ssh.c

   1 /* $OpenBSD: ssh.c,v 1.325 2009/03/17 21:37:00 markus 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
  53 #include <ctype.h>
  54 #include <errno.h>
  55 #include <fcntl.h>
  56 #include <netdb.h>
  57 #ifdef HAVE_PATHS_H
  58 #include <paths.h>
  59 #endif
  60 #include <pwd.h>
  61 #include <signal.h>
  62 #include <stdarg.h>
  63 #include <stddef.h>
  64 #include <stdio.h>
  65 #include <stdlib.h>
  66 #include <string.h>
  67 #include <unistd.h>
  68
  69 #include <netinet/in.h>
  70 #include <arpa/inet.h>
  71
  72 #include <openssl/evp.h>
  73 #include <openssl/err.h>
  74 #include "openbsd-compat/openssl-compat.h"
  75 #include "openbsd-compat/sys-queue.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 "uidswap.h"
 102 #include "version.h"
 103
 104 #ifdef SMARTCARD
 105 #include "scard.h"
 106 #endif
 107
 108 extern char *__progname;
 109
 110 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 111 int debug_flag = 0;
 112
 113 /* Flag indicating whether a tty should be allocated */
 114 int tty_flag = 0;
 115 int no_tty_flag = 0;
 116 int force_tty_flag = 0;
 117
 118 /* don't exec a shell */
 119 int no_shell_flag = 0;
 120
 121 /*
 122  * Flag indicating that nothing should be read from stdin.  This can be set
 123  * on the command line.
 124  */
 125 int stdin_null_flag = 0;
 126
 127 /*
 128  * Flag indicating that ssh should fork after authentication.  This is useful
 129  * so that the passphrase can be entered manually, and then ssh goes to the
 130  * background.
 131  */
 132 int fork_after_authentication_flag = 0;
 133
 134 /*
 135  * General data structure for command line options and options configurable
 136  * in configuration files.  See readconf.h.
 137  */
 138 Options options;
 139
 140 /* optional user configfile */
 141 char *config = NULL;
 142
 143 /*
 144  * Name of the host we are connecting to.  This is the name given on the
 145  * command line, or the HostName specified for the user-supplied name in a
 146  * configuration file.
 147  */
 148 char *host;
 149
 150 /* socket address the host resolves to */
 151 struct sockaddr_storage hostaddr;
 152
 153 /* Private host keys. */
 154 Sensitive sensitive_data;
 155
 156 /* Original real UID. */
 157 uid_t original_real_uid;
 158 uid_t original_effective_uid;
 159
 160 /* command to be executed */
 161 Buffer command;
 162
 163 /* Should we execute a command or invoke a subsystem? */
 164 int subsystem_flag = 0;
 165
 166 /* # of replies received for global requests */
 167 static int remote_forward_confirms_received = 0;
 168
 169 /* pid of proxycommand child process */
 170 pid_t proxy_command_pid = 0;
 171
 172 /* mux.c */
 173 extern int muxserver_sock;
 174 extern u_int muxclient_command;
 175
 176 /* Prints a help message to the user.  This function never returns. */
 177
 178 static void
 179 usage(void)
 180 {
 181         fprintf(stderr,
 182 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
 183 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 184 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 185 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 186 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 187 "           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
 188         );
 189         exit(255);
 190 }
 191
 192 static int ssh_session(void);
 193 static int ssh_session2(void);
 194 static void load_public_identity_files(void);
 195
 196 /* from muxclient.c */
 197 void muxclient(const char *);
 198 void muxserver_listen(void);
 199
 200 /*
 201  * Main program for the ssh client.
 202  */
 203 int
 204 main(int ac, char **av)
 205 {
 206         int i, opt, exit_status, use_syslog;
 207         char *p, *cp, *line, *argv0, buf[256];
 208         struct stat st;
 209         struct passwd *pw;
 210         int dummy, timeout_ms;
 211         extern int optind, optreset;
 212         extern char *optarg;
 213         struct servent *sp;
 214         Forward fwd;
 215
 216         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 217         sanitise_stdfd();
 218
 219         __progname = ssh_get_progname(av[0]);
 220         init_rng();
 221
 222         /*
 223          * Save the original real uid.  It will be needed later (uid-swapping
 224          * may clobber the real uid).
 225          */
 226         original_real_uid = getuid();
 227         original_effective_uid = geteuid();
 228
 229         /*
 230          * Use uid-swapping to give up root privileges for the duration of
 231          * option processing.  We will re-instantiate the rights when we are
 232          * ready to create the privileged port, and will permanently drop
 233          * them when the port has been created (actually, when the connection
 234          * has been made, as we may need to create the port several times).
 235          */
 236         PRIV_END;
 237
 238 #ifdef HAVE_SETRLIMIT
 239         /* If we are installed setuid root be careful to not drop core. */
 240         if (original_real_uid != original_effective_uid) {
 241                 struct rlimit rlim;
 242                 rlim.rlim_cur = rlim.rlim_max = 0;
 243                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 244                         fatal("setrlimit failed: %.100s", strerror(errno));
 245         }
 246 #endif
 247         /* Get user data. */
 248         pw = getpwuid(original_real_uid);
 249         if (!pw) {
 250                 logit("You don't exist, go away!");
 251                 exit(255);
 252         }
 253         /* Take a copy of the returned structure. */
 254         pw = pwcopy(pw);
 255
 256         /*
 257          * Set our umask to something reasonable, as some files are created
 258          * with the default umask.  This will make them world-readable but
 259          * writable only by the owner, which is ok for all files for which we
 260          * don't set the modes explicitly.
 261          */
 262         umask(022);
 263
 264         /*
 265          * Initialize option structure to indicate that no values have been
 266          * set.
 267          */
 268         initialize_options(&options);
 269
 270         /* Parse command-line arguments. */
 271         host = NULL;
 272         use_syslog = 0;
 273         argv0 = av[0];
 274
 275  again:
 276         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 277             "ACD:F:I:KL:MNO:PR:S:TVw:XYy")) != -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                         use_syslog = 1;
 306                         break;
 307                 case 'Y':
 308                         options.forward_x11 = 1;
 309                         options.forward_x11_trusted = 1;
 310                         break;
 311                 case 'g':
 312                         options.gateway_ports = 1;
 313                         break;
 314                 case 'O':
 315                         if (strcmp(optarg, "check") == 0)
 316                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 317                         else if (strcmp(optarg, "exit") == 0)
 318                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 319                         else
 320                                 fatal("Invalid multiplex command.");
 321                         break;
 322                 case 'P':       /* deprecated */
 323                         options.use_privileged_port = 0;
 324                         break;
 325                 case 'a':
 326                         options.forward_agent = 0;
 327                         break;
 328                 case 'A':
 329                         options.forward_agent = 1;
 330                         break;
 331                 case 'k':
 332                         options.gss_deleg_creds = 0;
 333                         break;
 334                 case 'K':
 335                         options.gss_authentication = 1;
 336                         options.gss_deleg_creds = 1;
 337                         break;
 338                 case 'i':
 339                         if (stat(optarg, &st) < 0) {
 340                                 fprintf(stderr, "Warning: Identity file %s "
 341                                     "not accessible: %s.\n", optarg,
 342                                     strerror(errno));
 343                                 break;
 344                         }
 345                         if (options.num_identity_files >=
 346                             SSH_MAX_IDENTITY_FILES)
 347                                 fatal("Too many identity files specified "
 348                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 349                         options.identity_files[options.num_identity_files++] =
 350                             xstrdup(optarg);
 351                         break;
 352                 case 'I':
 353 #ifdef SMARTCARD
 354                         options.smartcard_device = xstrdup(optarg);
 355 #else
 356                         fprintf(stderr, "no support for smartcards.\n");
 357 #endif
 358                         break;
 359                 case 't':
 360                         if (tty_flag)
 361                                 force_tty_flag = 1;
 362                         tty_flag = 1;
 363                         break;
 364                 case 'v':
 365                         if (debug_flag == 0) {
 366                                 debug_flag = 1;
 367                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 368                         } else {
 369                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 370                                         options.log_level++;
 371                                 break;
 372                         }
 373                         /* FALLTHROUGH */
 374                 case 'V':
 375                         fprintf(stderr, "%s, %s\n",
 376                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 377                         if (opt == 'V')
 378                                 exit(0);
 379                         break;
 380                 case 'w':
 381                         if (options.tun_open == -1)
 382                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 383                         options.tun_local = a2tun(optarg, &options.tun_remote);
 384                         if (options.tun_local == SSH_TUNID_ERR) {
 385                                 fprintf(stderr,
 386                                     "Bad tun device '%s'\n", optarg);
 387                                 exit(255);
 388                         }
 389                         break;
 390                 case 'q':
 391                         options.log_level = SYSLOG_LEVEL_QUIET;
 392                         break;
 393                 case 'e':
 394                         if (optarg[0] == '^' && optarg[2] == 0 &&
 395                             (u_char) optarg[1] >= 64 &&
 396                             (u_char) optarg[1] < 128)
 397                                 options.escape_char = (u_char) optarg[1] & 31;
 398                         else if (strlen(optarg) == 1)
 399                                 options.escape_char = (u_char) optarg[0];
 400                         else if (strcmp(optarg, "none") == 0)
 401                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 402                         else {
 403                                 fprintf(stderr, "Bad escape character '%s'.\n",
 404                                     optarg);
 405                                 exit(255);
 406                         }
 407                         break;
 408                 case 'c':
 409                         if (ciphers_valid(optarg)) {
 410                                 /* SSH2 only */
 411                                 options.ciphers = xstrdup(optarg);
 412                                 options.cipher = SSH_CIPHER_INVALID;
 413                         } else {
 414                                 /* SSH1 only */
 415                                 options.cipher = cipher_number(optarg);
 416                                 if (options.cipher == -1) {
 417                                         fprintf(stderr,
 418                                             "Unknown cipher type '%s'\n",
 419                                             optarg);
 420                                         exit(255);
 421                                 }
 422                                 if (options.cipher == SSH_CIPHER_3DES)
 423                                         options.ciphers = "3des-cbc";
 424                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 425                                         options.ciphers = "blowfish-cbc";
 426                                 else
 427                                         options.ciphers = (char *)-1;
 428                         }
 429                         break;
 430                 case 'm':
 431                         if (mac_valid(optarg))
 432                                 options.macs = xstrdup(optarg);
 433                         else {
 434                                 fprintf(stderr, "Unknown mac type '%s'\n",
 435                                     optarg);
 436                                 exit(255);
 437                         }
 438                         break;
 439                 case 'M':
 440                         if (options.control_master == SSHCTL_MASTER_YES)
 441                                 options.control_master = SSHCTL_MASTER_ASK;
 442                         else
 443                                 options.control_master = SSHCTL_MASTER_YES;
 444                         break;
 445                 case 'p':
 446                         options.port = a2port(optarg);
 447                         if (options.port <= 0) {
 448                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 449                                 exit(255);
 450                         }
 451                         break;
 452                 case 'l':
 453                         options.user = optarg;
 454                         break;
 455
 456                 case 'L':
 457                         if (parse_forward(&fwd, optarg, 0, 0))
 458                                 add_local_forward(&options, &fwd);
 459                         else {
 460                                 fprintf(stderr,
 461                                     "Bad local forwarding specification '%s'\n",
 462                                     optarg);
 463                                 exit(255);
 464                         }
 465                         break;
 466
 467                 case 'R':
 468                         if (parse_forward(&fwd, optarg, 0, 1)) {
 469                                 add_remote_forward(&options, &fwd);
 470                         } else {
 471                                 fprintf(stderr,
 472                                     "Bad remote forwarding specification "
 473                                     "'%s'\n", optarg);
 474                                 exit(255);
 475                         }
 476                         break;
 477
 478                 case 'D':
 479                         if (parse_forward(&fwd, optarg, 1, 0)) {
 480                                 add_local_forward(&options, &fwd);
 481                         } else {
 482                                 fprintf(stderr,
 483                                     "Bad dynamic forwarding specification "
 484                                     "'%s'\n", optarg);
 485                                 exit(255);
 486                         }
 487                         break;
 488
 489                 case 'C':
 490                         options.compression = 1;
 491                         break;
 492                 case 'N':
 493                         no_shell_flag = 1;
 494                         no_tty_flag = 1;
 495                         break;
 496                 case 'T':
 497                         no_tty_flag = 1;
 498                         break;
 499                 case 'o':
 500                         dummy = 1;
 501                         line = xstrdup(optarg);
 502                         if (process_config_line(&options, host ? host : "",
 503                             line, "command-line", 0, &dummy) != 0)
 504                                 exit(255);
 505                         xfree(line);
 506                         break;
 507                 case 's':
 508                         subsystem_flag = 1;
 509                         break;
 510                 case 'S':
 511                         if (options.control_path != NULL)
 512                                 free(options.control_path);
 513                         options.control_path = xstrdup(optarg);
 514                         break;
 515                 case 'b':
 516                         options.bind_address = optarg;
 517                         break;
 518                 case 'F':
 519                         config = optarg;
 520                         break;
 521                 default:
 522                         usage();
 523                 }
 524         }
 525
 526         ac -= optind;
 527         av += optind;
 528
 529         if (ac > 0 && !host && **av != '-') {
 530                 if (strrchr(*av, '@')) {
 531                         p = xstrdup(*av);
 532                         cp = strrchr(p, '@');
 533                         if (cp == NULL || cp == p)
 534                                 usage();
 535                         options.user = p;
 536                         *cp = '\0';
 537                         host = ++cp;
 538                 } else
 539                         host = *av;
 540                 if (ac > 1) {
 541                         optind = optreset = 1;
 542                         goto again;
 543                 }
 544                 ac--, av++;
 545         }
 546
 547         /* Check that we got a host name. */
 548         if (!host)
 549                 usage();
 550
 551         SSLeay_add_all_algorithms();
 552         ERR_load_crypto_strings();
 553
 554         /* Initialize the command to execute on remote host. */
 555         buffer_init(&command);
 556
 557         /*
 558          * Save the command to execute on the remote host in a buffer. There
 559          * is no limit on the length of the command, except by the maximum
 560          * packet size.  Also sets the tty flag if there is no command.
 561          */
 562         if (!ac) {
 563                 /* No command specified - execute shell on a tty. */
 564                 tty_flag = 1;
 565                 if (subsystem_flag) {
 566                         fprintf(stderr,
 567                             "You must specify a subsystem to invoke.\n");
 568                         usage();
 569                 }
 570         } else {
 571                 /* A command has been specified.  Store it into the buffer. */
 572                 for (i = 0; i < ac; i++) {
 573                         if (i)
 574                                 buffer_append(&command, " ", 1);
 575                         buffer_append(&command, av[i], strlen(av[i]));
 576                 }
 577         }
 578
 579         /* Cannot fork to background if no command. */
 580         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 581             !no_shell_flag)
 582                 fatal("Cannot fork into background without a command "
 583                     "to execute.");
 584
 585         /* Allocate a tty by default if no command specified. */
 586         if (buffer_len(&command) == 0)
 587                 tty_flag = 1;
 588
 589         /* Force no tty */
 590         if (no_tty_flag)
 591                 tty_flag = 0;
 592         /* Do not allocate a tty if stdin is not a tty. */
 593         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 594                 if (tty_flag)
 595                         logit("Pseudo-terminal will not be allocated because "
 596                             "stdin is not a terminal.");
 597                 tty_flag = 0;
 598         }
 599
 600         /*
 601          * Initialize "log" output.  Since we are the client all output
 602          * actually goes to stderr.
 603          */
 604         log_init(argv0,
 605             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 606             SYSLOG_FACILITY_USER, !use_syslog);
 607
 608         /*
 609          * Read per-user configuration file.  Ignore the system wide config
 610          * file if the user specifies a config file on the command line.
 611          */
 612         if (config != NULL) {
 613                 if (!read_config_file(config, host, &options, 0))
 614                         fatal("Can't open user config file %.100s: "
 615                             "%.100s", config, strerror(errno));
 616         } else {
 617                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 618                     _PATH_SSH_USER_CONFFILE);
 619                 (void)read_config_file(buf, host, &options, 1);
 620
 621                 /* Read systemwide configuration file after use config. */
 622                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 623                     &options, 0);
 624         }
 625
 626         /* Fill configuration defaults. */
 627         fill_default_options(&options);
 628
 629         channel_set_af(options.address_family);
 630
 631         /* reinit */
 632         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 633
 634         seed_rng();
 635
 636         if (options.user == NULL)
 637                 options.user = xstrdup(pw->pw_name);
 638
 639         /* Get default port if port has not been set. */
 640         if (options.port == 0) {
 641                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 642                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 643         }
 644
 645         if (options.local_command != NULL) {
 646                 char thishost[NI_MAXHOST];
 647
 648                 if (gethostname(thishost, sizeof(thishost)) == -1)
 649                         fatal("gethostname: %s", strerror(errno));
 650                 snprintf(buf, sizeof(buf), "%d", options.port);
 651                 debug3("expanding LocalCommand: %s", options.local_command);
 652                 cp = options.local_command;
 653                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 654                     "h", options.hostname? options.hostname : host,
 655                     "l", thishost, "n", host, "r", options.user, "p", buf,
 656                     "u", pw->pw_name, (char *)NULL);
 657                 debug3("expanded LocalCommand: %s", options.local_command);
 658                 xfree(cp);
 659         }
 660
 661         if (options.hostname != NULL)
 662                 host = options.hostname;
 663
 664         /* force lowercase for hostkey matching */
 665         if (options.host_key_alias != NULL) {
 666                 for (p = options.host_key_alias; *p; p++)
 667                         if (isupper(*p))
 668                                 *p = (char)tolower(*p);
 669         }
 670
 671         if (options.proxy_command != NULL &&
 672             strcmp(options.proxy_command, "none") == 0) {
 673                 xfree(options.proxy_command);
 674                 options.proxy_command = NULL;
 675         }
 676         if (options.control_path != NULL &&
 677             strcmp(options.control_path, "none") == 0) {
 678                 xfree(options.control_path);
 679                 options.control_path = NULL;
 680         }
 681
 682         if (options.control_path != NULL) {
 683                 char thishost[NI_MAXHOST];
 684
 685                 if (gethostname(thishost, sizeof(thishost)) == -1)
 686                         fatal("gethostname: %s", strerror(errno));
 687                 snprintf(buf, sizeof(buf), "%d", options.port);
 688                 cp = tilde_expand_filename(options.control_path,
 689                     original_real_uid);
 690                 xfree(options.control_path);
 691                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 692                     "r", options.user, "l", thishost, (char *)NULL);
 693                 xfree(cp);
 694         }
 695         if (muxclient_command != 0 && options.control_path == NULL)
 696                 fatal("No ControlPath specified for \"-O\" command");
 697         if (options.control_path != NULL)
 698                 muxclient(options.control_path);
 699
 700         timeout_ms = options.connection_timeout * 1000;
 701
 702         /* Open a connection to the remote host. */
 703         if (ssh_connect(host, &hostaddr, options.port,
 704             options.address_family, options.connection_attempts, &timeout_ms,
 705             options.tcp_keep_alive,
 706 #ifdef HAVE_CYGWIN
 707             options.use_privileged_port,
 708 #else
 709             original_effective_uid == 0 && options.use_privileged_port,
 710 #endif
 711             options.proxy_command) != 0)
 712                 exit(255);
 713
 714         if (timeout_ms > 0)
 715                 debug3("timeout: %d ms remain after connect", timeout_ms);
 716
 717         /*
 718          * If we successfully made the connection, load the host private key
 719          * in case we will need it later for combined rsa-rhosts
 720          * authentication. This must be done before releasing extra
 721          * privileges, because the file is only readable by root.
 722          * If we cannot access the private keys, load the public keys
 723          * instead and try to execute the ssh-keysign helper instead.
 724          */
 725         sensitive_data.nkeys = 0;
 726         sensitive_data.keys = NULL;
 727         sensitive_data.external_keysign = 0;
 728         if (options.rhosts_rsa_authentication ||
 729             options.hostbased_authentication) {
 730                 sensitive_data.nkeys = 3;
 731                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 732                     sizeof(Key));
 733
 734                 PRIV_START;
 735                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 736                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 737                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 738                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 739                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 740                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 741                 PRIV_END;
 742
 743                 if (options.hostbased_authentication == 1 &&
 744                     sensitive_data.keys[0] == NULL &&
 745                     sensitive_data.keys[1] == NULL &&
 746                     sensitive_data.keys[2] == NULL) {
 747                         sensitive_data.keys[1] = key_load_public(
 748                             _PATH_HOST_DSA_KEY_FILE, NULL);
 749                         sensitive_data.keys[2] = key_load_public(
 750                             _PATH_HOST_RSA_KEY_FILE, NULL);
 751                         sensitive_data.external_keysign = 1;
 752                 }
 753         }
 754         /*
 755          * Get rid of any extra privileges that we may have.  We will no
 756          * longer need them.  Also, extra privileges could make it very hard
 757          * to read identity files and other non-world-readable files from the
 758          * user's home directory if it happens to be on a NFS volume where
 759          * root is mapped to nobody.
 760          */
 761         if (original_effective_uid == 0) {
 762                 PRIV_START;
 763                 permanently_set_uid(pw);
 764         }
 765
 766         /*
 767          * Now that we are back to our own permissions, create ~/.ssh
 768          * directory if it doesn't already exist.
 769          */
 770         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir,
 771             strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 772         if (stat(buf, &st) < 0)
 773                 if (mkdir(buf, 0700) < 0)
 774                         error("Could not create directory '%.200s'.", buf);
 775
 776         /* load options.identity_files */
 777         load_public_identity_files();
 778
 779         /* Expand ~ in known host file names. */
 780         /* XXX mem-leaks: */
 781         options.system_hostfile =
 782             tilde_expand_filename(options.system_hostfile, original_real_uid);
 783         options.user_hostfile =
 784             tilde_expand_filename(options.user_hostfile, original_real_uid);
 785         options.system_hostfile2 =
 786             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 787         options.user_hostfile2 =
 788             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 789
 790         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 791
 792         /* Log into the remote system.  Never returns if the login fails. */
 793         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 794             pw, timeout_ms);
 795
 796         /* We no longer need the private host keys.  Clear them now. */
 797         if (sensitive_data.nkeys != 0) {
 798                 for (i = 0; i < sensitive_data.nkeys; i++) {
 799                         if (sensitive_data.keys[i] != NULL) {
 800                                 /* Destroys contents safely */
 801                                 debug3("clear hostkey %d", i);
 802                                 key_free(sensitive_data.keys[i]);
 803                                 sensitive_data.keys[i] = NULL;
 804                         }
 805                 }
 806                 xfree(sensitive_data.keys);
 807         }
 808         for (i = 0; i < options.num_identity_files; i++) {
 809                 if (options.identity_files[i]) {
 810                         xfree(options.identity_files[i]);
 811                         options.identity_files[i] = NULL;
 812                 }
 813                 if (options.identity_keys[i]) {
 814                         key_free(options.identity_keys[i]);
 815                         options.identity_keys[i] = NULL;
 816                 }
 817         }
 818
 819         exit_status = compat20 ? ssh_session2() : ssh_session();
 820         packet_close();
 821
 822         if (options.control_path != NULL && muxserver_sock != -1)
 823                 unlink(options.control_path);
 824
 825         /*
 826          * Send SIGHUP to proxy command if used. We don't wait() in
 827          * case it hangs and instead rely on init to reap the child
 828          */
 829         if (proxy_command_pid > 1)
 830                 kill(proxy_command_pid, SIGHUP);
 831
 832         return exit_status;
 833 }
 834
 835 /* Callback for remote forward global requests */
 836 static void
 837 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 838 {
 839         Forward *rfwd = (Forward *)ctxt;
 840
 841         /* XXX verbose() on failure? */
 842         debug("remote forward %s for: listen %d, connect %s:%d",
 843             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
 844             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
 845         if (type == SSH2_MSG_REQUEST_SUCCESS && rfwd->listen_port == 0) {
 846                 logit("Allocated port %u for remote forward to %s:%d",
 847                         packet_get_int(),
 848                         rfwd->connect_host, rfwd->connect_port);
 849         }
 850
 851         if (type == SSH2_MSG_REQUEST_FAILURE) {
 852                 if (options.exit_on_forward_failure)
 853                         fatal("Error: remote port forwarding failed for "
 854                             "listen port %d", rfwd->listen_port);
 855                 else
 856                         logit("Warning: remote port forwarding failed for "
 857                             "listen port %d", rfwd->listen_port);
 858         }
 859         if (++remote_forward_confirms_received == options.num_remote_forwards) {
 860                 debug("All remote forwarding requests processed");
 861                 if (fork_after_authentication_flag) {
 862                         fork_after_authentication_flag = 0;
 863                         if (daemon(1, 1) < 0)
 864                                 fatal("daemon() failed: %.200s",
 865                                     strerror(errno));
 866                 }
 867         }
 868 }
 869
 870 static void
 871 ssh_init_forwarding(void)
 872 {
 873         int success = 0;
 874         int i;
 875
 876         /* Initiate local TCP/IP port forwardings. */
 877         for (i = 0; i < options.num_local_forwards; i++) {
 878                 debug("Local connections to %.200s:%d forwarded to remote "
 879                     "address %.200s:%d",
 880                     (options.local_forwards[i].listen_host == NULL) ?
 881                     (options.gateway_ports ? "*" : "LOCALHOST") :
 882                     options.local_forwards[i].listen_host,
 883                     options.local_forwards[i].listen_port,
 884                     options.local_forwards[i].connect_host,
 885                     options.local_forwards[i].connect_port);
 886                 success += channel_setup_local_fwd_listener(
 887                     options.local_forwards[i].listen_host,
 888                     options.local_forwards[i].listen_port,
 889                     options.local_forwards[i].connect_host,
 890                     options.local_forwards[i].connect_port,
 891                     options.gateway_ports);
 892         }
 893         if (i > 0 && success != i && options.exit_on_forward_failure)
 894                 fatal("Could not request local forwarding.");
 895         if (i > 0 && success == 0)
 896                 error("Could not request local forwarding.");
 897
 898         /* Initiate remote TCP/IP port forwardings. */
 899         for (i = 0; i < options.num_remote_forwards; i++) {
 900                 debug("Remote connections from %.200s:%d forwarded to "
 901                     "local address %.200s:%d",
 902                     (options.remote_forwards[i].listen_host == NULL) ?
 903                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 904                     options.remote_forwards[i].listen_port,
 905                     options.remote_forwards[i].connect_host,
 906                     options.remote_forwards[i].connect_port);
 907                 if (channel_request_remote_forwarding(
 908                     options.remote_forwards[i].listen_host,
 909                     options.remote_forwards[i].listen_port,
 910                     options.remote_forwards[i].connect_host,
 911                     options.remote_forwards[i].connect_port) < 0) {
 912                         if (options.exit_on_forward_failure)
 913                                 fatal("Could not request remote forwarding.");
 914                         else
 915                                 logit("Warning: Could not request remote "
 916                                     "forwarding.");
 917                 }
 918                 client_register_global_confirm(ssh_confirm_remote_forward,
 919                     &options.remote_forwards[i]);
 920         }
 921
 922         /* Initiate tunnel forwarding. */
 923         if (options.tun_open != SSH_TUNMODE_NO) {
 924                 if (client_request_tun_fwd(options.tun_open,
 925                     options.tun_local, options.tun_remote) == -1) {
 926                         if (options.exit_on_forward_failure)
 927                                 fatal("Could not request tunnel forwarding.");
 928                         else
 929                                 error("Could not request tunnel forwarding.");
 930                 }
 931         }
 932 }
 933
 934 static void
 935 check_agent_present(void)
 936 {
 937         if (options.forward_agent) {
 938                 /* Clear agent forwarding if we don't have an agent. */
 939                 if (!ssh_agent_present())
 940                         options.forward_agent = 0;
 941         }
 942 }
 943
 944 static int
 945 ssh_session(void)
 946 {
 947         int type;
 948         int interactive = 0;
 949         int have_tty = 0;
 950         struct winsize ws;
 951         char *cp;
 952         const char *display;
 953
 954         /* Enable compression if requested. */
 955         if (options.compression) {
 956                 debug("Requesting compression at level %d.",
 957                     options.compression_level);
 958
 959                 if (options.compression_level < 1 ||
 960                     options.compression_level > 9)
 961                         fatal("Compression level must be from 1 (fast) to "
 962                             "9 (slow, best).");
 963
 964                 /* Send the request. */
 965                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 966                 packet_put_int(options.compression_level);
 967                 packet_send();
 968                 packet_write_wait();
 969                 type = packet_read();
 970                 if (type == SSH_SMSG_SUCCESS)
 971                         packet_start_compression(options.compression_level);
 972                 else if (type == SSH_SMSG_FAILURE)
 973                         logit("Warning: Remote host refused compression.");
 974                 else
 975                         packet_disconnect("Protocol error waiting for "
 976                             "compression response.");
 977         }
 978         /* Allocate a pseudo tty if appropriate. */
 979         if (tty_flag) {
 980                 debug("Requesting pty.");
 981
 982                 /* Start the packet. */
 983                 packet_start(SSH_CMSG_REQUEST_PTY);
 984
 985                 /* Store TERM in the packet.  There is no limit on the
 986                    length of the string. */
 987                 cp = getenv("TERM");
 988                 if (!cp)
 989                         cp = "";
 990                 packet_put_cstring(cp);
 991
 992                 /* Store window size in the packet. */
 993                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 994                         memset(&ws, 0, sizeof(ws));
 995                 packet_put_int((u_int)ws.ws_row);
 996                 packet_put_int((u_int)ws.ws_col);
 997                 packet_put_int((u_int)ws.ws_xpixel);
 998                 packet_put_int((u_int)ws.ws_ypixel);
 999
1000                 /* Store tty modes in the packet. */
1001                 tty_make_modes(fileno(stdin), NULL);
1002
1003                 /* Send the packet, and wait for it to leave. */
1004                 packet_send();
1005                 packet_write_wait();
1006
1007                 /* Read response from the server. */
1008                 type = packet_read();
1009                 if (type == SSH_SMSG_SUCCESS) {
1010                         interactive = 1;
1011                         have_tty = 1;
1012                 } else if (type == SSH_SMSG_FAILURE)
1013                         logit("Warning: Remote host failed or refused to "
1014                             "allocate a pseudo tty.");
1015                 else
1016                         packet_disconnect("Protocol error waiting for pty "
1017                             "request response.");
1018         }
1019         /* Request X11 forwarding if enabled and DISPLAY is set. */
1020         display = getenv("DISPLAY");
1021         if (options.forward_x11 && display != NULL) {
1022                 char *proto, *data;
1023                 /* Get reasonable local authentication information. */
1024                 client_x11_get_proto(display, options.xauth_location,
1025                     options.forward_x11_trusted, &proto, &data);
1026                 /* Request forwarding with authentication spoofing. */
1027                 debug("Requesting X11 forwarding with authentication "
1028                     "spoofing.");
1029                 x11_request_forwarding_with_spoofing(0, display, proto, data);
1030
1031                 /* Read response from the server. */
1032                 type = packet_read();
1033                 if (type == SSH_SMSG_SUCCESS) {
1034                         interactive = 1;
1035                 } else if (type == SSH_SMSG_FAILURE) {
1036                         logit("Warning: Remote host denied X11 forwarding.");
1037                 } else {
1038                         packet_disconnect("Protocol error waiting for X11 "
1039                             "forwarding");
1040                 }
1041         }
1042         /* Tell the packet module whether this is an interactive session. */
1043         packet_set_interactive(interactive);
1044
1045         /* Request authentication agent forwarding if appropriate. */
1046         check_agent_present();
1047
1048         if (options.forward_agent) {
1049                 debug("Requesting authentication agent forwarding.");
1050                 auth_request_forwarding();
1051
1052                 /* Read response from the server. */
1053                 type = packet_read();
1054                 packet_check_eom();
1055                 if (type != SSH_SMSG_SUCCESS)
1056                         logit("Warning: Remote host denied authentication agent forwarding.");
1057         }
1058
1059         /* Initiate port forwardings. */
1060         ssh_init_forwarding();
1061
1062         /* Execute a local command */
1063         if (options.local_command != NULL &&
1064             options.permit_local_command)
1065                 ssh_local_cmd(options.local_command);
1066
1067         /*
1068          * If requested and we are not interested in replies to remote
1069          * forwarding requests, then let ssh continue in the background.
1070          */
1071         if (fork_after_authentication_flag &&
1072             (!options.exit_on_forward_failure ||
1073             options.num_remote_forwards == 0)) {
1074                 fork_after_authentication_flag = 0;
1075                 if (daemon(1, 1) < 0)
1076                         fatal("daemon() failed: %.200s", strerror(errno));
1077         }
1078
1079         /*
1080          * If a command was specified on the command line, execute the
1081          * command now. Otherwise request the server to start a shell.
1082          */
1083         if (buffer_len(&command) > 0) {
1084                 int len = buffer_len(&command);
1085                 if (len > 900)
1086                         len = 900;
1087                 debug("Sending command: %.*s", len,
1088                     (u_char *)buffer_ptr(&command));
1089                 packet_start(SSH_CMSG_EXEC_CMD);
1090                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1091                 packet_send();
1092                 packet_write_wait();
1093         } else {
1094                 debug("Requesting shell.");
1095                 packet_start(SSH_CMSG_EXEC_SHELL);
1096                 packet_send();
1097                 packet_write_wait();
1098         }
1099
1100         /* Enter the interactive session. */
1101         return client_loop(have_tty, tty_flag ?
1102             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1103 }
1104
1105 /* request pty/x11/agent/tcpfwd/shell for channel */
1106 static void
1107 ssh_session2_setup(int id, void *arg)
1108 {
1109         extern char **environ;
1110         const char *display;
1111         int interactive = tty_flag;
1112
1113         display = getenv("DISPLAY");
1114         if (options.forward_x11 && display != NULL) {
1115                 char *proto, *data;
1116                 /* Get reasonable local authentication information. */
1117                 client_x11_get_proto(display, options.xauth_location,
1118                     options.forward_x11_trusted, &proto, &data);
1119                 /* Request forwarding with authentication spoofing. */
1120                 debug("Requesting X11 forwarding with authentication "
1121                     "spoofing.");
1122                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1123                 interactive = 1;
1124                 /* XXX wait for reply */
1125         }
1126
1127         check_agent_present();
1128         if (options.forward_agent) {
1129                 debug("Requesting authentication agent forwarding.");
1130                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1131                 packet_send();
1132         }
1133
1134         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1135             NULL, fileno(stdin), &command, environ);
1136
1137         packet_set_interactive(interactive);
1138 }
1139
1140 /* open new channel for a session */
1141 static int
1142 ssh_session2_open(void)
1143 {
1144         Channel *c;
1145         int window, packetmax, in, out, err;
1146
1147         if (stdin_null_flag) {
1148                 in = open(_PATH_DEVNULL, O_RDONLY);
1149         } else {
1150                 in = dup(STDIN_FILENO);
1151         }
1152         out = dup(STDOUT_FILENO);
1153         err = dup(STDERR_FILENO);
1154
1155         if (in < 0 || out < 0 || err < 0)
1156                 fatal("dup() in/out/err failed");
1157
1158         /* enable nonblocking unless tty */
1159         if (!isatty(in))
1160                 set_nonblock(in);
1161         if (!isatty(out))
1162                 set_nonblock(out);
1163         if (!isatty(err))
1164                 set_nonblock(err);
1165
1166         window = CHAN_SES_WINDOW_DEFAULT;
1167         packetmax = CHAN_SES_PACKET_DEFAULT;
1168         if (tty_flag) {
1169                 window >>= 1;
1170                 packetmax >>= 1;
1171         }
1172         c = channel_new(
1173             "session", SSH_CHANNEL_OPENING, in, out, err,
1174             window, packetmax, CHAN_EXTENDED_WRITE,
1175             "client-session", /*nonblock*/0);
1176
1177         debug3("ssh_session2_open: channel_new: %d", c->self);
1178
1179         channel_send_open(c->self);
1180         if (!no_shell_flag)
1181                 channel_register_open_confirm(c->self,
1182                     ssh_session2_setup, NULL);
1183
1184         return c->self;
1185 }
1186
1187 static int
1188 ssh_session2(void)
1189 {
1190         int id = -1;
1191
1192         /* XXX should be pre-session */
1193         ssh_init_forwarding();
1194
1195         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1196                 id = ssh_session2_open();
1197
1198         /* If we don't expect to open a new session, then disallow it */
1199         if (options.control_master == SSHCTL_MASTER_NO &&
1200             (datafellows & SSH_NEW_OPENSSH)) {
1201                 debug("Requesting no-more-sessions@openssh.com");
1202                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1203                 packet_put_cstring("no-more-sessions@openssh.com");
1204                 packet_put_char(0);
1205                 packet_send();
1206         }
1207
1208         /* Execute a local command */
1209         if (options.local_command != NULL &&
1210             options.permit_local_command)
1211                 ssh_local_cmd(options.local_command);
1212
1213         /* Start listening for multiplex clients */
1214         muxserver_listen();
1215
1216         /* If requested, let ssh continue in the background. */
1217         if (fork_after_authentication_flag) {
1218                 fork_after_authentication_flag = 0;
1219                 if (daemon(1, 1) < 0)
1220                         fatal("daemon() failed: %.200s", strerror(errno));
1221         }
1222
1223         return client_loop(tty_flag, tty_flag ?
1224             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1225 }
1226
1227 static void
1228 load_public_identity_files(void)
1229 {
1230         char *filename, *cp, thishost[NI_MAXHOST];
1231         char *pwdir = NULL, *pwname = NULL;
1232         int i = 0;
1233         Key *public;
1234         struct passwd *pw;
1235 #ifdef SMARTCARD
1236         Key **keys;
1237
1238         if (options.smartcard_device != NULL &&
1239             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1240             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL) {
1241                 int count = 0;
1242                 for (i = 0; keys[i] != NULL; i++) {
1243                         count++;
1244                         memmove(&options.identity_files[1],
1245                             &options.identity_files[0],
1246                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1247                         memmove(&options.identity_keys[1],
1248                             &options.identity_keys[0],
1249                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1250                         options.num_identity_files++;
1251                         options.identity_keys[0] = keys[i];
1252                         options.identity_files[0] = sc_get_key_label(keys[i]);
1253                 }
1254                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1255                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1256                 i = count;
1257                 xfree(keys);
1258         }
1259 #endif /* SMARTCARD */
1260         if ((pw = getpwuid(original_real_uid)) == NULL)
1261                 fatal("load_public_identity_files: getpwuid failed");
1262         pwname = xstrdup(pw->pw_name);
1263         pwdir = xstrdup(pw->pw_dir);
1264         if (gethostname(thishost, sizeof(thishost)) == -1)
1265                 fatal("load_public_identity_files: gethostname: %s",
1266                     strerror(errno));
1267         for (; i < options.num_identity_files; i++) {
1268                 cp = tilde_expand_filename(options.identity_files[i],
1269                     original_real_uid);
1270                 filename = percent_expand(cp, "d", pwdir,
1271                     "u", pwname, "l", thishost, "h", host,
1272                     "r", options.user, (char *)NULL);
1273                 xfree(cp);
1274                 public = key_load_public(filename, NULL);
1275                 debug("identity file %s type %d", filename,
1276                     public ? public->type : -1);
1277                 xfree(options.identity_files[i]);
1278                 options.identity_files[i] = filename;
1279                 options.identity_keys[i] = public;
1280         }
1281         bzero(pwname, strlen(pwname));
1282         xfree(pwname);
1283         bzero(pwdir, strlen(pwdir));
1284         xfree(pwdir);
1285 }