crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.370 2012/07/06 01:47:38 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 /* Saves a copy of argv for setproctitle emulation */
 115 #ifndef HAVE_SETPROCTITLE
 116 static char **saved_av;
 117 #endif
 118
 119 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 120 int debug_flag = 0;
 121
 122 /* Flag indicating whether a tty should be requested */
 123 int tty_flag = 0;
 124
 125 /* don't exec a shell */
 126 int no_shell_flag = 0;
 127
 128 /*
 129  * Flag indicating that nothing should be read from stdin.  This can be set
 130  * on the command line.
 131  */
 132 int stdin_null_flag = 0;
 133
 134 /*
 135  * Flag indicating that the current process should be backgrounded and
 136  * a new slave launched in the foreground for ControlPersist.
 137  */
 138 int need_controlpersist_detach = 0;
 139
 140 /* Copies of flags for ControlPersist foreground slave */
 141 int ostdin_null_flag, ono_shell_flag, otty_flag, orequest_tty;
 142
 143 /*
 144  * Flag indicating that ssh should fork after authentication.  This is useful
 145  * so that the passphrase can be entered manually, and then ssh goes to the
 146  * background.
 147  */
 148 int fork_after_authentication_flag = 0;
 149
 150 /* forward stdio to remote host and port */
 151 char *stdio_forward_host = NULL;
 152 int stdio_forward_port = 0;
 153
 154 /*
 155  * General data structure for command line options and options configurable
 156  * in configuration files.  See readconf.h.
 157  */
 158 Options options;
 159
 160 /* optional user configfile */
 161 char *config = NULL;
 162
 163 /*
 164  * Name of the host we are connecting to.  This is the name given on the
 165  * command line, or the HostName specified for the user-supplied name in a
 166  * configuration file.
 167  */
 168 char *host;
 169
 170 /* socket address the host resolves to */
 171 struct sockaddr_storage hostaddr;
 172
 173 /* Private host keys. */
 174 Sensitive sensitive_data;
 175
 176 /* Original real UID. */
 177 uid_t original_real_uid;
 178 uid_t original_effective_uid;
 179
 180 /* command to be executed */
 181 Buffer command;
 182
 183 /* Should we execute a command or invoke a subsystem? */
 184 int subsystem_flag = 0;
 185
 186 /* # of replies received for global requests */
 187 static int remote_forward_confirms_received = 0;
 188
 189 /* mux.c */
 190 extern int muxserver_sock;
 191 extern u_int muxclient_command;
 192
 193 /* Prints a help message to the user.  This function never returns. */
 194
 195 static void
 196 usage(void)
 197 {
 198         fprintf(stderr,
 199 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
 200 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 201 "           [-I pkcs11] [-i identity_file]\n"
 202 "           [-L [bind_address:]port:host:hostport]\n"
 203 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 204 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 205 "           [-W host:port] [-w local_tun[:remote_tun]]\n"
 206 "           [user@]hostname [command]\n"
 207         );
 208         exit(255);
 209 }
 210
 211 static int ssh_session(void);
 212 static int ssh_session2(void);
 213 static void load_public_identity_files(void);
 214 static void main_sigchld_handler(int);
 215
 216 /* from muxclient.c */
 217 void muxclient(const char *);
 218 void muxserver_listen(void);
 219
 220 /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
 221 static void
 222 tilde_expand_paths(char **paths, u_int num_paths)
 223 {
 224         u_int i;
 225         char *cp;
 226
 227         for (i = 0; i < num_paths; i++) {
 228                 cp = tilde_expand_filename(paths[i], original_real_uid);
 229                 xfree(paths[i]);
 230                 paths[i] = cp;
 231         }
 232 }
 233
 234 /*
 235  * Main program for the ssh client.
 236  */
 237 int
 238 main(int ac, char **av)
 239 {
 240         int i, r, opt, exit_status, use_syslog;
 241         char *p, *cp, *line, *argv0, buf[MAXPATHLEN], *host_arg;
 242         char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
 243         struct stat st;
 244         struct passwd *pw;
 245         int dummy, timeout_ms;
 246         extern int optind, optreset;
 247         extern char *optarg;
 248
 249         struct servent *sp;
 250         Forward fwd;
 251
 252         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 253         sanitise_stdfd();
 254
 255         __progname = ssh_get_progname(av[0]);
 256
 257 #ifndef HAVE_SETPROCTITLE
 258         /* Prepare for later setproctitle emulation */
 259         /* Save argv so it isn't clobbered by setproctitle() emulation */
 260         saved_av = xcalloc(ac + 1, sizeof(*saved_av));
 261         for (i = 0; i < ac; i++)
 262                 saved_av[i] = xstrdup(av[i]);
 263         saved_av[i] = NULL;
 264         compat_init_setproctitle(ac, av);
 265         av = saved_av;
 266 #endif
 267
 268         /*
 269          * Discard other fds that are hanging around. These can cause problem
 270          * with backgrounded ssh processes started by ControlPersist.
 271          */
 272         closefrom(STDERR_FILENO + 1);
 273
 274         /*
 275          * Save the original real uid.  It will be needed later (uid-swapping
 276          * may clobber the real uid).
 277          */
 278         original_real_uid = getuid();
 279         original_effective_uid = geteuid();
 280
 281         /*
 282          * Use uid-swapping to give up root privileges for the duration of
 283          * option processing.  We will re-instantiate the rights when we are
 284          * ready to create the privileged port, and will permanently drop
 285          * them when the port has been created (actually, when the connection
 286          * has been made, as we may need to create the port several times).
 287          */
 288         PRIV_END;
 289
 290 #ifdef HAVE_SETRLIMIT
 291         /* If we are installed setuid root be careful to not drop core. */
 292         if (original_real_uid != original_effective_uid) {
 293                 struct rlimit rlim;
 294                 rlim.rlim_cur = rlim.rlim_max = 0;
 295                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 296                         fatal("setrlimit failed: %.100s", strerror(errno));
 297         }
 298 #endif
 299         /* Get user data. */
 300         pw = getpwuid(original_real_uid);
 301         if (!pw) {
 302                 logit("You don't exist, go away!");
 303                 exit(255);
 304         }
 305         /* Take a copy of the returned structure. */
 306         pw = pwcopy(pw);
 307
 308         /*
 309          * Set our umask to something reasonable, as some files are created
 310          * with the default umask.  This will make them world-readable but
 311          * writable only by the owner, which is ok for all files for which we
 312          * don't set the modes explicitly.
 313          */
 314         umask(022);
 315
 316         /*
 317          * Initialize option structure to indicate that no values have been
 318          * set.
 319          */
 320         initialize_options(&options);
 321
 322         /* Parse command-line arguments. */
 323         host = NULL;
 324         use_syslog = 0;
 325         argv0 = av[0];
 326
 327  again:
 328         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 329             "ACD:F:I:KL:MNO:PR:S:TVw:W:XYy")) != -1) {
 330                 switch (opt) {
 331                 case '1':
 332                         options.protocol = SSH_PROTO_1;
 333                         break;
 334                 case '2':
 335                         options.protocol = SSH_PROTO_2;
 336                         break;
 337                 case '4':
 338                         options.address_family = AF_INET;
 339                         break;
 340                 case '6':
 341                         options.address_family = AF_INET6;
 342                         break;
 343                 case 'n':
 344                         stdin_null_flag = 1;
 345                         break;
 346                 case 'f':
 347                         fork_after_authentication_flag = 1;
 348                         stdin_null_flag = 1;
 349                         break;
 350                 case 'x':
 351                         options.forward_x11 = 0;
 352                         break;
 353                 case 'X':
 354                         options.forward_x11 = 1;
 355                         break;
 356                 case 'y':
 357                         use_syslog = 1;
 358                         break;
 359                 case 'Y':
 360                         options.forward_x11 = 1;
 361                         options.forward_x11_trusted = 1;
 362                         break;
 363                 case 'g':
 364                         options.gateway_ports = 1;
 365                         break;
 366                 case 'O':
 367                         if (stdio_forward_host != NULL)
 368                                 fatal("Cannot specify multiplexing "
 369                                     "command with -W");
 370                         else if (muxclient_command != 0)
 371                                 fatal("Multiplexing command already specified");
 372                         if (strcmp(optarg, "check") == 0)
 373                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 374                         else if (strcmp(optarg, "forward") == 0)
 375                                 muxclient_command = SSHMUX_COMMAND_FORWARD;
 376                         else if (strcmp(optarg, "exit") == 0)
 377                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 378                         else if (strcmp(optarg, "stop") == 0)
 379                                 muxclient_command = SSHMUX_COMMAND_STOP;
 380                         else if (strcmp(optarg, "cancel") == 0)
 381                                 muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
 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                         /* ensure that the user doesn't try to backdoor a */
 583                         /* null cipher switch on an interactive session */
 584                         /* so explicitly disable it no matter what */
 585                         options.none_switch=0;
 586                         break;
 587                 case 'o':
 588                         dummy = 1;
 589                         line = xstrdup(optarg);
 590                         if (process_config_line(&options, host ? host : "",
 591                             line, "command-line", 0, &dummy) != 0)
 592                                 exit(255);
 593                         xfree(line);
 594                         break;
 595                 case 's':
 596                         subsystem_flag = 1;
 597                         break;
 598                 case 'S':
 599                         if (options.control_path != NULL)
 600                                 free(options.control_path);
 601                         options.control_path = xstrdup(optarg);
 602                         break;
 603                 case 'b':
 604                         options.bind_address = optarg;
 605                         break;
 606                 case 'F':
 607                         config = optarg;
 608                         break;
 609                 default:
 610                         usage();
 611                 }
 612         }
 613
 614         ac -= optind;
 615         av += optind;
 616
 617         if (ac > 0 && !host) {
 618                 if (strrchr(*av, '@')) {
 619                         p = xstrdup(*av);
 620                         cp = strrchr(p, '@');
 621                         if (cp == NULL || cp == p)
 622                                 usage();
 623                         options.user = p;
 624                         *cp = '\0';
 625                         host = ++cp;
 626                 } else
 627                         host = *av;
 628                 if (ac > 1) {
 629                         optind = optreset = 1;
 630                         goto again;
 631                 }
 632                 ac--, av++;
 633         }
 634
 635         /* Check that we got a host name. */
 636         if (!host)
 637                 usage();
 638
 639         OpenSSL_add_all_algorithms();
 640         ERR_load_crypto_strings();
 641
 642         /* Initialize the command to execute on remote host. */
 643         buffer_init(&command);
 644
 645         /*
 646          * Save the command to execute on the remote host in a buffer. There
 647          * is no limit on the length of the command, except by the maximum
 648          * packet size.  Also sets the tty flag if there is no command.
 649          */
 650         if (!ac) {
 651                 /* No command specified - execute shell on a tty. */
 652                 if (subsystem_flag) {
 653                         fprintf(stderr,
 654                             "You must specify a subsystem to invoke.\n");
 655                         usage();
 656                 }
 657         } else {
 658                 /* A command has been specified.  Store it into the buffer. */
 659                 for (i = 0; i < ac; i++) {
 660                         if (i)
 661                                 buffer_append(&command, " ", 1);
 662                         buffer_append(&command, av[i], strlen(av[i]));
 663                 }
 664         }
 665
 666         /* Cannot fork to background if no command. */
 667         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 668             !no_shell_flag)
 669                 fatal("Cannot fork into background without a command "
 670                     "to execute.");
 671
 672         /*
 673          * Initialize "log" output.  Since we are the client all output
 674          * actually goes to stderr.
 675          */
 676         log_init(argv0,
 677             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 678             SYSLOG_FACILITY_USER, !use_syslog);
 679
 680         /*
 681          * Read per-user configuration file.  Ignore the system wide config
 682          * file if the user specifies a config file on the command line.
 683          */
 684         if (config != NULL) {
 685                 if (!read_config_file(config, host, &options, 0))
 686                         fatal("Can't open user config file %.100s: "
 687                             "%.100s", config, strerror(errno));
 688         } else {
 689                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 690                     _PATH_SSH_USER_CONFFILE);
 691                 if (r > 0 && (size_t)r < sizeof(buf))
 692                         (void)read_config_file(buf, host, &options, 1);
 693
 694                 /* Read systemwide configuration file after user config. */
 695                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 696                     &options, 0);
 697         }
 698
 699         /* Fill configuration defaults. */
 700         fill_default_options(&options);
 701
 702         channel_set_af(options.address_family);
 703
 704         /* reinit */
 705         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 706
 707         if (options.request_tty == REQUEST_TTY_YES ||
 708             options.request_tty == REQUEST_TTY_FORCE)
 709                 tty_flag = 1;
 710
 711         /* Allocate a tty by default if no command specified. */
 712         if (buffer_len(&command) == 0)
 713                 tty_flag = options.request_tty != REQUEST_TTY_NO;
 714
 715         /* Force no tty */
 716         if (options.request_tty == REQUEST_TTY_NO || muxclient_command != 0)
 717                 tty_flag = 0;
 718         /* Do not allocate a tty if stdin is not a tty. */
 719         if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
 720             options.request_tty != REQUEST_TTY_FORCE) {
 721                 if (tty_flag)
 722                         logit("Pseudo-terminal will not be allocated because "
 723                             "stdin is not a terminal.");
 724                 tty_flag = 0;
 725         }
 726
 727         seed_rng();
 728
 729         if (options.user == NULL)
 730                 options.user = xstrdup(pw->pw_name);
 731
 732         /* Get default port if port has not been set. */
 733         if (options.port == 0) {
 734                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 735                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 736         }
 737
 738         /* preserve host name given on command line for %n expansion */
 739         host_arg = host;
 740         if (options.hostname != NULL) {
 741                 host = percent_expand(options.hostname,
 742                     "h", host, (char *)NULL);
 743         }
 744
 745         if (gethostname(thishost, sizeof(thishost)) == -1)
 746                 fatal("gethostname: %s", strerror(errno));
 747         strlcpy(shorthost, thishost, sizeof(shorthost));
 748         shorthost[strcspn(thishost, ".")] = '\0';
 749         snprintf(portstr, sizeof(portstr), "%d", options.port);
 750
 751         if (options.local_command != NULL) {
 752                 debug3("expanding LocalCommand: %s", options.local_command);
 753                 cp = options.local_command;
 754                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 755                     "h", host, "l", thishost, "n", host_arg, "r", options.user,
 756                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 757                     (char *)NULL);
 758                 debug3("expanded LocalCommand: %s", options.local_command);
 759                 xfree(cp);
 760         }
 761
 762         /* force lowercase for hostkey matching */
 763         if (options.host_key_alias != NULL) {
 764                 for (p = options.host_key_alias; *p; p++)
 765                         if (isupper(*p))
 766                                 *p = (char)tolower(*p);
 767         }
 768
 769         if (options.proxy_command != NULL &&
 770             strcmp(options.proxy_command, "none") == 0) {
 771                 xfree(options.proxy_command);
 772                 options.proxy_command = NULL;
 773         }
 774         if (options.control_path != NULL &&
 775             strcmp(options.control_path, "none") == 0) {
 776                 xfree(options.control_path);
 777                 options.control_path = NULL;
 778         }
 779
 780         if (options.control_path != NULL) {
 781                 cp = tilde_expand_filename(options.control_path,
 782                     original_real_uid);
 783                 xfree(options.control_path);
 784                 options.control_path = percent_expand(cp, "h", host,
 785                     "l", thishost, "n", host_arg, "r", options.user,
 786                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 787                     (char *)NULL);
 788                 xfree(cp);
 789         }
 790         if (muxclient_command != 0 && options.control_path == NULL)
 791                 fatal("No ControlPath specified for \"-O\" command");
 792         if (options.control_path != NULL)
 793                 muxclient(options.control_path);
 794
 795         timeout_ms = options.connection_timeout * 1000;
 796
 797         /* Open a connection to the remote host. */
 798         if (ssh_connect(host, &hostaddr, options.port,
 799             options.address_family, options.connection_attempts, &timeout_ms,
 800             options.tcp_keep_alive,
 801 #ifdef HAVE_CYGWIN
 802             options.use_privileged_port,
 803 #else
 804             original_effective_uid == 0 && options.use_privileged_port,
 805 #endif
 806             options.proxy_command) != 0)
 807                 exit(255);
 808
 809         if (timeout_ms > 0)
 810                 debug3("timeout: %d ms remain after connect", timeout_ms);
 811
 812         /*
 813          * If we successfully made the connection, load the host private key
 814          * in case we will need it later for combined rsa-rhosts
 815          * authentication. This must be done before releasing extra
 816          * privileges, because the file is only readable by root.
 817          * If we cannot access the private keys, load the public keys
 818          * instead and try to execute the ssh-keysign helper instead.
 819          */
 820         sensitive_data.nkeys = 0;
 821         sensitive_data.keys = NULL;
 822         sensitive_data.external_keysign = 0;
 823         if (options.rhosts_rsa_authentication ||
 824             options.hostbased_authentication) {
 825                 sensitive_data.nkeys = 7;
 826                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 827                     sizeof(Key));
 828                 for (i = 0; i < sensitive_data.nkeys; i++)
 829                         sensitive_data.keys[i] = NULL;
 830
 831                 PRIV_START;
 832                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 833                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 834                 sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
 835                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 836 #ifdef OPENSSL_HAS_ECC
 837                 sensitive_data.keys[2] = key_load_private_cert(KEY_ECDSA,
 838                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
 839 #endif
 840                 sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
 841                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 842                 sensitive_data.keys[4] = key_load_private_type(KEY_DSA,
 843                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 844 #ifdef OPENSSL_HAS_ECC
 845                 sensitive_data.keys[5] = key_load_private_type(KEY_ECDSA,
 846                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
 847 #endif
 848                 sensitive_data.keys[6] = key_load_private_type(KEY_RSA,
 849                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 850                 PRIV_END;
 851
 852                 if (options.hostbased_authentication == 1 &&
 853                     sensitive_data.keys[0] == NULL &&
 854                     sensitive_data.keys[4] == NULL &&
 855                     sensitive_data.keys[5] == NULL &&
 856                     sensitive_data.keys[6] == NULL) {
 857                         sensitive_data.keys[1] = key_load_cert(
 858                             _PATH_HOST_DSA_KEY_FILE);
 859 #ifdef OPENSSL_HAS_ECC
 860                         sensitive_data.keys[2] = key_load_cert(
 861                             _PATH_HOST_ECDSA_KEY_FILE);
 862 #endif
 863                         sensitive_data.keys[3] = key_load_cert(
 864                             _PATH_HOST_RSA_KEY_FILE);
 865                         sensitive_data.keys[4] = key_load_public(
 866                             _PATH_HOST_DSA_KEY_FILE, NULL);
 867 #ifdef OPENSSL_HAS_ECC
 868                         sensitive_data.keys[5] = key_load_public(
 869                             _PATH_HOST_ECDSA_KEY_FILE, NULL);
 870 #endif
 871                         sensitive_data.keys[6] = key_load_public(
 872                             _PATH_HOST_RSA_KEY_FILE, NULL);
 873                         sensitive_data.external_keysign = 1;
 874                 }
 875         }
 876         /*
 877          * Get rid of any extra privileges that we may have.  We will no
 878          * longer need them.  Also, extra privileges could make it very hard
 879          * to read identity files and other non-world-readable files from the
 880          * user's home directory if it happens to be on a NFS volume where
 881          * root is mapped to nobody.
 882          */
 883         if (original_effective_uid == 0) {
 884                 PRIV_START;
 885                 permanently_set_uid(pw);
 886         }
 887
 888         /*
 889          * Now that we are back to our own permissions, create ~/.ssh
 890          * directory if it doesn't already exist.
 891          */
 892         if (config == NULL) {
 893                 r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
 894                     strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 895                 if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
 896 #ifdef WITH_SELINUX
 897                         ssh_selinux_setfscreatecon(buf);
 898 #endif
 899                         if (mkdir(buf, 0700) < 0)
 900                                 error("Could not create directory '%.200s'.",
 901                                     buf);
 902 #ifdef WITH_SELINUX
 903                         ssh_selinux_setfscreatecon(NULL);
 904 #endif
 905                 }
 906         }
 907         /* load options.identity_files */
 908         load_public_identity_files();
 909
 910         /* Expand ~ in known host file names. */
 911         tilde_expand_paths(options.system_hostfiles,
 912             options.num_system_hostfiles);
 913         tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
 914
 915         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 916         signal(SIGCHLD, main_sigchld_handler);
 917
 918         /* Log into the remote system.  Never returns if the login fails. */
 919         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 920             options.port, pw, timeout_ms);
 921
 922         if (packet_connection_is_on_socket()) {
 923                 verbose("Authenticated to %s ([%s]:%d).", host,
 924                     get_remote_ipaddr(), get_remote_port());
 925         } else {
 926                 verbose("Authenticated to %s (via proxy).", host);
 927         }
 928
 929         /* We no longer need the private host keys.  Clear them now. */
 930         if (sensitive_data.nkeys != 0) {
 931                 for (i = 0; i < sensitive_data.nkeys; i++) {
 932                         if (sensitive_data.keys[i] != NULL) {
 933                                 /* Destroys contents safely */
 934                                 debug3("clear hostkey %d", i);
 935                                 key_free(sensitive_data.keys[i]);
 936                                 sensitive_data.keys[i] = NULL;
 937                         }
 938                 }
 939                 xfree(sensitive_data.keys);
 940         }
 941         for (i = 0; i < options.num_identity_files; i++) {
 942                 if (options.identity_files[i]) {
 943                         xfree(options.identity_files[i]);
 944                         options.identity_files[i] = NULL;
 945                 }
 946                 if (options.identity_keys[i]) {
 947                         key_free(options.identity_keys[i]);
 948                         options.identity_keys[i] = NULL;
 949                 }
 950         }
 951
 952         exit_status = compat20 ? ssh_session2() : ssh_session();
 953         packet_close();
 954
 955         if (options.control_path != NULL && muxserver_sock != -1)
 956                 unlink(options.control_path);
 957
 958         /* Kill ProxyCommand if it is running. */
 959         ssh_kill_proxy_command();
 960
 961         return exit_status;
 962 }
 963
 964 static void
 965 control_persist_detach(void)
 966 {
 967         pid_t pid;
 968         int devnull;
 969
 970         debug("%s: backgrounding master process", __func__);
 971
 972         /*
 973          * master (current process) into the background, and make the
 974          * foreground process a client of the backgrounded master.
 975          */
 976         switch ((pid = fork())) {
 977         case -1:
 978                 fatal("%s: fork: %s", __func__, strerror(errno));
 979         case 0:
 980                 /* Child: master process continues mainloop */
 981                 break;
 982         default:
 983                 /* Parent: set up mux slave to connect to backgrounded master */
 984                 debug2("%s: background process is %ld", __func__, (long)pid);
 985                 stdin_null_flag = ostdin_null_flag;
 986                 options.request_tty = orequest_tty;
 987                 tty_flag = otty_flag;
 988                 close(muxserver_sock);
 989                 muxserver_sock = -1;
 990                 options.control_master = SSHCTL_MASTER_NO;
 991                 muxclient(options.control_path);
 992                 /* muxclient() doesn't return on success. */
 993                 fatal("Failed to connect to new control master");
 994         }
 995         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
 996                 error("%s: open(\"/dev/null\"): %s", __func__,
 997                     strerror(errno));
 998         } else {
 999                 if (dup2(devnull, STDIN_FILENO) == -1 ||
1000                     dup2(devnull, STDOUT_FILENO) == -1)
1001                         error("%s: dup2: %s", __func__, strerror(errno));
1002                 if (devnull > STDERR_FILENO)
1003                         close(devnull);
1004         }
1005         setproctitle("%s [mux]", options.control_path);
1006 }
1007
1008 /* Do fork() after authentication. Used by "ssh -f" */
1009 static void
1010 fork_postauth(void)
1011 {
1012         if (need_controlpersist_detach)
1013                 control_persist_detach();
1014         debug("forking to background");
1015         fork_after_authentication_flag = 0;
1016         if (daemon(1, 1) < 0)
1017                 fatal("daemon() failed: %.200s", strerror(errno));
1018 }
1019
1020 /* Callback for remote forward global requests */
1021 static void
1022 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
1023 {
1024         Forward *rfwd = (Forward *)ctxt;
1025
1026         /* XXX verbose() on failure? */
1027         debug("remote forward %s for: listen %d, connect %s:%d",
1028             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1029             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
1030         if (rfwd->listen_port == 0) {
1031                 if (type == SSH2_MSG_REQUEST_SUCCESS) {
1032                         rfwd->allocated_port = packet_get_int();
1033                         logit("Allocated port %u for remote forward to %s:%d",
1034                             rfwd->allocated_port,
1035                             rfwd->connect_host, rfwd->connect_port);
1036                         channel_update_permitted_opens(rfwd->handle,
1037                             rfwd->allocated_port);
1038                 } else {
1039                         channel_update_permitted_opens(rfwd->handle, -1);
1040                 }
1041         }
1042
1043         if (type == SSH2_MSG_REQUEST_FAILURE) {
1044                 if (options.exit_on_forward_failure)
1045                         fatal("Error: remote port forwarding failed for "
1046                             "listen port %d", rfwd->listen_port);
1047                 else
1048                         logit("Warning: remote port forwarding failed for "
1049                             "listen port %d", rfwd->listen_port);
1050         }
1051         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1052                 debug("All remote forwarding requests processed");
1053                 if (fork_after_authentication_flag)
1054                         fork_postauth();
1055         }
1056 }
1057
1058 static void
1059 client_cleanup_stdio_fwd(int id, void *arg)
1060 {
1061         debug("stdio forwarding: done");
1062         cleanup_exit(0);
1063 }
1064
1065 static void
1066 ssh_init_stdio_forwarding(void)
1067 {
1068         Channel *c;
1069         int in, out;
1070
1071         if (stdio_forward_host == NULL)
1072                 return;
1073         if (!compat20)
1074                 fatal("stdio forwarding require Protocol 2");
1075
1076         debug3("%s: %s:%d", __func__, stdio_forward_host, stdio_forward_port);
1077
1078         if ((in = dup(STDIN_FILENO)) < 0 ||
1079             (out = dup(STDOUT_FILENO)) < 0)
1080                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1081         if ((c = channel_connect_stdio_fwd(stdio_forward_host,
1082             stdio_forward_port, in, out)) == NULL)
1083                 fatal("%s: channel_connect_stdio_fwd failed", __func__);
1084         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1085 }
1086
1087 static void
1088 ssh_init_forwarding(void)
1089 {
1090         int success = 0;
1091         int i;
1092
1093         /* Initiate local TCP/IP port forwardings. */
1094         for (i = 0; i < options.num_local_forwards; i++) {
1095                 debug("Local connections to %.200s:%d forwarded to remote "
1096                     "address %.200s:%d",
1097                     (options.local_forwards[i].listen_host == NULL) ?
1098                     (options.gateway_ports ? "*" : "LOCALHOST") :
1099                     options.local_forwards[i].listen_host,
1100                     options.local_forwards[i].listen_port,
1101                     options.local_forwards[i].connect_host,
1102                     options.local_forwards[i].connect_port);
1103                 success += channel_setup_local_fwd_listener(
1104                     options.local_forwards[i].listen_host,
1105                     options.local_forwards[i].listen_port,
1106                     options.local_forwards[i].connect_host,
1107                     options.local_forwards[i].connect_port,
1108                     options.gateway_ports);
1109         }
1110         if (i > 0 && success != i && options.exit_on_forward_failure)
1111                 fatal("Could not request local forwarding.");
1112         if (i > 0 && success == 0)
1113                 error("Could not request local forwarding.");
1114
1115         /* Initiate remote TCP/IP port forwardings. */
1116         for (i = 0; i < options.num_remote_forwards; i++) {
1117                 debug("Remote connections from %.200s:%d forwarded to "
1118                     "local address %.200s:%d",
1119                     (options.remote_forwards[i].listen_host == NULL) ?
1120                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1121                     options.remote_forwards[i].listen_port,
1122                     options.remote_forwards[i].connect_host,
1123                     options.remote_forwards[i].connect_port);
1124                 options.remote_forwards[i].handle =
1125                     channel_request_remote_forwarding(
1126                     options.remote_forwards[i].listen_host,
1127                     options.remote_forwards[i].listen_port,
1128                     options.remote_forwards[i].connect_host,
1129                     options.remote_forwards[i].connect_port);
1130                 if (options.remote_forwards[i].handle < 0) {
1131                         if (options.exit_on_forward_failure)
1132                                 fatal("Could not request remote forwarding.");
1133                         else
1134                                 logit("Warning: Could not request remote "
1135                                     "forwarding.");
1136                 } else {
1137                         client_register_global_confirm(ssh_confirm_remote_forward,
1138                             &options.remote_forwards[i]);
1139                 }
1140         }
1141
1142         /* Initiate tunnel forwarding. */
1143         if (options.tun_open != SSH_TUNMODE_NO) {
1144                 if (client_request_tun_fwd(options.tun_open,
1145                     options.tun_local, options.tun_remote) == -1) {
1146                         if (options.exit_on_forward_failure)
1147                                 fatal("Could not request tunnel forwarding.");
1148                         else
1149                                 error("Could not request tunnel forwarding.");
1150                 }
1151         }
1152 }
1153
1154 static void
1155 check_agent_present(void)
1156 {
1157         if (options.forward_agent) {
1158                 /* Clear agent forwarding if we don't have an agent. */
1159                 if (!ssh_agent_present())
1160                         options.forward_agent = 0;
1161         }
1162 }
1163
1164 static int
1165 ssh_session(void)
1166 {
1167         int type;
1168         int interactive = 0;
1169         int have_tty = 0;
1170         struct winsize ws;
1171         char *cp;
1172         const char *display;
1173
1174         /* Enable compression if requested. */
1175         if (options.compression) {
1176                 debug("Requesting compression at level %d.",
1177                     options.compression_level);
1178
1179                 if (options.compression_level < 1 ||
1180                     options.compression_level > 9)
1181                         fatal("Compression level must be from 1 (fast) to "
1182                             "9 (slow, best).");
1183
1184                 /* Send the request. */
1185                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1186                 packet_put_int(options.compression_level);
1187                 packet_send();
1188                 packet_write_wait();
1189                 type = packet_read();
1190                 if (type == SSH_SMSG_SUCCESS)
1191                         packet_start_compression(options.compression_level);
1192                 else if (type == SSH_SMSG_FAILURE)
1193                         logit("Warning: Remote host refused compression.");
1194                 else
1195                         packet_disconnect("Protocol error waiting for "
1196                             "compression response.");
1197         }
1198         /* Allocate a pseudo tty if appropriate. */
1199         if (tty_flag) {
1200                 debug("Requesting pty.");
1201
1202                 /* Start the packet. */
1203                 packet_start(SSH_CMSG_REQUEST_PTY);
1204
1205                 /* Store TERM in the packet.  There is no limit on the
1206                    length of the string. */
1207                 cp = getenv("TERM");
1208                 if (!cp)
1209                         cp = "";
1210                 packet_put_cstring(cp);
1211
1212                 /* Store window size in the packet. */
1213                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1214                         memset(&ws, 0, sizeof(ws));
1215                 packet_put_int((u_int)ws.ws_row);
1216                 packet_put_int((u_int)ws.ws_col);
1217                 packet_put_int((u_int)ws.ws_xpixel);
1218                 packet_put_int((u_int)ws.ws_ypixel);
1219
1220                 /* Store tty modes in the packet. */
1221                 tty_make_modes(fileno(stdin), NULL);
1222
1223                 /* Send the packet, and wait for it to leave. */
1224                 packet_send();
1225                 packet_write_wait();
1226
1227                 /* Read response from the server. */
1228                 type = packet_read();
1229                 if (type == SSH_SMSG_SUCCESS) {
1230                         interactive = 1;
1231                         have_tty = 1;
1232                 } else if (type == SSH_SMSG_FAILURE)
1233                         logit("Warning: Remote host failed or refused to "
1234                             "allocate a pseudo tty.");
1235                 else
1236                         packet_disconnect("Protocol error waiting for pty "
1237                             "request response.");
1238         }
1239         /* Request X11 forwarding if enabled and DISPLAY is set. */
1240         display = getenv("DISPLAY");
1241         if (options.forward_x11 && display != NULL) {
1242                 char *proto, *data;
1243                 /* Get reasonable local authentication information. */
1244                 client_x11_get_proto(display, options.xauth_location,
1245                     options.forward_x11_trusted,
1246                     options.forward_x11_timeout,
1247                     &proto, &data);
1248                 /* Request forwarding with authentication spoofing. */
1249                 debug("Requesting X11 forwarding with authentication "
1250                     "spoofing.");
1251                 x11_request_forwarding_with_spoofing(0, display, proto,
1252                     data, 0);
1253                 /* Read response from the server. */
1254                 type = packet_read();
1255                 if (type == SSH_SMSG_SUCCESS) {
1256                         interactive = 1;
1257                 } else if (type == SSH_SMSG_FAILURE) {
1258                         logit("Warning: Remote host denied X11 forwarding.");
1259                 } else {
1260                         packet_disconnect("Protocol error waiting for X11 "
1261                             "forwarding");
1262                 }
1263         }
1264         /* Tell the packet module whether this is an interactive session. */
1265         packet_set_interactive(interactive,
1266             options.ip_qos_interactive, options.ip_qos_bulk);
1267
1268         /* Request authentication agent forwarding if appropriate. */
1269         check_agent_present();
1270
1271         if (options.forward_agent) {
1272                 debug("Requesting authentication agent forwarding.");
1273                 auth_request_forwarding();
1274
1275                 /* Read response from the server. */
1276                 type = packet_read();
1277                 packet_check_eom();
1278                 if (type != SSH_SMSG_SUCCESS)
1279                         logit("Warning: Remote host denied authentication agent forwarding.");
1280         }
1281
1282         /* Initiate port forwardings. */
1283         ssh_init_stdio_forwarding();
1284         ssh_init_forwarding();
1285
1286         /* Execute a local command */
1287         if (options.local_command != NULL &&
1288             options.permit_local_command)
1289                 ssh_local_cmd(options.local_command);
1290
1291         /*
1292          * If requested and we are not interested in replies to remote
1293          * forwarding requests, then let ssh continue in the background.
1294          */
1295         if (fork_after_authentication_flag) {
1296                 if (options.exit_on_forward_failure &&
1297                     options.num_remote_forwards > 0) {
1298                         debug("deferring postauth fork until remote forward "
1299                             "confirmation received");
1300                 } else
1301                         fork_postauth();
1302         }
1303
1304         /*
1305          * If a command was specified on the command line, execute the
1306          * command now. Otherwise request the server to start a shell.
1307          */
1308         if (buffer_len(&command) > 0) {
1309                 int len = buffer_len(&command);
1310                 if (len > 900)
1311                         len = 900;
1312                 debug("Sending command: %.*s", len,
1313                     (u_char *)buffer_ptr(&command));
1314                 packet_start(SSH_CMSG_EXEC_CMD);
1315                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1316                 packet_send();
1317                 packet_write_wait();
1318         } else {
1319                 debug("Requesting shell.");
1320                 packet_start(SSH_CMSG_EXEC_SHELL);
1321                 packet_send();
1322                 packet_write_wait();
1323         }
1324
1325         /* Enter the interactive session. */
1326         return client_loop(have_tty, tty_flag ?
1327             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1328 }
1329
1330 /* request pty/x11/agent/tcpfwd/shell for channel */
1331 static void
1332 ssh_session2_setup(int id, int success, void *arg)
1333 {
1334         extern char **environ;
1335         const char *display;
1336         int interactive = tty_flag;
1337
1338         if (!success)
1339                 return; /* No need for error message, channels code sens one */
1340
1341         display = getenv("DISPLAY");
1342         if (options.forward_x11 && display != NULL) {
1343                 char *proto, *data;
1344                 /* Get reasonable local authentication information. */
1345                 client_x11_get_proto(display, options.xauth_location,
1346                     options.forward_x11_trusted,
1347                     options.forward_x11_timeout, &proto, &data);
1348                 /* Request forwarding with authentication spoofing. */
1349                 debug("Requesting X11 forwarding with authentication "
1350                     "spoofing.");
1351                 x11_request_forwarding_with_spoofing(id, display, proto,
1352                     data, 1);
1353                 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
1354                 /* XXX exit_on_forward_failure */
1355                 interactive = 1;
1356         }
1357
1358         check_agent_present();
1359         if (options.forward_agent) {
1360                 debug("Requesting authentication agent forwarding.");
1361                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1362                 packet_send();
1363         }
1364
1365         /* Tell the packet module whether this is an interactive session. */
1366         packet_set_interactive(interactive,
1367             options.ip_qos_interactive, options.ip_qos_bulk);
1368
1369         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1370             NULL, fileno(stdin), &command, environ);
1371 }
1372
1373 /* open new channel for a session */
1374 static int
1375 ssh_session2_open(void)
1376 {
1377         Channel *c;
1378         int window, packetmax, in, out, err;
1379         int sock;
1380         int socksize;
1381         int socksizelen = sizeof(int);
1382
1383         if (stdin_null_flag) {
1384                 in = open(_PATH_DEVNULL, O_RDONLY);
1385         } else {
1386                 in = dup(STDIN_FILENO);
1387         }
1388         out = dup(STDOUT_FILENO);
1389         err = dup(STDERR_FILENO);
1390
1391         if (in < 0 || out < 0 || err < 0)
1392                 fatal("dup() in/out/err failed");
1393
1394         /* enable nonblocking unless tty */
1395         if (!isatty(in))
1396                 set_nonblock(in);
1397         if (!isatty(out))
1398                 set_nonblock(out);
1399         if (!isatty(err))
1400                 set_nonblock(err);
1401
1402         /* we need to check to see if what they want to do about buffer */
1403         /* sizes here. In a hpn to nonhpn connection we want to limit */
1404         /* the window size to something reasonable in case the far side */
1405         /* has the large window bug. In hpn to hpn connection we want to */
1406         /* use the max window size but allow the user to override it */
1407         /* lastly if they disabled hpn then use the ssh std window size */
1408
1409         /* so why don't we just do a getsockopt() here and set the */
1410         /* ssh window to that? In the case of a autotuning receive */
1411         /* window the window would get stuck at the initial buffer */
1412         /* size generally less than 96k. Therefore we need to set the */
1413         /* maximum ssh window size to the maximum hpn buffer size */
1414         /* unless the user has specifically set the tcprcvbufpoll */
1415         /* to no. In which case we *can* just set the window to the */
1416         /* minimum of the hpn buffer size and tcp receive buffer size */
1417
1418         if (tty_flag)
1419                 options.hpn_buffer_size = CHAN_SES_WINDOW_DEFAULT;
1420         else
1421                 options.hpn_buffer_size = 2*1024*1024;
1422
1423         if (datafellows & SSH_BUG_LARGEWINDOW)
1424         {
1425                 debug("HPN to Non-HPN Connection");
1426         }
1427         else
1428         {
1429                 if (options.tcp_rcv_buf_poll <= 0)
1430                 {
1431                         sock = socket(AF_INET, SOCK_STREAM, 0);
1432                         getsockopt(sock, SOL_SOCKET, SO_RCVBUF,
1433                                    &socksize, &socksizelen);
1434                         close(sock);
1435                         debug("socksize %d", socksize);
1436                         options.hpn_buffer_size = socksize;
1437                         debug ("HPNBufferSize set to TCP RWIN: %d", options.hpn_buffer_size);
1438                 }
1439                 else
1440                 {
1441                         if (options.tcp_rcv_buf > 0)
1442                         {
1443                                 /*create a socket but don't connect it */
1444                                 /* we use that the get the rcv socket size */
1445                                 sock = socket(AF_INET, SOCK_STREAM, 0);
1446                                 /* if they are using the tcp_rcv_buf option */
1447                                 /* attempt to set the buffer size to that */
1448                                 if (options.tcp_rcv_buf)
1449                                         setsockopt(sock, SOL_SOCKET, SO_RCVBUF, (void *)&options.tcp_rcv_buf,
1450                                                    sizeof(options.tcp_rcv_buf));
1451                                 getsockopt(sock, SOL_SOCKET, SO_RCVBUF,
1452                                            &socksize, &socksizelen);
1453                                 close(sock);
1454                                 debug("socksize %d", socksize);
1455                                 options.hpn_buffer_size = socksize;
1456                                 debug ("HPNBufferSize set to user TCPRcvBuf: %d", options.hpn_buffer_size);
1457                         }
1458                 }
1459
1460         }
1461
1462         debug("Final hpn_buffer_size = %d", options.hpn_buffer_size);
1463
1464         window = options.hpn_buffer_size;
1465
1466         channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1467
1468         packetmax = CHAN_SES_PACKET_DEFAULT;
1469         if (tty_flag) {
1470                 window = 4*CHAN_SES_PACKET_DEFAULT;
1471                 window >>= 1;
1472                 packetmax >>= 1;
1473         }
1474         c = channel_new(
1475             "session", SSH_CHANNEL_OPENING, in, out, err,
1476             window, packetmax, CHAN_EXTENDED_WRITE,
1477             "client-session", /*nonblock*/0);
1478         if ((options.tcp_rcv_buf_poll > 0) && (!options.hpn_disabled)) {
1479                 c->dynamic_window = 1;
1480                 debug ("Enabled Dynamic Window Scaling\n");
1481         }
1482         debug3("ssh_session2_open: channel_new: %d", c->self);
1483
1484         channel_send_open(c->self);
1485         if (!no_shell_flag)
1486                 channel_register_open_confirm(c->self,
1487                     ssh_session2_setup, NULL);
1488
1489         return c->self;
1490 }
1491
1492 static int
1493 ssh_session2(void)
1494 {
1495         int id = -1;
1496
1497         /* XXX should be pre-session */
1498         if (!options.control_persist)
1499                 ssh_init_stdio_forwarding();
1500         ssh_init_forwarding();
1501
1502         /* Start listening for multiplex clients */
1503         muxserver_listen();
1504
1505         /*
1506          * If we are in control persist mode and have a working mux listen
1507          * socket, then prepare to background ourselves and have a foreground
1508          * client attach as a control slave.
1509          * NB. we must save copies of the flags that we override for
1510          * the backgrounding, since we defer attachment of the slave until
1511          * after the connection is fully established (in particular,
1512          * async rfwd replies have been received for ExitOnForwardFailure).
1513          */
1514         if (options.control_persist && muxserver_sock != -1) {
1515                 ostdin_null_flag = stdin_null_flag;
1516                 ono_shell_flag = no_shell_flag;
1517                 orequest_tty = options.request_tty;
1518                 otty_flag = tty_flag;
1519                 stdin_null_flag = 1;
1520                 no_shell_flag = 1;
1521                 tty_flag = 0;
1522                 if (!fork_after_authentication_flag)
1523                         need_controlpersist_detach = 1;
1524                 fork_after_authentication_flag = 1;
1525         }
1526         /*
1527          * ControlPersist mux listen socket setup failed, attempt the
1528          * stdio forward setup that we skipped earlier.
1529          */
1530         if (options.control_persist && muxserver_sock == -1)
1531                 ssh_init_stdio_forwarding();
1532
1533         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1534                 id = ssh_session2_open();
1535
1536         /* If we don't expect to open a new session, then disallow it */
1537         if (options.control_master == SSHCTL_MASTER_NO &&
1538             (datafellows & SSH_NEW_OPENSSH)) {
1539                 debug("Requesting no-more-sessions@openssh.com");
1540                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1541                 packet_put_cstring("no-more-sessions@openssh.com");
1542                 packet_put_char(0);
1543                 packet_send();
1544         }
1545
1546         /* Execute a local command */
1547         if (options.local_command != NULL &&
1548             options.permit_local_command)
1549                 ssh_local_cmd(options.local_command);
1550
1551         /*
1552          * If requested and we are not interested in replies to remote
1553          * forwarding requests, then let ssh continue in the background.
1554          */
1555         if (fork_after_authentication_flag) {
1556                 if (options.exit_on_forward_failure &&
1557                     options.num_remote_forwards > 0) {
1558                         debug("deferring postauth fork until remote forward "
1559                             "confirmation received");
1560                 } else
1561                         fork_postauth();
1562         }
1563
1564         if (options.use_roaming)
1565                 request_roaming();
1566
1567         return client_loop(tty_flag, tty_flag ?
1568             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1569 }
1570
1571 static void
1572 load_public_identity_files(void)
1573 {
1574         char *filename, *cp, thishost[NI_MAXHOST];
1575         char *pwdir = NULL, *pwname = NULL;
1576         int i = 0;
1577         Key *public;
1578         struct passwd *pw;
1579         u_int n_ids;
1580         char *identity_files[SSH_MAX_IDENTITY_FILES];
1581         Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1582 #ifdef ENABLE_PKCS11
1583         Key **keys;
1584         int nkeys;
1585 #endif /* PKCS11 */
1586
1587         n_ids = 0;
1588         bzero(identity_files, sizeof(identity_files));
1589         bzero(identity_keys, sizeof(identity_keys));
1590
1591 #ifdef ENABLE_PKCS11
1592         if (options.pkcs11_provider != NULL &&
1593             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1594             (pkcs11_init(!options.batch_mode) == 0) &&
1595             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1596             &keys)) > 0) {
1597                 for (i = 0; i < nkeys; i++) {
1598                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1599                                 key_free(keys[i]);
1600                                 continue;
1601                         }
1602                         identity_keys[n_ids] = keys[i];
1603                         identity_files[n_ids] =
1604                             xstrdup(options.pkcs11_provider); /* XXX */
1605                         n_ids++;
1606                 }
1607                 xfree(keys);
1608         }
1609 #endif /* ENABLE_PKCS11 */
1610         if ((pw = getpwuid(original_real_uid)) == NULL)
1611                 fatal("load_public_identity_files: getpwuid failed");
1612         pwname = xstrdup(pw->pw_name);
1613         pwdir = xstrdup(pw->pw_dir);
1614         if (gethostname(thishost, sizeof(thishost)) == -1)
1615                 fatal("load_public_identity_files: gethostname: %s",
1616                     strerror(errno));
1617         for (i = 0; i < options.num_identity_files; i++) {
1618                 if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1619                         xfree(options.identity_files[i]);
1620                         continue;
1621                 }
1622                 cp = tilde_expand_filename(options.identity_files[i],
1623                     original_real_uid);
1624                 filename = percent_expand(cp, "d", pwdir,
1625                     "u", pwname, "l", thishost, "h", host,
1626                     "r", options.user, (char *)NULL);
1627                 xfree(cp);
1628                 public = key_load_public(filename, NULL);
1629                 debug("identity file %s type %d", filename,
1630                     public ? public->type : -1);
1631                 xfree(options.identity_files[i]);
1632                 identity_files[n_ids] = filename;
1633                 identity_keys[n_ids] = public;
1634
1635                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
1636                         continue;
1637
1638                 /* Try to add the certificate variant too */
1639                 xasprintf(&cp, "%s-cert", filename);
1640                 public = key_load_public(cp, NULL);
1641                 debug("identity file %s type %d", cp,
1642                     public ? public->type : -1);
1643                 if (public == NULL) {
1644                         xfree(cp);
1645                         continue;
1646                 }
1647                 if (!key_is_cert(public)) {
1648                         debug("%s: key %s type %s is not a certificate",
1649                             __func__, cp, key_type(public));
1650                         key_free(public);
1651                         xfree(cp);
1652                         continue;
1653                 }
1654                 identity_keys[n_ids] = public;
1655                 /* point to the original path, most likely the private key */
1656                 identity_files[n_ids] = xstrdup(filename);
1657                 n_ids++;
1658         }
1659         options.num_identity_files = n_ids;
1660         memcpy(options.identity_files, identity_files, sizeof(identity_files));
1661         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
1662
1663         bzero(pwname, strlen(pwname));
1664         xfree(pwname);
1665         bzero(pwdir, strlen(pwdir));
1666         xfree(pwdir);
1667 }
1668
1669 static void
1670 main_sigchld_handler(int sig)
1671 {
1672         int save_errno = errno;
1673         pid_t pid;
1674         int status;
1675
1676         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
1677             (pid < 0 && errno == EINTR))
1678                 ;
1679
1680         signal(sig, main_sigchld_handler);
1681         errno = save_errno;
1682 }
1683