crypto/openssh-5/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.309 2008/01/19 20:51:26 djm 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 <stdarg.h>
  64 #include <stddef.h>
  65 #include <stdio.h>
  66 #include <stdlib.h>
  67 #include <string.h>
  68 #include <unistd.h>
  69
  70 #include <netinet/in.h>
  71 #include <arpa/inet.h>
  72
  73 #include <openssl/evp.h>
  74 #include <openssl/err.h>
  75 #include "openbsd-compat/openssl-compat.h"
  76
  77 #include "xmalloc.h"
  78 #include "ssh.h"
  79 #include "ssh1.h"
  80 #include "ssh2.h"
  81 #include "compat.h"
  82 #include "cipher.h"
  83 #include "packet.h"
  84 #include "buffer.h"
  85 #include "channels.h"
  86 #include "key.h"
  87 #include "authfd.h"
  88 #include "authfile.h"
  89 #include "pathnames.h"
  90 #include "dispatch.h"
  91 #include "clientloop.h"
  92 #include "log.h"
  93 #include "readconf.h"
  94 #include "sshconnect.h"
  95 #include "misc.h"
  96 #include "kex.h"
  97 #include "mac.h"
  98 #include "sshpty.h"
  99 #include "match.h"
 100 #include "msg.h"
 101 #include "monitor_fdpass.h"
 102 #include "uidswap.h"
 103 #include "version.h"
 104
 105 #ifdef SMARTCARD
 106 #include "scard.h"
 107 #endif
 108
 109 extern char *__progname;
 110
 111 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
 112 int debug_flag = 0;
 113
 114 /* Flag indicating whether a tty should be allocated */
 115 int tty_flag = 0;
 116 int no_tty_flag = 0;
 117 int force_tty_flag = 0;
 118
 119 /* don't exec a shell */
 120 int no_shell_flag = 0;
 121
 122 /*
 123  * Flag indicating that nothing should be read from stdin.  This can be set
 124  * on the command line.
 125  */
 126 int stdin_null_flag = 0;
 127
 128 /*
 129  * Flag indicating that ssh should fork after authentication.  This is useful
 130  * so that the passphrase can be entered manually, and then ssh goes to the
 131  * background.
 132  */
 133 int fork_after_authentication_flag = 0;
 134
 135 /*
 136  * General data structure for command line options and options configurable
 137  * in configuration files.  See readconf.h.
 138  */
 139 Options options;
 140
 141 /* optional user configfile */
 142 char *config = NULL;
 143
 144 /*
 145  * Name of the host we are connecting to.  This is the name given on the
 146  * command line, or the HostName specified for the user-supplied name in a
 147  * configuration file.
 148  */
 149 char *host;
 150
 151 /* socket address the host resolves to */
 152 struct sockaddr_storage hostaddr;
 153
 154 /* Private host keys. */
 155 Sensitive sensitive_data;
 156
 157 /* Original real UID. */
 158 uid_t original_real_uid;
 159 uid_t original_effective_uid;
 160
 161 /* command to be executed */
 162 Buffer command;
 163
 164 /* Should we execute a command or invoke a subsystem? */
 165 int subsystem_flag = 0;
 166
 167 /* # of replies received for global requests */
 168 static int client_global_request_id = 0;
 169
 170 /* pid of proxycommand child process */
 171 pid_t proxy_command_pid = 0;
 172
 173 /* fd to control socket */
 174 int control_fd = -1;
 175
 176 /* Multiplexing control command */
 177 static u_int mux_command = 0;
 178
 179 /* Only used in control client mode */
 180 volatile sig_atomic_t control_client_terminate = 0;
 181 u_int control_server_pid = 0;
 182
 183 /* Prints a help message to the user.  This function never returns. */
 184
 185 static void
 186 usage(void)
 187 {
 188         fprintf(stderr,
 189 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 190 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 191 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 192 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 193 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 194 "           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
 195         );
 196         exit(255);
 197 }
 198
 199 static int ssh_session(void);
 200 static int ssh_session2(void);
 201 static void load_public_identity_files(void);
 202 static void control_client(const char *path);
 203
 204 /*
 205  * Main program for the ssh client.
 206  */
 207 int
 208 main(int ac, char **av)
 209 {
 210         int i, opt, exit_status;
 211         char *p, *cp, *line, buf[256];
 212         struct stat st;
 213         struct passwd *pw;
 214         int dummy, timeout_ms;
 215         extern int optind, optreset;
 216         extern char *optarg;
 217         struct servent *sp;
 218         Forward fwd;
 219
 220         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 221         sanitise_stdfd();
 222
 223         __progname = ssh_get_progname(av[0]);
 224         init_rng();
 225
 226         /*
 227          * Save the original real uid.  It will be needed later (uid-swapping
 228          * may clobber the real uid).
 229          */
 230         original_real_uid = getuid();
 231         original_effective_uid = geteuid();
 232
 233         /*
 234          * Use uid-swapping to give up root privileges for the duration of
 235          * option processing.  We will re-instantiate the rights when we are
 236          * ready to create the privileged port, and will permanently drop
 237          * them when the port has been created (actually, when the connection
 238          * has been made, as we may need to create the port several times).
 239          */
 240         PRIV_END;
 241
 242 #ifdef HAVE_SETRLIMIT
 243         /* If we are installed setuid root be careful to not drop core. */
 244         if (original_real_uid != original_effective_uid) {
 245                 struct rlimit rlim;
 246                 rlim.rlim_cur = rlim.rlim_max = 0;
 247                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 248                         fatal("setrlimit failed: %.100s", strerror(errno));
 249         }
 250 #endif
 251         /* Get user data. */
 252         pw = getpwuid(original_real_uid);
 253         if (!pw) {
 254                 logit("You don't exist, go away!");
 255                 exit(255);
 256         }
 257         /* Take a copy of the returned structure. */
 258         pw = pwcopy(pw);
 259
 260         /*
 261          * Set our umask to something reasonable, as some files are created
 262          * with the default umask.  This will make them world-readable but
 263          * writable only by the owner, which is ok for all files for which we
 264          * don't set the modes explicitly.
 265          */
 266         umask(022);
 267
 268         /* Initialize option structure to indicate that no values have been set. */
 269         initialize_options(&options);
 270
 271         /* Parse command-line arguments. */
 272         host = NULL;
 273
 274  again:
 275         while ((opt = getopt(ac, av,
 276             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:KL:MNO:PR:S:TVw:XY")) != -1) {
 277                 switch (opt) {
 278                 case '1':
 279                         options.protocol = SSH_PROTO_1;
 280                         break;
 281                 case '2':
 282                         options.protocol = SSH_PROTO_2;
 283                         break;
 284                 case '4':
 285                         options.address_family = AF_INET;
 286                         break;
 287                 case '6':
 288                         options.address_family = AF_INET6;
 289                         break;
 290                 case 'n':
 291                         stdin_null_flag = 1;
 292                         break;
 293                 case 'f':
 294                         fork_after_authentication_flag = 1;
 295                         stdin_null_flag = 1;
 296                         break;
 297                 case 'x':
 298                         options.forward_x11 = 0;
 299                         break;
 300                 case 'X':
 301                         options.forward_x11 = 1;
 302                         break;
 303                 case 'Y':
 304                         options.forward_x11 = 1;
 305                         options.forward_x11_trusted = 1;
 306                         break;
 307                 case 'g':
 308                         options.gateway_ports = 1;
 309                         break;
 310                 case 'O':
 311                         if (strcmp(optarg, "check") == 0)
 312                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 313                         else if (strcmp(optarg, "exit") == 0)
 314                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 315                         else
 316                                 fatal("Invalid multiplex command.");
 317                         break;
 318                 case 'P':       /* deprecated */
 319                         options.use_privileged_port = 0;
 320                         break;
 321                 case 'a':
 322                         options.forward_agent = 0;
 323                         break;
 324                 case 'A':
 325                         options.forward_agent = 1;
 326                         break;
 327                 case 'k':
 328                         options.gss_deleg_creds = 0;
 329                         break;
 330                 case 'K':
 331                         options.gss_authentication = 1;
 332                         options.gss_deleg_creds = 1;
 333                         break;
 334                 case 'i':
 335                         if (stat(optarg, &st) < 0) {
 336                                 fprintf(stderr, "Warning: Identity file %s "
 337                                     "not accessible: %s.\n", optarg,
 338                                     strerror(errno));
 339                                 break;
 340                         }
 341                         if (options.num_identity_files >=
 342                             SSH_MAX_IDENTITY_FILES)
 343                                 fatal("Too many identity files specified "
 344                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 345                         options.identity_files[options.num_identity_files++] =
 346                             xstrdup(optarg);
 347                         break;
 348                 case 'I':
 349 #ifdef SMARTCARD
 350                         options.smartcard_device = xstrdup(optarg);
 351 #else
 352                         fprintf(stderr, "no support for smartcards.\n");
 353 #endif
 354                         break;
 355                 case 't':
 356                         if (tty_flag)
 357                                 force_tty_flag = 1;
 358                         tty_flag = 1;
 359                         break;
 360                 case 'v':
 361                         if (debug_flag == 0) {
 362                                 debug_flag = 1;
 363                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 364                         } else {
 365                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 366                                         options.log_level++;
 367                                 break;
 368                         }
 369                         /* FALLTHROUGH */
 370                 case 'V':
 371                         fprintf(stderr, "%s, %s\n",
 372                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 373                         if (opt == 'V')
 374                                 exit(0);
 375                         break;
 376                 case 'w':
 377                         if (options.tun_open == -1)
 378                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 379                         options.tun_local = a2tun(optarg, &options.tun_remote);
 380                         if (options.tun_local == SSH_TUNID_ERR) {
 381                                 fprintf(stderr, "Bad tun device '%s'\n", optarg);
 382                                 exit(255);
 383                         }
 384                         break;
 385                 case 'q':
 386                         options.log_level = SYSLOG_LEVEL_QUIET;
 387                         break;
 388                 case 'e':
 389                         if (optarg[0] == '^' && optarg[2] == 0 &&
 390                             (u_char) optarg[1] >= 64 &&
 391                             (u_char) optarg[1] < 128)
 392                                 options.escape_char = (u_char) optarg[1] & 31;
 393                         else if (strlen(optarg) == 1)
 394                                 options.escape_char = (u_char) optarg[0];
 395                         else if (strcmp(optarg, "none") == 0)
 396                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 397                         else {
 398                                 fprintf(stderr, "Bad escape character '%s'.\n",
 399                                     optarg);
 400                                 exit(255);
 401                         }
 402                         break;
 403                 case 'c':
 404                         if (ciphers_valid(optarg)) {
 405                                 /* SSH2 only */
 406                                 options.ciphers = xstrdup(optarg);
 407                                 options.cipher = SSH_CIPHER_INVALID;
 408                         } else {
 409                                 /* SSH1 only */
 410                                 options.cipher = cipher_number(optarg);
 411                                 if (options.cipher == -1) {
 412                                         fprintf(stderr,
 413                                             "Unknown cipher type '%s'\n",
 414                                             optarg);
 415                                         exit(255);
 416                                 }
 417                                 if (options.cipher == SSH_CIPHER_3DES)
 418                                         options.ciphers = "3des-cbc";
 419                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 420                                         options.ciphers = "blowfish-cbc";
 421                                 else
 422                                         options.ciphers = (char *)-1;
 423                         }
 424                         break;
 425                 case 'm':
 426                         if (mac_valid(optarg))
 427                                 options.macs = xstrdup(optarg);
 428                         else {
 429                                 fprintf(stderr, "Unknown mac type '%s'\n",
 430                                     optarg);
 431                                 exit(255);
 432                         }
 433                         break;
 434                 case 'M':
 435                         if (options.control_master == SSHCTL_MASTER_YES)
 436                                 options.control_master = SSHCTL_MASTER_ASK;
 437                         else
 438                                 options.control_master = SSHCTL_MASTER_YES;
 439                         break;
 440                 case 'p':
 441                         options.port = a2port(optarg);
 442                         if (options.port == 0) {
 443                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 444                                 exit(255);
 445                         }
 446                         break;
 447                 case 'l':
 448                         options.user = optarg;
 449                         break;
 450
 451                 case 'L':
 452                         if (parse_forward(&fwd, optarg))
 453                                 add_local_forward(&options, &fwd);
 454                         else {
 455                                 fprintf(stderr,
 456                                     "Bad local forwarding specification '%s'\n",
 457                                     optarg);
 458                                 exit(255);
 459                         }
 460                         break;
 461
 462                 case 'R':
 463                         if (parse_forward(&fwd, optarg)) {
 464                                 add_remote_forward(&options, &fwd);
 465                         } else {
 466                                 fprintf(stderr,
 467                                     "Bad remote forwarding specification "
 468                                     "'%s'\n", optarg);
 469                                 exit(255);
 470                         }
 471                         break;
 472
 473                 case 'D':
 474                         cp = p = xstrdup(optarg);
 475                         memset(&fwd, '\0', sizeof(fwd));
 476                         fwd.connect_host = "socks";
 477                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 478                                 fprintf(stderr, "Bad dynamic forwarding "
 479                                     "specification '%.100s'\n", optarg);
 480                                 exit(255);
 481                         }
 482                         if (cp != NULL) {
 483                                 fwd.listen_port = a2port(cp);
 484                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 485                         } else {
 486                                 fwd.listen_port = a2port(fwd.listen_host);
 487                                 fwd.listen_host = NULL;
 488                         }
 489
 490                         if (fwd.listen_port == 0) {
 491                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 492                                     optarg);
 493                                 exit(255);
 494                         }
 495                         add_local_forward(&options, &fwd);
 496                         xfree(p);
 497                         break;
 498
 499                 case 'C':
 500                         options.compression = 1;
 501                         break;
 502                 case 'N':
 503                         no_shell_flag = 1;
 504                         no_tty_flag = 1;
 505                         break;
 506                 case 'T':
 507                         no_tty_flag = 1;
 508                         break;
 509                 case 'o':
 510                         dummy = 1;
 511                         line = xstrdup(optarg);
 512                         if (process_config_line(&options, host ? host : "",
 513                             line, "command-line", 0, &dummy) != 0)
 514                                 exit(255);
 515                         xfree(line);
 516                         break;
 517                 case 's':
 518                         subsystem_flag = 1;
 519                         break;
 520                 case 'S':
 521                         if (options.control_path != NULL)
 522                                 free(options.control_path);
 523                         options.control_path = xstrdup(optarg);
 524                         break;
 525                 case 'b':
 526                         options.bind_address = optarg;
 527                         break;
 528                 case 'F':
 529                         config = optarg;
 530                         break;
 531                 default:
 532                         usage();
 533                 }
 534         }
 535
 536         ac -= optind;
 537         av += optind;
 538
 539         if (ac > 0 && !host && **av != '-') {
 540                 if (strrchr(*av, '@')) {
 541                         p = xstrdup(*av);
 542                         cp = strrchr(p, '@');
 543                         if (cp == NULL || cp == p)
 544                                 usage();
 545                         options.user = p;
 546                         *cp = '\0';
 547                         host = ++cp;
 548                 } else
 549                         host = *av;
 550                 if (ac > 1) {
 551                         optind = optreset = 1;
 552                         goto again;
 553                 }
 554                 ac--, av++;
 555         }
 556
 557         /* Check that we got a host name. */
 558         if (!host)
 559                 usage();
 560
 561         SSLeay_add_all_algorithms();
 562         ERR_load_crypto_strings();
 563
 564         /* Initialize the command to execute on remote host. */
 565         buffer_init(&command);
 566
 567         /*
 568          * Save the command to execute on the remote host in a buffer. There
 569          * is no limit on the length of the command, except by the maximum
 570          * packet size.  Also sets the tty flag if there is no command.
 571          */
 572         if (!ac) {
 573                 /* No command specified - execute shell on a tty. */
 574                 tty_flag = 1;
 575                 if (subsystem_flag) {
 576                         fprintf(stderr,
 577                             "You must specify a subsystem to invoke.\n");
 578                         usage();
 579                 }
 580         } else {
 581                 /* A command has been specified.  Store it into the buffer. */
 582                 for (i = 0; i < ac; i++) {
 583                         if (i)
 584                                 buffer_append(&command, " ", 1);
 585                         buffer_append(&command, av[i], strlen(av[i]));
 586                 }
 587         }
 588
 589         /* Cannot fork to background if no command. */
 590         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 591                 fatal("Cannot fork into background without a command to execute.");
 592
 593         /* Allocate a tty by default if no command specified. */
 594         if (buffer_len(&command) == 0)
 595                 tty_flag = 1;
 596
 597         /* Force no tty */
 598         if (no_tty_flag)
 599                 tty_flag = 0;
 600         /* Do not allocate a tty if stdin is not a tty. */
 601         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 602                 if (tty_flag)
 603                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 604                 tty_flag = 0;
 605         }
 606
 607         /*
 608          * Initialize "log" output.  Since we are the client all output
 609          * actually goes to stderr.
 610          */
 611         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 612             SYSLOG_FACILITY_USER, 1);
 613
 614         /*
 615          * Read per-user configuration file.  Ignore the system wide config
 616          * file if the user specifies a config file on the command line.
 617          */
 618         if (config != NULL) {
 619                 if (!read_config_file(config, host, &options, 0))
 620                         fatal("Can't open user config file %.100s: "
 621                             "%.100s", config, strerror(errno));
 622         } else {
 623                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 624                     _PATH_SSH_USER_CONFFILE);
 625                 (void)read_config_file(buf, host, &options, 1);
 626
 627                 /* Read systemwide configuration file after use config. */
 628                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 629                     &options, 0);
 630         }
 631
 632         /* Fill configuration defaults. */
 633         fill_default_options(&options);
 634
 635         channel_set_af(options.address_family);
 636
 637         /* reinit */
 638         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 639
 640         seed_rng();
 641
 642         if (options.user == NULL)
 643                 options.user = xstrdup(pw->pw_name);
 644
 645         if (options.hostname != NULL)
 646                 host = options.hostname;
 647
 648         /* Find canonic host name. */
 649         if (strchr(host, '.') == 0) {
 650                 struct addrinfo hints;
 651                 struct addrinfo *ai = NULL;
 652                 int errgai;
 653                 memset(&hints, 0, sizeof(hints));
 654                 hints.ai_family = options.address_family;
 655                 hints.ai_flags = AI_CANONNAME;
 656                 hints.ai_socktype = SOCK_STREAM;
 657                 errgai = getaddrinfo(host, NULL, &hints, &ai);
 658                 if (errgai == 0) {
 659                         if (ai->ai_canonname != NULL)
 660                                 host = xstrdup(ai->ai_canonname);
 661                         freeaddrinfo(ai);
 662                 }
 663         }
 664
 665         /* force lowercase for hostkey matching */
 666         if (options.host_key_alias != NULL) {
 667                 for (p = options.host_key_alias; *p; p++)
 668                         if (isupper(*p))
 669                                 *p = (char)tolower(*p);
 670         }
 671
 672         /* Get default port if port has not been set. */
 673         if (options.port == 0) {
 674                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 675                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 676         }
 677
 678         if (options.proxy_command != NULL &&
 679             strcmp(options.proxy_command, "none") == 0) {
 680                 xfree(options.proxy_command);
 681                 options.proxy_command = NULL;
 682         }
 683         if (options.control_path != NULL &&
 684             strcmp(options.control_path, "none") == 0) {
 685                 xfree(options.control_path);
 686                 options.control_path = NULL;
 687         }
 688
 689         if (options.control_path != NULL) {
 690                 char thishost[NI_MAXHOST];
 691
 692                 if (gethostname(thishost, sizeof(thishost)) == -1)
 693                         fatal("gethostname: %s", strerror(errno));
 694                 snprintf(buf, sizeof(buf), "%d", options.port);
 695                 cp = tilde_expand_filename(options.control_path,
 696                     original_real_uid);
 697                 xfree(options.control_path);
 698                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 699                     "r", options.user, "l", thishost, (char *)NULL);
 700                 xfree(cp);
 701         }
 702         if (mux_command != 0 && options.control_path == NULL)
 703                 fatal("No ControlPath specified for \"-O\" command");
 704         if (options.control_path != NULL)
 705                 control_client(options.control_path);
 706
 707         timeout_ms = options.connection_timeout * 1000;
 708
 709         /* Open a connection to the remote host. */
 710         if (ssh_connect(host, &hostaddr, options.port,
 711             options.address_family, options.connection_attempts, &timeout_ms,
 712             options.tcp_keep_alive,
 713 #ifdef HAVE_CYGWIN
 714             options.use_privileged_port,
 715 #else
 716             original_effective_uid == 0 && options.use_privileged_port,
 717 #endif
 718             options.proxy_command) != 0)
 719                 exit(255);
 720
 721         if (timeout_ms > 0)
 722                 debug3("timeout: %d ms remain after connect", timeout_ms);
 723
 724         /*
 725          * If we successfully made the connection, load the host private key
 726          * in case we will need it later for combined rsa-rhosts
 727          * authentication. This must be done before releasing extra
 728          * privileges, because the file is only readable by root.
 729          * If we cannot access the private keys, load the public keys
 730          * instead and try to execute the ssh-keysign helper instead.
 731          */
 732         sensitive_data.nkeys = 0;
 733         sensitive_data.keys = NULL;
 734         sensitive_data.external_keysign = 0;
 735         if (options.rhosts_rsa_authentication ||
 736             options.hostbased_authentication) {
 737                 sensitive_data.nkeys = 3;
 738                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 739                     sizeof(Key));
 740
 741                 PRIV_START;
 742                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 743                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 744                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 745                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 746                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 747                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 748                 PRIV_END;
 749
 750                 if (options.hostbased_authentication == 1 &&
 751                     sensitive_data.keys[0] == NULL &&
 752                     sensitive_data.keys[1] == NULL &&
 753                     sensitive_data.keys[2] == NULL) {
 754                         sensitive_data.keys[1] = key_load_public(
 755                             _PATH_HOST_DSA_KEY_FILE, NULL);
 756                         sensitive_data.keys[2] = key_load_public(
 757                             _PATH_HOST_RSA_KEY_FILE, NULL);
 758                         sensitive_data.external_keysign = 1;
 759                 }
 760         }
 761         /*
 762          * Get rid of any extra privileges that we may have.  We will no
 763          * longer need them.  Also, extra privileges could make it very hard
 764          * to read identity files and other non-world-readable files from the
 765          * user's home directory if it happens to be on a NFS volume where
 766          * root is mapped to nobody.
 767          */
 768         if (original_effective_uid == 0) {
 769                 PRIV_START;
 770                 permanently_set_uid(pw);
 771         }
 772
 773         /*
 774          * Now that we are back to our own permissions, create ~/.ssh
 775          * directory if it doesn't already exist.
 776          */
 777         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 778         if (stat(buf, &st) < 0)
 779                 if (mkdir(buf, 0700) < 0)
 780                         error("Could not create directory '%.200s'.", buf);
 781
 782         /* load options.identity_files */
 783         load_public_identity_files();
 784
 785         /* Expand ~ in known host file names. */
 786         /* XXX mem-leaks: */
 787         options.system_hostfile =
 788             tilde_expand_filename(options.system_hostfile, original_real_uid);
 789         options.user_hostfile =
 790             tilde_expand_filename(options.user_hostfile, original_real_uid);
 791         options.system_hostfile2 =
 792             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 793         options.user_hostfile2 =
 794             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 795
 796         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 797
 798         /* Log into the remote system.  This never returns if the login fails. */
 799         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 800             pw, timeout_ms);
 801
 802         /* We no longer need the private host keys.  Clear them now. */
 803         if (sensitive_data.nkeys != 0) {
 804                 for (i = 0; i < sensitive_data.nkeys; i++) {
 805                         if (sensitive_data.keys[i] != NULL) {
 806                                 /* Destroys contents safely */
 807                                 debug3("clear hostkey %d", i);
 808                                 key_free(sensitive_data.keys[i]);
 809                                 sensitive_data.keys[i] = NULL;
 810                         }
 811                 }
 812                 xfree(sensitive_data.keys);
 813         }
 814         for (i = 0; i < options.num_identity_files; i++) {
 815                 if (options.identity_files[i]) {
 816                         xfree(options.identity_files[i]);
 817                         options.identity_files[i] = NULL;
 818                 }
 819                 if (options.identity_keys[i]) {
 820                         key_free(options.identity_keys[i]);
 821                         options.identity_keys[i] = NULL;
 822                 }
 823         }
 824
 825         exit_status = compat20 ? ssh_session2() : ssh_session();
 826         packet_close();
 827
 828         if (options.control_path != NULL && control_fd != -1)
 829                 unlink(options.control_path);
 830
 831         /*
 832          * Send SIGHUP to proxy command if used. We don't wait() in
 833          * case it hangs and instead rely on init to reap the child
 834          */
 835         if (proxy_command_pid > 1)
 836                 kill(proxy_command_pid, SIGHUP);
 837
 838         return exit_status;
 839 }
 840
 841 static void
 842 ssh_init_forwarding(void)
 843 {
 844         int success = 0;
 845         int i;
 846
 847         /* Initiate local TCP/IP port forwardings. */
 848         for (i = 0; i < options.num_local_forwards; i++) {
 849                 debug("Local connections to %.200s:%d forwarded to remote "
 850                     "address %.200s:%d",
 851                     (options.local_forwards[i].listen_host == NULL) ?
 852                     (options.gateway_ports ? "*" : "LOCALHOST") :
 853                     options.local_forwards[i].listen_host,
 854                     options.local_forwards[i].listen_port,
 855                     options.local_forwards[i].connect_host,
 856                     options.local_forwards[i].connect_port);
 857                 success += channel_setup_local_fwd_listener(
 858                     options.local_forwards[i].listen_host,
 859                     options.local_forwards[i].listen_port,
 860                     options.local_forwards[i].connect_host,
 861                     options.local_forwards[i].connect_port,
 862                     options.gateway_ports);
 863         }
 864         if (i > 0 && success != i && options.exit_on_forward_failure)
 865                 fatal("Could not request local forwarding.");
 866         if (i > 0 && success == 0)
 867                 error("Could not request local forwarding.");
 868
 869         /* Initiate remote TCP/IP port forwardings. */
 870         for (i = 0; i < options.num_remote_forwards; i++) {
 871                 debug("Remote connections from %.200s:%d forwarded to "
 872                     "local address %.200s:%d",
 873                     (options.remote_forwards[i].listen_host == NULL) ?
 874                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 875                     options.remote_forwards[i].listen_port,
 876                     options.remote_forwards[i].connect_host,
 877                     options.remote_forwards[i].connect_port);
 878                 if (channel_request_remote_forwarding(
 879                     options.remote_forwards[i].listen_host,
 880                     options.remote_forwards[i].listen_port,
 881                     options.remote_forwards[i].connect_host,
 882                     options.remote_forwards[i].connect_port) < 0) {
 883                         if (options.exit_on_forward_failure)
 884                                 fatal("Could not request remote forwarding.");
 885                         else
 886                                 logit("Warning: Could not request remote "
 887                                     "forwarding.");
 888                 }
 889         }
 890
 891         /* Initiate tunnel forwarding. */
 892         if (options.tun_open != SSH_TUNMODE_NO) {
 893                 if (client_request_tun_fwd(options.tun_open,
 894                     options.tun_local, options.tun_remote) == -1) {
 895                         if (options.exit_on_forward_failure)
 896                                 fatal("Could not request tunnel forwarding.");
 897                         else
 898                                 error("Could not request tunnel forwarding.");
 899                 }
 900         }
 901 }
 902
 903 static void
 904 check_agent_present(void)
 905 {
 906         if (options.forward_agent) {
 907                 /* Clear agent forwarding if we don't have an agent. */
 908                 if (!ssh_agent_present())
 909                         options.forward_agent = 0;
 910         }
 911 }
 912
 913 static int
 914 ssh_session(void)
 915 {
 916         int type;
 917         int interactive = 0;
 918         int have_tty = 0;
 919         struct winsize ws;
 920         char *cp;
 921         const char *display;
 922
 923         /* Enable compression if requested. */
 924         if (options.compression) {
 925                 debug("Requesting compression at level %d.", options.compression_level);
 926
 927                 if (options.compression_level < 1 || options.compression_level > 9)
 928                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 929
 930                 /* Send the request. */
 931                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 932                 packet_put_int(options.compression_level);
 933                 packet_send();
 934                 packet_write_wait();
 935                 type = packet_read();
 936                 if (type == SSH_SMSG_SUCCESS)
 937                         packet_start_compression(options.compression_level);
 938                 else if (type == SSH_SMSG_FAILURE)
 939                         logit("Warning: Remote host refused compression.");
 940                 else
 941                         packet_disconnect("Protocol error waiting for compression response.");
 942         }
 943         /* Allocate a pseudo tty if appropriate. */
 944         if (tty_flag) {
 945                 debug("Requesting pty.");
 946
 947                 /* Start the packet. */
 948                 packet_start(SSH_CMSG_REQUEST_PTY);
 949
 950                 /* Store TERM in the packet.  There is no limit on the
 951                    length of the string. */
 952                 cp = getenv("TERM");
 953                 if (!cp)
 954                         cp = "";
 955                 packet_put_cstring(cp);
 956
 957                 /* Store window size in the packet. */
 958                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 959                         memset(&ws, 0, sizeof(ws));
 960                 packet_put_int((u_int)ws.ws_row);
 961                 packet_put_int((u_int)ws.ws_col);
 962                 packet_put_int((u_int)ws.ws_xpixel);
 963                 packet_put_int((u_int)ws.ws_ypixel);
 964
 965                 /* Store tty modes in the packet. */
 966                 tty_make_modes(fileno(stdin), NULL);
 967
 968                 /* Send the packet, and wait for it to leave. */
 969                 packet_send();
 970                 packet_write_wait();
 971
 972                 /* Read response from the server. */
 973                 type = packet_read();
 974                 if (type == SSH_SMSG_SUCCESS) {
 975                         interactive = 1;
 976                         have_tty = 1;
 977                 } else if (type == SSH_SMSG_FAILURE)
 978                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 979                 else
 980                         packet_disconnect("Protocol error waiting for pty request response.");
 981         }
 982         /* Request X11 forwarding if enabled and DISPLAY is set. */
 983         display = getenv("DISPLAY");
 984         if (options.forward_x11 && display != NULL) {
 985                 char *proto, *data;
 986                 /* Get reasonable local authentication information. */
 987                 client_x11_get_proto(display, options.xauth_location,
 988                     options.forward_x11_trusted, &proto, &data);
 989                 /* Request forwarding with authentication spoofing. */
 990                 debug("Requesting X11 forwarding with authentication spoofing.");
 991                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 992
 993                 /* Read response from the server. */
 994                 type = packet_read();
 995                 if (type == SSH_SMSG_SUCCESS) {
 996                         interactive = 1;
 997                 } else if (type == SSH_SMSG_FAILURE) {
 998                         logit("Warning: Remote host denied X11 forwarding.");
 999                 } else {
1000                         packet_disconnect("Protocol error waiting for X11 forwarding");
1001                 }
1002         }
1003         /* Tell the packet module whether this is an interactive session. */
1004         packet_set_interactive(interactive);
1005
1006         /* Request authentication agent forwarding if appropriate. */
1007         check_agent_present();
1008
1009         if (options.forward_agent) {
1010                 debug("Requesting authentication agent forwarding.");
1011                 auth_request_forwarding();
1012
1013                 /* Read response from the server. */
1014                 type = packet_read();
1015                 packet_check_eom();
1016                 if (type != SSH_SMSG_SUCCESS)
1017                         logit("Warning: Remote host denied authentication agent forwarding.");
1018         }
1019
1020         /* Initiate port forwardings. */
1021         ssh_init_forwarding();
1022
1023         /* Execute a local command */
1024         if (options.local_command != NULL &&
1025             options.permit_local_command)
1026                 ssh_local_cmd(options.local_command);
1027
1028         /* If requested, let ssh continue in the background. */
1029         if (fork_after_authentication_flag)
1030                 if (daemon(1, 1) < 0)
1031                         fatal("daemon() failed: %.200s", strerror(errno));
1032
1033         /*
1034          * If a command was specified on the command line, execute the
1035          * command now. Otherwise request the server to start a shell.
1036          */
1037         if (buffer_len(&command) > 0) {
1038                 int len = buffer_len(&command);
1039                 if (len > 900)
1040                         len = 900;
1041                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1042                 packet_start(SSH_CMSG_EXEC_CMD);
1043                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1044                 packet_send();
1045                 packet_write_wait();
1046         } else {
1047                 debug("Requesting shell.");
1048                 packet_start(SSH_CMSG_EXEC_SHELL);
1049                 packet_send();
1050                 packet_write_wait();
1051         }
1052
1053         /* Enter the interactive session. */
1054         return client_loop(have_tty, tty_flag ?
1055             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1056 }
1057
1058 static void
1059 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1060 {
1061         int id, len;
1062
1063         id = packet_get_int();
1064         len = buffer_len(&command);
1065         if (len > 900)
1066                 len = 900;
1067         packet_check_eom();
1068         if (type == SSH2_MSG_CHANNEL_FAILURE)
1069                 fatal("Request for subsystem '%.*s' failed on channel %d",
1070                     len, (u_char *)buffer_ptr(&command), id);
1071 }
1072
1073 void
1074 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1075 {
1076         int i;
1077
1078         i = client_global_request_id++;
1079         if (i >= options.num_remote_forwards)
1080                 return;
1081         debug("remote forward %s for: listen %d, connect %s:%d",
1082             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1083             options.remote_forwards[i].listen_port,
1084             options.remote_forwards[i].connect_host,
1085             options.remote_forwards[i].connect_port);
1086         if (type == SSH2_MSG_REQUEST_FAILURE) {
1087                 if (options.exit_on_forward_failure)
1088                         fatal("Error: remote port forwarding failed for "
1089                             "listen port %d",
1090                             options.remote_forwards[i].listen_port);
1091                 else
1092                         logit("Warning: remote port forwarding failed for "
1093                             "listen port %d",
1094                             options.remote_forwards[i].listen_port);
1095         }
1096 }
1097
1098 static void
1099 ssh_control_listener(void)
1100 {
1101         struct sockaddr_un addr;
1102         mode_t old_umask;
1103         int addr_len;
1104
1105         if (options.control_path == NULL ||
1106             options.control_master == SSHCTL_MASTER_NO)
1107                 return;
1108
1109         debug("setting up multiplex master socket");
1110
1111         memset(&addr, '\0', sizeof(addr));
1112         addr.sun_family = AF_UNIX;
1113         addr_len = offsetof(struct sockaddr_un, sun_path) +
1114             strlen(options.control_path) + 1;
1115
1116         if (strlcpy(addr.sun_path, options.control_path,
1117             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1118                 fatal("ControlPath too long");
1119
1120         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1121                 fatal("%s socket(): %s", __func__, strerror(errno));
1122
1123         old_umask = umask(0177);
1124         if (bind(control_fd, (struct sockaddr *)&addr, addr_len) == -1) {
1125                 control_fd = -1;
1126                 if (errno == EINVAL || errno == EADDRINUSE)
1127                         fatal("ControlSocket %s already exists",
1128                             options.control_path);
1129                 else
1130                         fatal("%s bind(): %s", __func__, strerror(errno));
1131         }
1132         umask(old_umask);
1133
1134         if (listen(control_fd, 64) == -1)
1135                 fatal("%s listen(): %s", __func__, strerror(errno));
1136
1137         set_nonblock(control_fd);
1138 }
1139
1140 /* request pty/x11/agent/tcpfwd/shell for channel */
1141 static void
1142 ssh_session2_setup(int id, void *arg)
1143 {
1144         extern char **environ;
1145         const char *display;
1146         int interactive = tty_flag;
1147
1148         display = getenv("DISPLAY");
1149         if (options.forward_x11 && display != NULL) {
1150                 char *proto, *data;
1151                 /* Get reasonable local authentication information. */
1152                 client_x11_get_proto(display, options.xauth_location,
1153                     options.forward_x11_trusted, &proto, &data);
1154                 /* Request forwarding with authentication spoofing. */
1155                 debug("Requesting X11 forwarding with authentication spoofing.");
1156                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1157                 interactive = 1;
1158                 /* XXX wait for reply */
1159         }
1160
1161         check_agent_present();
1162         if (options.forward_agent) {
1163                 debug("Requesting authentication agent forwarding.");
1164                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1165                 packet_send();
1166         }
1167
1168         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1169             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1170
1171         packet_set_interactive(interactive);
1172 }
1173
1174 /* open new channel for a session */
1175 static int
1176 ssh_session2_open(void)
1177 {
1178         Channel *c;
1179         int window, packetmax, in, out, err;
1180
1181         if (stdin_null_flag) {
1182                 in = open(_PATH_DEVNULL, O_RDONLY);
1183         } else {
1184                 in = dup(STDIN_FILENO);
1185         }
1186         out = dup(STDOUT_FILENO);
1187         err = dup(STDERR_FILENO);
1188
1189         if (in < 0 || out < 0 || err < 0)
1190                 fatal("dup() in/out/err failed");
1191
1192         /* enable nonblocking unless tty */
1193         if (!isatty(in))
1194                 set_nonblock(in);
1195         if (!isatty(out))
1196                 set_nonblock(out);
1197         if (!isatty(err))
1198                 set_nonblock(err);
1199
1200         window = CHAN_SES_WINDOW_DEFAULT;
1201         packetmax = CHAN_SES_PACKET_DEFAULT;
1202         if (tty_flag) {
1203                 window >>= 1;
1204                 packetmax >>= 1;
1205         }
1206         c = channel_new(
1207             "session", SSH_CHANNEL_OPENING, in, out, err,
1208             window, packetmax, CHAN_EXTENDED_WRITE,
1209             "client-session", /*nonblock*/0);
1210
1211         debug3("ssh_session2_open: channel_new: %d", c->self);
1212
1213         channel_send_open(c->self);
1214         if (!no_shell_flag)
1215                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1216
1217         return c->self;
1218 }
1219
1220 static int
1221 ssh_session2(void)
1222 {
1223         int id = -1;
1224
1225         /* XXX should be pre-session */
1226         ssh_init_forwarding();
1227
1228         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1229                 id = ssh_session2_open();
1230
1231         /* Execute a local command */
1232         if (options.local_command != NULL &&
1233             options.permit_local_command)
1234                 ssh_local_cmd(options.local_command);
1235
1236         /* Start listening for multiplex clients */
1237         ssh_control_listener();
1238
1239         /* If requested, let ssh continue in the background. */
1240         if (fork_after_authentication_flag)
1241                 if (daemon(1, 1) < 0)
1242                         fatal("daemon() failed: %.200s", strerror(errno));
1243
1244         return client_loop(tty_flag, tty_flag ?
1245             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1246 }
1247
1248 static void
1249 load_public_identity_files(void)
1250 {
1251         char *filename, *cp, thishost[NI_MAXHOST];
1252         char *pwdir = NULL, *pwname = NULL;
1253         int i = 0;
1254         Key *public;
1255         struct passwd *pw;
1256 #ifdef SMARTCARD
1257         Key **keys;
1258
1259         if (options.smartcard_device != NULL &&
1260             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1261             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL) {
1262                 int count = 0;
1263                 for (i = 0; keys[i] != NULL; i++) {
1264                         count++;
1265                         memmove(&options.identity_files[1], &options.identity_files[0],
1266                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1267                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1268                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1269                         options.num_identity_files++;
1270                         options.identity_keys[0] = keys[i];
1271                         options.identity_files[0] = sc_get_key_label(keys[i]);
1272                 }
1273                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1274                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1275                 i = count;
1276                 xfree(keys);
1277         }
1278 #endif /* SMARTCARD */
1279         if ((pw = getpwuid(original_real_uid)) == NULL)
1280                 fatal("load_public_identity_files: getpwuid failed");
1281         pwname = xstrdup(pw->pw_name);
1282         pwdir = xstrdup(pw->pw_dir);
1283         if (gethostname(thishost, sizeof(thishost)) == -1)
1284                 fatal("load_public_identity_files: gethostname: %s",
1285                     strerror(errno));
1286         for (; i < options.num_identity_files; i++) {
1287                 cp = tilde_expand_filename(options.identity_files[i],
1288                     original_real_uid);
1289                 filename = percent_expand(cp, "d", pwdir,
1290                     "u", pwname, "l", thishost, "h", host,
1291                     "r", options.user, (char *)NULL);
1292                 xfree(cp);
1293                 public = key_load_public(filename, NULL);
1294                 debug("identity file %s type %d", filename,
1295                     public ? public->type : -1);
1296                 xfree(options.identity_files[i]);
1297                 options.identity_files[i] = filename;
1298                 options.identity_keys[i] = public;
1299         }
1300         bzero(pwname, strlen(pwname));
1301         xfree(pwname);
1302         bzero(pwdir, strlen(pwdir));
1303         xfree(pwdir);
1304 }
1305
1306 static void
1307 control_client_sighandler(int signo)
1308 {
1309         control_client_terminate = signo;
1310 }
1311
1312 static void
1313 control_client_sigrelay(int signo)
1314 {
1315         int save_errno = errno;
1316
1317         if (control_server_pid > 1)
1318                 kill(control_server_pid, signo);
1319
1320         errno = save_errno;
1321 }
1322
1323 static int
1324 env_permitted(char *env)
1325 {
1326         int i, ret;
1327         char name[1024], *cp;
1328
1329         if ((cp = strchr(env, '=')) == NULL || cp == env)
1330                 return (0);
1331         ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
1332         if (ret <= 0 || (size_t)ret >= sizeof(name))
1333                 fatal("env_permitted: name '%.100s...' too long", env);
1334
1335         for (i = 0; i < options.num_send_env; i++)
1336                 if (match_pattern(name, options.send_env[i]))
1337                         return (1);
1338
1339         return (0);
1340 }
1341
1342 static void
1343 control_client(const char *path)
1344 {
1345         struct sockaddr_un addr;
1346         int i, r, fd, sock, exitval[2], num_env, addr_len;
1347         Buffer m;
1348         char *term;
1349         extern char **environ;
1350         u_int  flags;
1351
1352         if (mux_command == 0)
1353                 mux_command = SSHMUX_COMMAND_OPEN;
1354
1355         switch (options.control_master) {
1356         case SSHCTL_MASTER_AUTO:
1357         case SSHCTL_MASTER_AUTO_ASK:
1358                 debug("auto-mux: Trying existing master");
1359                 /* FALLTHROUGH */
1360         case SSHCTL_MASTER_NO:
1361                 break;
1362         default:
1363                 return;
1364         }
1365
1366         memset(&addr, '\0', sizeof(addr));
1367         addr.sun_family = AF_UNIX;
1368         addr_len = offsetof(struct sockaddr_un, sun_path) +
1369             strlen(path) + 1;
1370
1371         if (strlcpy(addr.sun_path, path,
1372             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1373                 fatal("ControlPath too long");
1374
1375         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1376                 fatal("%s socket(): %s", __func__, strerror(errno));
1377
1378         if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) {
1379                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1380                         fatal("Control socket connect(%.100s): %s", path,
1381                             strerror(errno));
1382                 }
1383                 if (errno == ENOENT)
1384                         debug("Control socket \"%.100s\" does not exist", path);
1385                 else {
1386                         error("Control socket connect(%.100s): %s", path,
1387                             strerror(errno));
1388                 }
1389                 close(sock);
1390                 return;
1391         }
1392
1393         if (stdin_null_flag) {
1394                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1395                         fatal("open(/dev/null): %s", strerror(errno));
1396                 if (dup2(fd, STDIN_FILENO) == -1)
1397                         fatal("dup2: %s", strerror(errno));
1398                 if (fd > STDERR_FILENO)
1399                         close(fd);
1400         }
1401
1402         term = getenv("TERM");
1403
1404         flags = 0;
1405         if (tty_flag)
1406                 flags |= SSHMUX_FLAG_TTY;
1407         if (subsystem_flag)
1408                 flags |= SSHMUX_FLAG_SUBSYS;
1409         if (options.forward_x11)
1410                 flags |= SSHMUX_FLAG_X11_FWD;
1411         if (options.forward_agent)
1412                 flags |= SSHMUX_FLAG_AGENT_FWD;
1413
1414         signal(SIGPIPE, SIG_IGN);
1415
1416         buffer_init(&m);
1417
1418         /* Send our command to server */
1419         buffer_put_int(&m, mux_command);
1420         buffer_put_int(&m, flags);
1421         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1422                 fatal("%s: msg_send", __func__);
1423         buffer_clear(&m);
1424
1425         /* Get authorisation status and PID of controlee */
1426         if (ssh_msg_recv(sock, &m) == -1)
1427                 fatal("%s: msg_recv", __func__);
1428         if (buffer_get_char(&m) != SSHMUX_VER)
1429                 fatal("%s: wrong version", __func__);
1430         if (buffer_get_int(&m) != 1)
1431                 fatal("Connection to master denied");
1432         control_server_pid = buffer_get_int(&m);
1433
1434         buffer_clear(&m);
1435
1436         switch (mux_command) {
1437         case SSHMUX_COMMAND_ALIVE_CHECK:
1438                 fprintf(stderr, "Master running (pid=%d)\r\n",
1439                     control_server_pid);
1440                 exit(0);
1441         case SSHMUX_COMMAND_TERMINATE:
1442                 fprintf(stderr, "Exit request sent.\r\n");
1443                 exit(0);
1444         case SSHMUX_COMMAND_OPEN:
1445                 /* continue below */
1446                 break;
1447         default:
1448                 fatal("silly mux_command %d", mux_command);
1449         }
1450
1451         /* SSHMUX_COMMAND_OPEN */
1452         buffer_put_cstring(&m, term ? term : "");
1453         buffer_append(&command, "\0", 1);
1454         buffer_put_cstring(&m, buffer_ptr(&command));
1455
1456         if (options.num_send_env == 0 || environ == NULL) {
1457                 buffer_put_int(&m, 0);
1458         } else {
1459                 /* Pass environment */
1460                 num_env = 0;
1461                 for (i = 0; environ[i] != NULL; i++)
1462                         if (env_permitted(environ[i]))
1463                                 num_env++; /* Count */
1464
1465                 buffer_put_int(&m, num_env);
1466
1467                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1468                         if (env_permitted(environ[i])) {
1469                                 num_env--;
1470                                 buffer_put_cstring(&m, environ[i]);
1471                         }
1472         }
1473
1474         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1475                 fatal("%s: msg_send", __func__);
1476
1477         if (mm_send_fd(sock, STDIN_FILENO) == -1 ||
1478             mm_send_fd(sock, STDOUT_FILENO) == -1 ||
1479             mm_send_fd(sock, STDERR_FILENO) == -1)
1480                 fatal("%s: send fds failed", __func__);
1481
1482         /* Wait for reply, so master has a chance to gather ttymodes */
1483         buffer_clear(&m);
1484         if (ssh_msg_recv(sock, &m) == -1)
1485                 fatal("%s: msg_recv", __func__);
1486         if (buffer_get_char(&m) != SSHMUX_VER)
1487                 fatal("%s: wrong version", __func__);
1488         buffer_free(&m);
1489
1490         signal(SIGHUP, control_client_sighandler);
1491         signal(SIGINT, control_client_sighandler);
1492         signal(SIGTERM, control_client_sighandler);
1493         signal(SIGWINCH, control_client_sigrelay);
1494
1495         if (tty_flag)
1496                 enter_raw_mode();
1497
1498         /*
1499          * Stick around until the controlee closes the client_fd.
1500          * Before it does, it is expected to write this process' exit
1501          * value (one int). This process must read the value and wait for
1502          * the closure of the client_fd; if this one closes early, the
1503          * multiplex master will terminate early too (possibly losing data).
1504          */
1505         exitval[0] = 0;
1506         for (i = 0; !control_client_terminate && i < (int)sizeof(exitval);) {
1507                 r = read(sock, (char *)exitval + i, sizeof(exitval) - i);
1508                 if (r == 0) {
1509                         debug2("Received EOF from master");
1510                         break;
1511                 }
1512                 if (r == -1) {
1513                         if (errno == EINTR)
1514                                 continue;
1515                         fatal("%s: read %s", __func__, strerror(errno));
1516                 }
1517                 i += r;
1518         }
1519
1520         close(sock);
1521         leave_raw_mode();
1522         if (i > (int)sizeof(int))
1523                 fatal("%s: master returned too much data (%d > %lu)",
1524                     __func__, i, sizeof(int));
1525         if (control_client_terminate) {
1526                 debug2("Exiting on signal %d", control_client_terminate);
1527                 exitval[0] = 255;
1528         } else if (i < (int)sizeof(int)) {
1529                 debug2("Control master terminated unexpectedly");
1530                 exitval[0] = 255;
1531         } else
1532                 debug2("Received exit status from master %d", exitval[0]);
1533
1534         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1535                 fprintf(stderr, "Shared connection to %s closed.\r\n", host);
1536
1537         exit(exitval[0]);
1538 }