crypto/openssh-5/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.318 2008/07/02 13:47:39 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.  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 [-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         /*
 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
 273  again:
 274         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 275             "ACD:F:I:KL:MNO:PR:S:TVw:XY")) != -1) {
 276                 switch (opt) {
 277                 case '1':
 278                         options.protocol = SSH_PROTO_1;
 279                         break;
 280                 case '2':
 281                         options.protocol = SSH_PROTO_2;
 282                         break;
 283                 case '4':
 284                         options.address_family = AF_INET;
 285                         break;
 286                 case '6':
 287                         options.address_family = AF_INET6;
 288                         break;
 289                 case 'n':
 290                         stdin_null_flag = 1;
 291                         break;
 292                 case 'f':
 293                         fork_after_authentication_flag = 1;
 294                         stdin_null_flag = 1;
 295                         break;
 296                 case 'x':
 297                         options.forward_x11 = 0;
 298                         break;
 299                 case 'X':
 300                         options.forward_x11 = 1;
 301                         break;
 302                 case 'Y':
 303                         options.forward_x11 = 1;
 304                         options.forward_x11_trusted = 1;
 305                         break;
 306                 case 'g':
 307                         options.gateway_ports = 1;
 308                         break;
 309                 case 'O':
 310                         if (strcmp(optarg, "check") == 0)
 311                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 312                         else if (strcmp(optarg, "exit") == 0)
 313                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 314                         else
 315                                 fatal("Invalid multiplex command.");
 316                         break;
 317                 case 'P':       /* deprecated */
 318                         options.use_privileged_port = 0;
 319                         break;
 320                 case 'a':
 321                         options.forward_agent = 0;
 322                         break;
 323                 case 'A':
 324                         options.forward_agent = 1;
 325                         break;
 326                 case 'k':
 327                         options.gss_deleg_creds = 0;
 328                         break;
 329                 case 'K':
 330                         options.gss_authentication = 1;
 331                         options.gss_deleg_creds = 1;
 332                         break;
 333                 case 'i':
 334                         if (stat(optarg, &st) < 0) {
 335                                 fprintf(stderr, "Warning: Identity file %s "
 336                                     "not accessible: %s.\n", optarg,
 337                                     strerror(errno));
 338                                 break;
 339                         }
 340                         if (options.num_identity_files >=
 341                             SSH_MAX_IDENTITY_FILES)
 342                                 fatal("Too many identity files specified "
 343                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 344                         options.identity_files[options.num_identity_files++] =
 345                             xstrdup(optarg);
 346                         break;
 347                 case 'I':
 348 #ifdef SMARTCARD
 349                         options.smartcard_device = xstrdup(optarg);
 350 #else
 351                         fprintf(stderr, "no support for smartcards.\n");
 352 #endif
 353                         break;
 354                 case 't':
 355                         if (tty_flag)
 356                                 force_tty_flag = 1;
 357                         tty_flag = 1;
 358                         break;
 359                 case 'v':
 360                         if (debug_flag == 0) {
 361                                 debug_flag = 1;
 362                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 363                         } else {
 364                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 365                                         options.log_level++;
 366                                 break;
 367                         }
 368                         /* FALLTHROUGH */
 369                 case 'V':
 370                         fprintf(stderr, "%s, %s\n",
 371                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 372                         if (opt == 'V')
 373                                 exit(0);
 374                         break;
 375                 case 'w':
 376                         if (options.tun_open == -1)
 377                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 378                         options.tun_local = a2tun(optarg, &options.tun_remote);
 379                         if (options.tun_local == SSH_TUNID_ERR) {
 380                                 fprintf(stderr,
 381                                     "Bad tun device '%s'\n", optarg);
 382                                 exit(255);
 383                         }
 384                         break;
 385                 case 'q':
 386                         options.log_level = SYSLOG_LEVEL_QUIET;
 387                         break;
 388                 case 'e':
 389                         if (optarg[0] == '^' && optarg[2] == 0 &&
 390                             (u_char) optarg[1] >= 64 &&
 391                             (u_char) optarg[1] < 128)
 392                                 options.escape_char = (u_char) optarg[1] & 31;
 393                         else if (strlen(optarg) == 1)
 394                                 options.escape_char = (u_char) optarg[0];
 395                         else if (strcmp(optarg, "none") == 0)
 396                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 397                         else {
 398                                 fprintf(stderr, "Bad escape character '%s'.\n",
 399                                     optarg);
 400                                 exit(255);
 401                         }
 402                         break;
 403                 case 'c':
 404                         if (ciphers_valid(optarg)) {
 405                                 /* SSH2 only */
 406                                 options.ciphers = xstrdup(optarg);
 407                                 options.cipher = SSH_CIPHER_INVALID;
 408                         } else {
 409                                 /* SSH1 only */
 410                                 options.cipher = cipher_number(optarg);
 411                                 if (options.cipher == -1) {
 412                                         fprintf(stderr,
 413                                             "Unknown cipher type '%s'\n",
 414                                             optarg);
 415                                         exit(255);
 416                                 }
 417                                 if (options.cipher == SSH_CIPHER_3DES)
 418                                         options.ciphers = "3des-cbc";
 419                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 420                                         options.ciphers = "blowfish-cbc";
 421                                 else
 422                                         options.ciphers = (char *)-1;
 423                         }
 424                         break;
 425                 case 'm':
 426                         if (mac_valid(optarg))
 427                                 options.macs = xstrdup(optarg);
 428                         else {
 429                                 fprintf(stderr, "Unknown mac type '%s'\n",
 430                                     optarg);
 431                                 exit(255);
 432                         }
 433                         break;
 434                 case 'M':
 435                         if (options.control_master == SSHCTL_MASTER_YES)
 436                                 options.control_master = SSHCTL_MASTER_ASK;
 437                         else
 438                                 options.control_master = SSHCTL_MASTER_YES;
 439                         break;
 440                 case 'p':
 441                         options.port = a2port(optarg);
 442                         if (options.port == 0) {
 443                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 444                                 exit(255);
 445                         }
 446                         break;
 447                 case 'l':
 448                         options.user = optarg;
 449                         break;
 450
 451                 case 'L':
 452                         if (parse_forward(&fwd, optarg))
 453                                 add_local_forward(&options, &fwd);
 454                         else {
 455                                 fprintf(stderr,
 456                                     "Bad local forwarding specification '%s'\n",
 457                                     optarg);
 458                                 exit(255);
 459                         }
 460                         break;
 461
 462                 case 'R':
 463                         if (parse_forward(&fwd, optarg)) {
 464                                 add_remote_forward(&options, &fwd);
 465                         } else {
 466                                 fprintf(stderr,
 467                                     "Bad remote forwarding specification "
 468                                     "'%s'\n", optarg);
 469                                 exit(255);
 470                         }
 471                         break;
 472
 473                 case 'D':
 474                         cp = p = xstrdup(optarg);
 475                         memset(&fwd, '\0', sizeof(fwd));
 476                         fwd.connect_host = "socks";
 477                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 478                                 fprintf(stderr, "Bad dynamic forwarding "
 479                                     "specification '%.100s'\n", optarg);
 480                                 exit(255);
 481                         }
 482                         if (cp != NULL) {
 483                                 fwd.listen_port = a2port(cp);
 484                                 fwd.listen_host =
 485                                     cleanhostname(fwd.listen_host);
 486                         } else {
 487                                 fwd.listen_port = a2port(fwd.listen_host);
 488                                 fwd.listen_host = NULL;
 489                         }
 490
 491                         if (fwd.listen_port == 0) {
 492                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 493                                     optarg);
 494                                 exit(255);
 495                         }
 496                         add_local_forward(&options, &fwd);
 497                         xfree(p);
 498                         break;
 499
 500                 case 'C':
 501                         options.compression = 1;
 502                         break;
 503                 case 'N':
 504                         no_shell_flag = 1;
 505                         no_tty_flag = 1;
 506                         break;
 507                 case 'T':
 508                         no_tty_flag = 1;
 509                         break;
 510                 case 'o':
 511                         dummy = 1;
 512                         line = xstrdup(optarg);
 513                         if (process_config_line(&options, host ? host : "",
 514                             line, "command-line", 0, &dummy) != 0)
 515                                 exit(255);
 516                         xfree(line);
 517                         break;
 518                 case 's':
 519                         subsystem_flag = 1;
 520                         break;
 521                 case 'S':
 522                         if (options.control_path != NULL)
 523                                 free(options.control_path);
 524                         options.control_path = xstrdup(optarg);
 525                         break;
 526                 case 'b':
 527                         options.bind_address = optarg;
 528                         break;
 529                 case 'F':
 530                         config = optarg;
 531                         break;
 532                 default:
 533                         usage();
 534                 }
 535         }
 536
 537         ac -= optind;
 538         av += optind;
 539
 540         if (ac > 0 && !host && **av != '-') {
 541                 if (strrchr(*av, '@')) {
 542                         p = xstrdup(*av);
 543                         cp = strrchr(p, '@');
 544                         if (cp == NULL || cp == p)
 545                                 usage();
 546                         options.user = p;
 547                         *cp = '\0';
 548                         host = ++cp;
 549                 } else
 550                         host = *av;
 551                 if (ac > 1) {
 552                         optind = optreset = 1;
 553                         goto again;
 554                 }
 555                 ac--, av++;
 556         }
 557
 558         /* Check that we got a host name. */
 559         if (!host)
 560                 usage();
 561
 562         SSLeay_add_all_algorithms();
 563         ERR_load_crypto_strings();
 564
 565         /* Initialize the command to execute on remote host. */
 566         buffer_init(&command);
 567
 568         /*
 569          * Save the command to execute on the remote host in a buffer. There
 570          * is no limit on the length of the command, except by the maximum
 571          * packet size.  Also sets the tty flag if there is no command.
 572          */
 573         if (!ac) {
 574                 /* No command specified - execute shell on a tty. */
 575                 tty_flag = 1;
 576                 if (subsystem_flag) {
 577                         fprintf(stderr,
 578                             "You must specify a subsystem to invoke.\n");
 579                         usage();
 580                 }
 581         } else {
 582                 /* A command has been specified.  Store it into the buffer. */
 583                 for (i = 0; i < ac; i++) {
 584                         if (i)
 585                                 buffer_append(&command, " ", 1);
 586                         buffer_append(&command, av[i], strlen(av[i]));
 587                 }
 588         }
 589
 590         /* Cannot fork to background if no command. */
 591         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 592             !no_shell_flag)
 593                 fatal("Cannot fork into background without a command "
 594                     "to execute.");
 595
 596         /* Allocate a tty by default if no command specified. */
 597         if (buffer_len(&command) == 0)
 598                 tty_flag = 1;
 599
 600         /* Force no tty */
 601         if (no_tty_flag)
 602                 tty_flag = 0;
 603         /* Do not allocate a tty if stdin is not a tty. */
 604         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 605                 if (tty_flag)
 606                         logit("Pseudo-terminal will not be allocated because "
 607                             "stdin is not a terminal.");
 608                 tty_flag = 0;
 609         }
 610
 611         /*
 612          * Initialize "log" output.  Since we are the client all output
 613          * actually goes to stderr.
 614          */
 615         log_init(av[0],
 616             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 617             SYSLOG_FACILITY_USER, 1);
 618
 619         /*
 620          * Read per-user configuration file.  Ignore the system wide config
 621          * file if the user specifies a config file on the command line.
 622          */
 623         if (config != NULL) {
 624                 if (!read_config_file(config, host, &options, 0))
 625                         fatal("Can't open user config file %.100s: "
 626                             "%.100s", config, strerror(errno));
 627         } else {
 628                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 629                     _PATH_SSH_USER_CONFFILE);
 630                 (void)read_config_file(buf, host, &options, 1);
 631
 632                 /* Read systemwide configuration file after use config. */
 633                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 634                     &options, 0);
 635         }
 636
 637         /* Fill configuration defaults. */
 638         fill_default_options(&options);
 639
 640         channel_set_af(options.address_family);
 641
 642         /* reinit */
 643         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 644
 645         seed_rng();
 646
 647         if (options.user == NULL)
 648                 options.user = xstrdup(pw->pw_name);
 649
 650         /* Get default port if port has not been set. */
 651         if (options.port == 0) {
 652                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 653                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 654         }
 655
 656         if (options.local_command != NULL) {
 657                 char thishost[NI_MAXHOST];
 658
 659                 if (gethostname(thishost, sizeof(thishost)) == -1)
 660                         fatal("gethostname: %s", strerror(errno));
 661                 snprintf(buf, sizeof(buf), "%d", options.port);
 662                 debug3("expanding LocalCommand: %s", options.local_command);
 663                 cp = options.local_command;
 664                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 665                     "h", options.hostname? options.hostname : host,
 666                     "l", thishost, "n", host, "r", options.user, "p", buf,
 667                     "u", pw->pw_name, (char *)NULL);
 668                 debug3("expanded LocalCommand: %s", options.local_command);
 669                 xfree(cp);
 670         }
 671
 672         if (options.hostname != NULL)
 673                 host = options.hostname;
 674
 675         /* force lowercase for hostkey matching */
 676         if (options.host_key_alias != NULL) {
 677                 for (p = options.host_key_alias; *p; p++)
 678                         if (isupper(*p))
 679                                 *p = (char)tolower(*p);
 680         }
 681
 682         if (options.proxy_command != NULL &&
 683             strcmp(options.proxy_command, "none") == 0) {
 684                 xfree(options.proxy_command);
 685                 options.proxy_command = NULL;
 686         }
 687         if (options.control_path != NULL &&
 688             strcmp(options.control_path, "none") == 0) {
 689                 xfree(options.control_path);
 690                 options.control_path = NULL;
 691         }
 692
 693         if (options.control_path != NULL) {
 694                 char thishost[NI_MAXHOST];
 695
 696                 if (gethostname(thishost, sizeof(thishost)) == -1)
 697                         fatal("gethostname: %s", strerror(errno));
 698                 snprintf(buf, sizeof(buf), "%d", options.port);
 699                 cp = tilde_expand_filename(options.control_path,
 700                     original_real_uid);
 701                 xfree(options.control_path);
 702                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 703                     "r", options.user, "l", thishost, (char *)NULL);
 704                 xfree(cp);
 705         }
 706         if (muxclient_command != 0 && options.control_path == NULL)
 707                 fatal("No ControlPath specified for \"-O\" command");
 708         if (options.control_path != NULL)
 709                 muxclient(options.control_path);
 710
 711         timeout_ms = options.connection_timeout * 1000;
 712
 713         /* Open a connection to the remote host. */
 714         if (ssh_connect(host, &hostaddr, options.port,
 715             options.address_family, options.connection_attempts, &timeout_ms,
 716             options.tcp_keep_alive,
 717 #ifdef HAVE_CYGWIN
 718             options.use_privileged_port,
 719 #else
 720             original_effective_uid == 0 && options.use_privileged_port,
 721 #endif
 722             options.proxy_command) != 0)
 723                 exit(255);
 724
 725         if (timeout_ms > 0)
 726                 debug3("timeout: %d ms remain after connect", timeout_ms);
 727
 728         /*
 729          * If we successfully made the connection, load the host private key
 730          * in case we will need it later for combined rsa-rhosts
 731          * authentication. This must be done before releasing extra
 732          * privileges, because the file is only readable by root.
 733          * If we cannot access the private keys, load the public keys
 734          * instead and try to execute the ssh-keysign helper instead.
 735          */
 736         sensitive_data.nkeys = 0;
 737         sensitive_data.keys = NULL;
 738         sensitive_data.external_keysign = 0;
 739         if (options.rhosts_rsa_authentication ||
 740             options.hostbased_authentication) {
 741                 sensitive_data.nkeys = 3;
 742                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 743                     sizeof(Key));
 744
 745                 PRIV_START;
 746                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 747                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 748                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 749                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 750                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 751                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 752                 PRIV_END;
 753
 754                 if (options.hostbased_authentication == 1 &&
 755                     sensitive_data.keys[0] == NULL &&
 756                     sensitive_data.keys[1] == NULL &&
 757                     sensitive_data.keys[2] == NULL) {
 758                         sensitive_data.keys[1] = key_load_public(
 759                             _PATH_HOST_DSA_KEY_FILE, NULL);
 760                         sensitive_data.keys[2] = key_load_public(
 761                             _PATH_HOST_RSA_KEY_FILE, NULL);
 762                         sensitive_data.external_keysign = 1;
 763                 }
 764         }
 765         /*
 766          * Get rid of any extra privileges that we may have.  We will no
 767          * longer need them.  Also, extra privileges could make it very hard
 768          * to read identity files and other non-world-readable files from the
 769          * user's home directory if it happens to be on a NFS volume where
 770          * root is mapped to nobody.
 771          */
 772         if (original_effective_uid == 0) {
 773                 PRIV_START;
 774                 permanently_set_uid(pw);
 775         }
 776
 777         /*
 778          * Now that we are back to our own permissions, create ~/.ssh
 779          * directory if it doesn't already exist.
 780          */
 781         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir,
 782             strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 783         if (stat(buf, &st) < 0)
 784                 if (mkdir(buf, 0700) < 0)
 785                         error("Could not create directory '%.200s'.", buf);
 786
 787         /* load options.identity_files */
 788         load_public_identity_files();
 789
 790         /* Expand ~ in known host file names. */
 791         /* XXX mem-leaks: */
 792         options.system_hostfile =
 793             tilde_expand_filename(options.system_hostfile, original_real_uid);
 794         options.user_hostfile =
 795             tilde_expand_filename(options.user_hostfile, original_real_uid);
 796         options.system_hostfile2 =
 797             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 798         options.user_hostfile2 =
 799             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 800
 801         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 802
 803         /* Log into the remote system.  Never returns if the login fails. */
 804         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 805             pw, timeout_ms);
 806
 807         /* We no longer need the private host keys.  Clear them now. */
 808         if (sensitive_data.nkeys != 0) {
 809                 for (i = 0; i < sensitive_data.nkeys; i++) {
 810                         if (sensitive_data.keys[i] != NULL) {
 811                                 /* Destroys contents safely */
 812                                 debug3("clear hostkey %d", i);
 813                                 key_free(sensitive_data.keys[i]);
 814                                 sensitive_data.keys[i] = NULL;
 815                         }
 816                 }
 817                 xfree(sensitive_data.keys);
 818         }
 819         for (i = 0; i < options.num_identity_files; i++) {
 820                 if (options.identity_files[i]) {
 821                         xfree(options.identity_files[i]);
 822                         options.identity_files[i] = NULL;
 823                 }
 824                 if (options.identity_keys[i]) {
 825                         key_free(options.identity_keys[i]);
 826                         options.identity_keys[i] = NULL;
 827                 }
 828         }
 829
 830         exit_status = compat20 ? ssh_session2() : ssh_session();
 831         packet_close();
 832
 833         if (options.control_path != NULL && muxserver_sock != -1)
 834                 unlink(options.control_path);
 835
 836         /*
 837          * Send SIGHUP to proxy command if used. We don't wait() in
 838          * case it hangs and instead rely on init to reap the child
 839          */
 840         if (proxy_command_pid > 1)
 841                 kill(proxy_command_pid, SIGHUP);
 842
 843         return exit_status;
 844 }
 845
 846 /* Callback for remote forward global requests */
 847 static void
 848 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 849 {
 850         Forward *rfwd = (Forward *)ctxt;
 851
 852         debug("remote forward %s for: listen %d, connect %s:%d",
 853             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
 854             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
 855         if (type == SSH2_MSG_REQUEST_FAILURE) {
 856                 if (options.exit_on_forward_failure)
 857                         fatal("Error: remote port forwarding failed for "
 858                             "listen port %d", rfwd->listen_port);
 859                 else
 860                         logit("Warning: remote port forwarding failed for "
 861                             "listen port %d", rfwd->listen_port);
 862         }
 863         if (++remote_forward_confirms_received == options.num_remote_forwards) {
 864                 debug("All remote forwarding requests processed");
 865                 if (fork_after_authentication_flag) {
 866                         fork_after_authentication_flag = 0;
 867                         if (daemon(1, 1) < 0)
 868                                 fatal("daemon() failed: %.200s",
 869                                     strerror(errno));
 870                 }
 871         }
 872 }
 873
 874 static void
 875 ssh_init_forwarding(void)
 876 {
 877         int success = 0;
 878         int i;
 879
 880         /* Initiate local TCP/IP port forwardings. */
 881         for (i = 0; i < options.num_local_forwards; i++) {
 882                 debug("Local connections to %.200s:%d forwarded to remote "
 883                     "address %.200s:%d",
 884                     (options.local_forwards[i].listen_host == NULL) ?
 885                     (options.gateway_ports ? "*" : "LOCALHOST") :
 886                     options.local_forwards[i].listen_host,
 887                     options.local_forwards[i].listen_port,
 888                     options.local_forwards[i].connect_host,
 889                     options.local_forwards[i].connect_port);
 890                 success += channel_setup_local_fwd_listener(
 891                     options.local_forwards[i].listen_host,
 892                     options.local_forwards[i].listen_port,
 893                     options.local_forwards[i].connect_host,
 894                     options.local_forwards[i].connect_port,
 895                     options.gateway_ports);
 896         }
 897         if (i > 0 && success != i && options.exit_on_forward_failure)
 898                 fatal("Could not request local forwarding.");
 899         if (i > 0 && success == 0)
 900                 error("Could not request local forwarding.");
 901
 902         /* Initiate remote TCP/IP port forwardings. */
 903         for (i = 0; i < options.num_remote_forwards; i++) {
 904                 debug("Remote connections from %.200s:%d forwarded to "
 905                     "local address %.200s:%d",
 906                     (options.remote_forwards[i].listen_host == NULL) ?
 907                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 908                     options.remote_forwards[i].listen_port,
 909                     options.remote_forwards[i].connect_host,
 910                     options.remote_forwards[i].connect_port);
 911                 if (channel_request_remote_forwarding(
 912                     options.remote_forwards[i].listen_host,
 913                     options.remote_forwards[i].listen_port,
 914                     options.remote_forwards[i].connect_host,
 915                     options.remote_forwards[i].connect_port) < 0) {
 916                         if (options.exit_on_forward_failure)
 917                                 fatal("Could not request remote forwarding.");
 918                         else
 919                                 logit("Warning: Could not request remote "
 920                                     "forwarding.");
 921                 }
 922                 client_register_global_confirm(ssh_confirm_remote_forward,
 923                     &options.remote_forwards[i]);
 924         }
 925
 926         /* Initiate tunnel forwarding. */
 927         if (options.tun_open != SSH_TUNMODE_NO) {
 928                 if (client_request_tun_fwd(options.tun_open,
 929                     options.tun_local, options.tun_remote) == -1) {
 930                         if (options.exit_on_forward_failure)
 931                                 fatal("Could not request tunnel forwarding.");
 932                         else
 933                                 error("Could not request tunnel forwarding.");
 934                 }
 935         }
 936 }
 937
 938 static void
 939 check_agent_present(void)
 940 {
 941         if (options.forward_agent) {
 942                 /* Clear agent forwarding if we don't have an agent. */
 943                 if (!ssh_agent_present())
 944                         options.forward_agent = 0;
 945         }
 946 }
 947
 948 static int
 949 ssh_session(void)
 950 {
 951         int type;
 952         int interactive = 0;
 953         int have_tty = 0;
 954         struct winsize ws;
 955         char *cp;
 956         const char *display;
 957
 958         /* Enable compression if requested. */
 959         if (options.compression) {
 960                 debug("Requesting compression at level %d.",
 961                     options.compression_level);
 962
 963                 if (options.compression_level < 1 ||
 964                     options.compression_level > 9)
 965                         fatal("Compression level must be from 1 (fast) to "
 966                             "9 (slow, best).");
 967
 968                 /* Send the request. */
 969                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 970                 packet_put_int(options.compression_level);
 971                 packet_send();
 972                 packet_write_wait();
 973                 type = packet_read();
 974                 if (type == SSH_SMSG_SUCCESS)
 975                         packet_start_compression(options.compression_level);
 976                 else if (type == SSH_SMSG_FAILURE)
 977                         logit("Warning: Remote host refused compression.");
 978                 else
 979                         packet_disconnect("Protocol error waiting for "
 980                             "compression response.");
 981         }
 982         /* Allocate a pseudo tty if appropriate. */
 983         if (tty_flag) {
 984                 debug("Requesting pty.");
 985
 986                 /* Start the packet. */
 987                 packet_start(SSH_CMSG_REQUEST_PTY);
 988
 989                 /* Store TERM in the packet.  There is no limit on the
 990                    length of the string. */
 991                 cp = getenv("TERM");
 992                 if (!cp)
 993                         cp = "";
 994                 packet_put_cstring(cp);
 995
 996                 /* Store window size in the packet. */
 997                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 998                         memset(&ws, 0, sizeof(ws));
 999                 packet_put_int((u_int)ws.ws_row);
1000                 packet_put_int((u_int)ws.ws_col);
1001                 packet_put_int((u_int)ws.ws_xpixel);
1002                 packet_put_int((u_int)ws.ws_ypixel);
1003
1004                 /* Store tty modes in the packet. */
1005                 tty_make_modes(fileno(stdin), NULL);
1006
1007                 /* Send the packet, and wait for it to leave. */
1008                 packet_send();
1009                 packet_write_wait();
1010
1011                 /* Read response from the server. */
1012                 type = packet_read();
1013                 if (type == SSH_SMSG_SUCCESS) {
1014                         interactive = 1;
1015                         have_tty = 1;
1016                 } else if (type == SSH_SMSG_FAILURE)
1017                         logit("Warning: Remote host failed or refused to "
1018                             "allocate a pseudo tty.");
1019                 else
1020                         packet_disconnect("Protocol error waiting for pty "
1021                             "request response.");
1022         }
1023         /* Request X11 forwarding if enabled and DISPLAY is set. */
1024         display = getenv("DISPLAY");
1025         if (options.forward_x11 && display != NULL) {
1026                 char *proto, *data;
1027                 /* Get reasonable local authentication information. */
1028                 client_x11_get_proto(display, options.xauth_location,
1029                     options.forward_x11_trusted, &proto, &data);
1030                 /* Request forwarding with authentication spoofing. */
1031                 debug("Requesting X11 forwarding with authentication "
1032                     "spoofing.");
1033                 x11_request_forwarding_with_spoofing(0, display, proto, data);
1034
1035                 /* Read response from the server. */
1036                 type = packet_read();
1037                 if (type == SSH_SMSG_SUCCESS) {
1038                         interactive = 1;
1039                 } else if (type == SSH_SMSG_FAILURE) {
1040                         logit("Warning: Remote host denied X11 forwarding.");
1041                 } else {
1042                         packet_disconnect("Protocol error waiting for X11 "
1043                             "forwarding");
1044                 }
1045         }
1046         /* Tell the packet module whether this is an interactive session. */
1047         packet_set_interactive(interactive);
1048
1049         /* Request authentication agent forwarding if appropriate. */
1050         check_agent_present();
1051
1052         if (options.forward_agent) {
1053                 debug("Requesting authentication agent forwarding.");
1054                 auth_request_forwarding();
1055
1056                 /* Read response from the server. */
1057                 type = packet_read();
1058                 packet_check_eom();
1059                 if (type != SSH_SMSG_SUCCESS)
1060                         logit("Warning: Remote host denied authentication agent forwarding.");
1061         }
1062
1063         /* Initiate port forwardings. */
1064         ssh_init_forwarding();
1065
1066         /* Execute a local command */
1067         if (options.local_command != NULL &&
1068             options.permit_local_command)
1069                 ssh_local_cmd(options.local_command);
1070
1071         /*
1072          * If requested and we are not interested in replies to remote
1073          * forwarding requests, then let ssh continue in the background.
1074          */
1075         if (fork_after_authentication_flag &&
1076             (!options.exit_on_forward_failure ||
1077             options.num_remote_forwards == 0)) {
1078                 fork_after_authentication_flag = 0;
1079                 if (daemon(1, 1) < 0)
1080                         fatal("daemon() failed: %.200s", strerror(errno));
1081         }
1082
1083         /*
1084          * If a command was specified on the command line, execute the
1085          * command now. Otherwise request the server to start a shell.
1086          */
1087         if (buffer_len(&command) > 0) {
1088                 int len = buffer_len(&command);
1089                 if (len > 900)
1090                         len = 900;
1091                 debug("Sending command: %.*s", len,
1092                     (u_char *)buffer_ptr(&command));
1093                 packet_start(SSH_CMSG_EXEC_CMD);
1094                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1095                 packet_send();
1096                 packet_write_wait();
1097         } else {
1098                 debug("Requesting shell.");
1099                 packet_start(SSH_CMSG_EXEC_SHELL);
1100                 packet_send();
1101                 packet_write_wait();
1102         }
1103
1104         /* Enter the interactive session. */
1105         return client_loop(have_tty, tty_flag ?
1106             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1107 }
1108
1109 /* request pty/x11/agent/tcpfwd/shell for channel */
1110 static void
1111 ssh_session2_setup(int id, void *arg)
1112 {
1113         extern char **environ;
1114         const char *display;
1115         int interactive = tty_flag;
1116
1117         display = getenv("DISPLAY");
1118         if (options.forward_x11 && display != NULL) {
1119                 char *proto, *data;
1120                 /* Get reasonable local authentication information. */
1121                 client_x11_get_proto(display, options.xauth_location,
1122                     options.forward_x11_trusted, &proto, &data);
1123                 /* Request forwarding with authentication spoofing. */
1124                 debug("Requesting X11 forwarding with authentication "
1125                     "spoofing.");
1126                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1127                 interactive = 1;
1128                 /* XXX wait for reply */
1129         }
1130
1131         check_agent_present();
1132         if (options.forward_agent) {
1133                 debug("Requesting authentication agent forwarding.");
1134                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1135                 packet_send();
1136         }
1137
1138         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1139             NULL, fileno(stdin), &command, environ);
1140
1141         packet_set_interactive(interactive);
1142 }
1143
1144 /* open new channel for a session */
1145 static int
1146 ssh_session2_open(void)
1147 {
1148         Channel *c;
1149         int window, packetmax, in, out, err;
1150
1151         if (stdin_null_flag) {
1152                 in = open(_PATH_DEVNULL, O_RDONLY);
1153         } else {
1154                 in = dup(STDIN_FILENO);
1155         }
1156         out = dup(STDOUT_FILENO);
1157         err = dup(STDERR_FILENO);
1158
1159         if (in < 0 || out < 0 || err < 0)
1160                 fatal("dup() in/out/err failed");
1161
1162         /* enable nonblocking unless tty */
1163         if (!isatty(in))
1164                 set_nonblock(in);
1165         if (!isatty(out))
1166                 set_nonblock(out);
1167         if (!isatty(err))
1168                 set_nonblock(err);
1169
1170         window = CHAN_SES_WINDOW_DEFAULT;
1171         packetmax = CHAN_SES_PACKET_DEFAULT;
1172         if (tty_flag) {
1173                 window >>= 1;
1174                 packetmax >>= 1;
1175         }
1176         c = channel_new(
1177             "session", SSH_CHANNEL_OPENING, in, out, err,
1178             window, packetmax, CHAN_EXTENDED_WRITE,
1179             "client-session", /*nonblock*/0);
1180
1181         debug3("ssh_session2_open: channel_new: %d", c->self);
1182
1183         channel_send_open(c->self);
1184         if (!no_shell_flag)
1185                 channel_register_open_confirm(c->self,
1186                     ssh_session2_setup, NULL);
1187
1188         return c->self;
1189 }
1190
1191 static int
1192 ssh_session2(void)
1193 {
1194         int id = -1;
1195
1196         /* XXX should be pre-session */
1197         ssh_init_forwarding();
1198
1199         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1200                 id = ssh_session2_open();
1201
1202         /* If we don't expect to open a new session, then disallow it */
1203         if (options.control_master == SSHCTL_MASTER_NO) {
1204                 debug("Requesting no-more-sessions@openssh.com");
1205                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1206                 packet_put_cstring("no-more-sessions@openssh.com");
1207                 packet_put_char(0);
1208                 packet_send();
1209         }
1210
1211         /* Execute a local command */
1212         if (options.local_command != NULL &&
1213             options.permit_local_command)
1214                 ssh_local_cmd(options.local_command);
1215
1216         /* Start listening for multiplex clients */
1217         muxserver_listen();
1218
1219         /* If requested, let ssh continue in the background. */
1220         if (fork_after_authentication_flag) {
1221                 fork_after_authentication_flag = 0;
1222                 if (daemon(1, 1) < 0)
1223                         fatal("daemon() failed: %.200s", strerror(errno));
1224         }
1225
1226         return client_loop(tty_flag, tty_flag ?
1227             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1228 }
1229
1230 static void
1231 load_public_identity_files(void)
1232 {
1233         char *filename, *cp, thishost[NI_MAXHOST];
1234         char *pwdir = NULL, *pwname = NULL;
1235         int i = 0;
1236         Key *public;
1237         struct passwd *pw;
1238 #ifdef SMARTCARD
1239         Key **keys;
1240
1241         if (options.smartcard_device != NULL &&
1242             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1243             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL) {
1244                 int count = 0;
1245                 for (i = 0; keys[i] != NULL; i++) {
1246                         count++;
1247                         memmove(&options.identity_files[1],
1248                             &options.identity_files[0],
1249                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1250                         memmove(&options.identity_keys[1],
1251                             &options.identity_keys[0],
1252                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1253                         options.num_identity_files++;
1254                         options.identity_keys[0] = keys[i];
1255                         options.identity_files[0] = sc_get_key_label(keys[i]);
1256                 }
1257                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1258                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1259                 i = count;
1260                 xfree(keys);
1261         }
1262 #endif /* SMARTCARD */
1263         if ((pw = getpwuid(original_real_uid)) == NULL)
1264                 fatal("load_public_identity_files: getpwuid failed");
1265         pwname = xstrdup(pw->pw_name);
1266         pwdir = xstrdup(pw->pw_dir);
1267         if (gethostname(thishost, sizeof(thishost)) == -1)
1268                 fatal("load_public_identity_files: gethostname: %s",
1269                     strerror(errno));
1270         for (; i < options.num_identity_files; i++) {
1271                 cp = tilde_expand_filename(options.identity_files[i],
1272                     original_real_uid);
1273                 filename = percent_expand(cp, "d", pwdir,
1274                     "u", pwname, "l", thishost, "h", host,
1275                     "r", options.user, (char *)NULL);
1276                 xfree(cp);
1277                 public = key_load_public(filename, NULL);
1278                 debug("identity file %s type %d", filename,
1279                     public ? public->type : -1);
1280                 xfree(options.identity_files[i]);
1281                 options.identity_files[i] = filename;
1282                 options.identity_keys[i] = public;
1283         }
1284         bzero(pwname, strlen(pwname));
1285         xfree(pwname);
1286         bzero(pwdir, strlen(pwdir));
1287         xfree(pwdir);
1288 }