crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.356 2011/01/06 22:23:53 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/param.h>
  52 #include <sys/socket.h>
  53 #include <sys/wait.h>
  54
  55 #include <ctype.h>
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #include <netdb.h>
  59 #ifdef HAVE_PATHS_H
  60 #include <paths.h>
  61 #endif
  62 #include <pwd.h>
  63 #include <signal.h>
  64 #include <stdarg.h>
  65 #include <stddef.h>
  66 #include <stdio.h>
  67 #include <stdlib.h>
  68 #include <string.h>
  69 #include <unistd.h>
  70
  71 #include <netinet/in.h>
  72 #include <arpa/inet.h>
  73
  74 #include <openssl/evp.h>
  75 #include <openssl/err.h>
  76 #include "openbsd-compat/openssl-compat.h"
  77 #include "openbsd-compat/sys-queue.h"
  78
  79 #include "xmalloc.h"
  80 #include "ssh.h"
  81 #include "ssh1.h"
  82 #include "ssh2.h"
  83 #include "canohost.h"
  84 #include "compat.h"
  85 #include "cipher.h"
  86 #include "packet.h"
  87 #include "buffer.h"
  88 #include "channels.h"
  89 #include "key.h"
  90 #include "authfd.h"
  91 #include "authfile.h"
  92 #include "pathnames.h"
  93 #include "dispatch.h"
  94 #include "clientloop.h"
  95 #include "log.h"
  96 #include "readconf.h"
  97 #include "sshconnect.h"
  98 #include "misc.h"
  99 #include "kex.h"
 100 #include "mac.h"
 101 #include "sshpty.h"
 102 #include "match.h"
 103 #include "msg.h"
 104 #include "uidswap.h"
 105 #include "roaming.h"
 106 #include "version.h"
 107
 108 #ifdef ENABLE_PKCS11
 109 #include "ssh-pkcs11.h"
 110 #endif
 111
 112 extern char *__progname;
 113
 114 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 115 int debug_flag = 0;
 116
 117 /* Flag indicating whether a tty should be allocated */
 118 int tty_flag = 0;
 119 int no_tty_flag = 0;
 120 int force_tty_flag = 0;
 121
 122 /* don't exec a shell */
 123 int no_shell_flag = 0;
 124
 125 /*
 126  * Flag indicating that nothing should be read from stdin.  This can be set
 127  * on the command line.
 128  */
 129 int stdin_null_flag = 0;
 130
 131 /*
 132  * Flag indicating that the current process should be backgrounded and
 133  * a new slave launched in the foreground for ControlPersist.
 134  */
 135 int need_controlpersist_detach = 0;
 136
 137 /* Copies of flags for ControlPersist foreground slave */
 138 int ostdin_null_flag, ono_shell_flag, ono_tty_flag, otty_flag;
 139
 140 /*
 141  * Flag indicating that ssh should fork after authentication.  This is useful
 142  * so that the passphrase can be entered manually, and then ssh goes to the
 143  * background.
 144  */
 145 int fork_after_authentication_flag = 0;
 146
 147 /* forward stdio to remote host and port */
 148 char *stdio_forward_host = NULL;
 149 int stdio_forward_port = 0;
 150
 151 /*
 152  * General data structure for command line options and options configurable
 153  * in configuration files.  See readconf.h.
 154  */
 155 Options options;
 156
 157 /* optional user configfile */
 158 char *config = NULL;
 159
 160 /*
 161  * Name of the host we are connecting to.  This is the name given on the
 162  * command line, or the HostName specified for the user-supplied name in a
 163  * configuration file.
 164  */
 165 char *host;
 166
 167 /* socket address the host resolves to */
 168 struct sockaddr_storage hostaddr;
 169
 170 /* Private host keys. */
 171 Sensitive sensitive_data;
 172
 173 /* Original real UID. */
 174 uid_t original_real_uid;
 175 uid_t original_effective_uid;
 176
 177 /* command to be executed */
 178 Buffer command;
 179
 180 /* Should we execute a command or invoke a subsystem? */
 181 int subsystem_flag = 0;
 182
 183 /* # of replies received for global requests */
 184 static int remote_forward_confirms_received = 0;
 185
 186 /* mux.c */
 187 extern int muxserver_sock;
 188 extern u_int muxclient_command;
 189
 190 /* Prints a help message to the user.  This function never returns. */
 191
 192 static void
 193 usage(void)
 194 {
 195         fprintf(stderr,
 196 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
 197 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 198 "           [-I pkcs11] [-i identity_file]\n"
 199 "           [-L [bind_address:]port:host:hostport]\n"
 200 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 201 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 202 "           [-W host:port] [-w local_tun[:remote_tun]]\n"
 203 "           [user@]hostname [command]\n"
 204         );
 205         exit(255);
 206 }
 207
 208 static int ssh_session(void);
 209 static int ssh_session2(void);
 210 static void load_public_identity_files(void);
 211 static void main_sigchld_handler(int);
 212
 213 /* from muxclient.c */
 214 void muxclient(const char *);
 215 void muxserver_listen(void);
 216
 217 /*
 218  * Main program for the ssh client.
 219  */
 220 int
 221 main(int ac, char **av)
 222 {
 223         int i, r, opt, exit_status, use_syslog;
 224         char *p, *cp, *line, *argv0, buf[MAXPATHLEN], *host_arg;
 225         struct stat st;
 226         struct passwd *pw;
 227         int dummy, timeout_ms;
 228         extern int optind, optreset;
 229         extern char *optarg;
 230         struct servent *sp;
 231         Forward fwd;
 232
 233         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 234         sanitise_stdfd();
 235
 236         __progname = ssh_get_progname(av[0]);
 237         init_rng();
 238
 239         /*
 240          * Discard other fds that are hanging around. These can cause problem
 241          * with backgrounded ssh processes started by ControlPersist.
 242          */
 243         closefrom(STDERR_FILENO + 1);
 244
 245         /*
 246          * Save the original real uid.  It will be needed later (uid-swapping
 247          * may clobber the real uid).
 248          */
 249         original_real_uid = getuid();
 250         original_effective_uid = geteuid();
 251
 252         /*
 253          * Use uid-swapping to give up root privileges for the duration of
 254          * option processing.  We will re-instantiate the rights when we are
 255          * ready to create the privileged port, and will permanently drop
 256          * them when the port has been created (actually, when the connection
 257          * has been made, as we may need to create the port several times).
 258          */
 259         PRIV_END;
 260
 261 #ifdef HAVE_SETRLIMIT
 262         /* If we are installed setuid root be careful to not drop core. */
 263         if (original_real_uid != original_effective_uid) {
 264                 struct rlimit rlim;
 265                 rlim.rlim_cur = rlim.rlim_max = 0;
 266                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 267                         fatal("setrlimit failed: %.100s", strerror(errno));
 268         }
 269 #endif
 270         /* Get user data. */
 271         pw = getpwuid(original_real_uid);
 272         if (!pw) {
 273                 logit("You don't exist, go away!");
 274                 exit(255);
 275         }
 276         /* Take a copy of the returned structure. */
 277         pw = pwcopy(pw);
 278
 279         /*
 280          * Set our umask to something reasonable, as some files are created
 281          * with the default umask.  This will make them world-readable but
 282          * writable only by the owner, which is ok for all files for which we
 283          * don't set the modes explicitly.
 284          */
 285         umask(022);
 286
 287         /*
 288          * Initialize option structure to indicate that no values have been
 289          * set.
 290          */
 291         initialize_options(&options);
 292
 293         /* Parse command-line arguments. */
 294         host = NULL;
 295         use_syslog = 0;
 296         argv0 = av[0];
 297
 298  again:
 299         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 300             "ACD:F:I:KL:MNO:PR:S:TVw:W:XYy")) != -1) {
 301                 switch (opt) {
 302                 case '1':
 303                         options.protocol = SSH_PROTO_1;
 304                         break;
 305                 case '2':
 306                         options.protocol = SSH_PROTO_2;
 307                         break;
 308                 case '4':
 309                         options.address_family = AF_INET;
 310                         break;
 311                 case '6':
 312                         options.address_family = AF_INET6;
 313                         break;
 314                 case 'n':
 315                         stdin_null_flag = 1;
 316                         break;
 317                 case 'f':
 318                         fork_after_authentication_flag = 1;
 319                         stdin_null_flag = 1;
 320                         break;
 321                 case 'x':
 322                         options.forward_x11 = 0;
 323                         break;
 324                 case 'X':
 325                         options.forward_x11 = 1;
 326                         break;
 327                 case 'y':
 328                         use_syslog = 1;
 329                         break;
 330                 case 'Y':
 331                         options.forward_x11 = 1;
 332                         options.forward_x11_trusted = 1;
 333                         break;
 334                 case 'g':
 335                         options.gateway_ports = 1;
 336                         break;
 337                 case 'O':
 338                         if (stdio_forward_host != NULL)
 339                                 fatal("Cannot specify multiplexing "
 340                                     "command with -W");
 341                         else if (muxclient_command != 0)
 342                                 fatal("Multiplexing command already specified");
 343                         if (strcmp(optarg, "check") == 0)
 344                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 345                         else if (strcmp(optarg, "forward") == 0)
 346                                 muxclient_command = SSHMUX_COMMAND_FORWARD;
 347                         else if (strcmp(optarg, "exit") == 0)
 348                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 349                         else
 350                                 fatal("Invalid multiplex command.");
 351                         break;
 352                 case 'P':       /* deprecated */
 353                         options.use_privileged_port = 0;
 354                         break;
 355                 case 'a':
 356                         options.forward_agent = 0;
 357                         break;
 358                 case 'A':
 359                         options.forward_agent = 1;
 360                         break;
 361                 case 'k':
 362                         options.gss_deleg_creds = 0;
 363                         break;
 364                 case 'K':
 365                         options.gss_authentication = 1;
 366                         options.gss_deleg_creds = 1;
 367                         break;
 368                 case 'i':
 369                         if (stat(optarg, &st) < 0) {
 370                                 fprintf(stderr, "Warning: Identity file %s "
 371                                     "not accessible: %s.\n", optarg,
 372                                     strerror(errno));
 373                                 break;
 374                         }
 375                         if (options.num_identity_files >=
 376                             SSH_MAX_IDENTITY_FILES)
 377                                 fatal("Too many identity files specified "
 378                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 379                         options.identity_files[options.num_identity_files++] =
 380                             xstrdup(optarg);
 381                         break;
 382                 case 'I':
 383 #ifdef ENABLE_PKCS11
 384                         options.pkcs11_provider = xstrdup(optarg);
 385 #else
 386                         fprintf(stderr, "no support for PKCS#11.\n");
 387 #endif
 388                         break;
 389                 case 't':
 390                         if (tty_flag)
 391                                 force_tty_flag = 1;
 392                         tty_flag = 1;
 393                         break;
 394                 case 'v':
 395                         if (debug_flag == 0) {
 396                                 debug_flag = 1;
 397                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 398                         } else {
 399                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 400                                         options.log_level++;
 401                                 break;
 402                         }
 403                         /* FALLTHROUGH */
 404                 case 'V':
 405                         fprintf(stderr, "%s, %s\n",
 406                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 407                         if (opt == 'V')
 408                                 exit(0);
 409                         break;
 410                 case 'w':
 411                         if (options.tun_open == -1)
 412                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 413                         options.tun_local = a2tun(optarg, &options.tun_remote);
 414                         if (options.tun_local == SSH_TUNID_ERR) {
 415                                 fprintf(stderr,
 416                                     "Bad tun device '%s'\n", optarg);
 417                                 exit(255);
 418                         }
 419                         break;
 420                 case 'W':
 421                         if (stdio_forward_host != NULL)
 422                                 fatal("stdio forward already specified");
 423                         if (muxclient_command != 0)
 424                                 fatal("Cannot specify stdio forward with -O");
 425                         if (parse_forward(&fwd, optarg, 1, 0)) {
 426                                 stdio_forward_host = fwd.listen_host;
 427                                 stdio_forward_port = fwd.listen_port;
 428                                 xfree(fwd.connect_host);
 429                         } else {
 430                                 fprintf(stderr,
 431                                     "Bad stdio forwarding specification '%s'\n",
 432                                     optarg);
 433                                 exit(255);
 434                         }
 435                         no_tty_flag = 1;
 436                         no_shell_flag = 1;
 437                         options.clear_forwardings = 1;
 438                         options.exit_on_forward_failure = 1;
 439                         break;
 440                 case 'q':
 441                         options.log_level = SYSLOG_LEVEL_QUIET;
 442                         break;
 443                 case 'e':
 444                         if (optarg[0] == '^' && optarg[2] == 0 &&
 445                             (u_char) optarg[1] >= 64 &&
 446                             (u_char) optarg[1] < 128)
 447                                 options.escape_char = (u_char) optarg[1] & 31;
 448                         else if (strlen(optarg) == 1)
 449                                 options.escape_char = (u_char) optarg[0];
 450                         else if (strcmp(optarg, "none") == 0)
 451                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 452                         else {
 453                                 fprintf(stderr, "Bad escape character '%s'.\n",
 454                                     optarg);
 455                                 exit(255);
 456                         }
 457                         break;
 458                 case 'c':
 459                         if (ciphers_valid(optarg)) {
 460                                 /* SSH2 only */
 461                                 options.ciphers = xstrdup(optarg);
 462                                 options.cipher = SSH_CIPHER_INVALID;
 463                         } else {
 464                                 /* SSH1 only */
 465                                 options.cipher = cipher_number(optarg);
 466                                 if (options.cipher == -1) {
 467                                         fprintf(stderr,
 468                                             "Unknown cipher type '%s'\n",
 469                                             optarg);
 470                                         exit(255);
 471                                 }
 472                                 if (options.cipher == SSH_CIPHER_3DES)
 473                                         options.ciphers = "3des-cbc";
 474                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 475                                         options.ciphers = "blowfish-cbc";
 476                                 else
 477                                         options.ciphers = (char *)-1;
 478                         }
 479                         break;
 480                 case 'm':
 481                         if (mac_valid(optarg))
 482                                 options.macs = xstrdup(optarg);
 483                         else {
 484                                 fprintf(stderr, "Unknown mac type '%s'\n",
 485                                     optarg);
 486                                 exit(255);
 487                         }
 488                         break;
 489                 case 'M':
 490                         if (options.control_master == SSHCTL_MASTER_YES)
 491                                 options.control_master = SSHCTL_MASTER_ASK;
 492                         else
 493                                 options.control_master = SSHCTL_MASTER_YES;
 494                         break;
 495                 case 'p':
 496                         options.port = a2port(optarg);
 497                         if (options.port <= 0) {
 498                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 499                                 exit(255);
 500                         }
 501                         break;
 502                 case 'l':
 503                         options.user = optarg;
 504                         break;
 505
 506                 case 'L':
 507                         if (parse_forward(&fwd, optarg, 0, 0))
 508                                 add_local_forward(&options, &fwd);
 509                         else {
 510                                 fprintf(stderr,
 511                                     "Bad local forwarding specification '%s'\n",
 512                                     optarg);
 513                                 exit(255);
 514                         }
 515                         break;
 516
 517                 case 'R':
 518                         if (parse_forward(&fwd, optarg, 0, 1)) {
 519                                 add_remote_forward(&options, &fwd);
 520                         } else {
 521                                 fprintf(stderr,
 522                                     "Bad remote forwarding specification "
 523                                     "'%s'\n", optarg);
 524                                 exit(255);
 525                         }
 526                         break;
 527
 528                 case 'D':
 529                         if (parse_forward(&fwd, optarg, 1, 0)) {
 530                                 add_local_forward(&options, &fwd);
 531                         } else {
 532                                 fprintf(stderr,
 533                                     "Bad dynamic forwarding specification "
 534                                     "'%s'\n", optarg);
 535                                 exit(255);
 536                         }
 537                         break;
 538
 539                 case 'C':
 540                         options.compression = 1;
 541                         break;
 542                 case 'N':
 543                         no_shell_flag = 1;
 544                         no_tty_flag = 1;
 545                         break;
 546                 case 'T':
 547                         no_tty_flag = 1;
 548                         break;
 549                 case 'o':
 550                         dummy = 1;
 551                         line = xstrdup(optarg);
 552                         if (process_config_line(&options, host ? host : "",
 553                             line, "command-line", 0, &dummy) != 0)
 554                                 exit(255);
 555                         xfree(line);
 556                         break;
 557                 case 's':
 558                         subsystem_flag = 1;
 559                         break;
 560                 case 'S':
 561                         if (options.control_path != NULL)
 562                                 free(options.control_path);
 563                         options.control_path = xstrdup(optarg);
 564                         break;
 565                 case 'b':
 566                         options.bind_address = optarg;
 567                         break;
 568                 case 'F':
 569                         config = optarg;
 570                         break;
 571                 default:
 572                         usage();
 573                 }
 574         }
 575
 576         ac -= optind;
 577         av += optind;
 578
 579         if (ac > 0 && !host) {
 580                 if (strrchr(*av, '@')) {
 581                         p = xstrdup(*av);
 582                         cp = strrchr(p, '@');
 583                         if (cp == NULL || cp == p)
 584                                 usage();
 585                         options.user = p;
 586                         *cp = '\0';
 587                         host = ++cp;
 588                 } else
 589                         host = *av;
 590                 if (ac > 1) {
 591                         optind = optreset = 1;
 592                         goto again;
 593                 }
 594                 ac--, av++;
 595         }
 596
 597         /* Check that we got a host name. */
 598         if (!host)
 599                 usage();
 600
 601         OpenSSL_add_all_algorithms();
 602         ERR_load_crypto_strings();
 603
 604         /* Initialize the command to execute on remote host. */
 605         buffer_init(&command);
 606
 607         /*
 608          * Save the command to execute on the remote host in a buffer. There
 609          * is no limit on the length of the command, except by the maximum
 610          * packet size.  Also sets the tty flag if there is no command.
 611          */
 612         if (!ac) {
 613                 /* No command specified - execute shell on a tty. */
 614                 tty_flag = 1;
 615                 if (subsystem_flag) {
 616                         fprintf(stderr,
 617                             "You must specify a subsystem to invoke.\n");
 618                         usage();
 619                 }
 620         } else {
 621                 /* A command has been specified.  Store it into the buffer. */
 622                 for (i = 0; i < ac; i++) {
 623                         if (i)
 624                                 buffer_append(&command, " ", 1);
 625                         buffer_append(&command, av[i], strlen(av[i]));
 626                 }
 627         }
 628
 629         /* Cannot fork to background if no command. */
 630         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 631             !no_shell_flag)
 632                 fatal("Cannot fork into background without a command "
 633                     "to execute.");
 634
 635         /* Allocate a tty by default if no command specified. */
 636         if (buffer_len(&command) == 0)
 637                 tty_flag = 1;
 638
 639         /* Force no tty */
 640         if (no_tty_flag || muxclient_command != 0)
 641                 tty_flag = 0;
 642         /* Do not allocate a tty if stdin is not a tty. */
 643         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 644                 if (tty_flag)
 645                         logit("Pseudo-terminal will not be allocated because "
 646                             "stdin is not a terminal.");
 647                 tty_flag = 0;
 648         }
 649
 650         /*
 651          * Initialize "log" output.  Since we are the client all output
 652          * actually goes to stderr.
 653          */
 654         log_init(argv0,
 655             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 656             SYSLOG_FACILITY_USER, !use_syslog);
 657
 658         /*
 659          * Read per-user configuration file.  Ignore the system wide config
 660          * file if the user specifies a config file on the command line.
 661          */
 662         if (config != NULL) {
 663                 if (!read_config_file(config, host, &options, 0))
 664                         fatal("Can't open user config file %.100s: "
 665                             "%.100s", config, strerror(errno));
 666         } else {
 667                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 668                     _PATH_SSH_USER_CONFFILE);
 669                 if (r > 0 && (size_t)r < sizeof(buf))
 670                         (void)read_config_file(buf, host, &options, 1);
 671
 672                 /* Read systemwide configuration file after use config. */
 673                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 674                     &options, 0);
 675         }
 676
 677         /* Fill configuration defaults. */
 678         fill_default_options(&options);
 679
 680         channel_set_af(options.address_family);
 681
 682         /* reinit */
 683         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 684
 685         seed_rng();
 686
 687         if (options.user == NULL)
 688                 options.user = xstrdup(pw->pw_name);
 689
 690         /* Get default port if port has not been set. */
 691         if (options.port == 0) {
 692                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 693                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 694         }
 695
 696         /* preserve host name given on command line for %n expansion */
 697         host_arg = host;
 698         if (options.hostname != NULL) {
 699                 host = percent_expand(options.hostname,
 700                     "h", host, (char *)NULL);
 701         }
 702
 703         if (options.local_command != NULL) {
 704                 char thishost[NI_MAXHOST];
 705
 706                 if (gethostname(thishost, sizeof(thishost)) == -1)
 707                         fatal("gethostname: %s", strerror(errno));
 708                 snprintf(buf, sizeof(buf), "%d", options.port);
 709                 debug3("expanding LocalCommand: %s", options.local_command);
 710                 cp = options.local_command;
 711                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 712                     "h", host, "l", thishost, "n", host_arg, "r", options.user,
 713                     "p", buf, "u", pw->pw_name, (char *)NULL);
 714                 debug3("expanded LocalCommand: %s", options.local_command);
 715                 xfree(cp);
 716         }
 717
 718         /* force lowercase for hostkey matching */
 719         if (options.host_key_alias != NULL) {
 720                 for (p = options.host_key_alias; *p; p++)
 721                         if (isupper(*p))
 722                                 *p = (char)tolower(*p);
 723         }
 724
 725         if (options.proxy_command != NULL &&
 726             strcmp(options.proxy_command, "none") == 0) {
 727                 xfree(options.proxy_command);
 728                 options.proxy_command = NULL;
 729         }
 730         if (options.control_path != NULL &&
 731             strcmp(options.control_path, "none") == 0) {
 732                 xfree(options.control_path);
 733                 options.control_path = NULL;
 734         }
 735
 736         if (options.control_path != NULL) {
 737                 char thishost[NI_MAXHOST];
 738
 739                 if (gethostname(thishost, sizeof(thishost)) == -1)
 740                         fatal("gethostname: %s", strerror(errno));
 741                 snprintf(buf, sizeof(buf), "%d", options.port);
 742                 cp = tilde_expand_filename(options.control_path,
 743                     original_real_uid);
 744                 xfree(options.control_path);
 745                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 746                     "r", options.user, "l", thishost, (char *)NULL);
 747                 xfree(cp);
 748         }
 749         if (muxclient_command != 0 && options.control_path == NULL)
 750                 fatal("No ControlPath specified for \"-O\" command");
 751         if (options.control_path != NULL)
 752                 muxclient(options.control_path);
 753
 754         timeout_ms = options.connection_timeout * 1000;
 755
 756         /* Open a connection to the remote host. */
 757         if (ssh_connect(host, &hostaddr, options.port,
 758             options.address_family, options.connection_attempts, &timeout_ms,
 759             options.tcp_keep_alive,
 760 #ifdef HAVE_CYGWIN
 761             options.use_privileged_port,
 762 #else
 763             original_effective_uid == 0 && options.use_privileged_port,
 764 #endif
 765             options.proxy_command) != 0)
 766                 exit(255);
 767
 768         if (timeout_ms > 0)
 769                 debug3("timeout: %d ms remain after connect", timeout_ms);
 770
 771         /*
 772          * If we successfully made the connection, load the host private key
 773          * in case we will need it later for combined rsa-rhosts
 774          * authentication. This must be done before releasing extra
 775          * privileges, because the file is only readable by root.
 776          * If we cannot access the private keys, load the public keys
 777          * instead and try to execute the ssh-keysign helper instead.
 778          */
 779         sensitive_data.nkeys = 0;
 780         sensitive_data.keys = NULL;
 781         sensitive_data.external_keysign = 0;
 782         if (options.rhosts_rsa_authentication ||
 783             options.hostbased_authentication) {
 784                 sensitive_data.nkeys = 7;
 785                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 786                     sizeof(Key));
 787                 for (i = 0; i < sensitive_data.nkeys; i++)
 788                         sensitive_data.keys[i] = NULL;
 789
 790                 PRIV_START;
 791                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 792                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 793                 sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
 794                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 795 #ifdef OPENSSL_HAS_ECC
 796                 sensitive_data.keys[2] = key_load_private_cert(KEY_ECDSA,
 797                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
 798 #endif
 799                 sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
 800                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 801                 sensitive_data.keys[4] = key_load_private_type(KEY_DSA,
 802                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 803 #ifdef OPENSSL_HAS_ECC
 804                 sensitive_data.keys[5] = key_load_private_type(KEY_ECDSA,
 805                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
 806 #endif
 807                 sensitive_data.keys[6] = key_load_private_type(KEY_RSA,
 808                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 809                 PRIV_END;
 810
 811                 if (options.hostbased_authentication == 1 &&
 812                     sensitive_data.keys[0] == NULL &&
 813                     sensitive_data.keys[4] == NULL &&
 814                     sensitive_data.keys[5] == NULL &&
 815                     sensitive_data.keys[6] == NULL) {
 816                         sensitive_data.keys[1] = key_load_cert(
 817                             _PATH_HOST_DSA_KEY_FILE);
 818 #ifdef OPENSSL_HAS_ECC
 819                         sensitive_data.keys[2] = key_load_cert(
 820                             _PATH_HOST_ECDSA_KEY_FILE);
 821 #endif
 822                         sensitive_data.keys[3] = key_load_cert(
 823                             _PATH_HOST_RSA_KEY_FILE);
 824                         sensitive_data.keys[4] = key_load_public(
 825                             _PATH_HOST_DSA_KEY_FILE, NULL);
 826 #ifdef OPENSSL_HAS_ECC
 827                         sensitive_data.keys[5] = key_load_public(
 828                             _PATH_HOST_ECDSA_KEY_FILE, NULL);
 829 #endif
 830                         sensitive_data.keys[6] = key_load_public(
 831                             _PATH_HOST_RSA_KEY_FILE, NULL);
 832                         sensitive_data.external_keysign = 1;
 833                 }
 834         }
 835         /*
 836          * Get rid of any extra privileges that we may have.  We will no
 837          * longer need them.  Also, extra privileges could make it very hard
 838          * to read identity files and other non-world-readable files from the
 839          * user's home directory if it happens to be on a NFS volume where
 840          * root is mapped to nobody.
 841          */
 842         if (original_effective_uid == 0) {
 843                 PRIV_START;
 844                 permanently_set_uid(pw);
 845         }
 846
 847         /*
 848          * Now that we are back to our own permissions, create ~/.ssh
 849          * directory if it doesn't already exist.
 850          */
 851         r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
 852             strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 853         if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
 854 #ifdef WITH_SELINUX
 855                 ssh_selinux_setfscreatecon(buf);
 856 #endif
 857                 if (mkdir(buf, 0700) < 0)
 858                         error("Could not create directory '%.200s'.", buf);
 859 #ifdef WITH_SELINUX
 860                 ssh_selinux_setfscreatecon(NULL);
 861 #endif
 862         }
 863         /* load options.identity_files */
 864         load_public_identity_files();
 865
 866         /* Expand ~ in known host file names. */
 867         /* XXX mem-leaks: */
 868         options.system_hostfile =
 869             tilde_expand_filename(options.system_hostfile, original_real_uid);
 870         options.user_hostfile =
 871             tilde_expand_filename(options.user_hostfile, original_real_uid);
 872         options.system_hostfile2 =
 873             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 874         options.user_hostfile2 =
 875             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 876
 877         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 878         signal(SIGCHLD, main_sigchld_handler);
 879
 880         /* Log into the remote system.  Never returns if the login fails. */
 881         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 882             options.port, pw, timeout_ms);
 883
 884         if (packet_connection_is_on_socket()) {
 885                 verbose("Authenticated to %s ([%s]:%d).", host,
 886                     get_remote_ipaddr(), get_remote_port());
 887         } else {
 888                 verbose("Authenticated to %s (via proxy).", host);
 889         }
 890
 891         /* We no longer need the private host keys.  Clear them now. */
 892         if (sensitive_data.nkeys != 0) {
 893                 for (i = 0; i < sensitive_data.nkeys; i++) {
 894                         if (sensitive_data.keys[i] != NULL) {
 895                                 /* Destroys contents safely */
 896                                 debug3("clear hostkey %d", i);
 897                                 key_free(sensitive_data.keys[i]);
 898                                 sensitive_data.keys[i] = NULL;
 899                         }
 900                 }
 901                 xfree(sensitive_data.keys);
 902         }
 903         for (i = 0; i < options.num_identity_files; i++) {
 904                 if (options.identity_files[i]) {
 905                         xfree(options.identity_files[i]);
 906                         options.identity_files[i] = NULL;
 907                 }
 908                 if (options.identity_keys[i]) {
 909                         key_free(options.identity_keys[i]);
 910                         options.identity_keys[i] = NULL;
 911                 }
 912         }
 913
 914         exit_status = compat20 ? ssh_session2() : ssh_session();
 915         packet_close();
 916
 917         if (options.control_path != NULL && muxserver_sock != -1)
 918                 unlink(options.control_path);
 919
 920         /* Kill ProxyCommand if it is running. */
 921         ssh_kill_proxy_command();
 922
 923         return exit_status;
 924 }
 925
 926 static void
 927 control_persist_detach(void)
 928 {
 929         pid_t pid;
 930         int devnull;
 931
 932         debug("%s: backgrounding master process", __func__);
 933
 934         /*
 935          * master (current process) into the background, and make the
 936          * foreground process a client of the backgrounded master.
 937          */
 938         switch ((pid = fork())) {
 939         case -1:
 940                 fatal("%s: fork: %s", __func__, strerror(errno));
 941         case 0:
 942                 /* Child: master process continues mainloop */
 943                 break;
 944         default:
 945                 /* Parent: set up mux slave to connect to backgrounded master */
 946                 debug2("%s: background process is %ld", __func__, (long)pid);
 947                 stdin_null_flag = ostdin_null_flag;
 948                 no_shell_flag = ono_shell_flag;
 949                 no_tty_flag = ono_tty_flag;
 950                 tty_flag = otty_flag;
 951                 close(muxserver_sock);
 952                 muxserver_sock = -1;
 953                 options.control_master = SSHCTL_MASTER_NO;
 954                 muxclient(options.control_path);
 955                 /* muxclient() doesn't return on success. */
 956                 fatal("Failed to connect to new control master");
 957         }
 958         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
 959                 error("%s: open(\"/dev/null\"): %s", __func__,
 960                     strerror(errno));
 961         } else {
 962                 if (dup2(devnull, STDIN_FILENO) == -1 ||
 963                     dup2(devnull, STDOUT_FILENO) == -1)
 964                         error("%s: dup2: %s", __func__, strerror(errno));
 965                 if (devnull > STDERR_FILENO)
 966                         close(devnull);
 967         }
 968 }
 969
 970 /* Do fork() after authentication. Used by "ssh -f" */
 971 static void
 972 fork_postauth(void)
 973 {
 974         if (need_controlpersist_detach)
 975                 control_persist_detach();
 976         debug("forking to background");
 977         fork_after_authentication_flag = 0;
 978         if (daemon(1, 1) < 0)
 979                 fatal("daemon() failed: %.200s", strerror(errno));
 980 }
 981
 982 /* Callback for remote forward global requests */
 983 static void
 984 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 985 {
 986         Forward *rfwd = (Forward *)ctxt;
 987
 988         /* XXX verbose() on failure? */
 989         debug("remote forward %s for: listen %d, connect %s:%d",
 990             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
 991             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
 992         if (type == SSH2_MSG_REQUEST_SUCCESS && rfwd->listen_port == 0) {
 993                 rfwd->allocated_port = packet_get_int();
 994                 logit("Allocated port %u for remote forward to %s:%d",
 995                     rfwd->allocated_port,
 996                     rfwd->connect_host, rfwd->connect_port);
 997         }
 998
 999         if (type == SSH2_MSG_REQUEST_FAILURE) {
1000                 if (options.exit_on_forward_failure)
1001                         fatal("Error: remote port forwarding failed for "
1002                             "listen port %d", rfwd->listen_port);
1003                 else
1004                         logit("Warning: remote port forwarding failed for "
1005                             "listen port %d", rfwd->listen_port);
1006         }
1007         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1008                 debug("All remote forwarding requests processed");
1009                 if (fork_after_authentication_flag)
1010                         fork_postauth();
1011         }
1012 }
1013
1014 static void
1015 client_cleanup_stdio_fwd(int id, void *arg)
1016 {
1017         debug("stdio forwarding: done");
1018         cleanup_exit(0);
1019 }
1020
1021 static int
1022 client_setup_stdio_fwd(const char *host_to_connect, u_short port_to_connect)
1023 {
1024         Channel *c;
1025         int in, out;
1026
1027         debug3("client_setup_stdio_fwd %s:%d", host_to_connect,
1028             port_to_connect);
1029
1030         in = dup(STDIN_FILENO);
1031         out = dup(STDOUT_FILENO);
1032         if (in < 0 || out < 0)
1033                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1034
1035         if ((c = channel_connect_stdio_fwd(host_to_connect, port_to_connect,
1036             in, out)) == NULL)
1037                 return 0;
1038         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1039         return 1;
1040 }
1041
1042 static void
1043 ssh_init_forwarding(void)
1044 {
1045         int success = 0;
1046         int i;
1047
1048         if (stdio_forward_host != NULL) {
1049                 if (!compat20) {
1050                         fatal("stdio forwarding require Protocol 2");
1051                 }
1052                 if (!client_setup_stdio_fwd(stdio_forward_host,
1053                     stdio_forward_port))
1054                         fatal("Failed to connect in stdio forward mode.");
1055         }
1056
1057         /* Initiate local TCP/IP port forwardings. */
1058         for (i = 0; i < options.num_local_forwards; i++) {
1059                 debug("Local connections to %.200s:%d forwarded to remote "
1060                     "address %.200s:%d",
1061                     (options.local_forwards[i].listen_host == NULL) ?
1062                     (options.gateway_ports ? "*" : "LOCALHOST") :
1063                     options.local_forwards[i].listen_host,
1064                     options.local_forwards[i].listen_port,
1065                     options.local_forwards[i].connect_host,
1066                     options.local_forwards[i].connect_port);
1067                 success += channel_setup_local_fwd_listener(
1068                     options.local_forwards[i].listen_host,
1069                     options.local_forwards[i].listen_port,
1070                     options.local_forwards[i].connect_host,
1071                     options.local_forwards[i].connect_port,
1072                     options.gateway_ports);
1073         }
1074         if (i > 0 && success != i && options.exit_on_forward_failure)
1075                 fatal("Could not request local forwarding.");
1076         if (i > 0 && success == 0)
1077                 error("Could not request local forwarding.");
1078
1079         /* Initiate remote TCP/IP port forwardings. */
1080         for (i = 0; i < options.num_remote_forwards; i++) {
1081                 debug("Remote connections from %.200s:%d forwarded to "
1082                     "local address %.200s:%d",
1083                     (options.remote_forwards[i].listen_host == NULL) ?
1084                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1085                     options.remote_forwards[i].listen_port,
1086                     options.remote_forwards[i].connect_host,
1087                     options.remote_forwards[i].connect_port);
1088                 if (channel_request_remote_forwarding(
1089                     options.remote_forwards[i].listen_host,
1090                     options.remote_forwards[i].listen_port,
1091                     options.remote_forwards[i].connect_host,
1092                     options.remote_forwards[i].connect_port) < 0) {
1093                         if (options.exit_on_forward_failure)
1094                                 fatal("Could not request remote forwarding.");
1095                         else
1096                                 logit("Warning: Could not request remote "
1097                                     "forwarding.");
1098                 }
1099                 client_register_global_confirm(ssh_confirm_remote_forward,
1100                     &options.remote_forwards[i]);
1101         }
1102
1103         /* Initiate tunnel forwarding. */
1104         if (options.tun_open != SSH_TUNMODE_NO) {
1105                 if (client_request_tun_fwd(options.tun_open,
1106                     options.tun_local, options.tun_remote) == -1) {
1107                         if (options.exit_on_forward_failure)
1108                                 fatal("Could not request tunnel forwarding.");
1109                         else
1110                                 error("Could not request tunnel forwarding.");
1111                 }
1112         }
1113 }
1114
1115 static void
1116 check_agent_present(void)
1117 {
1118         if (options.forward_agent) {
1119                 /* Clear agent forwarding if we don't have an agent. */
1120                 if (!ssh_agent_present())
1121                         options.forward_agent = 0;
1122         }
1123 }
1124
1125 static int
1126 ssh_session(void)
1127 {
1128         int type;
1129         int interactive = 0;
1130         int have_tty = 0;
1131         struct winsize ws;
1132         char *cp;
1133         const char *display;
1134
1135         /* Enable compression if requested. */
1136         if (options.compression) {
1137                 debug("Requesting compression at level %d.",
1138                     options.compression_level);
1139
1140                 if (options.compression_level < 1 ||
1141                     options.compression_level > 9)
1142                         fatal("Compression level must be from 1 (fast) to "
1143                             "9 (slow, best).");
1144
1145                 /* Send the request. */
1146                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1147                 packet_put_int(options.compression_level);
1148                 packet_send();
1149                 packet_write_wait();
1150                 type = packet_read();
1151                 if (type == SSH_SMSG_SUCCESS)
1152                         packet_start_compression(options.compression_level);
1153                 else if (type == SSH_SMSG_FAILURE)
1154                         logit("Warning: Remote host refused compression.");
1155                 else
1156                         packet_disconnect("Protocol error waiting for "
1157                             "compression response.");
1158         }
1159         /* Allocate a pseudo tty if appropriate. */
1160         if (tty_flag) {
1161                 debug("Requesting pty.");
1162
1163                 /* Start the packet. */
1164                 packet_start(SSH_CMSG_REQUEST_PTY);
1165
1166                 /* Store TERM in the packet.  There is no limit on the
1167                    length of the string. */
1168                 cp = getenv("TERM");
1169                 if (!cp)
1170                         cp = "";
1171                 packet_put_cstring(cp);
1172
1173                 /* Store window size in the packet. */
1174                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1175                         memset(&ws, 0, sizeof(ws));
1176                 packet_put_int((u_int)ws.ws_row);
1177                 packet_put_int((u_int)ws.ws_col);
1178                 packet_put_int((u_int)ws.ws_xpixel);
1179                 packet_put_int((u_int)ws.ws_ypixel);
1180
1181                 /* Store tty modes in the packet. */
1182                 tty_make_modes(fileno(stdin), NULL);
1183
1184                 /* Send the packet, and wait for it to leave. */
1185                 packet_send();
1186                 packet_write_wait();
1187
1188                 /* Read response from the server. */
1189                 type = packet_read();
1190                 if (type == SSH_SMSG_SUCCESS) {
1191                         interactive = 1;
1192                         have_tty = 1;
1193                 } else if (type == SSH_SMSG_FAILURE)
1194                         logit("Warning: Remote host failed or refused to "
1195                             "allocate a pseudo tty.");
1196                 else
1197                         packet_disconnect("Protocol error waiting for pty "
1198                             "request response.");
1199         }
1200         /* Request X11 forwarding if enabled and DISPLAY is set. */
1201         display = getenv("DISPLAY");
1202         if (options.forward_x11 && display != NULL) {
1203                 char *proto, *data;
1204                 /* Get reasonable local authentication information. */
1205                 client_x11_get_proto(display, options.xauth_location,
1206                     options.forward_x11_trusted,
1207                     options.forward_x11_timeout,
1208                     &proto, &data);
1209                 /* Request forwarding with authentication spoofing. */
1210                 debug("Requesting X11 forwarding with authentication "
1211                     "spoofing.");
1212                 x11_request_forwarding_with_spoofing(0, display, proto, data);
1213
1214                 /* Read response from the server. */
1215                 type = packet_read();
1216                 if (type == SSH_SMSG_SUCCESS) {
1217                         interactive = 1;
1218                 } else if (type == SSH_SMSG_FAILURE) {
1219                         logit("Warning: Remote host denied X11 forwarding.");
1220                 } else {
1221                         packet_disconnect("Protocol error waiting for X11 "
1222                             "forwarding");
1223                 }
1224         }
1225         /* Tell the packet module whether this is an interactive session. */
1226         packet_set_interactive(interactive,
1227             options.ip_qos_interactive, options.ip_qos_bulk);
1228
1229         /* Request authentication agent forwarding if appropriate. */
1230         check_agent_present();
1231
1232         if (options.forward_agent) {
1233                 debug("Requesting authentication agent forwarding.");
1234                 auth_request_forwarding();
1235
1236                 /* Read response from the server. */
1237                 type = packet_read();
1238                 packet_check_eom();
1239                 if (type != SSH_SMSG_SUCCESS)
1240                         logit("Warning: Remote host denied authentication agent forwarding.");
1241         }
1242
1243         /* Initiate port forwardings. */
1244         ssh_init_forwarding();
1245
1246         /* Execute a local command */
1247         if (options.local_command != NULL &&
1248             options.permit_local_command)
1249                 ssh_local_cmd(options.local_command);
1250
1251         /*
1252          * If requested and we are not interested in replies to remote
1253          * forwarding requests, then let ssh continue in the background.
1254          */
1255         if (fork_after_authentication_flag) {
1256                 if (options.exit_on_forward_failure &&
1257                     options.num_remote_forwards > 0) {
1258                         debug("deferring postauth fork until remote forward "
1259                             "confirmation received");
1260                 } else
1261                         fork_postauth();
1262         }
1263
1264         /*
1265          * If a command was specified on the command line, execute the
1266          * command now. Otherwise request the server to start a shell.
1267          */
1268         if (buffer_len(&command) > 0) {
1269                 int len = buffer_len(&command);
1270                 if (len > 900)
1271                         len = 900;
1272                 debug("Sending command: %.*s", len,
1273                     (u_char *)buffer_ptr(&command));
1274                 packet_start(SSH_CMSG_EXEC_CMD);
1275                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1276                 packet_send();
1277                 packet_write_wait();
1278         } else {
1279                 debug("Requesting shell.");
1280                 packet_start(SSH_CMSG_EXEC_SHELL);
1281                 packet_send();
1282                 packet_write_wait();
1283         }
1284
1285         /* Enter the interactive session. */
1286         return client_loop(have_tty, tty_flag ?
1287             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1288 }
1289
1290 /* request pty/x11/agent/tcpfwd/shell for channel */
1291 static void
1292 ssh_session2_setup(int id, int success, void *arg)
1293 {
1294         extern char **environ;
1295         const char *display;
1296         int interactive = tty_flag;
1297
1298         if (!success)
1299                 return; /* No need for error message, channels code sens one */
1300
1301         display = getenv("DISPLAY");
1302         if (options.forward_x11 && display != NULL) {
1303                 char *proto, *data;
1304                 /* Get reasonable local authentication information. */
1305                 client_x11_get_proto(display, options.xauth_location,
1306                     options.forward_x11_trusted,
1307                     options.forward_x11_timeout, &proto, &data);
1308                 /* Request forwarding with authentication spoofing. */
1309                 debug("Requesting X11 forwarding with authentication "
1310                     "spoofing.");
1311                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1312                 interactive = 1;
1313                 /* XXX wait for reply */
1314         }
1315
1316         check_agent_present();
1317         if (options.forward_agent) {
1318                 debug("Requesting authentication agent forwarding.");
1319                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1320                 packet_send();
1321         }
1322
1323         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1324             NULL, fileno(stdin), &command, environ);
1325 }
1326
1327 /* open new channel for a session */
1328 static int
1329 ssh_session2_open(void)
1330 {
1331         Channel *c;
1332         int window, packetmax, in, out, err;
1333
1334         if (stdin_null_flag) {
1335                 in = open(_PATH_DEVNULL, O_RDONLY);
1336         } else {
1337                 in = dup(STDIN_FILENO);
1338         }
1339         out = dup(STDOUT_FILENO);
1340         err = dup(STDERR_FILENO);
1341
1342         if (in < 0 || out < 0 || err < 0)
1343                 fatal("dup() in/out/err failed");
1344
1345         /* enable nonblocking unless tty */
1346         if (!isatty(in))
1347                 set_nonblock(in);
1348         if (!isatty(out))
1349                 set_nonblock(out);
1350         if (!isatty(err))
1351                 set_nonblock(err);
1352
1353         window = CHAN_SES_WINDOW_DEFAULT;
1354         packetmax = CHAN_SES_PACKET_DEFAULT;
1355         if (tty_flag) {
1356                 window >>= 1;
1357                 packetmax >>= 1;
1358         }
1359         c = channel_new(
1360             "session", SSH_CHANNEL_OPENING, in, out, err,
1361             window, packetmax, CHAN_EXTENDED_WRITE,
1362             "client-session", /*nonblock*/0);
1363
1364         debug3("ssh_session2_open: channel_new: %d", c->self);
1365
1366         channel_send_open(c->self);
1367         if (!no_shell_flag)
1368                 channel_register_open_confirm(c->self,
1369                     ssh_session2_setup, NULL);
1370
1371         return c->self;
1372 }
1373
1374 static int
1375 ssh_session2(void)
1376 {
1377         int id = -1;
1378
1379         /* XXX should be pre-session */
1380         ssh_init_forwarding();
1381
1382         /* Start listening for multiplex clients */
1383         muxserver_listen();
1384
1385         /*
1386          * If we are in control persist mode, then prepare to background
1387          * ourselves and have a foreground client attach as a control
1388          * slave. NB. we must save copies of the flags that we override for
1389          * the backgrounding, since we defer attachment of the slave until
1390          * after the connection is fully established (in particular,
1391          * async rfwd replies have been received for ExitOnForwardFailure).
1392          */
1393         if (options.control_persist && muxserver_sock != -1) {
1394                 ostdin_null_flag = stdin_null_flag;
1395                 ono_shell_flag = no_shell_flag;
1396                 ono_tty_flag = no_tty_flag;
1397                 otty_flag = tty_flag;
1398                 stdin_null_flag = 1;
1399                 no_shell_flag = 1;
1400                 no_tty_flag = 1;
1401                 tty_flag = 0;
1402                 if (!fork_after_authentication_flag)
1403                         need_controlpersist_detach = 1;
1404                 fork_after_authentication_flag = 1;
1405         }
1406
1407         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1408                 id = ssh_session2_open();
1409
1410         /* If we don't expect to open a new session, then disallow it */
1411         if (options.control_master == SSHCTL_MASTER_NO &&
1412             (datafellows & SSH_NEW_OPENSSH)) {
1413                 debug("Requesting no-more-sessions@openssh.com");
1414                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1415                 packet_put_cstring("no-more-sessions@openssh.com");
1416                 packet_put_char(0);
1417                 packet_send();
1418         }
1419
1420         /* Execute a local command */
1421         if (options.local_command != NULL &&
1422             options.permit_local_command)
1423                 ssh_local_cmd(options.local_command);
1424
1425         /*
1426          * If requested and we are not interested in replies to remote
1427          * forwarding requests, then let ssh continue in the background.
1428          */
1429         if (fork_after_authentication_flag) {
1430                 if (options.exit_on_forward_failure &&
1431                     options.num_remote_forwards > 0) {
1432                         debug("deferring postauth fork until remote forward "
1433                             "confirmation received");
1434                 } else
1435                         fork_postauth();
1436         }
1437
1438         if (options.use_roaming)
1439                 request_roaming();
1440
1441         return client_loop(tty_flag, tty_flag ?
1442             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1443 }
1444
1445 static void
1446 load_public_identity_files(void)
1447 {
1448         char *filename, *cp, thishost[NI_MAXHOST];
1449         char *pwdir = NULL, *pwname = NULL;
1450         int i = 0;
1451         Key *public;
1452         struct passwd *pw;
1453         u_int n_ids;
1454         char *identity_files[SSH_MAX_IDENTITY_FILES];
1455         Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1456 #ifdef ENABLE_PKCS11
1457         Key **keys;
1458         int nkeys;
1459 #endif /* PKCS11 */
1460
1461         n_ids = 0;
1462         bzero(identity_files, sizeof(identity_files));
1463         bzero(identity_keys, sizeof(identity_keys));
1464
1465 #ifdef ENABLE_PKCS11
1466         if (options.pkcs11_provider != NULL &&
1467             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1468             (pkcs11_init(!options.batch_mode) == 0) &&
1469             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1470             &keys)) > 0) {
1471                 for (i = 0; i < nkeys; i++) {
1472                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1473                                 key_free(keys[i]);
1474                                 continue;
1475                         }
1476                         identity_keys[n_ids] = keys[i];
1477                         identity_files[n_ids] =
1478                             xstrdup(options.pkcs11_provider); /* XXX */
1479                         n_ids++;
1480                 }
1481                 xfree(keys);
1482         }
1483 #endif /* ENABLE_PKCS11 */
1484         if ((pw = getpwuid(original_real_uid)) == NULL)
1485                 fatal("load_public_identity_files: getpwuid failed");
1486         pwname = xstrdup(pw->pw_name);
1487         pwdir = xstrdup(pw->pw_dir);
1488         if (gethostname(thishost, sizeof(thishost)) == -1)
1489                 fatal("load_public_identity_files: gethostname: %s",
1490                     strerror(errno));
1491         for (i = 0; i < options.num_identity_files; i++) {
1492                 if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1493                         xfree(options.identity_files[i]);
1494                         continue;
1495                 }
1496                 cp = tilde_expand_filename(options.identity_files[i],
1497                     original_real_uid);
1498                 filename = percent_expand(cp, "d", pwdir,
1499                     "u", pwname, "l", thishost, "h", host,
1500                     "r", options.user, (char *)NULL);
1501                 xfree(cp);
1502                 public = key_load_public(filename, NULL);
1503                 debug("identity file %s type %d", filename,
1504                     public ? public->type : -1);
1505                 xfree(options.identity_files[i]);
1506                 identity_files[n_ids] = filename;
1507                 identity_keys[n_ids] = public;
1508
1509                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
1510                         continue;
1511
1512                 /* Try to add the certificate variant too */
1513                 xasprintf(&cp, "%s-cert", filename);
1514                 public = key_load_public(cp, NULL);
1515                 debug("identity file %s type %d", cp,
1516                     public ? public->type : -1);
1517                 if (public == NULL) {
1518                         xfree(cp);
1519                         continue;
1520                 }
1521                 if (!key_is_cert(public)) {
1522                         debug("%s: key %s type %s is not a certificate",
1523                             __func__, cp, key_type(public));
1524                         key_free(public);
1525                         xfree(cp);
1526                         continue;
1527                 }
1528                 identity_keys[n_ids] = public;
1529                 /* point to the original path, most likely the private key */
1530                 identity_files[n_ids] = xstrdup(filename);
1531                 n_ids++;
1532         }
1533         options.num_identity_files = n_ids;
1534         memcpy(options.identity_files, identity_files, sizeof(identity_files));
1535         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
1536
1537         bzero(pwname, strlen(pwname));
1538         xfree(pwname);
1539         bzero(pwdir, strlen(pwdir));
1540         xfree(pwdir);
1541 }
1542
1543 static void
1544 main_sigchld_handler(int sig)
1545 {
1546         int save_errno = errno;
1547         pid_t pid;
1548         int status;
1549
1550         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
1551             (pid < 0 && errno == EINTR))
1552                 ;
1553
1554         signal(sig, main_sigchld_handler);
1555         errno = save_errno;
1556 }
1557