openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.326 2009/07/02 02:11:47 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 "version.h"
 104
 105 #ifdef SMARTCARD
 106 #include "scard.h"
 107 #endif
 108
 109 extern char *__progname;
 110
 111 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 112 int debug_flag = 0;
 113
 114 /* Flag indicating whether a tty should be allocated */
 115 int tty_flag = 0;
 116 int no_tty_flag = 0;
 117 int force_tty_flag = 0;
 118
 119 /* don't exec a shell */
 120 int no_shell_flag = 0;
 121
 122 /*
 123  * Flag indicating that nothing should be read from stdin.  This can be set
 124  * on the command line.
 125  */
 126 int stdin_null_flag = 0;
 127
 128 /*
 129  * Flag indicating that ssh should fork after authentication.  This is useful
 130  * so that the passphrase can be entered manually, and then ssh goes to the
 131  * background.
 132  */
 133 int fork_after_authentication_flag = 0;
 134
 135 /*
 136  * General data structure for command line options and options configurable
 137  * in configuration files.  See readconf.h.
 138  */
 139 Options options;
 140
 141 /* optional user configfile */
 142 char *config = NULL;
 143
 144 /*
 145  * Name of the host we are connecting to.  This is the name given on the
 146  * command line, or the HostName specified for the user-supplied name in a
 147  * configuration file.
 148  */
 149 char *host;
 150
 151 /* socket address the host resolves to */
 152 struct sockaddr_storage hostaddr;
 153
 154 /* Private host keys. */
 155 Sensitive sensitive_data;
 156
 157 /* Original real UID. */
 158 uid_t original_real_uid;
 159 uid_t original_effective_uid;
 160
 161 /* command to be executed */
 162 Buffer command;
 163
 164 /* Should we execute a command or invoke a subsystem? */
 165 int subsystem_flag = 0;
 166
 167 /* # of replies received for global requests */
 168 static int remote_forward_confirms_received = 0;
 169
 170 /* pid of proxycommand child process */
 171 pid_t proxy_command_pid = 0;
 172
 173 /* mux.c */
 174 extern int muxserver_sock;
 175 extern u_int muxclient_command;
 176
 177 /* Prints a help message to the user.  This function never returns. */
 178
 179 static void
 180 usage(void)
 181 {
 182         fprintf(stderr,
 183 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
 184 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 185 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 186 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 187 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 188 "           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
 189         );
 190         exit(255);
 191 }
 192
 193 static int ssh_session(void);
 194 static int ssh_session2(void);
 195 static void load_public_identity_files(void);
 196
 197 /* from muxclient.c */
 198 void muxclient(const char *);
 199 void muxserver_listen(void);
 200
 201 /*
 202  * Main program for the ssh client.
 203  */
 204 int
 205 main(int ac, char **av)
 206 {
 207         int i, r, opt, exit_status, use_syslog;
 208         char *p, *cp, *line, *argv0, buf[MAXPATHLEN];
 209         struct stat st;
 210         struct passwd *pw;
 211         int dummy, timeout_ms;
 212         extern int optind, optreset;
 213         extern char *optarg;
 214         struct servent *sp;
 215         Forward fwd;
 216
 217         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 218         sanitise_stdfd();
 219
 220         __progname = ssh_get_progname(av[0]);
 221         init_rng();
 222
 223         /*
 224          * Save the original real uid.  It will be needed later (uid-swapping
 225          * may clobber the real uid).
 226          */
 227         original_real_uid = getuid();
 228         original_effective_uid = geteuid();
 229
 230         /*
 231          * Use uid-swapping to give up root privileges for the duration of
 232          * option processing.  We will re-instantiate the rights when we are
 233          * ready to create the privileged port, and will permanently drop
 234          * them when the port has been created (actually, when the connection
 235          * has been made, as we may need to create the port several times).
 236          */
 237         PRIV_END;
 238
 239 #ifdef HAVE_SETRLIMIT
 240         /* If we are installed setuid root be careful to not drop core. */
 241         if (original_real_uid != original_effective_uid) {
 242                 struct rlimit rlim;
 243                 rlim.rlim_cur = rlim.rlim_max = 0;
 244                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 245                         fatal("setrlimit failed: %.100s", strerror(errno));
 246         }
 247 #endif
 248         /* Get user data. */
 249         pw = getpwuid(original_real_uid);
 250         if (!pw) {
 251                 logit("You don't exist, go away!");
 252                 exit(255);
 253         }
 254         /* Take a copy of the returned structure. */
 255         pw = pwcopy(pw);
 256
 257         /*
 258          * Set our umask to something reasonable, as some files are created
 259          * with the default umask.  This will make them world-readable but
 260          * writable only by the owner, which is ok for all files for which we
 261          * don't set the modes explicitly.
 262          */
 263         umask(022);
 264
 265         /*
 266          * Initialize option structure to indicate that no values have been
 267          * set.
 268          */
 269         initialize_options(&options);
 270
 271         /* Parse command-line arguments. */
 272         host = NULL;
 273         use_syslog = 0;
 274         argv0 = av[0];
 275
 276  again:
 277         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 278             "ACD:F:I:KL:MNO:PR:S:TVw:XYy")) != -1) {
 279                 switch (opt) {
 280                 case '1':
 281                         options.protocol = SSH_PROTO_1;
 282                         break;
 283                 case '2':
 284                         options.protocol = SSH_PROTO_2;
 285                         break;
 286                 case '4':
 287                         options.address_family = AF_INET;
 288                         break;
 289                 case '6':
 290                         options.address_family = AF_INET6;
 291                         break;
 292                 case 'n':
 293                         stdin_null_flag = 1;
 294                         break;
 295                 case 'f':
 296                         fork_after_authentication_flag = 1;
 297                         stdin_null_flag = 1;
 298                         break;
 299                 case 'x':
 300                         options.forward_x11 = 0;
 301                         break;
 302                 case 'X':
 303                         options.forward_x11 = 1;
 304                         break;
 305                 case 'y':
 306                         use_syslog = 1;
 307                         break;
 308                 case 'Y':
 309                         options.forward_x11 = 1;
 310                         options.forward_x11_trusted = 1;
 311                         break;
 312                 case 'g':
 313                         options.gateway_ports = 1;
 314                         break;
 315                 case 'O':
 316                         if (strcmp(optarg, "check") == 0)
 317                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 318                         else if (strcmp(optarg, "exit") == 0)
 319                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 320                         else
 321                                 fatal("Invalid multiplex command.");
 322                         break;
 323                 case 'P':       /* deprecated */
 324                         options.use_privileged_port = 0;
 325                         break;
 326                 case 'a':
 327                         options.forward_agent = 0;
 328                         break;
 329                 case 'A':
 330                         options.forward_agent = 1;
 331                         break;
 332                 case 'k':
 333                         options.gss_deleg_creds = 0;
 334                         break;
 335                 case 'K':
 336                         options.gss_authentication = 1;
 337                         options.gss_deleg_creds = 1;
 338                         break;
 339                 case 'i':
 340                         if (stat(optarg, &st) < 0) {
 341                                 fprintf(stderr, "Warning: Identity file %s "
 342                                     "not accessible: %s.\n", optarg,
 343                                     strerror(errno));
 344                                 break;
 345                         }
 346                         if (options.num_identity_files >=
 347                             SSH_MAX_IDENTITY_FILES)
 348                                 fatal("Too many identity files specified "
 349                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 350                         options.identity_files[options.num_identity_files++] =
 351                             xstrdup(optarg);
 352                         break;
 353                 case 'I':
 354 #ifdef SMARTCARD
 355                         options.smartcard_device = xstrdup(optarg);
 356 #else
 357                         fprintf(stderr, "no support for smartcards.\n");
 358 #endif
 359                         break;
 360                 case 't':
 361                         if (tty_flag)
 362                                 force_tty_flag = 1;
 363                         tty_flag = 1;
 364                         break;
 365                 case 'v':
 366                         if (debug_flag == 0) {
 367                                 debug_flag = 1;
 368                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 369                         } else {
 370                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 371                                         options.log_level++;
 372                                 break;
 373                         }
 374                         /* FALLTHROUGH */
 375                 case 'V':
 376                         fprintf(stderr, "%s, %s\n",
 377                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 378                         if (opt == 'V')
 379                                 exit(0);
 380                         break;
 381                 case 'w':
 382                         if (options.tun_open == -1)
 383                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 384                         options.tun_local = a2tun(optarg, &options.tun_remote);
 385                         if (options.tun_local == SSH_TUNID_ERR) {
 386                                 fprintf(stderr,
 387                                     "Bad tun device '%s'\n", optarg);
 388                                 exit(255);
 389                         }
 390                         break;
 391                 case 'q':
 392                         options.log_level = SYSLOG_LEVEL_QUIET;
 393                         break;
 394                 case 'e':
 395                         if (optarg[0] == '^' && optarg[2] == 0 &&
 396                             (u_char) optarg[1] >= 64 &&
 397                             (u_char) optarg[1] < 128)
 398                                 options.escape_char = (u_char) optarg[1] & 31;
 399                         else if (strlen(optarg) == 1)
 400                                 options.escape_char = (u_char) optarg[0];
 401                         else if (strcmp(optarg, "none") == 0)
 402                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 403                         else {
 404                                 fprintf(stderr, "Bad escape character '%s'.\n",
 405                                     optarg);
 406                                 exit(255);
 407                         }
 408                         break;
 409                 case 'c':
 410                         if (ciphers_valid(optarg)) {
 411                                 /* SSH2 only */
 412                                 options.ciphers = xstrdup(optarg);
 413                                 options.cipher = SSH_CIPHER_INVALID;
 414                         } else {
 415                                 /* SSH1 only */
 416                                 options.cipher = cipher_number(optarg);
 417                                 if (options.cipher == -1) {
 418                                         fprintf(stderr,
 419                                             "Unknown cipher type '%s'\n",
 420                                             optarg);
 421                                         exit(255);
 422                                 }
 423                                 if (options.cipher == SSH_CIPHER_3DES)
 424                                         options.ciphers = "3des-cbc";
 425                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 426                                         options.ciphers = "blowfish-cbc";
 427                                 else
 428                                         options.ciphers = (char *)-1;
 429                         }
 430                         break;
 431                 case 'm':
 432                         if (mac_valid(optarg))
 433                                 options.macs = xstrdup(optarg);
 434                         else {
 435                                 fprintf(stderr, "Unknown mac type '%s'\n",
 436                                     optarg);
 437                                 exit(255);
 438                         }
 439                         break;
 440                 case 'M':
 441                         if (options.control_master == SSHCTL_MASTER_YES)
 442                                 options.control_master = SSHCTL_MASTER_ASK;
 443                         else
 444                                 options.control_master = SSHCTL_MASTER_YES;
 445                         break;
 446                 case 'p':
 447                         options.port = a2port(optarg);
 448                         if (options.port <= 0) {
 449                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 450                                 exit(255);
 451                         }
 452                         break;
 453                 case 'l':
 454                         options.user = optarg;
 455                         break;
 456
 457                 case 'L':
 458                         if (parse_forward(&fwd, optarg, 0, 0))
 459                                 add_local_forward(&options, &fwd);
 460                         else {
 461                                 fprintf(stderr,
 462                                     "Bad local forwarding specification '%s'\n",
 463                                     optarg);
 464                                 exit(255);
 465                         }
 466                         break;
 467
 468                 case 'R':
 469                         if (parse_forward(&fwd, optarg, 0, 1)) {
 470                                 add_remote_forward(&options, &fwd);
 471                         } else {
 472                                 fprintf(stderr,
 473                                     "Bad remote forwarding specification "
 474                                     "'%s'\n", optarg);
 475                                 exit(255);
 476                         }
 477                         break;
 478
 479                 case 'D':
 480                         if (parse_forward(&fwd, optarg, 1, 0)) {
 481                                 add_local_forward(&options, &fwd);
 482                         } else {
 483                                 fprintf(stderr,
 484                                     "Bad dynamic forwarding specification "
 485                                     "'%s'\n", optarg);
 486                                 exit(255);
 487                         }
 488                         break;
 489
 490                 case 'C':
 491                         options.compression = 1;
 492                         break;
 493                 case 'N':
 494                         no_shell_flag = 1;
 495                         no_tty_flag = 1;
 496                         break;
 497                 case 'T':
 498                         no_tty_flag = 1;
 499                         break;
 500                 case 'o':
 501                         dummy = 1;
 502                         line = xstrdup(optarg);
 503                         if (process_config_line(&options, host ? host : "",
 504                             line, "command-line", 0, &dummy) != 0)
 505                                 exit(255);
 506                         xfree(line);
 507                         break;
 508                 case 's':
 509                         subsystem_flag = 1;
 510                         break;
 511                 case 'S':
 512                         if (options.control_path != NULL)
 513                                 free(options.control_path);
 514                         options.control_path = xstrdup(optarg);
 515                         break;
 516                 case 'b':
 517                         options.bind_address = optarg;
 518                         break;
 519                 case 'F':
 520                         config = optarg;
 521                         break;
 522                 default:
 523                         usage();
 524                 }
 525         }
 526
 527         ac -= optind;
 528         av += optind;
 529
 530         if (ac > 0 && !host && **av != '-') {
 531                 if (strrchr(*av, '@')) {
 532                         p = xstrdup(*av);
 533                         cp = strrchr(p, '@');
 534                         if (cp == NULL || cp == p)
 535                                 usage();
 536                         options.user = p;
 537                         *cp = '\0';
 538                         host = ++cp;
 539                 } else
 540                         host = *av;
 541                 if (ac > 1) {
 542                         optind = optreset = 1;
 543                         goto again;
 544                 }
 545                 ac--, av++;
 546         }
 547
 548         /* Check that we got a host name. */
 549         if (!host)
 550                 usage();
 551
 552         SSLeay_add_all_algorithms();
 553         ERR_load_crypto_strings();
 554
 555         /* Initialize the command to execute on remote host. */
 556         buffer_init(&command);
 557
 558         /*
 559          * Save the command to execute on the remote host in a buffer. There
 560          * is no limit on the length of the command, except by the maximum
 561          * packet size.  Also sets the tty flag if there is no command.
 562          */
 563         if (!ac) {
 564                 /* No command specified - execute shell on a tty. */
 565                 tty_flag = 1;
 566                 if (subsystem_flag) {
 567                         fprintf(stderr,
 568                             "You must specify a subsystem to invoke.\n");
 569                         usage();
 570                 }
 571         } else {
 572                 /* A command has been specified.  Store it into the buffer. */
 573                 for (i = 0; i < ac; i++) {
 574                         if (i)
 575                                 buffer_append(&command, " ", 1);
 576                         buffer_append(&command, av[i], strlen(av[i]));
 577                 }
 578         }
 579
 580         /* Cannot fork to background if no command. */
 581         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 582             !no_shell_flag)
 583                 fatal("Cannot fork into background without a command "
 584                     "to execute.");
 585
 586         /* Allocate a tty by default if no command specified. */
 587         if (buffer_len(&command) == 0)
 588                 tty_flag = 1;
 589
 590         /* Force no tty */
 591         if (no_tty_flag)
 592                 tty_flag = 0;
 593         /* Do not allocate a tty if stdin is not a tty. */
 594         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 595                 if (tty_flag)
 596                         logit("Pseudo-terminal will not be allocated because "
 597                             "stdin is not a terminal.");
 598                 tty_flag = 0;
 599         }
 600
 601         /*
 602          * Initialize "log" output.  Since we are the client all output
 603          * actually goes to stderr.
 604          */
 605         log_init(argv0,
 606             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 607             SYSLOG_FACILITY_USER, !use_syslog);
 608
 609         /*
 610          * Read per-user configuration file.  Ignore the system wide config
 611          * file if the user specifies a config file on the command line.
 612          */
 613         if (config != NULL) {
 614                 if (!read_config_file(config, host, &options, 0))
 615                         fatal("Can't open user config file %.100s: "
 616                             "%.100s", config, strerror(errno));
 617         } else {
 618                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 619                     _PATH_SSH_USER_CONFFILE);
 620                 if (r > 0 && (size_t)r < sizeof(buf))
 621                         (void)read_config_file(buf, host, &options, 1);
 622
 623                 /* Read systemwide configuration file after use config. */
 624                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 625                     &options, 0);
 626         }
 627
 628         /* Fill configuration defaults. */
 629         fill_default_options(&options);
 630
 631         channel_set_af(options.address_family);
 632
 633         /* reinit */
 634         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 635
 636         seed_rng();
 637
 638         if (options.user == NULL)
 639                 options.user = xstrdup(pw->pw_name);
 640
 641         /* Get default port if port has not been set. */
 642         if (options.port == 0) {
 643                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 644                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 645         }
 646
 647         if (options.local_command != NULL) {
 648                 char thishost[NI_MAXHOST];
 649
 650                 if (gethostname(thishost, sizeof(thishost)) == -1)
 651                         fatal("gethostname: %s", strerror(errno));
 652                 snprintf(buf, sizeof(buf), "%d", options.port);
 653                 debug3("expanding LocalCommand: %s", options.local_command);
 654                 cp = options.local_command;
 655                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 656                     "h", options.hostname? options.hostname : host,
 657                     "l", thishost, "n", host, "r", options.user, "p", buf,
 658                     "u", pw->pw_name, (char *)NULL);
 659                 debug3("expanded LocalCommand: %s", options.local_command);
 660                 xfree(cp);
 661         }
 662
 663         if (options.hostname != NULL)
 664                 host = options.hostname;
 665
 666         /* force lowercase for hostkey matching */
 667         if (options.host_key_alias != NULL) {
 668                 for (p = options.host_key_alias; *p; p++)
 669                         if (isupper(*p))
 670                                 *p = (char)tolower(*p);
 671         }
 672
 673         if (options.proxy_command != NULL &&
 674             strcmp(options.proxy_command, "none") == 0) {
 675                 xfree(options.proxy_command);
 676                 options.proxy_command = NULL;
 677         }
 678         if (options.control_path != NULL &&
 679             strcmp(options.control_path, "none") == 0) {
 680                 xfree(options.control_path);
 681                 options.control_path = NULL;
 682         }
 683
 684         if (options.control_path != NULL) {
 685                 char thishost[NI_MAXHOST];
 686
 687                 if (gethostname(thishost, sizeof(thishost)) == -1)
 688                         fatal("gethostname: %s", strerror(errno));
 689                 snprintf(buf, sizeof(buf), "%d", options.port);
 690                 cp = tilde_expand_filename(options.control_path,
 691                     original_real_uid);
 692                 xfree(options.control_path);
 693                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 694                     "r", options.user, "l", thishost, (char *)NULL);
 695                 xfree(cp);
 696         }
 697         if (muxclient_command != 0 && options.control_path == NULL)
 698                 fatal("No ControlPath specified for \"-O\" command");
 699         if (options.control_path != NULL)
 700                 muxclient(options.control_path);
 701
 702         timeout_ms = options.connection_timeout * 1000;
 703
 704         /* Open a connection to the remote host. */
 705         if (ssh_connect(host, &hostaddr, options.port,
 706             options.address_family, options.connection_attempts, &timeout_ms,
 707             options.tcp_keep_alive,
 708 #ifdef HAVE_CYGWIN
 709             options.use_privileged_port,
 710 #else
 711             original_effective_uid == 0 && options.use_privileged_port,
 712 #endif
 713             options.proxy_command) != 0)
 714                 exit(255);
 715
 716         if (timeout_ms > 0)
 717                 debug3("timeout: %d ms remain after connect", timeout_ms);
 718
 719         /*
 720          * If we successfully made the connection, load the host private key
 721          * in case we will need it later for combined rsa-rhosts
 722          * authentication. This must be done before releasing extra
 723          * privileges, because the file is only readable by root.
 724          * If we cannot access the private keys, load the public keys
 725          * instead and try to execute the ssh-keysign helper instead.
 726          */
 727         sensitive_data.nkeys = 0;
 728         sensitive_data.keys = NULL;
 729         sensitive_data.external_keysign = 0;
 730         if (options.rhosts_rsa_authentication ||
 731             options.hostbased_authentication) {
 732                 sensitive_data.nkeys = 3;
 733                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 734                     sizeof(Key));
 735
 736                 PRIV_START;
 737                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 738                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 739                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 740                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 741                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 742                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 743                 PRIV_END;
 744
 745                 if (options.hostbased_authentication == 1 &&
 746                     sensitive_data.keys[0] == NULL &&
 747                     sensitive_data.keys[1] == NULL &&
 748                     sensitive_data.keys[2] == NULL) {
 749                         sensitive_data.keys[1] = key_load_public(
 750                             _PATH_HOST_DSA_KEY_FILE, NULL);
 751                         sensitive_data.keys[2] = key_load_public(
 752                             _PATH_HOST_RSA_KEY_FILE, NULL);
 753                         sensitive_data.external_keysign = 1;
 754                 }
 755         }
 756         /*
 757          * Get rid of any extra privileges that we may have.  We will no
 758          * longer need them.  Also, extra privileges could make it very hard
 759          * to read identity files and other non-world-readable files from the
 760          * user's home directory if it happens to be on a NFS volume where
 761          * root is mapped to nobody.
 762          */
 763         if (original_effective_uid == 0) {
 764                 PRIV_START;
 765                 permanently_set_uid(pw);
 766         }
 767
 768         /*
 769          * Now that we are back to our own permissions, create ~/.ssh
 770          * directory if it doesn't already exist.
 771          */
 772         r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
 773             strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 774         if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0)
 775                 if (mkdir(buf, 0700) < 0)
 776                         error("Could not create directory '%.200s'.", buf);
 777
 778         /* load options.identity_files */
 779         load_public_identity_files();
 780
 781         /* Expand ~ in known host file names. */
 782         /* XXX mem-leaks: */
 783         options.system_hostfile =
 784             tilde_expand_filename(options.system_hostfile, original_real_uid);
 785         options.user_hostfile =
 786             tilde_expand_filename(options.user_hostfile, original_real_uid);
 787         options.system_hostfile2 =
 788             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 789         options.user_hostfile2 =
 790             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 791
 792         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 793
 794         /* Log into the remote system.  Never returns if the login fails. */
 795         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 796             pw, timeout_ms);
 797
 798         /* We no longer need the private host keys.  Clear them now. */
 799         if (sensitive_data.nkeys != 0) {
 800                 for (i = 0; i < sensitive_data.nkeys; i++) {
 801                         if (sensitive_data.keys[i] != NULL) {
 802                                 /* Destroys contents safely */
 803                                 debug3("clear hostkey %d", i);
 804                                 key_free(sensitive_data.keys[i]);
 805                                 sensitive_data.keys[i] = NULL;
 806                         }
 807                 }
 808                 xfree(sensitive_data.keys);
 809         }
 810         for (i = 0; i < options.num_identity_files; i++) {
 811                 if (options.identity_files[i]) {
 812                         xfree(options.identity_files[i]);
 813                         options.identity_files[i] = NULL;
 814                 }
 815                 if (options.identity_keys[i]) {
 816                         key_free(options.identity_keys[i]);
 817                         options.identity_keys[i] = NULL;
 818                 }
 819         }
 820
 821         exit_status = compat20 ? ssh_session2() : ssh_session();
 822         packet_close();
 823
 824         if (options.control_path != NULL && muxserver_sock != -1)
 825                 unlink(options.control_path);
 826
 827         /*
 828          * Send SIGHUP to proxy command if used. We don't wait() in
 829          * case it hangs and instead rely on init to reap the child
 830          */
 831         if (proxy_command_pid > 1)
 832                 kill(proxy_command_pid, SIGHUP);
 833
 834         return exit_status;
 835 }
 836
 837 /* Callback for remote forward global requests */
 838 static void
 839 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 840 {
 841         Forward *rfwd = (Forward *)ctxt;
 842
 843         /* XXX verbose() on failure? */
 844         debug("remote forward %s for: listen %d, connect %s:%d",
 845             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
 846             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
 847         if (type == SSH2_MSG_REQUEST_SUCCESS && rfwd->listen_port == 0) {
 848                 logit("Allocated port %u for remote forward to %s:%d",
 849                         packet_get_int(),
 850                         rfwd->connect_host, rfwd->connect_port);
 851         }
 852
 853         if (type == SSH2_MSG_REQUEST_FAILURE) {
 854                 if (options.exit_on_forward_failure)
 855                         fatal("Error: remote port forwarding failed for "
 856                             "listen port %d", rfwd->listen_port);
 857                 else
 858                         logit("Warning: remote port forwarding failed for "
 859                             "listen port %d", rfwd->listen_port);
 860         }
 861         if (++remote_forward_confirms_received == options.num_remote_forwards) {
 862                 debug("All remote forwarding requests processed");
 863                 if (fork_after_authentication_flag) {
 864                         fork_after_authentication_flag = 0;
 865                         if (daemon(1, 1) < 0)
 866                                 fatal("daemon() failed: %.200s",
 867                                     strerror(errno));
 868                 }
 869         }
 870 }
 871
 872 static void
 873 ssh_init_forwarding(void)
 874 {
 875         int success = 0;
 876         int i;
 877
 878         /* Initiate local TCP/IP port forwardings. */
 879         for (i = 0; i < options.num_local_forwards; i++) {
 880                 debug("Local connections to %.200s:%d forwarded to remote "
 881                     "address %.200s:%d",
 882                     (options.local_forwards[i].listen_host == NULL) ?
 883                     (options.gateway_ports ? "*" : "LOCALHOST") :
 884                     options.local_forwards[i].listen_host,
 885                     options.local_forwards[i].listen_port,
 886                     options.local_forwards[i].connect_host,
 887                     options.local_forwards[i].connect_port);
 888                 success += channel_setup_local_fwd_listener(
 889                     options.local_forwards[i].listen_host,
 890                     options.local_forwards[i].listen_port,
 891                     options.local_forwards[i].connect_host,
 892                     options.local_forwards[i].connect_port,
 893                     options.gateway_ports);
 894         }
 895         if (i > 0 && success != i && options.exit_on_forward_failure)
 896                 fatal("Could not request local forwarding.");
 897         if (i > 0 && success == 0)
 898                 error("Could not request local forwarding.");
 899
 900         /* Initiate remote TCP/IP port forwardings. */
 901         for (i = 0; i < options.num_remote_forwards; i++) {
 902                 debug("Remote connections from %.200s:%d forwarded to "
 903                     "local address %.200s:%d",
 904                     (options.remote_forwards[i].listen_host == NULL) ?
 905                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 906                     options.remote_forwards[i].listen_port,
 907                     options.remote_forwards[i].connect_host,
 908                     options.remote_forwards[i].connect_port);
 909                 if (channel_request_remote_forwarding(
 910                     options.remote_forwards[i].listen_host,
 911                     options.remote_forwards[i].listen_port,
 912                     options.remote_forwards[i].connect_host,
 913                     options.remote_forwards[i].connect_port) < 0) {
 914                         if (options.exit_on_forward_failure)
 915                                 fatal("Could not request remote forwarding.");
 916                         else
 917                                 logit("Warning: Could not request remote "
 918                                     "forwarding.");
 919                 }
 920                 client_register_global_confirm(ssh_confirm_remote_forward,
 921                     &options.remote_forwards[i]);
 922         }
 923
 924         /* Initiate tunnel forwarding. */
 925         if (options.tun_open != SSH_TUNMODE_NO) {
 926                 if (client_request_tun_fwd(options.tun_open,
 927                     options.tun_local, options.tun_remote) == -1) {
 928                         if (options.exit_on_forward_failure)
 929                                 fatal("Could not request tunnel forwarding.");
 930                         else
 931                                 error("Could not request tunnel forwarding.");
 932                 }
 933         }
 934 }
 935
 936 static void
 937 check_agent_present(void)
 938 {
 939         if (options.forward_agent) {
 940                 /* Clear agent forwarding if we don't have an agent. */
 941                 if (!ssh_agent_present())
 942                         options.forward_agent = 0;
 943         }
 944 }
 945
 946 static int
 947 ssh_session(void)
 948 {
 949         int type;
 950         int interactive = 0;
 951         int have_tty = 0;
 952         struct winsize ws;
 953         char *cp;
 954         const char *display;
 955
 956         /* Enable compression if requested. */
 957         if (options.compression) {
 958                 debug("Requesting compression at level %d.",
 959                     options.compression_level);
 960
 961                 if (options.compression_level < 1 ||
 962                     options.compression_level > 9)
 963                         fatal("Compression level must be from 1 (fast) to "
 964                             "9 (slow, best).");
 965
 966                 /* Send the request. */
 967                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 968                 packet_put_int(options.compression_level);
 969                 packet_send();
 970                 packet_write_wait();
 971                 type = packet_read();
 972                 if (type == SSH_SMSG_SUCCESS)
 973                         packet_start_compression(options.compression_level);
 974                 else if (type == SSH_SMSG_FAILURE)
 975                         logit("Warning: Remote host refused compression.");
 976                 else
 977                         packet_disconnect("Protocol error waiting for "
 978                             "compression response.");
 979         }
 980         /* Allocate a pseudo tty if appropriate. */
 981         if (tty_flag) {
 982                 debug("Requesting pty.");
 983
 984                 /* Start the packet. */
 985                 packet_start(SSH_CMSG_REQUEST_PTY);
 986
 987                 /* Store TERM in the packet.  There is no limit on the
 988                    length of the string. */
 989                 cp = getenv("TERM");
 990                 if (!cp)
 991                         cp = "";
 992                 packet_put_cstring(cp);
 993
 994                 /* Store window size in the packet. */
 995                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 996                         memset(&ws, 0, sizeof(ws));
 997                 packet_put_int((u_int)ws.ws_row);
 998                 packet_put_int((u_int)ws.ws_col);
 999                 packet_put_int((u_int)ws.ws_xpixel);
1000                 packet_put_int((u_int)ws.ws_ypixel);
1001
1002                 /* Store tty modes in the packet. */
1003                 tty_make_modes(fileno(stdin), NULL);
1004
1005                 /* Send the packet, and wait for it to leave. */
1006                 packet_send();
1007                 packet_write_wait();
1008
1009                 /* Read response from the server. */
1010                 type = packet_read();
1011                 if (type == SSH_SMSG_SUCCESS) {
1012                         interactive = 1;
1013                         have_tty = 1;
1014                 } else if (type == SSH_SMSG_FAILURE)
1015                         logit("Warning: Remote host failed or refused to "
1016                             "allocate a pseudo tty.");
1017                 else
1018                         packet_disconnect("Protocol error waiting for pty "
1019                             "request response.");
1020         }
1021         /* Request X11 forwarding if enabled and DISPLAY is set. */
1022         display = getenv("DISPLAY");
1023         if (options.forward_x11 && display != NULL) {
1024                 char *proto, *data;
1025                 /* Get reasonable local authentication information. */
1026                 client_x11_get_proto(display, options.xauth_location,
1027                     options.forward_x11_trusted, &proto, &data);
1028                 /* Request forwarding with authentication spoofing. */
1029                 debug("Requesting X11 forwarding with authentication "
1030                     "spoofing.");
1031                 x11_request_forwarding_with_spoofing(0, display, proto, data);
1032
1033                 /* Read response from the server. */
1034                 type = packet_read();
1035                 if (type == SSH_SMSG_SUCCESS) {
1036                         interactive = 1;
1037                 } else if (type == SSH_SMSG_FAILURE) {
1038                         logit("Warning: Remote host denied X11 forwarding.");
1039                 } else {
1040                         packet_disconnect("Protocol error waiting for X11 "
1041                             "forwarding");
1042                 }
1043         }
1044         /* Tell the packet module whether this is an interactive session. */
1045         packet_set_interactive(interactive);
1046
1047         /* Request authentication agent forwarding if appropriate. */
1048         check_agent_present();
1049
1050         if (options.forward_agent) {
1051                 debug("Requesting authentication agent forwarding.");
1052                 auth_request_forwarding();
1053
1054                 /* Read response from the server. */
1055                 type = packet_read();
1056                 packet_check_eom();
1057                 if (type != SSH_SMSG_SUCCESS)
1058                         logit("Warning: Remote host denied authentication agent forwarding.");
1059         }
1060
1061         /* Initiate port forwardings. */
1062         ssh_init_forwarding();
1063
1064         /* Execute a local command */
1065         if (options.local_command != NULL &&
1066             options.permit_local_command)
1067                 ssh_local_cmd(options.local_command);
1068
1069         /*
1070          * If requested and we are not interested in replies to remote
1071          * forwarding requests, then let ssh continue in the background.
1072          */
1073         if (fork_after_authentication_flag &&
1074             (!options.exit_on_forward_failure ||
1075             options.num_remote_forwards == 0)) {
1076                 fork_after_authentication_flag = 0;
1077                 if (daemon(1, 1) < 0)
1078                         fatal("daemon() failed: %.200s", strerror(errno));
1079         }
1080
1081         /*
1082          * If a command was specified on the command line, execute the
1083          * command now. Otherwise request the server to start a shell.
1084          */
1085         if (buffer_len(&command) > 0) {
1086                 int len = buffer_len(&command);
1087                 if (len > 900)
1088                         len = 900;
1089                 debug("Sending command: %.*s", len,
1090                     (u_char *)buffer_ptr(&command));
1091                 packet_start(SSH_CMSG_EXEC_CMD);
1092                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1093                 packet_send();
1094                 packet_write_wait();
1095         } else {
1096                 debug("Requesting shell.");
1097                 packet_start(SSH_CMSG_EXEC_SHELL);
1098                 packet_send();
1099                 packet_write_wait();
1100         }
1101
1102         /* Enter the interactive session. */
1103         return client_loop(have_tty, tty_flag ?
1104             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1105 }
1106
1107 /* request pty/x11/agent/tcpfwd/shell for channel */
1108 static void
1109 ssh_session2_setup(int id, void *arg)
1110 {
1111         extern char **environ;
1112         const char *display;
1113         int interactive = tty_flag;
1114
1115         display = getenv("DISPLAY");
1116         if (options.forward_x11 && display != NULL) {
1117                 char *proto, *data;
1118                 /* Get reasonable local authentication information. */
1119                 client_x11_get_proto(display, options.xauth_location,
1120                     options.forward_x11_trusted, &proto, &data);
1121                 /* Request forwarding with authentication spoofing. */
1122                 debug("Requesting X11 forwarding with authentication "
1123                     "spoofing.");
1124                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1125                 interactive = 1;
1126                 /* XXX wait for reply */
1127         }
1128
1129         check_agent_present();
1130         if (options.forward_agent) {
1131                 debug("Requesting authentication agent forwarding.");
1132                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1133                 packet_send();
1134         }
1135
1136         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1137             NULL, fileno(stdin), &command, environ);
1138
1139         packet_set_interactive(interactive);
1140 }
1141
1142 /* open new channel for a session */
1143 static int
1144 ssh_session2_open(void)
1145 {
1146         Channel *c;
1147         int window, packetmax, in, out, err;
1148
1149         if (stdin_null_flag) {
1150                 in = open(_PATH_DEVNULL, O_RDONLY);
1151         } else {
1152                 in = dup(STDIN_FILENO);
1153         }
1154         out = dup(STDOUT_FILENO);
1155         err = dup(STDERR_FILENO);
1156
1157         if (in < 0 || out < 0 || err < 0)
1158                 fatal("dup() in/out/err failed");
1159
1160         /* enable nonblocking unless tty */
1161         if (!isatty(in))
1162                 set_nonblock(in);
1163         if (!isatty(out))
1164                 set_nonblock(out);
1165         if (!isatty(err))
1166                 set_nonblock(err);
1167
1168         window = CHAN_SES_WINDOW_DEFAULT;
1169         packetmax = CHAN_SES_PACKET_DEFAULT;
1170         if (tty_flag) {
1171                 window >>= 1;
1172                 packetmax >>= 1;
1173         }
1174         c = channel_new(
1175             "session", SSH_CHANNEL_OPENING, in, out, err,
1176             window, packetmax, CHAN_EXTENDED_WRITE,
1177             "client-session", /*nonblock*/0);
1178
1179         debug3("ssh_session2_open: channel_new: %d", c->self);
1180
1181         channel_send_open(c->self);
1182         if (!no_shell_flag)
1183                 channel_register_open_confirm(c->self,
1184                     ssh_session2_setup, NULL);
1185
1186         return c->self;
1187 }
1188
1189 static int
1190 ssh_session2(void)
1191 {
1192         int id = -1;
1193
1194         /* XXX should be pre-session */
1195         ssh_init_forwarding();
1196
1197         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1198                 id = ssh_session2_open();
1199
1200         /* If we don't expect to open a new session, then disallow it */
1201         if (options.control_master == SSHCTL_MASTER_NO &&
1202             (datafellows & SSH_NEW_OPENSSH)) {
1203                 debug("Requesting no-more-sessions@openssh.com");
1204                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1205                 packet_put_cstring("no-more-sessions@openssh.com");
1206                 packet_put_char(0);
1207                 packet_send();
1208         }
1209
1210         /* Execute a local command */
1211         if (options.local_command != NULL &&
1212             options.permit_local_command)
1213                 ssh_local_cmd(options.local_command);
1214
1215         /* Start listening for multiplex clients */
1216         muxserver_listen();
1217
1218         /* If requested, let ssh continue in the background. */
1219         if (fork_after_authentication_flag) {
1220                 fork_after_authentication_flag = 0;
1221                 if (daemon(1, 1) < 0)
1222                         fatal("daemon() failed: %.200s", strerror(errno));
1223         }
1224
1225         return client_loop(tty_flag, tty_flag ?
1226             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1227 }
1228
1229 static void
1230 load_public_identity_files(void)
1231 {
1232         char *filename, *cp, thishost[NI_MAXHOST];
1233         char *pwdir = NULL, *pwname = NULL;
1234         int i = 0;
1235         Key *public;
1236         struct passwd *pw;
1237 #ifdef SMARTCARD
1238         Key **keys;
1239
1240         if (options.smartcard_device != NULL &&
1241             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1242             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL) {
1243                 int count = 0;
1244                 for (i = 0; keys[i] != NULL; i++) {
1245                         count++;
1246                         memmove(&options.identity_files[1],
1247                             &options.identity_files[0],
1248                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1249                         memmove(&options.identity_keys[1],
1250                             &options.identity_keys[0],
1251                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1252                         options.num_identity_files++;
1253                         options.identity_keys[0] = keys[i];
1254                         options.identity_files[0] = sc_get_key_label(keys[i]);
1255                 }
1256                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1257                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1258                 i = count;
1259                 xfree(keys);
1260         }
1261 #endif /* SMARTCARD */
1262         if ((pw = getpwuid(original_real_uid)) == NULL)
1263                 fatal("load_public_identity_files: getpwuid failed");
1264         pwname = xstrdup(pw->pw_name);
1265         pwdir = xstrdup(pw->pw_dir);
1266         if (gethostname(thishost, sizeof(thishost)) == -1)
1267                 fatal("load_public_identity_files: gethostname: %s",
1268                     strerror(errno));
1269         for (; i < options.num_identity_files; i++) {
1270                 cp = tilde_expand_filename(options.identity_files[i],
1271                     original_real_uid);
1272                 filename = percent_expand(cp, "d", pwdir,
1273                     "u", pwname, "l", thishost, "h", host,
1274                     "r", options.user, (char *)NULL);
1275                 xfree(cp);
1276                 public = key_load_public(filename, NULL);
1277                 debug("identity file %s type %d", filename,
1278                     public ? public->type : -1);
1279                 xfree(options.identity_files[i]);
1280                 options.identity_files[i] = filename;
1281                 options.identity_keys[i] = public;
1282         }
1283         bzero(pwname, strlen(pwname));
1284         xfree(pwname);
1285         bzero(pwdir, strlen(pwdir));
1286         xfree(pwdir);
1287 }