ssh.c

   1 /* $OpenBSD: ssh.c,v 1.310 2008/05/08 12:02:23 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * Ssh client program.  This program can be used to log into a remote machine.
   7  * The software supports strong authentication, encryption, and forwarding
   8  * of X11, TCP/IP, and authentication connections.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  17  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  18  *
  19  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  20  * in Canada (German citizen).
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the above copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  *
  31  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  32  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  34  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  35  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  36  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  37  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  38  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  39  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  40  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  41  */
  42
  43 #include "includes.h"
  44
  45 #include <sys/types.h>
  46 #ifdef HAVE_SYS_STAT_H
  47 # include <sys/stat.h>
  48 #endif
  49 #include <sys/resource.h>
  50 #include <sys/ioctl.h>
  51 #include <sys/socket.h>
  52 #include <sys/un.h>
  53
  54 #include <ctype.h>
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #include <netdb.h>
  58 #ifdef HAVE_PATHS_H
  59 #include <paths.h>
  60 #endif
  61 #include <pwd.h>
  62 #include <signal.h>
  63 #include <stdarg.h>
  64 #include <stddef.h>
  65 #include <stdio.h>
  66 #include <stdlib.h>
  67 #include <string.h>
  68 #include <unistd.h>
  69
  70 #include <netinet/in.h>
  71 #include <arpa/inet.h>
  72
  73 #include <openssl/evp.h>
  74 #include <openssl/err.h>
  75 #include "openbsd-compat/openssl-compat.h"
  76 #include "openbsd-compat/sys-queue.h"
  77
  78 #include "xmalloc.h"
  79 #include "ssh.h"
  80 #include "ssh1.h"
  81 #include "ssh2.h"
  82 #include "compat.h"
  83 #include "cipher.h"
  84 #include "packet.h"
  85 #include "buffer.h"
  86 #include "channels.h"
  87 #include "key.h"
  88 #include "authfd.h"
  89 #include "authfile.h"
  90 #include "pathnames.h"
  91 #include "dispatch.h"
  92 #include "clientloop.h"
  93 #include "log.h"
  94 #include "readconf.h"
  95 #include "sshconnect.h"
  96 #include "misc.h"
  97 #include "kex.h"
  98 #include "mac.h"
  99 #include "sshpty.h"
 100 #include "match.h"
 101 #include "msg.h"
 102 #include "monitor_fdpass.h"
 103 #include "uidswap.h"
 104 #include "version.h"
 105
 106 #ifdef SMARTCARD
 107 #include "scard.h"
 108 #endif
 109
 110 extern char *__progname;
 111
 112 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
 113 int debug_flag = 0;
 114
 115 /* Flag indicating whether a tty should be allocated */
 116 int tty_flag = 0;
 117 int no_tty_flag = 0;
 118 int force_tty_flag = 0;
 119
 120 /* don't exec a shell */
 121 int no_shell_flag = 0;
 122
 123 /*
 124  * Flag indicating that nothing should be read from stdin.  This can be set
 125  * on the command line.
 126  */
 127 int stdin_null_flag = 0;
 128
 129 /*
 130  * Flag indicating that ssh should fork after authentication.  This is useful
 131  * so that the passphrase can be entered manually, and then ssh goes to the
 132  * background.
 133  */
 134 int fork_after_authentication_flag = 0;
 135
 136 /*
 137  * General data structure for command line options and options configurable
 138  * in configuration files.  See readconf.h.
 139  */
 140 Options options;
 141
 142 /* optional user configfile */
 143 char *config = NULL;
 144
 145 /*
 146  * Name of the host we are connecting to.  This is the name given on the
 147  * command line, or the HostName specified for the user-supplied name in a
 148  * configuration file.
 149  */
 150 char *host;
 151
 152 /* socket address the host resolves to */
 153 struct sockaddr_storage hostaddr;
 154
 155 /* Private host keys. */
 156 Sensitive sensitive_data;
 157
 158 /* Original real UID. */
 159 uid_t original_real_uid;
 160 uid_t original_effective_uid;
 161
 162 /* command to be executed */
 163 Buffer command;
 164
 165 /* Should we execute a command or invoke a subsystem? */
 166 int subsystem_flag = 0;
 167
 168 /* # of replies received for global requests */
 169 static int client_global_request_id = 0;
 170
 171 /* pid of proxycommand child process */
 172 pid_t proxy_command_pid = 0;
 173
 174 /* fd to control socket */
 175 int control_fd = -1;
 176
 177 /* Multiplexing control command */
 178 static u_int mux_command = 0;
 179
 180 /* Only used in control client mode */
 181 volatile sig_atomic_t control_client_terminate = 0;
 182 u_int control_server_pid = 0;
 183
 184 /* Prints a help message to the user.  This function never returns. */
 185
 186 static void
 187 usage(void)
 188 {
 189         fprintf(stderr,
 190 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 191 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 192 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 193 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 194 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 195 "           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
 196         );
 197         exit(255);
 198 }
 199
 200 static int ssh_session(void);
 201 static int ssh_session2(void);
 202 static void load_public_identity_files(void);
 203 static void control_client(const char *path);
 204
 205 /*
 206  * Main program for the ssh client.
 207  */
 208 int
 209 main(int ac, char **av)
 210 {
 211         int i, opt, exit_status;
 212         char *p, *cp, *line, buf[256];
 213         struct stat st;
 214         struct passwd *pw;
 215         int dummy, timeout_ms;
 216         extern int optind, optreset;
 217         extern char *optarg;
 218         struct servent *sp;
 219         Forward fwd;
 220
 221         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 222         sanitise_stdfd();
 223
 224         __progname = ssh_get_progname(av[0]);
 225         init_rng();
 226
 227         /*
 228          * Save the original real uid.  It will be needed later (uid-swapping
 229          * may clobber the real uid).
 230          */
 231         original_real_uid = getuid();
 232         original_effective_uid = geteuid();
 233
 234         /*
 235          * Use uid-swapping to give up root privileges for the duration of
 236          * option processing.  We will re-instantiate the rights when we are
 237          * ready to create the privileged port, and will permanently drop
 238          * them when the port has been created (actually, when the connection
 239          * has been made, as we may need to create the port several times).
 240          */
 241         PRIV_END;
 242
 243 #ifdef HAVE_SETRLIMIT
 244         /* If we are installed setuid root be careful to not drop core. */
 245         if (original_real_uid != original_effective_uid) {
 246                 struct rlimit rlim;
 247                 rlim.rlim_cur = rlim.rlim_max = 0;
 248                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 249                         fatal("setrlimit failed: %.100s", strerror(errno));
 250         }
 251 #endif
 252         /* Get user data. */
 253         pw = getpwuid(original_real_uid);
 254         if (!pw) {
 255                 logit("You don't exist, go away!");
 256                 exit(255);
 257         }
 258         /* Take a copy of the returned structure. */
 259         pw = pwcopy(pw);
 260
 261         /*
 262          * Set our umask to something reasonable, as some files are created
 263          * with the default umask.  This will make them world-readable but
 264          * writable only by the owner, which is ok for all files for which we
 265          * don't set the modes explicitly.
 266          */
 267         umask(022);
 268
 269         /* Initialize option structure to indicate that no values have been set. */
 270         initialize_options(&options);
 271
 272         /* Parse command-line arguments. */
 273         host = NULL;
 274
 275  again:
 276         while ((opt = getopt(ac, av,
 277             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:KL:MNO:PR:S:TVw:XY")) != -1) {
 278                 switch (opt) {
 279                 case '1':
 280                         options.protocol = SSH_PROTO_1;
 281                         break;
 282                 case '2':
 283                         options.protocol = SSH_PROTO_2;
 284                         break;
 285                 case '4':
 286                         options.address_family = AF_INET;
 287                         break;
 288                 case '6':
 289                         options.address_family = AF_INET6;
 290                         break;
 291                 case 'n':
 292                         stdin_null_flag = 1;
 293                         break;
 294                 case 'f':
 295                         fork_after_authentication_flag = 1;
 296                         stdin_null_flag = 1;
 297                         break;
 298                 case 'x':
 299                         options.forward_x11 = 0;
 300                         break;
 301                 case 'X':
 302                         options.forward_x11 = 1;
 303                         break;
 304                 case 'Y':
 305                         options.forward_x11 = 1;
 306                         options.forward_x11_trusted = 1;
 307                         break;
 308                 case 'g':
 309                         options.gateway_ports = 1;
 310                         break;
 311                 case 'O':
 312                         if (strcmp(optarg, "check") == 0)
 313                                 mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
 314                         else if (strcmp(optarg, "exit") == 0)
 315                                 mux_command = SSHMUX_COMMAND_TERMINATE;
 316                         else
 317                                 fatal("Invalid multiplex command.");
 318                         break;
 319                 case 'P':       /* deprecated */
 320                         options.use_privileged_port = 0;
 321                         break;
 322                 case 'a':
 323                         options.forward_agent = 0;
 324                         break;
 325                 case 'A':
 326                         options.forward_agent = 1;
 327                         break;
 328                 case 'k':
 329                         options.gss_deleg_creds = 0;
 330                         break;
 331                 case 'K':
 332                         options.gss_authentication = 1;
 333                         options.gss_deleg_creds = 1;
 334                         break;
 335                 case 'i':
 336                         if (stat(optarg, &st) < 0) {
 337                                 fprintf(stderr, "Warning: Identity file %s "
 338                                     "not accessible: %s.\n", optarg,
 339                                     strerror(errno));
 340                                 break;
 341                         }
 342                         if (options.num_identity_files >=
 343                             SSH_MAX_IDENTITY_FILES)
 344                                 fatal("Too many identity files specified "
 345                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 346                         options.identity_files[options.num_identity_files++] =
 347                             xstrdup(optarg);
 348                         break;
 349                 case 'I':
 350 #ifdef SMARTCARD
 351                         options.smartcard_device = xstrdup(optarg);
 352 #else
 353                         fprintf(stderr, "no support for smartcards.\n");
 354 #endif
 355                         break;
 356                 case 't':
 357                         if (tty_flag)
 358                                 force_tty_flag = 1;
 359                         tty_flag = 1;
 360                         break;
 361                 case 'v':
 362                         if (debug_flag == 0) {
 363                                 debug_flag = 1;
 364                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 365                         } else {
 366                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 367                                         options.log_level++;
 368                                 break;
 369                         }
 370                         /* FALLTHROUGH */
 371                 case 'V':
 372                         fprintf(stderr, "%s, %s\n",
 373                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 374                         if (opt == 'V')
 375                                 exit(0);
 376                         break;
 377                 case 'w':
 378                         if (options.tun_open == -1)
 379                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 380                         options.tun_local = a2tun(optarg, &options.tun_remote);
 381                         if (options.tun_local == SSH_TUNID_ERR) {
 382                                 fprintf(stderr, "Bad tun device '%s'\n", optarg);
 383                                 exit(255);
 384                         }
 385                         break;
 386                 case 'q':
 387                         options.log_level = SYSLOG_LEVEL_QUIET;
 388                         break;
 389                 case 'e':
 390                         if (optarg[0] == '^' && optarg[2] == 0 &&
 391                             (u_char) optarg[1] >= 64 &&
 392                             (u_char) optarg[1] < 128)
 393                                 options.escape_char = (u_char) optarg[1] & 31;
 394                         else if (strlen(optarg) == 1)
 395                                 options.escape_char = (u_char) optarg[0];
 396                         else if (strcmp(optarg, "none") == 0)
 397                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 398                         else {
 399                                 fprintf(stderr, "Bad escape character '%s'.\n",
 400                                     optarg);
 401                                 exit(255);
 402                         }
 403                         break;
 404                 case 'c':
 405                         if (ciphers_valid(optarg)) {
 406                                 /* SSH2 only */
 407                                 options.ciphers = xstrdup(optarg);
 408                                 options.cipher = SSH_CIPHER_INVALID;
 409                         } else {
 410                                 /* SSH1 only */
 411                                 options.cipher = cipher_number(optarg);
 412                                 if (options.cipher == -1) {
 413                                         fprintf(stderr,
 414                                             "Unknown cipher type '%s'\n",
 415                                             optarg);
 416                                         exit(255);
 417                                 }
 418                                 if (options.cipher == SSH_CIPHER_3DES)
 419                                         options.ciphers = "3des-cbc";
 420                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 421                                         options.ciphers = "blowfish-cbc";
 422                                 else
 423                                         options.ciphers = (char *)-1;
 424                         }
 425                         break;
 426                 case 'm':
 427                         if (mac_valid(optarg))
 428                                 options.macs = xstrdup(optarg);
 429                         else {
 430                                 fprintf(stderr, "Unknown mac type '%s'\n",
 431                                     optarg);
 432                                 exit(255);
 433                         }
 434                         break;
 435                 case 'M':
 436                         if (options.control_master == SSHCTL_MASTER_YES)
 437                                 options.control_master = SSHCTL_MASTER_ASK;
 438                         else
 439                                 options.control_master = SSHCTL_MASTER_YES;
 440                         break;
 441                 case 'p':
 442                         options.port = a2port(optarg);
 443                         if (options.port == 0) {
 444                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 445                                 exit(255);
 446                         }
 447                         break;
 448                 case 'l':
 449                         options.user = optarg;
 450                         break;
 451
 452                 case 'L':
 453                         if (parse_forward(&fwd, optarg))
 454                                 add_local_forward(&options, &fwd);
 455                         else {
 456                                 fprintf(stderr,
 457                                     "Bad local forwarding specification '%s'\n",
 458                                     optarg);
 459                                 exit(255);
 460                         }
 461                         break;
 462
 463                 case 'R':
 464                         if (parse_forward(&fwd, optarg)) {
 465                                 add_remote_forward(&options, &fwd);
 466                         } else {
 467                                 fprintf(stderr,
 468                                     "Bad remote forwarding specification "
 469                                     "'%s'\n", optarg);
 470                                 exit(255);
 471                         }
 472                         break;
 473
 474                 case 'D':
 475                         cp = p = xstrdup(optarg);
 476                         memset(&fwd, '\0', sizeof(fwd));
 477                         fwd.connect_host = "socks";
 478                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 479                                 fprintf(stderr, "Bad dynamic forwarding "
 480                                     "specification '%.100s'\n", optarg);
 481                                 exit(255);
 482                         }
 483                         if (cp != NULL) {
 484                                 fwd.listen_port = a2port(cp);
 485                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 486                         } else {
 487                                 fwd.listen_port = a2port(fwd.listen_host);
 488                                 fwd.listen_host = NULL;
 489                         }
 490
 491                         if (fwd.listen_port == 0) {
 492                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 493                                     optarg);
 494                                 exit(255);
 495                         }
 496                         add_local_forward(&options, &fwd);
 497                         xfree(p);
 498                         break;
 499
 500                 case 'C':
 501                         options.compression = 1;
 502                         break;
 503                 case 'N':
 504                         no_shell_flag = 1;
 505                         no_tty_flag = 1;
 506                         break;
 507                 case 'T':
 508                         no_tty_flag = 1;
 509                         break;
 510                 case 'o':
 511                         dummy = 1;
 512                         line = xstrdup(optarg);
 513                         if (process_config_line(&options, host ? host : "",
 514                             line, "command-line", 0, &dummy) != 0)
 515                                 exit(255);
 516                         xfree(line);
 517                         break;
 518                 case 's':
 519                         subsystem_flag = 1;
 520                         break;
 521                 case 'S':
 522                         if (options.control_path != NULL)
 523                                 free(options.control_path);
 524                         options.control_path = xstrdup(optarg);
 525                         break;
 526                 case 'b':
 527                         options.bind_address = optarg;
 528                         break;
 529                 case 'F':
 530                         config = optarg;
 531                         break;
 532                 default:
 533                         usage();
 534                 }
 535         }
 536
 537         ac -= optind;
 538         av += optind;
 539
 540         if (ac > 0 && !host && **av != '-') {
 541                 if (strrchr(*av, '@')) {
 542                         p = xstrdup(*av);
 543                         cp = strrchr(p, '@');
 544                         if (cp == NULL || cp == p)
 545                                 usage();
 546                         options.user = p;
 547                         *cp = '\0';
 548                         host = ++cp;
 549                 } else
 550                         host = *av;
 551                 if (ac > 1) {
 552                         optind = optreset = 1;
 553                         goto again;
 554                 }
 555                 ac--, av++;
 556         }
 557
 558         /* Check that we got a host name. */
 559         if (!host)
 560                 usage();
 561
 562         SSLeay_add_all_algorithms();
 563         ERR_load_crypto_strings();
 564
 565         /* Initialize the command to execute on remote host. */
 566         buffer_init(&command);
 567
 568         /*
 569          * Save the command to execute on the remote host in a buffer. There
 570          * is no limit on the length of the command, except by the maximum
 571          * packet size.  Also sets the tty flag if there is no command.
 572          */
 573         if (!ac) {
 574                 /* No command specified - execute shell on a tty. */
 575                 tty_flag = 1;
 576                 if (subsystem_flag) {
 577                         fprintf(stderr,
 578                             "You must specify a subsystem to invoke.\n");
 579                         usage();
 580                 }
 581         } else {
 582                 /* A command has been specified.  Store it into the buffer. */
 583                 for (i = 0; i < ac; i++) {
 584                         if (i)
 585                                 buffer_append(&command, " ", 1);
 586                         buffer_append(&command, av[i], strlen(av[i]));
 587                 }
 588         }
 589
 590         /* Cannot fork to background if no command. */
 591         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 592                 fatal("Cannot fork into background without a command to execute.");
 593
 594         /* Allocate a tty by default if no command specified. */
 595         if (buffer_len(&command) == 0)
 596                 tty_flag = 1;
 597
 598         /* Force no tty */
 599         if (no_tty_flag)
 600                 tty_flag = 0;
 601         /* Do not allocate a tty if stdin is not a tty. */
 602         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 603                 if (tty_flag)
 604                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 605                 tty_flag = 0;
 606         }
 607
 608         /*
 609          * Initialize "log" output.  Since we are the client all output
 610          * actually goes to stderr.
 611          */
 612         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 613             SYSLOG_FACILITY_USER, 1);
 614
 615         /*
 616          * Read per-user configuration file.  Ignore the system wide config
 617          * file if the user specifies a config file on the command line.
 618          */
 619         if (config != NULL) {
 620                 if (!read_config_file(config, host, &options, 0))
 621                         fatal("Can't open user config file %.100s: "
 622                             "%.100s", config, strerror(errno));
 623         } else {
 624                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 625                     _PATH_SSH_USER_CONFFILE);
 626                 (void)read_config_file(buf, host, &options, 1);
 627
 628                 /* Read systemwide configuration file after use config. */
 629                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 630                     &options, 0);
 631         }
 632
 633         /* Fill configuration defaults. */
 634         fill_default_options(&options);
 635
 636         channel_set_af(options.address_family);
 637
 638         /* reinit */
 639         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 640
 641         seed_rng();
 642
 643         if (options.user == NULL)
 644                 options.user = xstrdup(pw->pw_name);
 645
 646         if (options.hostname != NULL)
 647                 host = options.hostname;
 648
 649         /* force lowercase for hostkey matching */
 650         if (options.host_key_alias != NULL) {
 651                 for (p = options.host_key_alias; *p; p++)
 652                         if (isupper(*p))
 653                                 *p = (char)tolower(*p);
 654         }
 655
 656         /* Get default port if port has not been set. */
 657         if (options.port == 0) {
 658                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 659                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 660         }
 661
 662         if (options.proxy_command != NULL &&
 663             strcmp(options.proxy_command, "none") == 0) {
 664                 xfree(options.proxy_command);
 665                 options.proxy_command = NULL;
 666         }
 667         if (options.control_path != NULL &&
 668             strcmp(options.control_path, "none") == 0) {
 669                 xfree(options.control_path);
 670                 options.control_path = NULL;
 671         }
 672
 673         if (options.control_path != NULL) {
 674                 char thishost[NI_MAXHOST];
 675
 676                 if (gethostname(thishost, sizeof(thishost)) == -1)
 677                         fatal("gethostname: %s", strerror(errno));
 678                 snprintf(buf, sizeof(buf), "%d", options.port);
 679                 cp = tilde_expand_filename(options.control_path,
 680                     original_real_uid);
 681                 xfree(options.control_path);
 682                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 683                     "r", options.user, "l", thishost, (char *)NULL);
 684                 xfree(cp);
 685         }
 686         if (mux_command != 0 && options.control_path == NULL)
 687                 fatal("No ControlPath specified for \"-O\" command");
 688         if (options.control_path != NULL)
 689                 control_client(options.control_path);
 690
 691         timeout_ms = options.connection_timeout * 1000;
 692
 693         /* Open a connection to the remote host. */
 694         if (ssh_connect(host, &hostaddr, options.port,
 695             options.address_family, options.connection_attempts, &timeout_ms,
 696             options.tcp_keep_alive,
 697 #ifdef HAVE_CYGWIN
 698             options.use_privileged_port,
 699 #else
 700             original_effective_uid == 0 && options.use_privileged_port,
 701 #endif
 702             options.proxy_command) != 0)
 703                 exit(255);
 704
 705         if (timeout_ms > 0)
 706                 debug3("timeout: %d ms remain after connect", timeout_ms);
 707
 708         /*
 709          * If we successfully made the connection, load the host private key
 710          * in case we will need it later for combined rsa-rhosts
 711          * authentication. This must be done before releasing extra
 712          * privileges, because the file is only readable by root.
 713          * If we cannot access the private keys, load the public keys
 714          * instead and try to execute the ssh-keysign helper instead.
 715          */
 716         sensitive_data.nkeys = 0;
 717         sensitive_data.keys = NULL;
 718         sensitive_data.external_keysign = 0;
 719         if (options.rhosts_rsa_authentication ||
 720             options.hostbased_authentication) {
 721                 sensitive_data.nkeys = 3;
 722                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 723                     sizeof(Key));
 724
 725                 PRIV_START;
 726                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 727                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 728                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 729                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 730                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 731                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 732                 PRIV_END;
 733
 734                 if (options.hostbased_authentication == 1 &&
 735                     sensitive_data.keys[0] == NULL &&
 736                     sensitive_data.keys[1] == NULL &&
 737                     sensitive_data.keys[2] == NULL) {
 738                         sensitive_data.keys[1] = key_load_public(
 739                             _PATH_HOST_DSA_KEY_FILE, NULL);
 740                         sensitive_data.keys[2] = key_load_public(
 741                             _PATH_HOST_RSA_KEY_FILE, NULL);
 742                         sensitive_data.external_keysign = 1;
 743                 }
 744         }
 745         /*
 746          * Get rid of any extra privileges that we may have.  We will no
 747          * longer need them.  Also, extra privileges could make it very hard
 748          * to read identity files and other non-world-readable files from the
 749          * user's home directory if it happens to be on a NFS volume where
 750          * root is mapped to nobody.
 751          */
 752         if (original_effective_uid == 0) {
 753                 PRIV_START;
 754                 permanently_set_uid(pw);
 755         }
 756
 757         /*
 758          * Now that we are back to our own permissions, create ~/.ssh
 759          * directory if it doesn't already exist.
 760          */
 761         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 762         if (stat(buf, &st) < 0)
 763                 if (mkdir(buf, 0700) < 0)
 764                         error("Could not create directory '%.200s'.", buf);
 765
 766         /* load options.identity_files */
 767         load_public_identity_files();
 768
 769         /* Expand ~ in known host file names. */
 770         /* XXX mem-leaks: */
 771         options.system_hostfile =
 772             tilde_expand_filename(options.system_hostfile, original_real_uid);
 773         options.user_hostfile =
 774             tilde_expand_filename(options.user_hostfile, original_real_uid);
 775         options.system_hostfile2 =
 776             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 777         options.user_hostfile2 =
 778             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 779
 780         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 781
 782         /* Log into the remote system.  This never returns if the login fails. */
 783         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 784             pw, timeout_ms);
 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         /* Initiate tunnel forwarding. */
 876         if (options.tun_open != SSH_TUNMODE_NO) {
 877                 if (client_request_tun_fwd(options.tun_open,
 878                     options.tun_local, options.tun_remote) == -1) {
 879                         if (options.exit_on_forward_failure)
 880                                 fatal("Could not request tunnel forwarding.");
 881                         else
 882                                 error("Could not request tunnel forwarding.");
 883                 }
 884         }
 885 }
 886
 887 static void
 888 check_agent_present(void)
 889 {
 890         if (options.forward_agent) {
 891                 /* Clear agent forwarding if we don't have an agent. */
 892                 if (!ssh_agent_present())
 893                         options.forward_agent = 0;
 894         }
 895 }
 896
 897 static int
 898 ssh_session(void)
 899 {
 900         int type;
 901         int interactive = 0;
 902         int have_tty = 0;
 903         struct winsize ws;
 904         char *cp;
 905         const char *display;
 906
 907         /* Enable compression if requested. */
 908         if (options.compression) {
 909                 debug("Requesting compression at level %d.", options.compression_level);
 910
 911                 if (options.compression_level < 1 || options.compression_level > 9)
 912                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 913
 914                 /* Send the request. */
 915                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 916                 packet_put_int(options.compression_level);
 917                 packet_send();
 918                 packet_write_wait();
 919                 type = packet_read();
 920                 if (type == SSH_SMSG_SUCCESS)
 921                         packet_start_compression(options.compression_level);
 922                 else if (type == SSH_SMSG_FAILURE)
 923                         logit("Warning: Remote host refused compression.");
 924                 else
 925                         packet_disconnect("Protocol error waiting for compression response.");
 926         }
 927         /* Allocate a pseudo tty if appropriate. */
 928         if (tty_flag) {
 929                 debug("Requesting pty.");
 930
 931                 /* Start the packet. */
 932                 packet_start(SSH_CMSG_REQUEST_PTY);
 933
 934                 /* Store TERM in the packet.  There is no limit on the
 935                    length of the string. */
 936                 cp = getenv("TERM");
 937                 if (!cp)
 938                         cp = "";
 939                 packet_put_cstring(cp);
 940
 941                 /* Store window size in the packet. */
 942                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 943                         memset(&ws, 0, sizeof(ws));
 944                 packet_put_int((u_int)ws.ws_row);
 945                 packet_put_int((u_int)ws.ws_col);
 946                 packet_put_int((u_int)ws.ws_xpixel);
 947                 packet_put_int((u_int)ws.ws_ypixel);
 948
 949                 /* Store tty modes in the packet. */
 950                 tty_make_modes(fileno(stdin), NULL);
 951
 952                 /* Send the packet, and wait for it to leave. */
 953                 packet_send();
 954                 packet_write_wait();
 955
 956                 /* Read response from the server. */
 957                 type = packet_read();
 958                 if (type == SSH_SMSG_SUCCESS) {
 959                         interactive = 1;
 960                         have_tty = 1;
 961                 } else if (type == SSH_SMSG_FAILURE)
 962                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 963                 else
 964                         packet_disconnect("Protocol error waiting for pty request response.");
 965         }
 966         /* Request X11 forwarding if enabled and DISPLAY is set. */
 967         display = getenv("DISPLAY");
 968         if (options.forward_x11 && display != NULL) {
 969                 char *proto, *data;
 970                 /* Get reasonable local authentication information. */
 971                 client_x11_get_proto(display, options.xauth_location,
 972                     options.forward_x11_trusted, &proto, &data);
 973                 /* Request forwarding with authentication spoofing. */
 974                 debug("Requesting X11 forwarding with authentication spoofing.");
 975                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 976
 977                 /* Read response from the server. */
 978                 type = packet_read();
 979                 if (type == SSH_SMSG_SUCCESS) {
 980                         interactive = 1;
 981                 } else if (type == SSH_SMSG_FAILURE) {
 982                         logit("Warning: Remote host denied X11 forwarding.");
 983                 } else {
 984                         packet_disconnect("Protocol error waiting for X11 forwarding");
 985                 }
 986         }
 987         /* Tell the packet module whether this is an interactive session. */
 988         packet_set_interactive(interactive);
 989
 990         /* Request authentication agent forwarding if appropriate. */
 991         check_agent_present();
 992
 993         if (options.forward_agent) {
 994                 debug("Requesting authentication agent forwarding.");
 995                 auth_request_forwarding();
 996
 997                 /* Read response from the server. */
 998                 type = packet_read();
 999                 packet_check_eom();
1000                 if (type != SSH_SMSG_SUCCESS)
1001                         logit("Warning: Remote host denied authentication agent forwarding.");
1002         }
1003
1004         /* Initiate port forwardings. */
1005         ssh_init_forwarding();
1006
1007         /* Execute a local command */
1008         if (options.local_command != NULL &&
1009             options.permit_local_command)
1010                 ssh_local_cmd(options.local_command);
1011
1012         /* If requested, let ssh continue in the background. */
1013         if (fork_after_authentication_flag)
1014                 if (daemon(1, 1) < 0)
1015                         fatal("daemon() failed: %.200s", strerror(errno));
1016
1017         /*
1018          * If a command was specified on the command line, execute the
1019          * command now. Otherwise request the server to start a shell.
1020          */
1021         if (buffer_len(&command) > 0) {
1022                 int len = buffer_len(&command);
1023                 if (len > 900)
1024                         len = 900;
1025                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1026                 packet_start(SSH_CMSG_EXEC_CMD);
1027                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1028                 packet_send();
1029                 packet_write_wait();
1030         } else {
1031                 debug("Requesting shell.");
1032                 packet_start(SSH_CMSG_EXEC_SHELL);
1033                 packet_send();
1034                 packet_write_wait();
1035         }
1036
1037         /* Enter the interactive session. */
1038         return client_loop(have_tty, tty_flag ?
1039             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1040 }
1041
1042 static void
1043 ssh_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1044 {
1045         int id, len;
1046
1047         id = packet_get_int();
1048         len = buffer_len(&command);
1049         if (len > 900)
1050                 len = 900;
1051         packet_check_eom();
1052         if (type == SSH2_MSG_CHANNEL_FAILURE)
1053                 fatal("Request for subsystem '%.*s' failed on channel %d",
1054                     len, (u_char *)buffer_ptr(&command), id);
1055 }
1056
1057 void
1058 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1059 {
1060         int i;
1061
1062         i = client_global_request_id++;
1063         if (i >= options.num_remote_forwards)
1064                 return;
1065         debug("remote forward %s for: listen %d, connect %s:%d",
1066             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1067             options.remote_forwards[i].listen_port,
1068             options.remote_forwards[i].connect_host,
1069             options.remote_forwards[i].connect_port);
1070         if (type == SSH2_MSG_REQUEST_FAILURE) {
1071                 if (options.exit_on_forward_failure)
1072                         fatal("Error: remote port forwarding failed for "
1073                             "listen port %d",
1074                             options.remote_forwards[i].listen_port);
1075                 else
1076                         logit("Warning: remote port forwarding failed for "
1077                             "listen port %d",
1078                             options.remote_forwards[i].listen_port);
1079         }
1080 }
1081
1082 static void
1083 ssh_control_listener(void)
1084 {
1085         struct sockaddr_un addr;
1086         mode_t old_umask;
1087         int addr_len;
1088
1089         if (options.control_path == NULL ||
1090             options.control_master == SSHCTL_MASTER_NO)
1091                 return;
1092
1093         debug("setting up multiplex master socket");
1094
1095         memset(&addr, '\0', sizeof(addr));
1096         addr.sun_family = AF_UNIX;
1097         addr_len = offsetof(struct sockaddr_un, sun_path) +
1098             strlen(options.control_path) + 1;
1099
1100         if (strlcpy(addr.sun_path, options.control_path,
1101             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1102                 fatal("ControlPath too long");
1103
1104         if ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1105                 fatal("%s socket(): %s", __func__, strerror(errno));
1106
1107         old_umask = umask(0177);
1108         if (bind(control_fd, (struct sockaddr *)&addr, addr_len) == -1) {
1109                 control_fd = -1;
1110                 if (errno == EINVAL || errno == EADDRINUSE)
1111                         fatal("ControlSocket %s already exists",
1112                             options.control_path);
1113                 else
1114                         fatal("%s bind(): %s", __func__, strerror(errno));
1115         }
1116         umask(old_umask);
1117
1118         if (listen(control_fd, 64) == -1)
1119                 fatal("%s listen(): %s", __func__, strerror(errno));
1120
1121         set_nonblock(control_fd);
1122 }
1123
1124 /* request pty/x11/agent/tcpfwd/shell for channel */
1125 static void
1126 ssh_session2_setup(int id, void *arg)
1127 {
1128         extern char **environ;
1129         const char *display;
1130         int interactive = tty_flag;
1131
1132         display = getenv("DISPLAY");
1133         if (options.forward_x11 && display != NULL) {
1134                 char *proto, *data;
1135                 /* Get reasonable local authentication information. */
1136                 client_x11_get_proto(display, options.xauth_location,
1137                     options.forward_x11_trusted, &proto, &data);
1138                 /* Request forwarding with authentication spoofing. */
1139                 debug("Requesting X11 forwarding with authentication spoofing.");
1140                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1141                 interactive = 1;
1142                 /* XXX wait for reply */
1143         }
1144
1145         check_agent_present();
1146         if (options.forward_agent) {
1147                 debug("Requesting authentication agent forwarding.");
1148                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1149                 packet_send();
1150         }
1151
1152         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1153             NULL, fileno(stdin), &command, environ, &ssh_subsystem_reply);
1154
1155         packet_set_interactive(interactive);
1156 }
1157
1158 /* open new channel for a session */
1159 static int
1160 ssh_session2_open(void)
1161 {
1162         Channel *c;
1163         int window, packetmax, in, out, err;
1164
1165         if (stdin_null_flag) {
1166                 in = open(_PATH_DEVNULL, O_RDONLY);
1167         } else {
1168                 in = dup(STDIN_FILENO);
1169         }
1170         out = dup(STDOUT_FILENO);
1171         err = dup(STDERR_FILENO);
1172
1173         if (in < 0 || out < 0 || err < 0)
1174                 fatal("dup() in/out/err failed");
1175
1176         /* enable nonblocking unless tty */
1177         if (!isatty(in))
1178                 set_nonblock(in);
1179         if (!isatty(out))
1180                 set_nonblock(out);
1181         if (!isatty(err))
1182                 set_nonblock(err);
1183
1184         window = CHAN_SES_WINDOW_DEFAULT;
1185         packetmax = CHAN_SES_PACKET_DEFAULT;
1186         if (tty_flag) {
1187                 window >>= 1;
1188                 packetmax >>= 1;
1189         }
1190         c = channel_new(
1191             "session", SSH_CHANNEL_OPENING, in, out, err,
1192             window, packetmax, CHAN_EXTENDED_WRITE,
1193             "client-session", /*nonblock*/0);
1194
1195         debug3("ssh_session2_open: channel_new: %d", c->self);
1196
1197         channel_send_open(c->self);
1198         if (!no_shell_flag)
1199                 channel_register_open_confirm(c->self,
1200                     ssh_session2_setup, NULL);
1201
1202         return c->self;
1203 }
1204
1205 static int
1206 ssh_session2(void)
1207 {
1208         int id = -1;
1209
1210         /* XXX should be pre-session */
1211         ssh_init_forwarding();
1212
1213         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1214                 id = ssh_session2_open();
1215
1216         /* Execute a local command */
1217         if (options.local_command != NULL &&
1218             options.permit_local_command)
1219                 ssh_local_cmd(options.local_command);
1220
1221         /* Start listening for multiplex clients */
1222         ssh_control_listener();
1223
1224         /* If requested, let ssh continue in the background. */
1225         if (fork_after_authentication_flag)
1226                 if (daemon(1, 1) < 0)
1227                         fatal("daemon() failed: %.200s", strerror(errno));
1228
1229         return client_loop(tty_flag, tty_flag ?
1230             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1231 }
1232
1233 static void
1234 load_public_identity_files(void)
1235 {
1236         char *filename, *cp, thishost[NI_MAXHOST];
1237         char *pwdir = NULL, *pwname = NULL;
1238         int i = 0;
1239         Key *public;
1240         struct passwd *pw;
1241 #ifdef SMARTCARD
1242         Key **keys;
1243
1244         if (options.smartcard_device != NULL &&
1245             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1246             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL) {
1247                 int count = 0;
1248                 for (i = 0; keys[i] != NULL; i++) {
1249                         count++;
1250                         memmove(&options.identity_files[1], &options.identity_files[0],
1251                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1252                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1253                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1254                         options.num_identity_files++;
1255                         options.identity_keys[0] = keys[i];
1256                         options.identity_files[0] = sc_get_key_label(keys[i]);
1257                 }
1258                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1259                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1260                 i = count;
1261                 xfree(keys);
1262         }
1263 #endif /* SMARTCARD */
1264         if ((pw = getpwuid(original_real_uid)) == NULL)
1265                 fatal("load_public_identity_files: getpwuid failed");
1266         pwname = xstrdup(pw->pw_name);
1267         pwdir = xstrdup(pw->pw_dir);
1268         if (gethostname(thishost, sizeof(thishost)) == -1)
1269                 fatal("load_public_identity_files: gethostname: %s",
1270                     strerror(errno));
1271         for (; i < options.num_identity_files; i++) {
1272                 cp = tilde_expand_filename(options.identity_files[i],
1273                     original_real_uid);
1274                 filename = percent_expand(cp, "d", pwdir,
1275                     "u", pwname, "l", thishost, "h", host,
1276                     "r", options.user, (char *)NULL);
1277                 xfree(cp);
1278                 public = key_load_public(filename, NULL);
1279                 debug("identity file %s type %d", filename,
1280                     public ? public->type : -1);
1281                 xfree(options.identity_files[i]);
1282                 options.identity_files[i] = filename;
1283                 options.identity_keys[i] = public;
1284         }
1285         bzero(pwname, strlen(pwname));
1286         xfree(pwname);
1287         bzero(pwdir, strlen(pwdir));
1288         xfree(pwdir);
1289 }
1290
1291 static void
1292 control_client_sighandler(int signo)
1293 {
1294         control_client_terminate = signo;
1295 }
1296
1297 static void
1298 control_client_sigrelay(int signo)
1299 {
1300         int save_errno = errno;
1301
1302         if (control_server_pid > 1)
1303                 kill(control_server_pid, signo);
1304
1305         errno = save_errno;
1306 }
1307
1308 static int
1309 env_permitted(char *env)
1310 {
1311         int i, ret;
1312         char name[1024], *cp;
1313
1314         if ((cp = strchr(env, '=')) == NULL || cp == env)
1315                 return (0);
1316         ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
1317         if (ret <= 0 || (size_t)ret >= sizeof(name))
1318                 fatal("env_permitted: name '%.100s...' too long", env);
1319
1320         for (i = 0; i < options.num_send_env; i++)
1321                 if (match_pattern(name, options.send_env[i]))
1322                         return (1);
1323
1324         return (0);
1325 }
1326
1327 static void
1328 control_client(const char *path)
1329 {
1330         struct sockaddr_un addr;
1331         int i, r, fd, sock, exitval[2], num_env, addr_len;
1332         Buffer m;
1333         char *term;
1334         extern char **environ;
1335         u_int  flags;
1336
1337         if (mux_command == 0)
1338                 mux_command = SSHMUX_COMMAND_OPEN;
1339
1340         switch (options.control_master) {
1341         case SSHCTL_MASTER_AUTO:
1342         case SSHCTL_MASTER_AUTO_ASK:
1343                 debug("auto-mux: Trying existing master");
1344                 /* FALLTHROUGH */
1345         case SSHCTL_MASTER_NO:
1346                 break;
1347         default:
1348                 return;
1349         }
1350
1351         memset(&addr, '\0', sizeof(addr));
1352         addr.sun_family = AF_UNIX;
1353         addr_len = offsetof(struct sockaddr_un, sun_path) +
1354             strlen(path) + 1;
1355
1356         if (strlcpy(addr.sun_path, path,
1357             sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
1358                 fatal("ControlPath too long");
1359
1360         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
1361                 fatal("%s socket(): %s", __func__, strerror(errno));
1362
1363         if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) {
1364                 if (mux_command != SSHMUX_COMMAND_OPEN) {
1365                         fatal("Control socket connect(%.100s): %s", path,
1366                             strerror(errno));
1367                 }
1368                 if (errno == ENOENT)
1369                         debug("Control socket \"%.100s\" does not exist", path);
1370                 else {
1371                         error("Control socket connect(%.100s): %s", path,
1372                             strerror(errno));
1373                 }
1374                 close(sock);
1375                 return;
1376         }
1377
1378         if (stdin_null_flag) {
1379                 if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1380                         fatal("open(/dev/null): %s", strerror(errno));
1381                 if (dup2(fd, STDIN_FILENO) == -1)
1382                         fatal("dup2: %s", strerror(errno));
1383                 if (fd > STDERR_FILENO)
1384                         close(fd);
1385         }
1386
1387         term = getenv("TERM");
1388
1389         flags = 0;
1390         if (tty_flag)
1391                 flags |= SSHMUX_FLAG_TTY;
1392         if (subsystem_flag)
1393                 flags |= SSHMUX_FLAG_SUBSYS;
1394         if (options.forward_x11)
1395                 flags |= SSHMUX_FLAG_X11_FWD;
1396         if (options.forward_agent)
1397                 flags |= SSHMUX_FLAG_AGENT_FWD;
1398
1399         signal(SIGPIPE, SIG_IGN);
1400
1401         buffer_init(&m);
1402
1403         /* Send our command to server */
1404         buffer_put_int(&m, mux_command);
1405         buffer_put_int(&m, flags);
1406         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1407                 fatal("%s: msg_send", __func__);
1408         buffer_clear(&m);
1409
1410         /* Get authorisation status and PID of controlee */
1411         if (ssh_msg_recv(sock, &m) == -1)
1412                 fatal("%s: msg_recv", __func__);
1413         if (buffer_get_char(&m) != SSHMUX_VER)
1414                 fatal("%s: wrong version", __func__);
1415         if (buffer_get_int(&m) != 1)
1416                 fatal("Connection to master denied");
1417         control_server_pid = buffer_get_int(&m);
1418
1419         buffer_clear(&m);
1420
1421         switch (mux_command) {
1422         case SSHMUX_COMMAND_ALIVE_CHECK:
1423                 fprintf(stderr, "Master running (pid=%d)\r\n",
1424                     control_server_pid);
1425                 exit(0);
1426         case SSHMUX_COMMAND_TERMINATE:
1427                 fprintf(stderr, "Exit request sent.\r\n");
1428                 exit(0);
1429         case SSHMUX_COMMAND_OPEN:
1430                 /* continue below */
1431                 break;
1432         default:
1433                 fatal("silly mux_command %d", mux_command);
1434         }
1435
1436         /* SSHMUX_COMMAND_OPEN */
1437         buffer_put_cstring(&m, term ? term : "");
1438         buffer_append(&command, "\0", 1);
1439         buffer_put_cstring(&m, buffer_ptr(&command));
1440
1441         if (options.num_send_env == 0 || environ == NULL) {
1442                 buffer_put_int(&m, 0);
1443         } else {
1444                 /* Pass environment */
1445                 num_env = 0;
1446                 for (i = 0; environ[i] != NULL; i++)
1447                         if (env_permitted(environ[i]))
1448                                 num_env++; /* Count */
1449
1450                 buffer_put_int(&m, num_env);
1451
1452                 for (i = 0; environ[i] != NULL && num_env >= 0; i++)
1453                         if (env_permitted(environ[i])) {
1454                                 num_env--;
1455                                 buffer_put_cstring(&m, environ[i]);
1456                         }
1457         }
1458
1459         if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
1460                 fatal("%s: msg_send", __func__);
1461
1462         if (mm_send_fd(sock, STDIN_FILENO) == -1 ||
1463             mm_send_fd(sock, STDOUT_FILENO) == -1 ||
1464             mm_send_fd(sock, STDERR_FILENO) == -1)
1465                 fatal("%s: send fds failed", __func__);
1466
1467         /* Wait for reply, so master has a chance to gather ttymodes */
1468         buffer_clear(&m);
1469         if (ssh_msg_recv(sock, &m) == -1)
1470                 fatal("%s: msg_recv", __func__);
1471         if (buffer_get_char(&m) != SSHMUX_VER)
1472                 fatal("%s: wrong version", __func__);
1473         buffer_free(&m);
1474
1475         signal(SIGHUP, control_client_sighandler);
1476         signal(SIGINT, control_client_sighandler);
1477         signal(SIGTERM, control_client_sighandler);
1478         signal(SIGWINCH, control_client_sigrelay);
1479
1480         if (tty_flag)
1481                 enter_raw_mode();
1482
1483         /*
1484          * Stick around until the controlee closes the client_fd.
1485          * Before it does, it is expected to write this process' exit
1486          * value (one int). This process must read the value and wait for
1487          * the closure of the client_fd; if this one closes early, the
1488          * multiplex master will terminate early too (possibly losing data).
1489          */
1490         exitval[0] = 0;
1491         for (i = 0; !control_client_terminate && i < (int)sizeof(exitval);) {
1492                 r = read(sock, (char *)exitval + i, sizeof(exitval) - i);
1493                 if (r == 0) {
1494                         debug2("Received EOF from master");
1495                         break;
1496                 }
1497                 if (r == -1) {
1498                         if (errno == EINTR)
1499                                 continue;
1500                         fatal("%s: read %s", __func__, strerror(errno));
1501                 }
1502                 i += r;
1503         }
1504
1505         close(sock);
1506         leave_raw_mode();
1507         if (i > (int)sizeof(int))
1508                 fatal("%s: master returned too much data (%d > %lu)",
1509                     __func__, i, sizeof(int));
1510         if (control_client_terminate) {
1511                 debug2("Exiting on signal %d", control_client_terminate);
1512                 exitval[0] = 255;
1513         } else if (i < (int)sizeof(int)) {
1514                 debug2("Control master terminated unexpectedly");
1515                 exitval[0] = 255;
1516         } else
1517                 debug2("Received exit status from master %d", exitval[0]);
1518
1519         if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
1520                 fprintf(stderr, "Shared connection to %s closed.\r\n", host);
1521
1522         exit(exitval[0]);
1523 }