ssh.c

   1 /* $OpenBSD: ssh.c,v 1.290 2006/07/26 13:57:17 stevesk Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * Ssh client program.  This program can be used to log into a remote machine.
   7  * The software supports strong authentication, encryption, and forwarding
   8  * of X11, TCP/IP, and authentication connections.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  17  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  18  *
  19  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  20  * in Canada (German citizen).
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the above copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  *
  31  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  32  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  34  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  35  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  36  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  37  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  38  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  39  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  40  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  41  */
  42
  43 #include "includes.h"
  44
  45 #include <sys/types.h>
  46 #ifdef HAVE_SYS_STAT_H
  47 # include <sys/stat.h>
  48 #endif
  49 #include <sys/resource.h>
  50 #include <sys/ioctl.h>
  51 #include <sys/socket.h>
  52 #include <sys/un.h>
  53
  54 #include <ctype.h>
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #include <netdb.h>
  58 #ifdef HAVE_PATHS_H
  59 #include <paths.h>
  60 #endif
  61 #include <pwd.h>
  62 #include <signal.h>
  63 #include <stddef.h>
  64 #include <stdlib.h>
  65 #include <string.h>
  66 #include <unistd.h>
  67
  68 #include <openssl/evp.h>
  69 #include <openssl/err.h>
  70
  71 #include "ssh.h"
  72 #include "ssh1.h"
  73 #include "ssh2.h"
  74 #include "compat.h"
  75 #include "cipher.h"
  76 #include "xmalloc.h"
  77 #include "packet.h"
  78 #include "buffer.h"
  79 #include "bufaux.h"
  80 #include "channels.h"
  81 #include "key.h"
  82 #include "authfd.h"
  83 #include "authfile.h"
  84 #include "pathnames.h"
  85 #include "dispatch.h"
  86 #include "clientloop.h"
  87 #include "log.h"
  88 #include "readconf.h"
  89 #include "sshconnect.h"
  90 #include "misc.h"
  91 #include "kex.h"
  92 #include "mac.h"
  93 #include "sshpty.h"
  94 #include "match.h"
  95 #include "msg.h"
  96 #include "monitor_fdpass.h"
  97 #include "uidswap.h"
  98 #include "version.h"
  99
 100 #ifdef SMARTCARD
 101 #include "scard.h"
 102 #endif
 103
 104 extern char *__progname;
 105
 106 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
 107 int debug_flag = 0;
 108
 109 /* Flag indicating whether a tty should be allocated */
 110 int tty_flag = 0;
 111 int no_tty_flag = 0;
 112 int force_tty_flag = 0;
 113
 114 /* don't exec a shell */
 115 int no_shell_flag = 0;
 116
 117 /*
 118  * Flag indicating that nothing should be read from stdin.  This can be set
 119  * on the command line.
 120  */
 121 int stdin_null_flag = 0;
 122
 123 /*
 124  * Flag indicating that ssh should fork after authentication.  This is useful
 125  * so that the passphrase can be entered manually, and then ssh goes to the
 126  * background.
 127  */
 128 int fork_after_authentication_flag = 0;
 129
 130 /*
 131  * General data structure for command line options and options configurable
 132  * in configuration files.  See readconf.h.
 133  */
 134 Options options;
 135
 136 /* optional user configfile */
 137 char *config = NULL;
 138
 139 /*
 140  * Name of the host we are connecting to.  This is the name given on the
 141  * command line, or the HostName specified for the user-supplied name in a
 142  * configuration file.
 143  */
 144 char *host;
 145
 146 /* socket address the host resolves to */
 147 struct sockaddr_storage hostaddr;
 148
 149 /* Private host keys. */
 150 Sensitive sensitive_data;
 151
 152 /* Original real UID. */
 153 uid_t original_real_uid;
 154 uid_t original_effective_uid;
 155
 156 /* command to be executed */
 157 Buffer command;
 158
 159 /* Should we execute a command or invoke a subsystem? */
 160 int subsystem_flag = 0;
 161
 162 /* # of replies received for global requests */
 163 static int client_global_request_id = 0;
 164
 165 /* pid of proxycommand child process */
 166 pid_t proxy_command_pid = 0;
 167
 168 /* fd to control socket */
 169 int control_fd = -1;
 170
 171 /* Multiplexing control command */
 172 static u_int mux_command = 0;
 173
 174 /* Only used in control client mode */
 175 volatile sig_atomic_t control_client_terminate = 0;
 176 u_int control_server_pid = 0;
 177
 178 /* Prints a help message to the user.  This function never returns. */
 179
 180 static void
 181 usage(void)
 182 {
 183         fprintf(stderr,
 184 "usage: ssh [-1246AaCfgkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 185 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 186 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 187 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 188 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 189 "           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
 190         );
 191         exit(255);
 192 }
 193
 194 static int ssh_session(void);
 195 static int ssh_session2(void);
 196 static void load_public_identity_files(void);
 197 static void control_client(const char *path);
 198
 199 /*
 200  * Main program for the ssh client.
 201  */
 202 int
 203 main(int ac, char **av)
 204 {
 205         int i, opt, exit_status;
 206         char *p, *cp, *line, buf[256];
 207         struct stat st;
 208         struct passwd *pw;
 209         int dummy;
 210         extern int optind, optreset;
 211         extern char *optarg;
 212         struct servent *sp;
 213         Forward fwd;
 214
 215         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 216         sanitise_stdfd();
 217
 218         __progname = ssh_get_progname(av[0]);
 219         init_rng();
 220
 221         /*
 222          * Save the original real uid.  It will be needed later (uid-swapping
 223          * may clobber the real uid).
 224          */
 225         original_real_uid = getuid();
 226         original_effective_uid = geteuid();
 227
 228         /*
 229          * Use uid-swapping to give up root privileges for the duration of
 230          * option processing.  We will re-instantiate the rights when we are
 231          * ready to create the privileged port, and will permanently drop
 232          * them when the port has been created (actually, when the connection
 233          * has been made, as we may need to create the port several times).
 234          */
 235         PRIV_END;
 236
 237 #ifdef HAVE_SETRLIMIT
 238         /* If we are installed setuid root be careful to not drop core. */
 239         if (original_real_uid != original_effective_uid) {
 240                 struct rlimit rlim;
 241                 rlim.rlim_cur = rlim.rlim_max = 0;
 242                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 243                         fatal("setrlimit failed: %.100s", strerror(errno));
 244         }
 245 #endif
 246         /* Get user data. */
 247         pw = getpwuid(original_real_uid);
 248         if (!pw) {
 249                 logit("You don't exist, go away!");
 250                 exit(255);
 251         }
 252         /* Take a copy of the returned structure. */
 253         pw = pwcopy(pw);
 254
 255         /*
 256          * Set our umask to something reasonable, as some files are created
 257          * with the default umask.  This will make them world-readable but
 258          * writable only by the owner, which is ok for all files for which we
 259          * don't set the modes explicitly.
 260          */
 261         umask(022);
 262
 263         /* Initialize option structure to indicate that no values have been set. */
 264         initialize_options(&options);
 265
 266         /* Parse command-line arguments. */
 267         host = NULL;
 268
 269  again:
 270         while ((opt = getopt(ac, av,
 271             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:MNO:PR:S:TVw:XY")) != -1) {
 272                 switch (opt) {
 273                 case '1':
 274                         options.protocol = SSH_PROTO_1;
 275                         break;
 276                 case '2':
 277                         options.protocol = SSH_PROTO_2;
 278                         break;
 279                 case '4':
 280                         options.address_family = AF_INET;
 281                         break;
 282                 case '6':
 283                         options.address_family = AF_INET6;
 284                         break;
 285                 case 'n':
 286                         stdin_null_flag = 1;
 287                         break;
 288                 case 'f':
 289                         fork_after_authentication_flag = 1;
 290                         stdin_null_flag = 1;
 291                         break;
 292                 case 'x':
 293                         options.forward_x11 = 0;
 294                         break;
 295                 case 'X':
 296                         options.forward_x11 = 1;
 297                         break;
 298                 case 'Y':
 299                         options.forward_x11 = 1;
 300                         options.forward_x11_trusted = 1;
 301                         break;
 302                 case 'g':
 303                         options.gateway_ports = 1;
 304                         break;
 305                 case 'O':
 306                         if (strcmp(optarg, "check") == 0)
 307                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 308                         else if (strcmp(optarg, "exit") == 0)
 309                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 310                         else
 311                                 fatal("Invalid multiplex command.");
 312                         break;
 313                 case 'P':       /* deprecated */
 314                         options.use_privileged_port = 0;
 315                         break;
 316                 case 'a':
 317                         options.forward_agent = 0;
 318                         break;
 319                 case 'A':
 320                         options.forward_agent = 1;
 321                         break;
 322                 case 'k':
 323                         options.gss_deleg_creds = 0;
 324                         break;
 325                 case 'i':
 326                         if (stat(optarg, &st) < 0) {
 327                                 fprintf(stderr, "Warning: Identity file %s "
 328                                     "not accessible: %s.\n", optarg,
 329                                     strerror(errno));
 330                                 break;
 331                         }
 332                         if (options.num_identity_files >=
 333                             SSH_MAX_IDENTITY_FILES)
 334                                 fatal("Too many identity files specified "
 335                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 336                         options.identity_files[options.num_identity_files++] =
 337                             xstrdup(optarg);
 338                         break;
 339                 case 'I':
 340 #ifdef SMARTCARD
 341                         options.smartcard_device = xstrdup(optarg);
 342 #else
 343                         fprintf(stderr, "no support for smartcards.\n");
 344 #endif
 345                         break;
 346                 case 't':
 347                         if (tty_flag)
 348                                 force_tty_flag = 1;
 349                         tty_flag = 1;
 350                         break;
 351                 case 'v':
 352                         if (debug_flag == 0) {
 353                                 debug_flag = 1;
 354                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 355                         } else {
 356                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 357                                         options.log_level++;
 358                                 break;
 359                         }
 360                         /* FALLTHROUGH */
 361                 case 'V':
 362                         fprintf(stderr, "%s, %s\n",
 363                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 364                         if (opt == 'V')
 365                                 exit(0);
 366                         break;
 367                 case 'w':
 368                         if (options.tun_open == -1)
 369                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 370                         options.tun_local = a2tun(optarg, &options.tun_remote);
 371                         if (options.tun_local == SSH_TUNID_ERR) {
 372                                 fprintf(stderr, "Bad tun device '%s'\n", optarg);
 373                                 exit(255);
 374                         }
 375                         break;
 376                 case 'q':
 377                         options.log_level = SYSLOG_LEVEL_QUIET;
 378                         break;
 379                 case 'e':
 380                         if (optarg[0] == '^' && optarg[2] == 0 &&
 381                             (u_char) optarg[1] >= 64 &&
 382                             (u_char) optarg[1] < 128)
 383                                 options.escape_char = (u_char) optarg[1] & 31;
 384                         else if (strlen(optarg) == 1)
 385                                 options.escape_char = (u_char) optarg[0];
 386                         else if (strcmp(optarg, "none") == 0)
 387                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 388                         else {
 389                                 fprintf(stderr, "Bad escape character '%s'.\n",
 390                                     optarg);
 391                                 exit(255);
 392                         }
 393                         break;
 394                 case 'c':
 395                         if (ciphers_valid(optarg)) {
 396                                 /* SSH2 only */
 397                                 options.ciphers = xstrdup(optarg);
 398                                 options.cipher = SSH_CIPHER_INVALID;
 399                         } else {
 400                                 /* SSH1 only */
 401                                 options.cipher = cipher_number(optarg);
 402                                 if (options.cipher == -1) {
 403                                         fprintf(stderr,
 404                                             "Unknown cipher type '%s'\n",
 405                                             optarg);
 406                                         exit(255);
 407                                 }
 408                                 if (options.cipher == SSH_CIPHER_3DES)
 409                                         options.ciphers = "3des-cbc";
 410                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 411                                         options.ciphers = "blowfish-cbc";
 412                                 else
 413                                         options.ciphers = (char *)-1;
 414                         }
 415                         break;
 416                 case 'm':
 417                         if (mac_valid(optarg))
 418                                 options.macs = xstrdup(optarg);
 419                         else {
 420                                 fprintf(stderr, "Unknown mac type '%s'\n",
 421                                     optarg);
 422                                 exit(255);
 423                         }
 424                         break;
 425                 case 'M':
 426                         if (options.control_master == SSHCTL_MASTER_YES)
 427                                 options.control_master = SSHCTL_MASTER_ASK;
 428                         else
 429                                 options.control_master = SSHCTL_MASTER_YES;
 430                         break;
 431                 case 'p':
 432                         options.port = a2port(optarg);
 433                         if (options.port == 0) {
 434                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 435                                 exit(255);
 436                         }
 437                         break;
 438                 case 'l':
 439                         options.user = optarg;
 440                         break;
 441
 442                 case 'L':
 443                         if (parse_forward(&fwd, optarg))
 444                                 add_local_forward(&options, &fwd);
 445                         else {
 446                                 fprintf(stderr,
 447                                     "Bad local forwarding specification '%s'\n",
 448                                     optarg);
 449                                 exit(255);
 450                         }
 451                         break;
 452
 453                 case 'R':
 454                         if (parse_forward(&fwd, optarg)) {
 455                                 add_remote_forward(&options, &fwd);
 456                         } else {
 457                                 fprintf(stderr,
 458                                     "Bad remote forwarding specification "
 459                                     "'%s'\n", optarg);
 460                                 exit(255);
 461                         }
 462                         break;
 463
 464                 case 'D':
 465                         cp = p = xstrdup(optarg);
 466                         memset(&fwd, '\0', sizeof(fwd));
 467                         fwd.connect_host = "socks";
 468                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 469                                 fprintf(stderr, "Bad dynamic forwarding "
 470                                     "specification '%.100s'\n", optarg);
 471                                 exit(255);
 472                         }
 473                         if (cp != NULL) {
 474                                 fwd.listen_port = a2port(cp);
 475                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 476                         } else {
 477                                 fwd.listen_port = a2port(fwd.listen_host);
 478                                 fwd.listen_host = NULL;
 479                         }
 480
 481                         if (fwd.listen_port == 0) {
 482                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 483                                     optarg);
 484                                 exit(255);
 485                         }
 486                         add_local_forward(&options, &fwd);
 487                         xfree(p);
 488                         break;
 489
 490                 case 'C':
 491                         options.compression = 1;
 492                         break;
 493                 case 'N':
 494                         no_shell_flag = 1;
 495                         no_tty_flag = 1;
 496                         break;
 497                 case 'T':
 498                         no_tty_flag = 1;
 499                         break;
 500                 case 'o':
 501                         dummy = 1;
 502                         line = xstrdup(optarg);
 503                         if (process_config_line(&options, host ? host : "",
 504                             line, "command-line", 0, &dummy) != 0)
 505                                 exit(255);
 506                         xfree(line);
 507                         break;
 508                 case 's':
 509                         subsystem_flag = 1;
 510                         break;
 511                 case 'S':
 512                         if (options.control_path != NULL)
 513                                 free(options.control_path);
 514                         options.control_path = xstrdup(optarg);
 515                         break;
 516                 case 'b':
 517                         options.bind_address = optarg;
 518                         break;
 519                 case 'F':
 520                         config = optarg;
 521                         break;
 522                 default:
 523                         usage();
 524                 }
 525         }
 526
 527         ac -= optind;
 528         av += optind;
 529
 530         if (ac > 0 && !host && **av != '-') {
 531                 if (strrchr(*av, '@')) {
 532                         p = xstrdup(*av);
 533                         cp = strrchr(p, '@');
 534                         if (cp == NULL || cp == p)
 535                                 usage();
 536                         options.user = p;
 537                         *cp = '\0';
 538                         host = ++cp;
 539                 } else
 540                         host = *av;
 541                 if (ac > 1) {
 542                         optind = optreset = 1;
 543                         goto again;
 544                 }
 545                 ac--, av++;
 546         }
 547
 548         /* Check that we got a host name. */
 549         if (!host)
 550                 usage();
 551
 552         SSLeay_add_all_algorithms();
 553         ERR_load_crypto_strings();
 554
 555         /* Initialize the command to execute on remote host. */
 556         buffer_init(&command);
 557
 558         /*
 559          * Save the command to execute on the remote host in a buffer. There
 560          * is no limit on the length of the command, except by the maximum
 561          * packet size.  Also sets the tty flag if there is no command.
 562          */
 563         if (!ac) {
 564                 /* No command specified - execute shell on a tty. */
 565                 tty_flag = 1;
 566                 if (subsystem_flag) {
 567                         fprintf(stderr,
 568                             "You must specify a subsystem to invoke.\n");
 569                         usage();
 570                 }
 571         } else {
 572                 /* A command has been specified.  Store it into the buffer. */
 573                 for (i = 0; i < ac; i++) {
 574                         if (i)
 575                                 buffer_append(&command, " ", 1);
 576                         buffer_append(&command, av[i], strlen(av[i]));
 577                 }
 578         }
 579
 580         /* Cannot fork to background if no command. */
 581         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 582                 fatal("Cannot fork into background without a command to execute.");
 583
 584         /* Allocate a tty by default if no command specified. */
 585         if (buffer_len(&command) == 0)
 586                 tty_flag = 1;
 587
 588         /* Force no tty */
 589         if (no_tty_flag)
 590                 tty_flag = 0;
 591         /* Do not allocate a tty if stdin is not a tty. */
 592         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 593                 if (tty_flag)
 594                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 595                 tty_flag = 0;
 596         }
 597
 598         /*
 599          * Initialize "log" output.  Since we are the client all output
 600          * actually goes to stderr.
 601          */
 602         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 603             SYSLOG_FACILITY_USER, 1);
 604
 605         /*
 606          * Read per-user configuration file.  Ignore the system wide config
 607          * file if the user specifies a config file on the command line.
 608          */
 609         if (config != NULL) {
 610                 if (!read_config_file(config, host, &options, 0))
 611                         fatal("Can't open user config file %.100s: "
 612                             "%.100s", config, strerror(errno));
 613         } else  {
 614                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 615                     _PATH_SSH_USER_CONFFILE);
 616                 (void)read_config_file(buf, host, &options, 1);
 617
 618                 /* Read systemwide configuration file after use config. */
 619                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 620                     &options, 0);
 621         }
 622
 623         /* Fill configuration defaults. */
 624         fill_default_options(&options);
 625
 626         channel_set_af(options.address_family);
 627
 628         /* reinit */
 629         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 630
 631         seed_rng();
 632
 633         if (options.user == NULL)
 634                 options.user = xstrdup(pw->pw_name);
 635
 636         if (options.hostname != NULL)
 637                 host = options.hostname;
 638
 639         /* force lowercase for hostkey matching */
 640         if (options.host_key_alias != NULL) {
 641                 for (p = options.host_key_alias; *p; p++)
 642                         if (isupper(*p))
 643                                 *p = (char)tolower(*p);
 644         }
 645
 646         /* Get default port if port has not been set. */
 647         if (options.port == 0) {
 648                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 649                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 650         }
 651
 652         if (options.proxy_command != NULL &&
 653             strcmp(options.proxy_command, "none") == 0)
 654                 options.proxy_command = NULL;
 655         if (options.control_path != NULL &&
 656             strcmp(options.control_path, "none") == 0)
 657                 options.control_path = NULL;
 658
 659         if (options.control_path != NULL) {
 660                 char thishost[NI_MAXHOST];
 661
 662                 if (gethostname(thishost, sizeof(thishost)) == -1)
 663                         fatal("gethostname: %s", strerror(errno));
 664                 snprintf(buf, sizeof(buf), "%d", options.port);
 665                 cp = tilde_expand_filename(options.control_path,
 666                     original_real_uid);
 667                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 668                     "r", options.user, "l", thishost, (char *)NULL);
 669                 xfree(cp);
 670         }
 671         if (mux_command != 0 && options.control_path == NULL)
 672                 fatal("No ControlPath specified for \"-O\" command");
 673         if (options.control_path != NULL)
 674                 control_client(options.control_path);
 675
 676         /* Open a connection to the remote host. */
 677         if (ssh_connect(host, &hostaddr, options.port,
 678             options.address_family, options.connection_attempts,
 679 #ifdef HAVE_CYGWIN
 680             options.use_privileged_port,
 681 #else
 682             original_effective_uid == 0 && options.use_privileged_port,
 683 #endif
 684             options.proxy_command) != 0)
 685                 exit(255);
 686
 687         /*
 688          * If we successfully made the connection, load the host private key
 689          * in case we will need it later for combined rsa-rhosts
 690          * authentication. This must be done before releasing extra
 691          * privileges, because the file is only readable by root.
 692          * If we cannot access the private keys, load the public keys
 693          * instead and try to execute the ssh-keysign helper instead.
 694          */
 695         sensitive_data.nkeys = 0;
 696         sensitive_data.keys = NULL;
 697         sensitive_data.external_keysign = 0;
 698         if (options.rhosts_rsa_authentication ||
 699             options.hostbased_authentication) {
 700                 sensitive_data.nkeys = 3;
 701                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 702                     sizeof(Key));
 703
 704                 PRIV_START;
 705                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 706                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 707                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 708                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 709                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 710                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 711                 PRIV_END;
 712
 713                 if (options.hostbased_authentication == 1 &&
 714                     sensitive_data.keys[0] == NULL &&
 715                     sensitive_data.keys[1] == NULL &&
 716                     sensitive_data.keys[2] == NULL) {
 717                         sensitive_data.keys[1] = key_load_public(
 718                             _PATH_HOST_DSA_KEY_FILE, NULL);
 719                         sensitive_data.keys[2] = key_load_public(
 720                             _PATH_HOST_RSA_KEY_FILE, NULL);
 721                         sensitive_data.external_keysign = 1;
 722                 }
 723         }
 724         /*
 725          * Get rid of any extra privileges that we may have.  We will no
 726          * longer need them.  Also, extra privileges could make it very hard
 727          * to read identity files and other non-world-readable files from the
 728          * user's home directory if it happens to be on a NFS volume where
 729          * root is mapped to nobody.
 730          */
 731         if (original_effective_uid == 0) {
 732                 PRIV_START;
 733                 permanently_set_uid(pw);
 734         }
 735
 736         /*
 737          * Now that we are back to our own permissions, create ~/.ssh
 738          * directory if it doesn't already exist.
 739          */
 740         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 741         if (stat(buf, &st) < 0)
 742                 if (mkdir(buf, 0700) < 0)
 743                         error("Could not create directory '%.200s'.", buf);
 744
 745         /* load options.identity_files */
 746         load_public_identity_files();
 747
 748         /* Expand ~ in known host file names. */
 749         /* XXX mem-leaks: */
 750         options.system_hostfile =
 751             tilde_expand_filename(options.system_hostfile, original_real_uid);
 752         options.user_hostfile =
 753             tilde_expand_filename(options.user_hostfile, original_real_uid);
 754         options.system_hostfile2 =
 755             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 756         options.user_hostfile2 =
 757             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 758
 759         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 760
 761         /* Log into the remote system.  This never returns if the login fails. */
 762         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 763
 764         /* We no longer need the private host keys.  Clear them now. */
 765         if (sensitive_data.nkeys != 0) {
 766                 for (i = 0; i < sensitive_data.nkeys; i++) {
 767                         if (sensitive_data.keys[i] != NULL) {
 768                                 /* Destroys contents safely */
 769                                 debug3("clear hostkey %d", i);
 770                                 key_free(sensitive_data.keys[i]);
 771                                 sensitive_data.keys[i] = NULL;
 772                         }
 773                 }
 774                 xfree(sensitive_data.keys);
 775         }
 776         for (i = 0; i < options.num_identity_files; i++) {
 777                 if (options.identity_files[i]) {
 778                         xfree(options.identity_files[i]);
 779                         options.identity_files[i] = NULL;
 780                 }
 781                 if (options.identity_keys[i]) {
 782                         key_free(options.identity_keys[i]);
 783                         options.identity_keys[i] = NULL;
 784                 }
 785         }
 786
 787         exit_status = compat20 ? ssh_session2() : ssh_session();
 788         packet_close();
 789
 790         if (options.control_path != NULL && control_fd != -1)
 791                 unlink(options.control_path);
 792
 793         /*
 794          * Send SIGHUP to proxy command if used. We don't wait() in
 795          * case it hangs and instead rely on init to reap the child
 796          */
 797         if (proxy_command_pid > 1)
 798                 kill(proxy_command_pid, SIGHUP);
 799
 800         return exit_status;
 801 }
 802
 803 static void
 804 ssh_init_forwarding(void)
 805 {
 806         int success = 0;
 807         int i;
 808
 809         /* Initiate local TCP/IP port forwardings. */
 810         for (i = 0; i < options.num_local_forwards; i++) {
 811                 debug("Local connections to %.200s:%d forwarded to remote "
 812                     "address %.200s:%d",
 813                     (options.local_forwards[i].listen_host == NULL) ?
 814                     (options.gateway_ports ? "*" : "LOCALHOST") :
 815                     options.local_forwards[i].listen_host,
 816                     options.local_forwards[i].listen_port,
 817                     options.local_forwards[i].connect_host,
 818                     options.local_forwards[i].connect_port);
 819                 success += channel_setup_local_fwd_listener(
 820                     options.local_forwards[i].listen_host,
 821                     options.local_forwards[i].listen_port,
 822                     options.local_forwards[i].connect_host,
 823                     options.local_forwards[i].connect_port,
 824                     options.gateway_ports);
 825         }
 826         if (i > 0 && success != i && options.exit_on_forward_failure)
 827                 fatal("Could not request local forwarding.");
 828         if (i > 0 && success == 0)
 829                 error("Could not request local forwarding.");
 830
 831         /* Initiate remote TCP/IP port forwardings. */
 832         for (i = 0; i < options.num_remote_forwards; i++) {
 833                 debug("Remote connections from %.200s:%d forwarded to "
 834                     "local address %.200s:%d",
 835                     (options.remote_forwards[i].listen_host == NULL) ?
 836                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 837                     options.remote_forwards[i].listen_port,
 838                     options.remote_forwards[i].connect_host,
 839                     options.remote_forwards[i].connect_port);
 840                 if (channel_request_remote_forwarding(
 841                     options.remote_forwards[i].listen_host,
 842                     options.remote_forwards[i].listen_port,
 843                     options.remote_forwards[i].connect_host,
 844                     options.remote_forwards[i].connect_port) < 0) {
 845                         if (options.exit_on_forward_failure)
 846                                 fatal("Could not request remote forwarding.");
 847                         else
 848                                 logit("Warning: Could not request remote "
 849                                     "forwarding.");
 850                 }
 851         }
 852 }
 853
 854 static void
 855 check_agent_present(void)
 856 {
 857         if (options.forward_agent) {
 858                 /* Clear agent forwarding if we don't have an agent. */
 859                 if (!ssh_agent_present())
 860                         options.forward_agent = 0;
 861         }
 862 }
 863
 864 static int
 865 ssh_session(void)
 866 {
 867         int type;
 868         int interactive = 0;
 869         int have_tty = 0;
 870         struct winsize ws;
 871         char *cp;
 872         const char *display;
 873
 874         /* Enable compression if requested. */
 875         if (options.compression) {
 876                 debug("Requesting compression at level %d.", options.compression_level);
 877
 878                 if (options.compression_level < 1 || options.compression_level > 9)
 879                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 880
 881                 /* Send the request. */
 882                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 883                 packet_put_int(options.compression_level);
 884                 packet_send();
 885                 packet_write_wait();
 886                 type = packet_read();
 887                 if (type == SSH_SMSG_SUCCESS)
 888                         packet_start_compression(options.compression_level);
 889                 else if (type == SSH_SMSG_FAILURE)
 890                         logit("Warning: Remote host refused compression.");
 891                 else
 892                         packet_disconnect("Protocol error waiting for compression response.");
 893         }
 894         /* Allocate a pseudo tty if appropriate. */
 895         if (tty_flag) {
 896                 debug("Requesting pty.");
 897
 898                 /* Start the packet. */
 899                 packet_start(SSH_CMSG_REQUEST_PTY);
 900
 901                 /* Store TERM in the packet.  There is no limit on the
 902                    length of the string. */
 903                 cp = getenv("TERM");
 904                 if (!cp)
 905                         cp = "";
 906                 packet_put_cstring(cp);
 907
 908                 /* Store window size in the packet. */
 909                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 910                         memset(&ws, 0, sizeof(ws));
 911                 packet_put_int((u_int)ws.ws_row);
 912                 packet_put_int((u_int)ws.ws_col);
 913                 packet_put_int((u_int)ws.ws_xpixel);
 914                 packet_put_int((u_int)ws.ws_ypixel);
 915
 916                 /* Store tty modes in the packet. */
 917                 tty_make_modes(fileno(stdin), NULL);
 918
 919                 /* Send the packet, and wait for it to leave. */
 920                 packet_send();
 921                 packet_write_wait();
 922
 923                 /* Read response from the server. */
 924                 type = packet_read();
 925                 if (type == SSH_SMSG_SUCCESS) {
 926                         interactive = 1;
 927                         have_tty = 1;
 928                 } else if (type == SSH_SMSG_FAILURE)
 929                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 930                 else
 931                         packet_disconnect("Protocol error waiting for pty request response.");
 932         }
 933         /* Request X11 forwarding if enabled and DISPLAY is set. */
 934         display = getenv("DISPLAY");
 935         if (options.forward_x11 && display != NULL) {
 936                 char *proto, *data;
 937                 /* Get reasonable local authentication information. */
 938                 client_x11_get_proto(display, options.xauth_location,
 939                     options.forward_x11_trusted, &proto, &data);
 940                 /* Request forwarding with authentication spoofing. */
 941                 debug("Requesting X11 forwarding with authentication spoofing.");
 942                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 943
 944                 /* Read response from the server. */
 945                 type = packet_read();
 946                 if (type == SSH_SMSG_SUCCESS) {
 947                         interactive = 1;
 948                 } else if (type == SSH_SMSG_FAILURE) {
 949                         logit("Warning: Remote host denied X11 forwarding.");
 950                 } else {
 951                         packet_disconnect("Protocol error waiting for X11 forwarding");
 952                 }
 953         }
 954         /* Tell the packet module whether this is an interactive session. */
 955         packet_set_interactive(interactive);
 956
 957         /* Request authentication agent forwarding if appropriate. */
 958         check_agent_present();
 959
 960         if (options.forward_agent) {
 961                 debug("Requesting authentication agent forwarding.");
 962                 auth_request_forwarding();
 963
 964                 /* Read response from the server. */
 965                 type = packet_read();
 966                 packet_check_eom();
 967                 if (type != SSH_SMSG_SUCCESS)
 968                         logit("Warning: Remote host denied authentication agent forwarding.");
 969         }
 970
 971         /* Initiate port forwardings. */
 972         ssh_init_forwarding();
 973
 974         /* If requested, let ssh continue in the background. */
 975         if (fork_after_authentication_flag)
 976                 if (daemon(1, 1) < 0)
 977                         fatal("daemon() failed: %.200s", strerror(errno));
 978
 979         /*
 980          * If a command was specified on the command line, execute the
 981          * command now. Otherwise request the server to start a shell.
 982          */
 983         if (buffer_len(&command) > 0) {
 984                 int len = buffer_len(&command);
 985                 if (len > 900)
 986                         len = 900;
 987                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 988                 packet_start(SSH_CMSG_EXEC_CMD);
 989                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 990                 packet_send();
 991                 packet_write_wait();
 992         } else {
 993                 debug("Requesting shell.");
 994                 packet_start(SSH_CMSG_EXEC_SHELL);
 995                 packet_send();
 996                 packet_write_wait();
 997         }
 998
 999         /* Enter the interactive session. */
1000         return client_loop(have_tty, tty_flag ?
1001             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1002 }
1003
1004 static void
1005 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1006 {
1007         int id, len;
1008
1009         id = packet_get_int();
1010         len = buffer_len(&command);
1011         if (len > 900)
1012                 len = 900;
1013         packet_check_eom();
1014         if (type == SSH2_MSG_CHANNEL_FAILURE)
1015                 fatal("Request for subsystem '%.*s' failed on channel %d",
1016                     len, (u_char *)buffer_ptr(&command), id);
1017 }
1018
1019 void
1020 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1021 {
1022         int i;
1023
1024         i = client_global_request_id++;
1025         if (i >= options.num_remote_forwards)
1026                 return;
1027         debug("remote forward %s for: listen %d, connect %s:%d",
1028             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1029             options.remote_forwards[i].listen_port,
1030             options.remote_forwards[i].connect_host,
1031             options.remote_forwards[i].connect_port);
1032         if (type == SSH2_MSG_REQUEST_FAILURE) {
1033                 if (options.exit_on_forward_failure)
1034                         fatal("Error: remote port forwarding failed for "
1035                             "listen port %d",
1036                             options.remote_forwards[i].listen_port);
1037                 else
1038                         logit("Warning: remote port forwarding failed for "
1039                             "listen port %d",
1040                             options.remote_forwards[i].listen_port);
1041         }
1042 }
1043
1044 static void
1045 ssh_control_listener(void)
1046 {
1047         struct sockaddr_un addr;
1048         mode_t old_umask;
1049         int addr_len;
1050
1051         if (options.control_path == NULL ||
1052             options.control_master == SSHCTL_MASTER_NO)
1053                 return;
1054
1055         debug("setting up multiplex master socket");
1056
1057         memset(&addr, '\0', sizeof(addr));
1058         addr.sun_family = AF_UNIX;
1059         addr_len = offsetof(struct sockaddr_un, sun_path) +
1060             strlen(options.control_path) + 1;
1061
1062         if (strlcpy(addr.sun_path, options.control_path,
1063             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1064                 fatal("ControlPath too long");
1065
1066         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1067                 fatal("%s socket(): %s", __func__, strerror(errno));
1068
1069         old_umask = umask(0177);
1070         if (bind(control_fd, (struct sockaddr *)&addr, addr_len) == -1) {
1071                 control_fd = -1;
1072                 if (errno == EINVAL || errno == EADDRINUSE)
1073                         fatal("ControlSocket %s already exists",
1074                             options.control_path);
1075                 else
1076                         fatal("%s bind(): %s", __func__, strerror(errno));
1077         }
1078         umask(old_umask);
1079
1080         if (listen(control_fd, 64) == -1)
1081                 fatal("%s listen(): %s", __func__, strerror(errno));
1082
1083         set_nonblock(control_fd);
1084 }
1085
1086 /* request pty/x11/agent/tcpfwd/shell for channel */
1087 static void
1088 ssh_session2_setup(int id, void *arg)
1089 {
1090         extern char **environ;
1091         const char *display;
1092         int interactive = tty_flag;
1093
1094         display = getenv("DISPLAY");
1095         if (options.forward_x11 && display != NULL) {
1096                 char *proto, *data;
1097                 /* Get reasonable local authentication information. */
1098                 client_x11_get_proto(display, options.xauth_location,
1099                     options.forward_x11_trusted, &proto, &data);
1100                 /* Request forwarding with authentication spoofing. */
1101                 debug("Requesting X11 forwarding with authentication spoofing.");
1102                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1103                 interactive = 1;
1104                 /* XXX wait for reply */
1105         }
1106
1107         check_agent_present();
1108         if (options.forward_agent) {
1109                 debug("Requesting authentication agent forwarding.");
1110                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1111                 packet_send();
1112         }
1113
1114         if (options.tun_open != SSH_TUNMODE_NO) {
1115                 Channel *c;
1116                 int fd;
1117
1118                 debug("Requesting tun.");
1119                 if ((fd = tun_open(options.tun_local,
1120                     options.tun_open)) >= 0) {
1121                         c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1122                             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1123                             0, "tun", 1);
1124                         c->datagram = 1;
1125 #if defined(SSH_TUN_FILTER)
1126                         if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
1127                                 channel_register_filter(c->self, sys_tun_infilter,
1128                                     sys_tun_outfilter);
1129 #endif
1130                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1131                         packet_put_cstring("tun@openssh.com");
1132                         packet_put_int(c->self);
1133                         packet_put_int(c->local_window_max);
1134                         packet_put_int(c->local_maxpacket);
1135                         packet_put_int(options.tun_open);
1136                         packet_put_int(options.tun_remote);
1137                         packet_send();
1138                 }
1139         }
1140
1141         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1142             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1143
1144         packet_set_interactive(interactive);
1145 }
1146
1147 /* open new channel for a session */
1148 static int
1149 ssh_session2_open(void)
1150 {
1151         Channel *c;
1152         int window, packetmax, in, out, err;
1153
1154         if (stdin_null_flag) {
1155                 in = open(_PATH_DEVNULL, O_RDONLY);
1156         } else {
1157                 in = dup(STDIN_FILENO);
1158         }
1159         out = dup(STDOUT_FILENO);
1160         err = dup(STDERR_FILENO);
1161
1162         if (in < 0 || out < 0 || err < 0)
1163                 fatal("dup() in/out/err failed");
1164
1165         /* enable nonblocking unless tty */
1166         if (!isatty(in))
1167                 set_nonblock(in);
1168         if (!isatty(out))
1169                 set_nonblock(out);
1170         if (!isatty(err))
1171                 set_nonblock(err);
1172
1173         window = CHAN_SES_WINDOW_DEFAULT;
1174         packetmax = CHAN_SES_PACKET_DEFAULT;
1175         if (tty_flag) {
1176                 window >>= 1;
1177                 packetmax >>= 1;
1178         }
1179         c = channel_new(
1180             "session", SSH_CHANNEL_OPENING, in, out, err,
1181             window, packetmax, CHAN_EXTENDED_WRITE,
1182             "client-session", /*nonblock*/0);
1183
1184         debug3("ssh_session2_open: channel_new: %d", c->self);
1185
1186         channel_send_open(c->self);
1187         if (!no_shell_flag)
1188                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1189
1190         return c->self;
1191 }
1192
1193 static int
1194 ssh_session2(void)
1195 {
1196         int id = -1;
1197
1198         /* XXX should be pre-session */
1199         ssh_init_forwarding();
1200         ssh_control_listener();
1201
1202         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1203                 id = ssh_session2_open();
1204
1205         /* Execute a local command */
1206         if (options.local_command != NULL &&
1207             options.permit_local_command)
1208                 ssh_local_cmd(options.local_command);
1209
1210         /* If requested, let ssh continue in the background. */
1211         if (fork_after_authentication_flag)
1212                 if (daemon(1, 1) < 0)
1213                         fatal("daemon() failed: %.200s", strerror(errno));
1214
1215         return client_loop(tty_flag, tty_flag ?
1216             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1217 }
1218
1219 static void
1220 load_public_identity_files(void)
1221 {
1222         char *filename, *cp, thishost[NI_MAXHOST];
1223         int i = 0;
1224         Key *public;
1225         struct passwd *pw;
1226 #ifdef SMARTCARD
1227         Key **keys;
1228
1229         if (options.smartcard_device != NULL &&
1230             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1231             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1232                 int count = 0;
1233                 for (i = 0; keys[i] != NULL; i++) {
1234                         count++;
1235                         memmove(&options.identity_files[1], &options.identity_files[0],
1236                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1237                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1238                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1239                         options.num_identity_files++;
1240                         options.identity_keys[0] = keys[i];
1241                         options.identity_files[0] = sc_get_key_label(keys[i]);
1242                 }
1243                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1244                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1245                 i = count;
1246                 xfree(keys);
1247         }
1248 #endif /* SMARTCARD */
1249         if ((pw = getpwuid(original_real_uid)) == NULL)
1250                 fatal("load_public_identity_files: getpwuid failed");
1251         if (gethostname(thishost, sizeof(thishost)) == -1)
1252                 fatal("load_public_identity_files: gethostname: %s",
1253                     strerror(errno));
1254         for (; i < options.num_identity_files; i++) {
1255                 cp = tilde_expand_filename(options.identity_files[i],
1256                     original_real_uid);
1257                 filename = percent_expand(cp, "d", pw->pw_dir,
1258                     "u", pw->pw_name, "l", thishost, "h", host,
1259                     "r", options.user, (char *)NULL);
1260                 xfree(cp);
1261                 public = key_load_public(filename, NULL);
1262                 debug("identity file %s type %d", filename,
1263                     public ? public->type : -1);
1264                 xfree(options.identity_files[i]);
1265                 options.identity_files[i] = filename;
1266                 options.identity_keys[i] = public;
1267         }
1268 }
1269
1270 static void
1271 control_client_sighandler(int signo)
1272 {
1273         control_client_terminate = signo;
1274 }
1275
1276 static void
1277 control_client_sigrelay(int signo)
1278 {
1279         if (control_server_pid > 1)
1280                 kill(control_server_pid, signo);
1281 }
1282
1283 static int
1284 env_permitted(char *env)
1285 {
1286         int i, ret;
1287         char name[1024], *cp;
1288
1289         if ((cp = strchr(env, '=')) == NULL || cp == env)
1290                 return (0);
1291         ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
1292         if (ret <= 0 || (size_t)ret >= sizeof(name))
1293                 fatal("env_permitted: name '%.100s...' too long", env);
1294
1295         for (i = 0; i < options.num_send_env; i++)
1296                 if (match_pattern(name, options.send_env[i]))
1297                         return (1);
1298
1299         return (0);
1300 }
1301
1302 static void
1303 control_client(const char *path)
1304 {
1305         struct sockaddr_un addr;
1306         int i, r, fd, sock, exitval, num_env, addr_len;
1307         Buffer m;
1308         char *term;
1309         extern char **environ;
1310         u_int  flags;
1311
1312         if (mux_command == 0)
1313                 mux_command = SSHMUX_COMMAND_OPEN;
1314
1315         switch (options.control_master) {
1316         case SSHCTL_MASTER_AUTO:
1317         case SSHCTL_MASTER_AUTO_ASK:
1318                 debug("auto-mux: Trying existing master");
1319                 /* FALLTHROUGH */
1320         case SSHCTL_MASTER_NO:
1321                 break;
1322         default:
1323                 return;
1324         }
1325
1326         memset(&addr, '\0', sizeof(addr));
1327         addr.sun_family = AF_UNIX;
1328         addr_len = offsetof(struct sockaddr_un, sun_path) +
1329             strlen(path) + 1;
1330
1331         if (strlcpy(addr.sun_path, path,
1332             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1333                 fatal("ControlPath too long");
1334
1335         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1336                 fatal("%s socket(): %s", __func__, strerror(errno));
1337
1338         if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) {
1339                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1340                         fatal("Control socket connect(%.100s): %s", path,
1341                             strerror(errno));
1342                 }
1343                 if (errno == ENOENT)
1344                         debug("Control socket \"%.100s\" does not exist", path);
1345                 else {
1346                         error("Control socket connect(%.100s): %s", path,
1347                             strerror(errno));
1348                 }
1349                 close(sock);
1350                 return;
1351         }
1352
1353         if (stdin_null_flag) {
1354                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1355                         fatal("open(/dev/null): %s", strerror(errno));
1356                 if (dup2(fd, STDIN_FILENO) == -1)
1357                         fatal("dup2: %s", strerror(errno));
1358                 if (fd > STDERR_FILENO)
1359                         close(fd);
1360         }
1361
1362         term = getenv("TERM");
1363
1364         flags = 0;
1365         if (tty_flag)
1366                 flags |= SSHMUX_FLAG_TTY;
1367         if (subsystem_flag)
1368                 flags |= SSHMUX_FLAG_SUBSYS;
1369         if (options.forward_x11)
1370                 flags |= SSHMUX_FLAG_X11_FWD;
1371         if (options.forward_agent)
1372                 flags |= SSHMUX_FLAG_AGENT_FWD;
1373
1374         buffer_init(&m);
1375
1376         /* Send our command to server */
1377         buffer_put_int(&m, mux_command);
1378         buffer_put_int(&m, flags);
1379         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1380                 fatal("%s: msg_send", __func__);
1381         buffer_clear(&m);
1382
1383         /* Get authorisation status and PID of controlee */
1384         if (ssh_msg_recv(sock, &m) == -1)
1385                 fatal("%s: msg_recv", __func__);
1386         if (buffer_get_char(&m) != SSHMUX_VER)
1387                 fatal("%s: wrong version", __func__);
1388         if (buffer_get_int(&m) != 1)
1389                 fatal("Connection to master denied");
1390         control_server_pid = buffer_get_int(&m);
1391
1392         buffer_clear(&m);
1393
1394         switch (mux_command) {
1395         case SSHMUX_COMMAND_ALIVE_CHECK:
1396                 fprintf(stderr, "Master running (pid=%d)\r\n",
1397                     control_server_pid);
1398                 exit(0);
1399         case SSHMUX_COMMAND_TERMINATE:
1400                 fprintf(stderr, "Exit request sent.\r\n");
1401                 exit(0);
1402         case SSHMUX_COMMAND_OPEN:
1403                 /* continue below */
1404                 break;
1405         default:
1406                 fatal("silly mux_command %d", mux_command);
1407         }
1408
1409         /* SSHMUX_COMMAND_OPEN */
1410         buffer_put_cstring(&m, term ? term : "");
1411         buffer_append(&command, "\0", 1);
1412         buffer_put_cstring(&m, buffer_ptr(&command));
1413
1414         if (options.num_send_env == 0 || environ == NULL) {
1415                 buffer_put_int(&m, 0);
1416         } else {
1417                 /* Pass environment */
1418                 num_env = 0;
1419                 for (i = 0; environ[i] != NULL; i++)
1420                         if (env_permitted(environ[i]))
1421                                 num_env++; /* Count */
1422
1423                 buffer_put_int(&m, num_env);
1424
1425                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1426                         if (env_permitted(environ[i])) {
1427                                 num_env--;
1428                                 buffer_put_cstring(&m, environ[i]);
1429                         }
1430         }
1431
1432         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1433                 fatal("%s: msg_send", __func__);
1434
1435         mm_send_fd(sock, STDIN_FILENO);
1436         mm_send_fd(sock, STDOUT_FILENO);
1437         mm_send_fd(sock, STDERR_FILENO);
1438
1439         /* Wait for reply, so master has a chance to gather ttymodes */
1440         buffer_clear(&m);
1441         if (ssh_msg_recv(sock, &m) == -1)
1442                 fatal("%s: msg_recv", __func__);
1443         if (buffer_get_char(&m) != SSHMUX_VER)
1444                 fatal("%s: wrong version", __func__);
1445         buffer_free(&m);
1446
1447         signal(SIGHUP, control_client_sighandler);
1448         signal(SIGINT, control_client_sighandler);
1449         signal(SIGTERM, control_client_sighandler);
1450         signal(SIGWINCH, control_client_sigrelay);
1451
1452         if (tty_flag)
1453                 enter_raw_mode();
1454
1455         /* Stick around until the controlee closes the client_fd */
1456         exitval = 0;
1457         for (;!control_client_terminate;) {
1458                 r = read(sock, &exitval, sizeof(exitval));
1459                 if (r == 0) {
1460                         debug2("Received EOF from master");
1461                         break;
1462                 }
1463                 if (r > 0)
1464                         debug2("Received exit status from master %d", exitval);
1465                 if (r == -1 && errno != EINTR)
1466                         fatal("%s: read %s", __func__, strerror(errno));
1467         }
1468
1469         if (control_client_terminate)
1470                 debug2("Exiting on signal %d", control_client_terminate);
1471
1472         close(sock);
1473
1474         leave_raw_mode();
1475
1476         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1477                 fprintf(stderr, "Connection to master closed.\r\n");
1478
1479         exit(exitval);
1480 }