crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.371 2013/02/17 23:16:57 dtucker 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 if (strcmp(optarg, "cancel") == 0)
 383                                 muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
 384                         else
 385                                 fatal("Invalid multiplex command.");
 386                         break;
 387                 case 'P':       /* deprecated */
 388                         options.use_privileged_port = 0;
 389                         break;
 390                 case 'a':
 391                         options.forward_agent = 0;
 392                         break;
 393                 case 'A':
 394                         options.forward_agent = 1;
 395                         break;
 396                 case 'k':
 397                         options.gss_deleg_creds = 0;
 398                         break;
 399                 case 'K':
 400                         options.gss_authentication = 1;
 401                         options.gss_deleg_creds = 1;
 402                         break;
 403                 case 'i':
 404                         if (stat(optarg, &st) < 0) {
 405                                 fprintf(stderr, "Warning: Identity file %s "
 406                                     "not accessible: %s.\n", optarg,
 407                                     strerror(errno));
 408                                 break;
 409                         }
 410                         add_identity_file(&options, NULL, optarg, 1);
 411                         break;
 412                 case 'I':
 413 #ifdef ENABLE_PKCS11
 414                         options.pkcs11_provider = xstrdup(optarg);
 415 #else
 416                         fprintf(stderr, "no support for PKCS#11.\n");
 417 #endif
 418                         break;
 419                 case 't':
 420                         if (options.request_tty == REQUEST_TTY_YES)
 421                                 options.request_tty = REQUEST_TTY_FORCE;
 422                         else
 423                                 options.request_tty = REQUEST_TTY_YES;
 424                         break;
 425                 case 'v':
 426                         if (debug_flag == 0) {
 427                                 debug_flag = 1;
 428                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 429                         } else {
 430                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 431                                         options.log_level++;
 432                                 break;
 433                         }
 434                         /* FALLTHROUGH */
 435                 case 'V':
 436                         if (options.version_addendum &&
 437                             *options.version_addendum != '\0')
 438                                 fprintf(stderr, "%s%s %s, %s\n", SSH_RELEASE,
 439                                     options.hpn_disabled ? "" : SSH_VERSION_HPN,
 440                                     options.version_addendum,
 441                                     SSLeay_version(SSLEAY_VERSION));
 442                         else
 443                                 fprintf(stderr, "%s%s, %s\n", SSH_RELEASE,
 444                                     options.hpn_disabled ? "" : SSH_VERSION_HPN,
 445                                     SSLeay_version(SSLEAY_VERSION));
 446                         if (opt == 'V')
 447                                 exit(0);
 448                         break;
 449                 case 'w':
 450                         if (options.tun_open == -1)
 451                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 452                         options.tun_local = a2tun(optarg, &options.tun_remote);
 453                         if (options.tun_local == SSH_TUNID_ERR) {
 454                                 fprintf(stderr,
 455                                     "Bad tun device '%s'\n", optarg);
 456                                 exit(255);
 457                         }
 458                         break;
 459                 case 'W':
 460                         if (stdio_forward_host != NULL)
 461                                 fatal("stdio forward already specified");
 462                         if (muxclient_command != 0)
 463                                 fatal("Cannot specify stdio forward with -O");
 464                         if (parse_forward(&fwd, optarg, 1, 0)) {
 465                                 stdio_forward_host = fwd.listen_host;
 466                                 stdio_forward_port = fwd.listen_port;
 467                                 xfree(fwd.connect_host);
 468                         } else {
 469                                 fprintf(stderr,
 470                                     "Bad stdio forwarding specification '%s'\n",
 471                                     optarg);
 472                                 exit(255);
 473                         }
 474                         options.request_tty = REQUEST_TTY_NO;
 475                         no_shell_flag = 1;
 476                         options.clear_forwardings = 1;
 477                         options.exit_on_forward_failure = 1;
 478                         break;
 479                 case 'q':
 480                         options.log_level = SYSLOG_LEVEL_QUIET;
 481                         break;
 482                 case 'e':
 483                         if (optarg[0] == '^' && optarg[2] == 0 &&
 484                             (u_char) optarg[1] >= 64 &&
 485                             (u_char) optarg[1] < 128)
 486                                 options.escape_char = (u_char) optarg[1] & 31;
 487                         else if (strlen(optarg) == 1)
 488                                 options.escape_char = (u_char) optarg[0];
 489                         else if (strcmp(optarg, "none") == 0)
 490                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 491                         else {
 492                                 fprintf(stderr, "Bad escape character '%s'.\n",
 493                                     optarg);
 494                                 exit(255);
 495                         }
 496                         break;
 497                 case 'c':
 498                         if (ciphers_valid(optarg)) {
 499                                 /* SSH2 only */
 500                                 options.ciphers = xstrdup(optarg);
 501                                 options.cipher = SSH_CIPHER_INVALID;
 502                         } else {
 503                                 /* SSH1 only */
 504                                 options.cipher = cipher_number(optarg);
 505                                 if (options.cipher == -1) {
 506                                         fprintf(stderr,
 507                                             "Unknown cipher type '%s'\n",
 508                                             optarg);
 509                                         exit(255);
 510                                 }
 511                                 if (options.cipher == SSH_CIPHER_3DES)
 512                                         options.ciphers = "3des-cbc";
 513                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 514                                         options.ciphers = "blowfish-cbc";
 515                                 else
 516                                         options.ciphers = (char *)-1;
 517                         }
 518                         break;
 519                 case 'm':
 520                         if (mac_valid(optarg))
 521                                 options.macs = xstrdup(optarg);
 522                         else {
 523                                 fprintf(stderr, "Unknown mac type '%s'\n",
 524                                     optarg);
 525                                 exit(255);
 526                         }
 527                         break;
 528                 case 'M':
 529                         if (options.control_master == SSHCTL_MASTER_YES)
 530                                 options.control_master = SSHCTL_MASTER_ASK;
 531                         else
 532                                 options.control_master = SSHCTL_MASTER_YES;
 533                         break;
 534                 case 'p':
 535                         options.port = a2port(optarg);
 536                         if (options.port <= 0) {
 537                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 538                                 exit(255);
 539                         }
 540                         break;
 541                 case 'l':
 542                         options.user = optarg;
 543                         break;
 544
 545                 case 'L':
 546                         if (parse_forward(&fwd, optarg, 0, 0))
 547                                 add_local_forward(&options, &fwd);
 548                         else {
 549                                 fprintf(stderr,
 550                                     "Bad local forwarding specification '%s'\n",
 551                                     optarg);
 552                                 exit(255);
 553                         }
 554                         break;
 555
 556                 case 'R':
 557                         if (parse_forward(&fwd, optarg, 0, 1)) {
 558                                 add_remote_forward(&options, &fwd);
 559                         } else {
 560                                 fprintf(stderr,
 561                                     "Bad remote forwarding specification "
 562                                     "'%s'\n", optarg);
 563                                 exit(255);
 564                         }
 565                         break;
 566
 567                 case 'D':
 568                         if (parse_forward(&fwd, optarg, 1, 0)) {
 569                                 add_local_forward(&options, &fwd);
 570                         } else {
 571                                 fprintf(stderr,
 572                                     "Bad dynamic forwarding specification "
 573                                     "'%s'\n", optarg);
 574                                 exit(255);
 575                         }
 576                         break;
 577
 578                 case 'C':
 579                         options.compression = 1;
 580                         break;
 581                 case 'N':
 582                         no_shell_flag = 1;
 583                         options.request_tty = REQUEST_TTY_NO;
 584                         break;
 585                 case 'T':
 586                         options.request_tty = REQUEST_TTY_NO;
 587 #ifdef  NONE_CIPHER_ENABLED
 588                         /*
 589                          * Ensure that the user does not try to backdoor a
 590                          * NONE cipher switch on an interactive session by
 591                          * explicitly disabling it if the user asks for a
 592                          * session without a tty.
 593                          */
 594                         options.none_switch = 0;
 595 #endif
 596                         break;
 597                 case 'o':
 598                         dummy = 1;
 599                         line = xstrdup(optarg);
 600                         if (process_config_line(&options, host ? host : "",
 601                             line, "command-line", 0, &dummy) != 0)
 602                                 exit(255);
 603                         xfree(line);
 604                         break;
 605                 case 's':
 606                         subsystem_flag = 1;
 607                         break;
 608                 case 'S':
 609                         if (options.control_path != NULL)
 610                                 free(options.control_path);
 611                         options.control_path = xstrdup(optarg);
 612                         break;
 613                 case 'b':
 614                         options.bind_address = optarg;
 615                         break;
 616                 case 'F':
 617                         config = optarg;
 618                         break;
 619                 default:
 620                         usage();
 621                 }
 622         }
 623
 624         ac -= optind;
 625         av += optind;
 626
 627         if (ac > 0 && !host) {
 628                 if (strrchr(*av, '@')) {
 629                         p = xstrdup(*av);
 630                         cp = strrchr(p, '@');
 631                         if (cp == NULL || cp == p)
 632                                 usage();
 633                         options.user = p;
 634                         *cp = '\0';
 635                         host = ++cp;
 636                 } else
 637                         host = *av;
 638                 if (ac > 1) {
 639                         optind = optreset = 1;
 640                         goto again;
 641                 }
 642                 ac--, av++;
 643         }
 644
 645         /* Check that we got a host name. */
 646         if (!host)
 647                 usage();
 648
 649         OpenSSL_add_all_algorithms();
 650         ERR_load_crypto_strings();
 651
 652         /* Initialize the command to execute on remote host. */
 653         buffer_init(&command);
 654
 655         /*
 656          * Save the command to execute on the remote host in a buffer. There
 657          * is no limit on the length of the command, except by the maximum
 658          * packet size.  Also sets the tty flag if there is no command.
 659          */
 660         if (!ac) {
 661                 /* No command specified - execute shell on a tty. */
 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         /*
 683          * Initialize "log" output.  Since we are the client all output
 684          * actually goes to stderr.
 685          */
 686         log_init(argv0,
 687             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 688             SYSLOG_FACILITY_USER, !use_syslog);
 689
 690         /*
 691          * Read per-user configuration file.  Ignore the system wide config
 692          * file if the user specifies a config file on the command line.
 693          */
 694         if (config != NULL) {
 695                 if (!read_config_file(config, host, &options, 0))
 696                         fatal("Can't open user config file %.100s: "
 697                             "%.100s", config, strerror(errno));
 698         } else {
 699                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 700                     _PATH_SSH_USER_CONFFILE);
 701                 if (r > 0 && (size_t)r < sizeof(buf))
 702                         (void)read_config_file(buf, host, &options, 1);
 703
 704                 /* Read systemwide configuration file after user config. */
 705                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 706                     &options, 0);
 707         }
 708
 709         /* Fill configuration defaults. */
 710         fill_default_options(&options);
 711
 712         channel_set_af(options.address_family);
 713
 714         /* reinit */
 715         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 716
 717         if (options.request_tty == REQUEST_TTY_YES ||
 718             options.request_tty == REQUEST_TTY_FORCE)
 719                 tty_flag = 1;
 720
 721         /* Allocate a tty by default if no command specified. */
 722         if (buffer_len(&command) == 0)
 723                 tty_flag = options.request_tty != REQUEST_TTY_NO;
 724
 725         /* Force no tty */
 726         if (options.request_tty == REQUEST_TTY_NO || muxclient_command != 0)
 727                 tty_flag = 0;
 728         /* Do not allocate a tty if stdin is not a tty. */
 729         if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
 730             options.request_tty != REQUEST_TTY_FORCE) {
 731                 if (tty_flag)
 732                         logit("Pseudo-terminal will not be allocated because "
 733                             "stdin is not a terminal.");
 734                 tty_flag = 0;
 735         }
 736
 737         seed_rng();
 738
 739         if (options.user == NULL)
 740                 options.user = xstrdup(pw->pw_name);
 741
 742         /* Get default port if port has not been set. */
 743         if (options.port == 0) {
 744                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 745                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 746         }
 747
 748         /* preserve host name given on command line for %n expansion */
 749         host_arg = host;
 750         if (options.hostname != NULL) {
 751                 host = percent_expand(options.hostname,
 752                     "h", host, (char *)NULL);
 753         }
 754
 755         if (gethostname(thishost, sizeof(thishost)) == -1)
 756                 fatal("gethostname: %s", strerror(errno));
 757         strlcpy(shorthost, thishost, sizeof(shorthost));
 758         shorthost[strcspn(thishost, ".")] = '\0';
 759         snprintf(portstr, sizeof(portstr), "%d", options.port);
 760
 761         if (options.local_command != NULL) {
 762                 debug3("expanding LocalCommand: %s", options.local_command);
 763                 cp = options.local_command;
 764                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 765                     "h", host, "l", thishost, "n", host_arg, "r", options.user,
 766                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 767                     (char *)NULL);
 768                 debug3("expanded LocalCommand: %s", options.local_command);
 769                 xfree(cp);
 770         }
 771
 772         /* Find canonic host name. */
 773         if (strchr(host, '.') == 0) {
 774                 struct addrinfo hints;
 775                 struct addrinfo *ai = NULL;
 776                 int errgai;
 777                 memset(&hints, 0, sizeof(hints));
 778                 hints.ai_family = options.address_family;
 779                 hints.ai_flags = AI_CANONNAME;
 780                 hints.ai_socktype = SOCK_STREAM;
 781                 errgai = getaddrinfo(host, NULL, &hints, &ai);
 782                 if (errgai == 0) {
 783                         if (ai->ai_canonname != NULL)
 784                                 host = xstrdup(ai->ai_canonname);
 785                         freeaddrinfo(ai);
 786                 }
 787         }
 788
 789         /* force lowercase for hostkey matching */
 790         if (options.host_key_alias != NULL) {
 791                 for (p = options.host_key_alias; *p; p++)
 792                         if (isupper(*p))
 793                                 *p = (char)tolower(*p);
 794         }
 795
 796         if (options.proxy_command != NULL &&
 797             strcmp(options.proxy_command, "none") == 0) {
 798                 xfree(options.proxy_command);
 799                 options.proxy_command = NULL;
 800         }
 801         if (options.control_path != NULL &&
 802             strcmp(options.control_path, "none") == 0) {
 803                 xfree(options.control_path);
 804                 options.control_path = NULL;
 805         }
 806
 807         if (options.control_path != NULL) {
 808                 cp = tilde_expand_filename(options.control_path,
 809                     original_real_uid);
 810                 xfree(options.control_path);
 811                 options.control_path = percent_expand(cp, "h", host,
 812                     "l", thishost, "n", host_arg, "r", options.user,
 813                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 814                     (char *)NULL);
 815                 xfree(cp);
 816         }
 817         if (muxclient_command != 0 && options.control_path == NULL)
 818                 fatal("No ControlPath specified for \"-O\" command");
 819         if (options.control_path != NULL)
 820                 muxclient(options.control_path);
 821
 822         timeout_ms = options.connection_timeout * 1000;
 823
 824         /* Open a connection to the remote host. */
 825         if (ssh_connect(host, &hostaddr, options.port,
 826             options.address_family, options.connection_attempts, &timeout_ms,
 827             options.tcp_keep_alive,
 828 #ifdef HAVE_CYGWIN
 829             options.use_privileged_port,
 830 #else
 831             original_effective_uid == 0 && options.use_privileged_port,
 832 #endif
 833             options.proxy_command) != 0)
 834                 exit(255);
 835
 836         if (timeout_ms > 0)
 837                 debug3("timeout: %d ms remain after connect", timeout_ms);
 838
 839         /*
 840          * If we successfully made the connection, load the host private key
 841          * in case we will need it later for combined rsa-rhosts
 842          * authentication. This must be done before releasing extra
 843          * privileges, because the file is only readable by root.
 844          * If we cannot access the private keys, load the public keys
 845          * instead and try to execute the ssh-keysign helper instead.
 846          */
 847         sensitive_data.nkeys = 0;
 848         sensitive_data.keys = NULL;
 849         sensitive_data.external_keysign = 0;
 850         if (options.rhosts_rsa_authentication ||
 851             options.hostbased_authentication) {
 852                 sensitive_data.nkeys = 7;
 853                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 854                     sizeof(Key));
 855                 for (i = 0; i < sensitive_data.nkeys; i++)
 856                         sensitive_data.keys[i] = NULL;
 857
 858                 PRIV_START;
 859                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 860                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 861                 sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
 862                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 863 #ifdef OPENSSL_HAS_ECC
 864                 sensitive_data.keys[2] = key_load_private_cert(KEY_ECDSA,
 865                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
 866 #endif
 867                 sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
 868                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 869                 sensitive_data.keys[4] = key_load_private_type(KEY_DSA,
 870                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 871 #ifdef OPENSSL_HAS_ECC
 872                 sensitive_data.keys[5] = key_load_private_type(KEY_ECDSA,
 873                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
 874 #endif
 875                 sensitive_data.keys[6] = key_load_private_type(KEY_RSA,
 876                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 877                 PRIV_END;
 878
 879                 if (options.hostbased_authentication == 1 &&
 880                     sensitive_data.keys[0] == NULL &&
 881                     sensitive_data.keys[4] == NULL &&
 882                     sensitive_data.keys[5] == NULL &&
 883                     sensitive_data.keys[6] == NULL) {
 884                         sensitive_data.keys[1] = key_load_cert(
 885                             _PATH_HOST_DSA_KEY_FILE);
 886 #ifdef OPENSSL_HAS_ECC
 887                         sensitive_data.keys[2] = key_load_cert(
 888                             _PATH_HOST_ECDSA_KEY_FILE);
 889 #endif
 890                         sensitive_data.keys[3] = key_load_cert(
 891                             _PATH_HOST_RSA_KEY_FILE);
 892                         sensitive_data.keys[4] = key_load_public(
 893                             _PATH_HOST_DSA_KEY_FILE, NULL);
 894 #ifdef OPENSSL_HAS_ECC
 895                         sensitive_data.keys[5] = key_load_public(
 896                             _PATH_HOST_ECDSA_KEY_FILE, NULL);
 897 #endif
 898                         sensitive_data.keys[6] = key_load_public(
 899                             _PATH_HOST_RSA_KEY_FILE, NULL);
 900                         sensitive_data.external_keysign = 1;
 901                 }
 902         }
 903         /*
 904          * Get rid of any extra privileges that we may have.  We will no
 905          * longer need them.  Also, extra privileges could make it very hard
 906          * to read identity files and other non-world-readable files from the
 907          * user's home directory if it happens to be on a NFS volume where
 908          * root is mapped to nobody.
 909          */
 910         if (original_effective_uid == 0) {
 911                 PRIV_START;
 912                 permanently_set_uid(pw);
 913         }
 914
 915         /*
 916          * Now that we are back to our own permissions, create ~/.ssh
 917          * directory if it doesn't already exist.
 918          */
 919         if (config == NULL) {
 920                 r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
 921                     strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 922                 if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
 923 #ifdef WITH_SELINUX
 924                         ssh_selinux_setfscreatecon(buf);
 925 #endif
 926                         if (mkdir(buf, 0700) < 0)
 927                                 error("Could not create directory '%.200s'.",
 928                                     buf);
 929 #ifdef WITH_SELINUX
 930                         ssh_selinux_setfscreatecon(NULL);
 931 #endif
 932                 }
 933         }
 934         /* load options.identity_files */
 935         load_public_identity_files();
 936
 937         /* Expand ~ in known host file names. */
 938         tilde_expand_paths(options.system_hostfiles,
 939             options.num_system_hostfiles);
 940         tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
 941
 942         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 943         signal(SIGCHLD, main_sigchld_handler);
 944
 945         /* Log into the remote system.  Never returns if the login fails. */
 946         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 947             options.port, pw, timeout_ms);
 948
 949         if (packet_connection_is_on_socket()) {
 950                 verbose("Authenticated to %s ([%s]:%d).", host,
 951                     get_remote_ipaddr(), get_remote_port());
 952         } else {
 953                 verbose("Authenticated to %s (via proxy).", host);
 954         }
 955
 956         /* We no longer need the private host keys.  Clear them now. */
 957         if (sensitive_data.nkeys != 0) {
 958                 for (i = 0; i < sensitive_data.nkeys; i++) {
 959                         if (sensitive_data.keys[i] != NULL) {
 960                                 /* Destroys contents safely */
 961                                 debug3("clear hostkey %d", i);
 962                                 key_free(sensitive_data.keys[i]);
 963                                 sensitive_data.keys[i] = NULL;
 964                         }
 965                 }
 966                 xfree(sensitive_data.keys);
 967         }
 968         for (i = 0; i < options.num_identity_files; i++) {
 969                 if (options.identity_files[i]) {
 970                         xfree(options.identity_files[i]);
 971                         options.identity_files[i] = NULL;
 972                 }
 973                 if (options.identity_keys[i]) {
 974                         key_free(options.identity_keys[i]);
 975                         options.identity_keys[i] = NULL;
 976                 }
 977         }
 978
 979         exit_status = compat20 ? ssh_session2() : ssh_session();
 980         packet_close();
 981
 982         if (options.control_path != NULL && muxserver_sock != -1)
 983                 unlink(options.control_path);
 984
 985         /* Kill ProxyCommand if it is running. */
 986         ssh_kill_proxy_command();
 987
 988         return exit_status;
 989 }
 990
 991 static void
 992 control_persist_detach(void)
 993 {
 994         pid_t pid;
 995         int devnull;
 996
 997         debug("%s: backgrounding master process", __func__);
 998
 999         /*
1000          * master (current process) into the background, and make the
1001          * foreground process a client of the backgrounded master.
1002          */
1003         switch ((pid = fork())) {
1004         case -1:
1005                 fatal("%s: fork: %s", __func__, strerror(errno));
1006         case 0:
1007                 /* Child: master process continues mainloop */
1008                 break;
1009         default:
1010                 /* Parent: set up mux slave to connect to backgrounded master */
1011                 debug2("%s: background process is %ld", __func__, (long)pid);
1012                 stdin_null_flag = ostdin_null_flag;
1013                 options.request_tty = orequest_tty;
1014                 tty_flag = otty_flag;
1015                 close(muxserver_sock);
1016                 muxserver_sock = -1;
1017                 options.control_master = SSHCTL_MASTER_NO;
1018                 muxclient(options.control_path);
1019                 /* muxclient() doesn't return on success. */
1020                 fatal("Failed to connect to new control master");
1021         }
1022         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1023                 error("%s: open(\"/dev/null\"): %s", __func__,
1024                     strerror(errno));
1025         } else {
1026                 if (dup2(devnull, STDIN_FILENO) == -1 ||
1027                     dup2(devnull, STDOUT_FILENO) == -1)
1028                         error("%s: dup2: %s", __func__, strerror(errno));
1029                 if (devnull > STDERR_FILENO)
1030                         close(devnull);
1031         }
1032         setproctitle("%s [mux]", options.control_path);
1033 }
1034
1035 /* Do fork() after authentication. Used by "ssh -f" */
1036 static void
1037 fork_postauth(void)
1038 {
1039         if (need_controlpersist_detach)
1040                 control_persist_detach();
1041         debug("forking to background");
1042         fork_after_authentication_flag = 0;
1043         if (daemon(1, 1) < 0)
1044                 fatal("daemon() failed: %.200s", strerror(errno));
1045 }
1046
1047 /* Callback for remote forward global requests */
1048 static void
1049 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
1050 {
1051         Forward *rfwd = (Forward *)ctxt;
1052
1053         /* XXX verbose() on failure? */
1054         debug("remote forward %s for: listen %d, connect %s:%d",
1055             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1056             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
1057         if (rfwd->listen_port == 0) {
1058                 if (type == SSH2_MSG_REQUEST_SUCCESS) {
1059                         rfwd->allocated_port = packet_get_int();
1060                         logit("Allocated port %u for remote forward to %s:%d",
1061                             rfwd->allocated_port,
1062                             rfwd->connect_host, rfwd->connect_port);
1063                         channel_update_permitted_opens(rfwd->handle,
1064                             rfwd->allocated_port);
1065                 } else {
1066                         channel_update_permitted_opens(rfwd->handle, -1);
1067                 }
1068         }
1069
1070         if (type == SSH2_MSG_REQUEST_FAILURE) {
1071                 if (options.exit_on_forward_failure)
1072                         fatal("Error: remote port forwarding failed for "
1073                             "listen port %d", rfwd->listen_port);
1074                 else
1075                         logit("Warning: remote port forwarding failed for "
1076                             "listen port %d", rfwd->listen_port);
1077         }
1078         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1079                 debug("All remote forwarding requests processed");
1080                 if (fork_after_authentication_flag)
1081                         fork_postauth();
1082         }
1083 }
1084
1085 static void
1086 client_cleanup_stdio_fwd(int id, void *arg)
1087 {
1088         debug("stdio forwarding: done");
1089         cleanup_exit(0);
1090 }
1091
1092 static void
1093 ssh_init_stdio_forwarding(void)
1094 {
1095         Channel *c;
1096         int in, out;
1097
1098         if (stdio_forward_host == NULL)
1099                 return;
1100         if (!compat20)
1101                 fatal("stdio forwarding require Protocol 2");
1102
1103         debug3("%s: %s:%d", __func__, stdio_forward_host, stdio_forward_port);
1104
1105         if ((in = dup(STDIN_FILENO)) < 0 ||
1106             (out = dup(STDOUT_FILENO)) < 0)
1107                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1108         if ((c = channel_connect_stdio_fwd(stdio_forward_host,
1109             stdio_forward_port, in, out)) == NULL)
1110                 fatal("%s: channel_connect_stdio_fwd failed", __func__);
1111         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1112 }
1113
1114 static void
1115 ssh_init_forwarding(void)
1116 {
1117         int success = 0;
1118         int i;
1119
1120         /* Initiate local TCP/IP port forwardings. */
1121         for (i = 0; i < options.num_local_forwards; i++) {
1122                 debug("Local connections to %.200s:%d forwarded to remote "
1123                     "address %.200s:%d",
1124                     (options.local_forwards[i].listen_host == NULL) ?
1125                     (options.gateway_ports ? "*" : "LOCALHOST") :
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                 success += channel_setup_local_fwd_listener(
1131                     options.local_forwards[i].listen_host,
1132                     options.local_forwards[i].listen_port,
1133                     options.local_forwards[i].connect_host,
1134                     options.local_forwards[i].connect_port,
1135                     options.gateway_ports);
1136         }
1137         if (i > 0 && success != i && options.exit_on_forward_failure)
1138                 fatal("Could not request local forwarding.");
1139         if (i > 0 && success == 0)
1140                 error("Could not request local forwarding.");
1141
1142         /* Initiate remote TCP/IP port forwardings. */
1143         for (i = 0; i < options.num_remote_forwards; i++) {
1144                 debug("Remote connections from %.200s:%d forwarded to "
1145                     "local address %.200s:%d",
1146                     (options.remote_forwards[i].listen_host == NULL) ?
1147                     "LOCALHOST" : 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);
1151                 options.remote_forwards[i].handle =
1152                     channel_request_remote_forwarding(
1153                     options.remote_forwards[i].listen_host,
1154                     options.remote_forwards[i].listen_port,
1155                     options.remote_forwards[i].connect_host,
1156                     options.remote_forwards[i].connect_port);
1157                 if (options.remote_forwards[i].handle < 0) {
1158                         if (options.exit_on_forward_failure)
1159                                 fatal("Could not request remote forwarding.");
1160                         else
1161                                 logit("Warning: Could not request remote "
1162                                     "forwarding.");
1163                 } else {
1164                         client_register_global_confirm(ssh_confirm_remote_forward,
1165                             &options.remote_forwards[i]);
1166                 }
1167         }
1168
1169         /* Initiate tunnel forwarding. */
1170         if (options.tun_open != SSH_TUNMODE_NO) {
1171                 if (client_request_tun_fwd(options.tun_open,
1172                     options.tun_local, options.tun_remote) == -1) {
1173                         if (options.exit_on_forward_failure)
1174                                 fatal("Could not request tunnel forwarding.");
1175                         else
1176                                 error("Could not request tunnel forwarding.");
1177                 }
1178         }
1179 }
1180
1181 static void
1182 check_agent_present(void)
1183 {
1184         if (options.forward_agent) {
1185                 /* Clear agent forwarding if we don't have an agent. */
1186                 if (!ssh_agent_present())
1187                         options.forward_agent = 0;
1188         }
1189 }
1190
1191 static int
1192 ssh_session(void)
1193 {
1194         int type;
1195         int interactive = 0;
1196         int have_tty = 0;
1197         struct winsize ws;
1198         char *cp;
1199         const char *display;
1200
1201         /* Enable compression if requested. */
1202         if (options.compression) {
1203                 debug("Requesting compression at level %d.",
1204                     options.compression_level);
1205
1206                 if (options.compression_level < 1 ||
1207                     options.compression_level > 9)
1208                         fatal("Compression level must be from 1 (fast) to "
1209                             "9 (slow, best).");
1210
1211                 /* Send the request. */
1212                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1213                 packet_put_int(options.compression_level);
1214                 packet_send();
1215                 packet_write_wait();
1216                 type = packet_read();
1217                 if (type == SSH_SMSG_SUCCESS)
1218                         packet_start_compression(options.compression_level);
1219                 else if (type == SSH_SMSG_FAILURE)
1220                         logit("Warning: Remote host refused compression.");
1221                 else
1222                         packet_disconnect("Protocol error waiting for "
1223                             "compression response.");
1224         }
1225         /* Allocate a pseudo tty if appropriate. */
1226         if (tty_flag) {
1227                 debug("Requesting pty.");
1228
1229                 /* Start the packet. */
1230                 packet_start(SSH_CMSG_REQUEST_PTY);
1231
1232                 /* Store TERM in the packet.  There is no limit on the
1233                    length of the string. */
1234                 cp = getenv("TERM");
1235                 if (!cp)
1236                         cp = "";
1237                 packet_put_cstring(cp);
1238
1239                 /* Store window size in the packet. */
1240                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1241                         memset(&ws, 0, sizeof(ws));
1242                 packet_put_int((u_int)ws.ws_row);
1243                 packet_put_int((u_int)ws.ws_col);
1244                 packet_put_int((u_int)ws.ws_xpixel);
1245                 packet_put_int((u_int)ws.ws_ypixel);
1246
1247                 /* Store tty modes in the packet. */
1248                 tty_make_modes(fileno(stdin), NULL);
1249
1250                 /* Send the packet, and wait for it to leave. */
1251                 packet_send();
1252                 packet_write_wait();
1253
1254                 /* Read response from the server. */
1255                 type = packet_read();
1256                 if (type == SSH_SMSG_SUCCESS) {
1257                         interactive = 1;
1258                         have_tty = 1;
1259                 } else if (type == SSH_SMSG_FAILURE)
1260                         logit("Warning: Remote host failed or refused to "
1261                             "allocate a pseudo tty.");
1262                 else
1263                         packet_disconnect("Protocol error waiting for pty "
1264                             "request response.");
1265         }
1266         /* Request X11 forwarding if enabled and DISPLAY is set. */
1267         display = getenv("DISPLAY");
1268         if (options.forward_x11 && display != NULL) {
1269                 char *proto, *data;
1270                 /* Get reasonable local authentication information. */
1271                 client_x11_get_proto(display, options.xauth_location,
1272                     options.forward_x11_trusted,
1273                     options.forward_x11_timeout,
1274                     &proto, &data);
1275                 /* Request forwarding with authentication spoofing. */
1276                 debug("Requesting X11 forwarding with authentication "
1277                     "spoofing.");
1278                 x11_request_forwarding_with_spoofing(0, display, proto,
1279                     data, 0);
1280                 /* Read response from the server. */
1281                 type = packet_read();
1282                 if (type == SSH_SMSG_SUCCESS) {
1283                         interactive = 1;
1284                 } else if (type == SSH_SMSG_FAILURE) {
1285                         logit("Warning: Remote host denied X11 forwarding.");
1286                 } else {
1287                         packet_disconnect("Protocol error waiting for X11 "
1288                             "forwarding");
1289                 }
1290         }
1291         /* Tell the packet module whether this is an interactive session. */
1292         packet_set_interactive(interactive,
1293             options.ip_qos_interactive, options.ip_qos_bulk);
1294
1295         /* Request authentication agent forwarding if appropriate. */
1296         check_agent_present();
1297
1298         if (options.forward_agent) {
1299                 debug("Requesting authentication agent forwarding.");
1300                 auth_request_forwarding();
1301
1302                 /* Read response from the server. */
1303                 type = packet_read();
1304                 packet_check_eom();
1305                 if (type != SSH_SMSG_SUCCESS)
1306                         logit("Warning: Remote host denied authentication agent forwarding.");
1307         }
1308
1309         /* Initiate port forwardings. */
1310         ssh_init_stdio_forwarding();
1311         ssh_init_forwarding();
1312
1313         /* Execute a local command */
1314         if (options.local_command != NULL &&
1315             options.permit_local_command)
1316                 ssh_local_cmd(options.local_command);
1317
1318         /*
1319          * If requested and we are not interested in replies to remote
1320          * forwarding requests, then let ssh continue in the background.
1321          */
1322         if (fork_after_authentication_flag) {
1323                 if (options.exit_on_forward_failure &&
1324                     options.num_remote_forwards > 0) {
1325                         debug("deferring postauth fork until remote forward "
1326                             "confirmation received");
1327                 } else
1328                         fork_postauth();
1329         }
1330
1331         /*
1332          * If a command was specified on the command line, execute the
1333          * command now. Otherwise request the server to start a shell.
1334          */
1335         if (buffer_len(&command) > 0) {
1336                 int len = buffer_len(&command);
1337                 if (len > 900)
1338                         len = 900;
1339                 debug("Sending command: %.*s", len,
1340                     (u_char *)buffer_ptr(&command));
1341                 packet_start(SSH_CMSG_EXEC_CMD);
1342                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1343                 packet_send();
1344                 packet_write_wait();
1345         } else {
1346                 debug("Requesting shell.");
1347                 packet_start(SSH_CMSG_EXEC_SHELL);
1348                 packet_send();
1349                 packet_write_wait();
1350         }
1351
1352         /* Enter the interactive session. */
1353         return client_loop(have_tty, tty_flag ?
1354             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1355 }
1356
1357 /* request pty/x11/agent/tcpfwd/shell for channel */
1358 static void
1359 ssh_session2_setup(int id, int success, void *arg)
1360 {
1361         extern char **environ;
1362         const char *display;
1363         int interactive = tty_flag;
1364
1365         if (!success)
1366                 return; /* No need for error message, channels code sens one */
1367
1368         display = getenv("DISPLAY");
1369         if (options.forward_x11 && display != NULL) {
1370                 char *proto, *data;
1371                 /* Get reasonable local authentication information. */
1372                 client_x11_get_proto(display, options.xauth_location,
1373                     options.forward_x11_trusted,
1374                     options.forward_x11_timeout, &proto, &data);
1375                 /* Request forwarding with authentication spoofing. */
1376                 debug("Requesting X11 forwarding with authentication "
1377                     "spoofing.");
1378                 x11_request_forwarding_with_spoofing(id, display, proto,
1379                     data, 1);
1380                 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
1381                 /* XXX exit_on_forward_failure */
1382                 interactive = 1;
1383         }
1384
1385         check_agent_present();
1386         if (options.forward_agent) {
1387                 debug("Requesting authentication agent forwarding.");
1388                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1389                 packet_send();
1390         }
1391
1392         /* Tell the packet module whether this is an interactive session. */
1393         packet_set_interactive(interactive,
1394             options.ip_qos_interactive, options.ip_qos_bulk);
1395
1396         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1397             NULL, fileno(stdin), &command, environ);
1398 }
1399
1400 /* open new channel for a session */
1401 static int
1402 ssh_session2_open(void)
1403 {
1404         Channel *c;
1405         int window, packetmax, in, out, err;
1406
1407         if (stdin_null_flag) {
1408                 in = open(_PATH_DEVNULL, O_RDONLY);
1409         } else {
1410                 in = dup(STDIN_FILENO);
1411         }
1412         out = dup(STDOUT_FILENO);
1413         err = dup(STDERR_FILENO);
1414
1415         if (in < 0 || out < 0 || err < 0)
1416                 fatal("dup() in/out/err failed");
1417
1418         /* enable nonblocking unless tty */
1419         if (!isatty(in))
1420                 set_nonblock(in);
1421         if (!isatty(out))
1422                 set_nonblock(out);
1423         if (!isatty(err))
1424                 set_nonblock(err);
1425
1426         /*
1427          * We need to check to see what to do about buffer sizes here.
1428          * - In an HPN to non-HPN connection we want to limit the window size to
1429          *   something reasonable in case the far side has the large window bug.
1430          * - In an HPN to HPN connection we want to use the max window size but
1431          *   allow the user to override it.
1432          * - Lastly if HPN is disabled then use the ssh standard window size.
1433          *
1434          * We cannot just do a getsockopt() here and set the ssh window to that
1435          * as in case of autotuning of socket buffers the window would get stuck
1436          * at the initial buffer size, generally less than 96k.  Therefore we
1437          * need to set the maximum ssh window size to the maximum HPN buffer
1438          * size unless the user has set TcpRcvBufPoll to no.  In that case we
1439          * can just set the window to the minimum of HPN buffer size and TCP
1440          * receive buffer size.
1441          */
1442         if (tty_flag)
1443                 options.hpn_buffer_size = CHAN_SES_WINDOW_DEFAULT;
1444         else
1445                 options.hpn_buffer_size = CHAN_HPN_MIN_WINDOW_DEFAULT;
1446
1447         if (datafellows & SSH_BUG_LARGEWINDOW) {
1448                 debug("HPN to Non-HPN Connection");
1449         } else if (options.tcp_rcv_buf_poll <= 0) {
1450                 sock_get_rcvbuf(&options.hpn_buffer_size, 0);
1451                 debug("HPNBufferSize set to TCP RWIN: %d",
1452                     options.hpn_buffer_size);
1453         } else if (options.tcp_rcv_buf > 0) {
1454                 sock_get_rcvbuf(&options.hpn_buffer_size,
1455                     options.tcp_rcv_buf);
1456                 debug("HPNBufferSize set to user TCPRcvBuf: %d",
1457                     options.hpn_buffer_size);
1458         }
1459         debug("Final hpn_buffer_size = %d", options.hpn_buffer_size);
1460         channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1461         window = options.hpn_buffer_size;
1462
1463         packetmax = CHAN_SES_PACKET_DEFAULT;
1464         if (tty_flag) {
1465                 window = CHAN_SES_WINDOW_DEFAULT;
1466                 window >>= 1;
1467                 packetmax >>= 1;
1468         }
1469         c = channel_new(
1470             "session", SSH_CHANNEL_OPENING, in, out, err,
1471             window, packetmax, CHAN_EXTENDED_WRITE,
1472             "client-session", /*nonblock*/0);
1473         if (!options.hpn_disabled && options.tcp_rcv_buf_poll > 0) {
1474                 c->dynamic_window = 1;
1475                 debug("Enabled Dynamic Window Scaling\n");
1476         }
1477
1478         debug3("ssh_session2_open: channel_new: %d", c->self);
1479
1480         channel_send_open(c->self);
1481         if (!no_shell_flag)
1482                 channel_register_open_confirm(c->self,
1483                     ssh_session2_setup, NULL);
1484
1485         return c->self;
1486 }
1487
1488 static int
1489 ssh_session2(void)
1490 {
1491         int id = -1;
1492
1493         /* XXX should be pre-session */
1494         if (!options.control_persist)
1495                 ssh_init_stdio_forwarding();
1496         ssh_init_forwarding();
1497
1498         /* Start listening for multiplex clients */
1499         muxserver_listen();
1500
1501         /*
1502          * If we are in control persist mode and have a working mux listen
1503          * socket, then prepare to background ourselves and have a foreground
1504          * client attach as a control slave.
1505          * NB. we must save copies of the flags that we override for
1506          * the backgrounding, since we defer attachment of the slave until
1507          * after the connection is fully established (in particular,
1508          * async rfwd replies have been received for ExitOnForwardFailure).
1509          */
1510         if (options.control_persist && muxserver_sock != -1) {
1511                 ostdin_null_flag = stdin_null_flag;
1512                 ono_shell_flag = no_shell_flag;
1513                 orequest_tty = options.request_tty;
1514                 otty_flag = tty_flag;
1515                 stdin_null_flag = 1;
1516                 no_shell_flag = 1;
1517                 tty_flag = 0;
1518                 if (!fork_after_authentication_flag)
1519                         need_controlpersist_detach = 1;
1520                 fork_after_authentication_flag = 1;
1521         }
1522         /*
1523          * ControlPersist mux listen socket setup failed, attempt the
1524          * stdio forward setup that we skipped earlier.
1525          */
1526         if (options.control_persist && muxserver_sock == -1)
1527                 ssh_init_stdio_forwarding();
1528
1529         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1530                 id = ssh_session2_open();
1531
1532         /* If we don't expect to open a new session, then disallow it */
1533         if (options.control_master == SSHCTL_MASTER_NO &&
1534             (datafellows & SSH_NEW_OPENSSH)) {
1535                 debug("Requesting no-more-sessions@openssh.com");
1536                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1537                 packet_put_cstring("no-more-sessions@openssh.com");
1538                 packet_put_char(0);
1539                 packet_send();
1540         }
1541
1542         /* Execute a local command */
1543         if (options.local_command != NULL &&
1544             options.permit_local_command)
1545                 ssh_local_cmd(options.local_command);
1546
1547         /*
1548          * If requested and we are not interested in replies to remote
1549          * forwarding requests, then let ssh continue in the background.
1550          */
1551         if (fork_after_authentication_flag) {
1552                 if (options.exit_on_forward_failure &&
1553                     options.num_remote_forwards > 0) {
1554                         debug("deferring postauth fork until remote forward "
1555                             "confirmation received");
1556                 } else
1557                         fork_postauth();
1558         }
1559
1560         if (options.use_roaming)
1561                 request_roaming();
1562
1563         return client_loop(tty_flag, tty_flag ?
1564             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1565 }
1566
1567 static void
1568 load_public_identity_files(void)
1569 {
1570         char *filename, *cp, thishost[NI_MAXHOST];
1571         char *pwdir = NULL, *pwname = NULL;
1572         int i = 0;
1573         Key *public;
1574         struct passwd *pw;
1575         u_int n_ids;
1576         char *identity_files[SSH_MAX_IDENTITY_FILES];
1577         Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1578 #ifdef ENABLE_PKCS11
1579         Key **keys;
1580         int nkeys;
1581 #endif /* PKCS11 */
1582
1583         n_ids = 0;
1584         bzero(identity_files, sizeof(identity_files));
1585         bzero(identity_keys, sizeof(identity_keys));
1586
1587 #ifdef ENABLE_PKCS11
1588         if (options.pkcs11_provider != NULL &&
1589             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1590             (pkcs11_init(!options.batch_mode) == 0) &&
1591             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1592             &keys)) > 0) {
1593                 for (i = 0; i < nkeys; i++) {
1594                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1595                                 key_free(keys[i]);
1596                                 continue;
1597                         }
1598                         identity_keys[n_ids] = keys[i];
1599                         identity_files[n_ids] =
1600                             xstrdup(options.pkcs11_provider); /* XXX */
1601                         n_ids++;
1602                 }
1603                 xfree(keys);
1604         }
1605 #endif /* ENABLE_PKCS11 */
1606         if ((pw = getpwuid(original_real_uid)) == NULL)
1607                 fatal("load_public_identity_files: getpwuid failed");
1608         pwname = xstrdup(pw->pw_name);
1609         pwdir = xstrdup(pw->pw_dir);
1610         if (gethostname(thishost, sizeof(thishost)) == -1)
1611                 fatal("load_public_identity_files: gethostname: %s",
1612                     strerror(errno));
1613         for (i = 0; i < options.num_identity_files; i++) {
1614                 if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1615                         xfree(options.identity_files[i]);
1616                         continue;
1617                 }
1618                 cp = tilde_expand_filename(options.identity_files[i],
1619                     original_real_uid);
1620                 filename = percent_expand(cp, "d", pwdir,
1621                     "u", pwname, "l", thishost, "h", host,
1622                     "r", options.user, (char *)NULL);
1623                 xfree(cp);
1624                 public = key_load_public(filename, NULL);
1625                 debug("identity file %s type %d", filename,
1626                     public ? public->type : -1);
1627                 xfree(options.identity_files[i]);
1628                 identity_files[n_ids] = filename;
1629                 identity_keys[n_ids] = public;
1630
1631                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
1632                         continue;
1633
1634                 /* Try to add the certificate variant too */
1635                 xasprintf(&cp, "%s-cert", filename);
1636                 public = key_load_public(cp, NULL);
1637                 debug("identity file %s type %d", cp,
1638                     public ? public->type : -1);
1639                 if (public == NULL) {
1640                         xfree(cp);
1641                         continue;
1642                 }
1643                 if (!key_is_cert(public)) {
1644                         debug("%s: key %s type %s is not a certificate",
1645                             __func__, cp, key_type(public));
1646                         key_free(public);
1647                         xfree(cp);
1648                         continue;
1649                 }
1650                 identity_keys[n_ids] = public;
1651                 /* point to the original path, most likely the private key */
1652                 identity_files[n_ids] = xstrdup(filename);
1653                 n_ids++;
1654         }
1655         options.num_identity_files = n_ids;
1656         memcpy(options.identity_files, identity_files, sizeof(identity_files));
1657         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
1658
1659         bzero(pwname, strlen(pwname));
1660         xfree(pwname);
1661         bzero(pwdir, strlen(pwdir));
1662         xfree(pwdir);
1663 }
1664
1665 static void
1666 main_sigchld_handler(int sig)
1667 {
1668         int save_errno = errno;
1669         pid_t pid;
1670         int status;
1671
1672         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
1673             (pid < 0 && errno == EINTR))
1674                 ;
1675
1676         signal(sig, main_sigchld_handler);
1677         errno = save_errno;
1678 }
1679