static int
 847 ssh_session(void)
 848 {
 849         int type;
 850         int interactive = 0;
 851         int have_tty = 0;
 852         struct winsize ws;
 853         char *cp;
 854         const char *display;
 855
 856         /* Enable compression if requested. */
 857         if (options.compression) {
 858                 debug("Requesting compression at level %d.", options.compression_level);
 859
 860                 if (options.compression_level < 1 || options.compression_level > 9)
 861                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 862
 863                 /* Send the request. */
 864                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 865                 packet_put_int(options.compression_level);
 866                 packet_send();
 867                 packet_write_wait();
 868                 type = packet_read();
 869                 if (type == SSH_SMSG_SUCCESS)
 870                         packet_start_compression(options.compression_level);
 871                 else if (type == SSH_SMSG_FAILURE)
 872                         logit("Warning: Remote host refused compression.");
 873                 else
 874                         packet_disconnect("Protocol error waiting for compression response.");
 875         }
 876         /* Allocate a pseudo tty if appropriate. */
 877         if (tty_flag) {
 878                 debug("Requesting pty.");
 879
 880                 /* Start the packet. */
 881                 packet_start(SSH_CMSG_REQUEST_PTY);
 882
 883                 /* Store TERM in the packet.  There is no limit on the
 884                    length of the string. */
 885                 cp = getenv("TERM");
 886                 if (!cp)
 887                         cp = "";
 888                 packet_put_cstring(cp);
 889
 890                 /* Store window size in the packet. */
 891                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 892                         memset(&ws, 0, sizeof(ws));
 893                 packet_put_int((u_int)ws.ws_row);
 894                 packet_put_int((u_int)ws.ws_col);
 895                 packet_put_int((u_int)ws.ws_xpixel);
 896                 packet_put_int((u_int)ws.ws_ypixel);
 897
 898                 /* Store tty modes in the packet. */
 899                 tty_make_modes(fileno(stdin), NULL);
 900
 901                 /* Send the packet, and wait for it to leave. */
 902                 packet_send();
 903                 packet_write_wait();
 904
 905                 /* Read response from the server. */
 906                 type = packet_read();
 907                 if (type == SSH_SMSG_SUCCESS) {
 908                         interactive = 1;
 909                         have_tty = 1;
 910                 } else if (type == SSH_SMSG_FAILURE)
 911                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 912                 else
 913                         packet_disconnect("Protocol error waiting for pty request response.");
 914         }
 915         /* Request X11 forwarding if enabled and DISPLAY is set. */
 916         display = getenv("DISPLAY");
 917         if (options.forward_x11 && display != NULL) {
 918                 char *proto, *data;
 919                 /* Get reasonable local authentication information. */
 920                 client_x11_get_proto(display, options.xauth_location,
 921                     options.forward_x11_trusted, &proto, &data);
 922                 /* Request forwarding with authentication spoofing. */
 923                 debug("Requesting X11 forwarding with authentication spoofing.");
 924                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 925
 926                 /* Read response from the server. */
 927                 type = packet_read();
 928                 if (type == SSH_SMSG_SUCCESS) {
 929                         interactive = 1;
 930                 } else if (type == SSH_SMSG_FAILURE) {
 931                         logit("Warning: Remote host denied X11 forwarding.");
 932                 } else {
 933                         packet_disconnect("Protocol error waiting for X11 forwarding");
 934                 }
 935         }
 936         /* Tell the packet module whether this is an interactive session. */
 937         packet_set_interactive(interactive);
 938
 939         /* Request authentication agent forwarding if appropriate. */
 940         check_agent_present();
 941
 942         if (options.forward_agent) {
 943                 debug("Requesting authentication agent forwarding.");
 944                 auth_request_forwarding();
 945
 946                 /* Read response from the server. */
 947                 type = packet_read();
 948                 packet_check_eom();
 949                 if (type != SSH_SMSG_SUCCESS)
 950                         logit("Warning: Remote host denied authentication agent forwarding.");
 951         }
 952
 953         /* Initiate port forwardings. */
 954         ssh_init_forwarding();
 955
 956         /* If requested, let ssh continue in the background. */
 957         if (fork_after_authentication_flag)
 958                 if (daemon(1, 1) < 0)
 959                         fatal("daemon() failed: %.200s", strerror(errno));
 960
 961         /*
 962          * If a command was specified on the command line, execute the
 963          * command now. Otherwise request the server to start a shell.
 964          */
 965         if (buffer_len(&command) > 0) {
 966                 int len = buffer_len(&command);
 967                 if (len > 900)
 968                         len = 900;
 969                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 970                 packet_start(SSH_CMSG_EXEC_CMD);
 971                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 972                 packet_send();
 973                 packet_write_wait();
 974         } else {
 975                 debug("Requesting shell.");
 976                 packet_start(SSH_CMSG_EXEC_SHELL);
 977                 packet_send();
 978                 packet_write_wait();
 979         }
 980
 981         /* Enter the interactive session. */
 982         return client_loop(have_tty, tty_flag ?
 983             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
 984 }
 985
 986 static void
 987 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
 988 {
 989         int id, len;
 990
 991         id = packet_get_int();
 992         len = buffer_len(&command);
 993         if (len > 900)
 994                 len = 900;
 995         packet_check_eom();
 996         if (type == SSH2_MSG_CHANNEL_FAILURE)
 997                 fatal("Request for subsystem '%.*s' failed on channel %d",
 998                     len, (u_char *)buffer_ptr(&command), id);
 999 }
1000
1001 void
1002 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1003 {
1004         int i;
1005
1006         i = client_global_request_id++;
1007         if (i >= options.num_remote_forwards)
1008                 return;
1009         debug("remote forward %s for: listen %d, connect %s:%d",
1010             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1011             options.remote_forwards[i].listen_port,
1012             options.remote_forwards[i].connect_host,
1013             options.remote_forwards[i].connect_port);
1014         if (type == SSH2_MSG_REQUEST_FAILURE)
1015                 logit("Warning: remote port forwarding failed for listen "
1016                     "port %d", options.remote_forwards[i].listen_port);
1017 }
1018
1019 static void
1020 ssh_control_listener(void)
1021 {
1022         struct sockaddr_un addr;
1023         mode_t old_umask;
1024         int addr_len;
1025
1026         if (options.control_path == NULL ||
1027             options.control_master == SSHCTL_MASTER_NO)
1028                 return;
1029
1030         debug("setting up multiplex master socket");
1031
1032         memset(&addr, '\0', sizeof(addr));
1033         addr.sun_family = AF_UNIX;
1034         addr_len = offsetof(struct sockaddr_un, sun_path) +
1035             strlen(options.control_path) + 1;
1036
1037         if (strlcpy(addr.sun_path, options.control_path,
1038             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1039                 fatal("ControlPath too long");
1040
1041         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1042                 fatal("%s socket(): %s", __func__, strerror(errno));
1043
1044         old_umask = umask(0177);
1045         if (bind(control_fd, (struct sockaddr *)&addr, addr_len) == -1) {
1046                 control_fd = -1;
1047                 if (errno == EINVAL || errno == EADDRINUSE)
1048                         fatal("ControlSocket %s already exists",
1049                             options.control_path);
1050                 else
1051                         fatal("%s bind(): %s", __func__, strerror(errno));
1052         }
1053         umask(old_umask);
1054
1055         if (listen(control_fd, 64) == -1)
1056                 fatal("%s listen(): %s", __func__, strerror(errno));
1057
1058         set_nonblock(control_fd);
1059 }
1060
1061 /* request pty/x11/agent/tcpfwd/shell for channel */
1062 static void
1063 ssh_session2_setup(int id, void *arg)
1064 {
1065         extern char **environ;
1066         const char *display;
1067         int interactive = tty_flag;
1068
1069         display = getenv("DISPLAY");
1070         if (options.forward_x11 && display != NULL) {
1071                 char *proto, *data;
1072                 /* Get reasonable local authentication information. */
1073                 client_x11_get_proto(display, options.xauth_location,
1074                     options.forward_x11_trusted, &proto, &data);
1075                 /* Request forwarding with authentication spoofing. */
1076                 debug("Requesting X11 forwarding with authentication spoofing.");
1077                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1078                 interactive = 1;
1079                 /* XXX wait for reply */
1080         }
1081
1082         check_agent_present();
1083         if (options.forward_agent) {
1084                 debug("Requesting authentication agent forwarding.");
1085                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1086                 packet_send();
1087         }
1088
1089         if (options.tun_open != SSH_TUNMODE_NO) {
1090                 Channel *c;
1091                 int fd;
1092
1093                 debug("Requesting tun.");
1094                 if ((fd = tun_open(options.tun_local,
1095                     options.tun_open)) >= 0) {
1096                         c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1097                             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1098                             0, "tun", 1);
1099                         c->datagram = 1;
1100 #if defined(SSH_TUN_FILTER)
1101                         if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
1102                                 channel_register_filter(c->self, sys_tun_infilter,
1103                                     sys_tun_outfilter);
1104 #endif
1105                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1106                         packet_put_cstring("tun@openssh.com");
1107                         packet_put_int(c->self);
1108                         packet_put_int(c->local_window_max);
1109                         packet_put_int(c->local_maxpacket);
1110                         packet_put_int(options.tun_open);
1111                         packet_put_int(options.tun_remote);
1112                         packet_send();
1113                 }
1114         }
1115
1116         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1117             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1118
1119         packet_set_interactive(interactive);
1120 }
1121
1122 /* open new channel for a session */
1123 static int
1124 ssh_session2_open(void)
1125 {
1126         Channel *c;
1127         int window, packetmax, in, out, err;
1128
1129         if (stdin_null_flag) {
1130                 in = open(_PATH_DEVNULL, O_RDONLY);
1131         } else {
1132                 in = dup(STDIN_FILENO);
1133         }
1134         out = dup(STDOUT_FILENO);
1135         err = dup(STDERR_FILENO);
1136
1137         if (in < 0 || out < 0 || err < 0)
1138                 fatal("dup() in/out/err failed");
1139
1140         /* enable nonblocking unless tty */
1141         if (!isatty(in))
1142                 set_nonblock(in);
1143         if (!isatty(out))
1144                 set_nonblock(out);
1145         if (!isatty(err))
1146                 set_nonblock(err);
1147
1148         window = CHAN_SES_WINDOW_DEFAULT;
1149         packetmax = CHAN_SES_PACKET_DEFAULT;
1150         if (tty_flag) {
1151                 window >>= 1;
1152                 packetmax >>= 1;
1153         }
1154         c = channel_new(
1155             "session", SSH_CHANNEL_OPENING, in, out, err,
1156             window, packetmax, CHAN_EXTENDED_WRITE,
1157             "client-session", /*nonblock*/0);
1158
1159         debug3("ssh_session2_open: channel_new: %d", c->self);
1160
1161         channel_send_open(c->self);
1162         if (!no_shell_flag)
1163                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1164
1165         return c->self;
1166 }
1167
1168 static int
1169 ssh_session2(void)
1170 {
1171         int id = -1;
1172
1173         /* XXX should be pre-session */
1174         ssh_init_forwarding();
1175         ssh_control_listener();
1176
1177         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1178                 id = ssh_session2_open();
1179
1180         /* Execute a local command */
1181         if (options.local_command != NULL &&
1182             options.permit_local_command)
1183                 ssh_local_cmd(options.local_command);
1184
1185         /* If requested, let ssh continue in the background. */
1186         if (fork_after_authentication_flag)
1187                 if (daemon(1, 1) < 0)
1188                         fatal("daemon() failed: %.200s", strerror(errno));
1189
1190         return client_loop(tty_flag, tty_flag ?
1191             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1192 }
1193
1194 static void
1195 load_public_identity_files(void)
1196 {
1197         char *filename, *cp, thishost[NI_MAXHOST];
1198         int i = 0;
1199         Key *public;
1200         struct passwd *pw;
1201 #ifdef SMARTCARD
1202         Key **keys;
1203
1204         if (options.smartcard_device != NULL &&
1205             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1206             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1207                 int count = 0;
1208                 for (i = 0; keys[i] != NULL; i++) {
1209                         count++;
1210                         memmove(&options.identity_files[1], &options.identity_files[0],
1211                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1212                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1213                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1214                         options.num_identity_files++;
1215                         options.identity_keys[0] = keys[i];
1216                         options.identity_files[0] = sc_get_key_label(keys[i]);
1217                 }
1218                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1219                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1220                 i = count;
1221                 xfree(keys);
1222         }
1223 #endif /* SMARTCARD */
1224         if ((pw = getpwuid(original_real_uid)) == NULL)
1225                 fatal("load_public_identity_files: getpwuid failed");
1226         if (gethostname(thishost, sizeof(thishost)) == -1)
1227                 fatal("load_public_identity_files: gethostname: %s",
1228                     strerror(errno));
1229         for (; i < options.num_identity_files; i++) {
1230                 cp = tilde_expand_filename(options.identity_files[i],
1231                     original_real_uid);
1232                 filename = percent_expand(cp, "d", pw->pw_dir,
1233                     "u", pw->pw_name, "l", thishost, "h", host,
1234                     "r", options.user, (char *)NULL);
1235                 xfree(cp);
1236                 public = key_load_public(filename, NULL);
1237                 debug("identity file %s type %d", filename,
1238                     public ? public->type : -1);
1239                 xfree(options.identity_files[i]);
1240                 options.identity_files[i] = filename;
1241                 options.identity_keys[i] = public;
1242         }
1243 }
1244
1245 static void
1246 control_client_sighandler(int signo)
1247 {
1248         control_client_terminate = signo;
1249 }
1250
1251 static void
1252 control_client_sigrelay(int signo)
1253 {
1254         if (control_server_pid > 1)
1255                 kill(control_server_pid, signo);
1256 }
1257
1258 static int
1259 env_permitted(char *env)
1260 {
1261         int i;
1262         char name[1024], *cp;
1263
1264         if (strlcpy(name, env, sizeof(name)) >= sizeof(name))
1265                 fatal("env_permitted: name too long");
1266         if ((cp = strchr(name, '=')) == NULL)
1267                 return (0);
1268
1269         *cp = '\0';
1270
1271         for (i = 0; i < options.num_send_env; i++)
1272                 if (match_pattern(name, options.send_env[i]))
1273                         return (1);
1274
1275         return (0);
1276 }
1277
1278 static void
1279 control_client(const char *path)
1280 {
1281         struct sockaddr_un addr;
1282         int i, r, fd, sock, exitval, num_env, addr_len;
1283         Buffer m;
1284         char *term;
1285         extern char **environ;
1286         u_int  flags;
1287
1288         if (mux_command == 0)
1289                 mux_command = SSHMUX_COMMAND_OPEN;
1290
1291         switch (options.control_master) {
1292         case SSHCTL_MASTER_AUTO:
1293         case SSHCTL_MASTER_AUTO_ASK:
1294                 debug("auto-mux: Trying existing master");
1295                 /* FALLTHROUGH */
1296         case SSHCTL_MASTER_NO:
1297                 break;
1298         default:
1299                 return;
1300         }
1301
1302         memset(&addr, '\0', sizeof(addr));
1303         addr.sun_family = AF_UNIX;
1304         addr_len = offsetof(struct sockaddr_un, sun_path) +
1305             strlen(path) + 1;
1306
1307         if (strlcpy(addr.sun_path, path,
1308             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1309                 fatal("ControlPath too long");
1310
1311         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1312                 fatal("%s socket(): %s", __func__, strerror(errno));
1313
1314         if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) {
1315                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1316                         fatal("Control socket connect(%.100s): %s", path,
1317                             strerror(errno));
1318                 }
1319                 if (errno == ENOENT)
1320                         debug("Control socket \"%.100s\" does not exist", path);
1321                 else {
1322                         error("Control socket connect(%.100s): %s", path,
1323                             strerror(errno));
1324                 }
1325                 close(sock);
1326                 return;
1327         }
1328
1329         if (stdin_null_flag) {
1330                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1331                         fatal("open(/dev/null): %s", strerror(errno));
1332                 if (dup2(fd, STDIN_FILENO) == -1)
1333                         fatal("dup2: %s", strerror(errno));
1334                 if (fd > STDERR_FILENO)
1335                         close(fd);
1336         }
1337
1338         term = getenv("TERM");
1339
1340         flags = 0;
1341         if (tty_flag)
1342                 flags |= SSHMUX_FLAG_TTY;
1343         if (subsystem_flag)
1344                 flags |= SSHMUX_FLAG_SUBSYS;
1345         if (options.forward_x11)
1346                 flags |= SSHMUX_FLAG_X11_FWD;
1347         if (options.forward_agent)
1348                 flags |= SSHMUX_FLAG_AGENT_FWD;
1349
1350         buffer_init(&m);
1351
1352         /* Send our command to server */
1353         buffer_put_int(&m, mux_command);
1354         buffer_put_int(&m, flags);
1355         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1356                 fatal("%s: msg_send", __func__);
1357         buffer_clear(&m);
1358
1359         /* Get authorisation status and PID of controlee */
1360         if (ssh_msg_recv(sock, &m) == -1)
1361                 fatal("%s: msg_recv", __func__);
1362         if (buffer_get_char(&m) != SSHMUX_VER)
1363                 fatal("%s: wrong version", __func__);
1364         if (buffer_get_int(&m) != 1)
1365                 fatal("Connection to master denied");
1366         control_server_pid = buffer_get_int(&m);
1367
1368         buffer_clear(&m);
1369
1370         switch (mux_command) {
1371         case SSHMUX_COMMAND_ALIVE_CHECK:
1372                 fprintf(stderr, "Master running (pid=%d)\r\n",
1373                     control_server_pid);
1374                 exit(0);
1375         case SSHMUX_COMMAND_TERMINATE:
1376                 fprintf(stderr, "Exit request sent.\r\n");
1377                 exit(0);
1378         case SSHMUX_COMMAND_OPEN:
1379                 /* continue below */
1380                 break;
1381         default:
1382                 fatal("silly mux_command %d", mux_command);
1383         }
1384
1385         /* SSHMUX_COMMAND_OPEN */
1386         buffer_put_cstring(&m, term ? term : "");
1387         buffer_append(&command, "\0", 1);
1388         buffer_put_cstring(&m, buffer_ptr(&command));
1389
1390         if (options.num_send_env == 0 || environ == NULL) {
1391                 buffer_put_int(&m, 0);
1392         } else {
1393                 /* Pass environment */
1394                 num_env = 0;
1395                 for (i = 0; environ[i] != NULL; i++)
1396                         if (env_permitted(environ[i]))
1397                                 num_env++; /* Count */
1398
1399                 buffer_put_int(&m, num_env);
1400
1401                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1402                         if (env_permitted(environ[i])) {
1403                                 num_env--;
1404                                 buffer_put_cstring(&m, environ[i]);
1405                         }
1406         }
1407
1408         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1409                 fatal("%s: msg_send", __func__);
1410
1411         mm_send_fd(sock, STDIN_FILENO);
1412         mm_send_fd(sock, STDOUT_FILENO);
1413         mm_send_fd(sock, STDERR_FILENO);
1414
1415         /* Wait for reply, so master has a chance to gather ttymodes */
1416         buffer_clear(&m);
1417         if (ssh_msg_recv(sock, &m) == -1)
1418                 fatal("%s: msg_recv", __func__);
1419         if (buffer_get_char(&m) != SSHMUX_VER)
1420                 fatal("%s: wrong version", __func__);
1421         buffer_free(&m);
1422
1423         signal(SIGHUP, control_client_sighandler);
1424         signal(SIGINT, control_client_sighandler);
1425         signal(SIGTERM, control_client_sighandler);
1426         signal(SIGWINCH, control_client_sigrelay);
1427
1428         if (tty_flag)
1429                 enter_raw_mode();
1430
1431         /* Stick around until the controlee closes the client_fd */
1432         exitval = 0;
1433         for (;!control_client_terminate;) {
1434                 r = read(sock, &exitval, sizeof(exitval));
1435                 if (r == 0) {
1436                         debug2("Received EOF from master");
1437                         break;
1438                 }
1439                 if (r > 0)
1440                         debug2("Received exit status from master %d", exitval);
1441                 if (r == -1 && errno != EINTR)
1442                         fatal("%s: read %s", __func__, strerror(errno));
1443         }
1444
1445         if (control_client_terminate)
1446                 debug2("Exiting on signal %d", control_client_terminate);
1447
1448         close(sock);
1449
1450         leave_raw_mode();
1451
1452         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1453                 fprintf(stderr, "Connection to master closed.\r\n");
1454
1455         exit(exitval);
1456 }