crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.373 2013/02/22 22:09:01 djm Exp $ */
   2 /* $FreeBSD$ */
   3 /*
   4  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   5  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   6  *                    All rights reserved
   7  * Ssh client program.  This program can be used to log into a remote machine.
   8  * The software supports strong authentication, encryption, and forwarding
   9  * of X11, TCP/IP, and authentication connections.
  10  *
  11  * As far as I am concerned, the code I have written for this software
  12  * can be used freely for any purpose.  Any derived versions of this
  13  * software must be clearly marked as such, and if the derived work is
  14  * incompatible with the protocol description in the RFC file, it must be
  15  * called by a name other than "ssh" or "Secure Shell".
  16  *
  17  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  18  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  19  *
  20  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  21  * in Canada (German citizen).
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the above copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  *
  32  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  33  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  34  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  35  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  36  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  37  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  38  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  39  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  40  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  41  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  42  */
  43
  44 #include "includes.h"
  45 __RCSID("$FreeBSD$");
  46
  47 #include <sys/types.h>
  48 #ifdef HAVE_SYS_STAT_H
  49 # include <sys/stat.h>
  50 #endif
  51 #include <sys/resource.h>
  52 #include <sys/ioctl.h>
  53 #include <sys/param.h>
  54 #include <sys/socket.h>
  55 #include <sys/wait.h>
  56
  57 #include <ctype.h>
  58 #include <errno.h>
  59 #include <fcntl.h>
  60 #include <netdb.h>
  61 #ifdef HAVE_PATHS_H
  62 #include <paths.h>
  63 #endif
  64 #include <pwd.h>
  65 #include <signal.h>
  66 #include <stdarg.h>
  67 #include <stddef.h>
  68 #include <stdio.h>
  69 #include <stdlib.h>
  70 #include <string.h>
  71 #include <unistd.h>
  72
  73 #include <netinet/in.h>
  74 #include <arpa/inet.h>
  75
  76 #include <openssl/evp.h>
  77 #include <openssl/err.h>
  78 #include "openbsd-compat/openssl-compat.h"
  79 #include "openbsd-compat/sys-queue.h"
  80
  81 #include "xmalloc.h"
  82 #include "ssh.h"
  83 #include "ssh1.h"
  84 #include "ssh2.h"
  85 #include "canohost.h"
  86 #include "compat.h"
  87 #include "cipher.h"
  88 #include "packet.h"
  89 #include "buffer.h"
  90 #include "channels.h"
  91 #include "key.h"
  92 #include "authfd.h"
  93 #include "authfile.h"
  94 #include "pathnames.h"
  95 #include "dispatch.h"
  96 #include "clientloop.h"
  97 #include "log.h"
  98 #include "readconf.h"
  99 #include "sshconnect.h"
 100 #include "misc.h"
 101 #include "kex.h"
 102 #include "mac.h"
 103 #include "sshpty.h"
 104 #include "match.h"
 105 #include "msg.h"
 106 #include "uidswap.h"
 107 #include "roaming.h"
 108 #include "version.h"
 109
 110 #ifdef ENABLE_PKCS11
 111 #include "ssh-pkcs11.h"
 112 #endif
 113
 114 extern char *__progname;
 115
 116 /* Saves a copy of argv for setproctitle emulation */
 117 #ifndef HAVE_SETPROCTITLE
 118 static char **saved_av;
 119 #endif
 120
 121 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 122 int debug_flag = 0;
 123
 124 /* Flag indicating whether a tty should be requested */
 125 int tty_flag = 0;
 126
 127 /* don't exec a shell */
 128 int no_shell_flag = 0;
 129
 130 /*
 131  * Flag indicating that nothing should be read from stdin.  This can be set
 132  * on the command line.
 133  */
 134 int stdin_null_flag = 0;
 135
 136 /*
 137  * Flag indicating that the current process should be backgrounded and
 138  * a new slave launched in the foreground for ControlPersist.
 139  */
 140 int need_controlpersist_detach = 0;
 141
 142 /* Copies of flags for ControlPersist foreground slave */
 143 int ostdin_null_flag, ono_shell_flag, otty_flag, orequest_tty;
 144
 145 /*
 146  * Flag indicating that ssh should fork after authentication.  This is useful
 147  * so that the passphrase can be entered manually, and then ssh goes to the
 148  * background.
 149  */
 150 int fork_after_authentication_flag = 0;
 151
 152 /* forward stdio to remote host and port */
 153 char *stdio_forward_host = NULL;
 154 int stdio_forward_port = 0;
 155
 156 /*
 157  * General data structure for command line options and options configurable
 158  * in configuration files.  See readconf.h.
 159  */
 160 Options options;
 161
 162 /* optional user configfile */
 163 char *config = NULL;
 164
 165 /*
 166  * Name of the host we are connecting to.  This is the name given on the
 167  * command line, or the HostName specified for the user-supplied name in a
 168  * configuration file.
 169  */
 170 char *host;
 171
 172 /* socket address the host resolves to */
 173 struct sockaddr_storage hostaddr;
 174
 175 /* Private host keys. */
 176 Sensitive sensitive_data;
 177
 178 /* Original real UID. */
 179 uid_t original_real_uid;
 180 uid_t original_effective_uid;
 181
 182 /* command to be executed */
 183 Buffer command;
 184
 185 /* Should we execute a command or invoke a subsystem? */
 186 int subsystem_flag = 0;
 187
 188 /* # of replies received for global requests */
 189 static int remote_forward_confirms_received = 0;
 190
 191 /* mux.c */
 192 extern int muxserver_sock;
 193 extern u_int muxclient_command;
 194
 195 /* Prints a help message to the user.  This function never returns. */
 196
 197 static void
 198 usage(void)
 199 {
 200         fprintf(stderr,
 201 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
 202 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 203 "           [-I pkcs11] [-i identity_file]\n"
 204 "           [-L [bind_address:]port:host:hostport]\n"
 205 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 206 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 207 "           [-W host:port] [-w local_tun[:remote_tun]]\n"
 208 "           [user@]hostname [command]\n"
 209         );
 210         exit(255);
 211 }
 212
 213 static int ssh_session(void);
 214 static int ssh_session2(void);
 215 static void load_public_identity_files(void);
 216 static void main_sigchld_handler(int);
 217
 218 /* from muxclient.c */
 219 void muxclient(const char *);
 220 void muxserver_listen(void);
 221
 222 /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
 223 static void
 224 tilde_expand_paths(char **paths, u_int num_paths)
 225 {
 226         u_int i;
 227         char *cp;
 228
 229         for (i = 0; i < num_paths; i++) {
 230                 cp = tilde_expand_filename(paths[i], original_real_uid);
 231                 xfree(paths[i]);
 232                 paths[i] = cp;
 233         }
 234 }
 235
 236 /*
 237  * Main program for the ssh client.
 238  */
 239 int
 240 main(int ac, char **av)
 241 {
 242         int i, r, opt, exit_status, use_syslog;
 243         char *p, *cp, *line, *argv0, buf[MAXPATHLEN], *host_arg;
 244         char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
 245         struct stat st;
 246         struct passwd *pw;
 247         int dummy, timeout_ms;
 248         extern int optind, optreset;
 249         extern char *optarg;
 250
 251         struct servent *sp;
 252         Forward fwd;
 253
 254         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 255         sanitise_stdfd();
 256
 257         __progname = ssh_get_progname(av[0]);
 258
 259 #ifndef HAVE_SETPROCTITLE
 260         /* Prepare for later setproctitle emulation */
 261         /* Save argv so it isn't clobbered by setproctitle() emulation */
 262         saved_av = xcalloc(ac + 1, sizeof(*saved_av));
 263         for (i = 0; i < ac; i++)
 264                 saved_av[i] = xstrdup(av[i]);
 265         saved_av[i] = NULL;
 266         compat_init_setproctitle(ac, av);
 267         av = saved_av;
 268 #endif
 269
 270         /*
 271          * Discard other fds that are hanging around. These can cause problem
 272          * with backgrounded ssh processes started by ControlPersist.
 273          */
 274         closefrom(STDERR_FILENO + 1);
 275
 276         /*
 277          * Save the original real uid.  It will be needed later (uid-swapping
 278          * may clobber the real uid).
 279          */
 280         original_real_uid = getuid();
 281         original_effective_uid = geteuid();
 282
 283         /*
 284          * Use uid-swapping to give up root privileges for the duration of
 285          * option processing.  We will re-instantiate the rights when we are
 286          * ready to create the privileged port, and will permanently drop
 287          * them when the port has been created (actually, when the connection
 288          * has been made, as we may need to create the port several times).
 289          */
 290         PRIV_END;
 291
 292 #ifdef HAVE_SETRLIMIT
 293         /* If we are installed setuid root be careful to not drop core. */
 294         if (original_real_uid != original_effective_uid) {
 295                 struct rlimit rlim;
 296                 rlim.rlim_cur = rlim.rlim_max = 0;
 297                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 298                         fatal("setrlimit failed: %.100s", strerror(errno));
 299         }
 300 #endif
 301         /* Get user data. */
 302         pw = getpwuid(original_real_uid);
 303         if (!pw) {
 304                 logit("You don't exist, go away!");
 305                 exit(255);
 306         }
 307         /* Take a copy of the returned structure. */
 308         pw = pwcopy(pw);
 309
 310         /*
 311          * Set our umask to something reasonable, as some files are created
 312          * with the default umask.  This will make them world-readable but
 313          * writable only by the owner, which is ok for all files for which we
 314          * don't set the modes explicitly.
 315          */
 316         umask(022);
 317
 318         /*
 319          * Initialize option structure to indicate that no values have been
 320          * set.
 321          */
 322         initialize_options(&options);
 323
 324         /* Parse command-line arguments. */
 325         host = NULL;
 326         use_syslog = 0;
 327         argv0 = av[0];
 328
 329  again:
 330         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 331             "ACD:F:I:KL:MNO:PR:S:TVw:W:XYy")) != -1) {
 332                 switch (opt) {
 333                 case '1':
 334                         options.protocol = SSH_PROTO_1;
 335                         break;
 336                 case '2':
 337                         options.protocol = SSH_PROTO_2;
 338                         break;
 339                 case '4':
 340                         options.address_family = AF_INET;
 341                         break;
 342                 case '6':
 343                         options.address_family = AF_INET6;
 344                         break;
 345                 case 'n':
 346                         stdin_null_flag = 1;
 347                         break;
 348                 case 'f':
 349                         fork_after_authentication_flag = 1;
 350                         stdin_null_flag = 1;
 351                         break;
 352                 case 'x':
 353                         options.forward_x11 = 0;
 354                         break;
 355                 case 'X':
 356                         options.forward_x11 = 1;
 357                         break;
 358                 case 'y':
 359                         use_syslog = 1;
 360                         break;
 361                 case 'Y':
 362                         options.forward_x11 = 1;
 363                         options.forward_x11_trusted = 1;
 364                         break;
 365                 case 'g':
 366                         options.gateway_ports = 1;
 367                         break;
 368                 case 'O':
 369                         if (stdio_forward_host != NULL)
 370                                 fatal("Cannot specify multiplexing "
 371                                     "command with -W");
 372                         else if (muxclient_command != 0)
 373                                 fatal("Multiplexing command already specified");
 374                         if (strcmp(optarg, "check") == 0)
 375                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 376                         else if (strcmp(optarg, "forward") == 0)
 377                                 muxclient_command = SSHMUX_COMMAND_FORWARD;
 378                         else if (strcmp(optarg, "exit") == 0)
 379                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 380                         else if (strcmp(optarg, "stop") == 0)
 381                                 muxclient_command = SSHMUX_COMMAND_STOP;
 382                         else 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, SSHCONF_USERCONF)
 602                             != 0)
 603                                 exit(255);
 604                         xfree(line);
 605                         break;
 606                 case 's':
 607                         subsystem_flag = 1;
 608                         break;
 609                 case 'S':
 610                         if (options.control_path != NULL)
 611                                 free(options.control_path);
 612                         options.control_path = xstrdup(optarg);
 613                         break;
 614                 case 'b':
 615                         options.bind_address = optarg;
 616                         break;
 617                 case 'F':
 618                         config = optarg;
 619                         break;
 620                 default:
 621                         usage();
 622                 }
 623         }
 624
 625         ac -= optind;
 626         av += optind;
 627
 628         if (ac > 0 && !host) {
 629                 if (strrchr(*av, '@')) {
 630                         p = xstrdup(*av);
 631                         cp = strrchr(p, '@');
 632                         if (cp == NULL || cp == p)
 633                                 usage();
 634                         options.user = p;
 635                         *cp = '\0';
 636                         host = ++cp;
 637                 } else
 638                         host = *av;
 639                 if (ac > 1) {
 640                         optind = optreset = 1;
 641                         goto again;
 642                 }
 643                 ac--, av++;
 644         }
 645
 646         /* Check that we got a host name. */
 647         if (!host)
 648                 usage();
 649
 650         OpenSSL_add_all_algorithms();
 651         ERR_load_crypto_strings();
 652
 653         /* Initialize the command to execute on remote host. */
 654         buffer_init(&command);
 655
 656         /*
 657          * Save the command to execute on the remote host in a buffer. There
 658          * is no limit on the length of the command, except by the maximum
 659          * packet size.  Also sets the tty flag if there is no command.
 660          */
 661         if (!ac) {
 662                 /* No command specified - execute shell on a tty. */
 663                 if (subsystem_flag) {
 664                         fprintf(stderr,
 665                             "You must specify a subsystem to invoke.\n");
 666                         usage();
 667                 }
 668         } else {
 669                 /* A command has been specified.  Store it into the buffer. */
 670                 for (i = 0; i < ac; i++) {
 671                         if (i)
 672                                 buffer_append(&command, " ", 1);
 673                         buffer_append(&command, av[i], strlen(av[i]));
 674                 }
 675         }
 676
 677         /* Cannot fork to background if no command. */
 678         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 679             !no_shell_flag)
 680                 fatal("Cannot fork into background without a command "
 681                     "to execute.");
 682
 683         /*
 684          * Initialize "log" output.  Since we are the client all output
 685          * actually goes to stderr.
 686          */
 687         log_init(argv0,
 688             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 689             SYSLOG_FACILITY_USER, !use_syslog);
 690
 691         /*
 692          * Read per-user configuration file.  Ignore the system wide config
 693          * file if the user specifies a config file on the command line.
 694          */
 695         if (config != NULL) {
 696                 if (!read_config_file(config, host, &options, SSHCONF_USERCONF))
 697                         fatal("Can't open user config file %.100s: "
 698                             "%.100s", config, strerror(errno));
 699         } else {
 700                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 701                     _PATH_SSH_USER_CONFFILE);
 702                 if (r > 0 && (size_t)r < sizeof(buf))
 703                         (void)read_config_file(buf, host, &options,
 704                              SSHCONF_CHECKPERM|SSHCONF_USERCONF);
 705
 706                 /* Read systemwide configuration file after user config. */
 707                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 708                     &options, 0);
 709         }
 710
 711         /* Fill configuration defaults. */
 712         fill_default_options(&options);
 713
 714         channel_set_af(options.address_family);
 715
 716         /* reinit */
 717         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 718
 719         if (options.request_tty == REQUEST_TTY_YES ||
 720             options.request_tty == REQUEST_TTY_FORCE)
 721                 tty_flag = 1;
 722
 723         /* Allocate a tty by default if no command specified. */
 724         if (buffer_len(&command) == 0)
 725                 tty_flag = options.request_tty != REQUEST_TTY_NO;
 726
 727         /* Force no tty */
 728         if (options.request_tty == REQUEST_TTY_NO || muxclient_command != 0)
 729                 tty_flag = 0;
 730         /* Do not allocate a tty if stdin is not a tty. */
 731         if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
 732             options.request_tty != REQUEST_TTY_FORCE) {
 733                 if (tty_flag)
 734                         logit("Pseudo-terminal will not be allocated because "
 735                             "stdin is not a terminal.");
 736                 tty_flag = 0;
 737         }
 738
 739         seed_rng();
 740
 741         if (options.user == NULL)
 742                 options.user = xstrdup(pw->pw_name);
 743
 744         /* Get default port if port has not been set. */
 745         if (options.port == 0) {
 746                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 747                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 748         }
 749
 750         /* preserve host name given on command line for %n expansion */
 751         host_arg = host;
 752         if (options.hostname != NULL) {
 753                 host = percent_expand(options.hostname,
 754                     "h", host, (char *)NULL);
 755         }
 756
 757         if (gethostname(thishost, sizeof(thishost)) == -1)
 758                 fatal("gethostname: %s", strerror(errno));
 759         strlcpy(shorthost, thishost, sizeof(shorthost));
 760         shorthost[strcspn(thishost, ".")] = '\0';
 761         snprintf(portstr, sizeof(portstr), "%d", options.port);
 762
 763         if (options.local_command != NULL) {
 764                 debug3("expanding LocalCommand: %s", options.local_command);
 765                 cp = options.local_command;
 766                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 767                     "h", host, "l", thishost, "n", host_arg, "r", options.user,
 768                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 769                     (char *)NULL);
 770                 debug3("expanded LocalCommand: %s", options.local_command);
 771                 xfree(cp);
 772         }
 773
 774         /* Find canonic host name. */
 775         if (strchr(host, '.') == 0) {
 776                 struct addrinfo hints;
 777                 struct addrinfo *ai = NULL;
 778                 int errgai;
 779                 memset(&hints, 0, sizeof(hints));
 780                 hints.ai_family = options.address_family;
 781                 hints.ai_flags = AI_CANONNAME;
 782                 hints.ai_socktype = SOCK_STREAM;
 783                 errgai = getaddrinfo(host, NULL, &hints, &ai);
 784                 if (errgai == 0) {
 785                         if (ai->ai_canonname != NULL)
 786                                 host = xstrdup(ai->ai_canonname);
 787                         freeaddrinfo(ai);
 788                 }
 789         }
 790
 791         /* force lowercase for hostkey matching */
 792         if (options.host_key_alias != NULL) {
 793                 for (p = options.host_key_alias; *p; p++)
 794                         if (isupper(*p))
 795                                 *p = (char)tolower(*p);
 796         }
 797
 798         if (options.proxy_command != NULL &&
 799             strcmp(options.proxy_command, "none") == 0) {
 800                 xfree(options.proxy_command);
 801                 options.proxy_command = NULL;
 802         }
 803         if (options.control_path != NULL &&
 804             strcmp(options.control_path, "none") == 0) {
 805                 xfree(options.control_path);
 806                 options.control_path = NULL;
 807         }
 808
 809         if (options.control_path != NULL) {
 810                 cp = tilde_expand_filename(options.control_path,
 811                     original_real_uid);
 812                 xfree(options.control_path);
 813                 options.control_path = percent_expand(cp, "h", host,
 814                     "l", thishost, "n", host_arg, "r", options.user,
 815                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 816                     (char *)NULL);
 817                 xfree(cp);
 818         }
 819         if (muxclient_command != 0 && options.control_path == NULL)
 820                 fatal("No ControlPath specified for \"-O\" command");
 821         if (options.control_path != NULL)
 822                 muxclient(options.control_path);
 823
 824         timeout_ms = options.connection_timeout * 1000;
 825
 826         /* Open a connection to the remote host. */
 827         if (ssh_connect(host, &hostaddr, options.port,
 828             options.address_family, options.connection_attempts, &timeout_ms,
 829             options.tcp_keep_alive,
 830 #ifdef HAVE_CYGWIN
 831             options.use_privileged_port,
 832 #else
 833             original_effective_uid == 0 && options.use_privileged_port,
 834 #endif
 835             options.proxy_command) != 0)
 836                 exit(255);
 837
 838         if (timeout_ms > 0)
 839                 debug3("timeout: %d ms remain after connect", timeout_ms);
 840
 841         /*
 842          * If we successfully made the connection, load the host private key
 843          * in case we will need it later for combined rsa-rhosts
 844          * authentication. This must be done before releasing extra
 845          * privileges, because the file is only readable by root.
 846          * If we cannot access the private keys, load the public keys
 847          * instead and try to execute the ssh-keysign helper instead.
 848          */
 849         sensitive_data.nkeys = 0;
 850         sensitive_data.keys = NULL;
 851         sensitive_data.external_keysign = 0;
 852         if (options.rhosts_rsa_authentication ||
 853             options.hostbased_authentication) {
 854                 sensitive_data.nkeys = 7;
 855                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 856                     sizeof(Key));
 857                 for (i = 0; i < sensitive_data.nkeys; i++)
 858                         sensitive_data.keys[i] = NULL;
 859
 860                 PRIV_START;
 861                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 862                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 863                 sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
 864                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 865 #ifdef OPENSSL_HAS_ECC
 866                 sensitive_data.keys[2] = key_load_private_cert(KEY_ECDSA,
 867                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
 868 #endif
 869                 sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
 870                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 871                 sensitive_data.keys[4] = key_load_private_type(KEY_DSA,
 872                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 873 #ifdef OPENSSL_HAS_ECC
 874                 sensitive_data.keys[5] = key_load_private_type(KEY_ECDSA,
 875                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
 876 #endif
 877                 sensitive_data.keys[6] = key_load_private_type(KEY_RSA,
 878                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 879                 PRIV_END;
 880
 881                 if (options.hostbased_authentication == 1 &&
 882                     sensitive_data.keys[0] == NULL &&
 883                     sensitive_data.keys[4] == NULL &&
 884                     sensitive_data.keys[5] == NULL &&
 885                     sensitive_data.keys[6] == NULL) {
 886                         sensitive_data.keys[1] = key_load_cert(
 887                             _PATH_HOST_DSA_KEY_FILE);
 888 #ifdef OPENSSL_HAS_ECC
 889                         sensitive_data.keys[2] = key_load_cert(
 890                             _PATH_HOST_ECDSA_KEY_FILE);
 891 #endif
 892                         sensitive_data.keys[3] = key_load_cert(
 893                             _PATH_HOST_RSA_KEY_FILE);
 894                         sensitive_data.keys[4] = key_load_public(
 895                             _PATH_HOST_DSA_KEY_FILE, NULL);
 896 #ifdef OPENSSL_HAS_ECC
 897                         sensitive_data.keys[5] = key_load_public(
 898                             _PATH_HOST_ECDSA_KEY_FILE, NULL);
 899 #endif
 900                         sensitive_data.keys[6] = key_load_public(
 901                             _PATH_HOST_RSA_KEY_FILE, NULL);
 902                         sensitive_data.external_keysign = 1;
 903                 }
 904         }
 905         /*
 906          * Get rid of any extra privileges that we may have.  We will no
 907          * longer need them.  Also, extra privileges could make it very hard
 908          * to read identity files and other non-world-readable files from the
 909          * user's home directory if it happens to be on a NFS volume where
 910          * root is mapped to nobody.
 911          */
 912         if (original_effective_uid == 0) {
 913                 PRIV_START;
 914                 permanently_set_uid(pw);
 915         }
 916
 917         /*
 918          * Now that we are back to our own permissions, create ~/.ssh
 919          * directory if it doesn't already exist.
 920          */
 921         if (config == NULL) {
 922                 r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
 923                     strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 924                 if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
 925 #ifdef WITH_SELINUX
 926                         ssh_selinux_setfscreatecon(buf);
 927 #endif
 928                         if (mkdir(buf, 0700) < 0)
 929                                 error("Could not create directory '%.200s'.",
 930                                     buf);
 931 #ifdef WITH_SELINUX
 932                         ssh_selinux_setfscreatecon(NULL);
 933 #endif
 934                 }
 935         }
 936         /* load options.identity_files */
 937         load_public_identity_files();
 938
 939         /* Expand ~ in known host file names. */
 940         tilde_expand_paths(options.system_hostfiles,
 941             options.num_system_hostfiles);
 942         tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
 943
 944         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 945         signal(SIGCHLD, main_sigchld_handler);
 946
 947         /* Log into the remote system.  Never returns if the login fails. */
 948         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 949             options.port, pw, timeout_ms);
 950
 951         if (packet_connection_is_on_socket()) {
 952                 verbose("Authenticated to %s ([%s]:%d).", host,
 953                     get_remote_ipaddr(), get_remote_port());
 954         } else {
 955                 verbose("Authenticated to %s (via proxy).", host);
 956         }
 957
 958         /* We no longer need the private host keys.  Clear them now. */
 959         if (sensitive_data.nkeys != 0) {
 960                 for (i = 0; i < sensitive_data.nkeys; i++) {
 961                         if (sensitive_data.keys[i] != NULL) {
 962                                 /* Destroys contents safely */
 963                                 debug3("clear hostkey %d", i);
 964                                 key_free(sensitive_data.keys[i]);
 965                                 sensitive_data.keys[i] = NULL;
 966                         }
 967                 }
 968                 xfree(sensitive_data.keys);
 969         }
 970         for (i = 0; i < options.num_identity_files; i++) {
 971                 if (options.identity_files[i]) {
 972                         xfree(options.identity_files[i]);
 973                         options.identity_files[i] = NULL;
 974                 }
 975                 if (options.identity_keys[i]) {
 976                         key_free(options.identity_keys[i]);
 977                         options.identity_keys[i] = NULL;
 978                 }
 979         }
 980
 981         exit_status = compat20 ? ssh_session2() : ssh_session();
 982         packet_close();
 983
 984         if (options.control_path != NULL && muxserver_sock != -1)
 985                 unlink(options.control_path);
 986
 987         /* Kill ProxyCommand if it is running. */
 988         ssh_kill_proxy_command();
 989
 990         return exit_status;
 991 }
 992
 993 static void
 994 control_persist_detach(void)
 995 {
 996         pid_t pid;
 997         int devnull;
 998
 999         debug("%s: backgrounding master process", __func__);
1000
1001         /*
1002          * master (current process) into the background, and make the
1003          * foreground process a client of the backgrounded master.
1004          */
1005         switch ((pid = fork())) {
1006         case -1:
1007                 fatal("%s: fork: %s", __func__, strerror(errno));
1008         case 0:
1009                 /* Child: master process continues mainloop */
1010                 break;
1011         default:
1012                 /* Parent: set up mux slave to connect to backgrounded master */
1013                 debug2("%s: background process is %ld", __func__, (long)pid);
1014                 stdin_null_flag = ostdin_null_flag;
1015                 options.request_tty = orequest_tty;
1016                 tty_flag = otty_flag;
1017                 close(muxserver_sock);
1018                 muxserver_sock = -1;
1019                 options.control_master = SSHCTL_MASTER_NO;
1020                 muxclient(options.control_path);
1021                 /* muxclient() doesn't return on success. */
1022                 fatal("Failed to connect to new control master");
1023         }
1024         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1025                 error("%s: open(\"/dev/null\"): %s", __func__,
1026                     strerror(errno));
1027         } else {
1028                 if (dup2(devnull, STDIN_FILENO) == -1 ||
1029                     dup2(devnull, STDOUT_FILENO) == -1)
1030                         error("%s: dup2: %s", __func__, strerror(errno));
1031                 if (devnull > STDERR_FILENO)
1032                         close(devnull);
1033         }
1034         setproctitle("%s [mux]", options.control_path);
1035 }
1036
1037 /* Do fork() after authentication. Used by "ssh -f" */
1038 static void
1039 fork_postauth(void)
1040 {
1041         if (need_controlpersist_detach)
1042                 control_persist_detach();
1043         debug("forking to background");
1044         fork_after_authentication_flag = 0;
1045         if (daemon(1, 1) < 0)
1046                 fatal("daemon() failed: %.200s", strerror(errno));
1047 }
1048
1049 /* Callback for remote forward global requests */
1050 static void
1051 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
1052 {
1053         Forward *rfwd = (Forward *)ctxt;
1054
1055         /* XXX verbose() on failure? */
1056         debug("remote forward %s for: listen %d, connect %s:%d",
1057             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1058             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
1059         if (rfwd->listen_port == 0) {
1060                 if (type == SSH2_MSG_REQUEST_SUCCESS) {
1061                         rfwd->allocated_port = packet_get_int();
1062                         logit("Allocated port %u for remote forward to %s:%d",
1063                             rfwd->allocated_port,
1064                             rfwd->connect_host, rfwd->connect_port);
1065                         channel_update_permitted_opens(rfwd->handle,
1066                             rfwd->allocated_port);
1067                 } else {
1068                         channel_update_permitted_opens(rfwd->handle, -1);
1069                 }
1070         }
1071
1072         if (type == SSH2_MSG_REQUEST_FAILURE) {
1073                 if (options.exit_on_forward_failure)
1074                         fatal("Error: remote port forwarding failed for "
1075                             "listen port %d", rfwd->listen_port);
1076                 else
1077                         logit("Warning: remote port forwarding failed for "
1078                             "listen port %d", rfwd->listen_port);
1079         }
1080         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1081                 debug("All remote forwarding requests processed");
1082                 if (fork_after_authentication_flag)
1083                         fork_postauth();
1084         }
1085 }
1086
1087 static void
1088 client_cleanup_stdio_fwd(int id, void *arg)
1089 {
1090         debug("stdio forwarding: done");
1091         cleanup_exit(0);
1092 }
1093
1094 static void
1095 ssh_init_stdio_forwarding(void)
1096 {
1097         Channel *c;
1098         int in, out;
1099
1100         if (stdio_forward_host == NULL)
1101                 return;
1102         if (!compat20)
1103                 fatal("stdio forwarding require Protocol 2");
1104
1105         debug3("%s: %s:%d", __func__, stdio_forward_host, stdio_forward_port);
1106
1107         if ((in = dup(STDIN_FILENO)) < 0 ||
1108             (out = dup(STDOUT_FILENO)) < 0)
1109                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1110         if ((c = channel_connect_stdio_fwd(stdio_forward_host,
1111             stdio_forward_port, in, out)) == NULL)
1112                 fatal("%s: channel_connect_stdio_fwd failed", __func__);
1113         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1114 }
1115
1116 static void
1117 ssh_init_forwarding(void)
1118 {
1119         int success = 0;
1120         int i;
1121
1122         /* Initiate local TCP/IP port forwardings. */
1123         for (i = 0; i < options.num_local_forwards; i++) {
1124                 debug("Local connections to %.200s:%d forwarded to remote "
1125                     "address %.200s:%d",
1126                     (options.local_forwards[i].listen_host == NULL) ?
1127                     (options.gateway_ports ? "*" : "LOCALHOST") :
1128                     options.local_forwards[i].listen_host,
1129                     options.local_forwards[i].listen_port,
1130                     options.local_forwards[i].connect_host,
1131                     options.local_forwards[i].connect_port);
1132                 success += channel_setup_local_fwd_listener(
1133                     options.local_forwards[i].listen_host,
1134                     options.local_forwards[i].listen_port,
1135                     options.local_forwards[i].connect_host,
1136                     options.local_forwards[i].connect_port,
1137                     options.gateway_ports);
1138         }
1139         if (i > 0 && success != i && options.exit_on_forward_failure)
1140                 fatal("Could not request local forwarding.");
1141         if (i > 0 && success == 0)
1142                 error("Could not request local forwarding.");
1143
1144         /* Initiate remote TCP/IP port forwardings. */
1145         for (i = 0; i < options.num_remote_forwards; i++) {
1146                 debug("Remote connections from %.200s:%d forwarded to "
1147                     "local address %.200s:%d",
1148                     (options.remote_forwards[i].listen_host == NULL) ?
1149                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1150                     options.remote_forwards[i].listen_port,
1151                     options.remote_forwards[i].connect_host,
1152                     options.remote_forwards[i].connect_port);
1153                 options.remote_forwards[i].handle =
1154                     channel_request_remote_forwarding(
1155                     options.remote_forwards[i].listen_host,
1156                     options.remote_forwards[i].listen_port,
1157                     options.remote_forwards[i].connect_host,
1158                     options.remote_forwards[i].connect_port);
1159                 if (options.remote_forwards[i].handle < 0) {
1160                         if (options.exit_on_forward_failure)
1161                                 fatal("Could not request remote forwarding.");
1162                         else
1163                                 logit("Warning: Could not request remote "
1164                                     "forwarding.");
1165                 } else {
1166                         client_register_global_confirm(ssh_confirm_remote_forward,
1167                             &options.remote_forwards[i]);
1168                 }
1169         }
1170
1171         /* Initiate tunnel forwarding. */
1172         if (options.tun_open != SSH_TUNMODE_NO) {
1173                 if (client_request_tun_fwd(options.tun_open,
1174                     options.tun_local, options.tun_remote) == -1) {
1175                         if (options.exit_on_forward_failure)
1176                                 fatal("Could not request tunnel forwarding.");
1177                         else
1178                                 error("Could not request tunnel forwarding.");
1179                 }
1180         }
1181 }
1182
1183 static void
1184 check_agent_present(void)
1185 {
1186         if (options.forward_agent) {
1187                 /* Clear agent forwarding if we don't have an agent. */
1188                 if (!ssh_agent_present())
1189                         options.forward_agent = 0;
1190         }
1191 }
1192
1193 static int
1194 ssh_session(void)
1195 {
1196         int type;
1197         int interactive = 0;
1198         int have_tty = 0;
1199         struct winsize ws;
1200         char *cp;
1201         const char *display;
1202
1203         /* Enable compression if requested. */
1204         if (options.compression) {
1205                 debug("Requesting compression at level %d.",
1206                     options.compression_level);
1207
1208                 if (options.compression_level < 1 ||
1209                     options.compression_level > 9)
1210                         fatal("Compression level must be from 1 (fast) to "
1211                             "9 (slow, best).");
1212
1213                 /* Send the request. */
1214                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1215                 packet_put_int(options.compression_level);
1216                 packet_send();
1217                 packet_write_wait();
1218                 type = packet_read();
1219                 if (type == SSH_SMSG_SUCCESS)
1220                         packet_start_compression(options.compression_level);
1221                 else if (type == SSH_SMSG_FAILURE)
1222                         logit("Warning: Remote host refused compression.");
1223                 else
1224                         packet_disconnect("Protocol error waiting for "
1225                             "compression response.");
1226         }
1227         /* Allocate a pseudo tty if appropriate. */
1228         if (tty_flag) {
1229                 debug("Requesting pty.");
1230
1231                 /* Start the packet. */
1232                 packet_start(SSH_CMSG_REQUEST_PTY);
1233
1234                 /* Store TERM in the packet.  There is no limit on the
1235                    length of the string. */
1236                 cp = getenv("TERM");
1237                 if (!cp)
1238                         cp = "";
1239                 packet_put_cstring(cp);
1240
1241                 /* Store window size in the packet. */
1242                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1243                         memset(&ws, 0, sizeof(ws));
1244                 packet_put_int((u_int)ws.ws_row);
1245                 packet_put_int((u_int)ws.ws_col);
1246                 packet_put_int((u_int)ws.ws_xpixel);
1247                 packet_put_int((u_int)ws.ws_ypixel);
1248
1249                 /* Store tty modes in the packet. */
1250                 tty_make_modes(fileno(stdin), NULL);
1251
1252                 /* Send the packet, and wait for it to leave. */
1253                 packet_send();
1254                 packet_write_wait();
1255
1256                 /* Read response from the server. */
1257                 type = packet_read();
1258                 if (type == SSH_SMSG_SUCCESS) {
1259                         interactive = 1;
1260                         have_tty = 1;
1261                 } else if (type == SSH_SMSG_FAILURE)
1262                         logit("Warning: Remote host failed or refused to "
1263                             "allocate a pseudo tty.");
1264                 else
1265                         packet_disconnect("Protocol error waiting for pty "
1266                             "request response.");
1267         }
1268         /* Request X11 forwarding if enabled and DISPLAY is set. */
1269         display = getenv("DISPLAY");
1270         if (options.forward_x11 && display != NULL) {
1271                 char *proto, *data;
1272                 /* Get reasonable local authentication information. */
1273                 client_x11_get_proto(display, options.xauth_location,
1274                     options.forward_x11_trusted,
1275                     options.forward_x11_timeout,
1276                     &proto, &data);
1277                 /* Request forwarding with authentication spoofing. */
1278                 debug("Requesting X11 forwarding with authentication "
1279                     "spoofing.");
1280                 x11_request_forwarding_with_spoofing(0, display, proto,
1281                     data, 0);
1282                 /* Read response from the server. */
1283                 type = packet_read();
1284                 if (type == SSH_SMSG_SUCCESS) {
1285                         interactive = 1;
1286                 } else if (type == SSH_SMSG_FAILURE) {
1287                         logit("Warning: Remote host denied X11 forwarding.");
1288                 } else {
1289                         packet_disconnect("Protocol error waiting for X11 "
1290                             "forwarding");
1291                 }
1292         }
1293         /* Tell the packet module whether this is an interactive session. */
1294         packet_set_interactive(interactive,
1295             options.ip_qos_interactive, options.ip_qos_bulk);
1296
1297         /* Request authentication agent forwarding if appropriate. */
1298         check_agent_present();
1299
1300         if (options.forward_agent) {
1301                 debug("Requesting authentication agent forwarding.");
1302                 auth_request_forwarding();
1303
1304                 /* Read response from the server. */
1305                 type = packet_read();
1306                 packet_check_eom();
1307                 if (type != SSH_SMSG_SUCCESS)
1308                         logit("Warning: Remote host denied authentication agent forwarding.");
1309         }
1310
1311         /* Initiate port forwardings. */
1312         ssh_init_stdio_forwarding();
1313         ssh_init_forwarding();
1314
1315         /* Execute a local command */
1316         if (options.local_command != NULL &&
1317             options.permit_local_command)
1318                 ssh_local_cmd(options.local_command);
1319
1320         /*
1321          * If requested and we are not interested in replies to remote
1322          * forwarding requests, then let ssh continue in the background.
1323          */
1324         if (fork_after_authentication_flag) {
1325                 if (options.exit_on_forward_failure &&
1326                     options.num_remote_forwards > 0) {
1327                         debug("deferring postauth fork until remote forward "
1328                             "confirmation received");
1329                 } else
1330                         fork_postauth();
1331         }
1332
1333         /*
1334          * If a command was specified on the command line, execute the
1335          * command now. Otherwise request the server to start a shell.
1336          */
1337         if (buffer_len(&command) > 0) {
1338                 int len = buffer_len(&command);
1339                 if (len > 900)
1340                         len = 900;
1341                 debug("Sending command: %.*s", len,
1342                     (u_char *)buffer_ptr(&command));
1343                 packet_start(SSH_CMSG_EXEC_CMD);
1344                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1345                 packet_send();
1346                 packet_write_wait();
1347         } else {
1348                 debug("Requesting shell.");
1349                 packet_start(SSH_CMSG_EXEC_SHELL);
1350                 packet_send();
1351                 packet_write_wait();
1352         }
1353
1354         /* Enter the interactive session. */
1355         return client_loop(have_tty, tty_flag ?
1356             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1357 }
1358
1359 /* request pty/x11/agent/tcpfwd/shell for channel */
1360 static void
1361 ssh_session2_setup(int id, int success, void *arg)
1362 {
1363         extern char **environ;
1364         const char *display;
1365         int interactive = tty_flag;
1366
1367         if (!success)
1368                 return; /* No need for error message, channels code sens one */
1369
1370         display = getenv("DISPLAY");
1371         if (options.forward_x11 && display != NULL) {
1372                 char *proto, *data;
1373                 /* Get reasonable local authentication information. */
1374                 client_x11_get_proto(display, options.xauth_location,
1375                     options.forward_x11_trusted,
1376                     options.forward_x11_timeout, &proto, &data);
1377                 /* Request forwarding with authentication spoofing. */
1378                 debug("Requesting X11 forwarding with authentication "
1379                     "spoofing.");
1380                 x11_request_forwarding_with_spoofing(id, display, proto,
1381                     data, 1);
1382                 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
1383                 /* XXX exit_on_forward_failure */
1384                 interactive = 1;
1385         }
1386
1387         check_agent_present();
1388         if (options.forward_agent) {
1389                 debug("Requesting authentication agent forwarding.");
1390                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1391                 packet_send();
1392         }
1393
1394         /* Tell the packet module whether this is an interactive session. */
1395         packet_set_interactive(interactive,
1396             options.ip_qos_interactive, options.ip_qos_bulk);
1397
1398         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1399             NULL, fileno(stdin), &command, environ);
1400 }
1401
1402 /* open new channel for a session */
1403 static int
1404 ssh_session2_open(void)
1405 {
1406         Channel *c;
1407         int window, packetmax, in, out, err;
1408
1409         if (stdin_null_flag) {
1410                 in = open(_PATH_DEVNULL, O_RDONLY);
1411         } else {
1412                 in = dup(STDIN_FILENO);
1413         }
1414         out = dup(STDOUT_FILENO);
1415         err = dup(STDERR_FILENO);
1416
1417         if (in < 0 || out < 0 || err < 0)
1418                 fatal("dup() in/out/err failed");
1419
1420         /* enable nonblocking unless tty */
1421         if (!isatty(in))
1422                 set_nonblock(in);
1423         if (!isatty(out))
1424                 set_nonblock(out);
1425         if (!isatty(err))
1426                 set_nonblock(err);
1427
1428         /*
1429          * We need to check to see what to do about buffer sizes here.
1430          * - In an HPN to non-HPN connection we want to limit the window size to
1431          *   something reasonable in case the far side has the large window bug.
1432          * - In an HPN to HPN connection we want to use the max window size but
1433          *   allow the user to override it.
1434          * - Lastly if HPN is disabled then use the ssh standard window size.
1435          *
1436          * We cannot just do a getsockopt() here and set the ssh window to that
1437          * as in case of autotuning of socket buffers the window would get stuck
1438          * at the initial buffer size, generally less than 96k.  Therefore we
1439          * need to set the maximum ssh window size to the maximum HPN buffer
1440          * size unless the user has set TcpRcvBufPoll to no.  In that case we
1441          * can just set the window to the minimum of HPN buffer size and TCP
1442          * receive buffer size.
1443          */
1444         if (tty_flag)
1445                 options.hpn_buffer_size = CHAN_SES_WINDOW_DEFAULT;
1446         else
1447                 options.hpn_buffer_size = CHAN_HPN_MIN_WINDOW_DEFAULT;
1448
1449         if (datafellows & SSH_BUG_LARGEWINDOW) {
1450                 debug("HPN to Non-HPN Connection");
1451         } else if (options.tcp_rcv_buf_poll <= 0) {
1452                 sock_get_rcvbuf(&options.hpn_buffer_size, 0);
1453                 debug("HPNBufferSize set to TCP RWIN: %d",
1454                     options.hpn_buffer_size);
1455         } else if (options.tcp_rcv_buf > 0) {
1456                 sock_get_rcvbuf(&options.hpn_buffer_size,
1457                     options.tcp_rcv_buf);
1458                 debug("HPNBufferSize set to user TCPRcvBuf: %d",
1459                     options.hpn_buffer_size);
1460         }
1461         debug("Final hpn_buffer_size = %d", options.hpn_buffer_size);
1462         channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1463         window = options.hpn_buffer_size;
1464
1465         packetmax = CHAN_SES_PACKET_DEFAULT;
1466         if (tty_flag) {
1467                 window = CHAN_SES_WINDOW_DEFAULT;
1468                 window >>= 1;
1469                 packetmax >>= 1;
1470         }
1471         c = channel_new(
1472             "session", SSH_CHANNEL_OPENING, in, out, err,
1473             window, packetmax, CHAN_EXTENDED_WRITE,
1474             "client-session", /*nonblock*/0);
1475         if (!options.hpn_disabled && options.tcp_rcv_buf_poll > 0) {
1476                 c->dynamic_window = 1;
1477                 debug("Enabled Dynamic Window Scaling\n");
1478         }
1479
1480         debug3("ssh_session2_open: channel_new: %d", c->self);
1481
1482         channel_send_open(c->self);
1483         if (!no_shell_flag)
1484                 channel_register_open_confirm(c->self,
1485                     ssh_session2_setup, NULL);
1486
1487         return c->self;
1488 }
1489
1490 static int
1491 ssh_session2(void)
1492 {
1493         int id = -1;
1494
1495         /* XXX should be pre-session */
1496         if (!options.control_persist)
1497                 ssh_init_stdio_forwarding();
1498         ssh_init_forwarding();
1499
1500         /* Start listening for multiplex clients */
1501         muxserver_listen();
1502
1503         /*
1504          * If we are in control persist mode and have a working mux listen
1505          * socket, then prepare to background ourselves and have a foreground
1506          * client attach as a control slave.
1507          * NB. we must save copies of the flags that we override for
1508          * the backgrounding, since we defer attachment of the slave until
1509          * after the connection is fully established (in particular,
1510          * async rfwd replies have been received for ExitOnForwardFailure).
1511          */
1512         if (options.control_persist && muxserver_sock != -1) {
1513                 ostdin_null_flag = stdin_null_flag;
1514                 ono_shell_flag = no_shell_flag;
1515                 orequest_tty = options.request_tty;
1516                 otty_flag = tty_flag;
1517                 stdin_null_flag = 1;
1518                 no_shell_flag = 1;
1519                 tty_flag = 0;
1520                 if (!fork_after_authentication_flag)
1521                         need_controlpersist_detach = 1;
1522                 fork_after_authentication_flag = 1;
1523         }
1524         /*
1525          * ControlPersist mux listen socket setup failed, attempt the
1526          * stdio forward setup that we skipped earlier.
1527          */
1528         if (options.control_persist && muxserver_sock == -1)
1529                 ssh_init_stdio_forwarding();
1530
1531         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1532                 id = ssh_session2_open();
1533
1534         /* If we don't expect to open a new session, then disallow it */
1535         if (options.control_master == SSHCTL_MASTER_NO &&
1536             (datafellows & SSH_NEW_OPENSSH)) {
1537                 debug("Requesting no-more-sessions@openssh.com");
1538                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1539                 packet_put_cstring("no-more-sessions@openssh.com");
1540                 packet_put_char(0);
1541                 packet_send();
1542         }
1543
1544         /* Execute a local command */
1545         if (options.local_command != NULL &&
1546             options.permit_local_command)
1547                 ssh_local_cmd(options.local_command);
1548
1549         /*
1550          * If requested and we are not interested in replies to remote
1551          * forwarding requests, then let ssh continue in the background.
1552          */
1553         if (fork_after_authentication_flag) {
1554                 if (options.exit_on_forward_failure &&
1555                     options.num_remote_forwards > 0) {
1556                         debug("deferring postauth fork until remote forward "
1557                             "confirmation received");
1558                 } else
1559                         fork_postauth();
1560         }
1561
1562         if (options.use_roaming)
1563                 request_roaming();
1564
1565         return client_loop(tty_flag, tty_flag ?
1566             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1567 }
1568
1569 static void
1570 load_public_identity_files(void)
1571 {
1572         char *filename, *cp, thishost[NI_MAXHOST];
1573         char *pwdir = NULL, *pwname = NULL;
1574         int i = 0;
1575         Key *public;
1576         struct passwd *pw;
1577         u_int n_ids;
1578         char *identity_files[SSH_MAX_IDENTITY_FILES];
1579         Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1580 #ifdef ENABLE_PKCS11
1581         Key **keys;
1582         int nkeys;
1583 #endif /* PKCS11 */
1584
1585         n_ids = 0;
1586         bzero(identity_files, sizeof(identity_files));
1587         bzero(identity_keys, sizeof(identity_keys));
1588
1589 #ifdef ENABLE_PKCS11
1590         if (options.pkcs11_provider != NULL &&
1591             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1592             (pkcs11_init(!options.batch_mode) == 0) &&
1593             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1594             &keys)) > 0) {
1595                 for (i = 0; i < nkeys; i++) {
1596                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1597                                 key_free(keys[i]);
1598                                 continue;
1599                         }
1600                         identity_keys[n_ids] = keys[i];
1601                         identity_files[n_ids] =
1602                             xstrdup(options.pkcs11_provider); /* XXX */
1603                         n_ids++;
1604                 }
1605                 xfree(keys);
1606         }
1607 #endif /* ENABLE_PKCS11 */
1608         if ((pw = getpwuid(original_real_uid)) == NULL)
1609                 fatal("load_public_identity_files: getpwuid failed");
1610         pwname = xstrdup(pw->pw_name);
1611         pwdir = xstrdup(pw->pw_dir);
1612         if (gethostname(thishost, sizeof(thishost)) == -1)
1613                 fatal("load_public_identity_files: gethostname: %s",
1614                     strerror(errno));
1615         for (i = 0; i < options.num_identity_files; i++) {
1616                 if (n_ids >= SSH_MAX_IDENTITY_FILES ||
1617                     strcasecmp(options.identity_files[i], "none") == 0) {
1618                         xfree(options.identity_files[i]);
1619                         continue;
1620                 }
1621                 cp = tilde_expand_filename(options.identity_files[i],
1622                     original_real_uid);
1623                 filename = percent_expand(cp, "d", pwdir,
1624                     "u", pwname, "l", thishost, "h", host,
1625                     "r", options.user, (char *)NULL);
1626                 xfree(cp);
1627                 public = key_load_public(filename, NULL);
1628                 debug("identity file %s type %d", filename,
1629                     public ? public->type : -1);
1630                 xfree(options.identity_files[i]);
1631                 identity_files[n_ids] = filename;
1632                 identity_keys[n_ids] = public;
1633
1634                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
1635                         continue;
1636
1637                 /* Try to add the certificate variant too */
1638                 xasprintf(&cp, "%s-cert", filename);
1639                 public = key_load_public(cp, NULL);
1640                 debug("identity file %s type %d", cp,
1641                     public ? public->type : -1);
1642                 if (public == NULL) {
1643                         xfree(cp);
1644                         continue;
1645                 }
1646                 if (!key_is_cert(public)) {
1647                         debug("%s: key %s type %s is not a certificate",
1648                             __func__, cp, key_type(public));
1649                         key_free(public);
1650                         xfree(cp);
1651                         continue;
1652                 }
1653                 identity_keys[n_ids] = public;
1654                 /* point to the original path, most likely the private key */
1655                 identity_files[n_ids] = xstrdup(filename);
1656                 n_ids++;
1657         }
1658         options.num_identity_files = n_ids;
1659         memcpy(options.identity_files, identity_files, sizeof(identity_files));
1660         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
1661
1662         bzero(pwname, strlen(pwname));
1663         xfree(pwname);
1664         bzero(pwdir, strlen(pwdir));
1665         xfree(pwdir);
1666 }
1667
1668 static void
1669 main_sigchld_handler(int sig)
1670 {
1671         int save_errno = errno;
1672         pid_t pid;
1673         int status;
1674
1675         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
1676             (pid < 0 && errno == EINTR))
1677                 ;
1678
1679         signal(sig, main_sigchld_handler);
1680         errno = save_errno;
1681 }
1682