crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.294 2006/10/06 02:29:19 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 __RCSID("$FreeBSD$");
  45
  46 #include <sys/types.h>
  47 #ifdef HAVE_SYS_STAT_H
  48 # include <sys/stat.h>
  49 #endif
  50 #include <sys/resource.h>
  51 #include <sys/ioctl.h>
  52 #include <sys/socket.h>
  53 #include <sys/un.h>
  54
  55 #include <ctype.h>
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #include <netdb.h>
  59 #ifdef HAVE_PATHS_H
  60 #include <paths.h>
  61 #endif
  62 #include <pwd.h>
  63 #include <signal.h>
  64 #include <stdarg.h>
  65 #include <stddef.h>
  66 #include <stdio.h>
  67 #include <stdlib.h>
  68 #include <string.h>
  69 #include <unistd.h>
  70
  71 #include <netinet/in.h>
  72 #include <arpa/inet.h>
  73
  74 #include <openssl/evp.h>
  75 #include <openssl/err.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 [-1246AaCfgkMNnqsTtVvXxY] [-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;
 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:L: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 'i':
 331                         if (stat(optarg, &st) < 0) {
 332                                 fprintf(stderr, "Warning: Identity file %s "
 333                                     "not accessible: %s.\n", optarg,
 334                                     strerror(errno));
 335                                 break;
 336                         }
 337                         if (options.num_identity_files >=
 338                             SSH_MAX_IDENTITY_FILES)
 339                                 fatal("Too many identity files specified "
 340                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 341                         options.identity_files[options.num_identity_files++] =
 342                             xstrdup(optarg);
 343                         break;
 344                 case 'I':
 345 #ifdef SMARTCARD
 346                         options.smartcard_device = xstrdup(optarg);
 347 #else
 348                         fprintf(stderr, "no support for smartcards.\n");
 349 #endif
 350                         break;
 351                 case 't':
 352                         if (tty_flag)
 353                                 force_tty_flag = 1;
 354                         tty_flag = 1;
 355                         break;
 356                 case 'v':
 357                         if (debug_flag == 0) {
 358                                 debug_flag = 1;
 359                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 360                         } else {
 361                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 362                                         options.log_level++;
 363                                 break;
 364                         }
 365                         /* FALLTHROUGH */
 366                 case 'V':
 367                         fprintf(stderr, "%s, %s\n",
 368                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 369                         if (opt == 'V')
 370                                 exit(0);
 371                         break;
 372                 case 'w':
 373                         if (options.tun_open == -1)
 374                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 375                         options.tun_local = a2tun(optarg, &options.tun_remote);
 376                         if (options.tun_local == SSH_TUNID_ERR) {
 377                                 fprintf(stderr, "Bad tun device '%s'\n", optarg);
 378                                 exit(255);
 379                         }
 380                         break;
 381                 case 'q':
 382                         options.log_level = SYSLOG_LEVEL_QUIET;
 383                         break;
 384                 case 'e':
 385                         if (optarg[0] == '^' && optarg[2] == 0 &&
 386                             (u_char) optarg[1] >= 64 &&
 387                             (u_char) optarg[1] < 128)
 388                                 options.escape_char = (u_char) optarg[1] & 31;
 389                         else if (strlen(optarg) == 1)
 390                                 options.escape_char = (u_char) optarg[0];
 391                         else if (strcmp(optarg, "none") == 0)
 392                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 393                         else {
 394                                 fprintf(stderr, "Bad escape character '%s'.\n",
 395                                     optarg);
 396                                 exit(255);
 397                         }
 398                         break;
 399                 case 'c':
 400                         if (ciphers_valid(optarg)) {
 401                                 /* SSH2 only */
 402                                 options.ciphers = xstrdup(optarg);
 403                                 options.cipher = SSH_CIPHER_INVALID;
 404                         } else {
 405                                 /* SSH1 only */
 406                                 options.cipher = cipher_number(optarg);
 407                                 if (options.cipher == -1) {
 408                                         fprintf(stderr,
 409                                             "Unknown cipher type '%s'\n",
 410                                             optarg);
 411                                         exit(255);
 412                                 }
 413                                 if (options.cipher == SSH_CIPHER_3DES)
 414                                         options.ciphers = "3des-cbc";
 415                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 416                                         options.ciphers = "blowfish-cbc";
 417                                 else
 418                                         options.ciphers = (char *)-1;
 419                         }
 420                         break;
 421                 case 'm':
 422                         if (mac_valid(optarg))
 423                                 options.macs = xstrdup(optarg);
 424                         else {
 425                                 fprintf(stderr, "Unknown mac type '%s'\n",
 426                                     optarg);
 427                                 exit(255);
 428                         }
 429                         break;
 430                 case 'M':
 431                         if (options.control_master == SSHCTL_MASTER_YES)
 432                                 options.control_master = SSHCTL_MASTER_ASK;
 433                         else
 434                                 options.control_master = SSHCTL_MASTER_YES;
 435                         break;
 436                 case 'p':
 437                         options.port = a2port(optarg);
 438                         if (options.port == 0) {
 439                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 440                                 exit(255);
 441                         }
 442                         break;
 443                 case 'l':
 444                         options.user = optarg;
 445                         break;
 446
 447                 case 'L':
 448                         if (parse_forward(&fwd, optarg))
 449                                 add_local_forward(&options, &fwd);
 450                         else {
 451                                 fprintf(stderr,
 452                                     "Bad local forwarding specification '%s'\n",
 453                                     optarg);
 454                                 exit(255);
 455                         }
 456                         break;
 457
 458                 case 'R':
 459                         if (parse_forward(&fwd, optarg)) {
 460                                 add_remote_forward(&options, &fwd);
 461                         } else {
 462                                 fprintf(stderr,
 463                                     "Bad remote forwarding specification "
 464                                     "'%s'\n", optarg);
 465                                 exit(255);
 466                         }
 467                         break;
 468
 469                 case 'D':
 470                         cp = p = xstrdup(optarg);
 471                         memset(&fwd, '\0', sizeof(fwd));
 472                         fwd.connect_host = "socks";
 473                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 474                                 fprintf(stderr, "Bad dynamic forwarding "
 475                                     "specification '%.100s'\n", optarg);
 476                                 exit(255);
 477                         }
 478                         if (cp != NULL) {
 479                                 fwd.listen_port = a2port(cp);
 480                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 481                         } else {
 482                                 fwd.listen_port = a2port(fwd.listen_host);
 483                                 fwd.listen_host = NULL;
 484                         }
 485
 486                         if (fwd.listen_port == 0) {
 487                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 488                                     optarg);
 489                                 exit(255);
 490                         }
 491                         add_local_forward(&options, &fwd);
 492                         xfree(p);
 493                         break;
 494
 495                 case 'C':
 496                         options.compression = 1;
 497                         break;
 498                 case 'N':
 499                         no_shell_flag = 1;
 500                         no_tty_flag = 1;
 501                         break;
 502                 case 'T':
 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 's':
 514                         subsystem_flag = 1;
 515                         break;
 516                 case 'S':
 517                         if (options.control_path != NULL)
 518                                 free(options.control_path);
 519                         options.control_path = xstrdup(optarg);
 520                         break;
 521                 case 'b':
 522                         options.bind_address = optarg;
 523                         break;
 524                 case 'F':
 525                         config = optarg;
 526                         break;
 527                 default:
 528                         usage();
 529                 }
 530         }
 531
 532         ac -= optind;
 533         av += optind;
 534
 535         if (ac > 0 && !host && **av != '-') {
 536                 if (strrchr(*av, '@')) {
 537                         p = xstrdup(*av);
 538                         cp = strrchr(p, '@');
 539                         if (cp == NULL || cp == p)
 540                                 usage();
 541                         options.user = p;
 542                         *cp = '\0';
 543                         host = ++cp;
 544                 } else
 545                         host = *av;
 546                 if (ac > 1) {
 547                         optind = optreset = 1;
 548                         goto again;
 549                 }
 550                 ac--, av++;
 551         }
 552
 553         /* Check that we got a host name. */
 554         if (!host)
 555                 usage();
 556
 557         SSLeay_add_all_algorithms();
 558         ERR_load_crypto_strings();
 559
 560         /* Initialize the command to execute on remote host. */
 561         buffer_init(&command);
 562
 563         /*
 564          * Save the command to execute on the remote host in a buffer. There
 565          * is no limit on the length of the command, except by the maximum
 566          * packet size.  Also sets the tty flag if there is no command.
 567          */
 568         if (!ac) {
 569                 /* No command specified - execute shell on a tty. */
 570                 tty_flag = 1;
 571                 if (subsystem_flag) {
 572                         fprintf(stderr,
 573                             "You must specify a subsystem to invoke.\n");
 574                         usage();
 575                 }
 576         } else {
 577                 /* A command has been specified.  Store it into the buffer. */
 578                 for (i = 0; i < ac; i++) {
 579                         if (i)
 580                                 buffer_append(&command, " ", 1);
 581                         buffer_append(&command, av[i], strlen(av[i]));
 582                 }
 583         }
 584
 585         /* Cannot fork to background if no command. */
 586         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 587                 fatal("Cannot fork into background without a command to execute.");
 588
 589         /* Allocate a tty by default if no command specified. */
 590         if (buffer_len(&command) == 0)
 591                 tty_flag = 1;
 592
 593         /* Force no tty */
 594         if (no_tty_flag)
 595                 tty_flag = 0;
 596         /* Do not allocate a tty if stdin is not a tty. */
 597         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 598                 if (tty_flag)
 599                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 600                 tty_flag = 0;
 601         }
 602
 603         /*
 604          * Initialize "log" output.  Since we are the client all output
 605          * actually goes to stderr.
 606          */
 607         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 608             SYSLOG_FACILITY_USER, 1);
 609
 610         /*
 611          * Read per-user configuration file.  Ignore the system wide config
 612          * file if the user specifies a config file on the command line.
 613          */
 614         if (config != NULL) {
 615                 if (!read_config_file(config, host, &options, 0))
 616                         fatal("Can't open user config file %.100s: "
 617                             "%.100s", config, strerror(errno));
 618         } else  {
 619                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 620                     _PATH_SSH_USER_CONFFILE);
 621                 (void)read_config_file(buf, host, &options, 1);
 622
 623                 /* Read systemwide configuration file after use config. */
 624                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 625                     &options, 0);
 626         }
 627
 628         /* Fill configuration defaults. */
 629         fill_default_options(&options);
 630
 631         channel_set_af(options.address_family);
 632
 633         /* reinit */
 634         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 635
 636         seed_rng();
 637
 638         if (options.user == NULL)
 639                 options.user = xstrdup(pw->pw_name);
 640
 641         if (options.hostname != NULL)
 642                 host = options.hostname;
 643
 644         /* Find canonic host name. */
 645         if (strchr(host, '.') == 0) {
 646                 struct addrinfo hints;
 647                 struct addrinfo *ai = NULL;
 648                 int errgai;
 649                 memset(&hints, 0, sizeof(hints));
 650                 hints.ai_family = options.address_family;
 651                 hints.ai_flags = AI_CANONNAME;
 652                 hints.ai_socktype = SOCK_STREAM;
 653                 errgai = getaddrinfo(host, NULL, &hints, &ai);
 654                 if (errgai == 0) {
 655                         if (ai->ai_canonname != NULL)
 656                                 host = xstrdup(ai->ai_canonname);
 657                         freeaddrinfo(ai);
 658                 }
 659         }
 660
 661         /* force lowercase for hostkey matching */
 662         if (options.host_key_alias != NULL) {
 663                 for (p = options.host_key_alias; *p; p++)
 664                         if (isupper(*p))
 665                                 *p = (char)tolower(*p);
 666         }
 667
 668         /* Get default port if port has not been set. */
 669         if (options.port == 0) {
 670                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 671                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 672         }
 673
 674         if (options.proxy_command != NULL &&
 675             strcmp(options.proxy_command, "none") == 0)
 676                 options.proxy_command = NULL;
 677         if (options.control_path != NULL &&
 678             strcmp(options.control_path, "none") == 0)
 679                 options.control_path = NULL;
 680
 681         if (options.control_path != NULL) {
 682                 char thishost[NI_MAXHOST];
 683
 684                 if (gethostname(thishost, sizeof(thishost)) == -1)
 685                         fatal("gethostname: %s", strerror(errno));
 686                 snprintf(buf, sizeof(buf), "%d", options.port);
 687                 cp = tilde_expand_filename(options.control_path,
 688                     original_real_uid);
 689                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 690                     "r", options.user, "l", thishost, (char *)NULL);
 691                 xfree(cp);
 692         }
 693         if (mux_command != 0 && options.control_path == NULL)
 694                 fatal("No ControlPath specified for \"-O\" command");
 695         if (options.control_path != NULL)
 696                 control_client(options.control_path);
 697
 698         /* Open a connection to the remote host. */
 699         if (ssh_connect(host, &hostaddr, options.port,
 700             options.address_family, options.connection_attempts,
 701 #ifdef HAVE_CYGWIN
 702             options.use_privileged_port,
 703 #else
 704             original_effective_uid == 0 && options.use_privileged_port,
 705 #endif
 706             options.proxy_command) != 0)
 707                 exit(255);
 708
 709         /*
 710          * If we successfully made the connection, load the host private key
 711          * in case we will need it later for combined rsa-rhosts
 712          * authentication. This must be done before releasing extra
 713          * privileges, because the file is only readable by root.
 714          * If we cannot access the private keys, load the public keys
 715          * instead and try to execute the ssh-keysign helper instead.
 716          */
 717         sensitive_data.nkeys = 0;
 718         sensitive_data.keys = NULL;
 719         sensitive_data.external_keysign = 0;
 720         if (options.rhosts_rsa_authentication ||
 721             options.hostbased_authentication) {
 722                 sensitive_data.nkeys = 3;
 723                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 724                     sizeof(Key));
 725
 726                 PRIV_START;
 727                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 728                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 729                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 730                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 731                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 732                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 733                 PRIV_END;
 734
 735                 if (options.hostbased_authentication == 1 &&
 736                     sensitive_data.keys[0] == NULL &&
 737                     sensitive_data.keys[1] == NULL &&
 738                     sensitive_data.keys[2] == NULL) {
 739                         sensitive_data.keys[1] = key_load_public(
 740                             _PATH_HOST_DSA_KEY_FILE, NULL);
 741                         sensitive_data.keys[2] = key_load_public(
 742                             _PATH_HOST_RSA_KEY_FILE, NULL);
 743                         sensitive_data.external_keysign = 1;
 744                 }
 745         }
 746         /*
 747          * Get rid of any extra privileges that we may have.  We will no
 748          * longer need them.  Also, extra privileges could make it very hard
 749          * to read identity files and other non-world-readable files from the
 750          * user's home directory if it happens to be on a NFS volume where
 751          * root is mapped to nobody.
 752          */
 753         if (original_effective_uid == 0) {
 754                 PRIV_START;
 755                 permanently_set_uid(pw);
 756         }
 757
 758         /*
 759          * Now that we are back to our own permissions, create ~/.ssh
 760          * directory if it doesn't already exist.
 761          */
 762         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 763         if (stat(buf, &st) < 0)
 764                 if (mkdir(buf, 0700) < 0)
 765                         error("Could not create directory '%.200s'.", buf);
 766
 767         /* load options.identity_files */
 768         load_public_identity_files();
 769
 770         /* Expand ~ in known host file names. */
 771         /* XXX mem-leaks: */
 772         options.system_hostfile =
 773             tilde_expand_filename(options.system_hostfile, original_real_uid);
 774         options.user_hostfile =
 775             tilde_expand_filename(options.user_hostfile, original_real_uid);
 776         options.system_hostfile2 =
 777             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 778         options.user_hostfile2 =
 779             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 780
 781         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 782
 783         /* Log into the remote system.  This never returns if the login fails. */
 784         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 785
 786         /* We no longer need the private host keys.  Clear them now. */
 787         if (sensitive_data.nkeys != 0) {
 788                 for (i = 0; i < sensitive_data.nkeys; i++) {
 789                         if (sensitive_data.keys[i] != NULL) {
 790                                 /* Destroys contents safely */
 791                                 debug3("clear hostkey %d", i);
 792                                 key_free(sensitive_data.keys[i]);
 793                                 sensitive_data.keys[i] = NULL;
 794                         }
 795                 }
 796                 xfree(sensitive_data.keys);
 797         }
 798         for (i = 0; i < options.num_identity_files; i++) {
 799                 if (options.identity_files[i]) {
 800                         xfree(options.identity_files[i]);
 801                         options.identity_files[i] = NULL;
 802                 }
 803                 if (options.identity_keys[i]) {
 804                         key_free(options.identity_keys[i]);
 805                         options.identity_keys[i] = NULL;
 806                 }
 807         }
 808
 809         exit_status = compat20 ? ssh_session2() : ssh_session();
 810         packet_close();
 811
 812         if (options.control_path != NULL && control_fd != -1)
 813                 unlink(options.control_path);
 814
 815         /*
 816          * Send SIGHUP to proxy command if used. We don't wait() in
 817          * case it hangs and instead rely on init to reap the child
 818          */
 819         if (proxy_command_pid > 1)
 820                 kill(proxy_command_pid, SIGHUP);
 821
 822         return exit_status;
 823 }
 824
 825 static void
 826 ssh_init_forwarding(void)
 827 {
 828         int success = 0;
 829         int i;
 830
 831         /* Initiate local TCP/IP port forwardings. */
 832         for (i = 0; i < options.num_local_forwards; i++) {
 833                 debug("Local connections to %.200s:%d forwarded to remote "
 834                     "address %.200s:%d",
 835                     (options.local_forwards[i].listen_host == NULL) ?
 836                     (options.gateway_ports ? "*" : "LOCALHOST") :
 837                     options.local_forwards[i].listen_host,
 838                     options.local_forwards[i].listen_port,
 839                     options.local_forwards[i].connect_host,
 840                     options.local_forwards[i].connect_port);
 841                 success += channel_setup_local_fwd_listener(
 842                     options.local_forwards[i].listen_host,
 843                     options.local_forwards[i].listen_port,
 844                     options.local_forwards[i].connect_host,
 845                     options.local_forwards[i].connect_port,
 846                     options.gateway_ports);
 847         }
 848         if (i > 0 && success != i && options.exit_on_forward_failure)
 849                 fatal("Could not request local forwarding.");
 850         if (i > 0 && success == 0)
 851                 error("Could not request local forwarding.");
 852
 853         /* Initiate remote TCP/IP port forwardings. */
 854         for (i = 0; i < options.num_remote_forwards; i++) {
 855                 debug("Remote connections from %.200s:%d forwarded to "
 856                     "local address %.200s:%d",
 857                     (options.remote_forwards[i].listen_host == NULL) ?
 858                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 859                     options.remote_forwards[i].listen_port,
 860                     options.remote_forwards[i].connect_host,
 861                     options.remote_forwards[i].connect_port);
 862                 if (channel_request_remote_forwarding(
 863                     options.remote_forwards[i].listen_host,
 864                     options.remote_forwards[i].listen_port,
 865                     options.remote_forwards[i].connect_host,
 866                     options.remote_forwards[i].connect_port) < 0) {
 867                         if (options.exit_on_forward_failure)
 868                                 fatal("Could not request remote forwarding.");
 869                         else
 870                                 logit("Warning: Could not request remote "
 871                                     "forwarding.");
 872                 }
 873         }
 874 }
 875
 876 static void
 877 check_agent_present(void)
 878 {
 879         if (options.forward_agent) {
 880                 /* Clear agent forwarding if we don't have an agent. */
 881                 if (!ssh_agent_present())
 882                         options.forward_agent = 0;
 883         }
 884 }
 885
 886 static int
 887 ssh_session(void)
 888 {
 889         int type;
 890         int interactive = 0;
 891         int have_tty = 0;
 892         struct winsize ws;
 893         char *cp;
 894         const char *display;
 895
 896         /* Enable compression if requested. */
 897         if (options.compression) {
 898                 debug("Requesting compression at level %d.", options.compression_level);
 899
 900                 if (options.compression_level < 1 || options.compression_level > 9)
 901                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 902
 903                 /* Send the request. */
 904                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 905                 packet_put_int(options.compression_level);
 906                 packet_send();
 907                 packet_write_wait();
 908                 type = packet_read();
 909                 if (type == SSH_SMSG_SUCCESS)
 910                         packet_start_compression(options.compression_level);
 911                 else if (type == SSH_SMSG_FAILURE)
 912                         logit("Warning: Remote host refused compression.");
 913                 else
 914                         packet_disconnect("Protocol error waiting for compression response.");
 915         }
 916         /* Allocate a pseudo tty if appropriate. */
 917         if (tty_flag) {
 918                 debug("Requesting pty.");
 919
 920                 /* Start the packet. */
 921                 packet_start(SSH_CMSG_REQUEST_PTY);
 922
 923                 /* Store TERM in the packet.  There is no limit on the
 924                    length of the string. */
 925                 cp = getenv("TERM");
 926                 if (!cp)
 927                         cp = "";
 928                 packet_put_cstring(cp);
 929
 930                 /* Store window size in the packet. */
 931                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 932                         memset(&ws, 0, sizeof(ws));
 933                 packet_put_int((u_int)ws.ws_row);
 934                 packet_put_int((u_int)ws.ws_col);
 935                 packet_put_int((u_int)ws.ws_xpixel);
 936                 packet_put_int((u_int)ws.ws_ypixel);
 937
 938                 /* Store tty modes in the packet. */
 939                 tty_make_modes(fileno(stdin), NULL);
 940
 941                 /* Send the packet, and wait for it to leave. */
 942                 packet_send();
 943                 packet_write_wait();
 944
 945                 /* Read response from the server. */
 946                 type = packet_read();
 947                 if (type == SSH_SMSG_SUCCESS) {
 948                         interactive = 1;
 949                         have_tty = 1;
 950                 } else if (type == SSH_SMSG_FAILURE)
 951                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 952                 else
 953                         packet_disconnect("Protocol error waiting for pty request response.");
 954         }
 955         /* Request X11 forwarding if enabled and DISPLAY is set. */
 956         display = getenv("DISPLAY");
 957         if (options.forward_x11 && display != NULL) {
 958                 char *proto, *data;
 959                 /* Get reasonable local authentication information. */
 960                 client_x11_get_proto(display, options.xauth_location,
 961                     options.forward_x11_trusted, &proto, &data);
 962                 /* Request forwarding with authentication spoofing. */
 963                 debug("Requesting X11 forwarding with authentication spoofing.");
 964                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 965
 966                 /* Read response from the server. */
 967                 type = packet_read();
 968                 if (type == SSH_SMSG_SUCCESS) {
 969                         interactive = 1;
 970                 } else if (type == SSH_SMSG_FAILURE) {
 971                         logit("Warning: Remote host denied X11 forwarding.");
 972                 } else {
 973                         packet_disconnect("Protocol error waiting for X11 forwarding");
 974                 }
 975         }
 976         /* Tell the packet module whether this is an interactive session. */
 977         packet_set_interactive(interactive);
 978
 979         /* Request authentication agent forwarding if appropriate. */
 980         check_agent_present();
 981
 982         if (options.forward_agent) {
 983                 debug("Requesting authentication agent forwarding.");
 984                 auth_request_forwarding();
 985
 986                 /* Read response from the server. */
 987                 type = packet_read();
 988                 packet_check_eom();
 989                 if (type != SSH_SMSG_SUCCESS)
 990                         logit("Warning: Remote host denied authentication agent forwarding.");
 991         }
 992
 993         /* Initiate port forwardings. */
 994         ssh_init_forwarding();
 995
 996         /* If requested, let ssh continue in the background. */
 997         if (fork_after_authentication_flag)
 998                 if (daemon(1, 1) < 0)
 999                         fatal("daemon() failed: %.200s", strerror(errno));
1000
1001         /*
1002          * If a command was specified on the command line, execute the
1003          * command now. Otherwise request the server to start a shell.
1004          */
1005         if (buffer_len(&command) > 0) {
1006                 int len = buffer_len(&command);
1007                 if (len > 900)
1008                         len = 900;
1009                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1010                 packet_start(SSH_CMSG_EXEC_CMD);
1011                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1012                 packet_send();
1013                 packet_write_wait();
1014         } else {
1015                 debug("Requesting shell.");
1016                 packet_start(SSH_CMSG_EXEC_SHELL);
1017                 packet_send();
1018                 packet_write_wait();
1019         }
1020
1021         /* Enter the interactive session. */
1022         return client_loop(have_tty, tty_flag ?
1023             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1024 }
1025
1026 static void
1027 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1028 {
1029         int id, len;
1030
1031         id = packet_get_int();
1032         len = buffer_len(&command);
1033         if (len > 900)
1034                 len = 900;
1035         packet_check_eom();
1036         if (type == SSH2_MSG_CHANNEL_FAILURE)
1037                 fatal("Request for subsystem '%.*s' failed on channel %d",
1038                     len, (u_char *)buffer_ptr(&command), id);
1039 }
1040
1041 void
1042 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1043 {
1044         int i;
1045
1046         i = client_global_request_id++;
1047         if (i >= options.num_remote_forwards)
1048                 return;
1049         debug("remote forward %s for: listen %d, connect %s:%d",
1050             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1051             options.remote_forwards[i].listen_port,
1052             options.remote_forwards[i].connect_host,
1053             options.remote_forwards[i].connect_port);
1054         if (type == SSH2_MSG_REQUEST_FAILURE) {
1055                 if (options.exit_on_forward_failure)
1056                         fatal("Error: remote port forwarding failed for "
1057                             "listen port %d",
1058                             options.remote_forwards[i].listen_port);
1059                 else
1060                         logit("Warning: remote port forwarding failed for "
1061                             "listen port %d",
1062                             options.remote_forwards[i].listen_port);
1063         }
1064 }
1065
1066 static void
1067 ssh_control_listener(void)
1068 {
1069         struct sockaddr_un addr;
1070         mode_t old_umask;
1071         int addr_len;
1072
1073         if (options.control_path == NULL ||
1074             options.control_master == SSHCTL_MASTER_NO)
1075                 return;
1076
1077         debug("setting up multiplex master socket");
1078
1079         memset(&addr, '\0', sizeof(addr));
1080         addr.sun_family = AF_UNIX;
1081         addr_len = offsetof(struct sockaddr_un, sun_path) +
1082             strlen(options.control_path) + 1;
1083
1084         if (strlcpy(addr.sun_path, options.control_path,
1085             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1086                 fatal("ControlPath too long");
1087
1088         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1089                 fatal("%s socket(): %s", __func__, strerror(errno));
1090
1091         old_umask = umask(0177);
1092         if (bind(control_fd, (struct sockaddr *)&addr, addr_len) == -1) {
1093                 control_fd = -1;
1094                 if (errno == EINVAL || errno == EADDRINUSE)
1095                         fatal("ControlSocket %s already exists",
1096                             options.control_path);
1097                 else
1098                         fatal("%s bind(): %s", __func__, strerror(errno));
1099         }
1100         umask(old_umask);
1101
1102         if (listen(control_fd, 64) == -1)
1103                 fatal("%s listen(): %s", __func__, strerror(errno));
1104
1105         set_nonblock(control_fd);
1106 }
1107
1108 /* request pty/x11/agent/tcpfwd/shell for channel */
1109 static void
1110 ssh_session2_setup(int id, void *arg)
1111 {
1112         extern char **environ;
1113         const char *display;
1114         int interactive = tty_flag;
1115
1116         display = getenv("DISPLAY");
1117         if (options.forward_x11 && display != NULL) {
1118                 char *proto, *data;
1119                 /* Get reasonable local authentication information. */
1120                 client_x11_get_proto(display, options.xauth_location,
1121                     options.forward_x11_trusted, &proto, &data);
1122                 /* Request forwarding with authentication spoofing. */
1123                 debug("Requesting X11 forwarding with authentication spoofing.");
1124                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1125                 interactive = 1;
1126                 /* XXX wait for reply */
1127         }
1128
1129         check_agent_present();
1130         if (options.forward_agent) {
1131                 debug("Requesting authentication agent forwarding.");
1132                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1133                 packet_send();
1134         }
1135
1136         if (options.tun_open != SSH_TUNMODE_NO) {
1137                 Channel *c;
1138                 int fd;
1139
1140                 debug("Requesting tun.");
1141                 if ((fd = tun_open(options.tun_local,
1142                     options.tun_open)) >= 0) {
1143                         c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
1144                             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1145                             0, "tun", 1);
1146                         c->datagram = 1;
1147 #if defined(SSH_TUN_FILTER)
1148                         if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
1149                                 channel_register_filter(c->self, sys_tun_infilter,
1150                                     sys_tun_outfilter);
1151 #endif
1152                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1153                         packet_put_cstring("tun@openssh.com");
1154                         packet_put_int(c->self);
1155                         packet_put_int(c->local_window_max);
1156                         packet_put_int(c->local_maxpacket);
1157                         packet_put_int(options.tun_open);
1158                         packet_put_int(options.tun_remote);
1159                         packet_send();
1160                 }
1161         }
1162
1163         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1164             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1165
1166         packet_set_interactive(interactive);
1167 }
1168
1169 /* open new channel for a session */
1170 static int
1171 ssh_session2_open(void)
1172 {
1173         Channel *c;
1174         int window, packetmax, in, out, err;
1175
1176         if (stdin_null_flag) {
1177                 in = open(_PATH_DEVNULL, O_RDONLY);
1178         } else {
1179                 in = dup(STDIN_FILENO);
1180         }
1181         out = dup(STDOUT_FILENO);
1182         err = dup(STDERR_FILENO);
1183
1184         if (in < 0 || out < 0 || err < 0)
1185                 fatal("dup() in/out/err failed");
1186
1187         /* enable nonblocking unless tty */
1188         if (!isatty(in))
1189                 set_nonblock(in);
1190         if (!isatty(out))
1191                 set_nonblock(out);
1192         if (!isatty(err))
1193                 set_nonblock(err);
1194
1195         window = CHAN_SES_WINDOW_DEFAULT;
1196         packetmax = CHAN_SES_PACKET_DEFAULT;
1197         if (tty_flag) {
1198                 window >>= 1;
1199                 packetmax >>= 1;
1200         }
1201         c = channel_new(
1202             "session", SSH_CHANNEL_OPENING, in, out, err,
1203             window, packetmax, CHAN_EXTENDED_WRITE,
1204             "client-session", /*nonblock*/0);
1205
1206         debug3("ssh_session2_open: channel_new: %d", c->self);
1207
1208         channel_send_open(c->self);
1209         if (!no_shell_flag)
1210                 channel_register_confirm(c->self, ssh_session2_setup, NULL);
1211
1212         return c->self;
1213 }
1214
1215 static int
1216 ssh_session2(void)
1217 {
1218         int id = -1;
1219
1220         /* XXX should be pre-session */
1221         ssh_init_forwarding();
1222         ssh_control_listener();
1223
1224         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1225                 id = ssh_session2_open();
1226
1227         /* Execute a local command */
1228         if (options.local_command != NULL &&
1229             options.permit_local_command)
1230                 ssh_local_cmd(options.local_command);
1231
1232         /* If requested, let ssh continue in the background. */
1233         if (fork_after_authentication_flag)
1234                 if (daemon(1, 1) < 0)
1235                         fatal("daemon() failed: %.200s", strerror(errno));
1236
1237         return client_loop(tty_flag, tty_flag ?
1238             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1239 }
1240
1241 static void
1242 load_public_identity_files(void)
1243 {
1244         char *filename, *cp, thishost[NI_MAXHOST];
1245         int i = 0;
1246         Key *public;
1247         struct passwd *pw;
1248 #ifdef SMARTCARD
1249         Key **keys;
1250
1251         if (options.smartcard_device != NULL &&
1252             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1253             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL) {
1254                 int count = 0;
1255                 for (i = 0; keys[i] != NULL; i++) {
1256                         count++;
1257                         memmove(&options.identity_files[1], &options.identity_files[0],
1258                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1259                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1260                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1261                         options.num_identity_files++;
1262                         options.identity_keys[0] = keys[i];
1263                         options.identity_files[0] = sc_get_key_label(keys[i]);
1264                 }
1265                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1266                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1267                 i = count;
1268                 xfree(keys);
1269         }
1270 #endif /* SMARTCARD */
1271         if ((pw = getpwuid(original_real_uid)) == NULL)
1272                 fatal("load_public_identity_files: getpwuid failed");
1273         if (gethostname(thishost, sizeof(thishost)) == -1)
1274                 fatal("load_public_identity_files: gethostname: %s",
1275                     strerror(errno));
1276         for (; i < options.num_identity_files; i++) {
1277                 cp = tilde_expand_filename(options.identity_files[i],
1278                     original_real_uid);
1279                 filename = percent_expand(cp, "d", pw->pw_dir,
1280                     "u", pw->pw_name, "l", thishost, "h", host,
1281                     "r", options.user, (char *)NULL);
1282                 xfree(cp);
1283                 public = key_load_public(filename, NULL);
1284                 debug("identity file %s type %d", filename,
1285                     public ? public->type : -1);
1286                 xfree(options.identity_files[i]);
1287                 options.identity_files[i] = filename;
1288                 options.identity_keys[i] = public;
1289         }
1290 }
1291
1292 static void
1293 control_client_sighandler(int signo)
1294 {
1295         control_client_terminate = signo;
1296 }
1297
1298 static void
1299 control_client_sigrelay(int signo)
1300 {
1301         if (control_server_pid > 1)
1302                 kill(control_server_pid, signo);
1303 }
1304
1305 static int
1306 env_permitted(char *env)
1307 {
1308         int i, ret;
1309         char name[1024], *cp;
1310
1311         if ((cp = strchr(env, '=')) == NULL || cp == env)
1312                 return (0);
1313         ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
1314         if (ret <= 0 || (size_t)ret >= sizeof(name))
1315                 fatal("env_permitted: name '%.100s...' too long", env);
1316
1317         for (i = 0; i < options.num_send_env; i++)
1318                 if (match_pattern(name, options.send_env[i]))
1319                         return (1);
1320
1321         return (0);
1322 }
1323
1324 static void
1325 control_client(const char *path)
1326 {
1327         struct sockaddr_un addr;
1328         int i, r, fd, sock, exitval, num_env, addr_len;
1329         Buffer m;
1330         char *term;
1331         extern char **environ;
1332         u_int  flags;
1333
1334         if (mux_command == 0)
1335                 mux_command = SSHMUX_COMMAND_OPEN;
1336
1337         switch (options.control_master) {
1338         case SSHCTL_MASTER_AUTO:
1339         case SSHCTL_MASTER_AUTO_ASK:
1340                 debug("auto-mux: Trying existing master");
1341                 /* FALLTHROUGH */
1342         case SSHCTL_MASTER_NO:
1343                 break;
1344         default:
1345                 return;
1346         }
1347
1348         memset(&addr, '\0', sizeof(addr));
1349         addr.sun_family = AF_UNIX;
1350         addr_len = offsetof(struct sockaddr_un, sun_path) +
1351             strlen(path) + 1;
1352
1353         if (strlcpy(addr.sun_path, path,
1354             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1355                 fatal("ControlPath too long");
1356
1357         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1358                 fatal("%s socket(): %s", __func__, strerror(errno));
1359
1360         if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) {
1361                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1362                         fatal("Control socket connect(%.100s): %s", path,
1363                             strerror(errno));
1364                 }
1365                 if (errno == ENOENT)
1366                         debug("Control socket \"%.100s\" does not exist", path);
1367                 else {
1368                         error("Control socket connect(%.100s): %s", path,
1369                             strerror(errno));
1370                 }
1371                 close(sock);
1372                 return;
1373         }
1374
1375         if (stdin_null_flag) {
1376                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1377                         fatal("open(/dev/null): %s", strerror(errno));
1378                 if (dup2(fd, STDIN_FILENO) == -1)
1379                         fatal("dup2: %s", strerror(errno));
1380                 if (fd > STDERR_FILENO)
1381                         close(fd);
1382         }
1383
1384         term = getenv("TERM");
1385
1386         flags = 0;
1387         if (tty_flag)
1388                 flags |= SSHMUX_FLAG_TTY;
1389         if (subsystem_flag)
1390                 flags |= SSHMUX_FLAG_SUBSYS;
1391         if (options.forward_x11)
1392                 flags |= SSHMUX_FLAG_X11_FWD;
1393         if (options.forward_agent)
1394                 flags |= SSHMUX_FLAG_AGENT_FWD;
1395
1396         buffer_init(&m);
1397
1398         /* Send our command to server */
1399         buffer_put_int(&m, mux_command);
1400         buffer_put_int(&m, flags);
1401         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1402                 fatal("%s: msg_send", __func__);
1403         buffer_clear(&m);
1404
1405         /* Get authorisation status and PID of controlee */
1406         if (ssh_msg_recv(sock, &m) == -1)
1407                 fatal("%s: msg_recv", __func__);
1408         if (buffer_get_char(&m) != SSHMUX_VER)
1409                 fatal("%s: wrong version", __func__);
1410         if (buffer_get_int(&m) != 1)
1411                 fatal("Connection to master denied");
1412         control_server_pid = buffer_get_int(&m);
1413
1414         buffer_clear(&m);
1415
1416         switch (mux_command) {
1417         case SSHMUX_COMMAND_ALIVE_CHECK:
1418                 fprintf(stderr, "Master running (pid=%d)\r\n",
1419                     control_server_pid);
1420                 exit(0);
1421         case SSHMUX_COMMAND_TERMINATE:
1422                 fprintf(stderr, "Exit request sent.\r\n");
1423                 exit(0);
1424         case SSHMUX_COMMAND_OPEN:
1425                 /* continue below */
1426                 break;
1427         default:
1428                 fatal("silly mux_command %d", mux_command);
1429         }
1430
1431         /* SSHMUX_COMMAND_OPEN */
1432         buffer_put_cstring(&m, term ? term : "");
1433         buffer_append(&command, "\0", 1);
1434         buffer_put_cstring(&m, buffer_ptr(&command));
1435
1436         if (options.num_send_env == 0 || environ == NULL) {
1437                 buffer_put_int(&m, 0);
1438         } else {
1439                 /* Pass environment */
1440                 num_env = 0;
1441                 for (i = 0; environ[i] != NULL; i++)
1442                         if (env_permitted(environ[i]))
1443                                 num_env++; /* Count */
1444
1445                 buffer_put_int(&m, num_env);
1446
1447                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1448                         if (env_permitted(environ[i])) {
1449                                 num_env--;
1450                                 buffer_put_cstring(&m, environ[i]);
1451                         }
1452         }
1453
1454         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1455                 fatal("%s: msg_send", __func__);
1456
1457         mm_send_fd(sock, STDIN_FILENO);
1458         mm_send_fd(sock, STDOUT_FILENO);
1459         mm_send_fd(sock, STDERR_FILENO);
1460
1461         /* Wait for reply, so master has a chance to gather ttymodes */
1462         buffer_clear(&m);
1463         if (ssh_msg_recv(sock, &m) == -1)
1464                 fatal("%s: msg_recv", __func__);
1465         if (buffer_get_char(&m) != SSHMUX_VER)
1466                 fatal("%s: wrong version", __func__);
1467         buffer_free(&m);
1468
1469         signal(SIGHUP, control_client_sighandler);
1470         signal(SIGINT, control_client_sighandler);
1471         signal(SIGTERM, control_client_sighandler);
1472         signal(SIGWINCH, control_client_sigrelay);
1473
1474         if (tty_flag)
1475                 enter_raw_mode();
1476
1477         /* Stick around until the controlee closes the client_fd */
1478         exitval = 0;
1479         for (;!control_client_terminate;) {
1480                 r = read(sock, &exitval, sizeof(exitval));
1481                 if (r == 0) {
1482                         debug2("Received EOF from master");
1483                         break;
1484                 }
1485                 if (r > 0)
1486                         debug2("Received exit status from master %d", exitval);
1487                 if (r == -1 && errno != EINTR)
1488                         fatal("%s: read %s", __func__, strerror(errno));
1489         }
1490
1491         if (control_client_terminate)
1492                 debug2("Exiting on signal %d", control_client_terminate);
1493
1494         close(sock);
1495
1496         leave_raw_mode();
1497
1498         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1499                 fprintf(stderr, "Connection to master closed.\r\n");
1500
1501         exit(exitval);
1502 }