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 1.196 2003/07/03 08:09:06 djm 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 debug mode is on.  This can be set on the command line. */
  83 int debug_flag = 0;
  84
  85 /* Flag indicating whether a tty should be allocated */
  86 int tty_flag = 0;
  87 int no_tty_flag = 0;
  88 int force_tty_flag = 0;
  89
  90 /* don't exec a shell */
  91 int no_shell_flag = 0;
  92
  93 /*
  94  * Flag indicating that nothing should be read from stdin.  This can be set
  95  * on the command line.
  96  */
  97 int stdin_null_flag = 0;
  98
  99 /*
 100  * Flag indicating that ssh should fork after authentication.  This is useful
 101  * so that the passphrase can be entered manually, and then ssh goes to the
 102  * background.
 103  */
 104 int fork_after_authentication_flag = 0;
 105
 106 /*
 107  * General data structure for command line options and options configurable
 108  * in configuration files.  See readconf.h.
 109  */
 110 Options options;
 111
 112 /* optional user configfile */
 113 char *config = NULL;
 114
 115 /*
 116  * Name of the host we are connecting to.  This is the name given on the
 117  * command line, or the HostName specified for the user-supplied name in a
 118  * configuration file.
 119  */
 120 char *host;
 121
 122 /* socket address the host resolves to */
 123 struct sockaddr_storage hostaddr;
 124
 125 /* Private host keys. */
 126 Sensitive sensitive_data;
 127
 128 /* Original real UID. */
 129 uid_t original_real_uid;
 130 uid_t original_effective_uid;
 131
 132 /* command to be executed */
 133 Buffer command;
 134
 135 /* Should we execute a command or invoke a subsystem? */
 136 int subsystem_flag = 0;
 137
 138 /* # of replies received for global requests */
 139 static int client_global_request_id = 0;
 140
 141 /* pid of proxycommand child process */
 142 pid_t proxy_command_pid = 0;
 143
 144 /* Prints a help message to the user.  This function never returns. */
 145
 146 static void
 147 usage(void)
 148 {
 149         fprintf(stderr, "Usage: %s [options] host [command]\n", __progname);
 150         fprintf(stderr, "Options:\n");
 151         fprintf(stderr, "  -l user     Log in using this user name.\n");
 152         fprintf(stderr, "  -n          Redirect input from " _PATH_DEVNULL ".\n");
 153         fprintf(stderr, "  -F config   Config file (default: ~/%s).\n",
 154              _PATH_SSH_USER_CONFFILE);
 155         fprintf(stderr, "  -A          Enable authentication agent forwarding.\n");
 156         fprintf(stderr, "  -a          Disable authentication agent forwarding (default).\n");
 157 #ifdef AFS
 158         fprintf(stderr, "  -k          Disable Kerberos ticket and AFS token forwarding.\n");
 159 #endif                          /* AFS */
 160         fprintf(stderr, "  -X          Enable X11 connection forwarding.\n");
 161         fprintf(stderr, "  -x          Disable X11 connection forwarding (default).\n");
 162         fprintf(stderr, "  -i file     Identity for public key authentication "
 163             "(default: ~/.ssh/identity)\n");
 164 #ifdef SMARTCARD
 165         fprintf(stderr, "  -I reader   Set smartcard reader.\n");
 166 #endif
 167         fprintf(stderr, "  -t          Tty; allocate a tty even if command is given.\n");
 168         fprintf(stderr, "  -T          Do not allocate a tty.\n");
 169         fprintf(stderr, "  -v          Verbose; display verbose debugging messages.\n");
 170         fprintf(stderr, "              Multiple -v increases verbosity.\n");
 171         fprintf(stderr, "  -V          Display version number only.\n");
 172         fprintf(stderr, "  -q          Quiet; don't display any warning messages.\n");
 173         fprintf(stderr, "  -f          Fork into background after authentication.\n");
 174         fprintf(stderr, "  -e char     Set escape character; ``none'' = disable (default: ~).\n");
 175
 176         fprintf(stderr, "  -c cipher   Select encryption algorithm\n");
 177         fprintf(stderr, "  -m macs     Specify MAC algorithms for protocol version 2.\n");
 178         fprintf(stderr, "  -p port     Connect to this port.  Server must be on the same port.\n");
 179         fprintf(stderr, "  -L listen-port:host:port   Forward local port to remote address\n");
 180         fprintf(stderr, "  -R listen-port:host:port   Forward remote port to local address\n");
 181         fprintf(stderr, "              These cause %s to listen for connections on a port, and\n", __progname);
 182         fprintf(stderr, "              forward them to the other side by connecting to host:port.\n");
 183         fprintf(stderr, "  -D port     Enable dynamic application-level port forwarding.\n");
 184         fprintf(stderr, "  -C          Enable compression.\n");
 185         fprintf(stderr, "  -N          Do not execute a shell or command.\n");
 186         fprintf(stderr, "  -g          Allow remote hosts to connect to forwarded ports.\n");
 187         fprintf(stderr, "  -1          Force protocol version 1.\n");
 188         fprintf(stderr, "  -2          Force protocol version 2.\n");
 189         fprintf(stderr, "  -4          Use IPv4 only.\n");
 190         fprintf(stderr, "  -6          Use IPv6 only.\n");
 191         fprintf(stderr, "  -o 'option' Process the option as if it was read from a configuration file.\n");
 192         fprintf(stderr, "  -s          Invoke command (mandatory) as SSH2 subsystem.\n");
 193         fprintf(stderr, "  -b addr     Local IP address.\n");
 194         exit(1);
 195 }
 196
 197 static int ssh_session(void);
 198 static int ssh_session2(void);
 199 static void load_public_identity_files(void);
 200
 201 /*
 202  * Main program for the ssh client.
 203  */
 204 int
 205 main(int ac, char **av)
 206 {
 207         int i, opt, exit_status;
 208         u_short fwd_port, fwd_host_port;
 209         char sfwd_port[6], sfwd_host_port[6];
 210         char *p, *cp, buf[256];
 211         struct stat st;
 212         struct passwd *pw;
 213         int dummy;
 214         extern int optind, optreset;
 215         extern char *optarg;
 216
 217         __progname = get_progname(av[0]);
 218         init_rng();
 219
 220         /*
 221          * Save the original real uid.  It will be needed later (uid-swapping
 222          * may clobber the real uid).
 223          */
 224         original_real_uid = getuid();
 225         original_effective_uid = geteuid();
 226
 227         /*
 228          * Use uid-swapping to give up root privileges for the duration of
 229          * option processing.  We will re-instantiate the rights when we are
 230          * ready to create the privileged port, and will permanently drop
 231          * them when the port has been created (actually, when the connection
 232          * has been made, as we may need to create the port several times).
 233          */
 234         PRIV_END;
 235
 236 #ifdef HAVE_SETRLIMIT
 237         /* If we are installed setuid root be careful to not drop core. */
 238         if (original_real_uid != original_effective_uid) {
 239                 struct rlimit rlim;
 240                 rlim.rlim_cur = rlim.rlim_max = 0;
 241                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 242                         fatal("setrlimit failed: %.100s", strerror(errno));
 243         }
 244 #endif
 245         /* Get user data. */
 246         pw = getpwuid(original_real_uid);
 247         if (!pw) {
 248                 logit("You don't exist, go away!");
 249                 exit(1);
 250         }
 251         /* Take a copy of the returned structure. */
 252         pw = pwcopy(pw);
 253
 254         /*
 255          * Set our umask to something reasonable, as some files are created
 256          * with the default umask.  This will make them world-readable but
 257          * writable only by the owner, which is ok for all files for which we
 258          * don't set the modes explicitly.
 259          */
 260         umask(022);
 261
 262         /* Initialize option structure to indicate that no values have been set. */
 263         initialize_options(&options);
 264
 265         /* Parse command-line arguments. */
 266         host = NULL;
 267
 268 again:
 269         while ((opt = getopt(ac, av,
 270             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVX")) != -1) {
 271                 switch (opt) {
 272                 case '1':
 273                         options.protocol = SSH_PROTO_1;
 274                         break;
 275                 case '2':
 276                         options.protocol = SSH_PROTO_2;
 277                         break;
 278                 case '4':
 279                         options.address_family = AF_INET;
 280                         break;
 281                 case '6':
 282                         options.address_family = AF_INET6;
 283                         break;
 284                 case 'n':
 285                         stdin_null_flag = 1;
 286                         break;
 287                 case 'f':
 288                         fork_after_authentication_flag = 1;
 289                         stdin_null_flag = 1;
 290                         break;
 291                 case 'x':
 292                         options.forward_x11 = 0;
 293                         break;
 294                 case 'X':
 295                         options.forward_x11 = 1;
 296                         break;
 297                 case 'g':
 298                         options.gateway_ports = 1;
 299                         break;
 300                 case 'P':       /* deprecated */
 301                         options.use_privileged_port = 0;
 302                         break;
 303                 case 'a':
 304                         options.forward_agent = 0;
 305                         break;
 306                 case 'A':
 307                         options.forward_agent = 1;
 308                         break;
 309 #ifdef AFS
 310                 case 'k':
 311                         options.kerberos_tgt_passing = 0;
 312                         options.afs_token_passing = 0;
 313                         break;
 314 #endif
 315                 case 'i':
 316                         if (stat(optarg, &st) < 0) {
 317                                 fprintf(stderr, "Warning: Identity file %s "
 318                                     "does not exist.\n", optarg);
 319                                 break;
 320                         }
 321                         if (options.num_identity_files >=
 322                             SSH_MAX_IDENTITY_FILES)
 323                                 fatal("Too many identity files specified "
 324                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 325                         options.identity_files[options.num_identity_files++] =
 326                             xstrdup(optarg);
 327                         break;
 328                 case 'I':
 329 #ifdef SMARTCARD
 330                         options.smartcard_device = xstrdup(optarg);
 331 #else
 332                         fprintf(stderr, "no support for smartcards.\n");
 333 #endif
 334                         break;
 335                 case 't':
 336                         if (tty_flag)
 337                                 force_tty_flag = 1;
 338                         tty_flag = 1;
 339                         break;
 340                 case 'v':
 341                         if (0 == debug_flag) {
 342                                 debug_flag = 1;
 343                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 344                         } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
 345                                 options.log_level++;
 346                                 break;
 347                         } else
 348                                 fatal("Too high debugging level.");
 349                         /* fallthrough */
 350                 case 'V':
 351                         fprintf(stderr,
 352                             "%s, SSH protocols %d.%d/%d.%d, %s\n",
 353                             SSH_VERSION,
 354                             PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
 355                             PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
 356                             SSLeay_version(SSLEAY_VERSION));
 357                         if (opt == 'V')
 358                                 exit(0);
 359                         break;
 360                 case 'q':
 361                         options.log_level = SYSLOG_LEVEL_QUIET;
 362                         break;
 363                 case 'e':
 364                         if (optarg[0] == '^' && optarg[2] == 0 &&
 365                             (u_char) optarg[1] >= 64 &&
 366                             (u_char) optarg[1] < 128)
 367                                 options.escape_char = (u_char) optarg[1] & 31;
 368                         else if (strlen(optarg) == 1)
 369                                 options.escape_char = (u_char) optarg[0];
 370                         else if (strcmp(optarg, "none") == 0)
 371                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 372                         else {
 373                                 fprintf(stderr, "Bad escape character '%s'.\n",
 374                                     optarg);
 375                                 exit(1);
 376                         }
 377                         break;
 378                 case 'c':
 379                         if (ciphers_valid(optarg)) {
 380                                 /* SSH2 only */
 381                                 options.ciphers = xstrdup(optarg);
 382                                 options.cipher = SSH_CIPHER_ILLEGAL;
 383                         } else {
 384                                 /* SSH1 only */
 385                                 options.cipher = cipher_number(optarg);
 386                                 if (options.cipher == -1) {
 387                                         fprintf(stderr,
 388                                             "Unknown cipher type '%s'\n",
 389                                             optarg);
 390                                         exit(1);
 391                                 }
 392                                 if (options.cipher == SSH_CIPHER_3DES)
 393                                         options.ciphers = "3des-cbc";
 394                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 395                                         options.ciphers = "blowfish-cbc";
 396                                 else
 397                                         options.ciphers = (char *)-1;
 398                         }
 399                         break;
 400                 case 'm':
 401                         if (mac_valid(optarg))
 402                                 options.macs = xstrdup(optarg);
 403                         else {
 404                                 fprintf(stderr, "Unknown mac type '%s'\n",
 405                                     optarg);
 406                                 exit(1);
 407                         }
 408                         break;
 409                 case 'p':
 410                         options.port = a2port(optarg);
 411                         if (options.port == 0) {
 412                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 413                                 exit(1);
 414                         }
 415                         break;
 416                 case 'l':
 417                         options.user = optarg;
 418                         break;
 419
 420                 case 'L':
 421                 case 'R':
 422                         if (sscanf(optarg, "%5[0123456789]:%255[^:]:%5[0123456789]",
 423                             sfwd_port, buf, sfwd_host_port) != 3 &&
 424                             sscanf(optarg, "%5[0123456789]/%255[^/]/%5[0123456789]",
 425                             sfwd_port, buf, sfwd_host_port) != 3) {
 426                                 fprintf(stderr,
 427                                     "Bad forwarding specification '%s'\n",
 428                                     optarg);
 429                                 usage();
 430                                 /* NOTREACHED */
 431                         }
 432                         if ((fwd_port = a2port(sfwd_port)) == 0 ||
 433                             (fwd_host_port = a2port(sfwd_host_port)) == 0) {
 434                                 fprintf(stderr,
 435                                     "Bad forwarding port(s) '%s'\n", optarg);
 436                                 exit(1);
 437                         }
 438                         if (opt == 'L')
 439                                 add_local_forward(&options, fwd_port, buf,
 440                                     fwd_host_port);
 441                         else if (opt == 'R')
 442                                 add_remote_forward(&options, fwd_port, buf,
 443                                     fwd_host_port);
 444                         break;
 445
 446                 case 'D':
 447                         fwd_port = a2port(optarg);
 448                         if (fwd_port == 0) {
 449                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 450                                     optarg);
 451                                 exit(1);
 452                         }
 453                         add_local_forward(&options, fwd_port, "socks4", 0);
 454                         break;
 455
 456                 case 'C':
 457                         options.compression = 1;
 458                         break;
 459                 case 'N':
 460                         no_shell_flag = 1;
 461                         no_tty_flag = 1;
 462                         break;
 463                 case 'T':
 464                         no_tty_flag = 1;
 465                         break;
 466                 case 'o':
 467                         dummy = 1;
 468                         if (process_config_line(&options, host ? host : "",
 469                             optarg, "command-line", 0, &dummy) != 0)
 470                                 exit(1);
 471                         break;
 472                 case 's':
 473                         subsystem_flag = 1;
 474                         break;
 475                 case 'b':
 476                         options.bind_address = optarg;
 477                         break;
 478                 case 'F':
 479                         config = optarg;
 480                         break;
 481                 default:
 482                         usage();
 483                 }
 484         }
 485
 486         ac -= optind;
 487         av += optind;
 488
 489         if (ac > 0 && !host && **av != '-') {
 490                 if (strrchr(*av, '@')) {
 491                         p = xstrdup(*av);
 492                         cp = strrchr(p, '@');
 493                         if (cp == NULL || cp == p)
 494                                 usage();
 495                         options.user = p;
 496                         *cp = '\0';
 497                         host = ++cp;
 498                 } else
 499                         host = *av;
 500                 if (ac > 1) {
 501                         optind = optreset = 1;
 502                         goto again;
 503                 }
 504                 ac--, av++;
 505         }
 506
 507         /* Check that we got a host name. */
 508         if (!host)
 509                 usage();
 510
 511         SSLeay_add_all_algorithms();
 512         ERR_load_crypto_strings();
 513
 514         /* Initialize the command to execute on remote host. */
 515         buffer_init(&command);
 516
 517         /*
 518          * Save the command to execute on the remote host in a buffer. There
 519          * is no limit on the length of the command, except by the maximum
 520          * packet size.  Also sets the tty flag if there is no command.
 521          */
 522         if (!ac) {
 523                 /* No command specified - execute shell on a tty. */
 524                 tty_flag = 1;
 525                 if (subsystem_flag) {
 526                         fprintf(stderr,
 527                             "You must specify a subsystem to invoke.\n");
 528                         usage();
 529                 }
 530         } else {
 531                 /* A command has been specified.  Store it into the buffer. */
 532                 for (i = 0; i < ac; i++) {
 533                         if (i)
 534                                 buffer_append(&command, " ", 1);
 535                         buffer_append(&command, av[i], strlen(av[i]));
 536                 }
 537         }
 538
 539         /* Cannot fork to background if no command. */
 540         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 541                 fatal("Cannot fork into background without a command to execute.");
 542
 543         /* Allocate a tty by default if no command specified. */
 544         if (buffer_len(&command) == 0)
 545                 tty_flag = 1;
 546
 547         /* Force no tty */
 548         if (no_tty_flag)
 549                 tty_flag = 0;
 550         /* Do not allocate a tty if stdin is not a tty. */
 551         if (!isatty(fileno(stdin)) && !force_tty_flag) {
 552                 if (tty_flag)
 553                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 554                 tty_flag = 0;
 555         }
 556
 557         /*
 558          * Initialize "log" output.  Since we are the client all output
 559          * actually goes to stderr.
 560          */
 561         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 562             SYSLOG_FACILITY_USER, 1);
 563
 564         /*
 565          * Read per-user configuration file.  Ignore the system wide config
 566          * file if the user specifies a config file on the command line.
 567          */
 568         if (config != NULL) {
 569                 if (!read_config_file(config, host, &options))
 570                         fatal("Can't open user config file %.100s: "
 571                             "%.100s", config, strerror(errno));
 572         } else  {
 573                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 574                     _PATH_SSH_USER_CONFFILE);
 575                 (void)read_config_file(buf, host, &options);
 576
 577                 /* Read systemwide configuration file after use config. */
 578                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
 579         }
 580
 581         /* Fill configuration defaults. */
 582         fill_default_options(&options);
 583
 584         channel_set_af(options.address_family);
 585
 586         /* reinit */
 587         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 588
 589         seed_rng();
 590
 591         if (options.user == NULL)
 592                 options.user = xstrdup(pw->pw_name);
 593
 594         if (options.hostname != NULL)
 595                 host = options.hostname;
 596
 597         /* force lowercase for hostkey matching */
 598         if (options.host_key_alias != NULL) {
 599                 for (p = options.host_key_alias; *p; p++)
 600                         if (isupper(*p))
 601                                 *p = tolower(*p);
 602         }
 603
 604         if (options.proxy_command != NULL &&
 605             strcmp(options.proxy_command, "none") == 0)
 606                 options.proxy_command = NULL;
 607
 608         /* Disable rhosts authentication if not running as root. */
 609 #ifdef HAVE_CYGWIN
 610         /* Ignore uid if running under Windows */
 611         if (!options.use_privileged_port) {
 612 #else
 613         if (original_effective_uid != 0 || !options.use_privileged_port) {
 614 #endif
 615                 debug("Rhosts Authentication disabled, "
 616                     "originating port will not be trusted.");
 617                 options.rhosts_authentication = 0;
 618         }
 619         /* Open a connection to the remote host. */
 620
 621         if (ssh_connect(host, &hostaddr, options.port,
 622             options.address_family, options.connection_attempts,
 623 #ifdef HAVE_CYGWIN
 624             options.use_privileged_port,
 625 #else
 626             original_effective_uid == 0 && options.use_privileged_port,
 627 #endif
 628             options.proxy_command) != 0)
 629                 exit(1);
 630
 631         /*
 632          * If we successfully made the connection, load the host private key
 633          * in case we will need it later for combined rsa-rhosts
 634          * authentication. This must be done before releasing extra
 635          * privileges, because the file is only readable by root.
 636          * If we cannot access the private keys, load the public keys
 637          * instead and try to execute the ssh-keysign helper instead.
 638          */
 639         sensitive_data.nkeys = 0;
 640         sensitive_data.keys = NULL;
 641         sensitive_data.external_keysign = 0;
 642         if (options.rhosts_rsa_authentication ||
 643             options.hostbased_authentication) {
 644                 sensitive_data.nkeys = 3;
 645                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 646                     sizeof(Key));
 647
 648                 PRIV_START;
 649                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 650                     _PATH_HOST_KEY_FILE, "", NULL);
 651                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 652                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 653                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 654                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 655                 PRIV_END;
 656
 657                 if (options.hostbased_authentication == 1 &&
 658                     sensitive_data.keys[0] == NULL &&
 659                     sensitive_data.keys[1] == NULL &&
 660                     sensitive_data.keys[2] == NULL) {
 661                         sensitive_data.keys[1] = key_load_public(
 662                             _PATH_HOST_DSA_KEY_FILE, NULL);
 663                         sensitive_data.keys[2] = key_load_public(
 664                             _PATH_HOST_RSA_KEY_FILE, NULL);
 665                         sensitive_data.external_keysign = 1;
 666                 }
 667         }
 668         /*
 669          * Get rid of any extra privileges that we may have.  We will no
 670          * longer need them.  Also, extra privileges could make it very hard
 671          * to read identity files and other non-world-readable files from the
 672          * user's home directory if it happens to be on a NFS volume where
 673          * root is mapped to nobody.
 674          */
 675         seteuid(original_real_uid);
 676         setuid(original_real_uid);
 677
 678         /*
 679          * Now that we are back to our own permissions, create ~/.ssh
 680          * directory if it doesn\'t already exist.
 681          */
 682         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 683         if (stat(buf, &st) < 0)
 684                 if (mkdir(buf, 0700) < 0)
 685                         error("Could not create directory '%.200s'.", buf);
 686
 687         /* load options.identity_files */
 688         load_public_identity_files();
 689
 690         /* Expand ~ in known host file names. */
 691         /* XXX mem-leaks: */
 692         options.system_hostfile =
 693             tilde_expand_filename(options.system_hostfile, original_real_uid);
 694         options.user_hostfile =
 695             tilde_expand_filename(options.user_hostfile, original_real_uid);
 696         options.system_hostfile2 =
 697             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 698         options.user_hostfile2 =
 699             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 700
 701         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 702
 703         /* Log into the remote system.  This never returns if the login fails. */
 704         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 705
 706         /* We no longer need the private host keys.  Clear them now. */
 707         if (sensitive_data.nkeys != 0) {
 708                 for (i = 0; i < sensitive_data.nkeys; i++) {
 709                         if (sensitive_data.keys[i] != NULL) {
 710                                 /* Destroys contents safely */
 711                                 debug3("clear hostkey %d", i);
 712                                 key_free(sensitive_data.keys[i]);
 713                                 sensitive_data.keys[i] = NULL;
 714                         }
 715                 }
 716                 xfree(sensitive_data.keys);
 717         }
 718         for (i = 0; i < options.num_identity_files; i++) {
 719                 if (options.identity_files[i]) {
 720                         xfree(options.identity_files[i]);
 721                         options.identity_files[i] = NULL;
 722                 }
 723                 if (options.identity_keys[i]) {
 724                         key_free(options.identity_keys[i]);
 725                         options.identity_keys[i] = NULL;
 726                 }
 727         }
 728
 729         exit_status = compat20 ? ssh_session2() : ssh_session();
 730         packet_close();
 731
 732         /*
 733          * Send SIGHUP to proxy command if used. We don't wait() in
 734          * case it hangs and instead rely on init to reap the child
 735          */
 736         if (proxy_command_pid > 1)
 737                 kill(proxy_command_pid, SIGHUP);
 738
 739         return exit_status;
 740 }
 741
 742 static void
 743 x11_get_proto(char **_proto, char **_data)
 744 {
 745         char line[512];
 746         static char proto[512], data[512];
 747         FILE *f;
 748         int got_data = 0, i;
 749         char *display;
 750         struct stat st;
 751
 752         *_proto = proto;
 753         *_data = data;
 754         proto[0] = data[0] = '\0';
 755         if (!options.xauth_location ||
 756             (stat(options.xauth_location, &st) == -1)) {
 757                 debug("No xauth program.");
 758         } else {
 759                 if ((display = getenv("DISPLAY")) == NULL) {
 760                         debug("x11_get_proto: DISPLAY not set");
 761                         return;
 762                 }
 763                 /* Try to get Xauthority information for the display. */
 764                 if (strncmp(display, "localhost:", 10) == 0)
 765                         /*
 766                          * Handle FamilyLocal case where $DISPLAY does
 767                          * not match an authorization entry.  For this we
 768                          * just try "xauth list unix:displaynum.screennum".
 769                          * XXX: "localhost" match to determine FamilyLocal
 770                          *      is not perfect.
 771                          */
 772                         snprintf(line, sizeof line, "%s list unix:%s 2>"
 773                             _PATH_DEVNULL, options.xauth_location, display+10);
 774                 else
 775                         snprintf(line, sizeof line, "%s list %.200s 2>"
 776                             _PATH_DEVNULL, options.xauth_location, display);
 777                 debug2("x11_get_proto: %s", line);
 778                 f = popen(line, "r");
 779                 if (f && fgets(line, sizeof(line), f) &&
 780                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 781                         got_data = 1;
 782                 if (f)
 783                         pclose(f);
 784         }
 785         /*
 786          * If we didn't get authentication data, just make up some
 787          * data.  The forwarding code will check the validity of the
 788          * response anyway, and substitute this data.  The X11
 789          * server, however, will ignore this fake data and use
 790          * whatever authentication mechanisms it was using otherwise
 791          * for the local connection.
 792          */
 793         if (!got_data) {
 794                 u_int32_t rand = 0;
 795
 796                 logit("Warning: No xauth data; using fake authentication data for X11 forwarding.");
 797                 strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
 798                 for (i = 0; i < 16; i++) {
 799                         if (i % 4 == 0)
 800                                 rand = arc4random();
 801                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
 802                         rand >>= 8;
 803                 }
 804         }
 805 }
 806
 807 static void
 808 ssh_init_forwarding(void)
 809 {
 810         int success = 0;
 811         int i;
 812
 813         /* Initiate local TCP/IP port forwardings. */
 814         for (i = 0; i < options.num_local_forwards; i++) {
 815                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
 816                     options.local_forwards[i].port,
 817                     options.local_forwards[i].host,
 818                     options.local_forwards[i].host_port);
 819                 success += channel_setup_local_fwd_listener(
 820                     options.local_forwards[i].port,
 821                     options.local_forwards[i].host,
 822                     options.local_forwards[i].host_port,
 823                     options.gateway_ports);
 824         }
 825         if (i > 0 && success == 0)
 826                 error("Could not request local forwarding.");
 827
 828         /* Initiate remote TCP/IP port forwardings. */
 829         for (i = 0; i < options.num_remote_forwards; i++) {
 830                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
 831                     options.remote_forwards[i].port,
 832                     options.remote_forwards[i].host,
 833                     options.remote_forwards[i].host_port);
 834                 channel_request_remote_forwarding(
 835                     options.remote_forwards[i].port,
 836                     options.remote_forwards[i].host,
 837                     options.remote_forwards[i].host_port);
 838         }
 839 }
 840
 841 static void
 842 check_agent_present(void)
 843 {
 844         if (options.forward_agent) {
 845                 /* Clear agent forwarding if we don\'t have an agent. */
 846                 if (!ssh_agent_present())
 847                         options.forward_agent = 0;
 848         }
 849 }
 850
 851 static int
 852 ssh_session(void)
 853 {
 854         int type;
 855         int interactive = 0;
 856         int have_tty = 0;
 857         struct winsize ws;
 858         char *cp;
 859
 860         /* Enable compression if requested. */
 861         if (options.compression) {
 862                 debug("Requesting compression at level %d.", options.compression_level);
 863
 864                 if (options.compression_level < 1 || options.compression_level > 9)
 865                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 866
 867                 /* Send the request. */
 868                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 869                 packet_put_int(options.compression_level);
 870                 packet_send();
 871                 packet_write_wait();
 872                 type = packet_read();
 873                 if (type == SSH_SMSG_SUCCESS)
 874                         packet_start_compression(options.compression_level);
 875                 else if (type == SSH_SMSG_FAILURE)
 876                         logit("Warning: Remote host refused compression.");
 877                 else
 878                         packet_disconnect("Protocol error waiting for compression response.");
 879         }
 880         /* Allocate a pseudo tty if appropriate. */
 881         if (tty_flag) {
 882                 debug("Requesting pty.");
 883
 884                 /* Start the packet. */
 885                 packet_start(SSH_CMSG_REQUEST_PTY);
 886
 887                 /* Store TERM in the packet.  There is no limit on the
 888                    length of the string. */
 889                 cp = getenv("TERM");
 890                 if (!cp)
 891                         cp = "";
 892                 packet_put_cstring(cp);
 893
 894                 /* Store window size in the packet. */
 895                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 896                         memset(&ws, 0, sizeof(ws));
 897                 packet_put_int(ws.ws_row);
 898                 packet_put_int(ws.ws_col);
 899                 packet_put_int(ws.ws_xpixel);
 900                 packet_put_int(ws.ws_ypixel);
 901
 902                 /* Store tty modes in the packet. */
 903                 tty_make_modes(fileno(stdin), NULL);
 904
 905                 /* Send the packet, and wait for it to leave. */
 906                 packet_send();
 907                 packet_write_wait();
 908
 909                 /* Read response from the server. */
 910                 type = packet_read();
 911                 if (type == SSH_SMSG_SUCCESS) {
 912                         interactive = 1;
 913                         have_tty = 1;
 914                 } else if (type == SSH_SMSG_FAILURE)
 915                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 916                 else
 917                         packet_disconnect("Protocol error waiting for pty request response.");
 918         }
 919         /* Request X11 forwarding if enabled and DISPLAY is set. */
 920         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 921                 char *proto, *data;
 922                 /* Get reasonable local authentication information. */
 923                 x11_get_proto(&proto, &data);
 924                 /* Request forwarding with authentication spoofing. */
 925                 debug("Requesting X11 forwarding with authentication spoofing.");
 926                 x11_request_forwarding_with_spoofing(0, proto, data);
 927
 928                 /* Read response from the server. */
 929                 type = packet_read();
 930                 if (type == SSH_SMSG_SUCCESS) {
 931                         interactive = 1;
 932                 } else if (type == SSH_SMSG_FAILURE) {
 933                         logit("Warning: Remote host denied X11 forwarding.");
 934                 } else {
 935                         packet_disconnect("Protocol error waiting for X11 forwarding");
 936                 }
 937         }
 938         /* Tell the packet module whether this is an interactive session. */
 939         packet_set_interactive(interactive);
 940
 941         /* Request authentication agent forwarding if appropriate. */
 942         check_agent_present();
 943
 944         if (options.forward_agent) {
 945                 debug("Requesting authentication agent forwarding.");
 946                 auth_request_forwarding();
 947
 948                 /* Read response from the server. */
 949                 type = packet_read();
 950                 packet_check_eom();
 951                 if (type != SSH_SMSG_SUCCESS)
 952                         logit("Warning: Remote host denied authentication agent forwarding.");
 953         }
 954
 955         /* Initiate port forwardings. */
 956         ssh_init_forwarding();
 957
 958         /* If requested, let ssh continue in the background. */
 959         if (fork_after_authentication_flag)
 960                 if (daemon(1, 1) < 0)
 961                         fatal("daemon() failed: %.200s", strerror(errno));
 962
 963         /*
 964          * If a command was specified on the command line, execute the
 965          * command now. Otherwise request the server to start a shell.
 966          */
 967         if (buffer_len(&command) > 0) {
 968                 int len = buffer_len(&command);
 969                 if (len > 900)
 970                         len = 900;
 971                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 972                 packet_start(SSH_CMSG_EXEC_CMD);
 973                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 974                 packet_send();
 975                 packet_write_wait();
 976         } else {
 977                 debug("Requesting shell.");
 978                 packet_start(SSH_CMSG_EXEC_SHELL);
 979                 packet_send();
 980                 packet_write_wait();
 981         }
 982
 983         /* Enter the interactive session. */
 984         return client_loop(have_tty, tty_flag ?
 985             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
 986 }
 987
 988 static void
 989 client_subsystem_reply(int type, u_int32_t seq, void *ctxt)
 990 {
 991         int id, len;
 992
 993         id = packet_get_int();
 994         len = buffer_len(&command);
 995         if (len > 900)
 996                 len = 900;
 997         packet_check_eom();
 998         if (type == SSH2_MSG_CHANNEL_FAILURE)
 999                 fatal("Request for subsystem '%.*s' failed on channel %d",
1000                     len, (u_char *)buffer_ptr(&command), id);
1001 }
1002
1003 void
1004 client_global_request_reply(int type, u_int32_t seq, void *ctxt)
1005 {
1006         int i;
1007
1008         i = client_global_request_id++;
1009         if (i >= options.num_remote_forwards) {
1010                 debug("client_global_request_reply: too many replies %d > %d",
1011                     i, options.num_remote_forwards);
1012                 return;
1013         }
1014         debug("remote forward %s for: listen %d, connect %s:%d",
1015             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1016             options.remote_forwards[i].port,
1017             options.remote_forwards[i].host,
1018             options.remote_forwards[i].host_port);
1019         if (type == SSH2_MSG_REQUEST_FAILURE)
1020                 logit("Warning: remote port forwarding failed for listen port %d",
1021                     options.remote_forwards[i].port);
1022 }
1023
1024 /* request pty/x11/agent/tcpfwd/shell for channel */
1025 static void
1026 ssh_session2_setup(int id, void *arg)
1027 {
1028         int len;
1029         int interactive = 0;
1030         struct termios tio;
1031
1032         debug2("ssh_session2_setup: id %d", id);
1033
1034         if (tty_flag) {
1035                 struct winsize ws;
1036                 char *cp;
1037                 cp = getenv("TERM");
1038                 if (!cp)
1039                         cp = "";
1040                 /* Store window size in the packet. */
1041                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1042                         memset(&ws, 0, sizeof(ws));
1043
1044                 channel_request_start(id, "pty-req", 0);
1045                 packet_put_cstring(cp);
1046                 packet_put_int(ws.ws_col);
1047                 packet_put_int(ws.ws_row);
1048                 packet_put_int(ws.ws_xpixel);
1049                 packet_put_int(ws.ws_ypixel);
1050                 tio = get_saved_tio();
1051                 tty_make_modes(/*ignored*/ 0, &tio);
1052                 packet_send();
1053                 interactive = 1;
1054                 /* XXX wait for reply */
1055         }
1056         if (options.forward_x11 &&
1057             getenv("DISPLAY") != NULL) {
1058                 char *proto, *data;
1059                 /* Get reasonable local authentication information. */
1060                 x11_get_proto(&proto, &data);
1061                 /* Request forwarding with authentication spoofing. */
1062                 debug("Requesting X11 forwarding with authentication spoofing.");
1063                 x11_request_forwarding_with_spoofing(id, proto, data);
1064                 interactive = 1;
1065                 /* XXX wait for reply */
1066         }
1067
1068         check_agent_present();
1069         if (options.forward_agent) {
1070                 debug("Requesting authentication agent forwarding.");
1071                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1072                 packet_send();
1073         }
1074
1075         len = buffer_len(&command);
1076         if (len > 0) {
1077                 if (len > 900)
1078                         len = 900;
1079                 if (subsystem_flag) {
1080                         debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command));
1081                         channel_request_start(id, "subsystem", /*want reply*/ 1);
1082                         /* register callback for reply */
1083                         /* XXX we assume that client_loop has already been called */
1084                         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
1085                         dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1086                 } else {
1087                         debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1088                         channel_request_start(id, "exec", 0);
1089                 }
1090                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1091                 packet_send();
1092         } else {
1093                 channel_request_start(id, "shell", 0);
1094                 packet_send();
1095         }
1096
1097         packet_set_interactive(interactive);
1098 }
1099
1100 /* open new channel for a session */
1101 static int
1102 ssh_session2_open(void)
1103 {
1104         Channel *c;
1105         int window, packetmax, in, out, err;
1106
1107         if (stdin_null_flag) {
1108                 in = open(_PATH_DEVNULL, O_RDONLY);
1109         } else {
1110                 in = dup(STDIN_FILENO);
1111         }
1112         out = dup(STDOUT_FILENO);
1113         err = dup(STDERR_FILENO);
1114
1115         if (in < 0 || out < 0 || err < 0)
1116                 fatal("dup() in/out/err failed");
1117
1118         /* enable nonblocking unless tty */
1119         if (!isatty(in))
1120                 set_nonblock(in);
1121         if (!isatty(out))
1122                 set_nonblock(out);
1123         if (!isatty(err))
1124                 set_nonblock(err);
1125
1126         window = CHAN_SES_WINDOW_DEFAULT;
1127         packetmax = CHAN_SES_PACKET_DEFAULT;
1128         if (tty_flag) {
1129                 window >>= 1;
1130                 packetmax >>= 1;
1131         }
1132         c = channel_new(
1133             "session", SSH_CHANNEL_OPENING, in, out, err,
1134             window, packetmax, CHAN_EXTENDED_WRITE,
1135             "client-session", /*nonblock*/0);
1136
1137         debug3("ssh_session2_open: channel_new: %d", c->self);
1138
1139         channel_send_open(c->self);
1140         if (!no_shell_flag)
1141                 channel_register_confirm(c->self, ssh_session2_setup);
1142
1143         return c->self;
1144 }
1145
1146 static int
1147 ssh_session2(void)
1148 {
1149         int id = -1;
1150
1151         /* XXX should be pre-session */
1152         ssh_init_forwarding();
1153
1154         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1155                 id = ssh_session2_open();
1156
1157         /* If requested, let ssh continue in the background. */
1158         if (fork_after_authentication_flag)
1159                 if (daemon(1, 1) < 0)
1160                         fatal("daemon() failed: %.200s", strerror(errno));
1161
1162         return client_loop(tty_flag, tty_flag ?
1163             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1164 }
1165
1166 static void
1167 load_public_identity_files(void)
1168 {
1169         char *filename;
1170         int i = 0;
1171         Key *public;
1172 #ifdef SMARTCARD
1173         Key **keys;
1174
1175         if (options.smartcard_device != NULL &&
1176             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1177             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1178                 int count = 0;
1179                 for (i = 0; keys[i] != NULL; i++) {
1180                         count++;
1181                         memmove(&options.identity_files[1], &options.identity_files[0],
1182                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1183                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1184                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1185                         options.num_identity_files++;
1186                         options.identity_keys[0] = keys[i];
1187                         options.identity_files[0] = sc_get_key_label(keys[i]);
1188                 }
1189                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1190                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1191                 i = count;
1192                 xfree(keys);
1193         }
1194 #endif /* SMARTCARD */
1195         for (; i < options.num_identity_files; i++) {
1196                 filename = tilde_expand_filename(options.identity_files[i],
1197                     original_real_uid);
1198                 public = key_load_public(filename, NULL);
1199                 debug("identity file %s type %d", filename,
1200                     public ? public->type : -1);
1201                 xfree(options.identity_files[i]);
1202                 options.identity_files[i] = filename;
1203                 options.identity_keys[i] = public;
1204         }
1205 }