ssh.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * Ssh client program.  This program can be used to log into a remote machine.
   6  * The software supports strong authentication, encryption, and forwarding
   7  * of X11, TCP/IP, and authentication connections.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  16  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  17  *
  18  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  19  * in Canada (German citizen).
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43 RCSID("$OpenBSD: ssh.c,v 1.213 2004/05/08 00:01:37 deraadt Exp $");
  44
  45 #include <openssl/evp.h>
  46 #include <openssl/err.h>
  47
  48 #include "ssh.h"
  49 #include "ssh1.h"
  50 #include "ssh2.h"
  51 #include "compat.h"
  52 #include "cipher.h"
  53 #include "xmalloc.h"
  54 #include "packet.h"
  55 #include "buffer.h"
  56 #include "channels.h"
  57 #include "key.h"
  58 #include "authfd.h"
  59 #include "authfile.h"
  60 #include "pathnames.h"
  61 #include "clientloop.h"
  62 #include "log.h"
  63 #include "readconf.h"
  64 #include "sshconnect.h"
  65 #include "dispatch.h"
  66 #include "misc.h"
  67 #include "kex.h"
  68 #include "mac.h"
  69 #include "sshpty.h"
  70 #include "match.h"
  71
  72 #ifdef SMARTCARD
  73 #include "scard.h"
  74 #endif
  75
  76 #ifdef HAVE___PROGNAME
  77 extern char *__progname;
  78 #else
  79 char *__progname;
  80 #endif
  81
  82 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
  83 int debug_flag = 0;
  84
  85 /* Flag indicating whether a tty should be allocated */
  86 int tty_flag = 0;
  87 int no_tty_flag = 0;
  88 int force_tty_flag = 0;
  89
  90 /* don't exec a shell */
  91 int no_shell_flag = 0;
  92
  93 /*
  94  * Flag indicating that nothing should be read from stdin.  This can be set
  95  * on the command line.
  96  */
  97 int stdin_null_flag = 0;
  98
  99 /*
 100  * Flag indicating that ssh should fork after authentication.  This is useful
 101  * so that the passphrase can be entered manually, and then ssh goes to the
 102  * background.
 103  */
 104 int fork_after_authentication_flag = 0;
 105
 106 /*
 107  * General data structure for command line options and options configurable
 108  * in configuration files.  See readconf.h.
 109  */
 110 Options options;
 111
 112 /* optional user configfile */
 113 char *config = NULL;
 114
 115 /*
 116  * Name of the host we are connecting to.  This is the name given on the
 117  * command line, or the HostName specified for the user-supplied name in a
 118  * configuration file.
 119  */
 120 char *host;
 121
 122 /* socket address the host resolves to */
 123 struct sockaddr_storage hostaddr;
 124
 125 /* Private host keys. */
 126 Sensitive sensitive_data;
 127
 128 /* Original real UID. */
 129 uid_t original_real_uid;
 130 uid_t original_effective_uid;
 131
 132 /* command to be executed */
 133 Buffer command;
 134
 135 /* Should we execute a command or invoke a subsystem? */
 136 int subsystem_flag = 0;
 137
 138 /* # of replies received for global requests */
 139 static int client_global_request_id = 0;
 140
 141 /* pid of proxycommand child process */
 142 pid_t proxy_command_pid = 0;
 143
 144 /* Prints a help message to the user.  This function never returns. */
 145
 146 static void
 147 usage(void)
 148 {
 149         fprintf(stderr,
 150 "usage: ssh [-1246AaCfghkNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 151 "           [-D port] [-e escape_char] [-F configfile] [-i identity_file]\n"
 152 "           [-L port:host:hostport] [-l login_name] [-m mac_spec] [-o option]\n"
 153 "           [-p port] [-R port:host:hostport] [user@]hostname [command]\n"
 154         );
 155         exit(1);
 156 }
 157
 158 static int ssh_session(void);
 159 static int ssh_session2(void);
 160 static void load_public_identity_files(void);
 161
 162 /*
 163  * Main program for the ssh client.
 164  */
 165 int
 166 main(int ac, char **av)
 167 {
 168         int i, opt, exit_status;
 169         u_short fwd_port, fwd_host_port;
 170         char sfwd_port[6], sfwd_host_port[6];
 171         char *p, *cp, *line, buf[256];
 172         struct stat st;
 173         struct passwd *pw;
 174         int dummy;
 175         extern int optind, optreset;
 176         extern char *optarg;
 177
 178         __progname = ssh_get_progname(av[0]);
 179         init_rng();
 180
 181         /*
 182          * Save the original real uid.  It will be needed later (uid-swapping
 183          * may clobber the real uid).
 184          */
 185         original_real_uid = getuid();
 186         original_effective_uid = geteuid();
 187
 188         /*
 189          * Use uid-swapping to give up root privileges for the duration of
 190          * option processing.  We will re-instantiate the rights when we are
 191          * ready to create the privileged port, and will permanently drop
 192          * them when the port has been created (actually, when the connection
 193          * has been made, as we may need to create the port several times).
 194          */
 195         PRIV_END;
 196
 197 #ifdef HAVE_SETRLIMIT
 198         /* If we are installed setuid root be careful to not drop core. */
 199         if (original_real_uid != original_effective_uid) {
 200                 struct rlimit rlim;
 201                 rlim.rlim_cur = rlim.rlim_max = 0;
 202                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 203                         fatal("setrlimit failed: %.100s", strerror(errno));
 204         }
 205 #endif
 206         /* Get user data. */
 207         pw = getpwuid(original_real_uid);
 208         if (!pw) {
 209                 logit("You don't exist, go away!");
 210                 exit(1);
 211         }
 212         /* Take a copy of the returned structure. */
 213         pw = pwcopy(pw);
 214
 215         /*
 216          * Set our umask to something reasonable, as some files are created
 217          * with the default umask.  This will make them world-readable but
 218          * writable only by the owner, which is ok for all files for which we
 219          * don't set the modes explicitly.
 220          */
 221         umask(022);
 222
 223         /* Initialize option structure to indicate that no values have been set. */
 224         initialize_options(&options);
 225
 226         /* Parse command-line arguments. */
 227         host = NULL;
 228
 229 again:
 230         while ((opt = getopt(ac, av,
 231             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVXY")) != -1) {
 232                 switch (opt) {
 233                 case '1':
 234                         options.protocol = SSH_PROTO_1;
 235                         break;
 236                 case '2':
 237                         options.protocol = SSH_PROTO_2;
 238                         break;
 239                 case '4':
 240                         options.address_family = AF_INET;
 241                         break;
 242                 case '6':
 243                         options.address_family = AF_INET6;
 244                         break;
 245                 case 'n':
 246                         stdin_null_flag = 1;
 247                         break;
 248                 case 'f':
 249                         fork_after_authentication_flag = 1;
 250                         stdin_null_flag = 1;
 251                         break;
 252                 case 'x':
 253                         options.forward_x11 = 0;
 254                         break;
 255                 case 'X':
 256                         options.forward_x11 = 1;
 257                         break;
 258                 case 'Y':
 259                         options.forward_x11 = 1;
 260                         options.forward_x11_trusted = 1;
 261                         break;
 262                 case 'g':
 263                         options.gateway_ports = 1;
 264                         break;
 265                 case 'P':       /* deprecated */
 266                         options.use_privileged_port = 0;
 267                         break;
 268                 case 'a':
 269                         options.forward_agent = 0;
 270                         break;
 271                 case 'A':
 272                         options.forward_agent = 1;
 273                         break;
 274                 case 'k':
 275                         options.gss_deleg_creds = 0;
 276                         break;
 277                 case 'i':
 278                         if (stat(optarg, &st) < 0) {
 279                                 fprintf(stderr, "Warning: Identity file %s "
 280                                     "does not exist.\n", optarg);
 281                                 break;
 282                         }
 283                         if (options.num_identity_files >=
 284                             SSH_MAX_IDENTITY_FILES)
 285                                 fatal("Too many identity files specified "
 286                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 287                         options.identity_files[options.num_identity_files++] =
 288                             xstrdup(optarg);
 289                         break;
 290                 case 'I':
 291 #ifdef SMARTCARD
 292                         options.smartcard_device = xstrdup(optarg);
 293 #else
 294                         fprintf(stderr, "no support for smartcards.\n");
 295 #endif
 296                         break;
 297                 case 't':
 298                         if (tty_flag)
 299                                 force_tty_flag = 1;
 300                         tty_flag = 1;
 301                         break;
 302                 case 'v':
 303                         if (debug_flag == 0) {
 304                                 debug_flag = 1;
 305                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 306                         } else {
 307                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 308                                         options.log_level++;
 309                                 break;
 310                         }
 311                         /* fallthrough */
 312                 case 'V':
 313                         fprintf(stderr, "%s, %s\n",
 314                             SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
 315                         if (opt == 'V')
 316                                 exit(0);
 317                         break;
 318                 case 'q':
 319                         options.log_level = SYSLOG_LEVEL_QUIET;
 320                         break;
 321                 case 'e':
 322                         if (optarg[0] == '^' && optarg[2] == 0 &&
 323                             (u_char) optarg[1] >= 64 &&
 324                             (u_char) optarg[1] < 128)
 325                                 options.escape_char = (u_char) optarg[1] & 31;
 326                         else if (strlen(optarg) == 1)
 327                                 options.escape_char = (u_char) optarg[0];
 328                         else if (strcmp(optarg, "none") == 0)
 329                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 330                         else {
 331                                 fprintf(stderr, "Bad escape character '%s'.\n",
 332                                     optarg);
 333                                 exit(1);
 334                         }
 335                         break;
 336                 case 'c':
 337                         if (ciphers_valid(optarg)) {
 338                                 /* SSH2 only */
 339                                 options.ciphers = xstrdup(optarg);
 340                                 options.cipher = SSH_CIPHER_ILLEGAL;
 341                         } else {
 342                                 /* SSH1 only */
 343                                 options.cipher = cipher_number(optarg);
 344                                 if (options.cipher == -1) {
 345                                         fprintf(stderr,
 346                                             "Unknown cipher type '%s'\n",
 347                                             optarg);
 348                                         exit(1);
 349                                 }
 350                                 if (options.cipher == SSH_CIPHER_3DES)
 351                                         options.ciphers = "3des-cbc";
 352                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 353                                         options.ciphers = "blowfish-cbc";
 354                                 else
 355                                         options.ciphers = (char *)-1;
 356                         }
 357                         break;
 358                 case 'm':
 359                         if (mac_valid(optarg))
 360                                 options.macs = xstrdup(optarg);
 361                         else {
 362                                 fprintf(stderr, "Unknown mac type '%s'\n",
 363                                     optarg);
 364                                 exit(1);
 365                         }
 366                         break;
 367                 case 'p':
 368                         options.port = a2port(optarg);
 369                         if (options.port == 0) {
 370                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 371                                 exit(1);
 372                         }
 373                         break;
 374                 case 'l':
 375                         options.user = optarg;
 376                         break;
 377
 378                 case 'L':
 379                 case 'R':
 380                         if (sscanf(optarg, "%5[0123456789]:%255[^:]:%5[0123456789]",
 381                             sfwd_port, buf, sfwd_host_port) != 3 &&
 382                             sscanf(optarg, "%5[0123456789]/%255[^/]/%5[0123456789]",
 383                             sfwd_port, buf, sfwd_host_port) != 3) {
 384                                 fprintf(stderr,
 385                                     "Bad forwarding specification '%s'\n",
 386                                     optarg);
 387                                 usage();
 388                                 /* NOTREACHED */
 389                         }
 390                         if ((fwd_port = a2port(sfwd_port)) == 0 ||
 391                             (fwd_host_port = a2port(sfwd_host_port)) == 0) {
 392                                 fprintf(stderr,
 393                                     "Bad forwarding port(s) '%s'\n", optarg);
 394                                 exit(1);
 395                         }
 396                         if (opt == 'L')
 397                                 add_local_forward(&options, fwd_port, buf,
 398                                     fwd_host_port);
 399                         else if (opt == 'R')
 400                                 add_remote_forward(&options, fwd_port, buf,
 401                                     fwd_host_port);
 402                         break;
 403
 404                 case 'D':
 405                         fwd_port = a2port(optarg);
 406                         if (fwd_port == 0) {
 407                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 408                                     optarg);
 409                                 exit(1);
 410                         }
 411                         add_local_forward(&options, fwd_port, "socks", 0);
 412                         break;
 413
 414                 case 'C':
 415                         options.compression = 1;
 416                         break;
 417                 case 'N':
 418                         no_shell_flag = 1;
 419                         no_tty_flag = 1;
 420                         break;
 421                 case 'T':
 422                         no_tty_flag = 1;
 423                         break;
 424                 case 'o':
 425                         dummy = 1;
 426                         line = xstrdup(optarg);
 427                         if (process_config_line(&options, host ? host : "",
 428                             line, "command-line", 0, &dummy) != 0)
 429                                 exit(1);
 430                         xfree(line);
 431                         break;
 432                 case 's':
 433                         subsystem_flag = 1;
 434                         break;
 435                 case 'b':
 436                         options.bind_address = optarg;
 437                         break;
 438                 case 'F':
 439                         config = optarg;
 440                         break;
 441                 default:
 442                         usage();
 443                 }
 444         }
 445
 446         ac -= optind;
 447         av += optind;
 448
 449         if (ac > 0 && !host && **av != '-') {
 450                 if (strrchr(*av, '@')) {
 451                         p = xstrdup(*av);
 452                         cp = strrchr(p, '@');
 453                         if (cp == NULL || cp == p)
 454                                 usage();
 455                         options.user = p;
 456                         *cp = '\0';
 457                         host = ++cp;
 458                 } else
 459                         host = *av;
 460                 if (ac > 1) {
 461                         optind = optreset = 1;
 462                         goto again;
 463                 }
 464                 ac--, av++;
 465         }
 466
 467         /* Check that we got a host name. */
 468         if (!host)
 469                 usage();
 470
 471         SSLeay_add_all_algorithms();
 472         ERR_load_crypto_strings();
 473
 474         /* Initialize the command to execute on remote host. */
 475         buffer_init(&command);
 476
 477         /*
 478          * Save the command to execute on the remote host in a buffer. There
 479          * is no limit on the length of the command, except by the maximum
 480          * packet size.  Also sets the tty flag if there is no command.
 481          */
 482         if (!ac) {
 483                 /* No command specified - execute shell on a tty. */
 484                 tty_flag = 1;
 485                 if (subsystem_flag) {
 486                         fprintf(stderr,
 487                             "You must specify a subsystem to invoke.\n");
 488                         usage();
 489                 }
 490         } else {
 491                 /* A command has been specified.  Store it into the buffer. */
 492                 for (i = 0; i < ac; i++) {
 493                         if (i)
 494                                 buffer_append(&command, " ", 1);
 495                         buffer_append(&command, av[i], strlen(av[i]));
 496                 }
 497         }
 498
 499         /* Cannot fork to background if no command. */
 500         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 501                 fatal("Cannot fork into background without a command to execute.");
 502
 503         /* Allocate a tty by default if no command specified. */
 504         if (buffer_len(&command) == 0)
 505                 tty_flag = 1;
 506
 507         /* Force no tty */
 508         if (no_tty_flag)
 509                 tty_flag = 0;
 510         /* Do not allocate a tty if stdin is not a tty. */
 511         if (!isatty(fileno(stdin)) && !force_tty_flag) {
 512                 if (tty_flag)
 513                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 514                 tty_flag = 0;
 515         }
 516
 517         /*
 518          * Initialize "log" output.  Since we are the client all output
 519          * actually goes to stderr.
 520          */
 521         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 522             SYSLOG_FACILITY_USER, 1);
 523
 524         /*
 525          * Read per-user configuration file.  Ignore the system wide config
 526          * file if the user specifies a config file on the command line.
 527          */
 528         if (config != NULL) {
 529                 if (!read_config_file(config, host, &options, 0))
 530                         fatal("Can't open user config file %.100s: "
 531                             "%.100s", config, strerror(errno));
 532         } else  {
 533                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 534                     _PATH_SSH_USER_CONFFILE);
 535                 (void)read_config_file(buf, host, &options, 1);
 536
 537                 /* Read systemwide configuration file after use config. */
 538                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 539                     &options, 0);
 540         }
 541
 542         /* Fill configuration defaults. */
 543         fill_default_options(&options);
 544
 545         channel_set_af(options.address_family);
 546
 547         /* reinit */
 548         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 549
 550         seed_rng();
 551
 552         if (options.user == NULL)
 553                 options.user = xstrdup(pw->pw_name);
 554
 555         if (options.hostname != NULL)
 556                 host = options.hostname;
 557
 558         /* force lowercase for hostkey matching */
 559         if (options.host_key_alias != NULL) {
 560                 for (p = options.host_key_alias; *p; p++)
 561                         if (isupper(*p))
 562                                 *p = tolower(*p);
 563         }
 564
 565         if (options.proxy_command != NULL &&
 566             strcmp(options.proxy_command, "none") == 0)
 567                 options.proxy_command = NULL;
 568
 569         /* Open a connection to the remote host. */
 570         if (ssh_connect(host, &hostaddr, options.port,
 571             options.address_family, options.connection_attempts,
 572 #ifdef HAVE_CYGWIN
 573             options.use_privileged_port,
 574 #else
 575             original_effective_uid == 0 && options.use_privileged_port,
 576 #endif
 577             options.proxy_command) != 0)
 578                 exit(1);
 579
 580         /*
 581          * If we successfully made the connection, load the host private key
 582          * in case we will need it later for combined rsa-rhosts
 583          * authentication. This must be done before releasing extra
 584          * privileges, because the file is only readable by root.
 585          * If we cannot access the private keys, load the public keys
 586          * instead and try to execute the ssh-keysign helper instead.
 587          */
 588         sensitive_data.nkeys = 0;
 589         sensitive_data.keys = NULL;
 590         sensitive_data.external_keysign = 0;
 591         if (options.rhosts_rsa_authentication ||
 592             options.hostbased_authentication) {
 593                 sensitive_data.nkeys = 3;
 594                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 595                     sizeof(Key));
 596
 597                 PRIV_START;
 598                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 599                     _PATH_HOST_KEY_FILE, "", NULL);
 600                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 601                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 602                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 603                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 604                 PRIV_END;
 605
 606                 if (options.hostbased_authentication == 1 &&
 607                     sensitive_data.keys[0] == NULL &&
 608                     sensitive_data.keys[1] == NULL &&
 609                     sensitive_data.keys[2] == NULL) {
 610                         sensitive_data.keys[1] = key_load_public(
 611                             _PATH_HOST_DSA_KEY_FILE, NULL);
 612                         sensitive_data.keys[2] = key_load_public(
 613                             _PATH_HOST_RSA_KEY_FILE, NULL);
 614                         sensitive_data.external_keysign = 1;
 615                 }
 616         }
 617         /*
 618          * Get rid of any extra privileges that we may have.  We will no
 619          * longer need them.  Also, extra privileges could make it very hard
 620          * to read identity files and other non-world-readable files from the
 621          * user's home directory if it happens to be on a NFS volume where
 622          * root is mapped to nobody.
 623          */
 624         seteuid(original_real_uid);
 625         setuid(original_real_uid);
 626
 627         /*
 628          * Now that we are back to our own permissions, create ~/.ssh
 629          * directory if it doesn\'t already exist.
 630          */
 631         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 632         if (stat(buf, &st) < 0)
 633                 if (mkdir(buf, 0700) < 0)
 634                         error("Could not create directory '%.200s'.", buf);
 635
 636         /* load options.identity_files */
 637         load_public_identity_files();
 638
 639         /* Expand ~ in known host file names. */
 640         /* XXX mem-leaks: */
 641         options.system_hostfile =
 642             tilde_expand_filename(options.system_hostfile, original_real_uid);
 643         options.user_hostfile =
 644             tilde_expand_filename(options.user_hostfile, original_real_uid);
 645         options.system_hostfile2 =
 646             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 647         options.user_hostfile2 =
 648             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 649
 650         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 651
 652         /* Log into the remote system.  This never returns if the login fails. */
 653         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 654
 655         /* We no longer need the private host keys.  Clear them now. */
 656         if (sensitive_data.nkeys != 0) {
 657                 for (i = 0; i < sensitive_data.nkeys; i++) {
 658                         if (sensitive_data.keys[i] != NULL) {
 659                                 /* Destroys contents safely */
 660                                 debug3("clear hostkey %d", i);
 661                                 key_free(sensitive_data.keys[i]);
 662                                 sensitive_data.keys[i] = NULL;
 663                         }
 664                 }
 665                 xfree(sensitive_data.keys);
 666         }
 667         for (i = 0; i < options.num_identity_files; i++) {
 668                 if (options.identity_files[i]) {
 669                         xfree(options.identity_files[i]);
 670                         options.identity_files[i] = NULL;
 671                 }
 672                 if (options.identity_keys[i]) {
 673                         key_free(options.identity_keys[i]);
 674                         options.identity_keys[i] = NULL;
 675                 }
 676         }
 677
 678         exit_status = compat20 ? ssh_session2() : ssh_session();
 679         packet_close();
 680
 681         /*
 682          * Send SIGHUP to proxy command if used. We don't wait() in
 683          * case it hangs and instead rely on init to reap the child
 684          */
 685         if (proxy_command_pid > 1)
 686                 kill(proxy_command_pid, SIGHUP);
 687
 688         return exit_status;
 689 }
 690
 691 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
 692
 693 static void
 694 x11_get_proto(char **_proto, char **_data)
 695 {
 696         char cmd[1024];
 697         char line[512];
 698         char xdisplay[512];
 699         static char proto[512], data[512];
 700         FILE *f;
 701         int got_data = 0, generated = 0, do_unlink = 0, i;
 702         char *display, *xauthdir, *xauthfile;
 703         struct stat st;
 704
 705         xauthdir = xauthfile = NULL;
 706         *_proto = proto;
 707         *_data = data;
 708         proto[0] = data[0] = '\0';
 709
 710         if (!options.xauth_location ||
 711             (stat(options.xauth_location, &st) == -1)) {
 712                 debug("No xauth program.");
 713         } else {
 714                 if ((display = getenv("DISPLAY")) == NULL) {
 715                         debug("x11_get_proto: DISPLAY not set");
 716                         return;
 717                 }
 718                 /*
 719                  * Handle FamilyLocal case where $DISPLAY does
 720                  * not match an authorization entry.  For this we
 721                  * just try "xauth list unix:displaynum.screennum".
 722                  * XXX: "localhost" match to determine FamilyLocal
 723                  *      is not perfect.
 724                  */
 725                 if (strncmp(display, "localhost:", 10) == 0) {
 726                         snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
 727                             display + 10);
 728                         display = xdisplay;
 729                 }
 730                 if (options.forward_x11_trusted == 0) {
 731                         xauthdir = xmalloc(MAXPATHLEN);
 732                         xauthfile = xmalloc(MAXPATHLEN);
 733                         strlcpy(xauthdir, "/tmp/ssh-XXXXXXXXXX", MAXPATHLEN);
 734                         if (mkdtemp(xauthdir) != NULL) {
 735                                 do_unlink = 1;
 736                                 snprintf(xauthfile, MAXPATHLEN, "%s/xauthfile",
 737                                     xauthdir);
 738                                 snprintf(cmd, sizeof(cmd),
 739                                     "%s -f %s generate %s " SSH_X11_PROTO
 740                                     " untrusted timeout 1200 2>" _PATH_DEVNULL,
 741                                     options.xauth_location, xauthfile, display);
 742                                 debug2("x11_get_proto: %s", cmd);
 743                                 if (system(cmd) == 0)
 744                                         generated = 1;
 745                         }
 746                 }
 747                 snprintf(cmd, sizeof(cmd),
 748                     "%s %s%s list %s . 2>" _PATH_DEVNULL,
 749                     options.xauth_location,
 750                     generated ? "-f " : "" ,
 751                     generated ? xauthfile : "",
 752                     display);
 753                 debug2("x11_get_proto: %s", cmd);
 754                 f = popen(cmd, "r");
 755                 if (f && fgets(line, sizeof(line), f) &&
 756                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 757                         got_data = 1;
 758                 if (f)
 759                         pclose(f);
 760         }
 761
 762         if (do_unlink) {
 763                 unlink(xauthfile);
 764                 rmdir(xauthdir);
 765         }
 766         if (xauthdir)
 767                 xfree(xauthdir);
 768         if (xauthfile)
 769                 xfree(xauthfile);
 770
 771         /*
 772          * If we didn't get authentication data, just make up some
 773          * data.  The forwarding code will check the validity of the
 774          * response anyway, and substitute this data.  The X11
 775          * server, however, will ignore this fake data and use
 776          * whatever authentication mechanisms it was using otherwise
 777          * for the local connection.
 778          */
 779         if (!got_data) {
 780                 u_int32_t rand = 0;
 781
 782                 logit("Warning: No xauth data; "
 783                     "using fake authentication data for X11 forwarding.");
 784                 strlcpy(proto, SSH_X11_PROTO, sizeof proto);
 785                 for (i = 0; i < 16; i++) {
 786                         if (i % 4 == 0)
 787                                 rand = arc4random();
 788                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
 789                             rand & 0xff);
 790                         rand >>= 8;
 791                 }
 792         }
 793 }
 794
 795 static void
 796 ssh_init_forwarding(void)
 797 {
 798         int success = 0;
 799         int i;
 800
 801         /* Initiate local TCP/IP port forwardings. */
 802         for (i = 0; i < options.num_local_forwards; i++) {
 803                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
 804                     options.local_forwards[i].port,
 805                     options.local_forwards[i].host,
 806                     options.local_forwards[i].host_port);
 807                 success += channel_setup_local_fwd_listener(
 808                     options.local_forwards[i].port,
 809                     options.local_forwards[i].host,
 810                     options.local_forwards[i].host_port,
 811                     options.gateway_ports);
 812         }
 813         if (i > 0 && success == 0)
 814                 error("Could not request local forwarding.");
 815
 816         /* Initiate remote TCP/IP port forwardings. */
 817         for (i = 0; i < options.num_remote_forwards; i++) {
 818                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
 819                     options.remote_forwards[i].port,
 820                     options.remote_forwards[i].host,
 821                     options.remote_forwards[i].host_port);
 822                 channel_request_remote_forwarding(
 823                     options.remote_forwards[i].port,
 824                     options.remote_forwards[i].host,
 825                     options.remote_forwards[i].host_port);
 826         }
 827 }
 828
 829 static void
 830 check_agent_present(void)
 831 {
 832         if (options.forward_agent) {
 833                 /* Clear agent forwarding if we don\'t have an agent. */
 834                 if (!ssh_agent_present())
 835                         options.forward_agent = 0;
 836         }
 837 }
 838
 839 static int
 840 ssh_session(void)
 841 {
 842         int type;
 843         int interactive = 0;
 844         int have_tty = 0;
 845         struct winsize ws;
 846         char *cp;
 847
 848         /* Enable compression if requested. */
 849         if (options.compression) {
 850                 debug("Requesting compression at level %d.", options.compression_level);
 851
 852                 if (options.compression_level < 1 || options.compression_level > 9)
 853                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 854
 855                 /* Send the request. */
 856                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 857                 packet_put_int(options.compression_level);
 858                 packet_send();
 859                 packet_write_wait();
 860                 type = packet_read();
 861                 if (type == SSH_SMSG_SUCCESS)
 862                         packet_start_compression(options.compression_level);
 863                 else if (type == SSH_SMSG_FAILURE)
 864                         logit("Warning: Remote host refused compression.");
 865                 else
 866                         packet_disconnect("Protocol error waiting for compression response.");
 867         }
 868         /* Allocate a pseudo tty if appropriate. */
 869         if (tty_flag) {
 870                 debug("Requesting pty.");
 871
 872                 /* Start the packet. */
 873                 packet_start(SSH_CMSG_REQUEST_PTY);
 874
 875                 /* Store TERM in the packet.  There is no limit on the
 876                    length of the string. */
 877                 cp = getenv("TERM");
 878                 if (!cp)
 879                         cp = "";
 880                 packet_put_cstring(cp);
 881
 882                 /* Store window size in the packet. */
 883                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 884                         memset(&ws, 0, sizeof(ws));
 885                 packet_put_int(ws.ws_row);
 886                 packet_put_int(ws.ws_col);
 887                 packet_put_int(ws.ws_xpixel);
 888                 packet_put_int(ws.ws_ypixel);
 889
 890                 /* Store tty modes in the packet. */
 891                 tty_make_modes(fileno(stdin), NULL);
 892
 893                 /* Send the packet, and wait for it to leave. */
 894                 packet_send();
 895                 packet_write_wait();
 896
 897                 /* Read response from the server. */
 898                 type = packet_read();
 899                 if (type == SSH_SMSG_SUCCESS) {
 900                         interactive = 1;
 901                         have_tty = 1;
 902                 } else if (type == SSH_SMSG_FAILURE)
 903                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 904                 else
 905                         packet_disconnect("Protocol error waiting for pty request response.");
 906         }
 907         /* Request X11 forwarding if enabled and DISPLAY is set. */
 908         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 909                 char *proto, *data;
 910                 /* Get reasonable local authentication information. */
 911                 x11_get_proto(&proto, &data);
 912                 /* Request forwarding with authentication spoofing. */
 913                 debug("Requesting X11 forwarding with authentication spoofing.");
 914                 x11_request_forwarding_with_spoofing(0, proto, data);
 915
 916                 /* Read response from the server. */
 917                 type = packet_read();
 918                 if (type == SSH_SMSG_SUCCESS) {
 919                         interactive = 1;
 920                 } else if (type == SSH_SMSG_FAILURE) {
 921                         logit("Warning: Remote host denied X11 forwarding.");
 922                 } else {
 923                         packet_disconnect("Protocol error waiting for X11 forwarding");
 924                 }
 925         }
 926         /* Tell the packet module whether this is an interactive session. */
 927         packet_set_interactive(interactive);
 928
 929         /* Request authentication agent forwarding if appropriate. */
 930         check_agent_present();
 931
 932         if (options.forward_agent) {
 933                 debug("Requesting authentication agent forwarding.");
 934                 auth_request_forwarding();
 935
 936                 /* Read response from the server. */
 937                 type = packet_read();
 938                 packet_check_eom();
 939                 if (type != SSH_SMSG_SUCCESS)
 940                         logit("Warning: Remote host denied authentication agent forwarding.");
 941         }
 942
 943         /* Initiate port forwardings. */
 944         ssh_init_forwarding();
 945
 946         /* If requested, let ssh continue in the background. */
 947         if (fork_after_authentication_flag)
 948                 if (daemon(1, 1) < 0)
 949                         fatal("daemon() failed: %.200s", strerror(errno));
 950
 951         /*
 952          * If a command was specified on the command line, execute the
 953          * command now. Otherwise request the server to start a shell.
 954          */
 955         if (buffer_len(&command) > 0) {
 956                 int len = buffer_len(&command);
 957                 if (len > 900)
 958                         len = 900;
 959                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 960                 packet_start(SSH_CMSG_EXEC_CMD);
 961                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 962                 packet_send();
 963                 packet_write_wait();
 964         } else {
 965                 debug("Requesting shell.");
 966                 packet_start(SSH_CMSG_EXEC_SHELL);
 967                 packet_send();
 968                 packet_write_wait();
 969         }
 970
 971         /* Enter the interactive session. */
 972         return client_loop(have_tty, tty_flag ?
 973             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
 974 }
 975
 976 static void
 977 client_subsystem_reply(int type, u_int32_t seq, void *ctxt)
 978 {
 979         int id, len;
 980
 981         id = packet_get_int();
 982         len = buffer_len(&command);
 983         if (len > 900)
 984                 len = 900;
 985         packet_check_eom();
 986         if (type == SSH2_MSG_CHANNEL_FAILURE)
 987                 fatal("Request for subsystem '%.*s' failed on channel %d",
 988                     len, (u_char *)buffer_ptr(&command), id);
 989 }
 990
 991 void
 992 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
 993 {
 994         int i;
 995
 996         i = client_global_request_id++;
 997         if (i >= options.num_remote_forwards)
 998                 return;
 999         debug("remote forward %s for: listen %d, connect %s:%d",
1000             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1001             options.remote_forwards[i].port,
1002             options.remote_forwards[i].host,
1003             options.remote_forwards[i].host_port);
1004         if (type == SSH2_MSG_REQUEST_FAILURE)
1005                 logit("Warning: remote port forwarding failed for listen port %d",
1006                     options.remote_forwards[i].port);
1007 }
1008
1009 /* request pty/x11/agent/tcpfwd/shell for channel */
1010 static void
1011 ssh_session2_setup(int id, void *arg)
1012 {
1013         int len;
1014         int interactive = 0;
1015         struct termios tio;
1016
1017         debug2("ssh_session2_setup: id %d", id);
1018
1019         if (tty_flag) {
1020                 struct winsize ws;
1021                 char *cp;
1022                 cp = getenv("TERM");
1023                 if (!cp)
1024                         cp = "";
1025                 /* Store window size in the packet. */
1026                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1027                         memset(&ws, 0, sizeof(ws));
1028
1029                 channel_request_start(id, "pty-req", 0);
1030                 packet_put_cstring(cp);
1031                 packet_put_int(ws.ws_col);
1032                 packet_put_int(ws.ws_row);
1033                 packet_put_int(ws.ws_xpixel);
1034                 packet_put_int(ws.ws_ypixel);
1035                 tio = get_saved_tio();
1036                 tty_make_modes(/*ignored*/ 0, &tio);
1037                 packet_send();
1038                 interactive = 1;
1039                 /* XXX wait for reply */
1040         }
1041         if (options.forward_x11 &&
1042             getenv("DISPLAY") != NULL) {
1043                 char *proto, *data;
1044                 /* Get reasonable local authentication information. */
1045                 x11_get_proto(&proto, &data);
1046                 /* Request forwarding with authentication spoofing. */
1047                 debug("Requesting X11 forwarding with authentication spoofing.");
1048                 x11_request_forwarding_with_spoofing(id, proto, data);
1049                 interactive = 1;
1050                 /* XXX wait for reply */
1051         }
1052
1053         check_agent_present();
1054         if (options.forward_agent) {
1055                 debug("Requesting authentication agent forwarding.");
1056                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1057                 packet_send();
1058         }
1059
1060         /* Transfer any environment variables from client to server */
1061         if (options.num_send_env != 0) {
1062                 int i, j, matched;
1063                 extern char **environ;
1064                 char *name, *val;
1065
1066                 debug("Sending environment.");
1067                 for (i = 0; environ && environ[i] != NULL; i++) {
1068                         /* Split */
1069                         name = xstrdup(environ[i]);
1070                         if ((val = strchr(name, '=')) == NULL) {
1071                                 free(name);
1072                                 continue;
1073                         }
1074                         *val++ = '\0';
1075
1076                         matched = 0;
1077                         for (j = 0; j < options.num_send_env; j++) {
1078                                 if (match_pattern(name, options.send_env[j])) {
1079                                         matched = 1;
1080                                         break;
1081                                 }
1082                         }
1083                         if (!matched) {
1084                                 debug3("Ignored env %s", name);
1085                                 free(name);
1086                                 continue;
1087                         }
1088
1089                         debug("Sending env %s = %s", name, val);
1090                         channel_request_start(id, "env", 0);
1091                         packet_put_cstring(name);
1092                         packet_put_cstring(val);
1093                         packet_send();
1094                         free(name);
1095                 }
1096         }
1097
1098         len = buffer_len(&command);
1099         if (len > 0) {
1100                 if (len > 900)
1101                         len = 900;
1102                 if (subsystem_flag) {
1103                         debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command));
1104                         channel_request_start(id, "subsystem", /*want reply*/ 1);
1105                         /* register callback for reply */
1106                         /* XXX we assume that client_loop has already been called */
1107                         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
1108                         dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1109                 } else {
1110                         debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1111                         channel_request_start(id, "exec", 0);
1112                 }
1113                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1114                 packet_send();
1115         } else {
1116                 channel_request_start(id, "shell", 0);
1117                 packet_send();
1118         }
1119
1120         packet_set_interactive(interactive);
1121 }
1122
1123 /* open new channel for a session */
1124 static int
1125 ssh_session2_open(void)
1126 {
1127         Channel *c;
1128         int window, packetmax, in, out, err;
1129
1130         if (stdin_null_flag) {
1131                 in = open(_PATH_DEVNULL, O_RDONLY);
1132         } else {
1133                 in = dup(STDIN_FILENO);
1134         }
1135         out = dup(STDOUT_FILENO);
1136         err = dup(STDERR_FILENO);
1137
1138         if (in < 0 || out < 0 || err < 0)
1139                 fatal("dup() in/out/err failed");
1140
1141         /* enable nonblocking unless tty */
1142         if (!isatty(in))
1143                 set_nonblock(in);
1144         if (!isatty(out))
1145                 set_nonblock(out);
1146         if (!isatty(err))
1147                 set_nonblock(err);
1148
1149         window = CHAN_SES_WINDOW_DEFAULT;
1150         packetmax = CHAN_SES_PACKET_DEFAULT;
1151         if (tty_flag) {
1152                 window >>= 1;
1153                 packetmax >>= 1;
1154         }
1155         c = channel_new(
1156             "session", SSH_CHANNEL_OPENING, in, out, err,
1157             window, packetmax, CHAN_EXTENDED_WRITE,
1158             "client-session", /*nonblock*/0);
1159
1160         debug3("ssh_session2_open: channel_new: %d", c->self);
1161
1162         channel_send_open(c->self);
1163         if (!no_shell_flag)
1164                 channel_register_confirm(c->self, ssh_session2_setup);
1165
1166         return c->self;
1167 }
1168
1169 static int
1170 ssh_session2(void)
1171 {
1172         int id = -1;
1173
1174         /* XXX should be pre-session */
1175         ssh_init_forwarding();
1176
1177         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1178                 id = ssh_session2_open();
1179
1180         /* If requested, let ssh continue in the background. */
1181         if (fork_after_authentication_flag)
1182                 if (daemon(1, 1) < 0)
1183                         fatal("daemon() failed: %.200s", strerror(errno));
1184
1185         return client_loop(tty_flag, tty_flag ?
1186             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1187 }
1188
1189 static void
1190 load_public_identity_files(void)
1191 {
1192         char *filename;
1193         int i = 0;
1194         Key *public;
1195 #ifdef SMARTCARD
1196         Key **keys;
1197
1198         if (options.smartcard_device != NULL &&
1199             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1200             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1201                 int count = 0;
1202                 for (i = 0; keys[i] != NULL; i++) {
1203                         count++;
1204                         memmove(&options.identity_files[1], &options.identity_files[0],
1205                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1206                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1207                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1208                         options.num_identity_files++;
1209                         options.identity_keys[0] = keys[i];
1210                         options.identity_files[0] = sc_get_key_label(keys[i]);
1211                 }
1212                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1213                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1214                 i = count;
1215                 xfree(keys);
1216         }
1217 #endif /* SMARTCARD */
1218         for (; i < options.num_identity_files; i++) {
1219                 filename = tilde_expand_filename(options.identity_files[i],
1220                     original_real_uid);
1221                 public = key_load_public(filename, NULL);
1222                 debug("identity file %s type %d", filename,
1223                     public ? public->type : -1);
1224                 xfree(options.identity_files[i]);
1225                 options.identity_files[i] = filename;
1226                 options.identity_keys[i] = public;
1227         }
1228 }