ssh.c

   1 /* $OpenBSD: ssh.c,v 1.320 2008/10/08 23:34:03 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * Ssh client program.  This program can be used to log into a remote machine.
   7  * The software supports strong authentication, encryption, and forwarding
   8  * of X11, TCP/IP, and authentication connections.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  17  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  18  *
  19  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  20  * in Canada (German citizen).
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the above copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  *
  31  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  32  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  34  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  35  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  36  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  37  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  38  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  39  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  40  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  41  */
  42
  43 #include "includes.h"
  44
  45 #include <sys/types.h>
  46 #ifdef HAVE_SYS_STAT_H
  47 # include <sys/stat.h>
  48 #endif
  49 #include <sys/resource.h>
  50 #include <sys/ioctl.h>
  51 #include <sys/socket.h>
  52
  53 #include <ctype.h>
  54 #include <errno.h>
  55 #include <fcntl.h>
  56 #include <netdb.h>
  57 #ifdef HAVE_PATHS_H
  58 #include <paths.h>
  59 #endif
  60 #include <pwd.h>
  61 #include <signal.h>
  62 #include <stdarg.h>
  63 #include <stddef.h>
  64 #include <stdio.h>
  65 #include <stdlib.h>
  66 #include <string.h>
  67 #include <unistd.h>
  68
  69 #include <netinet/in.h>
  70 #include <arpa/inet.h>
  71
  72 #include <openssl/evp.h>
  73 #include <openssl/err.h>
  74 #include "openbsd-compat/openssl-compat.h"
  75 #include "openbsd-compat/sys-queue.h"
  76
  77 #include "xmalloc.h"
  78 #include "ssh.h"
  79 #include "ssh1.h"
  80 #include "ssh2.h"
  81 #include "compat.h"
  82 #include "cipher.h"
  83 #include "packet.h"
  84 #include "buffer.h"
  85 #include "channels.h"
  86 #include "key.h"
  87 #include "authfd.h"
  88 #include "authfile.h"
  89 #include "pathnames.h"
  90 #include "dispatch.h"
  91 #include "clientloop.h"
  92 #include "log.h"
  93 #include "readconf.h"
  94 #include "sshconnect.h"
  95 #include "misc.h"
  96 #include "kex.h"
  97 #include "mac.h"
  98 #include "sshpty.h"
  99 #include "match.h"
 100 #include "msg.h"
 101 #include "uidswap.h"
 102 #include "version.h"
 103
 104 #ifdef SMARTCARD
 105 #include "scard.h"
 106 #endif
 107
 108 extern char *__progname;
 109
 110 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 111 int debug_flag = 0;
 112
 113 /* Flag indicating whether a tty should be allocated */
 114 int tty_flag = 0;
 115 int no_tty_flag = 0;
 116 int force_tty_flag = 0;
 117
 118 /* don't exec a shell */
 119 int no_shell_flag = 0;
 120
 121 /*
 122  * Flag indicating that nothing should be read from stdin.  This can be set
 123  * on the command line.
 124  */
 125 int stdin_null_flag = 0;
 126
 127 /*
 128  * Flag indicating that ssh should fork after authentication.  This is useful
 129  * so that the passphrase can be entered manually, and then ssh goes to the
 130  * background.
 131  */
 132 int fork_after_authentication_flag = 0;
 133
 134 /*
 135  * General data structure for command line options and options configurable
 136  * in configuration files.  See readconf.h.
 137  */
 138 Options options;
 139
 140 /* optional user configfile */
 141 char *config = NULL;
 142
 143 /*
 144  * Name of the host we are connecting to.  This is the name given on the
 145  * command line, or the HostName specified for the user-supplied name in a
 146  * configuration file.
 147  */
 148 char *host;
 149
 150 /* socket address the host resolves to */
 151 struct sockaddr_storage hostaddr;
 152
 153 /* Private host keys. */
 154 Sensitive sensitive_data;
 155
 156 /* Original real UID. */
 157 uid_t original_real_uid;
 158 uid_t original_effective_uid;
 159
 160 /* command to be executed */
 161 Buffer command;
 162
 163 /* Should we execute a command or invoke a subsystem? */
 164 int subsystem_flag = 0;
 165
 166 /* # of replies received for global requests */
 167 static int remote_forward_confirms_received = 0;
 168
 169 /* pid of proxycommand child process */
 170 pid_t proxy_command_pid = 0;
 171
 172 /* mux.c */
 173 extern int muxserver_sock;
 174 extern u_int muxclient_command;
 175
 176 /* Prints a help message to the user.  This function never returns. */
 177
 178 static void
 179 usage(void)
 180 {
 181         fprintf(stderr,
 182 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 183 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 184 "           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
 185 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 186 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 187 "           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
 188         );
 189         exit(255);
 190 }
 191
 192 static int ssh_session(void);
 193 static int ssh_session2(void);
 194 static void load_public_identity_files(void);
 195
 196 /* from muxclient.c */
 197 void muxclient(const char *);
 198 void muxserver_listen(void);
 199
 200 /*
 201  * Main program for the ssh client.
 202  */
 203 int
 204 main(int ac, char **av)
 205 {
 206         int i, opt, exit_status, use_syslog;
 207         char *p, *cp, *line, buf[256];
 208         struct stat st;
 209         struct passwd *pw;
 210         int dummy, timeout_ms;
 211         extern int optind, optreset;
 212         extern char *optarg;
 213         struct servent *sp;
 214         Forward fwd;
 215
 216         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 217         sanitise_stdfd();
 218
 219         __progname = ssh_get_progname(av[0]);
 220         init_rng();
 221
 222         /*
 223          * Save the original real uid.  It will be needed later (uid-swapping
 224          * may clobber the real uid).
 225          */
 226         original_real_uid = getuid();
 227         original_effective_uid = geteuid();
 228
 229         /*
 230          * Use uid-swapping to give up root privileges for the duration of
 231          * option processing.  We will re-instantiate the rights when we are
 232          * ready to create the privileged port, and will permanently drop
 233          * them when the port has been created (actually, when the connection
 234          * has been made, as we may need to create the port several times).
 235          */
 236         PRIV_END;
 237
 238 #ifdef HAVE_SETRLIMIT
 239         /* If we are installed setuid root be careful to not drop core. */
 240         if (original_real_uid != original_effective_uid) {
 241                 struct rlimit rlim;
 242                 rlim.rlim_cur = rlim.rlim_max = 0;
 243                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 244                         fatal("setrlimit failed: %.100s", strerror(errno));
 245         }
 246 #endif
 247         /* Get user data. */
 248         pw = getpwuid(original_real_uid);
 249         if (!pw) {
 250                 logit("You don't exist, go away!");
 251                 exit(255);
 252         }
 253         /* Take a copy of the returned structure. */
 254         pw = pwcopy(pw);
 255
 256         /*
 257          * Set our umask to something reasonable, as some files are created
 258          * with the default umask.  This will make them world-readable but
 259          * writable only by the owner, which is ok for all files for which we
 260          * don't set the modes explicitly.
 261          */
 262         umask(022);
 263
 264         /*
 265          * Initialize option structure to indicate that no values have been
 266          * set.
 267          */
 268         initialize_options(&options);
 269
 270         /* Parse command-line arguments. */
 271         host = NULL;
 272         use_syslog = 0;
 273
 274  again:
 275         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 276             "ACD:F:I:KL:MNO:PR:S:TVw:XYy")) != -1) {
 277                 switch (opt) {
 278                 case '1':
 279                         options.protocol = SSH_PROTO_1;
 280                         break;
 281                 case '2':
 282                         options.protocol = SSH_PROTO_2;
 283                         break;
 284                 case '4':
 285                         options.address_family = AF_INET;
 286                         break;
 287                 case '6':
 288                         options.address_family = AF_INET6;
 289                         break;
 290                 case 'n':
 291                         stdin_null_flag = 1;
 292                         break;
 293                 case 'f':
 294                         fork_after_authentication_flag = 1;
 295                         stdin_null_flag = 1;
 296                         break;
 297                 case 'x':
 298                         options.forward_x11 = 0;
 299                         break;
 300                 case 'X':
 301                         options.forward_x11 = 1;
 302                         break;
 303                 case 'y':
 304                         use_syslog = 1;
 305                         break;
 306                 case 'Y':
 307                         options.forward_x11 = 1;
 308                         options.forward_x11_trusted = 1;
 309                         break;
 310                 case 'g':
 311                         options.gateway_ports = 1;
 312                         break;
 313                 case 'O':
 314                         if (strcmp(optarg, "check") == 0)
 315                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 316                         else if (strcmp(optarg, "exit") == 0)
 317                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 318                         else
 319                                 fatal("Invalid multiplex command.");
 320                         break;
 321                 case 'P':       /* deprecated */
 322                         options.use_privileged_port = 0;
 323                         break;
 324                 case 'a':
 325                         options.forward_agent = 0;
 326                         break;
 327                 case 'A':
 328                         options.forward_agent = 1;
 329                         break;
 330                 case 'k':
 331                         options.gss_deleg_creds = 0;
 332                         break;
 333                 case 'K':
 334                         options.gss_authentication = 1;
 335                         options.gss_deleg_creds = 1;
 336                         break;
 337                 case 'i':
 338                         if (stat(optarg, &st) < 0) {
 339                                 fprintf(stderr, "Warning: Identity file %s "
 340                                     "not accessible: %s.\n", optarg,
 341                                     strerror(errno));
 342                                 break;
 343                         }
 344                         if (options.num_identity_files >=
 345                             SSH_MAX_IDENTITY_FILES)
 346                                 fatal("Too many identity files specified "
 347                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 348                         options.identity_files[options.num_identity_files++] =
 349                             xstrdup(optarg);
 350                         break;
 351                 case 'I':
 352 #ifdef SMARTCARD
 353                         options.smartcard_device = xstrdup(optarg);
 354 #else
 355                         fprintf(stderr, "no support for smartcards.\n");
 356 #endif
 357                         break;
 358                 case 't':
 359                         if (tty_flag)
 360                                 force_tty_flag = 1;
 361                         tty_flag = 1;
 362                         break;
 363                 case 'v':
 364                         if (debug_flag == 0) {
 365                                 debug_flag = 1;
 366                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 367                         } else {
 368                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 369                                         options.log_level++;
 370                                 break;
 371                         }
 372                         /* FALLTHROUGH */
 373                 case 'V':
 374                         fprintf(stderr, "%s, %s\n",
 375                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 376                         if (opt == 'V')
 377                                 exit(0);
 378                         break;
 379                 case 'w':
 380                         if (options.tun_open == -1)
 381                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 382                         options.tun_local = a2tun(optarg, &options.tun_remote);
 383                         if (options.tun_local == SSH_TUNID_ERR) {
 384                                 fprintf(stderr,
 385                                     "Bad tun device '%s'\n", optarg);
 386                                 exit(255);
 387                         }
 388                         break;
 389                 case 'q':
 390                         options.log_level = SYSLOG_LEVEL_QUIET;
 391                         break;
 392                 case 'e':
 393                         if (optarg[0] == '^' && optarg[2] == 0 &&
 394                             (u_char) optarg[1] >= 64 &&
 395                             (u_char) optarg[1] < 128)
 396                                 options.escape_char = (u_char) optarg[1] & 31;
 397                         else if (strlen(optarg) == 1)
 398                                 options.escape_char = (u_char) optarg[0];
 399                         else if (strcmp(optarg, "none") == 0)
 400                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 401                         else {
 402                                 fprintf(stderr, "Bad escape character '%s'.\n",
 403                                     optarg);
 404                                 exit(255);
 405                         }
 406                         break;
 407                 case 'c':
 408                         if (ciphers_valid(optarg)) {
 409                                 /* SSH2 only */
 410                                 options.ciphers = xstrdup(optarg);
 411                                 options.cipher = SSH_CIPHER_INVALID;
 412                         } else {
 413                                 /* SSH1 only */
 414                                 options.cipher = cipher_number(optarg);
 415                                 if (options.cipher == -1) {
 416                                         fprintf(stderr,
 417                                             "Unknown cipher type '%s'\n",
 418                                             optarg);
 419                                         exit(255);
 420                                 }
 421                                 if (options.cipher == SSH_CIPHER_3DES)
 422                                         options.ciphers = "3des-cbc";
 423                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 424                                         options.ciphers = "blowfish-cbc";
 425                                 else
 426                                         options.ciphers = (char *)-1;
 427                         }
 428                         break;
 429                 case 'm':
 430                         if (mac_valid(optarg))
 431                                 options.macs = xstrdup(optarg);
 432                         else {
 433                                 fprintf(stderr, "Unknown mac type '%s'\n",
 434                                     optarg);
 435                                 exit(255);
 436                         }
 437                         break;
 438                 case 'M':
 439                         if (options.control_master == SSHCTL_MASTER_YES)
 440                                 options.control_master = SSHCTL_MASTER_ASK;
 441                         else
 442                                 options.control_master = SSHCTL_MASTER_YES;
 443                         break;
 444                 case 'p':
 445                         options.port = a2port(optarg);
 446                         if (options.port == 0) {
 447                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 448                                 exit(255);
 449                         }
 450                         break;
 451                 case 'l':
 452                         options.user = optarg;
 453                         break;
 454
 455                 case 'L':
 456                         if (parse_forward(&fwd, optarg))
 457                                 add_local_forward(&options, &fwd);
 458                         else {
 459                                 fprintf(stderr,
 460                                     "Bad local forwarding specification '%s'\n",
 461                                     optarg);
 462                                 exit(255);
 463                         }
 464                         break;
 465
 466                 case 'R':
 467                         if (parse_forward(&fwd, optarg)) {
 468                                 add_remote_forward(&options, &fwd);
 469                         } else {
 470                                 fprintf(stderr,
 471                                     "Bad remote forwarding specification "
 472                                     "'%s'\n", optarg);
 473                                 exit(255);
 474                         }
 475                         break;
 476
 477                 case 'D':
 478                         cp = p = xstrdup(optarg);
 479                         memset(&fwd, '\0', sizeof(fwd));
 480                         fwd.connect_host = "socks";
 481                         if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
 482                                 fprintf(stderr, "Bad dynamic forwarding "
 483                                     "specification '%.100s'\n", optarg);
 484                                 exit(255);
 485                         }
 486                         if (cp != NULL) {
 487                                 fwd.listen_port = a2port(cp);
 488                                 fwd.listen_host =
 489                                     cleanhostname(fwd.listen_host);
 490                         } else {
 491                                 fwd.listen_port = a2port(fwd.listen_host);
 492                                 fwd.listen_host = NULL;
 493                         }
 494
 495                         if (fwd.listen_port == 0) {
 496                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 497                                     optarg);
 498                                 exit(255);
 499                         }
 500                         add_local_forward(&options, &fwd);
 501                         xfree(p);
 502                         break;
 503
 504                 case 'C':
 505                         options.compression = 1;
 506                         break;
 507                 case 'N':
 508                         no_shell_flag = 1;
 509                         no_tty_flag = 1;
 510                         break;
 511                 case 'T':
 512                         no_tty_flag = 1;
 513                         break;
 514                 case 'o':
 515                         dummy = 1;
 516                         line = xstrdup(optarg);
 517                         if (process_config_line(&options, host ? host : "",
 518                             line, "command-line", 0, &dummy) != 0)
 519                                 exit(255);
 520                         xfree(line);
 521                         break;
 522                 case 's':
 523                         subsystem_flag = 1;
 524                         break;
 525                 case 'S':
 526                         if (options.control_path != NULL)
 527                                 free(options.control_path);
 528                         options.control_path = xstrdup(optarg);
 529                         break;
 530                 case 'b':
 531                         options.bind_address = optarg;
 532                         break;
 533                 case 'F':
 534                         config = optarg;
 535                         break;
 536                 default:
 537                         usage();
 538                 }
 539         }
 540
 541         ac -= optind;
 542         av += optind;
 543
 544         if (ac > 0 && !host && **av != '-') {
 545                 if (strrchr(*av, '@')) {
 546                         p = xstrdup(*av);
 547                         cp = strrchr(p, '@');
 548                         if (cp == NULL || cp == p)
 549                                 usage();
 550                         options.user = p;
 551                         *cp = '\0';
 552                         host = ++cp;
 553                 } else
 554                         host = *av;
 555                 if (ac > 1) {
 556                         optind = optreset = 1;
 557                         goto again;
 558                 }
 559                 ac--, av++;
 560         }
 561
 562         /* Check that we got a host name. */
 563         if (!host)
 564                 usage();
 565
 566         SSLeay_add_all_algorithms();
 567         ERR_load_crypto_strings();
 568
 569         /* Initialize the command to execute on remote host. */
 570         buffer_init(&command);
 571
 572         /*
 573          * Save the command to execute on the remote host in a buffer. There
 574          * is no limit on the length of the command, except by the maximum
 575          * packet size.  Also sets the tty flag if there is no command.
 576          */
 577         if (!ac) {
 578                 /* No command specified - execute shell on a tty. */
 579                 tty_flag = 1;
 580                 if (subsystem_flag) {
 581                         fprintf(stderr,
 582                             "You must specify a subsystem to invoke.\n");
 583                         usage();
 584                 }
 585         } else {
 586                 /* A command has been specified.  Store it into the buffer. */
 587                 for (i = 0; i < ac; i++) {
 588                         if (i)
 589                                 buffer_append(&command, " ", 1);
 590                         buffer_append(&command, av[i], strlen(av[i]));
 591                 }
 592         }
 593
 594         /* Cannot fork to background if no command. */
 595         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 596             !no_shell_flag)
 597                 fatal("Cannot fork into background without a command "
 598                     "to execute.");
 599
 600         /* Allocate a tty by default if no command specified. */
 601         if (buffer_len(&command) == 0)
 602                 tty_flag = 1;
 603
 604         /* Force no tty */
 605         if (no_tty_flag)
 606                 tty_flag = 0;
 607         /* Do not allocate a tty if stdin is not a tty. */
 608         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 609                 if (tty_flag)
 610                         logit("Pseudo-terminal will not be allocated because "
 611                             "stdin is not a terminal.");
 612                 tty_flag = 0;
 613         }
 614
 615         /*
 616          * Initialize "log" output.  Since we are the client all output
 617          * actually goes to stderr.
 618          */
 619         log_init(av[0],
 620             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 621             SYSLOG_FACILITY_USER, !use_syslog);
 622
 623         /*
 624          * Read per-user configuration file.  Ignore the system wide config
 625          * file if the user specifies a config file on the command line.
 626          */
 627         if (config != NULL) {
 628                 if (!read_config_file(config, host, &options, 0))
 629                         fatal("Can't open user config file %.100s: "
 630                             "%.100s", config, strerror(errno));
 631         } else {
 632                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 633                     _PATH_SSH_USER_CONFFILE);
 634                 (void)read_config_file(buf, host, &options, 1);
 635
 636                 /* Read systemwide configuration file after use config. */
 637                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 638                     &options, 0);
 639         }
 640
 641         /* Fill configuration defaults. */
 642         fill_default_options(&options);
 643
 644         channel_set_af(options.address_family);
 645
 646         /* reinit */
 647         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 648
 649         seed_rng();
 650
 651         if (options.user == NULL)
 652                 options.user = xstrdup(pw->pw_name);
 653
 654         /* Get default port if port has not been set. */
 655         if (options.port == 0) {
 656                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 657                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 658         }
 659
 660         if (options.local_command != NULL) {
 661                 char thishost[NI_MAXHOST];
 662
 663                 if (gethostname(thishost, sizeof(thishost)) == -1)
 664                         fatal("gethostname: %s", strerror(errno));
 665                 snprintf(buf, sizeof(buf), "%d", options.port);
 666                 debug3("expanding LocalCommand: %s", options.local_command);
 667                 cp = options.local_command;
 668                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 669                     "h", options.hostname? options.hostname : host,
 670                     "l", thishost, "n", host, "r", options.user, "p", buf,
 671                     "u", pw->pw_name, (char *)NULL);
 672                 debug3("expanded LocalCommand: %s", options.local_command);
 673                 xfree(cp);
 674         }
 675
 676         if (options.hostname != NULL)
 677                 host = options.hostname;
 678
 679         /* force lowercase for hostkey matching */
 680         if (options.host_key_alias != NULL) {
 681                 for (p = options.host_key_alias; *p; p++)
 682                         if (isupper(*p))
 683                                 *p = (char)tolower(*p);
 684         }
 685
 686         if (options.proxy_command != NULL &&
 687             strcmp(options.proxy_command, "none") == 0) {
 688                 xfree(options.proxy_command);
 689                 options.proxy_command = NULL;
 690         }
 691         if (options.control_path != NULL &&
 692             strcmp(options.control_path, "none") == 0) {
 693                 xfree(options.control_path);
 694                 options.control_path = NULL;
 695         }
 696
 697         if (options.control_path != NULL) {
 698                 char thishost[NI_MAXHOST];
 699
 700                 if (gethostname(thishost, sizeof(thishost)) == -1)
 701                         fatal("gethostname: %s", strerror(errno));
 702                 snprintf(buf, sizeof(buf), "%d", options.port);
 703                 cp = tilde_expand_filename(options.control_path,
 704                     original_real_uid);
 705                 xfree(options.control_path);
 706                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 707                     "r", options.user, "l", thishost, (char *)NULL);
 708                 xfree(cp);
 709         }
 710         if (muxclient_command != 0 && options.control_path == NULL)
 711                 fatal("No ControlPath specified for \"-O\" command");
 712         if (options.control_path != NULL)
 713                 muxclient(options.control_path);
 714
 715         timeout_ms = options.connection_timeout * 1000;
 716
 717         /* Open a connection to the remote host. */
 718         if (ssh_connect(host, &hostaddr, options.port,
 719             options.address_family, options.connection_attempts, &timeout_ms,
 720             options.tcp_keep_alive,
 721 #ifdef HAVE_CYGWIN
 722             options.use_privileged_port,
 723 #else
 724             original_effective_uid == 0 && options.use_privileged_port,
 725 #endif
 726             options.proxy_command) != 0)
 727                 exit(255);
 728
 729         if (timeout_ms > 0)
 730                 debug3("timeout: %d ms remain after connect", timeout_ms);
 731
 732         /*
 733          * If we successfully made the connection, load the host private key
 734          * in case we will need it later for combined rsa-rhosts
 735          * authentication. This must be done before releasing extra
 736          * privileges, because the file is only readable by root.
 737          * If we cannot access the private keys, load the public keys
 738          * instead and try to execute the ssh-keysign helper instead.
 739          */
 740         sensitive_data.nkeys = 0;
 741         sensitive_data.keys = NULL;
 742         sensitive_data.external_keysign = 0;
 743         if (options.rhosts_rsa_authentication ||
 744             options.hostbased_authentication) {
 745                 sensitive_data.nkeys = 3;
 746                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 747                     sizeof(Key));
 748
 749                 PRIV_START;
 750                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 751                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 752                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 753                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 754                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 755                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 756                 PRIV_END;
 757
 758                 if (options.hostbased_authentication == 1 &&
 759                     sensitive_data.keys[0] == NULL &&
 760                     sensitive_data.keys[1] == NULL &&
 761                     sensitive_data.keys[2] == NULL) {
 762                         sensitive_data.keys[1] = key_load_public(
 763                             _PATH_HOST_DSA_KEY_FILE, NULL);
 764                         sensitive_data.keys[2] = key_load_public(
 765                             _PATH_HOST_RSA_KEY_FILE, NULL);
 766                         sensitive_data.external_keysign = 1;
 767                 }
 768         }
 769         /*
 770          * Get rid of any extra privileges that we may have.  We will no
 771          * longer need them.  Also, extra privileges could make it very hard
 772          * to read identity files and other non-world-readable files from the
 773          * user's home directory if it happens to be on a NFS volume where
 774          * root is mapped to nobody.
 775          */
 776         if (original_effective_uid == 0) {
 777                 PRIV_START;
 778                 permanently_set_uid(pw);
 779         }
 780
 781         /*
 782          * Now that we are back to our own permissions, create ~/.ssh
 783          * directory if it doesn't already exist.
 784          */
 785         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir,
 786             strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 787         if (stat(buf, &st) < 0)
 788                 if (mkdir(buf, 0700) < 0)
 789                         error("Could not create directory '%.200s'.", buf);
 790
 791         /* load options.identity_files */
 792         load_public_identity_files();
 793
 794         /* Expand ~ in known host file names. */
 795         /* XXX mem-leaks: */
 796         options.system_hostfile =
 797             tilde_expand_filename(options.system_hostfile, original_real_uid);
 798         options.user_hostfile =
 799             tilde_expand_filename(options.user_hostfile, original_real_uid);
 800         options.system_hostfile2 =
 801             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 802         options.user_hostfile2 =
 803             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 804
 805         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 806
 807         /* Log into the remote system.  Never returns if the login fails. */
 808         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 809             pw, timeout_ms);
 810
 811         /* We no longer need the private host keys.  Clear them now. */
 812         if (sensitive_data.nkeys != 0) {
 813                 for (i = 0; i < sensitive_data.nkeys; i++) {
 814                         if (sensitive_data.keys[i] != NULL) {
 815                                 /* Destroys contents safely */
 816                                 debug3("clear hostkey %d", i);
 817                                 key_free(sensitive_data.keys[i]);
 818                                 sensitive_data.keys[i] = NULL;
 819                         }
 820                 }
 821                 xfree(sensitive_data.keys);
 822         }
 823         for (i = 0; i < options.num_identity_files; i++) {
 824                 if (options.identity_files[i]) {
 825                         xfree(options.identity_files[i]);
 826                         options.identity_files[i] = NULL;
 827                 }
 828                 if (options.identity_keys[i]) {
 829                         key_free(options.identity_keys[i]);
 830                         options.identity_keys[i] = NULL;
 831                 }
 832         }
 833
 834         exit_status = compat20 ? ssh_session2() : ssh_session();
 835         packet_close();
 836
 837         if (options.control_path != NULL && muxserver_sock != -1)
 838                 unlink(options.control_path);
 839
 840         /*
 841          * Send SIGHUP to proxy command if used. We don't wait() in
 842          * case it hangs and instead rely on init to reap the child
 843          */
 844         if (proxy_command_pid > 1)
 845                 kill(proxy_command_pid, SIGHUP);
 846
 847         return exit_status;
 848 }
 849
 850 /* Callback for remote forward global requests */
 851 static void
 852 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 853 {
 854         Forward *rfwd = (Forward *)ctxt;
 855
 856         debug("remote forward %s for: listen %d, connect %s:%d",
 857             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
 858             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
 859         if (type == SSH2_MSG_REQUEST_FAILURE) {
 860                 if (options.exit_on_forward_failure)
 861                         fatal("Error: remote port forwarding failed for "
 862                             "listen port %d", rfwd->listen_port);
 863                 else
 864                         logit("Warning: remote port forwarding failed for "
 865                             "listen port %d", rfwd->listen_port);
 866         }
 867         if (++remote_forward_confirms_received == options.num_remote_forwards) {
 868                 debug("All remote forwarding requests processed");
 869                 if (fork_after_authentication_flag) {
 870                         fork_after_authentication_flag = 0;
 871                         if (daemon(1, 1) < 0)
 872                                 fatal("daemon() failed: %.200s",
 873                                     strerror(errno));
 874                 }
 875         }
 876 }
 877
 878 static void
 879 ssh_init_forwarding(void)
 880 {
 881         int success = 0;
 882         int i;
 883
 884         /* Initiate local TCP/IP port forwardings. */
 885         for (i = 0; i < options.num_local_forwards; i++) {
 886                 debug("Local connections to %.200s:%d forwarded to remote "
 887                     "address %.200s:%d",
 888                     (options.local_forwards[i].listen_host == NULL) ?
 889                     (options.gateway_ports ? "*" : "LOCALHOST") :
 890                     options.local_forwards[i].listen_host,
 891                     options.local_forwards[i].listen_port,
 892                     options.local_forwards[i].connect_host,
 893                     options.local_forwards[i].connect_port);
 894                 success += channel_setup_local_fwd_listener(
 895                     options.local_forwards[i].listen_host,
 896                     options.local_forwards[i].listen_port,
 897                     options.local_forwards[i].connect_host,
 898                     options.local_forwards[i].connect_port,
 899                     options.gateway_ports);
 900         }
 901         if (i > 0 && success != i && options.exit_on_forward_failure)
 902                 fatal("Could not request local forwarding.");
 903         if (i > 0 && success == 0)
 904                 error("Could not request local forwarding.");
 905
 906         /* Initiate remote TCP/IP port forwardings. */
 907         for (i = 0; i < options.num_remote_forwards; i++) {
 908                 debug("Remote connections from %.200s:%d forwarded to "
 909                     "local address %.200s:%d",
 910                     (options.remote_forwards[i].listen_host == NULL) ?
 911                     "LOCALHOST" : options.remote_forwards[i].listen_host,
 912                     options.remote_forwards[i].listen_port,
 913                     options.remote_forwards[i].connect_host,
 914                     options.remote_forwards[i].connect_port);
 915                 if (channel_request_remote_forwarding(
 916                     options.remote_forwards[i].listen_host,
 917                     options.remote_forwards[i].listen_port,
 918                     options.remote_forwards[i].connect_host,
 919                     options.remote_forwards[i].connect_port) < 0) {
 920                         if (options.exit_on_forward_failure)
 921                                 fatal("Could not request remote forwarding.");
 922                         else
 923                                 logit("Warning: Could not request remote "
 924                                     "forwarding.");
 925                 }
 926                 client_register_global_confirm(ssh_confirm_remote_forward,
 927                     &options.remote_forwards[i]);
 928         }
 929
 930         /* Initiate tunnel forwarding. */
 931         if (options.tun_open != SSH_TUNMODE_NO) {
 932                 if (client_request_tun_fwd(options.tun_open,
 933                     options.tun_local, options.tun_remote) == -1) {
 934                         if (options.exit_on_forward_failure)
 935                                 fatal("Could not request tunnel forwarding.");
 936                         else
 937                                 error("Could not request tunnel forwarding.");
 938                 }
 939         }
 940 }
 941
 942 static void
 943 check_agent_present(void)
 944 {
 945         if (options.forward_agent) {
 946                 /* Clear agent forwarding if we don't have an agent. */
 947                 if (!ssh_agent_present())
 948                         options.forward_agent = 0;
 949         }
 950 }
 951
 952 static int
 953 ssh_session(void)
 954 {
 955         int type;
 956         int interactive = 0;
 957         int have_tty = 0;
 958         struct winsize ws;
 959         char *cp;
 960         const char *display;
 961
 962         /* Enable compression if requested. */
 963         if (options.compression) {
 964                 debug("Requesting compression at level %d.",
 965                     options.compression_level);
 966
 967                 if (options.compression_level < 1 ||
 968                     options.compression_level > 9)
 969                         fatal("Compression level must be from 1 (fast) to "
 970                             "9 (slow, best).");
 971
 972                 /* Send the request. */
 973                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 974                 packet_put_int(options.compression_level);
 975                 packet_send();
 976                 packet_write_wait();
 977                 type = packet_read();
 978                 if (type == SSH_SMSG_SUCCESS)
 979                         packet_start_compression(options.compression_level);
 980                 else if (type == SSH_SMSG_FAILURE)
 981                         logit("Warning: Remote host refused compression.");
 982                 else
 983                         packet_disconnect("Protocol error waiting for "
 984                             "compression response.");
 985         }
 986         /* Allocate a pseudo tty if appropriate. */
 987         if (tty_flag) {
 988                 debug("Requesting pty.");
 989
 990                 /* Start the packet. */
 991                 packet_start(SSH_CMSG_REQUEST_PTY);
 992
 993                 /* Store TERM in the packet.  There is no limit on the
 994                    length of the string. */
 995                 cp = getenv("TERM");
 996                 if (!cp)
 997                         cp = "";
 998                 packet_put_cstring(cp);
 999
1000                 /* Store window size in the packet. */
1001                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1002                         memset(&ws, 0, sizeof(ws));
1003                 packet_put_int((u_int)ws.ws_row);
1004                 packet_put_int((u_int)ws.ws_col);
1005                 packet_put_int((u_int)ws.ws_xpixel);
1006                 packet_put_int((u_int)ws.ws_ypixel);
1007
1008                 /* Store tty modes in the packet. */
1009                 tty_make_modes(fileno(stdin), NULL);
1010
1011                 /* Send the packet, and wait for it to leave. */
1012                 packet_send();
1013                 packet_write_wait();
1014
1015                 /* Read response from the server. */
1016                 type = packet_read();
1017                 if (type == SSH_SMSG_SUCCESS) {
1018                         interactive = 1;
1019                         have_tty = 1;
1020                 } else if (type == SSH_SMSG_FAILURE)
1021                         logit("Warning: Remote host failed or refused to "
1022                             "allocate a pseudo tty.");
1023                 else
1024                         packet_disconnect("Protocol error waiting for pty "
1025                             "request response.");
1026         }
1027         /* Request X11 forwarding if enabled and DISPLAY is set. */
1028         display = getenv("DISPLAY");
1029         if (options.forward_x11 && display != NULL) {
1030                 char *proto, *data;
1031                 /* Get reasonable local authentication information. */
1032                 client_x11_get_proto(display, options.xauth_location,
1033                     options.forward_x11_trusted, &proto, &data);
1034                 /* Request forwarding with authentication spoofing. */
1035                 debug("Requesting X11 forwarding with authentication "
1036                     "spoofing.");
1037                 x11_request_forwarding_with_spoofing(0, display, proto, data);
1038
1039                 /* Read response from the server. */
1040                 type = packet_read();
1041                 if (type == SSH_SMSG_SUCCESS) {
1042                         interactive = 1;
1043                 } else if (type == SSH_SMSG_FAILURE) {
1044                         logit("Warning: Remote host denied X11 forwarding.");
1045                 } else {
1046                         packet_disconnect("Protocol error waiting for X11 "
1047                             "forwarding");
1048                 }
1049         }
1050         /* Tell the packet module whether this is an interactive session. */
1051         packet_set_interactive(interactive);
1052
1053         /* Request authentication agent forwarding if appropriate. */
1054         check_agent_present();
1055
1056         if (options.forward_agent) {
1057                 debug("Requesting authentication agent forwarding.");
1058                 auth_request_forwarding();
1059
1060                 /* Read response from the server. */
1061                 type = packet_read();
1062                 packet_check_eom();
1063                 if (type != SSH_SMSG_SUCCESS)
1064                         logit("Warning: Remote host denied authentication agent forwarding.");
1065         }
1066
1067         /* Initiate port forwardings. */
1068         ssh_init_forwarding();
1069
1070         /* Execute a local command */
1071         if (options.local_command != NULL &&
1072             options.permit_local_command)
1073                 ssh_local_cmd(options.local_command);
1074
1075         /*
1076          * If requested and we are not interested in replies to remote
1077          * forwarding requests, then let ssh continue in the background.
1078          */
1079         if (fork_after_authentication_flag &&
1080             (!options.exit_on_forward_failure ||
1081             options.num_remote_forwards == 0)) {
1082                 fork_after_authentication_flag = 0;
1083                 if (daemon(1, 1) < 0)
1084                         fatal("daemon() failed: %.200s", strerror(errno));
1085         }
1086
1087         /*
1088          * If a command was specified on the command line, execute the
1089          * command now. Otherwise request the server to start a shell.
1090          */
1091         if (buffer_len(&command) > 0) {
1092                 int len = buffer_len(&command);
1093                 if (len > 900)
1094                         len = 900;
1095                 debug("Sending command: %.*s", len,
1096                     (u_char *)buffer_ptr(&command));
1097                 packet_start(SSH_CMSG_EXEC_CMD);
1098                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1099                 packet_send();
1100                 packet_write_wait();
1101         } else {
1102                 debug("Requesting shell.");
1103                 packet_start(SSH_CMSG_EXEC_SHELL);
1104                 packet_send();
1105                 packet_write_wait();
1106         }
1107
1108         /* Enter the interactive session. */
1109         return client_loop(have_tty, tty_flag ?
1110             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1111 }
1112
1113 /* request pty/x11/agent/tcpfwd/shell for channel */
1114 static void
1115 ssh_session2_setup(int id, void *arg)
1116 {
1117         extern char **environ;
1118         const char *display;
1119         int interactive = tty_flag;
1120
1121         display = getenv("DISPLAY");
1122         if (options.forward_x11 && display != NULL) {
1123                 char *proto, *data;
1124                 /* Get reasonable local authentication information. */
1125                 client_x11_get_proto(display, options.xauth_location,
1126                     options.forward_x11_trusted, &proto, &data);
1127                 /* Request forwarding with authentication spoofing. */
1128                 debug("Requesting X11 forwarding with authentication "
1129                     "spoofing.");
1130                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1131                 interactive = 1;
1132                 /* XXX wait for reply */
1133         }
1134
1135         check_agent_present();
1136         if (options.forward_agent) {
1137                 debug("Requesting authentication agent forwarding.");
1138                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1139                 packet_send();
1140         }
1141
1142         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1143             NULL, fileno(stdin), &command, environ);
1144
1145         packet_set_interactive(interactive);
1146 }
1147
1148 /* open new channel for a session */
1149 static int
1150 ssh_session2_open(void)
1151 {
1152         Channel *c;
1153         int window, packetmax, in, out, err;
1154
1155         if (stdin_null_flag) {
1156                 in = open(_PATH_DEVNULL, O_RDONLY);
1157         } else {
1158                 in = dup(STDIN_FILENO);
1159         }
1160         out = dup(STDOUT_FILENO);
1161         err = dup(STDERR_FILENO);
1162
1163         if (in < 0 || out < 0 || err < 0)
1164                 fatal("dup() in/out/err failed");
1165
1166         /* enable nonblocking unless tty */
1167         if (!isatty(in))
1168                 set_nonblock(in);
1169         if (!isatty(out))
1170                 set_nonblock(out);
1171         if (!isatty(err))
1172                 set_nonblock(err);
1173
1174         window = CHAN_SES_WINDOW_DEFAULT;
1175         packetmax = CHAN_SES_PACKET_DEFAULT;
1176         if (tty_flag) {
1177                 window >>= 1;
1178                 packetmax >>= 1;
1179         }
1180         c = channel_new(
1181             "session", SSH_CHANNEL_OPENING, in, out, err,
1182             window, packetmax, CHAN_EXTENDED_WRITE,
1183             "client-session", /*nonblock*/0);
1184
1185         debug3("ssh_session2_open: channel_new: %d", c->self);
1186
1187         channel_send_open(c->self);
1188         if (!no_shell_flag)
1189                 channel_register_open_confirm(c->self,
1190                     ssh_session2_setup, NULL);
1191
1192         return c->self;
1193 }
1194
1195 static int
1196 ssh_session2(void)
1197 {
1198         int id = -1;
1199
1200         /* XXX should be pre-session */
1201         ssh_init_forwarding();
1202
1203         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1204                 id = ssh_session2_open();
1205
1206         /* If we don't expect to open a new session, then disallow it */
1207         if (options.control_master == SSHCTL_MASTER_NO &&
1208             (datafellows & SSH_NEW_OPENSSH)) {
1209                 debug("Requesting no-more-sessions@openssh.com");
1210                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1211                 packet_put_cstring("no-more-sessions@openssh.com");
1212                 packet_put_char(0);
1213                 packet_send();
1214         }
1215
1216         /* Execute a local command */
1217         if (options.local_command != NULL &&
1218             options.permit_local_command)
1219                 ssh_local_cmd(options.local_command);
1220
1221         /* Start listening for multiplex clients */
1222         muxserver_listen();
1223
1224         /* If requested, let ssh continue in the background. */
1225         if (fork_after_authentication_flag) {
1226                 fork_after_authentication_flag = 0;
1227                 if (daemon(1, 1) < 0)
1228                         fatal("daemon() failed: %.200s", strerror(errno));
1229         }
1230
1231         return client_loop(tty_flag, tty_flag ?
1232             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1233 }
1234
1235 static void
1236 load_public_identity_files(void)
1237 {
1238         char *filename, *cp, thishost[NI_MAXHOST];
1239         char *pwdir = NULL, *pwname = NULL;
1240         int i = 0;
1241         Key *public;
1242         struct passwd *pw;
1243 #ifdef SMARTCARD
1244         Key **keys;
1245
1246         if (options.smartcard_device != NULL &&
1247             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1248             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL) {
1249                 int count = 0;
1250                 for (i = 0; keys[i] != NULL; i++) {
1251                         count++;
1252                         memmove(&options.identity_files[1],
1253                             &options.identity_files[0],
1254                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1255                         memmove(&options.identity_keys[1],
1256                             &options.identity_keys[0],
1257                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1258                         options.num_identity_files++;
1259                         options.identity_keys[0] = keys[i];
1260                         options.identity_files[0] = sc_get_key_label(keys[i]);
1261                 }
1262                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1263                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1264                 i = count;
1265                 xfree(keys);
1266         }
1267 #endif /* SMARTCARD */
1268         if ((pw = getpwuid(original_real_uid)) == NULL)
1269                 fatal("load_public_identity_files: getpwuid failed");
1270         pwname = xstrdup(pw->pw_name);
1271         pwdir = xstrdup(pw->pw_dir);
1272         if (gethostname(thishost, sizeof(thishost)) == -1)
1273                 fatal("load_public_identity_files: gethostname: %s",
1274                     strerror(errno));
1275         for (; i < options.num_identity_files; i++) {
1276                 cp = tilde_expand_filename(options.identity_files[i],
1277                     original_real_uid);
1278                 filename = percent_expand(cp, "d", pwdir,
1279                     "u", pwname, "l", thishost, "h", host,
1280                     "r", options.user, (char *)NULL);
1281                 xfree(cp);
1282                 public = key_load_public(filename, NULL);
1283                 debug("identity file %s type %d", filename,
1284                     public ? public->type : -1);
1285                 xfree(options.identity_files[i]);
1286                 options.identity_files[i] = filename;
1287                 options.identity_keys[i] = public;
1288         }
1289         bzero(pwname, strlen(pwname));
1290         xfree(pwname);
1291         bzero(pwdir, strlen(pwdir));
1292         xfree(pwdir);
1293 }