crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.364 2011/08/02 23:15:03 djm Exp $ */
   2 /* $FreeBSD$ */
   3 /*
   4  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   5  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   6  *                    All rights reserved
   7  * Ssh client program.  This program can be used to log into a remote machine.
   8  * The software supports strong authentication, encryption, and forwarding
   9  * of X11, TCP/IP, and authentication connections.
  10  *
  11  * As far as I am concerned, the code I have written for this software
  12  * can be used freely for any purpose.  Any derived versions of this
  13  * software must be clearly marked as such, and if the derived work is
  14  * incompatible with the protocol description in the RFC file, it must be
  15  * called by a name other than "ssh" or "Secure Shell".
  16  *
  17  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  18  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  19  *
  20  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  21  * in Canada (German citizen).
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the above copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  *
  32  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  33  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  34  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  35  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  36  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  37  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  38  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  39  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  40  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  41  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  42  */
  43
  44 #include "includes.h"
  45 __RCSID("$FreeBSD$");
  46
  47 #include <sys/types.h>
  48 #ifdef HAVE_SYS_STAT_H
  49 # include <sys/stat.h>
  50 #endif
  51 #include <sys/resource.h>
  52 #include <sys/ioctl.h>
  53 #include <sys/param.h>
  54 #include <sys/socket.h>
  55 #include <sys/wait.h>
  56
  57 #include <ctype.h>
  58 #include <errno.h>
  59 #include <fcntl.h>
  60 #include <netdb.h>
  61 #ifdef HAVE_PATHS_H
  62 #include <paths.h>
  63 #endif
  64 #include <pwd.h>
  65 #include <signal.h>
  66 #include <stdarg.h>
  67 #include <stddef.h>
  68 #include <stdio.h>
  69 #include <stdlib.h>
  70 #include <string.h>
  71 #include <unistd.h>
  72
  73 #include <netinet/in.h>
  74 #include <arpa/inet.h>
  75
  76 #include <openssl/evp.h>
  77 #include <openssl/err.h>
  78 #include "openbsd-compat/openssl-compat.h"
  79 #include "openbsd-compat/sys-queue.h"
  80
  81 #include "xmalloc.h"
  82 #include "ssh.h"
  83 #include "ssh1.h"
  84 #include "ssh2.h"
  85 #include "canohost.h"
  86 #include "compat.h"
  87 #include "cipher.h"
  88 #include "packet.h"
  89 #include "buffer.h"
  90 #include "channels.h"
  91 #include "key.h"
  92 #include "authfd.h"
  93 #include "authfile.h"
  94 #include "pathnames.h"
  95 #include "dispatch.h"
  96 #include "clientloop.h"
  97 #include "log.h"
  98 #include "readconf.h"
  99 #include "sshconnect.h"
 100 #include "misc.h"
 101 #include "kex.h"
 102 #include "mac.h"
 103 #include "sshpty.h"
 104 #include "match.h"
 105 #include "msg.h"
 106 #include "uidswap.h"
 107 #include "roaming.h"
 108 #include "version.h"
 109
 110 #ifdef ENABLE_PKCS11
 111 #include "ssh-pkcs11.h"
 112 #endif
 113
 114 extern char *__progname;
 115
 116 /* Saves a copy of argv for setproctitle emulation */
 117 #ifndef HAVE_SETPROCTITLE
 118 static char **saved_av;
 119 #endif
 120
 121 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 122 int debug_flag = 0;
 123
 124 /* Flag indicating whether a tty should be requested */
 125 int tty_flag = 0;
 126
 127 /* don't exec a shell */
 128 int no_shell_flag = 0;
 129
 130 /*
 131  * Flag indicating that nothing should be read from stdin.  This can be set
 132  * on the command line.
 133  */
 134 int stdin_null_flag = 0;
 135
 136 /*
 137  * Flag indicating that the current process should be backgrounded and
 138  * a new slave launched in the foreground for ControlPersist.
 139  */
 140 int need_controlpersist_detach = 0;
 141
 142 /* Copies of flags for ControlPersist foreground slave */
 143 int ostdin_null_flag, ono_shell_flag, otty_flag, orequest_tty;
 144
 145 /*
 146  * Flag indicating that ssh should fork after authentication.  This is useful
 147  * so that the passphrase can be entered manually, and then ssh goes to the
 148  * background.
 149  */
 150 int fork_after_authentication_flag = 0;
 151
 152 /* forward stdio to remote host and port */
 153 char *stdio_forward_host = NULL;
 154 int stdio_forward_port = 0;
 155
 156 /*
 157  * General data structure for command line options and options configurable
 158  * in configuration files.  See readconf.h.
 159  */
 160 Options options;
 161
 162 /* optional user configfile */
 163 char *config = NULL;
 164
 165 /*
 166  * Name of the host we are connecting to.  This is the name given on the
 167  * command line, or the HostName specified for the user-supplied name in a
 168  * configuration file.
 169  */
 170 char *host;
 171
 172 /* socket address the host resolves to */
 173 struct sockaddr_storage hostaddr;
 174
 175 /* Private host keys. */
 176 Sensitive sensitive_data;
 177
 178 /* Original real UID. */
 179 uid_t original_real_uid;
 180 uid_t original_effective_uid;
 181
 182 /* command to be executed */
 183 Buffer command;
 184
 185 /* Should we execute a command or invoke a subsystem? */
 186 int subsystem_flag = 0;
 187
 188 /* # of replies received for global requests */
 189 static int remote_forward_confirms_received = 0;
 190
 191 /* mux.c */
 192 extern int muxserver_sock;
 193 extern u_int muxclient_command;
 194
 195 /* Prints a help message to the user.  This function never returns. */
 196
 197 static void
 198 usage(void)
 199 {
 200         fprintf(stderr,
 201 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
 202 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 203 "           [-I pkcs11] [-i identity_file]\n"
 204 "           [-L [bind_address:]port:host:hostport]\n"
 205 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 206 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 207 "           [-W host:port] [-w local_tun[:remote_tun]]\n"
 208 "           [user@]hostname [command]\n"
 209         );
 210         exit(255);
 211 }
 212
 213 static int ssh_session(void);
 214 static int ssh_session2(void);
 215 static void load_public_identity_files(void);
 216 static void main_sigchld_handler(int);
 217
 218 /* from muxclient.c */
 219 void muxclient(const char *);
 220 void muxserver_listen(void);
 221
 222 /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
 223 static void
 224 tilde_expand_paths(char **paths, u_int num_paths)
 225 {
 226         u_int i;
 227         char *cp;
 228
 229         for (i = 0; i < num_paths; i++) {
 230                 cp = tilde_expand_filename(paths[i], original_real_uid);
 231                 xfree(paths[i]);
 232                 paths[i] = cp;
 233         }
 234 }
 235
 236 /*
 237  * Main program for the ssh client.
 238  */
 239 int
 240 main(int ac, char **av)
 241 {
 242         int i, r, opt, exit_status, use_syslog;
 243         char *p, *cp, *line, *argv0, buf[MAXPATHLEN], *host_arg;
 244         char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
 245         struct stat st;
 246         struct passwd *pw;
 247         int dummy, timeout_ms;
 248         extern int optind, optreset;
 249         extern char *optarg;
 250
 251         struct servent *sp;
 252         Forward fwd;
 253
 254         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 255         sanitise_stdfd();
 256
 257         __progname = ssh_get_progname(av[0]);
 258
 259 #ifndef HAVE_SETPROCTITLE
 260         /* Prepare for later setproctitle emulation */
 261         /* Save argv so it isn't clobbered by setproctitle() emulation */
 262         saved_av = xcalloc(ac + 1, sizeof(*saved_av));
 263         for (i = 0; i < ac; i++)
 264                 saved_av[i] = xstrdup(av[i]);
 265         saved_av[i] = NULL;
 266         compat_init_setproctitle(ac, av);
 267         av = saved_av;
 268 #endif
 269
 270         /*
 271          * Discard other fds that are hanging around. These can cause problem
 272          * with backgrounded ssh processes started by ControlPersist.
 273          */
 274         closefrom(STDERR_FILENO + 1);
 275
 276         /*
 277          * Save the original real uid.  It will be needed later (uid-swapping
 278          * may clobber the real uid).
 279          */
 280         original_real_uid = getuid();
 281         original_effective_uid = geteuid();
 282
 283         /*
 284          * Use uid-swapping to give up root privileges for the duration of
 285          * option processing.  We will re-instantiate the rights when we are
 286          * ready to create the privileged port, and will permanently drop
 287          * them when the port has been created (actually, when the connection
 288          * has been made, as we may need to create the port several times).
 289          */
 290         PRIV_END;
 291
 292 #ifdef HAVE_SETRLIMIT
 293         /* If we are installed setuid root be careful to not drop core. */
 294         if (original_real_uid != original_effective_uid) {
 295                 struct rlimit rlim;
 296                 rlim.rlim_cur = rlim.rlim_max = 0;
 297                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 298                         fatal("setrlimit failed: %.100s", strerror(errno));
 299         }
 300 #endif
 301         /* Get user data. */
 302         pw = getpwuid(original_real_uid);
 303         if (!pw) {
 304                 logit("You don't exist, go away!");
 305                 exit(255);
 306         }
 307         /* Take a copy of the returned structure. */
 308         pw = pwcopy(pw);
 309
 310         /*
 311          * Set our umask to something reasonable, as some files are created
 312          * with the default umask.  This will make them world-readable but
 313          * writable only by the owner, which is ok for all files for which we
 314          * don't set the modes explicitly.
 315          */
 316         umask(022);
 317
 318         /*
 319          * Initialize option structure to indicate that no values have been
 320          * set.
 321          */
 322         initialize_options(&options);
 323
 324         /* Parse command-line arguments. */
 325         host = NULL;
 326         use_syslog = 0;
 327         argv0 = av[0];
 328
 329  again:
 330         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 331             "ACD:F:I:KL:MNO:PR:S:TVw:W:XYy")) != -1) {
 332                 switch (opt) {
 333                 case '1':
 334                         options.protocol = SSH_PROTO_1;
 335                         break;
 336                 case '2':
 337                         options.protocol = SSH_PROTO_2;
 338                         break;
 339                 case '4':
 340                         options.address_family = AF_INET;
 341                         break;
 342                 case '6':
 343                         options.address_family = AF_INET6;
 344                         break;
 345                 case 'n':
 346                         stdin_null_flag = 1;
 347                         break;
 348                 case 'f':
 349                         fork_after_authentication_flag = 1;
 350                         stdin_null_flag = 1;
 351                         break;
 352                 case 'x':
 353                         options.forward_x11 = 0;
 354                         break;
 355                 case 'X':
 356                         options.forward_x11 = 1;
 357                         break;
 358                 case 'y':
 359                         use_syslog = 1;
 360                         break;
 361                 case 'Y':
 362                         options.forward_x11 = 1;
 363                         options.forward_x11_trusted = 1;
 364                         break;
 365                 case 'g':
 366                         options.gateway_ports = 1;
 367                         break;
 368                 case 'O':
 369                         if (stdio_forward_host != NULL)
 370                                 fatal("Cannot specify multiplexing "
 371                                     "command with -W");
 372                         else if (muxclient_command != 0)
 373                                 fatal("Multiplexing command already specified");
 374                         if (strcmp(optarg, "check") == 0)
 375                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 376                         else if (strcmp(optarg, "forward") == 0)
 377                                 muxclient_command = SSHMUX_COMMAND_FORWARD;
 378                         else if (strcmp(optarg, "exit") == 0)
 379                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 380                         else if (strcmp(optarg, "stop") == 0)
 381                                 muxclient_command = SSHMUX_COMMAND_STOP;
 382                         else
 383                                 fatal("Invalid multiplex command.");
 384                         break;
 385                 case 'P':       /* deprecated */
 386                         options.use_privileged_port = 0;
 387                         break;
 388                 case 'a':
 389                         options.forward_agent = 0;
 390                         break;
 391                 case 'A':
 392                         options.forward_agent = 1;
 393                         break;
 394                 case 'k':
 395                         options.gss_deleg_creds = 0;
 396                         break;
 397                 case 'K':
 398                         options.gss_authentication = 1;
 399                         options.gss_deleg_creds = 1;
 400                         break;
 401                 case 'i':
 402                         if (stat(optarg, &st) < 0) {
 403                                 fprintf(stderr, "Warning: Identity file %s "
 404                                     "not accessible: %s.\n", optarg,
 405                                     strerror(errno));
 406                                 break;
 407                         }
 408                         if (options.num_identity_files >=
 409                             SSH_MAX_IDENTITY_FILES)
 410                                 fatal("Too many identity files specified "
 411                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 412                         options.identity_files[options.num_identity_files++] =
 413                             xstrdup(optarg);
 414                         break;
 415                 case 'I':
 416 #ifdef ENABLE_PKCS11
 417                         options.pkcs11_provider = xstrdup(optarg);
 418 #else
 419                         fprintf(stderr, "no support for PKCS#11.\n");
 420 #endif
 421                         break;
 422                 case 't':
 423                         if (options.request_tty == REQUEST_TTY_YES)
 424                                 options.request_tty = REQUEST_TTY_FORCE;
 425                         else
 426                                 options.request_tty = REQUEST_TTY_YES;
 427                         break;
 428                 case 'v':
 429                         if (debug_flag == 0) {
 430                                 debug_flag = 1;
 431                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 432                         } else {
 433                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 434                                         options.log_level++;
 435                                 break;
 436                         }
 437                         /* FALLTHROUGH */
 438                 case 'V':
 439                         fprintf(stderr, "%s, %s\n",
 440                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 441                         if (opt == 'V')
 442                                 exit(0);
 443                         break;
 444                 case 'w':
 445                         if (options.tun_open == -1)
 446                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 447                         options.tun_local = a2tun(optarg, &options.tun_remote);
 448                         if (options.tun_local == SSH_TUNID_ERR) {
 449                                 fprintf(stderr,
 450                                     "Bad tun device '%s'\n", optarg);
 451                                 exit(255);
 452                         }
 453                         break;
 454                 case 'W':
 455                         if (stdio_forward_host != NULL)
 456                                 fatal("stdio forward already specified");
 457                         if (muxclient_command != 0)
 458                                 fatal("Cannot specify stdio forward with -O");
 459                         if (parse_forward(&fwd, optarg, 1, 0)) {
 460                                 stdio_forward_host = fwd.listen_host;
 461                                 stdio_forward_port = fwd.listen_port;
 462                                 xfree(fwd.connect_host);
 463                         } else {
 464                                 fprintf(stderr,
 465                                     "Bad stdio forwarding specification '%s'\n",
 466                                     optarg);
 467                                 exit(255);
 468                         }
 469                         options.request_tty = REQUEST_TTY_NO;
 470                         no_shell_flag = 1;
 471                         options.clear_forwardings = 1;
 472                         options.exit_on_forward_failure = 1;
 473                         break;
 474                 case 'q':
 475                         options.log_level = SYSLOG_LEVEL_QUIET;
 476                         break;
 477                 case 'e':
 478                         if (optarg[0] == '^' && optarg[2] == 0 &&
 479                             (u_char) optarg[1] >= 64 &&
 480                             (u_char) optarg[1] < 128)
 481                                 options.escape_char = (u_char) optarg[1] & 31;
 482                         else if (strlen(optarg) == 1)
 483                                 options.escape_char = (u_char) optarg[0];
 484                         else if (strcmp(optarg, "none") == 0)
 485                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 486                         else {
 487                                 fprintf(stderr, "Bad escape character '%s'.\n",
 488                                     optarg);
 489                                 exit(255);
 490                         }
 491                         break;
 492                 case 'c':
 493                         if (ciphers_valid(optarg)) {
 494                                 /* SSH2 only */
 495                                 options.ciphers = xstrdup(optarg);
 496                                 options.cipher = SSH_CIPHER_INVALID;
 497                         } else {
 498                                 /* SSH1 only */
 499                                 options.cipher = cipher_number(optarg);
 500                                 if (options.cipher == -1) {
 501                                         fprintf(stderr,
 502                                             "Unknown cipher type '%s'\n",
 503                                             optarg);
 504                                         exit(255);
 505                                 }
 506                                 if (options.cipher == SSH_CIPHER_3DES)
 507                                         options.ciphers = "3des-cbc";
 508                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 509                                         options.ciphers = "blowfish-cbc";
 510                                 else
 511                                         options.ciphers = (char *)-1;
 512                         }
 513                         break;
 514                 case 'm':
 515                         if (mac_valid(optarg))
 516                                 options.macs = xstrdup(optarg);
 517                         else {
 518                                 fprintf(stderr, "Unknown mac type '%s'\n",
 519                                     optarg);
 520                                 exit(255);
 521                         }
 522                         break;
 523                 case 'M':
 524                         if (options.control_master == SSHCTL_MASTER_YES)
 525                                 options.control_master = SSHCTL_MASTER_ASK;
 526                         else
 527                                 options.control_master = SSHCTL_MASTER_YES;
 528                         break;
 529                 case 'p':
 530                         options.port = a2port(optarg);
 531                         if (options.port <= 0) {
 532                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 533                                 exit(255);
 534                         }
 535                         break;
 536                 case 'l':
 537                         options.user = optarg;
 538                         break;
 539
 540                 case 'L':
 541                         if (parse_forward(&fwd, optarg, 0, 0))
 542                                 add_local_forward(&options, &fwd);
 543                         else {
 544                                 fprintf(stderr,
 545                                     "Bad local forwarding specification '%s'\n",
 546                                     optarg);
 547                                 exit(255);
 548                         }
 549                         break;
 550
 551                 case 'R':
 552                         if (parse_forward(&fwd, optarg, 0, 1)) {
 553                                 add_remote_forward(&options, &fwd);
 554                         } else {
 555                                 fprintf(stderr,
 556                                     "Bad remote forwarding specification "
 557                                     "'%s'\n", optarg);
 558                                 exit(255);
 559                         }
 560                         break;
 561
 562                 case 'D':
 563                         if (parse_forward(&fwd, optarg, 1, 0)) {
 564                                 add_local_forward(&options, &fwd);
 565                         } else {
 566                                 fprintf(stderr,
 567                                     "Bad dynamic forwarding specification "
 568                                     "'%s'\n", optarg);
 569                                 exit(255);
 570                         }
 571                         break;
 572
 573                 case 'C':
 574                         options.compression = 1;
 575                         break;
 576                 case 'N':
 577                         no_shell_flag = 1;
 578                         options.request_tty = REQUEST_TTY_NO;
 579                         break;
 580                 case 'T':
 581                         options.request_tty = REQUEST_TTY_NO;
 582 #ifdef  NONE_CIPHER_ENABLED
 583                         /*
 584                          * Ensure that the user does not try to backdoor a
 585                          * NONE cipher switch on an interactive session by
 586                          * explicitly disabling it if the user asks for a
 587                          * session without a tty.
 588                          */
 589                         options.none_switch = 0;
 590 #endif
 591                         break;
 592                 case 'o':
 593                         dummy = 1;
 594                         line = xstrdup(optarg);
 595                         if (process_config_line(&options, host ? host : "",
 596                             line, "command-line", 0, &dummy) != 0)
 597                                 exit(255);
 598                         xfree(line);
 599                         break;
 600                 case 's':
 601                         subsystem_flag = 1;
 602                         break;
 603                 case 'S':
 604                         if (options.control_path != NULL)
 605                                 free(options.control_path);
 606                         options.control_path = xstrdup(optarg);
 607                         break;
 608                 case 'b':
 609                         options.bind_address = optarg;
 610                         break;
 611                 case 'F':
 612                         config = optarg;
 613                         break;
 614                 default:
 615                         usage();
 616                 }
 617         }
 618
 619         ac -= optind;
 620         av += optind;
 621
 622         if (ac > 0 && !host) {
 623                 if (strrchr(*av, '@')) {
 624                         p = xstrdup(*av);
 625                         cp = strrchr(p, '@');
 626                         if (cp == NULL || cp == p)
 627                                 usage();
 628                         options.user = p;
 629                         *cp = '\0';
 630                         host = ++cp;
 631                 } else
 632                         host = *av;
 633                 if (ac > 1) {
 634                         optind = optreset = 1;
 635                         goto again;
 636                 }
 637                 ac--, av++;
 638         }
 639
 640         /* Check that we got a host name. */
 641         if (!host)
 642                 usage();
 643
 644         OpenSSL_add_all_algorithms();
 645         ERR_load_crypto_strings();
 646
 647         /* Initialize the command to execute on remote host. */
 648         buffer_init(&command);
 649
 650         if (options.request_tty == REQUEST_TTY_YES ||
 651             options.request_tty == REQUEST_TTY_FORCE)
 652                 tty_flag = 1;
 653
 654         /*
 655          * Save the command to execute on the remote host in a buffer. There
 656          * is no limit on the length of the command, except by the maximum
 657          * packet size.  Also sets the tty flag if there is no command.
 658          */
 659         if (!ac) {
 660                 /* No command specified - execute shell on a tty. */
 661                 tty_flag = options.request_tty != REQUEST_TTY_NO;
 662                 if (subsystem_flag) {
 663                         fprintf(stderr,
 664                             "You must specify a subsystem to invoke.\n");
 665                         usage();
 666                 }
 667         } else {
 668                 /* A command has been specified.  Store it into the buffer. */
 669                 for (i = 0; i < ac; i++) {
 670                         if (i)
 671                                 buffer_append(&command, " ", 1);
 672                         buffer_append(&command, av[i], strlen(av[i]));
 673                 }
 674         }
 675
 676         /* Cannot fork to background if no command. */
 677         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 678             !no_shell_flag)
 679                 fatal("Cannot fork into background without a command "
 680                     "to execute.");
 681
 682         /* Allocate a tty by default if no command specified. */
 683         if (buffer_len(&command) == 0)
 684                 tty_flag = options.request_tty != REQUEST_TTY_NO;
 685
 686         /* Force no tty */
 687         if (options.request_tty == REQUEST_TTY_NO || muxclient_command != 0)
 688                 tty_flag = 0;
 689         /* Do not allocate a tty if stdin is not a tty. */
 690         if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
 691             options.request_tty != REQUEST_TTY_FORCE) {
 692                 if (tty_flag)
 693                         logit("Pseudo-terminal will not be allocated because "
 694                             "stdin is not a terminal.");
 695                 tty_flag = 0;
 696         }
 697
 698         /*
 699          * Initialize "log" output.  Since we are the client all output
 700          * actually goes to stderr.
 701          */
 702         log_init(argv0,
 703             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 704             SYSLOG_FACILITY_USER, !use_syslog);
 705
 706         /*
 707          * Read per-user configuration file.  Ignore the system wide config
 708          * file if the user specifies a config file on the command line.
 709          */
 710         if (config != NULL) {
 711                 if (!read_config_file(config, host, &options, 0))
 712                         fatal("Can't open user config file %.100s: "
 713                             "%.100s", config, strerror(errno));
 714         } else {
 715                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 716                     _PATH_SSH_USER_CONFFILE);
 717                 if (r > 0 && (size_t)r < sizeof(buf))
 718                         (void)read_config_file(buf, host, &options, 1);
 719
 720                 /* Read systemwide configuration file after user config. */
 721                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 722                     &options, 0);
 723         }
 724
 725         /* Fill configuration defaults. */
 726         fill_default_options(&options);
 727
 728         channel_set_af(options.address_family);
 729
 730         /* reinit */
 731         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 732
 733         seed_rng();
 734
 735         if (options.user == NULL)
 736                 options.user = xstrdup(pw->pw_name);
 737
 738         /* Get default port if port has not been set. */
 739         if (options.port == 0) {
 740                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 741                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 742         }
 743
 744         /* preserve host name given on command line for %n expansion */
 745         host_arg = host;
 746         if (options.hostname != NULL) {
 747                 host = percent_expand(options.hostname,
 748                     "h", host, (char *)NULL);
 749         }
 750
 751         if (gethostname(thishost, sizeof(thishost)) == -1)
 752                 fatal("gethostname: %s", strerror(errno));
 753         strlcpy(shorthost, thishost, sizeof(shorthost));
 754         shorthost[strcspn(thishost, ".")] = '\0';
 755         snprintf(portstr, sizeof(portstr), "%d", options.port);
 756
 757         if (options.local_command != NULL) {
 758                 debug3("expanding LocalCommand: %s", options.local_command);
 759                 cp = options.local_command;
 760                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 761                     "h", host, "l", thishost, "n", host_arg, "r", options.user,
 762                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 763                     (char *)NULL);
 764                 debug3("expanded LocalCommand: %s", options.local_command);
 765                 xfree(cp);
 766         }
 767
 768         /* Find canonic host name. */
 769         if (strchr(host, '.') == 0) {
 770                 struct addrinfo hints;
 771                 struct addrinfo *ai = NULL;
 772                 int errgai;
 773                 memset(&hints, 0, sizeof(hints));
 774                 hints.ai_family = options.address_family;
 775                 hints.ai_flags = AI_CANONNAME;
 776                 hints.ai_socktype = SOCK_STREAM;
 777                 errgai = getaddrinfo(host, NULL, &hints, &ai);
 778                 if (errgai == 0) {
 779                         if (ai->ai_canonname != NULL)
 780                                 host = xstrdup(ai->ai_canonname);
 781                         freeaddrinfo(ai);
 782                 }
 783         }
 784
 785         /* force lowercase for hostkey matching */
 786         if (options.host_key_alias != NULL) {
 787                 for (p = options.host_key_alias; *p; p++)
 788                         if (isupper(*p))
 789                                 *p = (char)tolower(*p);
 790         }
 791
 792         if (options.proxy_command != NULL &&
 793             strcmp(options.proxy_command, "none") == 0) {
 794                 xfree(options.proxy_command);
 795                 options.proxy_command = NULL;
 796         }
 797         if (options.control_path != NULL &&
 798             strcmp(options.control_path, "none") == 0) {
 799                 xfree(options.control_path);
 800                 options.control_path = NULL;
 801         }
 802
 803         if (options.control_path != NULL) {
 804                 cp = tilde_expand_filename(options.control_path,
 805                     original_real_uid);
 806                 xfree(options.control_path);
 807                 options.control_path = percent_expand(cp, "h", host,
 808                     "l", thishost, "n", host_arg, "r", options.user,
 809                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 810                     (char *)NULL);
 811                 xfree(cp);
 812         }
 813         if (muxclient_command != 0 && options.control_path == NULL)
 814                 fatal("No ControlPath specified for \"-O\" command");
 815         if (options.control_path != NULL)
 816                 muxclient(options.control_path);
 817
 818         timeout_ms = options.connection_timeout * 1000;
 819
 820         /* Open a connection to the remote host. */
 821         if (ssh_connect(host, &hostaddr, options.port,
 822             options.address_family, options.connection_attempts, &timeout_ms,
 823             options.tcp_keep_alive,
 824 #ifdef HAVE_CYGWIN
 825             options.use_privileged_port,
 826 #else
 827             original_effective_uid == 0 && options.use_privileged_port,
 828 #endif
 829             options.proxy_command) != 0)
 830                 exit(255);
 831
 832         if (timeout_ms > 0)
 833                 debug3("timeout: %d ms remain after connect", timeout_ms);
 834
 835         /*
 836          * If we successfully made the connection, load the host private key
 837          * in case we will need it later for combined rsa-rhosts
 838          * authentication. This must be done before releasing extra
 839          * privileges, because the file is only readable by root.
 840          * If we cannot access the private keys, load the public keys
 841          * instead and try to execute the ssh-keysign helper instead.
 842          */
 843         sensitive_data.nkeys = 0;
 844         sensitive_data.keys = NULL;
 845         sensitive_data.external_keysign = 0;
 846         if (options.rhosts_rsa_authentication ||
 847             options.hostbased_authentication) {
 848                 sensitive_data.nkeys = 7;
 849                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 850                     sizeof(Key));
 851                 for (i = 0; i < sensitive_data.nkeys; i++)
 852                         sensitive_data.keys[i] = NULL;
 853
 854                 PRIV_START;
 855                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 856                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 857                 sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
 858                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 859 #ifdef OPENSSL_HAS_ECC
 860                 sensitive_data.keys[2] = key_load_private_cert(KEY_ECDSA,
 861                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
 862 #endif
 863                 sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
 864                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 865                 sensitive_data.keys[4] = key_load_private_type(KEY_DSA,
 866                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 867 #ifdef OPENSSL_HAS_ECC
 868                 sensitive_data.keys[5] = key_load_private_type(KEY_ECDSA,
 869                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
 870 #endif
 871                 sensitive_data.keys[6] = key_load_private_type(KEY_RSA,
 872                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 873                 PRIV_END;
 874
 875                 if (options.hostbased_authentication == 1 &&
 876                     sensitive_data.keys[0] == NULL &&
 877                     sensitive_data.keys[4] == NULL &&
 878                     sensitive_data.keys[5] == NULL &&
 879                     sensitive_data.keys[6] == NULL) {
 880                         sensitive_data.keys[1] = key_load_cert(
 881                             _PATH_HOST_DSA_KEY_FILE);
 882 #ifdef OPENSSL_HAS_ECC
 883                         sensitive_data.keys[2] = key_load_cert(
 884                             _PATH_HOST_ECDSA_KEY_FILE);
 885 #endif
 886                         sensitive_data.keys[3] = key_load_cert(
 887                             _PATH_HOST_RSA_KEY_FILE);
 888                         sensitive_data.keys[4] = key_load_public(
 889                             _PATH_HOST_DSA_KEY_FILE, NULL);
 890 #ifdef OPENSSL_HAS_ECC
 891                         sensitive_data.keys[5] = key_load_public(
 892                             _PATH_HOST_ECDSA_KEY_FILE, NULL);
 893 #endif
 894                         sensitive_data.keys[6] = key_load_public(
 895                             _PATH_HOST_RSA_KEY_FILE, NULL);
 896                         sensitive_data.external_keysign = 1;
 897                 }
 898         }
 899         /*
 900          * Get rid of any extra privileges that we may have.  We will no
 901          * longer need them.  Also, extra privileges could make it very hard
 902          * to read identity files and other non-world-readable files from the
 903          * user's home directory if it happens to be on a NFS volume where
 904          * root is mapped to nobody.
 905          */
 906         if (original_effective_uid == 0) {
 907                 PRIV_START;
 908                 permanently_set_uid(pw);
 909         }
 910
 911         /*
 912          * Now that we are back to our own permissions, create ~/.ssh
 913          * directory if it doesn't already exist.
 914          */
 915         r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
 916             strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 917         if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
 918 #ifdef WITH_SELINUX
 919                 ssh_selinux_setfscreatecon(buf);
 920 #endif
 921                 if (mkdir(buf, 0700) < 0)
 922                         error("Could not create directory '%.200s'.", buf);
 923 #ifdef WITH_SELINUX
 924                 ssh_selinux_setfscreatecon(NULL);
 925 #endif
 926         }
 927         /* load options.identity_files */
 928         load_public_identity_files();
 929
 930         /* Expand ~ in known host file names. */
 931         tilde_expand_paths(options.system_hostfiles,
 932             options.num_system_hostfiles);
 933         tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
 934
 935         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 936         signal(SIGCHLD, main_sigchld_handler);
 937
 938         /* Log into the remote system.  Never returns if the login fails. */
 939         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 940             options.port, pw, timeout_ms);
 941
 942         if (packet_connection_is_on_socket()) {
 943                 verbose("Authenticated to %s ([%s]:%d).", host,
 944                     get_remote_ipaddr(), get_remote_port());
 945         } else {
 946                 verbose("Authenticated to %s (via proxy).", host);
 947         }
 948
 949         /* We no longer need the private host keys.  Clear them now. */
 950         if (sensitive_data.nkeys != 0) {
 951                 for (i = 0; i < sensitive_data.nkeys; i++) {
 952                         if (sensitive_data.keys[i] != NULL) {
 953                                 /* Destroys contents safely */
 954                                 debug3("clear hostkey %d", i);
 955                                 key_free(sensitive_data.keys[i]);
 956                                 sensitive_data.keys[i] = NULL;
 957                         }
 958                 }
 959                 xfree(sensitive_data.keys);
 960         }
 961         for (i = 0; i < options.num_identity_files; i++) {
 962                 if (options.identity_files[i]) {
 963                         xfree(options.identity_files[i]);
 964                         options.identity_files[i] = NULL;
 965                 }
 966                 if (options.identity_keys[i]) {
 967                         key_free(options.identity_keys[i]);
 968                         options.identity_keys[i] = NULL;
 969                 }
 970         }
 971
 972         exit_status = compat20 ? ssh_session2() : ssh_session();
 973         packet_close();
 974
 975         if (options.control_path != NULL && muxserver_sock != -1)
 976                 unlink(options.control_path);
 977
 978         /* Kill ProxyCommand if it is running. */
 979         ssh_kill_proxy_command();
 980
 981         return exit_status;
 982 }
 983
 984 static void
 985 control_persist_detach(void)
 986 {
 987         pid_t pid;
 988         int devnull;
 989
 990         debug("%s: backgrounding master process", __func__);
 991
 992         /*
 993          * master (current process) into the background, and make the
 994          * foreground process a client of the backgrounded master.
 995          */
 996         switch ((pid = fork())) {
 997         case -1:
 998                 fatal("%s: fork: %s", __func__, strerror(errno));
 999         case 0:
1000                 /* Child: master process continues mainloop */
1001                 break;
1002         default:
1003                 /* Parent: set up mux slave to connect to backgrounded master */
1004                 debug2("%s: background process is %ld", __func__, (long)pid);
1005                 stdin_null_flag = ostdin_null_flag;
1006                 options.request_tty = orequest_tty;
1007                 tty_flag = otty_flag;
1008                 close(muxserver_sock);
1009                 muxserver_sock = -1;
1010                 options.control_master = SSHCTL_MASTER_NO;
1011                 muxclient(options.control_path);
1012                 /* muxclient() doesn't return on success. */
1013                 fatal("Failed to connect to new control master");
1014         }
1015         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1016                 error("%s: open(\"/dev/null\"): %s", __func__,
1017                     strerror(errno));
1018         } else {
1019                 if (dup2(devnull, STDIN_FILENO) == -1 ||
1020                     dup2(devnull, STDOUT_FILENO) == -1)
1021                         error("%s: dup2: %s", __func__, strerror(errno));
1022                 if (devnull > STDERR_FILENO)
1023                         close(devnull);
1024         }
1025         setproctitle("%s [mux]", options.control_path);
1026 }
1027
1028 /* Do fork() after authentication. Used by "ssh -f" */
1029 static void
1030 fork_postauth(void)
1031 {
1032         if (need_controlpersist_detach)
1033                 control_persist_detach();
1034         debug("forking to background");
1035         fork_after_authentication_flag = 0;
1036         if (daemon(1, 1) < 0)
1037                 fatal("daemon() failed: %.200s", strerror(errno));
1038 }
1039
1040 /* Callback for remote forward global requests */
1041 static void
1042 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
1043 {
1044         Forward *rfwd = (Forward *)ctxt;
1045
1046         /* XXX verbose() on failure? */
1047         debug("remote forward %s for: listen %d, connect %s:%d",
1048             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1049             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
1050         if (type == SSH2_MSG_REQUEST_SUCCESS && rfwd->listen_port == 0) {
1051                 rfwd->allocated_port = packet_get_int();
1052                 logit("Allocated port %u for remote forward to %s:%d",
1053                     rfwd->allocated_port,
1054                     rfwd->connect_host, rfwd->connect_port);
1055         }
1056
1057         if (type == SSH2_MSG_REQUEST_FAILURE) {
1058                 if (options.exit_on_forward_failure)
1059                         fatal("Error: remote port forwarding failed for "
1060                             "listen port %d", rfwd->listen_port);
1061                 else
1062                         logit("Warning: remote port forwarding failed for "
1063                             "listen port %d", rfwd->listen_port);
1064         }
1065         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1066                 debug("All remote forwarding requests processed");
1067                 if (fork_after_authentication_flag)
1068                         fork_postauth();
1069         }
1070 }
1071
1072 static void
1073 client_cleanup_stdio_fwd(int id, void *arg)
1074 {
1075         debug("stdio forwarding: done");
1076         cleanup_exit(0);
1077 }
1078
1079 static int
1080 client_setup_stdio_fwd(const char *host_to_connect, u_short port_to_connect)
1081 {
1082         Channel *c;
1083         int in, out;
1084
1085         debug3("client_setup_stdio_fwd %s:%d", host_to_connect,
1086             port_to_connect);
1087
1088         in = dup(STDIN_FILENO);
1089         out = dup(STDOUT_FILENO);
1090         if (in < 0 || out < 0)
1091                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1092
1093         if ((c = channel_connect_stdio_fwd(host_to_connect, port_to_connect,
1094             in, out)) == NULL)
1095                 return 0;
1096         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1097         return 1;
1098 }
1099
1100 static void
1101 ssh_init_forwarding(void)
1102 {
1103         int success = 0;
1104         int i;
1105
1106         if (stdio_forward_host != NULL) {
1107                 if (!compat20) {
1108                         fatal("stdio forwarding require Protocol 2");
1109                 }
1110                 if (!client_setup_stdio_fwd(stdio_forward_host,
1111                     stdio_forward_port))
1112                         fatal("Failed to connect in stdio forward mode.");
1113         }
1114
1115         /* Initiate local TCP/IP port forwardings. */
1116         for (i = 0; i < options.num_local_forwards; i++) {
1117                 debug("Local connections to %.200s:%d forwarded to remote "
1118                     "address %.200s:%d",
1119                     (options.local_forwards[i].listen_host == NULL) ?
1120                     (options.gateway_ports ? "*" : "LOCALHOST") :
1121                     options.local_forwards[i].listen_host,
1122                     options.local_forwards[i].listen_port,
1123                     options.local_forwards[i].connect_host,
1124                     options.local_forwards[i].connect_port);
1125                 success += channel_setup_local_fwd_listener(
1126                     options.local_forwards[i].listen_host,
1127                     options.local_forwards[i].listen_port,
1128                     options.local_forwards[i].connect_host,
1129                     options.local_forwards[i].connect_port,
1130                     options.gateway_ports);
1131         }
1132         if (i > 0 && success != i && options.exit_on_forward_failure)
1133                 fatal("Could not request local forwarding.");
1134         if (i > 0 && success == 0)
1135                 error("Could not request local forwarding.");
1136
1137         /* Initiate remote TCP/IP port forwardings. */
1138         for (i = 0; i < options.num_remote_forwards; i++) {
1139                 debug("Remote connections from %.200s:%d forwarded to "
1140                     "local address %.200s:%d",
1141                     (options.remote_forwards[i].listen_host == NULL) ?
1142                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1143                     options.remote_forwards[i].listen_port,
1144                     options.remote_forwards[i].connect_host,
1145                     options.remote_forwards[i].connect_port);
1146                 if (channel_request_remote_forwarding(
1147                     options.remote_forwards[i].listen_host,
1148                     options.remote_forwards[i].listen_port,
1149                     options.remote_forwards[i].connect_host,
1150                     options.remote_forwards[i].connect_port) < 0) {
1151                         if (options.exit_on_forward_failure)
1152                                 fatal("Could not request remote forwarding.");
1153                         else
1154                                 logit("Warning: Could not request remote "
1155                                     "forwarding.");
1156                 }
1157                 client_register_global_confirm(ssh_confirm_remote_forward,
1158                     &options.remote_forwards[i]);
1159         }
1160
1161         /* Initiate tunnel forwarding. */
1162         if (options.tun_open != SSH_TUNMODE_NO) {
1163                 if (client_request_tun_fwd(options.tun_open,
1164                     options.tun_local, options.tun_remote) == -1) {
1165                         if (options.exit_on_forward_failure)
1166                                 fatal("Could not request tunnel forwarding.");
1167                         else
1168                                 error("Could not request tunnel forwarding.");
1169                 }
1170         }
1171 }
1172
1173 static void
1174 check_agent_present(void)
1175 {
1176         if (options.forward_agent) {
1177                 /* Clear agent forwarding if we don't have an agent. */
1178                 if (!ssh_agent_present())
1179                         options.forward_agent = 0;
1180         }
1181 }
1182
1183 static int
1184 ssh_session(void)
1185 {
1186         int type;
1187         int interactive = 0;
1188         int have_tty = 0;
1189         struct winsize ws;
1190         char *cp;
1191         const char *display;
1192
1193         /* Enable compression if requested. */
1194         if (options.compression) {
1195                 debug("Requesting compression at level %d.",
1196                     options.compression_level);
1197
1198                 if (options.compression_level < 1 ||
1199                     options.compression_level > 9)
1200                         fatal("Compression level must be from 1 (fast) to "
1201                             "9 (slow, best).");
1202
1203                 /* Send the request. */
1204                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1205                 packet_put_int(options.compression_level);
1206                 packet_send();
1207                 packet_write_wait();
1208                 type = packet_read();
1209                 if (type == SSH_SMSG_SUCCESS)
1210                         packet_start_compression(options.compression_level);
1211                 else if (type == SSH_SMSG_FAILURE)
1212                         logit("Warning: Remote host refused compression.");
1213                 else
1214                         packet_disconnect("Protocol error waiting for "
1215                             "compression response.");
1216         }
1217         /* Allocate a pseudo tty if appropriate. */
1218         if (tty_flag) {
1219                 debug("Requesting pty.");
1220
1221                 /* Start the packet. */
1222                 packet_start(SSH_CMSG_REQUEST_PTY);
1223
1224                 /* Store TERM in the packet.  There is no limit on the
1225                    length of the string. */
1226                 cp = getenv("TERM");
1227                 if (!cp)
1228                         cp = "";
1229                 packet_put_cstring(cp);
1230
1231                 /* Store window size in the packet. */
1232                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1233                         memset(&ws, 0, sizeof(ws));
1234                 packet_put_int((u_int)ws.ws_row);
1235                 packet_put_int((u_int)ws.ws_col);
1236                 packet_put_int((u_int)ws.ws_xpixel);
1237                 packet_put_int((u_int)ws.ws_ypixel);
1238
1239                 /* Store tty modes in the packet. */
1240                 tty_make_modes(fileno(stdin), NULL);
1241
1242                 /* Send the packet, and wait for it to leave. */
1243                 packet_send();
1244                 packet_write_wait();
1245
1246                 /* Read response from the server. */
1247                 type = packet_read();
1248                 if (type == SSH_SMSG_SUCCESS) {
1249                         interactive = 1;
1250                         have_tty = 1;
1251                 } else if (type == SSH_SMSG_FAILURE)
1252                         logit("Warning: Remote host failed or refused to "
1253                             "allocate a pseudo tty.");
1254                 else
1255                         packet_disconnect("Protocol error waiting for pty "
1256                             "request response.");
1257         }
1258         /* Request X11 forwarding if enabled and DISPLAY is set. */
1259         display = getenv("DISPLAY");
1260         if (options.forward_x11 && display != NULL) {
1261                 char *proto, *data;
1262                 /* Get reasonable local authentication information. */
1263                 client_x11_get_proto(display, options.xauth_location,
1264                     options.forward_x11_trusted,
1265                     options.forward_x11_timeout,
1266                     &proto, &data);
1267                 /* Request forwarding with authentication spoofing. */
1268                 debug("Requesting X11 forwarding with authentication "
1269                     "spoofing.");
1270                 x11_request_forwarding_with_spoofing(0, display, proto,
1271                     data, 0);
1272                 /* Read response from the server. */
1273                 type = packet_read();
1274                 if (type == SSH_SMSG_SUCCESS) {
1275                         interactive = 1;
1276                 } else if (type == SSH_SMSG_FAILURE) {
1277                         logit("Warning: Remote host denied X11 forwarding.");
1278                 } else {
1279                         packet_disconnect("Protocol error waiting for X11 "
1280                             "forwarding");
1281                 }
1282         }
1283         /* Tell the packet module whether this is an interactive session. */
1284         packet_set_interactive(interactive,
1285             options.ip_qos_interactive, options.ip_qos_bulk);
1286
1287         /* Request authentication agent forwarding if appropriate. */
1288         check_agent_present();
1289
1290         if (options.forward_agent) {
1291                 debug("Requesting authentication agent forwarding.");
1292                 auth_request_forwarding();
1293
1294                 /* Read response from the server. */
1295                 type = packet_read();
1296                 packet_check_eom();
1297                 if (type != SSH_SMSG_SUCCESS)
1298                         logit("Warning: Remote host denied authentication agent forwarding.");
1299         }
1300
1301         /* Initiate port forwardings. */
1302         ssh_init_forwarding();
1303
1304         /* Execute a local command */
1305         if (options.local_command != NULL &&
1306             options.permit_local_command)
1307                 ssh_local_cmd(options.local_command);
1308
1309         /*
1310          * If requested and we are not interested in replies to remote
1311          * forwarding requests, then let ssh continue in the background.
1312          */
1313         if (fork_after_authentication_flag) {
1314                 if (options.exit_on_forward_failure &&
1315                     options.num_remote_forwards > 0) {
1316                         debug("deferring postauth fork until remote forward "
1317                             "confirmation received");
1318                 } else
1319                         fork_postauth();
1320         }
1321
1322         /*
1323          * If a command was specified on the command line, execute the
1324          * command now. Otherwise request the server to start a shell.
1325          */
1326         if (buffer_len(&command) > 0) {
1327                 int len = buffer_len(&command);
1328                 if (len > 900)
1329                         len = 900;
1330                 debug("Sending command: %.*s", len,
1331                     (u_char *)buffer_ptr(&command));
1332                 packet_start(SSH_CMSG_EXEC_CMD);
1333                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1334                 packet_send();
1335                 packet_write_wait();
1336         } else {
1337                 debug("Requesting shell.");
1338                 packet_start(SSH_CMSG_EXEC_SHELL);
1339                 packet_send();
1340                 packet_write_wait();
1341         }
1342
1343         /* Enter the interactive session. */
1344         return client_loop(have_tty, tty_flag ?
1345             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1346 }
1347
1348 /* request pty/x11/agent/tcpfwd/shell for channel */
1349 static void
1350 ssh_session2_setup(int id, int success, void *arg)
1351 {
1352         extern char **environ;
1353         const char *display;
1354         int interactive = tty_flag;
1355
1356         if (!success)
1357                 return; /* No need for error message, channels code sens one */
1358
1359         display = getenv("DISPLAY");
1360         if (options.forward_x11 && display != NULL) {
1361                 char *proto, *data;
1362                 /* Get reasonable local authentication information. */
1363                 client_x11_get_proto(display, options.xauth_location,
1364                     options.forward_x11_trusted,
1365                     options.forward_x11_timeout, &proto, &data);
1366                 /* Request forwarding with authentication spoofing. */
1367                 debug("Requesting X11 forwarding with authentication "
1368                     "spoofing.");
1369                 x11_request_forwarding_with_spoofing(id, display, proto,
1370                     data, 1);
1371                 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
1372                 /* XXX exit_on_forward_failure */
1373                 interactive = 1;
1374         }
1375
1376         check_agent_present();
1377         if (options.forward_agent) {
1378                 debug("Requesting authentication agent forwarding.");
1379                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1380                 packet_send();
1381         }
1382
1383         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1384             NULL, fileno(stdin), &command, environ);
1385 }
1386
1387 /* open new channel for a session */
1388 static int
1389 ssh_session2_open(void)
1390 {
1391         Channel *c;
1392         int window, packetmax, in, out, err;
1393
1394         if (stdin_null_flag) {
1395                 in = open(_PATH_DEVNULL, O_RDONLY);
1396         } else {
1397                 in = dup(STDIN_FILENO);
1398         }
1399         out = dup(STDOUT_FILENO);
1400         err = dup(STDERR_FILENO);
1401
1402         if (in < 0 || out < 0 || err < 0)
1403                 fatal("dup() in/out/err failed");
1404
1405         /* enable nonblocking unless tty */
1406         if (!isatty(in))
1407                 set_nonblock(in);
1408         if (!isatty(out))
1409                 set_nonblock(out);
1410         if (!isatty(err))
1411                 set_nonblock(err);
1412
1413         /*
1414          * We need to check to see what to do about buffer sizes here.
1415          * - In an HPN to non-HPN connection we want to limit the window size to
1416          *   something reasonable in case the far side has the large window bug.
1417          * - In an HPN to HPN connection we want to use the max window size but
1418          *   allow the user to override it.
1419          * - Lastly if HPN is disabled then use the ssh standard window size.
1420          *
1421          * We cannot just do a getsockopt() here and set the ssh window to that
1422          * as in case of autotuning of socket buffers the window would get stuck
1423          * at the initial buffer size, generally less than 96k.  Therefore we
1424          * need to set the maximum ssh window size to the maximum HPN buffer
1425          * size unless the user has set TcpRcvBufPoll to no.  In that case we
1426          * can just set the window to the minimum of HPN buffer size and TCP
1427          * receive buffer size.
1428          */
1429         if (tty_flag)
1430                 options.hpn_buffer_size = CHAN_SES_WINDOW_DEFAULT;
1431         else
1432                 options.hpn_buffer_size = CHAN_HPN_MIN_WINDOW_DEFAULT;
1433
1434         if (datafellows & SSH_BUG_LARGEWINDOW) {
1435                 debug("HPN to Non-HPN Connection");
1436         } else if (options.tcp_rcv_buf_poll <= 0) {
1437                 sock_get_rcvbuf(&options.hpn_buffer_size, 0);
1438                 debug("HPNBufferSize set to TCP RWIN: %d",
1439                     options.hpn_buffer_size);
1440         } else if (options.tcp_rcv_buf > 0) {
1441                 sock_get_rcvbuf(&options.hpn_buffer_size,
1442                     options.tcp_rcv_buf);
1443                 debug("HPNBufferSize set to user TCPRcvBuf: %d",
1444                     options.hpn_buffer_size);
1445         }
1446         debug("Final hpn_buffer_size = %d", options.hpn_buffer_size);
1447         channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1448         window = options.hpn_buffer_size;
1449
1450         packetmax = CHAN_SES_PACKET_DEFAULT;
1451         if (tty_flag) {
1452                 window = CHAN_SES_WINDOW_DEFAULT;
1453                 window >>= 1;
1454                 packetmax >>= 1;
1455         }
1456         c = channel_new(
1457             "session", SSH_CHANNEL_OPENING, in, out, err,
1458             window, packetmax, CHAN_EXTENDED_WRITE,
1459             "client-session", /*nonblock*/0);
1460         if (!options.hpn_disabled && options.tcp_rcv_buf_poll > 0) {
1461                 c->dynamic_window = 1;
1462                 debug("Enabled Dynamic Window Scaling\n");
1463         }
1464         debug3("ssh_session2_open: channel_new: %d", c->self);
1465
1466         channel_send_open(c->self);
1467         if (!no_shell_flag)
1468                 channel_register_open_confirm(c->self,
1469                     ssh_session2_setup, NULL);
1470
1471         return c->self;
1472 }
1473
1474 static int
1475 ssh_session2(void)
1476 {
1477         int id = -1;
1478
1479         /* XXX should be pre-session */
1480         ssh_init_forwarding();
1481
1482         /* Start listening for multiplex clients */
1483         muxserver_listen();
1484
1485         /*
1486          * If we are in control persist mode, then prepare to background
1487          * ourselves and have a foreground client attach as a control
1488          * slave. NB. we must save copies of the flags that we override for
1489          * the backgrounding, since we defer attachment of the slave until
1490          * after the connection is fully established (in particular,
1491          * async rfwd replies have been received for ExitOnForwardFailure).
1492          */
1493         if (options.control_persist && muxserver_sock != -1) {
1494                 ostdin_null_flag = stdin_null_flag;
1495                 ono_shell_flag = no_shell_flag;
1496                 orequest_tty = options.request_tty;
1497                 otty_flag = tty_flag;
1498                 stdin_null_flag = 1;
1499                 no_shell_flag = 1;
1500                 tty_flag = 0;
1501                 if (!fork_after_authentication_flag)
1502                         need_controlpersist_detach = 1;
1503                 fork_after_authentication_flag = 1;
1504         }
1505
1506         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1507                 id = ssh_session2_open();
1508
1509         /* If we don't expect to open a new session, then disallow it */
1510         if (options.control_master == SSHCTL_MASTER_NO &&
1511             (datafellows & SSH_NEW_OPENSSH)) {
1512                 debug("Requesting no-more-sessions@openssh.com");
1513                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1514                 packet_put_cstring("no-more-sessions@openssh.com");
1515                 packet_put_char(0);
1516                 packet_send();
1517         }
1518
1519         /* Execute a local command */
1520         if (options.local_command != NULL &&
1521             options.permit_local_command)
1522                 ssh_local_cmd(options.local_command);
1523
1524         /*
1525          * If requested and we are not interested in replies to remote
1526          * forwarding requests, then let ssh continue in the background.
1527          */
1528         if (fork_after_authentication_flag) {
1529                 if (options.exit_on_forward_failure &&
1530                     options.num_remote_forwards > 0) {
1531                         debug("deferring postauth fork until remote forward "
1532                             "confirmation received");
1533                 } else
1534                         fork_postauth();
1535         }
1536
1537         if (options.use_roaming)
1538                 request_roaming();
1539
1540         return client_loop(tty_flag, tty_flag ?
1541             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1542 }
1543
1544 static void
1545 load_public_identity_files(void)
1546 {
1547         char *filename, *cp, thishost[NI_MAXHOST];
1548         char *pwdir = NULL, *pwname = NULL;
1549         int i = 0;
1550         Key *public;
1551         struct passwd *pw;
1552         u_int n_ids;
1553         char *identity_files[SSH_MAX_IDENTITY_FILES];
1554         Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1555 #ifdef ENABLE_PKCS11
1556         Key **keys;
1557         int nkeys;
1558 #endif /* PKCS11 */
1559
1560         n_ids = 0;
1561         bzero(identity_files, sizeof(identity_files));
1562         bzero(identity_keys, sizeof(identity_keys));
1563
1564 #ifdef ENABLE_PKCS11
1565         if (options.pkcs11_provider != NULL &&
1566             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1567             (pkcs11_init(!options.batch_mode) == 0) &&
1568             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1569             &keys)) > 0) {
1570                 for (i = 0; i < nkeys; i++) {
1571                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1572                                 key_free(keys[i]);
1573                                 continue;
1574                         }
1575                         identity_keys[n_ids] = keys[i];
1576                         identity_files[n_ids] =
1577                             xstrdup(options.pkcs11_provider); /* XXX */
1578                         n_ids++;
1579                 }
1580                 xfree(keys);
1581         }
1582 #endif /* ENABLE_PKCS11 */
1583         if ((pw = getpwuid(original_real_uid)) == NULL)
1584                 fatal("load_public_identity_files: getpwuid failed");
1585         pwname = xstrdup(pw->pw_name);
1586         pwdir = xstrdup(pw->pw_dir);
1587         if (gethostname(thishost, sizeof(thishost)) == -1)
1588                 fatal("load_public_identity_files: gethostname: %s",
1589                     strerror(errno));
1590         for (i = 0; i < options.num_identity_files; i++) {
1591                 if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1592                         xfree(options.identity_files[i]);
1593                         continue;
1594                 }
1595                 cp = tilde_expand_filename(options.identity_files[i],
1596                     original_real_uid);
1597                 filename = percent_expand(cp, "d", pwdir,
1598                     "u", pwname, "l", thishost, "h", host,
1599                     "r", options.user, (char *)NULL);
1600                 xfree(cp);
1601                 public = key_load_public(filename, NULL);
1602                 debug("identity file %s type %d", filename,
1603                     public ? public->type : -1);
1604                 xfree(options.identity_files[i]);
1605                 identity_files[n_ids] = filename;
1606                 identity_keys[n_ids] = public;
1607
1608                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
1609                         continue;
1610
1611                 /* Try to add the certificate variant too */
1612                 xasprintf(&cp, "%s-cert", filename);
1613                 public = key_load_public(cp, NULL);
1614                 debug("identity file %s type %d", cp,
1615                     public ? public->type : -1);
1616                 if (public == NULL) {
1617                         xfree(cp);
1618                         continue;
1619                 }
1620                 if (!key_is_cert(public)) {
1621                         debug("%s: key %s type %s is not a certificate",
1622                             __func__, cp, key_type(public));
1623                         key_free(public);
1624                         xfree(cp);
1625                         continue;
1626                 }
1627                 identity_keys[n_ids] = public;
1628                 /* point to the original path, most likely the private key */
1629                 identity_files[n_ids] = xstrdup(filename);
1630                 n_ids++;
1631         }
1632         options.num_identity_files = n_ids;
1633         memcpy(options.identity_files, identity_files, sizeof(identity_files));
1634         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
1635
1636         bzero(pwname, strlen(pwname));
1637         xfree(pwname);
1638         bzero(pwdir, strlen(pwdir));
1639         xfree(pwdir);
1640 }
1641
1642 static void
1643 main_sigchld_handler(int sig)
1644 {
1645         int save_errno = errno;
1646         pid_t pid;
1647         int status;
1648
1649         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
1650             (pid < 0 && errno == EINTR))
1651                 ;
1652
1653         signal(sig, main_sigchld_handler);
1654         errno = save_errno;
1655 }
1656