ssh.c

   1 /* $OpenBSD: ssh.c,v 1.330 2010/01/09 23:04:13 dtucker 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/param.h>
  52 #include <sys/socket.h>
  53
  54 #include <ctype.h>
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #include <netdb.h>
  58 #ifdef HAVE_PATHS_H
  59 #include <paths.h>
  60 #endif
  61 #include <pwd.h>
  62 #include <signal.h>
  63 #include <stdarg.h>
  64 #include <stddef.h>
  65 #include <stdio.h>
  66 #include <stdlib.h>
  67 #include <string.h>
  68 #include <unistd.h>
  69
  70 #include <netinet/in.h>
  71 #include <arpa/inet.h>
  72
  73 #include <openssl/evp.h>
  74 #include <openssl/err.h>
  75 #include "openbsd-compat/openssl-compat.h"
  76 #include "openbsd-compat/sys-queue.h"
  77
  78 #include "xmalloc.h"
  79 #include "ssh.h"
  80 #include "ssh1.h"
  81 #include "ssh2.h"
  82 #include "compat.h"
  83 #include "cipher.h"
  84 #include "packet.h"
  85 #include "buffer.h"
  86 #include "channels.h"
  87 #include "key.h"
  88 #include "authfd.h"
  89 #include "authfile.h"
  90 #include "pathnames.h"
  91 #include "dispatch.h"
  92 #include "clientloop.h"
  93 #include "log.h"
  94 #include "readconf.h"
  95 #include "sshconnect.h"
  96 #include "misc.h"
  97 #include "kex.h"
  98 #include "mac.h"
  99 #include "sshpty.h"
 100 #include "match.h"
 101 #include "msg.h"
 102 #include "uidswap.h"
 103 #include "roaming.h"
 104 #include "version.h"
 105
 106 #ifdef SMARTCARD
 107 #include "scard.h"
 108 #endif
 109
 110 extern char *__progname;
 111
 112 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 113 int debug_flag = 0;
 114
 115 /* Flag indicating whether a tty should be allocated */
 116 int tty_flag = 0;
 117 int no_tty_flag = 0;
 118 int force_tty_flag = 0;
 119
 120 /* don't exec a shell */
 121 int no_shell_flag = 0;
 122
 123 /*
 124  * Flag indicating that nothing should be read from stdin.  This can be set
 125  * on the command line.
 126  */
 127 int stdin_null_flag = 0;
 128
 129 /*
 130  * Flag indicating that ssh should fork after authentication.  This is useful
 131  * so that the passphrase can be entered manually, and then ssh goes to the
 132  * background.
 133  */
 134 int fork_after_authentication_flag = 0;
 135
 136 /*
 137  * General data structure for command line options and options configurable
 138  * in configuration files.  See readconf.h.
 139  */
 140 Options options;
 141
 142 /* optional user configfile */
 143 char *config = NULL;
 144
 145 /*
 146  * Name of the host we are connecting to.  This is the name given on the
 147  * command line, or the HostName specified for the user-supplied name in a
 148  * configuration file.
 149  */
 150 char *host;
 151
 152 /* socket address the host resolves to */
 153 struct sockaddr_storage hostaddr;
 154
 155 /* Private host keys. */
 156 Sensitive sensitive_data;
 157
 158 /* Original real UID. */
 159 uid_t original_real_uid;
 160 uid_t original_effective_uid;
 161
 162 /* command to be executed */
 163 Buffer command;
 164
 165 /* Should we execute a command or invoke a subsystem? */
 166 int subsystem_flag = 0;
 167
 168 /* # of replies received for global requests */
 169 static int remote_forward_confirms_received = 0;
 170
 171 /* pid of proxycommand child process */
 172 pid_t proxy_command_pid = 0;
 173
 174 /* mux.c */
 175 extern int muxserver_sock;
 176 extern u_int muxclient_command;
 177
 178 /* Prints a help message to the user.  This function never returns. */
 179
 180 static void
 181 usage(void)
 182 {
 183         fprintf(stderr,
 184 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
 185 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 186 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 187 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 188 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 189 "           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
 190         );
 191         exit(255);
 192 }
 193
 194 static int ssh_session(void);
 195 static int ssh_session2(void);
 196 static void load_public_identity_files(void);
 197
 198 /* from muxclient.c */
 199 void muxclient(const char *);
 200 void muxserver_listen(void);
 201
 202 /*
 203  * Main program for the ssh client.
 204  */
 205 int
 206 main(int ac, char **av)
 207 {
 208         int i, r, opt, exit_status, use_syslog;
 209         char *p, *cp, *line, *argv0, buf[MAXPATHLEN];
 210         struct stat st;
 211         struct passwd *pw;
 212         int dummy, timeout_ms;
 213         extern int optind, optreset;
 214         extern char *optarg;
 215         struct servent *sp;
 216         Forward fwd;
 217
 218         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 219         sanitise_stdfd();
 220
 221         __progname = ssh_get_progname(av[0]);
 222         init_rng();
 223
 224         /*
 225          * Save the original real uid.  It will be needed later (uid-swapping
 226          * may clobber the real uid).
 227          */
 228         original_real_uid = getuid();
 229         original_effective_uid = geteuid();
 230
 231         /*
 232          * Use uid-swapping to give up root privileges for the duration of
 233          * option processing.  We will re-instantiate the rights when we are
 234          * ready to create the privileged port, and will permanently drop
 235          * them when the port has been created (actually, when the connection
 236          * has been made, as we may need to create the port several times).
 237          */
 238         PRIV_END;
 239
 240 #ifdef HAVE_SETRLIMIT
 241         /* If we are installed setuid root be careful to not drop core. */
 242         if (original_real_uid != original_effective_uid) {
 243                 struct rlimit rlim;
 244                 rlim.rlim_cur = rlim.rlim_max = 0;
 245                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 246                         fatal("setrlimit failed: %.100s", strerror(errno));
 247         }
 248 #endif
 249         /* Get user data. */
 250         pw = getpwuid(original_real_uid);
 251         if (!pw) {
 252                 logit("You don't exist, go away!");
 253                 exit(255);
 254         }
 255         /* Take a copy of the returned structure. */
 256         pw = pwcopy(pw);
 257
 258         /*
 259          * Set our umask to something reasonable, as some files are created
 260          * with the default umask.  This will make them world-readable but
 261          * writable only by the owner, which is ok for all files for which we
 262          * don't set the modes explicitly.
 263          */
 264         umask(022);
 265
 266         /*
 267          * Initialize option structure to indicate that no values have been
 268          * set.
 269          */
 270         initialize_options(&options);
 271
 272         /* Parse command-line arguments. */
 273         host = NULL;
 274         use_syslog = 0;
 275         argv0 = av[0];
 276
 277  again:
 278         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 279             "ACD:F:I:KL:MNO:PR:S:TVw:XYy")) != -1) {
 280                 switch (opt) {
 281                 case '1':
 282                         options.protocol = SSH_PROTO_1;
 283                         break;
 284                 case '2':
 285                         options.protocol = SSH_PROTO_2;
 286                         break;
 287                 case '4':
 288                         options.address_family = AF_INET;
 289                         break;
 290                 case '6':
 291                         options.address_family = AF_INET6;
 292                         break;
 293                 case 'n':
 294                         stdin_null_flag = 1;
 295                         break;
 296                 case 'f':
 297                         fork_after_authentication_flag = 1;
 298                         stdin_null_flag = 1;
 299                         break;
 300                 case 'x':
 301                         options.forward_x11 = 0;
 302                         break;
 303                 case 'X':
 304                         options.forward_x11 = 1;
 305                         break;
 306                 case 'y':
 307                         use_syslog = 1;
 308                         break;
 309                 case 'Y':
 310                         options.forward_x11 = 1;
 311                         options.forward_x11_trusted = 1;
 312                         break;
 313                 case 'g':
 314                         options.gateway_ports = 1;
 315                         break;
 316                 case 'O':
 317                         if (strcmp(optarg, "check") == 0)
 318                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 319                         else if (strcmp(optarg, "exit") == 0)
 320                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 321                         else
 322                                 fatal("Invalid multiplex command.");
 323                         break;
 324                 case 'P':       /* deprecated */
 325                         options.use_privileged_port = 0;
 326                         break;
 327                 case 'a':
 328                         options.forward_agent = 0;
 329                         break;
 330                 case 'A':
 331                         options.forward_agent = 1;
 332                         break;
 333                 case 'k':
 334                         options.gss_deleg_creds = 0;
 335                         break;
 336                 case 'K':
 337                         options.gss_authentication = 1;
 338                         options.gss_deleg_creds = 1;
 339                         break;
 340                 case 'i':
 341                         if (stat(optarg, &st) < 0) {
 342                                 fprintf(stderr, "Warning: Identity file %s "
 343                                     "not accessible: %s.\n", optarg,
 344                                     strerror(errno));
 345                                 break;
 346                         }
 347                         if (options.num_identity_files >=
 348                             SSH_MAX_IDENTITY_FILES)
 349                                 fatal("Too many identity files specified "
 350                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 351                         options.identity_files[options.num_identity_files++] =
 352                             xstrdup(optarg);
 353                         break;
 354                 case 'I':
 355 #ifdef SMARTCARD
 356                         options.smartcard_device = xstrdup(optarg);
 357 #else
 358                         fprintf(stderr, "no support for smartcards.\n");
 359 #endif
 360                         break;
 361                 case 't':
 362                         if (tty_flag)
 363                                 force_tty_flag = 1;
 364                         tty_flag = 1;
 365                         break;
 366                 case 'v':
 367                         if (debug_flag == 0) {
 368                                 debug_flag = 1;
 369                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 370                         } else {
 371                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 372                                         options.log_level++;
 373                                 break;
 374                         }
 375                         /* FALLTHROUGH */
 376                 case 'V':
 377                         fprintf(stderr, "%s, %s\n",
 378                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 379                         if (opt == 'V')
 380                                 exit(0);
 381                         break;
 382                 case 'w':
 383                         if (options.tun_open == -1)
 384                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 385                         options.tun_local = a2tun(optarg, &options.tun_remote);
 386                         if (options.tun_local == SSH_TUNID_ERR) {
 387                                 fprintf(stderr,
 388                                     "Bad tun device '%s'\n", optarg);
 389                                 exit(255);
 390                         }
 391                         break;
 392                 case 'q':
 393                         options.log_level = SYSLOG_LEVEL_QUIET;
 394                         break;
 395                 case 'e':
 396                         if (optarg[0] == '^' && optarg[2] == 0 &&
 397                             (u_char) optarg[1] >= 64 &&
 398                             (u_char) optarg[1] < 128)
 399                                 options.escape_char = (u_char) optarg[1] & 31;
 400                         else if (strlen(optarg) == 1)
 401                                 options.escape_char = (u_char) optarg[0];
 402                         else if (strcmp(optarg, "none") == 0)
 403                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 404                         else {
 405                                 fprintf(stderr, "Bad escape character '%s'.\n",
 406                                     optarg);
 407                                 exit(255);
 408                         }
 409                         break;
 410                 case 'c':
 411                         if (ciphers_valid(optarg)) {
 412                                 /* SSH2 only */
 413                                 options.ciphers = xstrdup(optarg);
 414                                 options.cipher = SSH_CIPHER_INVALID;
 415                         } else {
 416                                 /* SSH1 only */
 417                                 options.cipher = cipher_number(optarg);
 418                                 if (options.cipher == -1) {
 419                                         fprintf(stderr,
 420                                             "Unknown cipher type '%s'\n",
 421                                             optarg);
 422                                         exit(255);
 423                                 }
 424                                 if (options.cipher == SSH_CIPHER_3DES)
 425                                         options.ciphers = "3des-cbc";
 426                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 427                                         options.ciphers = "blowfish-cbc";
 428                                 else
 429                                         options.ciphers = (char *)-1;
 430                         }
 431                         break;
 432                 case 'm':
 433                         if (mac_valid(optarg))
 434                                 options.macs = xstrdup(optarg);
 435                         else {
 436                                 fprintf(stderr, "Unknown mac type '%s'\n",
 437                                     optarg);
 438                                 exit(255);
 439                         }
 440                         break;
 441                 case 'M':
 442                         if (options.control_master == SSHCTL_MASTER_YES)
 443                                 options.control_master = SSHCTL_MASTER_ASK;
 444                         else
 445                                 options.control_master = SSHCTL_MASTER_YES;
 446                         break;
 447                 case 'p':
 448                         options.port = a2port(optarg);
 449                         if (options.port <= 0) {
 450                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 451                                 exit(255);
 452                         }
 453                         break;
 454                 case 'l':
 455                         options.user = optarg;
 456                         break;
 457
 458                 case 'L':
 459                         if (parse_forward(&fwd, optarg, 0, 0))
 460                                 add_local_forward(&options, &fwd);
 461                         else {
 462                                 fprintf(stderr,
 463                                     "Bad local forwarding specification '%s'\n",
 464                                     optarg);
 465                                 exit(255);
 466                         }
 467                         break;
 468
 469                 case 'R':
 470                         if (parse_forward(&fwd, optarg, 0, 1)) {
 471                                 add_remote_forward(&options, &fwd);
 472                         } else {
 473                                 fprintf(stderr,
 474                                     "Bad remote forwarding specification "
 475                                     "'%s'\n", optarg);
 476                                 exit(255);
 477                         }
 478                         break;
 479
 480                 case 'D':
 481                         if (parse_forward(&fwd, optarg, 1, 0)) {
 482                                 add_local_forward(&options, &fwd);
 483                         } else {
 484                                 fprintf(stderr,
 485                                     "Bad dynamic forwarding specification "
 486                                     "'%s'\n", optarg);
 487                                 exit(255);
 488                         }
 489                         break;
 490
 491                 case 'C':
 492                         options.compression = 1;
 493                         break;
 494                 case 'N':
 495                         no_shell_flag = 1;
 496                         no_tty_flag = 1;
 497                         break;
 498                 case 'T':
 499                         no_tty_flag = 1;
 500                         break;
 501                 case 'o':
 502                         dummy = 1;
 503                         line = xstrdup(optarg);
 504                         if (process_config_line(&options, host ? host : "",
 505                             line, "command-line", 0, &dummy) != 0)
 506                                 exit(255);
 507                         xfree(line);
 508                         break;
 509                 case 's':
 510                         subsystem_flag = 1;
 511                         break;
 512                 case 'S':
 513                         if (options.control_path != NULL)
 514                                 free(options.control_path);
 515                         options.control_path = xstrdup(optarg);
 516                         break;
 517                 case 'b':
 518                         options.bind_address = optarg;
 519                         break;
 520                 case 'F':
 521                         config = optarg;
 522                         break;
 523                 default:
 524                         usage();
 525                 }
 526         }
 527
 528         ac -= optind;
 529         av += optind;
 530
 531         if (ac > 0 && !host) {
 532                 if (strrchr(*av, '@')) {
 533                         p = xstrdup(*av);
 534                         cp = strrchr(p, '@');
 535                         if (cp == NULL || cp == p)
 536                                 usage();
 537                         options.user = p;
 538                         *cp = '\0';
 539                         host = ++cp;
 540                 } else
 541                         host = *av;
 542                 if (ac > 1) {
 543                         optind = optreset = 1;
 544                         goto again;
 545                 }
 546                 ac--, av++;
 547         }
 548
 549         /* Check that we got a host name. */
 550         if (!host)
 551                 usage();
 552
 553         SSLeay_add_all_algorithms();
 554         ERR_load_crypto_strings();
 555
 556         /* Initialize the command to execute on remote host. */
 557         buffer_init(&command);
 558
 559         /*
 560          * Save the command to execute on the remote host in a buffer. There
 561          * is no limit on the length of the command, except by the maximum
 562          * packet size.  Also sets the tty flag if there is no command.
 563          */
 564         if (!ac) {
 565                 /* No command specified - execute shell on a tty. */
 566                 tty_flag = 1;
 567                 if (subsystem_flag) {
 568                         fprintf(stderr,
 569                             "You must specify a subsystem to invoke.\n");
 570                         usage();
 571                 }
 572         } else {
 573                 /* A command has been specified.  Store it into the buffer. */
 574                 for (i = 0; i < ac; i++) {
 575                         if (i)
 576                                 buffer_append(&command, " ", 1);
 577                         buffer_append(&command, av[i], strlen(av[i]));
 578                 }
 579         }
 580
 581         /* Cannot fork to background if no command. */
 582         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 583             !no_shell_flag)
 584                 fatal("Cannot fork into background without a command "
 585                     "to execute.");
 586
 587         /* Allocate a tty by default if no command specified. */
 588         if (buffer_len(&command) == 0)
 589                 tty_flag = 1;
 590
 591         /* Force no tty */
 592         if (no_tty_flag)
 593                 tty_flag = 0;
 594         /* Do not allocate a tty if stdin is not a tty. */
 595         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 596                 if (tty_flag)
 597                         logit("Pseudo-terminal will not be allocated because "
 598                             "stdin is not a terminal.");
 599                 tty_flag = 0;
 600         }
 601
 602         /*
 603          * Initialize "log" output.  Since we are the client all output
 604          * actually goes to stderr.
 605          */
 606         log_init(argv0,
 607             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 608             SYSLOG_FACILITY_USER, !use_syslog);
 609
 610         /*
 611          * Read per-user configuration file.  Ignore the system wide config
 612          * file if the user specifies a config file on the command line.
 613          */
 614         if (config != NULL) {
 615                 if (!read_config_file(config, host, &options, 0))
 616                         fatal("Can't open user config file %.100s: "
 617                             "%.100s", config, strerror(errno));
 618         } else {
 619                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 620                     _PATH_SSH_USER_CONFFILE);
 621                 if (r > 0 && (size_t)r < sizeof(buf))
 622                         (void)read_config_file(buf, host, &options, 1);
 623
 624                 /* Read systemwide configuration file after use config. */
 625                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 626                     &options, 0);
 627         }
 628
 629         /* Fill configuration defaults. */
 630         fill_default_options(&options);
 631
 632         channel_set_af(options.address_family);
 633
 634         /* reinit */
 635         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 636
 637         seed_rng();
 638
 639         if (options.user == NULL)
 640                 options.user = xstrdup(pw->pw_name);
 641
 642         /* Get default port if port has not been set. */
 643         if (options.port == 0) {
 644                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 645                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 646         }
 647
 648         if (options.local_command != NULL) {
 649                 char thishost[NI_MAXHOST];
 650
 651                 if (gethostname(thishost, sizeof(thishost)) == -1)
 652                         fatal("gethostname: %s", strerror(errno));
 653                 snprintf(buf, sizeof(buf), "%d", options.port);
 654                 debug3("expanding LocalCommand: %s", options.local_command);
 655                 cp = options.local_command;
 656                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 657                     "h", options.hostname? options.hostname : host,
 658                     "l", thishost, "n", host, "r", options.user, "p", buf,
 659                     "u", pw->pw_name, (char *)NULL);
 660                 debug3("expanded LocalCommand: %s", options.local_command);
 661                 xfree(cp);
 662         }
 663
 664         if (options.hostname != NULL)
 665                 host = options.hostname;
 666
 667         /* force lowercase for hostkey matching */
 668         if (options.host_key_alias != NULL) {
 669                 for (p = options.host_key_alias; *p; p++)
 670                         if (isupper(*p))
 671                                 *p = (char)tolower(*p);
 672         }
 673
 674         if (options.proxy_command != NULL &&
 675             strcmp(options.proxy_command, "none") == 0) {
 676                 xfree(options.proxy_command);
 677                 options.proxy_command = NULL;
 678         }
 679         if (options.control_path != NULL &&
 680             strcmp(options.control_path, "none") == 0) {
 681                 xfree(options.control_path);
 682                 options.control_path = NULL;
 683         }
 684
 685         if (options.control_path != NULL) {
 686                 char thishost[NI_MAXHOST];
 687
 688                 if (gethostname(thishost, sizeof(thishost)) == -1)
 689                         fatal("gethostname: %s", strerror(errno));
 690                 snprintf(buf, sizeof(buf), "%d", options.port);
 691                 cp = tilde_expand_filename(options.control_path,
 692                     original_real_uid);
 693                 xfree(options.control_path);
 694                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 695                     "r", options.user, "l", thishost, (char *)NULL);
 696                 xfree(cp);
 697         }
 698         if (muxclient_command != 0 && options.control_path == NULL)
 699                 fatal("No ControlPath specified for \"-O\" command");
 700         if (options.control_path != NULL)
 701                 muxclient(options.control_path);
 702
 703         timeout_ms = options.connection_timeout * 1000;
 704
 705         /* Open a connection to the remote host. */
 706         if (ssh_connect(host, &hostaddr, options.port,
 707             options.address_family, options.connection_attempts, &timeout_ms,
 708             options.tcp_keep_alive,
 709 #ifdef HAVE_CYGWIN
 710             options.use_privileged_port,
 711 #else
 712             original_effective_uid == 0 && options.use_privileged_port,
 713 #endif
 714             options.proxy_command) != 0)
 715                 exit(255);
 716
 717         if (timeout_ms > 0)
 718                 debug3("timeout: %d ms remain after connect", timeout_ms);
 719
 720         /*
 721          * If we successfully made the connection, load the host private key
 722          * in case we will need it later for combined rsa-rhosts
 723          * authentication. This must be done before releasing extra
 724          * privileges, because the file is only readable by root.
 725          * If we cannot access the private keys, load the public keys
 726          * instead and try to execute the ssh-keysign helper instead.
 727          */
 728         sensitive_data.nkeys = 0;
 729         sensitive_data.keys = NULL;
 730         sensitive_data.external_keysign = 0;
 731         if (options.rhosts_rsa_authentication ||
 732             options.hostbased_authentication) {
 733                 sensitive_data.nkeys = 3;
 734                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 735                     sizeof(Key));
 736
 737                 PRIV_START;
 738                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 739                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 740                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 741                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 742                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 743                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 744                 PRIV_END;
 745
 746                 if (options.hostbased_authentication == 1 &&
 747                     sensitive_data.keys[0] == NULL &&
 748                     sensitive_data.keys[1] == NULL &&
 749                     sensitive_data.keys[2] == NULL) {
 750                         sensitive_data.keys[1] = key_load_public(
 751                             _PATH_HOST_DSA_KEY_FILE, NULL);
 752                         sensitive_data.keys[2] = key_load_public(
 753                             _PATH_HOST_RSA_KEY_FILE, NULL);
 754                         sensitive_data.external_keysign = 1;
 755                 }
 756         }
 757         /*
 758          * Get rid of any extra privileges that we may have.  We will no
 759          * longer need them.  Also, extra privileges could make it very hard
 760          * to read identity files and other non-world-readable files from the
 761          * user's home directory if it happens to be on a NFS volume where
 762          * root is mapped to nobody.
 763          */
 764         if (original_effective_uid == 0) {
 765                 PRIV_START;
 766                 permanently_set_uid(pw);
 767         }
 768
 769         /*
 770          * Now that we are back to our own permissions, create ~/.ssh
 771          * directory if it doesn't already exist.
 772          */
 773         r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
 774             strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 775         if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0)
 776                 if (mkdir(buf, 0700) < 0)
 777                         error("Could not create directory '%.200s'.", buf);
 778
 779         /* load options.identity_files */
 780         load_public_identity_files();
 781
 782         /* Expand ~ in known host file names. */
 783         /* XXX mem-leaks: */
 784         options.system_hostfile =
 785             tilde_expand_filename(options.system_hostfile, original_real_uid);
 786         options.user_hostfile =
 787             tilde_expand_filename(options.user_hostfile, original_real_uid);
 788         options.system_hostfile2 =
 789             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 790         options.user_hostfile2 =
 791             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 792
 793         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 794
 795         /* Log into the remote system.  Never returns if the login fails. */
 796         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 797             pw, timeout_ms);
 798
 799         /* We no longer need the private host keys.  Clear them now. */
 800         if (sensitive_data.nkeys != 0) {
 801                 for (i = 0; i < sensitive_data.nkeys; i++) {
 802                         if (sensitive_data.keys[i] != NULL) {
 803                                 /* Destroys contents safely */
 804                                 debug3("clear hostkey %d", i);
 805                                 key_free(sensitive_data.keys[i]);
 806                                 sensitive_data.keys[i] = NULL;
 807                         }
 808                 }
 809                 xfree(sensitive_data.keys);
 810         }
 811         for (i = 0; i < options.num_identity_files; i++) {
 812                 if (options.identity_files[i]) {
 813                         xfree(options.identity_files[i]);
 814                         options.identity_files[i] = NULL;
 815                 }
 816                 if (options.identity_keys[i]) {
 817                         key_free(options.identity_keys[i]);
 818                         options.identity_keys[i] = NULL;
 819                 }
 820         }
 821
 822         exit_status = compat20 ? ssh_session2() : ssh_session();
 823         packet_close();
 824
 825         if (options.control_path != NULL && muxserver_sock != -1)
 826                 unlink(options.control_path);
 827
 828         /*
 829          * Send SIGHUP to proxy command if used. We don't wait() in
 830          * case it hangs and instead rely on init to reap the child
 831          */
 832         if (proxy_command_pid > 1)
 833                 kill(proxy_command_pid, SIGHUP);
 834
 835         return exit_status;
 836 }
 837
 838 /* Callback for remote forward global requests */
 839 static void
 840 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 841 {
 842         Forward *rfwd = (Forward *)ctxt;
 843
 844         /* XXX verbose() on failure? */
 845         debug("remote forward %s for: listen %d, connect %s:%d",
 846             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
 847             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
 848         if (type == SSH2_MSG_REQUEST_SUCCESS && rfwd->listen_port == 0) {
 849                 logit("Allocated port %u for remote forward to %s:%d",
 850                         packet_get_int(),
 851                         rfwd->connect_host, rfwd->connect_port);
 852         }
 853
 854         if (type == SSH2_MSG_REQUEST_FAILURE) {
 855                 if (options.exit_on_forward_failure)
 856                         fatal("Error: remote port forwarding failed for "
 857                             "listen port %d", rfwd->listen_port);
 858                 else
 859                         logit("Warning: remote port forwarding failed for "
 860                             "listen port %d", rfwd->listen_port);
 861         }
 862         if (++remote_forward_confirms_received == options.num_remote_forwards) {
 863                 debug("All remote forwarding requests processed");
 864                 if (fork_after_authentication_flag) {
 865                         fork_after_authentication_flag = 0;
 866                         if (daemon(1, 1) < 0)
 867                                 fatal("daemon() failed: %.200s",
 868                                     strerror(errno));
 869                 }
 870         }
 871 }
 872
 873 static void
 874 ssh_init_forwarding(void)
 875 {
 876         int success = 0;
 877         int i;
 878
 879         /* Initiate local TCP/IP port forwardings. */
 880         for (i = 0; i < options.num_local_forwards; i++) {
 881                 debug("Local connections to %.200s:%d forwarded to remote "
 882                     "address %.200s:%d",
 883                     (options.local_forwards[i].listen_host == NULL) ?
 884                     (options.gateway_ports ? "*" : "LOCALHOST") :
 885                     options.local_forwards[i].listen_host,
 886                     options.local_forwards[i].listen_port,
 887                     options.local_forwards[i].connect_host,
 888                     options.local_forwards[i].connect_port);
 889                 success += channel_setup_local_fwd_listener(
 890                     options.local_forwards[i].listen_host,
 891                     options.local_forwards[i].listen_port,
 892                     options.local_forwards[i].connect_host,
 893                     options.local_forwards[i].connect_port,
 894                     options.gateway_ports);
 895         }
 896         if (i > 0 && success != i && options.exit_on_forward_failure)
 897                 fatal("Could not request local forwarding.");
 898         if (i > 0 && success == 0)
 899                 error("Could not request local forwarding.");
 900
 901         /* Initiate remote TCP/IP port forwardings. */
 902         for (i = 0; i < options.num_remote_forwards; i++) {
 903                 debug("Remote connections from %.200s:%d forwarded to "
 904                     "local address %.200s:%d",
 905                     (options.remote_forwards[i].listen_host == NULL) ?
 906                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 907                     options.remote_forwards[i].listen_port,
 908                     options.remote_forwards[i].connect_host,
 909                     options.remote_forwards[i].connect_port);
 910                 if (channel_request_remote_forwarding(
 911                     options.remote_forwards[i].listen_host,
 912                     options.remote_forwards[i].listen_port,
 913                     options.remote_forwards[i].connect_host,
 914                     options.remote_forwards[i].connect_port) < 0) {
 915                         if (options.exit_on_forward_failure)
 916                                 fatal("Could not request remote forwarding.");
 917                         else
 918                                 logit("Warning: Could not request remote "
 919                                     "forwarding.");
 920                 }
 921                 client_register_global_confirm(ssh_confirm_remote_forward,
 922                     &options.remote_forwards[i]);
 923         }
 924
 925         /* Initiate tunnel forwarding. */
 926         if (options.tun_open != SSH_TUNMODE_NO) {
 927                 if (client_request_tun_fwd(options.tun_open,
 928                     options.tun_local, options.tun_remote) == -1) {
 929                         if (options.exit_on_forward_failure)
 930                                 fatal("Could not request tunnel forwarding.");
 931                         else
 932                                 error("Could not request tunnel forwarding.");
 933                 }
 934         }
 935 }
 936
 937 static void
 938 check_agent_present(void)
 939 {
 940         if (options.forward_agent) {
 941                 /* Clear agent forwarding if we don't have an agent. */
 942                 if (!ssh_agent_present())
 943                         options.forward_agent = 0;
 944         }
 945 }
 946
 947 static int
 948 ssh_session(void)
 949 {
 950         int type;
 951         int interactive = 0;
 952         int have_tty = 0;
 953         struct winsize ws;
 954         char *cp;
 955         const char *display;
 956
 957         /* Enable compression if requested. */
 958         if (options.compression) {
 959                 debug("Requesting compression at level %d.",
 960                     options.compression_level);
 961
 962                 if (options.compression_level < 1 ||
 963                     options.compression_level > 9)
 964                         fatal("Compression level must be from 1 (fast) to "
 965                             "9 (slow, best).");
 966
 967                 /* Send the request. */
 968                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 969                 packet_put_int(options.compression_level);
 970                 packet_send();
 971                 packet_write_wait();
 972                 type = packet_read();
 973                 if (type == SSH_SMSG_SUCCESS)
 974                         packet_start_compression(options.compression_level);
 975                 else if (type == SSH_SMSG_FAILURE)
 976                         logit("Warning: Remote host refused compression.");
 977                 else
 978                         packet_disconnect("Protocol error waiting for "
 979                             "compression response.");
 980         }
 981         /* Allocate a pseudo tty if appropriate. */
 982         if (tty_flag) {
 983                 debug("Requesting pty.");
 984
 985                 /* Start the packet. */
 986                 packet_start(SSH_CMSG_REQUEST_PTY);
 987
 988                 /* Store TERM in the packet.  There is no limit on the
 989                    length of the string. */
 990                 cp = getenv("TERM");
 991                 if (!cp)
 992                         cp = "";
 993                 packet_put_cstring(cp);
 994
 995                 /* Store window size in the packet. */
 996                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 997                         memset(&ws, 0, sizeof(ws));
 998                 packet_put_int((u_int)ws.ws_row);
 999                 packet_put_int((u_int)ws.ws_col);
1000                 packet_put_int((u_int)ws.ws_xpixel);
1001                 packet_put_int((u_int)ws.ws_ypixel);
1002
1003                 /* Store tty modes in the packet. */
1004                 tty_make_modes(fileno(stdin), NULL);
1005
1006                 /* Send the packet, and wait for it to leave. */
1007                 packet_send();
1008                 packet_write_wait();
1009
1010                 /* Read response from the server. */
1011                 type = packet_read();
1012                 if (type == SSH_SMSG_SUCCESS) {
1013                         interactive = 1;
1014                         have_tty = 1;
1015                 } else if (type == SSH_SMSG_FAILURE)
1016                         logit("Warning: Remote host failed or refused to "
1017                             "allocate a pseudo tty.");
1018                 else
1019                         packet_disconnect("Protocol error waiting for pty "
1020                             "request response.");
1021         }
1022         /* Request X11 forwarding if enabled and DISPLAY is set. */
1023         display = getenv("DISPLAY");
1024         if (options.forward_x11 && display != NULL) {
1025                 char *proto, *data;
1026                 /* Get reasonable local authentication information. */
1027                 client_x11_get_proto(display, options.xauth_location,
1028                     options.forward_x11_trusted, &proto, &data);
1029                 /* Request forwarding with authentication spoofing. */
1030                 debug("Requesting X11 forwarding with authentication "
1031                     "spoofing.");
1032                 x11_request_forwarding_with_spoofing(0, display, proto, data);
1033
1034                 /* Read response from the server. */
1035                 type = packet_read();
1036                 if (type == SSH_SMSG_SUCCESS) {
1037                         interactive = 1;
1038                 } else if (type == SSH_SMSG_FAILURE) {
1039                         logit("Warning: Remote host denied X11 forwarding.");
1040                 } else {
1041                         packet_disconnect("Protocol error waiting for X11 "
1042                             "forwarding");
1043                 }
1044         }
1045         /* Tell the packet module whether this is an interactive session. */
1046         packet_set_interactive(interactive);
1047
1048         /* Request authentication agent forwarding if appropriate. */
1049         check_agent_present();
1050
1051         if (options.forward_agent) {
1052                 debug("Requesting authentication agent forwarding.");
1053                 auth_request_forwarding();
1054
1055                 /* Read response from the server. */
1056                 type = packet_read();
1057                 packet_check_eom();
1058                 if (type != SSH_SMSG_SUCCESS)
1059                         logit("Warning: Remote host denied authentication agent forwarding.");
1060         }
1061
1062         /* Initiate port forwardings. */
1063         ssh_init_forwarding();
1064
1065         /* Execute a local command */
1066         if (options.local_command != NULL &&
1067             options.permit_local_command)
1068                 ssh_local_cmd(options.local_command);
1069
1070         /*
1071          * If requested and we are not interested in replies to remote
1072          * forwarding requests, then let ssh continue in the background.
1073          */
1074         if (fork_after_authentication_flag &&
1075             (!options.exit_on_forward_failure ||
1076             options.num_remote_forwards == 0)) {
1077                 fork_after_authentication_flag = 0;
1078                 if (daemon(1, 1) < 0)
1079                         fatal("daemon() failed: %.200s", strerror(errno));
1080         }
1081
1082         /*
1083          * If a command was specified on the command line, execute the
1084          * command now. Otherwise request the server to start a shell.
1085          */
1086         if (buffer_len(&command) > 0) {
1087                 int len = buffer_len(&command);
1088                 if (len > 900)
1089                         len = 900;
1090                 debug("Sending command: %.*s", len,
1091                     (u_char *)buffer_ptr(&command));
1092                 packet_start(SSH_CMSG_EXEC_CMD);
1093                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1094                 packet_send();
1095                 packet_write_wait();
1096         } else {
1097                 debug("Requesting shell.");
1098                 packet_start(SSH_CMSG_EXEC_SHELL);
1099                 packet_send();
1100                 packet_write_wait();
1101         }
1102
1103         /* Enter the interactive session. */
1104         return client_loop(have_tty, tty_flag ?
1105             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1106 }
1107
1108 /* request pty/x11/agent/tcpfwd/shell for channel */
1109 static void
1110 ssh_session2_setup(int id, void *arg)
1111 {
1112         extern char **environ;
1113         const char *display;
1114         int interactive = tty_flag;
1115
1116         display = getenv("DISPLAY");
1117         if (options.forward_x11 && display != NULL) {
1118                 char *proto, *data;
1119                 /* Get reasonable local authentication information. */
1120                 client_x11_get_proto(display, options.xauth_location,
1121                     options.forward_x11_trusted, &proto, &data);
1122                 /* Request forwarding with authentication spoofing. */
1123                 debug("Requesting X11 forwarding with authentication "
1124                     "spoofing.");
1125                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1126                 interactive = 1;
1127                 /* XXX wait for reply */
1128         }
1129
1130         check_agent_present();
1131         if (options.forward_agent) {
1132                 debug("Requesting authentication agent forwarding.");
1133                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1134                 packet_send();
1135         }
1136
1137         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1138             NULL, fileno(stdin), &command, environ);
1139
1140         packet_set_interactive(interactive);
1141 }
1142
1143 /* open new channel for a session */
1144 static int
1145 ssh_session2_open(void)
1146 {
1147         Channel *c;
1148         int window, packetmax, in, out, err;
1149
1150         if (stdin_null_flag) {
1151                 in = open(_PATH_DEVNULL, O_RDONLY);
1152         } else {
1153                 in = dup(STDIN_FILENO);
1154         }
1155         out = dup(STDOUT_FILENO);
1156         err = dup(STDERR_FILENO);
1157
1158         if (in < 0 || out < 0 || err < 0)
1159                 fatal("dup() in/out/err failed");
1160
1161         /* enable nonblocking unless tty */
1162         if (!isatty(in))
1163                 set_nonblock(in);
1164         if (!isatty(out))
1165                 set_nonblock(out);
1166         if (!isatty(err))
1167                 set_nonblock(err);
1168
1169         window = CHAN_SES_WINDOW_DEFAULT;
1170         packetmax = CHAN_SES_PACKET_DEFAULT;
1171         if (tty_flag) {
1172                 window >>= 1;
1173                 packetmax >>= 1;
1174         }
1175         c = channel_new(
1176             "session", SSH_CHANNEL_OPENING, in, out, err,
1177             window, packetmax, CHAN_EXTENDED_WRITE,
1178             "client-session", /*nonblock*/0);
1179
1180         debug3("ssh_session2_open: channel_new: %d", c->self);
1181
1182         channel_send_open(c->self);
1183         if (!no_shell_flag)
1184                 channel_register_open_confirm(c->self,
1185                     ssh_session2_setup, NULL);
1186
1187         return c->self;
1188 }
1189
1190 static int
1191 ssh_session2(void)
1192 {
1193         int id = -1;
1194
1195         /* XXX should be pre-session */
1196         ssh_init_forwarding();
1197
1198         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1199                 id = ssh_session2_open();
1200
1201         /* If we don't expect to open a new session, then disallow it */
1202         if (options.control_master == SSHCTL_MASTER_NO &&
1203             (datafellows & SSH_NEW_OPENSSH)) {
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         if (options.use_roaming)
1227                 request_roaming();
1228
1229         return client_loop(tty_flag, tty_flag ?
1230             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1231 }
1232
1233 static void
1234 load_public_identity_files(void)
1235 {
1236         char *filename, *cp, thishost[NI_MAXHOST];
1237         char *pwdir = NULL, *pwname = NULL;
1238         int i = 0;
1239         Key *public;
1240         struct passwd *pw;
1241 #ifdef SMARTCARD
1242         Key **keys;
1243
1244         if (options.smartcard_device != NULL &&
1245             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1246             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL) {
1247                 int count = 0;
1248                 for (i = 0; keys[i] != NULL; i++) {
1249                         count++;
1250                         memmove(&options.identity_files[1],
1251                             &options.identity_files[0],
1252                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1253                         memmove(&options.identity_keys[1],
1254                             &options.identity_keys[0],
1255                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1256                         options.num_identity_files++;
1257                         options.identity_keys[0] = keys[i];
1258                         options.identity_files[0] = sc_get_key_label(keys[i]);
1259                 }
1260                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1261                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1262                 i = count;
1263                 xfree(keys);
1264         }
1265 #endif /* SMARTCARD */
1266         if ((pw = getpwuid(original_real_uid)) == NULL)
1267                 fatal("load_public_identity_files: getpwuid failed");
1268         pwname = xstrdup(pw->pw_name);
1269         pwdir = xstrdup(pw->pw_dir);
1270         if (gethostname(thishost, sizeof(thishost)) == -1)
1271                 fatal("load_public_identity_files: gethostname: %s",
1272                     strerror(errno));
1273         for (; i < options.num_identity_files; i++) {
1274                 cp = tilde_expand_filename(options.identity_files[i],
1275                     original_real_uid);
1276                 filename = percent_expand(cp, "d", pwdir,
1277                     "u", pwname, "l", thishost, "h", host,
1278                     "r", options.user, (char *)NULL);
1279                 xfree(cp);
1280                 public = key_load_public(filename, NULL);
1281                 debug("identity file %s type %d", filename,
1282                     public ? public->type : -1);
1283                 xfree(options.identity_files[i]);
1284                 options.identity_files[i] = filename;
1285                 options.identity_keys[i] = public;
1286         }
1287         bzero(pwname, strlen(pwname));
1288         xfree(pwname);
1289         bzero(pwdir, strlen(pwdir));
1290         xfree(pwdir);
1291 }