openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.301 2007/08/07 07:32:53 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
  76 #include "xmalloc.h"
  77 #include "ssh.h"
  78 #include "ssh1.h"
  79 #include "ssh2.h"
  80 #include "compat.h"
  81 #include "cipher.h"
  82 #include "packet.h"
  83 #include "buffer.h"
  84 #include "channels.h"
  85 #include "key.h"
  86 #include "authfd.h"
  87 #include "authfile.h"
  88 #include "pathnames.h"
  89 #include "dispatch.h"
  90 #include "clientloop.h"
  91 #include "log.h"
  92 #include "readconf.h"
  93 #include "sshconnect.h"
  94 #include "misc.h"
  95 #include "kex.h"
  96 #include "mac.h"
  97 #include "sshpty.h"
  98 #include "match.h"
  99 #include "msg.h"
 100 #include "monitor_fdpass.h"
 101 #include "uidswap.h"
 102 #include "version.h"
 103
 104 #ifdef SMARTCARD
 105 #include "scard.h"
 106 #endif
 107
 108 extern char *__progname;
 109
 110 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
 111 int debug_flag = 0;
 112
 113 /* Flag indicating whether a tty should be allocated */
 114 int tty_flag = 0;
 115 int no_tty_flag = 0;
 116 int force_tty_flag = 0;
 117
 118 /* don't exec a shell */
 119 int no_shell_flag = 0;
 120
 121 /*
 122  * Flag indicating that nothing should be read from stdin.  This can be set
 123  * on the command line.
 124  */
 125 int stdin_null_flag = 0;
 126
 127 /*
 128  * Flag indicating that ssh should fork after authentication.  This is useful
 129  * so that the passphrase can be entered manually, and then ssh goes to the
 130  * background.
 131  */
 132 int fork_after_authentication_flag = 0;
 133
 134 /*
 135  * General data structure for command line options and options configurable
 136  * in configuration files.  See readconf.h.
 137  */
 138 Options options;
 139
 140 /* optional user configfile */
 141 char *config = NULL;
 142
 143 /*
 144  * Name of the host we are connecting to.  This is the name given on the
 145  * command line, or the HostName specified for the user-supplied name in a
 146  * configuration file.
 147  */
 148 char *host;
 149
 150 /* socket address the host resolves to */
 151 struct sockaddr_storage hostaddr;
 152
 153 /* Private host keys. */
 154 Sensitive sensitive_data;
 155
 156 /* Original real UID. */
 157 uid_t original_real_uid;
 158 uid_t original_effective_uid;
 159
 160 /* command to be executed */
 161 Buffer command;
 162
 163 /* Should we execute a command or invoke a subsystem? */
 164 int subsystem_flag = 0;
 165
 166 /* # of replies received for global requests */
 167 static int client_global_request_id = 0;
 168
 169 /* pid of proxycommand child process */
 170 pid_t proxy_command_pid = 0;
 171
 172 /* fd to control socket */
 173 int control_fd = -1;
 174
 175 /* Multiplexing control command */
 176 static u_int mux_command = 0;
 177
 178 /* Only used in control client mode */
 179 volatile sig_atomic_t control_client_terminate = 0;
 180 u_int control_server_pid = 0;
 181
 182 /* Prints a help message to the user.  This function never returns. */
 183
 184 static void
 185 usage(void)
 186 {
 187         fprintf(stderr,
 188 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 189 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 190 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 191 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 192 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 193 "           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
 194         );
 195         exit(255);
 196 }
 197
 198 static int ssh_session(void);
 199 static int ssh_session2(void);
 200 static void load_public_identity_files(void);
 201 static void control_client(const char *path);
 202
 203 /*
 204  * Main program for the ssh client.
 205  */
 206 int
 207 main(int ac, char **av)
 208 {
 209         int i, opt, exit_status;
 210         char *p, *cp, *line, buf[256];
 211         struct stat st;
 212         struct passwd *pw;
 213         int dummy;
 214         extern int optind, optreset;
 215         extern char *optarg;
 216         struct servent *sp;
 217         Forward fwd;
 218
 219         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 220         sanitise_stdfd();
 221
 222         __progname = ssh_get_progname(av[0]);
 223         init_rng();
 224
 225         /*
 226          * Save the original real uid.  It will be needed later (uid-swapping
 227          * may clobber the real uid).
 228          */
 229         original_real_uid = getuid();
 230         original_effective_uid = geteuid();
 231
 232         /*
 233          * Use uid-swapping to give up root privileges for the duration of
 234          * option processing.  We will re-instantiate the rights when we are
 235          * ready to create the privileged port, and will permanently drop
 236          * them when the port has been created (actually, when the connection
 237          * has been made, as we may need to create the port several times).
 238          */
 239         PRIV_END;
 240
 241 #ifdef HAVE_SETRLIMIT
 242         /* If we are installed setuid root be careful to not drop core. */
 243         if (original_real_uid != original_effective_uid) {
 244                 struct rlimit rlim;
 245                 rlim.rlim_cur = rlim.rlim_max = 0;
 246                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 247                         fatal("setrlimit failed: %.100s", strerror(errno));
 248         }
 249 #endif
 250         /* Get user data. */
 251         pw = getpwuid(original_real_uid);
 252         if (!pw) {
 253                 logit("You don't exist, go away!");
 254                 exit(255);
 255         }
 256         /* Take a copy of the returned structure. */
 257         pw = pwcopy(pw);
 258
 259         /*
 260          * Set our umask to something reasonable, as some files are created
 261          * with the default umask.  This will make them world-readable but
 262          * writable only by the owner, which is ok for all files for which we
 263          * don't set the modes explicitly.
 264          */
 265         umask(022);
 266
 267         /* Initialize option structure to indicate that no values have been set. */
 268         initialize_options(&options);
 269
 270         /* Parse command-line arguments. */
 271         host = NULL;
 272
 273  again:
 274         while ((opt = getopt(ac, av,
 275             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:KL:MNO:PR:S:TVw:XY")) != -1) {
 276                 switch (opt) {
 277                 case '1':
 278                         options.protocol = SSH_PROTO_1;
 279                         break;
 280                 case '2':
 281                         options.protocol = SSH_PROTO_2;
 282                         break;
 283                 case '4':
 284                         options.address_family = AF_INET;
 285                         break;
 286                 case '6':
 287                         options.address_family = AF_INET6;
 288                         break;
 289                 case 'n':
 290                         stdin_null_flag = 1;
 291                         break;
 292                 case 'f':
 293                         fork_after_authentication_flag = 1;
 294                         stdin_null_flag = 1;
 295                         break;
 296                 case 'x':
 297                         options.forward_x11 = 0;
 298                         break;
 299                 case 'X':
 300                         options.forward_x11 = 1;
 301                         break;
 302                 case 'Y':
 303                         options.forward_x11 = 1;
 304                         options.forward_x11_trusted = 1;
 305                         break;
 306                 case 'g':
 307                         options.gateway_ports = 1;
 308                         break;
 309                 case 'O':
 310                         if (strcmp(optarg, "check") == 0)
 311                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 312                         else if (strcmp(optarg, "exit") == 0)
 313                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 314                         else
 315                                 fatal("Invalid multiplex command.");
 316                         break;
 317                 case 'P':       /* deprecated */
 318                         options.use_privileged_port = 0;
 319                         break;
 320                 case 'a':
 321                         options.forward_agent = 0;
 322                         break;
 323                 case 'A':
 324                         options.forward_agent = 1;
 325                         break;
 326                 case 'k':
 327                         options.gss_deleg_creds = 0;
 328                         break;
 329                 case 'K':
 330                         options.gss_authentication = 1;
 331                         options.gss_deleg_creds = 1;
 332                         break;
 333                 case 'i':
 334                         if (stat(optarg, &st) < 0) {
 335                                 fprintf(stderr, "Warning: Identity file %s "
 336                                     "not accessible: %s.\n", optarg,
 337                                     strerror(errno));
 338                                 break;
 339                         }
 340                         if (options.num_identity_files >=
 341                             SSH_MAX_IDENTITY_FILES)
 342                                 fatal("Too many identity files specified "
 343                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 344                         options.identity_files[options.num_identity_files++] =
 345                             xstrdup(optarg);
 346                         break;
 347                 case 'I':
 348 #ifdef SMARTCARD
 349                         options.smartcard_device = xstrdup(optarg);
 350 #else
 351                         fprintf(stderr, "no support for smartcards.\n");
 352 #endif
 353                         break;
 354                 case 't':
 355                         if (tty_flag)
 356                                 force_tty_flag = 1;
 357                         tty_flag = 1;
 358                         break;
 359                 case 'v':
 360                         if (debug_flag == 0) {
 361                                 debug_flag = 1;
 362                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 363                         } else {
 364                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 365                                         options.log_level++;
 366                                 break;
 367                         }
 368                         /* FALLTHROUGH */
 369                 case 'V':
 370                         fprintf(stderr, "%s, %s\n",
 371                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 372                         if (opt == 'V')
 373                                 exit(0);
 374                         break;
 375                 case 'w':
 376                         if (options.tun_open == -1)
 377                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 378                         options.tun_local = a2tun(optarg, &options.tun_remote);
 379                         if (options.tun_local == SSH_TUNID_ERR) {
 380                                 fprintf(stderr, "Bad tun device '%s'\n", optarg);
 381                                 exit(255);
 382                         }
 383                         break;
 384                 case 'q':
 385                         options.log_level = SYSLOG_LEVEL_QUIET;
 386                         break;
 387                 case 'e':
 388                         if (optarg[0] == '^' && optarg[2] == 0 &&
 389                             (u_char) optarg[1] >= 64 &&
 390                             (u_char) optarg[1] < 128)
 391                                 options.escape_char = (u_char) optarg[1] & 31;
 392                         else if (strlen(optarg) == 1)
 393                                 options.escape_char = (u_char) optarg[0];
 394                         else if (strcmp(optarg, "none") == 0)
 395                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 396                         else {
 397                                 fprintf(stderr, "Bad escape character '%s'.\n",
 398                                     optarg);
 399                                 exit(255);
 400                         }
 401                         break;
 402                 case 'c':
 403                         if (ciphers_valid(optarg)) {
 404                                 /* SSH2 only */
 405                                 options.ciphers = xstrdup(optarg);
 406                                 options.cipher = SSH_CIPHER_INVALID;
 407                         } else {
 408                                 /* SSH1 only */
 409                                 options.cipher = cipher_number(optarg);
 410                                 if (options.cipher == -1) {
 411                                         fprintf(stderr,
 412                                             "Unknown cipher type '%s'\n",
 413                                             optarg);
 414                                         exit(255);
 415                                 }
 416                                 if (options.cipher == SSH_CIPHER_3DES)
 417                                         options.ciphers = "3des-cbc";
 418                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 419                                         options.ciphers = "blowfish-cbc";
 420                                 else
 421                                         options.ciphers = (char *)-1;
 422                         }
 423                         break;
 424                 case 'm':
 425                         if (mac_valid(optarg))
 426                                 options.macs = xstrdup(optarg);
 427                         else {
 428                                 fprintf(stderr, "Unknown mac type '%s'\n",
 429                                     optarg);
 430                                 exit(255);
 431                         }
 432                         break;
 433                 case 'M':
 434                         if (options.control_master == SSHCTL_MASTER_YES)
 435                                 options.control_master = SSHCTL_MASTER_ASK;
 436                         else
 437                                 options.control_master = SSHCTL_MASTER_YES;
 438                         break;
 439                 case 'p':
 440                         options.port = a2port(optarg);
 441                         if (options.port == 0) {
 442                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 443                                 exit(255);
 444                         }
 445                         break;
 446                 case 'l':
 447                         options.user = optarg;
 448                         break;
 449
 450                 case 'L':
 451                         if (parse_forward(&fwd, optarg))
 452                                 add_local_forward(&options, &fwd);
 453                         else {
 454                                 fprintf(stderr,
 455                                     "Bad local forwarding specification '%s'\n",
 456                                     optarg);
 457                                 exit(255);
 458                         }
 459                         break;
 460
 461                 case 'R':
 462                         if (parse_forward(&fwd, optarg)) {
 463                                 add_remote_forward(&options, &fwd);
 464                         } else {
 465                                 fprintf(stderr,
 466                                     "Bad remote forwarding specification "
 467                                     "'%s'\n", optarg);
 468                                 exit(255);
 469                         }
 470                         break;
 471
 472                 case 'D':
 473                         cp = p = xstrdup(optarg);
 474                         memset(&fwd, '\0', sizeof(fwd));
 475                         fwd.connect_host = "socks";
 476                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 477                                 fprintf(stderr, "Bad dynamic forwarding "
 478                                     "specification '%.100s'\n", optarg);
 479                                 exit(255);
 480                         }
 481                         if (cp != NULL) {
 482                                 fwd.listen_port = a2port(cp);
 483                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 484                         } else {
 485                                 fwd.listen_port = a2port(fwd.listen_host);
 486                                 fwd.listen_host = NULL;
 487                         }
 488
 489                         if (fwd.listen_port == 0) {
 490                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 491                                     optarg);
 492                                 exit(255);
 493                         }
 494                         add_local_forward(&options, &fwd);
 495                         xfree(p);
 496                         break;
 497
 498                 case 'C':
 499                         options.compression = 1;
 500                         break;
 501                 case 'N':
 502                         no_shell_flag = 1;
 503                         no_tty_flag = 1;
 504                         break;
 505                 case 'o':
 506                         dummy = 1;
 507                         line = xstrdup(optarg);
 508                         if (process_config_line(&options, host ? host : "",
 509                             line, "command-line", 0, &dummy) != 0)
 510                                 exit(255);
 511                         xfree(line);
 512                         break;
 513                 case 'T':
 514                         no_tty_flag = 1;
 515                         /* ensure that the user doesn't try to backdoor a */
 516                         /* null cipher switch on an interactive session */
 517                         /* so explicitly disable it no matter what */
 518                         options.none_switch=0;
 519                         break;
 520                 case 's':
 521                         subsystem_flag = 1;
 522                         break;
 523                 case 'S':
 524                         if (options.control_path != NULL)
 525                                 free(options.control_path);
 526                         options.control_path = xstrdup(optarg);
 527                         break;
 528                 case 'b':
 529                         options.bind_address = optarg;
 530                         break;
 531                 case 'F':
 532                         config = optarg;
 533                         break;
 534                 default:
 535                         usage();
 536                 }
 537         }
 538
 539         ac -= optind;
 540         av += optind;
 541
 542         if (ac > 0 && !host && **av != '-') {
 543                 if (strrchr(*av, '@')) {
 544                         p = xstrdup(*av);
 545                         cp = strrchr(p, '@');
 546                         if (cp == NULL || cp == p)
 547                                 usage();
 548                         options.user = p;
 549                         *cp = '\0';
 550                         host = ++cp;
 551                 } else
 552                         host = *av;
 553                 if (ac > 1) {
 554                         optind = optreset = 1;
 555                         goto again;
 556                 }
 557                 ac--, av++;
 558         }
 559
 560         /* Check that we got a host name. */
 561         if (!host)
 562                 usage();
 563
 564         SSLeay_add_all_algorithms();
 565         ERR_load_crypto_strings();
 566
 567         /* Initialize the command to execute on remote host. */
 568         buffer_init(&command);
 569
 570         /*
 571          * Save the command to execute on the remote host in a buffer. There
 572          * is no limit on the length of the command, except by the maximum
 573          * packet size.  Also sets the tty flag if there is no command.
 574          */
 575         if (!ac) {
 576                 /* No command specified - execute shell on a tty. */
 577                 tty_flag = 1;
 578                 if (subsystem_flag) {
 579                         fprintf(stderr,
 580                             "You must specify a subsystem to invoke.\n");
 581                         usage();
 582                 }
 583         } else {
 584                 /* A command has been specified.  Store it into the buffer. */
 585                 for (i = 0; i < ac; i++) {
 586                         if (i)
 587                                 buffer_append(&command, " ", 1);
 588                         buffer_append(&command, av[i], strlen(av[i]));
 589                 }
 590         }
 591
 592         /* Cannot fork to background if no command. */
 593         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 594                 fatal("Cannot fork into background without a command to execute.");
 595
 596         /* Allocate a tty by default if no command specified. */
 597         if (buffer_len(&command) == 0)
 598                 tty_flag = 1;
 599
 600         /* Force no tty */
 601         if (no_tty_flag)
 602                 tty_flag = 0;
 603         /* Do not allocate a tty if stdin is not a tty. */
 604         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 605                 if (tty_flag)
 606                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 607                 tty_flag = 0;
 608         }
 609
 610         /*
 611          * Initialize "log" output.  Since we are the client all output
 612          * actually goes to stderr.
 613          */
 614         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 615             SYSLOG_FACILITY_USER, 1);
 616
 617         /*
 618          * Read per-user configuration file.  Ignore the system wide config
 619          * file if the user specifies a config file on the command line.
 620          */
 621         if (config != NULL) {
 622                 if (!read_config_file(config, host, &options, 0))
 623                         fatal("Can't open user config file %.100s: "
 624                             "%.100s", config, strerror(errno));
 625         } else {
 626             /*
 627              * Since the config file parsing code aborts if it sees
 628              * options it doesn't recognize, allow users to put
 629              * options specific to compile-time add-ons in alternate
 630              * config files so their primary config file will
 631              * interoperate SSH versions that don't support those
 632              * options.
 633              */
 634 #ifdef GSSAPI
 635                 snprintf(buf, sizeof buf, "%.100s/%.100s.gssapi", pw->pw_dir,
 636                     _PATH_SSH_USER_CONFFILE);
 637                 (void)read_config_file(buf, host, &options, 1);
 638 #ifdef GSI
 639                 snprintf(buf, sizeof buf, "%.100s/%.100s.gsi", pw->pw_dir,
 640                     _PATH_SSH_USER_CONFFILE);
 641                 (void)read_config_file(buf, host, &options, 1);
 642 #endif
 643 #if defined(KRB5)
 644                 snprintf(buf, sizeof buf, "%.100s/%.100s.krb", pw->pw_dir,
 645                     _PATH_SSH_USER_CONFFILE);
 646                 (void)read_config_file(buf, host, &options, 1);
 647 #endif
 648 #endif
 649                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 650                     _PATH_SSH_USER_CONFFILE);
 651                 (void)read_config_file(buf, host, &options, 1);
 652
 653                 /* Read systemwide configuration file after use config. */
 654                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 655                     &options, 0);
 656         }
 657
 658         /* Fill configuration defaults. */
 659         fill_default_options(&options);
 660
 661         channel_set_af(options.address_family);
 662
 663         /* reinit */
 664         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 665
 666         seed_rng();
 667
 668         if (options.user == NULL) {
 669                 options.user = xstrdup(pw->pw_name);
 670                 options.implicit = 1;
 671         }
 672         else options.implicit = 0;
 673
 674         if (options.hostname != NULL)
 675                 host = options.hostname;
 676
 677         /* force lowercase for hostkey matching */
 678         if (options.host_key_alias != NULL) {
 679                 for (p = options.host_key_alias; *p; p++)
 680                         if (isupper(*p))
 681                                 *p = (char)tolower(*p);
 682         }
 683
 684         /* Get default port if port has not been set. */
 685         if (options.port == 0) {
 686                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 687                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 688         }
 689
 690         if (options.proxy_command != NULL &&
 691             strcmp(options.proxy_command, "none") == 0)
 692                 options.proxy_command = NULL;
 693         if (options.control_path != NULL &&
 694             strcmp(options.control_path, "none") == 0)
 695                 options.control_path = NULL;
 696
 697         if (options.control_path != NULL) {
 698                 char thishost[NI_MAXHOST];
 699
 700                 if (gethostname(thishost, sizeof(thishost)) == -1)
 701                         fatal("gethostname: %s", strerror(errno));
 702                 snprintf(buf, sizeof(buf), "%d", options.port);
 703                 cp = tilde_expand_filename(options.control_path,
 704                     original_real_uid);
 705                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 706                     "r", options.user, "l", thishost, (char *)NULL);
 707                 xfree(cp);
 708         }
 709         if (mux_command != 0 && options.control_path == NULL)
 710                 fatal("No ControlPath specified for \"-O\" command");
 711         if (options.control_path != NULL)
 712                 control_client(options.control_path);
 713
 714         /* Open a connection to the remote host. */
 715         if (ssh_connect(host, &hostaddr, options.port,
 716             options.address_family, options.connection_attempts,
 717 #ifdef HAVE_CYGWIN
 718             options.use_privileged_port,
 719 #else
 720             original_effective_uid == 0 && options.use_privileged_port,
 721 #endif
 722             options.proxy_command) != 0)
 723                 exit(255);
 724
 725         /*
 726          * If we successfully made the connection, load the host private key
 727          * in case we will need it later for combined rsa-rhosts
 728          * authentication. This must be done before releasing extra
 729          * privileges, because the file is only readable by root.
 730          * If we cannot access the private keys, load the public keys
 731          * instead and try to execute the ssh-keysign helper instead.
 732          */
 733         sensitive_data.nkeys = 0;
 734         sensitive_data.keys = NULL;
 735         sensitive_data.external_keysign = 0;
 736         if (options.rhosts_rsa_authentication ||
 737             options.hostbased_authentication) {
 738                 sensitive_data.nkeys = 3;
 739                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 740                     sizeof(Key));
 741
 742                 PRIV_START;
 743                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 744                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 745                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 746                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 747                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 748                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 749                 PRIV_END;
 750
 751                 if (options.hostbased_authentication == 1 &&
 752                     sensitive_data.keys[0] == NULL &&
 753                     sensitive_data.keys[1] == NULL &&
 754                     sensitive_data.keys[2] == NULL) {
 755                         sensitive_data.keys[1] = key_load_public(
 756                             _PATH_HOST_DSA_KEY_FILE, NULL);
 757                         sensitive_data.keys[2] = key_load_public(
 758                             _PATH_HOST_RSA_KEY_FILE, NULL);
 759                         sensitive_data.external_keysign = 1;
 760                 }
 761         }
 762         /*
 763          * Get rid of any extra privileges that we may have.  We will no
 764          * longer need them.  Also, extra privileges could make it very hard
 765          * to read identity files and other non-world-readable files from the
 766          * user's home directory if it happens to be on a NFS volume where
 767          * root is mapped to nobody.
 768          */
 769         if (original_effective_uid == 0) {
 770                 PRIV_START;
 771                 permanently_set_uid(pw);
 772         }
 773
 774         /*
 775          * Now that we are back to our own permissions, create ~/.ssh
 776          * directory if it doesn't already exist.
 777          */
 778         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 779         if (stat(buf, &st) < 0)
 780                 if (mkdir(buf, 0700) < 0)
 781                         error("Could not create directory '%.200s'.", buf);
 782
 783         /* load options.identity_files */
 784         load_public_identity_files();
 785
 786         /* Expand ~ in known host file names. */
 787         /* XXX mem-leaks: */
 788         options.system_hostfile =
 789             tilde_expand_filename(options.system_hostfile, original_real_uid);
 790         options.user_hostfile =
 791             tilde_expand_filename(options.user_hostfile, original_real_uid);
 792         options.system_hostfile2 =
 793             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 794         options.user_hostfile2 =
 795             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 796
 797         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 798
 799         /* Log into the remote system.  This never returns if the login fails. */
 800         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 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, options.hpn_disabled,
 863                     options.hpn_buffer_size);
 864         }
 865         if (i > 0 && success != i && options.exit_on_forward_failure)
 866                 fatal("Could not request local forwarding.");
 867         if (i > 0 && success == 0)
 868                 error("Could not request local forwarding.");
 869
 870         /* Initiate remote TCP/IP port forwardings. */
 871         for (i = 0; i < options.num_remote_forwards; i++) {
 872                 debug("Remote connections from %.200s:%d forwarded to "
 873                     "local address %.200s:%d",
 874                     (options.remote_forwards[i].listen_host == NULL) ?
 875                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 876                     options.remote_forwards[i].listen_port,
 877                     options.remote_forwards[i].connect_host,
 878                     options.remote_forwards[i].connect_port);
 879                 if (channel_request_remote_forwarding(
 880                     options.remote_forwards[i].listen_host,
 881                     options.remote_forwards[i].listen_port,
 882                     options.remote_forwards[i].connect_host,
 883                     options.remote_forwards[i].connect_port) < 0) {
 884                         if (options.exit_on_forward_failure)
 885                                 fatal("Could not request remote forwarding.");
 886                         else
 887                                 logit("Warning: Could not request remote "
 888                                     "forwarding.");
 889                 }
 890         }
 891
 892         /* Initiate tunnel forwarding. */
 893         if (options.tun_open != SSH_TUNMODE_NO) {
 894                 if (client_request_tun_fwd(options.tun_open,
 895                     options.tun_local, options.tun_remote) == -1) {
 896                         if (options.exit_on_forward_failure)
 897                                 fatal("Could not request tunnel forwarding.");
 898                         else
 899                                 error("Could not request tunnel forwarding.");
 900                 }
 901         }
 902 }
 903
 904 static void
 905 check_agent_present(void)
 906 {
 907         if (options.forward_agent) {
 908                 /* Clear agent forwarding if we don't have an agent. */
 909                 if (!ssh_agent_present())
 910                         options.forward_agent = 0;
 911         }
 912 }
 913
 914 static int
 915 ssh_session(void)
 916 {
 917         int type;
 918         int interactive = 0;
 919         int have_tty = 0;
 920         struct winsize ws;
 921         char *cp;
 922         const char *display;
 923
 924         /* Enable compression if requested. */
 925         if (options.compression) {
 926                 debug("Requesting compression at level %d.", options.compression_level);
 927
 928                 if (options.compression_level < 1 || options.compression_level > 9)
 929                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 930
 931                 /* Send the request. */
 932                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 933                 packet_put_int(options.compression_level);
 934                 packet_send();
 935                 packet_write_wait();
 936                 type = packet_read();
 937                 if (type == SSH_SMSG_SUCCESS)
 938                         packet_start_compression(options.compression_level);
 939                 else if (type == SSH_SMSG_FAILURE)
 940                         logit("Warning: Remote host refused compression.");
 941                 else
 942                         packet_disconnect("Protocol error waiting for compression response.");
 943         }
 944         /* Allocate a pseudo tty if appropriate. */
 945         if (tty_flag) {
 946                 debug("Requesting pty.");
 947
 948                 /* Start the packet. */
 949                 packet_start(SSH_CMSG_REQUEST_PTY);
 950
 951                 /* Store TERM in the packet.  There is no limit on the
 952                    length of the string. */
 953                 cp = getenv("TERM");
 954                 if (!cp)
 955                         cp = "";
 956                 packet_put_cstring(cp);
 957
 958                 /* Store window size in the packet. */
 959                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 960                         memset(&ws, 0, sizeof(ws));
 961                 packet_put_int((u_int)ws.ws_row);
 962                 packet_put_int((u_int)ws.ws_col);
 963                 packet_put_int((u_int)ws.ws_xpixel);
 964                 packet_put_int((u_int)ws.ws_ypixel);
 965
 966                 /* Store tty modes in the packet. */
 967                 tty_make_modes(fileno(stdin), NULL);
 968
 969                 /* Send the packet, and wait for it to leave. */
 970                 packet_send();
 971                 packet_write_wait();
 972
 973                 /* Read response from the server. */
 974                 type = packet_read();
 975                 if (type == SSH_SMSG_SUCCESS) {
 976                         interactive = 1;
 977                         have_tty = 1;
 978                 } else if (type == SSH_SMSG_FAILURE)
 979                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 980                 else
 981                         packet_disconnect("Protocol error waiting for pty request response.");
 982         }
 983         /* Request X11 forwarding if enabled and DISPLAY is set. */
 984         display = getenv("DISPLAY");
 985         if (options.forward_x11 && display != NULL) {
 986                 char *proto, *data;
 987                 /* Get reasonable local authentication information. */
 988                 client_x11_get_proto(display, options.xauth_location,
 989                     options.forward_x11_trusted, &proto, &data);
 990                 /* Request forwarding with authentication spoofing. */
 991                 debug("Requesting X11 forwarding with authentication spoofing.");
 992                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 993
 994                 /* Read response from the server. */
 995                 type = packet_read();
 996                 if (type == SSH_SMSG_SUCCESS) {
 997                         interactive = 1;
 998                 } else if (type == SSH_SMSG_FAILURE) {
 999                         logit("Warning: Remote host denied X11 forwarding.");
1000                 } else {
1001                         packet_disconnect("Protocol error waiting for X11 forwarding");
1002                 }
1003         }
1004         /* Tell the packet module whether this is an interactive session. */
1005         packet_set_interactive(interactive);
1006
1007         /* Request authentication agent forwarding if appropriate. */
1008         check_agent_present();
1009
1010         if (options.forward_agent) {
1011                 debug("Requesting authentication agent forwarding.");
1012                 auth_request_forwarding();
1013
1014                 /* Read response from the server. */
1015                 type = packet_read();
1016                 packet_check_eom();
1017                 if (type != SSH_SMSG_SUCCESS)
1018                         logit("Warning: Remote host denied authentication agent forwarding.");
1019         }
1020
1021         /* Initiate port forwardings. */
1022         ssh_init_forwarding();
1023
1024         /* If requested, let ssh continue in the background. */
1025         if (fork_after_authentication_flag)
1026                 if (daemon(1, 1) < 0)
1027                         fatal("daemon() failed: %.200s", strerror(errno));
1028
1029         /*
1030          * If a command was specified on the command line, execute the
1031          * command now. Otherwise request the server to start a shell.
1032          */
1033         if (buffer_len(&command) > 0) {
1034                 int len = buffer_len(&command);
1035                 if (len > 900)
1036                         len = 900;
1037                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1038                 packet_start(SSH_CMSG_EXEC_CMD);
1039                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1040                 packet_send();
1041                 packet_write_wait();
1042         } else {
1043                 debug("Requesting shell.");
1044                 packet_start(SSH_CMSG_EXEC_SHELL);
1045                 packet_send();
1046                 packet_write_wait();
1047         }
1048
1049         /* Enter the interactive session. */
1050         return client_loop(have_tty, tty_flag ?
1051             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1052 }
1053
1054 static void
1055 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1056 {
1057         int id, len;
1058
1059         id = packet_get_int();
1060         len = buffer_len(&command);
1061         if (len > 900)
1062                 len = 900;
1063         packet_check_eom();
1064         if (type == SSH2_MSG_CHANNEL_FAILURE)
1065                 fatal("Request for subsystem '%.*s' failed on channel %d",
1066                     len, (u_char *)buffer_ptr(&command), id);
1067 }
1068
1069 void
1070 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1071 {
1072         int i;
1073
1074         i = client_global_request_id++;
1075         if (i >= options.num_remote_forwards)
1076                 return;
1077         debug("remote forward %s for: listen %d, connect %s:%d",
1078             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1079             options.remote_forwards[i].listen_port,
1080             options.remote_forwards[i].connect_host,
1081             options.remote_forwards[i].connect_port);
1082         if (type == SSH2_MSG_REQUEST_FAILURE) {
1083                 if (options.exit_on_forward_failure)
1084                         fatal("Error: remote port forwarding failed for "
1085                             "listen port %d",
1086                             options.remote_forwards[i].listen_port);
1087                 else
1088                         logit("Warning: remote port forwarding failed for "
1089                             "listen port %d",
1090                             options.remote_forwards[i].listen_port);
1091         }
1092 }
1093
1094 static void
1095 ssh_control_listener(void)
1096 {
1097         struct sockaddr_un addr;
1098         mode_t old_umask;
1099         int addr_len;
1100
1101         if (options.control_path == NULL ||
1102             options.control_master == SSHCTL_MASTER_NO)
1103                 return;
1104
1105         debug("setting up multiplex master socket");
1106
1107         memset(&addr, '\0', sizeof(addr));
1108         addr.sun_family = AF_UNIX;
1109         addr_len = offsetof(struct sockaddr_un, sun_path) +
1110             strlen(options.control_path) + 1;
1111
1112         if (strlcpy(addr.sun_path, options.control_path,
1113             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1114                 fatal("ControlPath too long");
1115
1116         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1117                 fatal("%s socket(): %s", __func__, strerror(errno));
1118
1119         old_umask = umask(0177);
1120         if (bind(control_fd, (struct sockaddr *)&addr, addr_len) == -1) {
1121                 control_fd = -1;
1122                 if (errno == EINVAL || errno == EADDRINUSE)
1123                         fatal("ControlSocket %s already exists",
1124                             options.control_path);
1125                 else
1126                         fatal("%s bind(): %s", __func__, strerror(errno));
1127         }
1128         umask(old_umask);
1129
1130         if (listen(control_fd, 64) == -1)
1131                 fatal("%s listen(): %s", __func__, strerror(errno));
1132
1133         set_nonblock(control_fd);
1134 }
1135
1136 /* request pty/x11/agent/tcpfwd/shell for channel */
1137 static void
1138 ssh_session2_setup(int id, void *arg)
1139 {
1140         extern char **environ;
1141         const char *display;
1142         int interactive = tty_flag;
1143
1144         display = getenv("DISPLAY");
1145         if (options.forward_x11 && display != NULL) {
1146                 char *proto, *data;
1147                 /* Get reasonable local authentication information. */
1148                 client_x11_get_proto(display, options.xauth_location,
1149                     options.forward_x11_trusted, &proto, &data);
1150                 /* Request forwarding with authentication spoofing. */
1151                 debug("Requesting X11 forwarding with authentication spoofing.");
1152                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1153                 interactive = 1;
1154                 /* XXX wait for reply */
1155         }
1156
1157         check_agent_present();
1158         if (options.forward_agent) {
1159                 debug("Requesting authentication agent forwarding.");
1160                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1161                 packet_send();
1162         }
1163
1164         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1165             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1166
1167         packet_set_interactive(interactive);
1168 }
1169
1170 /* open new channel for a session */
1171 static int
1172 ssh_session2_open(void)
1173 {
1174         Channel *c;
1175         int window, packetmax, in, out, err;
1176         int sock;
1177         int socksize;
1178         int socksizelen = sizeof(int);
1179
1180         if (stdin_null_flag) {
1181                 in = open(_PATH_DEVNULL, O_RDONLY);
1182         } else {
1183                 in = dup(STDIN_FILENO);
1184         }
1185         out = dup(STDOUT_FILENO);
1186         err = dup(STDERR_FILENO);
1187
1188         if (in < 0 || out < 0 || err < 0)
1189                 fatal("dup() in/out/err failed");
1190
1191         /* enable nonblocking unless tty */
1192         if (!isatty(in))
1193                 set_nonblock(in);
1194         if (!isatty(out))
1195                 set_nonblock(out);
1196         if (!isatty(err))
1197                 set_nonblock(err);
1198
1199         /* we need to check to see if what they want to do about buffer */
1200         /* sizes here. In a hpn to nonhpn connection we want to limit */
1201         /* the window size to something reasonable in case the far side */
1202         /* has the large window bug. In hpn to hpn connection we want to */
1203         /* use the max window size but allow the user to override it */
1204         /* lastly if they disabled hpn then use the ssh std window size */
1205
1206         /* so why don't we just do a getsockopt() here and set the */
1207         /* ssh window to that? In the case of a autotuning receive */
1208         /* window the window would get stuck at the initial buffer */
1209         /* size generally less than 96k. Therefore we need to set the */
1210         /* maximum ssh window size to the maximum hpn buffer size */
1211         /* unless the user has specifically set the tcprcvbufpoll */
1212         /* to no. In which case we *can* just set the window to the */
1213         /* minimum of the hpn buffer size and tcp receive buffer size */
1214
1215         if(options.hpn_disabled)
1216         {
1217                 options.hpn_buffer_size = CHAN_SES_WINDOW_DEFAULT;
1218         }
1219         else if (datafellows & SSH_BUG_LARGEWINDOW)
1220         {
1221                 debug("HPN to Non-HPN Connection");
1222                 if (options.hpn_buffer_size < 0)
1223                         options.hpn_buffer_size = 2*1024*1024;
1224         }
1225         else
1226         {
1227                 if (options.hpn_buffer_size < 0)
1228                         options.hpn_buffer_size = BUFFER_MAX_LEN_HPN;
1229
1230                 /*create a socket but don't connect it */
1231                 /* we use that the get the rcv socket size */
1232                 sock = socket(AF_INET, SOCK_STREAM, 0);
1233                 /* if they are using the tcp_rcv_buf option */
1234                 /* attempt to set the buffer size to that */
1235                 if (options.tcp_rcv_buf)
1236                         setsockopt(sock, SOL_SOCKET, SO_RCVBUF, (void *)&options.tcp_rcv_buf,
1237                                    sizeof(options.tcp_rcv_buf));
1238                 getsockopt(sock, SOL_SOCKET, SO_RCVBUF,
1239                            &socksize, &socksizelen);
1240                 close(sock);
1241                 debug("socksize %d", socksize);
1242                 if (options.tcp_rcv_buf_poll <= 0)
1243                 {
1244                         options.hpn_buffer_size = MIN(socksize,options.hpn_buffer_size);
1245                         debug ("MIN of TCP RWIN and HPNBufferSize: %d", options.hpn_buffer_size);
1246                 }
1247                 else
1248                 {
1249                         if (options.tcp_rcv_buf > 0)
1250                                 options.hpn_buffer_size = MIN(options.tcp_rcv_buf, options.hpn_buffer_size);
1251                                 debug ("MIN of TCPRcvBuf and HPNBufferSize: %d", options.hpn_buffer_size);
1252                 }
1253
1254         }
1255
1256         debug("Final hpn_buffer_size = %d", options.hpn_buffer_size);
1257
1258         window = options.hpn_buffer_size;
1259
1260         packetmax = CHAN_SES_PACKET_DEFAULT;
1261         if (tty_flag) {
1262                 window = 4*CHAN_SES_PACKET_DEFAULT;
1263                 window >>= 1;
1264                 packetmax >>= 1;
1265         }
1266         c = channel_new(
1267             "session", SSH_CHANNEL_OPENING, in, out, err,
1268             window, packetmax, CHAN_EXTENDED_WRITE,
1269             "client-session", /*nonblock*/0);
1270
1271         if ((options.tcp_rcv_buf_poll > 0) && (!options.hpn_disabled)) {
1272                 c->dynamic_window = 1;
1273                 debug ("Enabled Dynamic Window Scaling\n");
1274         }
1275         debug3("ssh_session2_open: channel_new: %d", c->self);
1276
1277         channel_send_open(c->self);
1278         if (!no_shell_flag)
1279                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1280
1281         return c->self;
1282 }
1283
1284 static int
1285 ssh_session2(void)
1286 {
1287         int id = -1;
1288
1289         /* XXX should be pre-session */
1290         ssh_init_forwarding();
1291
1292         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1293                 id = ssh_session2_open();
1294
1295         /* Execute a local command */
1296         if (options.local_command != NULL &&
1297             options.permit_local_command)
1298                 ssh_local_cmd(options.local_command);
1299
1300         /* Start listening for multiplex clients */
1301         ssh_control_listener();
1302
1303         /* If requested, let ssh continue in the background. */
1304         if (fork_after_authentication_flag)
1305                 if (daemon(1, 1) < 0)
1306                         fatal("daemon() failed: %.200s", strerror(errno));
1307
1308         return client_loop(tty_flag, tty_flag ?
1309             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1310 }
1311
1312 static void
1313 load_public_identity_files(void)
1314 {
1315         char *filename, *cp, thishost[NI_MAXHOST];
1316         int i = 0;
1317         Key *public;
1318         struct passwd *pw;
1319 #ifdef SMARTCARD
1320         Key **keys;
1321
1322         if (options.smartcard_device != NULL &&
1323             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1324             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL) {
1325                 int count = 0;
1326                 for (i = 0; keys[i] != NULL; i++) {
1327                         count++;
1328                         memmove(&options.identity_files[1], &options.identity_files[0],
1329                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1330                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1331                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1332                         options.num_identity_files++;
1333                         options.identity_keys[0] = keys[i];
1334                         options.identity_files[0] = sc_get_key_label(keys[i]);
1335                 }
1336                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1337                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1338                 i = count;
1339                 xfree(keys);
1340         }
1341 #endif /* SMARTCARD */
1342         if ((pw = getpwuid(original_real_uid)) == NULL)
1343                 fatal("load_public_identity_files: getpwuid failed");
1344         if (gethostname(thishost, sizeof(thishost)) == -1)
1345                 fatal("load_public_identity_files: gethostname: %s",
1346                     strerror(errno));
1347         for (; i < options.num_identity_files; i++) {
1348                 cp = tilde_expand_filename(options.identity_files[i],
1349                     original_real_uid);
1350                 filename = percent_expand(cp, "d", pw->pw_dir,
1351                     "u", pw->pw_name, "l", thishost, "h", host,
1352                     "r", options.user, (char *)NULL);
1353                 xfree(cp);
1354                 public = key_load_public(filename, NULL);
1355                 debug("identity file %s type %d", filename,
1356                     public ? public->type : -1);
1357                 xfree(options.identity_files[i]);
1358                 options.identity_files[i] = filename;
1359                 options.identity_keys[i] = public;
1360         }
1361 }
1362
1363 static void
1364 control_client_sighandler(int signo)
1365 {
1366         control_client_terminate = signo;
1367 }
1368
1369 static void
1370 control_client_sigrelay(int signo)
1371 {
1372         if (control_server_pid > 1)
1373                 kill(control_server_pid, signo);
1374 }
1375
1376 static int
1377 env_permitted(char *env)
1378 {
1379         int i, ret;
1380         char name[1024], *cp;
1381
1382         if ((cp = strchr(env, '=')) == NULL || cp == env)
1383                 return (0);
1384         ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
1385         if (ret <= 0 || (size_t)ret >= sizeof(name))
1386                 fatal("env_permitted: name '%.100s...' too long", env);
1387
1388         for (i = 0; i < options.num_send_env; i++)
1389                 if (match_pattern(name, options.send_env[i]))
1390                         return (1);
1391
1392         return (0);
1393 }
1394
1395 static void
1396 control_client(const char *path)
1397 {
1398         struct sockaddr_un addr;
1399         int i, r, fd, sock, exitval[2], num_env, addr_len;
1400         Buffer m;
1401         char *term;
1402         extern char **environ;
1403         u_int  flags;
1404
1405         if (mux_command == 0)
1406                 mux_command = SSHMUX_COMMAND_OPEN;
1407
1408         switch (options.control_master) {
1409         case SSHCTL_MASTER_AUTO:
1410         case SSHCTL_MASTER_AUTO_ASK:
1411                 debug("auto-mux: Trying existing master");
1412                 /* FALLTHROUGH */
1413         case SSHCTL_MASTER_NO:
1414                 break;
1415         default:
1416                 return;
1417         }
1418
1419         memset(&addr, '\0', sizeof(addr));
1420         addr.sun_family = AF_UNIX;
1421         addr_len = offsetof(struct sockaddr_un, sun_path) +
1422             strlen(path) + 1;
1423
1424         if (strlcpy(addr.sun_path, path,
1425             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1426                 fatal("ControlPath too long");
1427
1428         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1429                 fatal("%s socket(): %s", __func__, strerror(errno));
1430
1431         if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) {
1432                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1433                         fatal("Control socket connect(%.100s): %s", path,
1434                             strerror(errno));
1435                 }
1436                 if (errno == ENOENT)
1437                         debug("Control socket \"%.100s\" does not exist", path);
1438                 else {
1439                         error("Control socket connect(%.100s): %s", path,
1440                             strerror(errno));
1441                 }
1442                 close(sock);
1443                 return;
1444         }
1445
1446         if (stdin_null_flag) {
1447                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1448                         fatal("open(/dev/null): %s", strerror(errno));
1449                 if (dup2(fd, STDIN_FILENO) == -1)
1450                         fatal("dup2: %s", strerror(errno));
1451                 if (fd > STDERR_FILENO)
1452                         close(fd);
1453         }
1454
1455         term = getenv("TERM");
1456
1457         flags = 0;
1458         if (tty_flag)
1459                 flags |= SSHMUX_FLAG_TTY;
1460         if (subsystem_flag)
1461                 flags |= SSHMUX_FLAG_SUBSYS;
1462         if (options.forward_x11)
1463                 flags |= SSHMUX_FLAG_X11_FWD;
1464         if (options.forward_agent)
1465                 flags |= SSHMUX_FLAG_AGENT_FWD;
1466
1467         buffer_init(&m);
1468
1469         /* Send our command to server */
1470         buffer_put_int(&m, mux_command);
1471         buffer_put_int(&m, flags);
1472         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1473                 fatal("%s: msg_send", __func__);
1474         buffer_clear(&m);
1475
1476         /* Get authorisation status and PID of controlee */
1477         if (ssh_msg_recv(sock, &m) == -1)
1478                 fatal("%s: msg_recv", __func__);
1479         if (buffer_get_char(&m) != SSHMUX_VER)
1480                 fatal("%s: wrong version", __func__);
1481         if (buffer_get_int(&m) != 1)
1482                 fatal("Connection to master denied");
1483         control_server_pid = buffer_get_int(&m);
1484
1485         buffer_clear(&m);
1486
1487         switch (mux_command) {
1488         case SSHMUX_COMMAND_ALIVE_CHECK:
1489                 fprintf(stderr, "Master running (pid=%d)\r\n",
1490                     control_server_pid);
1491                 exit(0);
1492         case SSHMUX_COMMAND_TERMINATE:
1493                 fprintf(stderr, "Exit request sent.\r\n");
1494                 exit(0);
1495         case SSHMUX_COMMAND_OPEN:
1496                 /* continue below */
1497                 break;
1498         default:
1499                 fatal("silly mux_command %d", mux_command);
1500         }
1501
1502         /* SSHMUX_COMMAND_OPEN */
1503         buffer_put_cstring(&m, term ? term : "");
1504         buffer_append(&command, "\0", 1);
1505         buffer_put_cstring(&m, buffer_ptr(&command));
1506
1507         if (options.num_send_env == 0 || environ == NULL) {
1508                 buffer_put_int(&m, 0);
1509         } else {
1510                 /* Pass environment */
1511                 num_env = 0;
1512                 for (i = 0; environ[i] != NULL; i++)
1513                         if (env_permitted(environ[i]))
1514                                 num_env++; /* Count */
1515
1516                 buffer_put_int(&m, num_env);
1517
1518                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1519                         if (env_permitted(environ[i])) {
1520                                 num_env--;
1521                                 buffer_put_cstring(&m, environ[i]);
1522                         }
1523         }
1524
1525         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1526                 fatal("%s: msg_send", __func__);
1527
1528         mm_send_fd(sock, STDIN_FILENO);
1529         mm_send_fd(sock, STDOUT_FILENO);
1530         mm_send_fd(sock, STDERR_FILENO);
1531
1532         /* Wait for reply, so master has a chance to gather ttymodes */
1533         buffer_clear(&m);
1534         if (ssh_msg_recv(sock, &m) == -1)
1535                 fatal("%s: msg_recv", __func__);
1536         if (buffer_get_char(&m) != SSHMUX_VER)
1537                 fatal("%s: wrong version", __func__);
1538         buffer_free(&m);
1539
1540         signal(SIGHUP, control_client_sighandler);
1541         signal(SIGINT, control_client_sighandler);
1542         signal(SIGTERM, control_client_sighandler);
1543         signal(SIGWINCH, control_client_sigrelay);
1544
1545         if (tty_flag)
1546                 enter_raw_mode();
1547
1548         /*
1549          * Stick around until the controlee closes the client_fd.
1550          * Before it does, it is expected to write this process' exit
1551          * value (one int). This process must read the value and wait for
1552          * the closure of the client_fd; if this one closes early, the
1553          * multiplex master will terminate early too (possibly losing data).
1554          */
1555         exitval[0] = 0;
1556         for (i = 0; !control_client_terminate && i < (int)sizeof(exitval);) {
1557                 r = read(sock, (char *)exitval + i, sizeof(exitval) - i);
1558                 if (r == 0) {
1559                         debug2("Received EOF from master");
1560                         break;
1561                 }
1562                 if (r == -1) {
1563                         if (errno == EINTR)
1564                                 continue;
1565                         fatal("%s: read %s", __func__, strerror(errno));
1566                 }
1567                 i += r;
1568         }
1569
1570         close(sock);
1571         leave_raw_mode();
1572         if (i > (int)sizeof(int))
1573                 fatal("%s: master returned too much data (%d > %lu)",
1574                     __func__, i, sizeof(int));
1575         if (control_client_terminate) {
1576                 debug2("Exiting on signal %d", control_client_terminate);
1577                 exitval[0] = 255;
1578         } else if (i < (int)sizeof(int)) {
1579                 debug2("Control master terminated unexpectedly");
1580                 exitval[0] = 255;
1581         } else
1582                 debug2("Received exit status from master %d", exitval[0]);
1583
1584         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1585                 fprintf(stderr, "Shared connection to %s closed.\r\n", host);
1586
1587         exit(exitval[0]);
1588 }