ssh.c

   1 /* $OpenBSD: ssh.c,v 1.314 2008/06/10 22:15:23 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
  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.  This can be set on the command line. */
 111 int debug_flag = 0;
 112
 113 /* Flag indicating whether a tty should be allocated */
 114 int tty_flag = 0;
 115 int no_tty_flag = 0;
 116 int force_tty_flag = 0;
 117
 118 /* don't exec a shell */
 119 int no_shell_flag = 0;
 120
 121 /*
 122  * Flag indicating that nothing should be read from stdin.  This can be set
 123  * on the command line.
 124  */
 125 int stdin_null_flag = 0;
 126
 127 /*
 128  * Flag indicating that ssh should fork after authentication.  This is useful
 129  * so that the passphrase can be entered manually, and then ssh goes to the
 130  * background.
 131  */
 132 int fork_after_authentication_flag = 0;
 133
 134 /*
 135  * General data structure for command line options and options configurable
 136  * in configuration files.  See readconf.h.
 137  */
 138 Options options;
 139
 140 /* optional user configfile */
 141 char *config = NULL;
 142
 143 /*
 144  * Name of the host we are connecting to.  This is the name given on the
 145  * command line, or the HostName specified for the user-supplied name in a
 146  * configuration file.
 147  */
 148 char *host;
 149
 150 /* socket address the host resolves to */
 151 struct sockaddr_storage hostaddr;
 152
 153 /* Private host keys. */
 154 Sensitive sensitive_data;
 155
 156 /* Original real UID. */
 157 uid_t original_real_uid;
 158 uid_t original_effective_uid;
 159
 160 /* command to be executed */
 161 Buffer command;
 162
 163 /* Should we execute a command or invoke a subsystem? */
 164 int subsystem_flag = 0;
 165
 166 /* # of replies received for global requests */
 167 static int client_global_request_id = 0;
 168
 169 /* pid of proxycommand child process */
 170 pid_t proxy_command_pid = 0;
 171
 172 /* 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 [-1246AaCfgKkMNnqsTtVvXxY] [-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;
 207         char *p, *cp, *line, 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         /* Initialize option structure to indicate that no values have been set. */
 265         initialize_options(&options);
 266
 267         /* Parse command-line arguments. */
 268         host = NULL;
 269
 270  again:
 271         while ((opt = getopt(ac, av,
 272             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:KL:MNO:PR:S:TVw:XY")) != -1) {
 273                 switch (opt) {
 274                 case '1':
 275                         options.protocol = SSH_PROTO_1;
 276                         break;
 277                 case '2':
 278                         options.protocol = SSH_PROTO_2;
 279                         break;
 280                 case '4':
 281                         options.address_family = AF_INET;
 282                         break;
 283                 case '6':
 284                         options.address_family = AF_INET6;
 285                         break;
 286                 case 'n':
 287                         stdin_null_flag = 1;
 288                         break;
 289                 case 'f':
 290                         fork_after_authentication_flag = 1;
 291                         stdin_null_flag = 1;
 292                         break;
 293                 case 'x':
 294                         options.forward_x11 = 0;
 295                         break;
 296                 case 'X':
 297                         options.forward_x11 = 1;
 298                         break;
 299                 case 'Y':
 300                         options.forward_x11 = 1;
 301                         options.forward_x11_trusted = 1;
 302                         break;
 303                 case 'g':
 304                         options.gateway_ports = 1;
 305                         break;
 306                 case 'O':
 307                         if (strcmp(optarg, "check") == 0)
 308                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 309                         else if (strcmp(optarg, "exit") == 0)
 310                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 311                         else
 312                                 fatal("Invalid multiplex command.");
 313                         break;
 314                 case 'P':       /* deprecated */
 315                         options.use_privileged_port = 0;
 316                         break;
 317                 case 'a':
 318                         options.forward_agent = 0;
 319                         break;
 320                 case 'A':
 321                         options.forward_agent = 1;
 322                         break;
 323                 case 'k':
 324                         options.gss_deleg_creds = 0;
 325                         break;
 326                 case 'K':
 327                         options.gss_authentication = 1;
 328                         options.gss_deleg_creds = 1;
 329                         break;
 330                 case 'i':
 331                         if (stat(optarg, &st) < 0) {
 332                                 fprintf(stderr, "Warning: Identity file %s "
 333                                     "not accessible: %s.\n", optarg,
 334                                     strerror(errno));
 335                                 break;
 336                         }
 337                         if (options.num_identity_files >=
 338                             SSH_MAX_IDENTITY_FILES)
 339                                 fatal("Too many identity files specified "
 340                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 341                         options.identity_files[options.num_identity_files++] =
 342                             xstrdup(optarg);
 343                         break;
 344                 case 'I':
 345 #ifdef SMARTCARD
 346                         options.smartcard_device = xstrdup(optarg);
 347 #else
 348                         fprintf(stderr, "no support for smartcards.\n");
 349 #endif
 350                         break;
 351                 case 't':
 352                         if (tty_flag)
 353                                 force_tty_flag = 1;
 354                         tty_flag = 1;
 355                         break;
 356                 case 'v':
 357                         if (debug_flag == 0) {
 358                                 debug_flag = 1;
 359                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 360                         } else {
 361                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 362                                         options.log_level++;
 363                                 break;
 364                         }
 365                         /* FALLTHROUGH */
 366                 case 'V':
 367                         fprintf(stderr, "%s, %s\n",
 368                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 369                         if (opt == 'V')
 370                                 exit(0);
 371                         break;
 372                 case 'w':
 373                         if (options.tun_open == -1)
 374                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 375                         options.tun_local = a2tun(optarg, &options.tun_remote);
 376                         if (options.tun_local == SSH_TUNID_ERR) {
 377                                 fprintf(stderr, "Bad tun device '%s'\n", optarg);
 378                                 exit(255);
 379                         }
 380                         break;
 381                 case 'q':
 382                         options.log_level = SYSLOG_LEVEL_QUIET;
 383                         break;
 384                 case 'e':
 385                         if (optarg[0] == '^' && optarg[2] == 0 &&
 386                             (u_char) optarg[1] >= 64 &&
 387                             (u_char) optarg[1] < 128)
 388                                 options.escape_char = (u_char) optarg[1] & 31;
 389                         else if (strlen(optarg) == 1)
 390                                 options.escape_char = (u_char) optarg[0];
 391                         else if (strcmp(optarg, "none") == 0)
 392                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 393                         else {
 394                                 fprintf(stderr, "Bad escape character '%s'.\n",
 395                                     optarg);
 396                                 exit(255);
 397                         }
 398                         break;
 399                 case 'c':
 400                         if (ciphers_valid(optarg)) {
 401                                 /* SSH2 only */
 402                                 options.ciphers = xstrdup(optarg);
 403                                 options.cipher = SSH_CIPHER_INVALID;
 404                         } else {
 405                                 /* SSH1 only */
 406                                 options.cipher = cipher_number(optarg);
 407                                 if (options.cipher == -1) {
 408                                         fprintf(stderr,
 409                                             "Unknown cipher type '%s'\n",
 410                                             optarg);
 411                                         exit(255);
 412                                 }
 413                                 if (options.cipher == SSH_CIPHER_3DES)
 414                                         options.ciphers = "3des-cbc";
 415                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 416                                         options.ciphers = "blowfish-cbc";
 417                                 else
 418                                         options.ciphers = (char *)-1;
 419                         }
 420                         break;
 421                 case 'm':
 422                         if (mac_valid(optarg))
 423                                 options.macs = xstrdup(optarg);
 424                         else {
 425                                 fprintf(stderr, "Unknown mac type '%s'\n",
 426                                     optarg);
 427                                 exit(255);
 428                         }
 429                         break;
 430                 case 'M':
 431                         if (options.control_master == SSHCTL_MASTER_YES)
 432                                 options.control_master = SSHCTL_MASTER_ASK;
 433                         else
 434                                 options.control_master = SSHCTL_MASTER_YES;
 435                         break;
 436                 case 'p':
 437                         options.port = a2port(optarg);
 438                         if (options.port == 0) {
 439                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 440                                 exit(255);
 441                         }
 442                         break;
 443                 case 'l':
 444                         options.user = optarg;
 445                         break;
 446
 447                 case 'L':
 448                         if (parse_forward(&fwd, optarg))
 449                                 add_local_forward(&options, &fwd);
 450                         else {
 451                                 fprintf(stderr,
 452                                     "Bad local forwarding specification '%s'\n",
 453                                     optarg);
 454                                 exit(255);
 455                         }
 456                         break;
 457
 458                 case 'R':
 459                         if (parse_forward(&fwd, optarg)) {
 460                                 add_remote_forward(&options, &fwd);
 461                         } else {
 462                                 fprintf(stderr,
 463                                     "Bad remote forwarding specification "
 464                                     "'%s'\n", optarg);
 465                                 exit(255);
 466                         }
 467                         break;
 468
 469                 case 'D':
 470                         cp = p = xstrdup(optarg);
 471                         memset(&fwd, '\0', sizeof(fwd));
 472                         fwd.connect_host = "socks";
 473                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 474                                 fprintf(stderr, "Bad dynamic forwarding "
 475                                     "specification '%.100s'\n", optarg);
 476                                 exit(255);
 477                         }
 478                         if (cp != NULL) {
 479                                 fwd.listen_port = a2port(cp);
 480                                 fwd.listen_host = cleanhostname(fwd.listen_host);
 481                         } else {
 482                                 fwd.listen_port = a2port(fwd.listen_host);
 483                                 fwd.listen_host = NULL;
 484                         }
 485
 486                         if (fwd.listen_port == 0) {
 487                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 488                                     optarg);
 489                                 exit(255);
 490                         }
 491                         add_local_forward(&options, &fwd);
 492                         xfree(p);
 493                         break;
 494
 495                 case 'C':
 496                         options.compression = 1;
 497                         break;
 498                 case 'N':
 499                         no_shell_flag = 1;
 500                         no_tty_flag = 1;
 501                         break;
 502                 case 'T':
 503                         no_tty_flag = 1;
 504                         break;
 505                 case 'o':
 506                         dummy = 1;
 507                         line = xstrdup(optarg);
 508                         if (process_config_line(&options, host ? host : "",
 509                             line, "command-line", 0, &dummy) != 0)
 510                                 exit(255);
 511                         xfree(line);
 512                         break;
 513                 case 's':
 514                         subsystem_flag = 1;
 515                         break;
 516                 case 'S':
 517                         if (options.control_path != NULL)
 518                                 free(options.control_path);
 519                         options.control_path = xstrdup(optarg);
 520                         break;
 521                 case 'b':
 522                         options.bind_address = optarg;
 523                         break;
 524                 case 'F':
 525                         config = optarg;
 526                         break;
 527                 default:
 528                         usage();
 529                 }
 530         }
 531
 532         ac -= optind;
 533         av += optind;
 534
 535         if (ac > 0 && !host && **av != '-') {
 536                 if (strrchr(*av, '@')) {
 537                         p = xstrdup(*av);
 538                         cp = strrchr(p, '@');
 539                         if (cp == NULL || cp == p)
 540                                 usage();
 541                         options.user = p;
 542                         *cp = '\0';
 543                         host = ++cp;
 544                 } else
 545                         host = *av;
 546                 if (ac > 1) {
 547                         optind = optreset = 1;
 548                         goto again;
 549                 }
 550                 ac--, av++;
 551         }
 552
 553         /* Check that we got a host name. */
 554         if (!host)
 555                 usage();
 556
 557         SSLeay_add_all_algorithms();
 558         ERR_load_crypto_strings();
 559
 560         /* Initialize the command to execute on remote host. */
 561         buffer_init(&command);
 562
 563         /*
 564          * Save the command to execute on the remote host in a buffer. There
 565          * is no limit on the length of the command, except by the maximum
 566          * packet size.  Also sets the tty flag if there is no command.
 567          */
 568         if (!ac) {
 569                 /* No command specified - execute shell on a tty. */
 570                 tty_flag = 1;
 571                 if (subsystem_flag) {
 572                         fprintf(stderr,
 573                             "You must specify a subsystem to invoke.\n");
 574                         usage();
 575                 }
 576         } else {
 577                 /* A command has been specified.  Store it into the buffer. */
 578                 for (i = 0; i < ac; i++) {
 579                         if (i)
 580                                 buffer_append(&command, " ", 1);
 581                         buffer_append(&command, av[i], strlen(av[i]));
 582                 }
 583         }
 584
 585         /* Cannot fork to background if no command. */
 586         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 587                 fatal("Cannot fork into background without a command to execute.");
 588
 589         /* Allocate a tty by default if no command specified. */
 590         if (buffer_len(&command) == 0)
 591                 tty_flag = 1;
 592
 593         /* Force no tty */
 594         if (no_tty_flag)
 595                 tty_flag = 0;
 596         /* Do not allocate a tty if stdin is not a tty. */
 597         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 598                 if (tty_flag)
 599                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 600                 tty_flag = 0;
 601         }
 602
 603         /*
 604          * Initialize "log" output.  Since we are the client all output
 605          * actually goes to stderr.
 606          */
 607         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 608             SYSLOG_FACILITY_USER, 1);
 609
 610         /*
 611          * Read per-user configuration file.  Ignore the system wide config
 612          * file if the user specifies a config file on the command line.
 613          */
 614         if (config != NULL) {
 615                 if (!read_config_file(config, host, &options, 0))
 616                         fatal("Can't open user config file %.100s: "
 617                             "%.100s", config, strerror(errno));
 618         } else {
 619                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 620                     _PATH_SSH_USER_CONFFILE);
 621                 (void)read_config_file(buf, host, &options, 1);
 622
 623                 /* Read systemwide configuration file after use config. */
 624                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 625                     &options, 0);
 626         }
 627
 628         /* Fill configuration defaults. */
 629         fill_default_options(&options);
 630
 631         channel_set_af(options.address_family);
 632
 633         /* reinit */
 634         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 635
 636         seed_rng();
 637
 638         if (options.user == NULL)
 639                 options.user = xstrdup(pw->pw_name);
 640
 641         if (options.hostname != NULL)
 642                 host = options.hostname;
 643
 644         /* force lowercase for hostkey matching */
 645         if (options.host_key_alias != NULL) {
 646                 for (p = options.host_key_alias; *p; p++)
 647                         if (isupper(*p))
 648                                 *p = (char)tolower(*p);
 649         }
 650
 651         /* Get default port if port has not been set. */
 652         if (options.port == 0) {
 653                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 654                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 655         }
 656
 657         if (options.proxy_command != NULL &&
 658             strcmp(options.proxy_command, "none") == 0) {
 659                 xfree(options.proxy_command);
 660                 options.proxy_command = NULL;
 661         }
 662         if (options.control_path != NULL &&
 663             strcmp(options.control_path, "none") == 0) {
 664                 xfree(options.control_path);
 665                 options.control_path = NULL;
 666         }
 667
 668         if (options.control_path != NULL) {
 669                 char thishost[NI_MAXHOST];
 670
 671                 if (gethostname(thishost, sizeof(thishost)) == -1)
 672                         fatal("gethostname: %s", strerror(errno));
 673                 snprintf(buf, sizeof(buf), "%d", options.port);
 674                 cp = tilde_expand_filename(options.control_path,
 675                     original_real_uid);
 676                 xfree(options.control_path);
 677                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 678                     "r", options.user, "l", thishost, (char *)NULL);
 679                 xfree(cp);
 680         }
 681         if (muxclient_command != 0 && options.control_path == NULL)
 682                 fatal("No ControlPath specified for \"-O\" command");
 683         if (options.control_path != NULL)
 684                 muxclient(options.control_path);
 685
 686         timeout_ms = options.connection_timeout * 1000;
 687
 688         /* Open a connection to the remote host. */
 689         if (ssh_connect(host, &hostaddr, options.port,
 690             options.address_family, options.connection_attempts, &timeout_ms,
 691             options.tcp_keep_alive,
 692 #ifdef HAVE_CYGWIN
 693             options.use_privileged_port,
 694 #else
 695             original_effective_uid == 0 && options.use_privileged_port,
 696 #endif
 697             options.proxy_command) != 0)
 698                 exit(255);
 699
 700         if (timeout_ms > 0)
 701                 debug3("timeout: %d ms remain after connect", timeout_ms);
 702
 703         /*
 704          * If we successfully made the connection, load the host private key
 705          * in case we will need it later for combined rsa-rhosts
 706          * authentication. This must be done before releasing extra
 707          * privileges, because the file is only readable by root.
 708          * If we cannot access the private keys, load the public keys
 709          * instead and try to execute the ssh-keysign helper instead.
 710          */
 711         sensitive_data.nkeys = 0;
 712         sensitive_data.keys = NULL;
 713         sensitive_data.external_keysign = 0;
 714         if (options.rhosts_rsa_authentication ||
 715             options.hostbased_authentication) {
 716                 sensitive_data.nkeys = 3;
 717                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 718                     sizeof(Key));
 719
 720                 PRIV_START;
 721                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 722                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 723                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 724                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 725                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 726                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 727                 PRIV_END;
 728
 729                 if (options.hostbased_authentication == 1 &&
 730                     sensitive_data.keys[0] == NULL &&
 731                     sensitive_data.keys[1] == NULL &&
 732                     sensitive_data.keys[2] == NULL) {
 733                         sensitive_data.keys[1] = key_load_public(
 734                             _PATH_HOST_DSA_KEY_FILE, NULL);
 735                         sensitive_data.keys[2] = key_load_public(
 736                             _PATH_HOST_RSA_KEY_FILE, NULL);
 737                         sensitive_data.external_keysign = 1;
 738                 }
 739         }
 740         /*
 741          * Get rid of any extra privileges that we may have.  We will no
 742          * longer need them.  Also, extra privileges could make it very hard
 743          * to read identity files and other non-world-readable files from the
 744          * user's home directory if it happens to be on a NFS volume where
 745          * root is mapped to nobody.
 746          */
 747         if (original_effective_uid == 0) {
 748                 PRIV_START;
 749                 permanently_set_uid(pw);
 750         }
 751
 752         /*
 753          * Now that we are back to our own permissions, create ~/.ssh
 754          * directory if it doesn't already exist.
 755          */
 756         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 757         if (stat(buf, &st) < 0)
 758                 if (mkdir(buf, 0700) < 0)
 759                         error("Could not create directory '%.200s'.", buf);
 760
 761         /* load options.identity_files */
 762         load_public_identity_files();
 763
 764         /* Expand ~ in known host file names. */
 765         /* XXX mem-leaks: */
 766         options.system_hostfile =
 767             tilde_expand_filename(options.system_hostfile, original_real_uid);
 768         options.user_hostfile =
 769             tilde_expand_filename(options.user_hostfile, original_real_uid);
 770         options.system_hostfile2 =
 771             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 772         options.user_hostfile2 =
 773             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 774
 775         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 776
 777         /* Log into the remote system.  This never returns if the login fails. */
 778         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 779             pw, timeout_ms);
 780
 781         /* We no longer need the private host keys.  Clear them now. */
 782         if (sensitive_data.nkeys != 0) {
 783                 for (i = 0; i < sensitive_data.nkeys; i++) {
 784                         if (sensitive_data.keys[i] != NULL) {
 785                                 /* Destroys contents safely */
 786                                 debug3("clear hostkey %d", i);
 787                                 key_free(sensitive_data.keys[i]);
 788                                 sensitive_data.keys[i] = NULL;
 789                         }
 790                 }
 791                 xfree(sensitive_data.keys);
 792         }
 793         for (i = 0; i < options.num_identity_files; i++) {
 794                 if (options.identity_files[i]) {
 795                         xfree(options.identity_files[i]);
 796                         options.identity_files[i] = NULL;
 797                 }
 798                 if (options.identity_keys[i]) {
 799                         key_free(options.identity_keys[i]);
 800                         options.identity_keys[i] = NULL;
 801                 }
 802         }
 803
 804         exit_status = compat20 ? ssh_session2() : ssh_session();
 805         packet_close();
 806
 807         if (options.control_path != NULL && muxserver_sock != -1)
 808                 unlink(options.control_path);
 809
 810         /*
 811          * Send SIGHUP to proxy command if used. We don't wait() in
 812          * case it hangs and instead rely on init to reap the child
 813          */
 814         if (proxy_command_pid > 1)
 815                 kill(proxy_command_pid, SIGHUP);
 816
 817         return exit_status;
 818 }
 819
 820 static void
 821 ssh_init_forwarding(void)
 822 {
 823         int success = 0;
 824         int i;
 825
 826         /* Initiate local TCP/IP port forwardings. */
 827         for (i = 0; i < options.num_local_forwards; i++) {
 828                 debug("Local connections to %.200s:%d forwarded to remote "
 829                     "address %.200s:%d",
 830                     (options.local_forwards[i].listen_host == NULL) ?
 831                     (options.gateway_ports ? "*" : "LOCALHOST") :
 832                     options.local_forwards[i].listen_host,
 833                     options.local_forwards[i].listen_port,
 834                     options.local_forwards[i].connect_host,
 835                     options.local_forwards[i].connect_port);
 836                 success += channel_setup_local_fwd_listener(
 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                     options.gateway_ports);
 842         }
 843         if (i > 0 && success != i && options.exit_on_forward_failure)
 844                 fatal("Could not request local forwarding.");
 845         if (i > 0 && success == 0)
 846                 error("Could not request local forwarding.");
 847
 848         /* Initiate remote TCP/IP port forwardings. */
 849         for (i = 0; i < options.num_remote_forwards; i++) {
 850                 debug("Remote connections from %.200s:%d forwarded to "
 851                     "local address %.200s:%d",
 852                     (options.remote_forwards[i].listen_host == NULL) ?
 853                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 854                     options.remote_forwards[i].listen_port,
 855                     options.remote_forwards[i].connect_host,
 856                     options.remote_forwards[i].connect_port);
 857                 if (channel_request_remote_forwarding(
 858                     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) < 0) {
 862                         if (options.exit_on_forward_failure)
 863                                 fatal("Could not request remote forwarding.");
 864                         else
 865                                 logit("Warning: Could not request remote "
 866                                     "forwarding.");
 867                 }
 868         }
 869
 870         /* Initiate tunnel forwarding. */
 871         if (options.tun_open != SSH_TUNMODE_NO) {
 872                 if (client_request_tun_fwd(options.tun_open,
 873                     options.tun_local, options.tun_remote) == -1) {
 874                         if (options.exit_on_forward_failure)
 875                                 fatal("Could not request tunnel forwarding.");
 876                         else
 877                                 error("Could not request tunnel forwarding.");
 878                 }
 879         }
 880 }
 881
 882 static void
 883 check_agent_present(void)
 884 {
 885         if (options.forward_agent) {
 886                 /* Clear agent forwarding if we don't have an agent. */
 887                 if (!ssh_agent_present())
 888                         options.forward_agent = 0;
 889         }
 890 }
 891
 892 static int
 893 ssh_session(void)
 894 {
 895         int type;
 896         int interactive = 0;
 897         int have_tty = 0;
 898         struct winsize ws;
 899         char *cp;
 900         const char *display;
 901
 902         /* Enable compression if requested. */
 903         if (options.compression) {
 904                 debug("Requesting compression at level %d.", options.compression_level);
 905
 906                 if (options.compression_level < 1 || options.compression_level > 9)
 907                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 908
 909                 /* Send the request. */
 910                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 911                 packet_put_int(options.compression_level);
 912                 packet_send();
 913                 packet_write_wait();
 914                 type = packet_read();
 915                 if (type == SSH_SMSG_SUCCESS)
 916                         packet_start_compression(options.compression_level);
 917                 else if (type == SSH_SMSG_FAILURE)
 918                         logit("Warning: Remote host refused compression.");
 919                 else
 920                         packet_disconnect("Protocol error waiting for compression response.");
 921         }
 922         /* Allocate a pseudo tty if appropriate. */
 923         if (tty_flag) {
 924                 debug("Requesting pty.");
 925
 926                 /* Start the packet. */
 927                 packet_start(SSH_CMSG_REQUEST_PTY);
 928
 929                 /* Store TERM in the packet.  There is no limit on the
 930                    length of the string. */
 931                 cp = getenv("TERM");
 932                 if (!cp)
 933                         cp = "";
 934                 packet_put_cstring(cp);
 935
 936                 /* Store window size in the packet. */
 937                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 938                         memset(&ws, 0, sizeof(ws));
 939                 packet_put_int((u_int)ws.ws_row);
 940                 packet_put_int((u_int)ws.ws_col);
 941                 packet_put_int((u_int)ws.ws_xpixel);
 942                 packet_put_int((u_int)ws.ws_ypixel);
 943
 944                 /* Store tty modes in the packet. */
 945                 tty_make_modes(fileno(stdin), NULL);
 946
 947                 /* Send the packet, and wait for it to leave. */
 948                 packet_send();
 949                 packet_write_wait();
 950
 951                 /* Read response from the server. */
 952                 type = packet_read();
 953                 if (type == SSH_SMSG_SUCCESS) {
 954                         interactive = 1;
 955                         have_tty = 1;
 956                 } else if (type == SSH_SMSG_FAILURE)
 957                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 958                 else
 959                         packet_disconnect("Protocol error waiting for pty request response.");
 960         }
 961         /* Request X11 forwarding if enabled and DISPLAY is set. */
 962         display = getenv("DISPLAY");
 963         if (options.forward_x11 && display != NULL) {
 964                 char *proto, *data;
 965                 /* Get reasonable local authentication information. */
 966                 client_x11_get_proto(display, options.xauth_location,
 967                     options.forward_x11_trusted, &proto, &data);
 968                 /* Request forwarding with authentication spoofing. */
 969                 debug("Requesting X11 forwarding with authentication spoofing.");
 970                 x11_request_forwarding_with_spoofing(0, display, proto, data);
 971
 972                 /* Read response from the server. */
 973                 type = packet_read();
 974                 if (type == SSH_SMSG_SUCCESS) {
 975                         interactive = 1;
 976                 } else if (type == SSH_SMSG_FAILURE) {
 977                         logit("Warning: Remote host denied X11 forwarding.");
 978                 } else {
 979                         packet_disconnect("Protocol error waiting for X11 forwarding");
 980                 }
 981         }
 982         /* Tell the packet module whether this is an interactive session. */
 983         packet_set_interactive(interactive);
 984
 985         /* Request authentication agent forwarding if appropriate. */
 986         check_agent_present();
 987
 988         if (options.forward_agent) {
 989                 debug("Requesting authentication agent forwarding.");
 990                 auth_request_forwarding();
 991
 992                 /* Read response from the server. */
 993                 type = packet_read();
 994                 packet_check_eom();
 995                 if (type != SSH_SMSG_SUCCESS)
 996                         logit("Warning: Remote host denied authentication agent forwarding.");
 997         }
 998
 999         /* Initiate port forwardings. */
1000         ssh_init_forwarding();
1001
1002         /* Execute a local command */
1003         if (options.local_command != NULL &&
1004             options.permit_local_command)
1005                 ssh_local_cmd(options.local_command);
1006
1007         /* If requested, let ssh continue in the background. */
1008         if (fork_after_authentication_flag)
1009                 if (daemon(1, 1) < 0)
1010                         fatal("daemon() failed: %.200s", strerror(errno));
1011
1012         /*
1013          * If a command was specified on the command line, execute the
1014          * command now. Otherwise request the server to start a shell.
1015          */
1016         if (buffer_len(&command) > 0) {
1017                 int len = buffer_len(&command);
1018                 if (len > 900)
1019                         len = 900;
1020                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1021                 packet_start(SSH_CMSG_EXEC_CMD);
1022                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1023                 packet_send();
1024                 packet_write_wait();
1025         } else {
1026                 debug("Requesting shell.");
1027                 packet_start(SSH_CMSG_EXEC_SHELL);
1028                 packet_send();
1029                 packet_write_wait();
1030         }
1031
1032         /* Enter the interactive session. */
1033         return client_loop(have_tty, tty_flag ?
1034             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1035 }
1036
1037 void
1038 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1039 {
1040         int i;
1041
1042         i = client_global_request_id++;
1043         if (i >= options.num_remote_forwards)
1044                 return;
1045         debug("remote forward %s for: listen %d, connect %s:%d",
1046             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1047             options.remote_forwards[i].listen_port,
1048             options.remote_forwards[i].connect_host,
1049             options.remote_forwards[i].connect_port);
1050         if (type == SSH2_MSG_REQUEST_FAILURE) {
1051                 if (options.exit_on_forward_failure)
1052                         fatal("Error: remote port forwarding failed for "
1053                             "listen port %d",
1054                             options.remote_forwards[i].listen_port);
1055                 else
1056                         logit("Warning: remote port forwarding failed for "
1057                             "listen port %d",
1058                             options.remote_forwards[i].listen_port);
1059         }
1060 }
1061
1062 /* request pty/x11/agent/tcpfwd/shell for channel */
1063 static void
1064 ssh_session2_setup(int id, void *arg)
1065 {
1066         extern char **environ;
1067         const char *display;
1068         int interactive = tty_flag;
1069
1070         display = getenv("DISPLAY");
1071         if (options.forward_x11 && display != NULL) {
1072                 char *proto, *data;
1073                 /* Get reasonable local authentication information. */
1074                 client_x11_get_proto(display, options.xauth_location,
1075                     options.forward_x11_trusted, &proto, &data);
1076                 /* Request forwarding with authentication spoofing. */
1077                 debug("Requesting X11 forwarding with authentication spoofing.");
1078                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1079                 interactive = 1;
1080                 /* XXX wait for reply */
1081         }
1082
1083         check_agent_present();
1084         if (options.forward_agent) {
1085                 debug("Requesting authentication agent forwarding.");
1086                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1087                 packet_send();
1088         }
1089
1090         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1091             NULL, fileno(stdin), &command, environ);
1092
1093         packet_set_interactive(interactive);
1094 }
1095
1096 /* open new channel for a session */
1097 static int
1098 ssh_session2_open(void)
1099 {
1100         Channel *c;
1101         int window, packetmax, in, out, err;
1102
1103         if (stdin_null_flag) {
1104                 in = open(_PATH_DEVNULL, O_RDONLY);
1105         } else {
1106                 in = dup(STDIN_FILENO);
1107         }
1108         out = dup(STDOUT_FILENO);
1109         err = dup(STDERR_FILENO);
1110
1111         if (in < 0 || out < 0 || err < 0)
1112                 fatal("dup() in/out/err failed");
1113
1114         /* enable nonblocking unless tty */
1115         if (!isatty(in))
1116                 set_nonblock(in);
1117         if (!isatty(out))
1118                 set_nonblock(out);
1119         if (!isatty(err))
1120                 set_nonblock(err);
1121
1122         window = CHAN_SES_WINDOW_DEFAULT;
1123         packetmax = CHAN_SES_PACKET_DEFAULT;
1124         if (tty_flag) {
1125                 window >>= 1;
1126                 packetmax >>= 1;
1127         }
1128         c = channel_new(
1129             "session", SSH_CHANNEL_OPENING, in, out, err,
1130             window, packetmax, CHAN_EXTENDED_WRITE,
1131             "client-session", /*nonblock*/0);
1132
1133         debug3("ssh_session2_open: channel_new: %d", c->self);
1134
1135         channel_send_open(c->self);
1136         if (!no_shell_flag)
1137                 channel_register_open_confirm(c->self,
1138                     ssh_session2_setup, NULL);
1139
1140         return c->self;
1141 }
1142
1143 static int
1144 ssh_session2(void)
1145 {
1146         int id = -1;
1147
1148         /* XXX should be pre-session */
1149         ssh_init_forwarding();
1150
1151         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1152                 id = ssh_session2_open();
1153
1154         /* If we don't expect to open a new session, then disallow it */
1155         if (options.control_master == SSHCTL_MASTER_NO) {
1156                 debug("Requesting no-more-sessions@openssh.com");
1157                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1158                 packet_put_cstring("no-more-sessions@openssh.com");
1159                 packet_put_char(0);
1160                 packet_send();
1161         }
1162
1163         /* Execute a local command */
1164         if (options.local_command != NULL &&
1165             options.permit_local_command)
1166                 ssh_local_cmd(options.local_command);
1167
1168         /* Start listening for multiplex clients */
1169         muxserver_listen();
1170
1171         /* If requested, let ssh continue in the background. */
1172         if (fork_after_authentication_flag)
1173                 if (daemon(1, 1) < 0)
1174                         fatal("daemon() failed: %.200s", strerror(errno));
1175
1176         return client_loop(tty_flag, tty_flag ?
1177             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1178 }
1179
1180 static void
1181 load_public_identity_files(void)
1182 {
1183         char *filename, *cp, thishost[NI_MAXHOST];
1184         char *pwdir = NULL, *pwname = NULL;
1185         int i = 0;
1186         Key *public;
1187         struct passwd *pw;
1188 #ifdef SMARTCARD
1189         Key **keys;
1190
1191         if (options.smartcard_device != NULL &&
1192             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1193             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL) {
1194                 int count = 0;
1195                 for (i = 0; keys[i] != NULL; i++) {
1196                         count++;
1197                         memmove(&options.identity_files[1], &options.identity_files[0],
1198                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1199                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1200                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1201                         options.num_identity_files++;
1202                         options.identity_keys[0] = keys[i];
1203                         options.identity_files[0] = sc_get_key_label(keys[i]);
1204                 }
1205                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1206                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1207                 i = count;
1208                 xfree(keys);
1209         }
1210 #endif /* SMARTCARD */
1211         if ((pw = getpwuid(original_real_uid)) == NULL)
1212                 fatal("load_public_identity_files: getpwuid failed");
1213         pwname = xstrdup(pw->pw_name);
1214         pwdir = xstrdup(pw->pw_dir);
1215         if (gethostname(thishost, sizeof(thishost)) == -1)
1216                 fatal("load_public_identity_files: gethostname: %s",
1217                     strerror(errno));
1218         for (; i < options.num_identity_files; i++) {
1219                 cp = tilde_expand_filename(options.identity_files[i],
1220                     original_real_uid);
1221                 filename = percent_expand(cp, "d", pwdir,
1222                     "u", pwname, "l", thishost, "h", host,
1223                     "r", options.user, (char *)NULL);
1224                 xfree(cp);
1225                 public = key_load_public(filename, NULL);
1226                 debug("identity file %s type %d", filename,
1227                     public ? public->type : -1);
1228                 xfree(options.identity_files[i]);
1229                 options.identity_files[i] = filename;
1230                 options.identity_keys[i] = public;
1231         }
1232         bzero(pwname, strlen(pwname));
1233         xfree(pwname);
1234         bzero(pwdir, strlen(pwdir));
1235         xfree(pwdir);
1236 }