openssh/ssh.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * Ssh client program.  This program can be used to log into a remote machine.
   6  * The software supports strong authentication, encryption, and forwarding
   7  * of X11, TCP/IP, and authentication connections.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  16  * Copyright (c) 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  17  *
  18  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  19  * in Canada (German citizen).
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43 RCSID("$OpenBSD: ssh.c,v 1.190 2003/02/06 09:27:29 markus Exp $");
  44
  45 #include <openssl/evp.h>
  46 #include <openssl/err.h>
  47
  48 #include "ssh.h"
  49 #include "ssh1.h"
  50 #include "ssh2.h"
  51 #include "compat.h"
  52 #include "cipher.h"
  53 #include "xmalloc.h"
  54 #include "packet.h"
  55 #include "buffer.h"
  56 #include "channels.h"
  57 #include "key.h"
  58 #include "authfd.h"
  59 #include "authfile.h"
  60 #include "pathnames.h"
  61 #include "clientloop.h"
  62 #include "log.h"
  63 #include "readconf.h"
  64 #include "sshconnect.h"
  65 #include "tildexpand.h"
  66 #include "dispatch.h"
  67 #include "misc.h"
  68 #include "kex.h"
  69 #include "mac.h"
  70 #include "sshtty.h"
  71
  72 #ifdef SMARTCARD
  73 #include "scard.h"
  74 #endif
  75
  76 #ifdef HAVE___PROGNAME
  77 extern char *__progname;
  78 #else
  79 char *__progname;
  80 #endif
  81
  82 /* Flag indicating whether IPv4 or IPv6.  This can be set on the command line.
  83    Default value is AF_UNSPEC means both IPv4 and IPv6. */
  84 #ifdef IPV4_DEFAULT
  85 int IPv4or6 = AF_INET;
  86 #else
  87 int IPv4or6 = AF_UNSPEC;
  88 #endif
  89
  90 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
  91 int debug_flag = 0;
  92
  93 /* Flag indicating whether a tty should be allocated */
  94 int tty_flag = 0;
  95 int no_tty_flag = 0;
  96 int force_tty_flag = 0;
  97
  98 /* don't exec a shell */
  99 int no_shell_flag = 0;
 100
 101 /*
 102  * Flag indicating that nothing should be read from stdin.  This can be set
 103  * on the command line.
 104  */
 105 int stdin_null_flag = 0;
 106
 107 /*
 108  * Flag indicating that ssh should fork after authentication.  This is useful
 109  * so that the passphrase can be entered manually, and then ssh goes to the
 110  * background.
 111  */
 112 int fork_after_authentication_flag = 0;
 113
 114 /*
 115  * General data structure for command line options and options configurable
 116  * in configuration files.  See readconf.h.
 117  */
 118 Options options;
 119
 120 /* optional user configfile */
 121 char *config = NULL;
 122
 123 /*
 124  * Name of the host we are connecting to.  This is the name given on the
 125  * command line, or the HostName specified for the user-supplied name in a
 126  * configuration file.
 127  */
 128 char *host;
 129
 130 /* socket address the host resolves to */
 131 struct sockaddr_storage hostaddr;
 132
 133 /* Private host keys. */
 134 Sensitive sensitive_data;
 135
 136 /* Original real UID. */
 137 uid_t original_real_uid;
 138 uid_t original_effective_uid;
 139
 140 /* command to be executed */
 141 Buffer command;
 142
 143 /* Should we execute a command or invoke a subsystem? */
 144 int subsystem_flag = 0;
 145
 146 /* # of replies received for global requests */
 147 static int client_global_request_id = 0;
 148
 149 /* pid of proxycommand child process */
 150 pid_t proxy_command_pid = 0;
 151
 152 /* Prints a help message to the user.  This function never returns. */
 153
 154 static void
 155 usage(void)
 156 {
 157         fprintf(stderr, "Usage: %s [options] host [command]\n", __progname);
 158         fprintf(stderr, "Options:\n");
 159         fprintf(stderr, "  -l user     Log in using this user name.\n");
 160         fprintf(stderr, "  -n          Redirect input from " _PATH_DEVNULL ".\n");
 161         fprintf(stderr, "  -F config   Config file (default: ~/%s).\n",
 162              _PATH_SSH_USER_CONFFILE);
 163         fprintf(stderr, "  -A          Enable authentication agent forwarding.\n");
 164         fprintf(stderr, "  -a          Disable authentication agent forwarding (default).\n");
 165 #ifdef AFS
 166         fprintf(stderr, "  -k          Disable Kerberos ticket and AFS token forwarding.\n");
 167 #endif                          /* AFS */
 168         fprintf(stderr, "  -X          Enable X11 connection forwarding.\n");
 169         fprintf(stderr, "  -x          Disable X11 connection forwarding (default).\n");
 170         fprintf(stderr, "  -i file     Identity for public key authentication "
 171             "(default: ~/.ssh/identity)\n");
 172 #ifdef SMARTCARD
 173         fprintf(stderr, "  -I reader   Set smartcard reader.\n");
 174 #endif
 175         fprintf(stderr, "  -t          Tty; allocate a tty even if command is given.\n");
 176         fprintf(stderr, "  -T          Do not allocate a tty.\n");
 177         fprintf(stderr, "  -v          Verbose; display verbose debugging messages.\n");
 178         fprintf(stderr, "              Multiple -v increases verbosity.\n");
 179         fprintf(stderr, "  -V          Display version number only.\n");
 180         fprintf(stderr, "  -q          Quiet; don't display any warning messages.\n");
 181         fprintf(stderr, "  -f          Fork into background after authentication.\n");
 182         fprintf(stderr, "  -e char     Set escape character; ``none'' = disable (default: ~).\n");
 183
 184         fprintf(stderr, "  -c cipher   Select encryption algorithm\n");
 185         fprintf(stderr, "  -m macs     Specify MAC algorithms for protocol version 2.\n");
 186         fprintf(stderr, "  -p port     Connect to this port.  Server must be on the same port.\n");
 187         fprintf(stderr, "  -L listen-port:host:port   Forward local port to remote address\n");
 188         fprintf(stderr, "  -R listen-port:host:port   Forward remote port to local address\n");
 189         fprintf(stderr, "              These cause %s to listen for connections on a port, and\n", __progname);
 190         fprintf(stderr, "              forward them to the other side by connecting to host:port.\n");
 191         fprintf(stderr, "  -D port     Enable dynamic application-level port forwarding.\n");
 192         fprintf(stderr, "  -C          Enable compression.\n");
 193         fprintf(stderr, "  -N          Do not execute a shell or command.\n");
 194         fprintf(stderr, "  -g          Allow remote hosts to connect to forwarded ports.\n");
 195         fprintf(stderr, "  -1          Force protocol version 1.\n");
 196         fprintf(stderr, "  -2          Force protocol version 2.\n");
 197         fprintf(stderr, "  -4          Use IPv4 only.\n");
 198         fprintf(stderr, "  -6          Use IPv6 only.\n");
 199         fprintf(stderr, "  -o 'option' Process the option as if it was read from a configuration file.\n");
 200         fprintf(stderr, "  -s          Invoke command (mandatory) as SSH2 subsystem.\n");
 201         fprintf(stderr, "  -b addr     Local IP address.\n");
 202         exit(1);
 203 }
 204
 205 static int ssh_session(void);
 206 static int ssh_session2(void);
 207 static void load_public_identity_files(void);
 208
 209 /*
 210  * Main program for the ssh client.
 211  */
 212 int
 213 main(int ac, char **av)
 214 {
 215         int i, opt, exit_status;
 216         u_short fwd_port, fwd_host_port;
 217         char sfwd_port[6], sfwd_host_port[6];
 218         char *p, *cp, buf[256];
 219         struct stat st;
 220         struct passwd *pw;
 221         int dummy;
 222         extern int optind, optreset;
 223         extern char *optarg;
 224
 225         __progname = get_progname(av[0]);
 226         init_pathnames();
 227         init_rng();
 228
 229         /*
 230          * Save the original real uid.  It will be needed later (uid-swapping
 231          * may clobber the real uid).
 232          */
 233         original_real_uid = getuid();
 234         original_effective_uid = geteuid();
 235
 236         /*
 237          * Use uid-swapping to give up root privileges for the duration of
 238          * option processing.  We will re-instantiate the rights when we are
 239          * ready to create the privileged port, and will permanently drop
 240          * them when the port has been created (actually, when the connection
 241          * has been made, as we may need to create the port several times).
 242          */
 243         PRIV_END;
 244
 245 #ifdef HAVE_SETRLIMIT
 246         /* If we are installed setuid root be careful to not drop core. */
 247         if (original_real_uid != original_effective_uid) {
 248                 struct rlimit rlim;
 249                 rlim.rlim_cur = rlim.rlim_max = 0;
 250                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 251                         fatal("setrlimit failed: %.100s", strerror(errno));
 252         }
 253 #endif
 254         /* Get user data. */
 255         pw = getpwuid(original_real_uid);
 256         if (!pw) {
 257                 log("You don't exist, go away!");
 258                 exit(1);
 259         }
 260         /* Take a copy of the returned structure. */
 261         pw = pwcopy(pw);
 262
 263         /*
 264          * Set our umask to something reasonable, as some files are created
 265          * with the default umask.  This will make them world-readable but
 266          * writable only by the owner, which is ok for all files for which we
 267          * don't set the modes explicitly.
 268          */
 269         umask(022);
 270
 271         /* Initialize option structure to indicate that no values have been set. */
 272         initialize_options(&options);
 273
 274         /* Parse command-line arguments. */
 275         host = NULL;
 276
 277 again:
 278         while ((opt = getopt(ac, av,
 279             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVX")) != -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                         IPv4or6 = AF_INET;
 289                         break;
 290                 case '6':
 291                         IPv4or6 = 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 'g':
 307                         options.gateway_ports = 1;
 308                         break;
 309                 case 'P':       /* deprecated */
 310                         options.use_privileged_port = 0;
 311                         break;
 312                 case 'a':
 313                         options.forward_agent = 0;
 314                         break;
 315                 case 'A':
 316                         options.forward_agent = 1;
 317                         break;
 318 #ifdef AFS
 319                 case 'k':
 320                         options.kerberos_tgt_passing = 0;
 321                         options.afs_token_passing = 0;
 322                         break;
 323 #endif
 324                 case 'i':
 325                         if (stat(optarg, &st) < 0) {
 326                                 fprintf(stderr, "Warning: Identity file %s "
 327                                     "does not exist.\n", optarg);
 328                                 break;
 329                         }
 330                         if (options.num_identity_files >=
 331                             SSH_MAX_IDENTITY_FILES)
 332                                 fatal("Too many identity files specified "
 333                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 334                         options.identity_files[options.num_identity_files++] =
 335                             xstrdup(optarg);
 336                         break;
 337                 case 'I':
 338 #ifdef SMARTCARD
 339                         options.smartcard_device = xstrdup(optarg);
 340 #else
 341                         fprintf(stderr, "no support for smartcards.\n");
 342 #endif
 343                         break;
 344                 case 't':
 345                         if (tty_flag)
 346                                 force_tty_flag = 1;
 347                         tty_flag = 1;
 348                         break;
 349                 case 'v':
 350                         if (0 == debug_flag) {
 351                                 debug_flag = 1;
 352                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 353                         } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
 354                                 options.log_level++;
 355                                 break;
 356                         } else
 357                                 fatal("Too high debugging level.");
 358                         /* fallthrough */
 359                 case 'V':
 360                         fprintf(stderr,
 361                             "%s, SSH protocols %d.%d/%d.%d, OpenSSL 0x%8.8lx\n",
 362                             SSH_VERSION,
 363                             PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
 364                             PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
 365                             SSLeay());
 366                         if (opt == 'V')
 367                                 exit(0);
 368                         break;
 369                 case 'q':
 370                         options.log_level = SYSLOG_LEVEL_QUIET;
 371                         break;
 372                 case 'e':
 373                         if (optarg[0] == '^' && optarg[2] == 0 &&
 374                             (u_char) optarg[1] >= 64 &&
 375                             (u_char) optarg[1] < 128)
 376                                 options.escape_char = (u_char) optarg[1] & 31;
 377                         else if (strlen(optarg) == 1)
 378                                 options.escape_char = (u_char) optarg[0];
 379                         else if (strcmp(optarg, "none") == 0)
 380                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 381                         else {
 382                                 fprintf(stderr, "Bad escape character '%s'.\n",
 383                                     optarg);
 384                                 exit(1);
 385                         }
 386                         break;
 387                 case 'c':
 388                         if (ciphers_valid(optarg)) {
 389                                 /* SSH2 only */
 390                                 options.ciphers = xstrdup(optarg);
 391                                 options.cipher = SSH_CIPHER_ILLEGAL;
 392                         } else {
 393                                 /* SSH1 only */
 394                                 options.cipher = cipher_number(optarg);
 395                                 if (options.cipher == -1) {
 396                                         fprintf(stderr,
 397                                             "Unknown cipher type '%s'\n",
 398                                             optarg);
 399                                         exit(1);
 400                                 }
 401                                 if (options.cipher == SSH_CIPHER_3DES)
 402                                         options.ciphers = "3des-cbc";
 403                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 404                                         options.ciphers = "blowfish-cbc";
 405                                 else
 406                                         options.ciphers = (char *)-1;
 407                         }
 408                         break;
 409                 case 'm':
 410                         if (mac_valid(optarg))
 411                                 options.macs = xstrdup(optarg);
 412                         else {
 413                                 fprintf(stderr, "Unknown mac type '%s'\n",
 414                                     optarg);
 415                                 exit(1);
 416                         }
 417                         break;
 418                 case 'p':
 419                         options.port = a2port(optarg);
 420                         if (options.port == 0) {
 421                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 422                                 exit(1);
 423                         }
 424                         break;
 425                 case 'l':
 426                         options.user = optarg;
 427                         break;
 428
 429                 case 'L':
 430                 case 'R':
 431                         if (sscanf(optarg, "%5[0-9]:%255[^:]:%5[0-9]",
 432                             sfwd_port, buf, sfwd_host_port) != 3 &&
 433                             sscanf(optarg, "%5[0-9]/%255[^/]/%5[0-9]",
 434                             sfwd_port, buf, sfwd_host_port) != 3) {
 435                                 fprintf(stderr,
 436                                     "Bad forwarding specification '%s'\n",
 437                                     optarg);
 438                                 usage();
 439                                 /* NOTREACHED */
 440                         }
 441                         if ((fwd_port = a2port(sfwd_port)) == 0 ||
 442                             (fwd_host_port = a2port(sfwd_host_port)) == 0) {
 443                                 fprintf(stderr,
 444                                     "Bad forwarding port(s) '%s'\n", optarg);
 445                                 exit(1);
 446                         }
 447                         if (opt == 'L')
 448                                 add_local_forward(&options, fwd_port, buf,
 449                                     fwd_host_port);
 450                         else if (opt == 'R')
 451                                 add_remote_forward(&options, fwd_port, buf,
 452                                     fwd_host_port);
 453                         break;
 454
 455                 case 'D':
 456                         fwd_port = a2port(optarg);
 457                         if (fwd_port == 0) {
 458                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 459                                     optarg);
 460                                 exit(1);
 461                         }
 462                         add_local_forward(&options, fwd_port, "socks4", 0);
 463                         break;
 464
 465                 case 'C':
 466                         options.compression = 1;
 467                         break;
 468                 case 'N':
 469                         no_shell_flag = 1;
 470                         no_tty_flag = 1;
 471                         break;
 472                 case 'T':
 473                         no_tty_flag = 1;
 474                         break;
 475                 case 'o':
 476                         dummy = 1;
 477                         if (process_config_line(&options, host ? host : "",
 478                             optarg, "command-line", 0, &dummy) != 0)
 479                                 exit(1);
 480                         break;
 481                 case 's':
 482                         subsystem_flag = 1;
 483                         break;
 484                 case 'b':
 485                         options.bind_address = optarg;
 486                         break;
 487                 case 'F':
 488                         config = optarg;
 489                         break;
 490                 default:
 491                         usage();
 492                 }
 493         }
 494
 495         ac -= optind;
 496         av += optind;
 497
 498         if (ac > 0 && !host && **av != '-') {
 499                 if (strrchr(*av, '@')) {
 500                         p = xstrdup(*av);
 501                         cp = strrchr(p, '@');
 502                         if (cp == NULL || cp == p)
 503                                 usage();
 504                         options.user = p;
 505                         *cp = '\0';
 506                         host = ++cp;
 507                 } else
 508                         host = *av;
 509                 if (ac > 1) {
 510                         optind = optreset = 1;
 511                         goto again;
 512                 }
 513                 ac--, av++;
 514         }
 515
 516         /* Check that we got a host name. */
 517         if (!host)
 518                 usage();
 519
 520         SSLeay_add_all_algorithms();
 521         ERR_load_crypto_strings();
 522         channel_set_af(IPv4or6);
 523
 524         /* Initialize the command to execute on remote host. */
 525         buffer_init(&command);
 526
 527         /*
 528          * Save the command to execute on the remote host in a buffer. There
 529          * is no limit on the length of the command, except by the maximum
 530          * packet size.  Also sets the tty flag if there is no command.
 531          */
 532         if (!ac) {
 533                 /* No command specified - execute shell on a tty. */
 534                 tty_flag = 1;
 535                 if (subsystem_flag) {
 536                         fprintf(stderr,
 537                             "You must specify a subsystem to invoke.\n");
 538                         usage();
 539                 }
 540         } else {
 541                 /* A command has been specified.  Store it into the buffer. */
 542                 for (i = 0; i < ac; i++) {
 543                         if (i)
 544                                 buffer_append(&command, " ", 1);
 545                         buffer_append(&command, av[i], strlen(av[i]));
 546                 }
 547         }
 548
 549         /* Cannot fork to background if no command. */
 550         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 551                 fatal("Cannot fork into background without a command to execute.");
 552
 553         /* Allocate a tty by default if no command specified. */
 554         if (buffer_len(&command) == 0)
 555                 tty_flag = 1;
 556
 557         /* Force no tty */
 558         if (no_tty_flag)
 559                 tty_flag = 0;
 560         /* Do not allocate a tty if stdin is not a tty. */
 561         if (!isatty(fileno(stdin)) && !force_tty_flag) {
 562                 if (tty_flag)
 563                         log("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 564                 tty_flag = 0;
 565         }
 566
 567         /*
 568          * Initialize "log" output.  Since we are the client all output
 569          * actually goes to stderr.
 570          */
 571         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 572             SYSLOG_FACILITY_USER, 1);
 573
 574         /*
 575          * Read per-user configuration file.  Ignore the system wide config
 576          * file if the user specifies a config file on the command line.
 577          */
 578         if (config != NULL) {
 579                 if (!read_config_file(config, host, &options))
 580                         fatal("Can't open user config file %.100s: "
 581                             "%.100s", config, strerror(errno));
 582         } else  {
 583             /*
 584              * Since the config file parsing code aborts if it sees
 585              * options it doesn't recognize, allow users to put
 586              * options specific to compile-time add-ons in alternate
 587              * config files so their primary config file will
 588              * interoperate SSH versions that don't support those
 589              * options.
 590              */
 591 #ifdef GSSAPI
 592                 snprintf(buf, sizeof buf, "%.100s/%.100s.gssapi", pw->pw_dir,
 593                     _PATH_SSH_USER_CONFFILE);
 594                 (void)read_config_file(buf, host, &options);
 595 #ifdef GSI
 596                 snprintf(buf, sizeof buf, "%.100s/%.100s.gsi", pw->pw_dir,
 597                     _PATH_SSH_USER_CONFFILE);
 598                 (void)read_config_file(buf, host, &options);
 599 #endif
 600 #if defined(KRB4) || defined(KRB5)
 601                 snprintf(buf, sizeof buf, "%.100s/%.100s.krb", pw->pw_dir,
 602                     _PATH_SSH_USER_CONFFILE);
 603                 (void)read_config_file(buf, host, &options);
 604 #endif
 605 #ifdef AFS
 606                 snprintf(buf, sizeof buf, "%.100s/%.100s.afs", pw->pw_dir,
 607                     _PATH_SSH_USER_CONFFILE);
 608                 (void)read_config_file(buf, host, &options);
 609 #endif
 610 #endif
 611                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 612                     _PATH_SSH_USER_CONFFILE);
 613                 (void)read_config_file(buf, host, &options);
 614
 615                 /* Read systemwide configuration file after use config. */
 616                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
 617         }
 618
 619         /* Fill configuration defaults. */
 620         fill_default_options(&options);
 621
 622         /* reinit */
 623         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 624
 625         seed_rng();
 626
 627         if (options.user == NULL) {
 628                 options.user = xstrdup(pw->pw_name);
 629                 options.implicit = 1;
 630         }
 631         else options.implicit = 0;
 632
 633         if (options.hostname != NULL)
 634                 host = options.hostname;
 635
 636         if (options.proxy_command != NULL &&
 637             strcmp(options.proxy_command, "none") == 0)
 638                 options.proxy_command = NULL;
 639
 640         /* Disable rhosts authentication if not running as root. */
 641 #ifdef HAVE_CYGWIN
 642         /* Ignore uid if running under Windows */
 643         if (!options.use_privileged_port) {
 644 #else
 645         if (original_effective_uid != 0 || !options.use_privileged_port) {
 646 #endif
 647                 debug("Rhosts Authentication disabled, "
 648                     "originating port will not be trusted.");
 649                 options.rhosts_authentication = 0;
 650         }
 651         /* Open a connection to the remote host. */
 652
 653         if (ssh_connect(host, &hostaddr, options.port, IPv4or6,
 654             options.connection_attempts,
 655 #ifdef HAVE_CYGWIN
 656             options.use_privileged_port,
 657 #else
 658             original_effective_uid == 0 && options.use_privileged_port,
 659 #endif
 660             options.proxy_command) != 0)
 661                 exit(1);
 662
 663         /*
 664          * If we successfully made the connection, load the host private key
 665          * in case we will need it later for combined rsa-rhosts
 666          * authentication. This must be done before releasing extra
 667          * privileges, because the file is only readable by root.
 668          * If we cannot access the private keys, load the public keys
 669          * instead and try to execute the ssh-keysign helper instead.
 670          */
 671         sensitive_data.nkeys = 0;
 672         sensitive_data.keys = NULL;
 673         sensitive_data.external_keysign = 0;
 674         if (options.rhosts_rsa_authentication ||
 675             options.hostbased_authentication) {
 676                 sensitive_data.nkeys = 3;
 677                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 678                     sizeof(Key));
 679
 680                 PRIV_START;
 681                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 682                     _PATH_HOST_KEY_FILE, "", NULL);
 683                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 684                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 685                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 686                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 687                 PRIV_END;
 688
 689                 if (options.hostbased_authentication == 1 &&
 690                     sensitive_data.keys[0] == NULL &&
 691                     sensitive_data.keys[1] == NULL &&
 692                     sensitive_data.keys[2] == NULL) {
 693                         sensitive_data.keys[1] = key_load_public(
 694                             _PATH_HOST_DSA_KEY_FILE, NULL);
 695                         sensitive_data.keys[2] = key_load_public(
 696                             _PATH_HOST_RSA_KEY_FILE, NULL);
 697                         sensitive_data.external_keysign = 1;
 698                 }
 699         }
 700         /*
 701          * Get rid of any extra privileges that we may have.  We will no
 702          * longer need them.  Also, extra privileges could make it very hard
 703          * to read identity files and other non-world-readable files from the
 704          * user's home directory if it happens to be on a NFS volume where
 705          * root is mapped to nobody.
 706          */
 707         seteuid(original_real_uid);
 708         setuid(original_real_uid);
 709
 710         /*
 711          * Now that we are back to our own permissions, create ~/.ssh
 712          * directory if it doesn\'t already exist.
 713          */
 714         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 715         if (stat(buf, &st) < 0)
 716                 if (mkdir(buf, 0700) < 0)
 717                         error("Could not create directory '%.200s'.", buf);
 718
 719         /* load options.identity_files */
 720         load_public_identity_files();
 721
 722         /* Expand ~ in known host file names. */
 723         /* XXX mem-leaks: */
 724         options.system_hostfile =
 725             tilde_expand_filename(options.system_hostfile, original_real_uid);
 726         options.user_hostfile =
 727             tilde_expand_filename(options.user_hostfile, original_real_uid);
 728         options.system_hostfile2 =
 729             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 730         options.user_hostfile2 =
 731             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 732
 733         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 734
 735         /* Log into the remote system.  This never returns if the login fails. */
 736         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 737
 738         /* We no longer need the private host keys.  Clear them now. */
 739         if (sensitive_data.nkeys != 0) {
 740                 for (i = 0; i < sensitive_data.nkeys; i++) {
 741                         if (sensitive_data.keys[i] != NULL) {
 742                                 /* Destroys contents safely */
 743                                 debug3("clear hostkey %d", i);
 744                                 key_free(sensitive_data.keys[i]);
 745                                 sensitive_data.keys[i] = NULL;
 746                         }
 747                 }
 748                 xfree(sensitive_data.keys);
 749         }
 750         for (i = 0; i < options.num_identity_files; i++) {
 751                 if (options.identity_files[i]) {
 752                         xfree(options.identity_files[i]);
 753                         options.identity_files[i] = NULL;
 754                 }
 755                 if (options.identity_keys[i]) {
 756                         key_free(options.identity_keys[i]);
 757                         options.identity_keys[i] = NULL;
 758                 }
 759         }
 760
 761         exit_status = compat20 ? ssh_session2() : ssh_session();
 762         packet_close();
 763
 764         /*
 765          * Send SIGHUP to proxy command if used. We don't wait() in
 766          * case it hangs and instead rely on init to reap the child
 767          */
 768         if (proxy_command_pid > 1)
 769                 kill(proxy_command_pid, SIGHUP);
 770
 771         return exit_status;
 772 }
 773
 774 static void
 775 x11_get_proto(char **_proto, char **_data)
 776 {
 777         char line[512];
 778         static char proto[512], data[512];
 779         FILE *f;
 780         int got_data = 0, i;
 781         char *display;
 782         struct stat st;
 783
 784         *_proto = proto;
 785         *_data = data;
 786         proto[0] = data[0] = '\0';
 787         if (!options.xauth_location ||
 788             (stat(options.xauth_location, &st) == -1)) {
 789                 debug("No xauth program.");
 790         } else {
 791                 if ((display = getenv("DISPLAY")) == NULL) {
 792                         debug("x11_get_proto: DISPLAY not set");
 793                         return;
 794                 }
 795                 /* Try to get Xauthority information for the display. */
 796                 if (strncmp(display, "localhost:", 10) == 0)
 797                         /*
 798                          * Handle FamilyLocal case where $DISPLAY does
 799                          * not match an authorization entry.  For this we
 800                          * just try "xauth list unix:displaynum.screennum".
 801                          * XXX: "localhost" match to determine FamilyLocal
 802                          *      is not perfect.
 803                          */
 804                         snprintf(line, sizeof line, "%s list unix:%s 2>"
 805                             _PATH_DEVNULL, options.xauth_location, display+10);
 806                 else
 807                         snprintf(line, sizeof line, "%s list %.200s 2>"
 808                             _PATH_DEVNULL, options.xauth_location, display);
 809                 debug2("x11_get_proto: %s", line);
 810                 f = popen(line, "r");
 811                 if (f && fgets(line, sizeof(line), f) &&
 812                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 813                         got_data = 1;
 814                 if (f)
 815                         pclose(f);
 816         }
 817         /*
 818          * If we didn't get authentication data, just make up some
 819          * data.  The forwarding code will check the validity of the
 820          * response anyway, and substitute this data.  The X11
 821          * server, however, will ignore this fake data and use
 822          * whatever authentication mechanisms it was using otherwise
 823          * for the local connection.
 824          */
 825         if (!got_data) {
 826                 u_int32_t rand = 0;
 827
 828                 log("Warning: No xauth data; using fake authentication data for X11 forwarding.");
 829                 strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
 830                 for (i = 0; i < 16; i++) {
 831                         if (i % 4 == 0)
 832                                 rand = arc4random();
 833                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
 834                         rand >>= 8;
 835                 }
 836         }
 837 }
 838
 839 static void
 840 ssh_init_forwarding(void)
 841 {
 842         int success = 0;
 843         int i;
 844
 845         /* Initiate local TCP/IP port forwardings. */
 846         for (i = 0; i < options.num_local_forwards; i++) {
 847                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
 848                     options.local_forwards[i].port,
 849                     options.local_forwards[i].host,
 850                     options.local_forwards[i].host_port);
 851                 success += channel_setup_local_fwd_listener(
 852                     options.local_forwards[i].port,
 853                     options.local_forwards[i].host,
 854                     options.local_forwards[i].host_port,
 855                     options.gateway_ports);
 856         }
 857         if (i > 0 && success == 0)
 858                 error("Could not request local forwarding.");
 859
 860         /* Initiate remote TCP/IP port forwardings. */
 861         for (i = 0; i < options.num_remote_forwards; i++) {
 862                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
 863                     options.remote_forwards[i].port,
 864                     options.remote_forwards[i].host,
 865                     options.remote_forwards[i].host_port);
 866                 channel_request_remote_forwarding(
 867                     options.remote_forwards[i].port,
 868                     options.remote_forwards[i].host,
 869                     options.remote_forwards[i].host_port);
 870         }
 871 }
 872
 873 static void
 874 check_agent_present(void)
 875 {
 876         if (options.forward_agent) {
 877                 /* Clear agent forwarding if we don\'t have an agent. */
 878                 if (!ssh_agent_present())
 879                         options.forward_agent = 0;
 880         }
 881 }
 882
 883 static int
 884 ssh_session(void)
 885 {
 886         int type;
 887         int interactive = 0;
 888         int have_tty = 0;
 889         struct winsize ws;
 890         char *cp;
 891
 892         /* Enable compression if requested. */
 893         if (options.compression) {
 894                 debug("Requesting compression at level %d.", options.compression_level);
 895
 896                 if (options.compression_level < 1 || options.compression_level > 9)
 897                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 898
 899                 /* Send the request. */
 900                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 901                 packet_put_int(options.compression_level);
 902                 packet_send();
 903                 packet_write_wait();
 904                 type = packet_read();
 905                 if (type == SSH_SMSG_SUCCESS)
 906                         packet_start_compression(options.compression_level);
 907                 else if (type == SSH_SMSG_FAILURE)
 908                         log("Warning: Remote host refused compression.");
 909                 else
 910                         packet_disconnect("Protocol error waiting for compression response.");
 911         }
 912         /* Allocate a pseudo tty if appropriate. */
 913         if (tty_flag) {
 914                 debug("Requesting pty.");
 915
 916                 /* Start the packet. */
 917                 packet_start(SSH_CMSG_REQUEST_PTY);
 918
 919                 /* Store TERM in the packet.  There is no limit on the
 920                    length of the string. */
 921                 cp = getenv("TERM");
 922                 if (!cp)
 923                         cp = "";
 924                 packet_put_cstring(cp);
 925
 926                 /* Store window size in the packet. */
 927                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 928                         memset(&ws, 0, sizeof(ws));
 929                 packet_put_int(ws.ws_row);
 930                 packet_put_int(ws.ws_col);
 931                 packet_put_int(ws.ws_xpixel);
 932                 packet_put_int(ws.ws_ypixel);
 933
 934                 /* Store tty modes in the packet. */
 935                 tty_make_modes(fileno(stdin), NULL);
 936
 937                 /* Send the packet, and wait for it to leave. */
 938                 packet_send();
 939                 packet_write_wait();
 940
 941                 /* Read response from the server. */
 942                 type = packet_read();
 943                 if (type == SSH_SMSG_SUCCESS) {
 944                         interactive = 1;
 945                         have_tty = 1;
 946                 } else if (type == SSH_SMSG_FAILURE)
 947                         log("Warning: Remote host failed or refused to allocate a pseudo tty.");
 948                 else
 949                         packet_disconnect("Protocol error waiting for pty request response.");
 950         }
 951         /* Request X11 forwarding if enabled and DISPLAY is set. */
 952         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 953                 char *proto, *data;
 954                 /* Get reasonable local authentication information. */
 955                 x11_get_proto(&proto, &data);
 956                 /* Request forwarding with authentication spoofing. */
 957                 debug("Requesting X11 forwarding with authentication spoofing.");
 958                 x11_request_forwarding_with_spoofing(0, proto, data);
 959
 960                 /* Read response from the server. */
 961                 type = packet_read();
 962                 if (type == SSH_SMSG_SUCCESS) {
 963                         interactive = 1;
 964                 } else if (type == SSH_SMSG_FAILURE) {
 965                         log("Warning: Remote host denied X11 forwarding.");
 966                 } else {
 967                         packet_disconnect("Protocol error waiting for X11 forwarding");
 968                 }
 969         }
 970         /* Tell the packet module whether this is an interactive session. */
 971         packet_set_interactive(interactive);
 972
 973         /* Request authentication agent forwarding if appropriate. */
 974         check_agent_present();
 975
 976         if (options.forward_agent) {
 977                 debug("Requesting authentication agent forwarding.");
 978                 auth_request_forwarding();
 979
 980                 /* Read response from the server. */
 981                 type = packet_read();
 982                 packet_check_eom();
 983                 if (type != SSH_SMSG_SUCCESS)
 984                         log("Warning: Remote host denied authentication agent forwarding.");
 985         }
 986
 987         /* Initiate port forwardings. */
 988         ssh_init_forwarding();
 989
 990         /* If requested, let ssh continue in the background. */
 991         if (fork_after_authentication_flag)
 992                 if (daemon(1, 1) < 0)
 993                         fatal("daemon() failed: %.200s", strerror(errno));
 994
 995         /*
 996          * If a command was specified on the command line, execute the
 997          * command now. Otherwise request the server to start a shell.
 998          */
 999         if (buffer_len(&command) > 0) {
1000                 int len = buffer_len(&command);
1001                 if (len > 900)
1002                         len = 900;
1003                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1004                 packet_start(SSH_CMSG_EXEC_CMD);
1005                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1006                 packet_send();
1007                 packet_write_wait();
1008         } else {
1009                 debug("Requesting shell.");
1010                 packet_start(SSH_CMSG_EXEC_SHELL);
1011                 packet_send();
1012                 packet_write_wait();
1013         }
1014
1015         /* Enter the interactive session. */
1016         return client_loop(have_tty, tty_flag ?
1017             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1018 }
1019
1020 static void
1021 client_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1022 {
1023         int id, len;
1024
1025         id = packet_get_int();
1026         len = buffer_len(&command);
1027         if (len > 900)
1028                 len = 900;
1029         packet_check_eom();
1030         if (type == SSH2_MSG_CHANNEL_FAILURE)
1031                 fatal("Request for subsystem '%.*s' failed on channel %d",
1032                     len, (u_char *)buffer_ptr(&command), id);
1033 }
1034
1035 void
1036 client_global_request_reply(int type, u_int32_t seq, void *ctxt)
1037 {
1038         int i;
1039
1040         i = client_global_request_id++;
1041         if (i >= options.num_remote_forwards) {
1042                 debug("client_global_request_reply: too many replies %d > %d",
1043                     i, options.num_remote_forwards);
1044                 return;
1045         }
1046         debug("remote forward %s for: listen %d, connect %s:%d",
1047             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1048             options.remote_forwards[i].port,
1049             options.remote_forwards[i].host,
1050             options.remote_forwards[i].host_port);
1051         if (type == SSH2_MSG_REQUEST_FAILURE)
1052                 log("Warning: remote port forwarding failed for listen port %d",
1053                     options.remote_forwards[i].port);
1054 }
1055
1056 /* request pty/x11/agent/tcpfwd/shell for channel */
1057 static void
1058 ssh_session2_setup(int id, void *arg)
1059 {
1060         int len;
1061         int interactive = 0;
1062         struct termios tio;
1063
1064         debug2("ssh_session2_setup: id %d", id);
1065
1066         if (tty_flag) {
1067                 struct winsize ws;
1068                 char *cp;
1069                 cp = getenv("TERM");
1070                 if (!cp)
1071                         cp = "";
1072                 /* Store window size in the packet. */
1073                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1074                         memset(&ws, 0, sizeof(ws));
1075
1076                 channel_request_start(id, "pty-req", 0);
1077                 packet_put_cstring(cp);
1078                 packet_put_int(ws.ws_col);
1079                 packet_put_int(ws.ws_row);
1080                 packet_put_int(ws.ws_xpixel);
1081                 packet_put_int(ws.ws_ypixel);
1082                 tio = get_saved_tio();
1083                 tty_make_modes(/*ignored*/ 0, &tio);
1084                 packet_send();
1085                 interactive = 1;
1086                 /* XXX wait for reply */
1087         }
1088         if (options.forward_x11 &&
1089             getenv("DISPLAY") != NULL) {
1090                 char *proto, *data;
1091                 /* Get reasonable local authentication information. */
1092                 x11_get_proto(&proto, &data);
1093                 /* Request forwarding with authentication spoofing. */
1094                 debug("Requesting X11 forwarding with authentication spoofing.");
1095                 x11_request_forwarding_with_spoofing(id, proto, data);
1096                 interactive = 1;
1097                 /* XXX wait for reply */
1098         }
1099
1100         check_agent_present();
1101         if (options.forward_agent) {
1102                 debug("Requesting authentication agent forwarding.");
1103                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1104                 packet_send();
1105         }
1106
1107         len = buffer_len(&command);
1108         if (len > 0) {
1109                 if (len > 900)
1110                         len = 900;
1111                 if (subsystem_flag) {
1112                         debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command));
1113                         channel_request_start(id, "subsystem", /*want reply*/ 1);
1114                         /* register callback for reply */
1115                         /* XXX we assume that client_loop has already been called */
1116                         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
1117                         dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1118                 } else {
1119                         debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1120                         channel_request_start(id, "exec", 0);
1121                 }
1122                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1123                 packet_send();
1124         } else {
1125                 channel_request_start(id, "shell", 0);
1126                 packet_send();
1127         }
1128
1129         packet_set_interactive(interactive);
1130 }
1131
1132 /* open new channel for a session */
1133 static int
1134 ssh_session2_open(void)
1135 {
1136         Channel *c;
1137         int window, packetmax, in, out, err;
1138
1139         if (stdin_null_flag) {
1140                 in = open(_PATH_DEVNULL, O_RDONLY);
1141         } else {
1142                 in = dup(STDIN_FILENO);
1143         }
1144         out = dup(STDOUT_FILENO);
1145         err = dup(STDERR_FILENO);
1146
1147         if (in < 0 || out < 0 || err < 0)
1148                 fatal("dup() in/out/err failed");
1149
1150         /* enable nonblocking unless tty */
1151         if (!isatty(in))
1152                 set_nonblock(in);
1153         if (!isatty(out))
1154                 set_nonblock(out);
1155         if (!isatty(err))
1156                 set_nonblock(err);
1157
1158         window = CHAN_SES_WINDOW_DEFAULT;
1159         packetmax = CHAN_SES_PACKET_DEFAULT;
1160         if (tty_flag) {
1161                 window >>= 1;
1162                 packetmax >>= 1;
1163         }
1164         c = channel_new(
1165             "session", SSH_CHANNEL_OPENING, in, out, err,
1166             window, packetmax, CHAN_EXTENDED_WRITE,
1167             xstrdup("client-session"), /*nonblock*/0);
1168
1169         debug3("ssh_session2_open: channel_new: %d", c->self);
1170
1171         channel_send_open(c->self);
1172         if (!no_shell_flag)
1173                 channel_register_confirm(c->self, ssh_session2_setup);
1174
1175         return c->self;
1176 }
1177
1178 static int
1179 ssh_session2(void)
1180 {
1181         int id = -1;
1182
1183         /* XXX should be pre-session */
1184         ssh_init_forwarding();
1185
1186         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1187                 id = ssh_session2_open();
1188
1189         /* If requested, let ssh continue in the background. */
1190         if (fork_after_authentication_flag)
1191                 if (daemon(1, 1) < 0)
1192                         fatal("daemon() failed: %.200s", strerror(errno));
1193
1194         return client_loop(tty_flag, tty_flag ?
1195             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1196 }
1197
1198 static void
1199 load_public_identity_files(void)
1200 {
1201         char *filename;
1202         int i = 0;
1203         Key *public;
1204 #ifdef SMARTCARD
1205         Key **keys;
1206
1207         if (options.smartcard_device != NULL &&
1208             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1209             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1210                 int count = 0;
1211                 for (i = 0; keys[i] != NULL; i++) {
1212                         count++;
1213                         memmove(&options.identity_files[1], &options.identity_files[0],
1214                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1215                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1216                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1217                         options.num_identity_files++;
1218                         options.identity_keys[0] = keys[i];
1219                         options.identity_files[0] = xstrdup("smartcard key");;
1220                 }
1221                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1222                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1223                 i = count;
1224                 xfree(keys);
1225         }
1226 #endif /* SMARTCARD */
1227         for (; i < options.num_identity_files; i++) {
1228                 filename = tilde_expand_filename(options.identity_files[i],
1229                     original_real_uid);
1230                 public = key_load_public(filename, NULL);
1231                 debug("identity file %s type %d", filename,
1232                     public ? public->type : -1);
1233                 xfree(options.identity_files[i]);
1234                 options.identity_files[i] = filename;
1235                 options.identity_keys[i] = public;
1236         }
1237 }