crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.346 2010/08/12 21:49:44 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * Ssh client program.  This program can be used to log into a remote machine.
   7  * The software supports strong authentication, encryption, and forwarding
   8  * of X11, TCP/IP, and authentication connections.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  17  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  18  *
  19  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  20  * in Canada (German citizen).
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the above copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  *
  31  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  32  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  34  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  35  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  36  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  37  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  38  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  39  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  40  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  41  */
  42
  43 #include "includes.h"
  44
  45 #include <sys/types.h>
  46 #ifdef HAVE_SYS_STAT_H
  47 # include <sys/stat.h>
  48 #endif
  49 #include <sys/resource.h>
  50 #include <sys/ioctl.h>
  51 #include <sys/param.h>
  52 #include <sys/socket.h>
  53
  54 #include <ctype.h>
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #include <netdb.h>
  58 #ifdef HAVE_PATHS_H
  59 #include <paths.h>
  60 #endif
  61 #include <pwd.h>
  62 #include <signal.h>
  63 #include <stdarg.h>
  64 #include <stddef.h>
  65 #include <stdio.h>
  66 #include <stdlib.h>
  67 #include <string.h>
  68 #include <unistd.h>
  69
  70 #include <netinet/in.h>
  71 #include <arpa/inet.h>
  72
  73 #include <openssl/evp.h>
  74 #include <openssl/err.h>
  75 #include "openbsd-compat/openssl-compat.h"
  76 #include "openbsd-compat/sys-queue.h"
  77
  78 #include "xmalloc.h"
  79 #include "ssh.h"
  80 #include "ssh1.h"
  81 #include "ssh2.h"
  82 #include "canohost.h"
  83 #include "compat.h"
  84 #include "cipher.h"
  85 #include "packet.h"
  86 #include "buffer.h"
  87 #include "channels.h"
  88 #include "key.h"
  89 #include "authfd.h"
  90 #include "authfile.h"
  91 #include "pathnames.h"
  92 #include "dispatch.h"
  93 #include "clientloop.h"
  94 #include "log.h"
  95 #include "readconf.h"
  96 #include "sshconnect.h"
  97 #include "misc.h"
  98 #include "kex.h"
  99 #include "mac.h"
 100 #include "sshpty.h"
 101 #include "match.h"
 102 #include "msg.h"
 103 #include "uidswap.h"
 104 #include "roaming.h"
 105 #include "version.h"
 106
 107 #ifdef ENABLE_PKCS11
 108 #include "ssh-pkcs11.h"
 109 #endif
 110
 111 extern char *__progname;
 112
 113 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 114 int debug_flag = 0;
 115
 116 /* Flag indicating whether a tty should be allocated */
 117 int tty_flag = 0;
 118 int no_tty_flag = 0;
 119 int force_tty_flag = 0;
 120
 121 /* don't exec a shell */
 122 int no_shell_flag = 0;
 123
 124 /*
 125  * Flag indicating that nothing should be read from stdin.  This can be set
 126  * on the command line.
 127  */
 128 int stdin_null_flag = 0;
 129
 130 /*
 131  * Flag indicating that the current process should be backgrounded and
 132  * a new slave launched in the foreground for ControlPersist.
 133  */
 134 int need_controlpersist_detach = 0;
 135
 136 /* Copies of flags for ControlPersist foreground slave */
 137 int ostdin_null_flag, ono_shell_flag, ono_tty_flag, otty_flag;
 138
 139 /*
 140  * Flag indicating that ssh should fork after authentication.  This is useful
 141  * so that the passphrase can be entered manually, and then ssh goes to the
 142  * background.
 143  */
 144 int fork_after_authentication_flag = 0;
 145
 146 /* forward stdio to remote host and port */
 147 char *stdio_forward_host = NULL;
 148 int stdio_forward_port = 0;
 149
 150 /*
 151  * General data structure for command line options and options configurable
 152  * in configuration files.  See readconf.h.
 153  */
 154 Options options;
 155
 156 /* optional user configfile */
 157 char *config = NULL;
 158
 159 /*
 160  * Name of the host we are connecting to.  This is the name given on the
 161  * command line, or the HostName specified for the user-supplied name in a
 162  * configuration file.
 163  */
 164 char *host;
 165
 166 /* socket address the host resolves to */
 167 struct sockaddr_storage hostaddr;
 168
 169 /* Private host keys. */
 170 Sensitive sensitive_data;
 171
 172 /* Original real UID. */
 173 uid_t original_real_uid;
 174 uid_t original_effective_uid;
 175
 176 /* command to be executed */
 177 Buffer command;
 178
 179 /* Should we execute a command or invoke a subsystem? */
 180 int subsystem_flag = 0;
 181
 182 /* # of replies received for global requests */
 183 static int remote_forward_confirms_received = 0;
 184
 185 /* pid of proxycommand child process */
 186 pid_t proxy_command_pid = 0;
 187
 188 /* mux.c */
 189 extern int muxserver_sock;
 190 extern u_int muxclient_command;
 191
 192 /* Prints a help message to the user.  This function never returns. */
 193
 194 static void
 195 usage(void)
 196 {
 197         fprintf(stderr,
 198 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
 199 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 200 "           [-I pkcs11] [-i identity_file]\n"
 201 "           [-L [bind_address:]port:host:hostport]\n"
 202 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 203 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 204 "           [-W host:port] [-w local_tun[:remote_tun]]\n"
 205 "           [user@]hostname [command]\n"
 206         );
 207         exit(255);
 208 }
 209
 210 static int ssh_session(void);
 211 static int ssh_session2(void);
 212 static void load_public_identity_files(void);
 213
 214 /* from muxclient.c */
 215 void muxclient(const char *);
 216 void muxserver_listen(void);
 217
 218 /*
 219  * Main program for the ssh client.
 220  */
 221 int
 222 main(int ac, char **av)
 223 {
 224         int i, r, opt, exit_status, use_syslog;
 225         char *p, *cp, *line, *argv0, buf[MAXPATHLEN];
 226         struct stat st;
 227         struct passwd *pw;
 228         int dummy, timeout_ms;
 229         extern int optind, optreset;
 230         extern char *optarg;
 231         struct servent *sp;
 232         Forward fwd;
 233
 234         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 235         sanitise_stdfd();
 236
 237         __progname = ssh_get_progname(av[0]);
 238         init_rng();
 239
 240         /*
 241          * Discard other fds that are hanging around. These can cause problem
 242          * with backgrounded ssh processes started by ControlPersist.
 243          */
 244         closefrom(STDERR_FILENO + 1);
 245
 246         /*
 247          * Save the original real uid.  It will be needed later (uid-swapping
 248          * may clobber the real uid).
 249          */
 250         original_real_uid = getuid();
 251         original_effective_uid = geteuid();
 252
 253         /*
 254          * Use uid-swapping to give up root privileges for the duration of
 255          * option processing.  We will re-instantiate the rights when we are
 256          * ready to create the privileged port, and will permanently drop
 257          * them when the port has been created (actually, when the connection
 258          * has been made, as we may need to create the port several times).
 259          */
 260         PRIV_END;
 261
 262 #ifdef HAVE_SETRLIMIT
 263         /* If we are installed setuid root be careful to not drop core. */
 264         if (original_real_uid != original_effective_uid) {
 265                 struct rlimit rlim;
 266                 rlim.rlim_cur = rlim.rlim_max = 0;
 267                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 268                         fatal("setrlimit failed: %.100s", strerror(errno));
 269         }
 270 #endif
 271         /* Get user data. */
 272         pw = getpwuid(original_real_uid);
 273         if (!pw) {
 274                 logit("You don't exist, go away!");
 275                 exit(255);
 276         }
 277         /* Take a copy of the returned structure. */
 278         pw = pwcopy(pw);
 279
 280         /*
 281          * Set our umask to something reasonable, as some files are created
 282          * with the default umask.  This will make them world-readable but
 283          * writable only by the owner, which is ok for all files for which we
 284          * don't set the modes explicitly.
 285          */
 286         umask(022);
 287
 288         /*
 289          * Initialize option structure to indicate that no values have been
 290          * set.
 291          */
 292         initialize_options(&options);
 293
 294         /* Parse command-line arguments. */
 295         host = NULL;
 296         use_syslog = 0;
 297         argv0 = av[0];
 298
 299  again:
 300         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 301             "ACD:F:I:KL:MNO:PR:S:TVw:W:XYy")) != -1) {
 302                 switch (opt) {
 303                 case '1':
 304                         options.protocol = SSH_PROTO_1;
 305                         break;
 306                 case '2':
 307                         options.protocol = SSH_PROTO_2;
 308                         break;
 309                 case '4':
 310                         options.address_family = AF_INET;
 311                         break;
 312                 case '6':
 313                         options.address_family = AF_INET6;
 314                         break;
 315                 case 'n':
 316                         stdin_null_flag = 1;
 317                         break;
 318                 case 'f':
 319                         fork_after_authentication_flag = 1;
 320                         stdin_null_flag = 1;
 321                         break;
 322                 case 'x':
 323                         options.forward_x11 = 0;
 324                         break;
 325                 case 'X':
 326                         options.forward_x11 = 1;
 327                         break;
 328                 case 'y':
 329                         use_syslog = 1;
 330                         break;
 331                 case 'Y':
 332                         options.forward_x11 = 1;
 333                         options.forward_x11_trusted = 1;
 334                         break;
 335                 case 'g':
 336                         options.gateway_ports = 1;
 337                         break;
 338                 case 'O':
 339                         if (stdio_forward_host != NULL)
 340                                 fatal("Cannot specify multiplexing "
 341                                     "command with -W");
 342                         else if (muxclient_command != 0)
 343                                 fatal("Multiplexing command already specified");
 344                         if (strcmp(optarg, "check") == 0)
 345                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 346                         else if (strcmp(optarg, "forward") == 0)
 347                                 muxclient_command = SSHMUX_COMMAND_FORWARD;
 348                         else if (strcmp(optarg, "exit") == 0)
 349                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 350                         else
 351                                 fatal("Invalid multiplex command.");
 352                         break;
 353                 case 'P':       /* deprecated */
 354                         options.use_privileged_port = 0;
 355                         break;
 356                 case 'a':
 357                         options.forward_agent = 0;
 358                         break;
 359                 case 'A':
 360                         options.forward_agent = 1;
 361                         break;
 362                 case 'k':
 363                         options.gss_deleg_creds = 0;
 364                         break;
 365                 case 'K':
 366                         options.gss_authentication = 1;
 367                         options.gss_deleg_creds = 1;
 368                         break;
 369                 case 'i':
 370                         if (stat(optarg, &st) < 0) {
 371                                 fprintf(stderr, "Warning: Identity file %s "
 372                                     "not accessible: %s.\n", optarg,
 373                                     strerror(errno));
 374                                 break;
 375                         }
 376                         if (options.num_identity_files >=
 377                             SSH_MAX_IDENTITY_FILES)
 378                                 fatal("Too many identity files specified "
 379                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 380                         options.identity_files[options.num_identity_files++] =
 381                             xstrdup(optarg);
 382                         break;
 383                 case 'I':
 384 #ifdef ENABLE_PKCS11
 385                         options.pkcs11_provider = xstrdup(optarg);
 386 #else
 387                         fprintf(stderr, "no support for PKCS#11.\n");
 388 #endif
 389                         break;
 390                 case 't':
 391                         if (tty_flag)
 392                                 force_tty_flag = 1;
 393                         tty_flag = 1;
 394                         break;
 395                 case 'v':
 396                         if (debug_flag == 0) {
 397                                 debug_flag = 1;
 398                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 399                         } else {
 400                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 401                                         options.log_level++;
 402                                 break;
 403                         }
 404                         /* FALLTHROUGH */
 405                 case 'V':
 406                         fprintf(stderr, "%s, %s\n",
 407                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 408                         if (opt == 'V')
 409                                 exit(0);
 410                         break;
 411                 case 'w':
 412                         if (options.tun_open == -1)
 413                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 414                         options.tun_local = a2tun(optarg, &options.tun_remote);
 415                         if (options.tun_local == SSH_TUNID_ERR) {
 416                                 fprintf(stderr,
 417                                     "Bad tun device '%s'\n", optarg);
 418                                 exit(255);
 419                         }
 420                         break;
 421                 case 'W':
 422                         if (stdio_forward_host != NULL)
 423                                 fatal("stdio forward already specified");
 424                         if (muxclient_command != 0)
 425                                 fatal("Cannot specify stdio forward with -O");
 426                         if (parse_forward(&fwd, optarg, 1, 0)) {
 427                                 stdio_forward_host = fwd.listen_host;
 428                                 stdio_forward_port = fwd.listen_port;
 429                                 xfree(fwd.connect_host);
 430                         } else {
 431                                 fprintf(stderr,
 432                                     "Bad stdio forwarding specification '%s'\n",
 433                                     optarg);
 434                                 exit(255);
 435                         }
 436                         no_tty_flag = 1;
 437                         no_shell_flag = 1;
 438                         options.clear_forwardings = 1;
 439                         options.exit_on_forward_failure = 1;
 440                         break;
 441                 case 'q':
 442                         options.log_level = SYSLOG_LEVEL_QUIET;
 443                         break;
 444                 case 'e':
 445                         if (optarg[0] == '^' && optarg[2] == 0 &&
 446                             (u_char) optarg[1] >= 64 &&
 447                             (u_char) optarg[1] < 128)
 448                                 options.escape_char = (u_char) optarg[1] & 31;
 449                         else if (strlen(optarg) == 1)
 450                                 options.escape_char = (u_char) optarg[0];
 451                         else if (strcmp(optarg, "none") == 0)
 452                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 453                         else {
 454                                 fprintf(stderr, "Bad escape character '%s'.\n",
 455                                     optarg);
 456                                 exit(255);
 457                         }
 458                         break;
 459                 case 'c':
 460                         if (ciphers_valid(optarg)) {
 461                                 /* SSH2 only */
 462                                 options.ciphers = xstrdup(optarg);
 463                                 options.cipher = SSH_CIPHER_INVALID;
 464                         } else {
 465                                 /* SSH1 only */
 466                                 options.cipher = cipher_number(optarg);
 467                                 if (options.cipher == -1) {
 468                                         fprintf(stderr,
 469                                             "Unknown cipher type '%s'\n",
 470                                             optarg);
 471                                         exit(255);
 472                                 }
 473                                 if (options.cipher == SSH_CIPHER_3DES)
 474                                         options.ciphers = "3des-cbc";
 475                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 476                                         options.ciphers = "blowfish-cbc";
 477                                 else
 478                                         options.ciphers = (char *)-1;
 479                         }
 480                         break;
 481                 case 'm':
 482                         if (mac_valid(optarg))
 483                                 options.macs = xstrdup(optarg);
 484                         else {
 485                                 fprintf(stderr, "Unknown mac type '%s'\n",
 486                                     optarg);
 487                                 exit(255);
 488                         }
 489                         break;
 490                 case 'M':
 491                         if (options.control_master == SSHCTL_MASTER_YES)
 492                                 options.control_master = SSHCTL_MASTER_ASK;
 493                         else
 494                                 options.control_master = SSHCTL_MASTER_YES;
 495                         break;
 496                 case 'p':
 497                         options.port = a2port(optarg);
 498                         if (options.port <= 0) {
 499                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 500                                 exit(255);
 501                         }
 502                         break;
 503                 case 'l':
 504                         options.user = optarg;
 505                         break;
 506
 507                 case 'L':
 508                         if (parse_forward(&fwd, optarg, 0, 0))
 509                                 add_local_forward(&options, &fwd);
 510                         else {
 511                                 fprintf(stderr,
 512                                     "Bad local forwarding specification '%s'\n",
 513                                     optarg);
 514                                 exit(255);
 515                         }
 516                         break;
 517
 518                 case 'R':
 519                         if (parse_forward(&fwd, optarg, 0, 1)) {
 520                                 add_remote_forward(&options, &fwd);
 521                         } else {
 522                                 fprintf(stderr,
 523                                     "Bad remote forwarding specification "
 524                                     "'%s'\n", optarg);
 525                                 exit(255);
 526                         }
 527                         break;
 528
 529                 case 'D':
 530                         if (parse_forward(&fwd, optarg, 1, 0)) {
 531                                 add_local_forward(&options, &fwd);
 532                         } else {
 533                                 fprintf(stderr,
 534                                     "Bad dynamic forwarding specification "
 535                                     "'%s'\n", optarg);
 536                                 exit(255);
 537                         }
 538                         break;
 539
 540                 case 'C':
 541                         options.compression = 1;
 542                         break;
 543                 case 'N':
 544                         no_shell_flag = 1;
 545                         no_tty_flag = 1;
 546                         break;
 547                 case 'o':
 548                         dummy = 1;
 549                         line = xstrdup(optarg);
 550                         if (process_config_line(&options, host ? host : "",
 551                             line, "command-line", 0, &dummy) != 0)
 552                                 exit(255);
 553                         xfree(line);
 554                         break;
 555                 case 'T':
 556                         no_tty_flag = 1;
 557                         /* ensure that the user doesn't try to backdoor a */
 558                         /* null cipher switch on an interactive session */
 559                         /* so explicitly disable it no matter what */
 560                         options.none_switch=0;
 561                         break;
 562                 case 's':
 563                         subsystem_flag = 1;
 564                         break;
 565                 case 'S':
 566                         if (options.control_path != NULL)
 567                                 free(options.control_path);
 568                         options.control_path = xstrdup(optarg);
 569                         break;
 570                 case 'b':
 571                         options.bind_address = optarg;
 572                         break;
 573                 case 'F':
 574                         config = optarg;
 575                         break;
 576                 default:
 577                         usage();
 578                 }
 579         }
 580
 581         ac -= optind;
 582         av += optind;
 583
 584         if (ac > 0 && !host) {
 585                 if (strrchr(*av, '@')) {
 586                         p = xstrdup(*av);
 587                         cp = strrchr(p, '@');
 588                         if (cp == NULL || cp == p)
 589                                 usage();
 590                         options.user = p;
 591                         *cp = '\0';
 592                         host = ++cp;
 593                 } else
 594                         host = *av;
 595                 if (ac > 1) {
 596                         optind = optreset = 1;
 597                         goto again;
 598                 }
 599                 ac--, av++;
 600         }
 601
 602         /* Check that we got a host name. */
 603         if (!host)
 604                 usage();
 605
 606         SSLeay_add_all_algorithms();
 607         ERR_load_crypto_strings();
 608
 609         /* Initialize the command to execute on remote host. */
 610         buffer_init(&command);
 611
 612         /*
 613          * Save the command to execute on the remote host in a buffer. There
 614          * is no limit on the length of the command, except by the maximum
 615          * packet size.  Also sets the tty flag if there is no command.
 616          */
 617         if (!ac) {
 618                 /* No command specified - execute shell on a tty. */
 619                 tty_flag = 1;
 620                 if (subsystem_flag) {
 621                         fprintf(stderr,
 622                             "You must specify a subsystem to invoke.\n");
 623                         usage();
 624                 }
 625         } else {
 626                 /* A command has been specified.  Store it into the buffer. */
 627                 for (i = 0; i < ac; i++) {
 628                         if (i)
 629                                 buffer_append(&command, " ", 1);
 630                         buffer_append(&command, av[i], strlen(av[i]));
 631                 }
 632         }
 633
 634         /* Cannot fork to background if no command. */
 635         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 636             !no_shell_flag)
 637                 fatal("Cannot fork into background without a command "
 638                     "to execute.");
 639
 640         /* Allocate a tty by default if no command specified. */
 641         if (buffer_len(&command) == 0)
 642                 tty_flag = 1;
 643
 644         /* Force no tty */
 645         if (no_tty_flag || muxclient_command != 0)
 646                 tty_flag = 0;
 647         /* Do not allocate a tty if stdin is not a tty. */
 648         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 649                 if (tty_flag)
 650                         logit("Pseudo-terminal will not be allocated because "
 651                             "stdin is not a terminal.");
 652                 tty_flag = 0;
 653         }
 654
 655         /*
 656          * Initialize "log" output.  Since we are the client all output
 657          * actually goes to stderr.
 658          */
 659         log_init(argv0,
 660             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 661             SYSLOG_FACILITY_USER, !use_syslog);
 662
 663         /*
 664          * Read per-user configuration file.  Ignore the system wide config
 665          * file if the user specifies a config file on the command line.
 666          */
 667         if (config != NULL) {
 668                 if (!read_config_file(config, host, &options, 0))
 669                         fatal("Can't open user config file %.100s: "
 670                             "%.100s", config, strerror(errno));
 671         } else {
 672                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 673                     _PATH_SSH_USER_CONFFILE);
 674                 if (r > 0 && (size_t)r < sizeof(buf))
 675                         (void)read_config_file(buf, host, &options, 1);
 676
 677                 /* Read systemwide configuration file after use config. */
 678                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 679                     &options, 0);
 680         }
 681
 682         /* Fill configuration defaults. */
 683         fill_default_options(&options);
 684
 685         channel_set_af(options.address_family);
 686
 687         /* reinit */
 688         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 689
 690         seed_rng();
 691
 692         if (options.user == NULL)
 693                 options.user = xstrdup(pw->pw_name);
 694
 695         /* Get default port if port has not been set. */
 696         if (options.port == 0) {
 697                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 698                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 699         }
 700
 701         if (options.hostname != NULL) {
 702                 host = percent_expand(options.hostname,
 703                     "h", host, (char *)NULL);
 704         }
 705
 706         if (options.local_command != NULL) {
 707                 char thishost[NI_MAXHOST];
 708
 709                 if (gethostname(thishost, sizeof(thishost)) == -1)
 710                         fatal("gethostname: %s", strerror(errno));
 711                 snprintf(buf, sizeof(buf), "%d", options.port);
 712                 debug3("expanding LocalCommand: %s", options.local_command);
 713                 cp = options.local_command;
 714                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 715                     "h", host, "l", thishost, "n", host, "r", options.user,
 716                     "p", buf, "u", pw->pw_name, (char *)NULL);
 717                 debug3("expanded LocalCommand: %s", options.local_command);
 718                 xfree(cp);
 719         }
 720
 721         /* force lowercase for hostkey matching */
 722         if (options.host_key_alias != NULL) {
 723                 for (p = options.host_key_alias; *p; p++)
 724                         if (isupper(*p))
 725                                 *p = (char)tolower(*p);
 726         }
 727
 728         if (options.proxy_command != NULL &&
 729             strcmp(options.proxy_command, "none") == 0) {
 730                 xfree(options.proxy_command);
 731                 options.proxy_command = NULL;
 732         }
 733         if (options.control_path != NULL &&
 734             strcmp(options.control_path, "none") == 0) {
 735                 xfree(options.control_path);
 736                 options.control_path = NULL;
 737         }
 738
 739         if (options.control_path != NULL) {
 740                 char thishost[NI_MAXHOST];
 741
 742                 if (gethostname(thishost, sizeof(thishost)) == -1)
 743                         fatal("gethostname: %s", strerror(errno));
 744                 snprintf(buf, sizeof(buf), "%d", options.port);
 745                 cp = tilde_expand_filename(options.control_path,
 746                     original_real_uid);
 747                 xfree(options.control_path);
 748                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 749                     "r", options.user, "l", thishost, (char *)NULL);
 750                 xfree(cp);
 751         }
 752         if (muxclient_command != 0 && options.control_path == NULL)
 753                 fatal("No ControlPath specified for \"-O\" command");
 754         if (options.control_path != NULL)
 755                 muxclient(options.control_path);
 756
 757         timeout_ms = options.connection_timeout * 1000;
 758
 759         /* Open a connection to the remote host. */
 760         if (ssh_connect(host, &hostaddr, options.port,
 761             options.address_family, options.connection_attempts, &timeout_ms,
 762             options.tcp_keep_alive,
 763 #ifdef HAVE_CYGWIN
 764             options.use_privileged_port,
 765 #else
 766             original_effective_uid == 0 && options.use_privileged_port,
 767 #endif
 768             options.proxy_command) != 0)
 769                 exit(255);
 770
 771         if (timeout_ms > 0)
 772                 debug3("timeout: %d ms remain after connect", timeout_ms);
 773
 774         /*
 775          * If we successfully made the connection, load the host private key
 776          * in case we will need it later for combined rsa-rhosts
 777          * authentication. This must be done before releasing extra
 778          * privileges, because the file is only readable by root.
 779          * If we cannot access the private keys, load the public keys
 780          * instead and try to execute the ssh-keysign helper instead.
 781          */
 782         sensitive_data.nkeys = 0;
 783         sensitive_data.keys = NULL;
 784         sensitive_data.external_keysign = 0;
 785         if (options.rhosts_rsa_authentication ||
 786             options.hostbased_authentication) {
 787                 sensitive_data.nkeys = 5;
 788                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 789                     sizeof(Key));
 790
 791                 PRIV_START;
 792                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 793                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 794                 sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
 795                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 796                 sensitive_data.keys[2] = key_load_private_cert(KEY_RSA,
 797                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 798                 sensitive_data.keys[3] = key_load_private_type(KEY_DSA,
 799                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 800                 sensitive_data.keys[4] = key_load_private_type(KEY_RSA,
 801                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 802                 PRIV_END;
 803
 804                 if (options.hostbased_authentication == 1 &&
 805                     sensitive_data.keys[0] == NULL &&
 806                     sensitive_data.keys[3] == NULL &&
 807                     sensitive_data.keys[4] == NULL) {
 808                         sensitive_data.keys[1] = key_load_cert(
 809                             _PATH_HOST_DSA_KEY_FILE);
 810                         sensitive_data.keys[2] = key_load_cert(
 811                             _PATH_HOST_RSA_KEY_FILE);
 812                         sensitive_data.keys[3] = key_load_public(
 813                             _PATH_HOST_DSA_KEY_FILE, NULL);
 814                         sensitive_data.keys[4] = key_load_public(
 815                             _PATH_HOST_RSA_KEY_FILE, NULL);
 816                         sensitive_data.external_keysign = 1;
 817                 }
 818         }
 819         /*
 820          * Get rid of any extra privileges that we may have.  We will no
 821          * longer need them.  Also, extra privileges could make it very hard
 822          * to read identity files and other non-world-readable files from the
 823          * user's home directory if it happens to be on a NFS volume where
 824          * root is mapped to nobody.
 825          */
 826         if (original_effective_uid == 0) {
 827                 PRIV_START;
 828                 permanently_set_uid(pw);
 829         }
 830
 831         /*
 832          * Now that we are back to our own permissions, create ~/.ssh
 833          * directory if it doesn't already exist.
 834          */
 835         r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
 836             strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 837         if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0)
 838                 if (mkdir(buf, 0700) < 0)
 839                         error("Could not create directory '%.200s'.", buf);
 840
 841         /* load options.identity_files */
 842         load_public_identity_files();
 843
 844         /* Expand ~ in known host file names. */
 845         /* XXX mem-leaks: */
 846         options.system_hostfile =
 847             tilde_expand_filename(options.system_hostfile, original_real_uid);
 848         options.user_hostfile =
 849             tilde_expand_filename(options.user_hostfile, original_real_uid);
 850         options.system_hostfile2 =
 851             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 852         options.user_hostfile2 =
 853             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 854
 855         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 856
 857         /* Log into the remote system.  Never returns if the login fails. */
 858         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 859             pw, timeout_ms);
 860
 861         if (packet_connection_is_on_socket()) {
 862                 verbose("Authenticated to %s ([%s]:%d).", host,
 863                     get_remote_ipaddr(), get_remote_port());
 864         } else {
 865                 verbose("Authenticated to %s (via proxy).", host);
 866         }
 867
 868         /* We no longer need the private host keys.  Clear them now. */
 869         if (sensitive_data.nkeys != 0) {
 870                 for (i = 0; i < sensitive_data.nkeys; i++) {
 871                         if (sensitive_data.keys[i] != NULL) {
 872                                 /* Destroys contents safely */
 873                                 debug3("clear hostkey %d", i);
 874                                 key_free(sensitive_data.keys[i]);
 875                                 sensitive_data.keys[i] = NULL;
 876                         }
 877                 }
 878                 xfree(sensitive_data.keys);
 879         }
 880         for (i = 0; i < options.num_identity_files; i++) {
 881                 if (options.identity_files[i]) {
 882                         xfree(options.identity_files[i]);
 883                         options.identity_files[i] = NULL;
 884                 }
 885                 if (options.identity_keys[i]) {
 886                         key_free(options.identity_keys[i]);
 887                         options.identity_keys[i] = NULL;
 888                 }
 889         }
 890
 891         exit_status = compat20 ? ssh_session2() : ssh_session();
 892         packet_close();
 893
 894         if (options.control_path != NULL && muxserver_sock != -1)
 895                 unlink(options.control_path);
 896
 897         /*
 898          * Send SIGHUP to proxy command if used. We don't wait() in
 899          * case it hangs and instead rely on init to reap the child
 900          */
 901         if (proxy_command_pid > 1)
 902                 kill(proxy_command_pid, SIGHUP);
 903
 904         return exit_status;
 905 }
 906
 907 static void
 908 control_persist_detach(void)
 909 {
 910         pid_t pid;
 911         int devnull;
 912
 913         debug("%s: backgrounding master process", __func__);
 914
 915         /*
 916          * master (current process) into the background, and make the
 917          * foreground process a client of the backgrounded master.
 918          */
 919         switch ((pid = fork())) {
 920         case -1:
 921                 fatal("%s: fork: %s", __func__, strerror(errno));
 922         case 0:
 923                 /* Child: master process continues mainloop */
 924                 break;
 925         default:
 926                 /* Parent: set up mux slave to connect to backgrounded master */
 927                 debug2("%s: background process is %ld", __func__, (long)pid);
 928                 stdin_null_flag = ostdin_null_flag;
 929                 no_shell_flag = ono_shell_flag;
 930                 no_tty_flag = ono_tty_flag;
 931                 tty_flag = otty_flag;
 932                 close(muxserver_sock);
 933                 muxserver_sock = -1;
 934                 muxclient(options.control_path);
 935                 /* muxclient() doesn't return on success. */
 936                 fatal("Failed to connect to new control master");
 937         }
 938         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
 939                 error("%s: open(\"/dev/null\"): %s", __func__,
 940                     strerror(errno));
 941         } else {
 942                 if (dup2(devnull, STDIN_FILENO) == -1 ||
 943                     dup2(devnull, STDOUT_FILENO) == -1)
 944                         error("%s: dup2: %s", __func__, strerror(errno));
 945                 if (devnull > STDERR_FILENO)
 946                         close(devnull);
 947         }
 948 }
 949
 950 /* Do fork() after authentication. Used by "ssh -f" */
 951 static void
 952 fork_postauth(void)
 953 {
 954         if (need_controlpersist_detach)
 955                 control_persist_detach();
 956         debug("forking to background");
 957         fork_after_authentication_flag = 0;
 958         if (daemon(1, 1) < 0)
 959                 fatal("daemon() failed: %.200s", strerror(errno));
 960 }
 961
 962 /* Callback for remote forward global requests */
 963 static void
 964 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 965 {
 966         Forward *rfwd = (Forward *)ctxt;
 967
 968         /* XXX verbose() on failure? */
 969         debug("remote forward %s for: listen %d, connect %s:%d",
 970             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
 971             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
 972         if (type == SSH2_MSG_REQUEST_SUCCESS && rfwd->listen_port == 0) {
 973                 rfwd->allocated_port = packet_get_int();
 974                 logit("Allocated port %u for remote forward to %s:%d",
 975                     rfwd->allocated_port,
 976                     rfwd->connect_host, rfwd->connect_port);
 977         }
 978
 979         if (type == SSH2_MSG_REQUEST_FAILURE) {
 980                 if (options.exit_on_forward_failure)
 981                         fatal("Error: remote port forwarding failed for "
 982                             "listen port %d", rfwd->listen_port);
 983                 else
 984                         logit("Warning: remote port forwarding failed for "
 985                             "listen port %d", rfwd->listen_port);
 986         }
 987         if (++remote_forward_confirms_received == options.num_remote_forwards) {
 988                 debug("All remote forwarding requests processed");
 989                 if (fork_after_authentication_flag)
 990                         fork_postauth();
 991         }
 992 }
 993
 994 static void
 995 client_cleanup_stdio_fwd(int id, void *arg)
 996 {
 997         debug("stdio forwarding: done");
 998         cleanup_exit(0);
 999 }
1000
1001 static int
1002 client_setup_stdio_fwd(const char *host_to_connect, u_short port_to_connect)
1003 {
1004         Channel *c;
1005         int in, out;
1006
1007         debug3("client_setup_stdio_fwd %s:%d", host_to_connect,
1008             port_to_connect);
1009
1010         in = dup(STDIN_FILENO);
1011         out = dup(STDOUT_FILENO);
1012         if (in < 0 || out < 0)
1013                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1014
1015         if ((c = channel_connect_stdio_fwd(host_to_connect, port_to_connect,
1016             in, out)) == NULL)
1017                 return 0;
1018         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1019         return 1;
1020 }
1021
1022 static void
1023 ssh_init_forwarding(void)
1024 {
1025         int success = 0;
1026         int i;
1027
1028         if (stdio_forward_host != NULL) {
1029                 if (!compat20) {
1030                         fatal("stdio forwarding require Protocol 2");
1031                 }
1032                 if (!client_setup_stdio_fwd(stdio_forward_host,
1033                     stdio_forward_port))
1034                         fatal("Failed to connect in stdio forward mode.");
1035         }
1036
1037         /* Initiate local TCP/IP port forwardings. */
1038         for (i = 0; i < options.num_local_forwards; i++) {
1039                 debug("Local connections to %.200s:%d forwarded to remote "
1040                     "address %.200s:%d",
1041                     (options.local_forwards[i].listen_host == NULL) ?
1042                     (options.gateway_ports ? "*" : "LOCALHOST") :
1043                     options.local_forwards[i].listen_host,
1044                     options.local_forwards[i].listen_port,
1045                     options.local_forwards[i].connect_host,
1046                     options.local_forwards[i].connect_port);
1047                 success += channel_setup_local_fwd_listener(
1048                     options.local_forwards[i].listen_host,
1049                     options.local_forwards[i].listen_port,
1050                     options.local_forwards[i].connect_host,
1051                     options.local_forwards[i].connect_port,
1052                     options.gateway_ports);
1053         }
1054         if (i > 0 && success != i && options.exit_on_forward_failure)
1055                 fatal("Could not request local forwarding.");
1056         if (i > 0 && success == 0)
1057                 error("Could not request local forwarding.");
1058
1059         /* Initiate remote TCP/IP port forwardings. */
1060         for (i = 0; i < options.num_remote_forwards; i++) {
1061                 debug("Remote connections from %.200s:%d forwarded to "
1062                     "local address %.200s:%d",
1063                     (options.remote_forwards[i].listen_host == NULL) ?
1064                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1065                     options.remote_forwards[i].listen_port,
1066                     options.remote_forwards[i].connect_host,
1067                     options.remote_forwards[i].connect_port);
1068                 if (channel_request_remote_forwarding(
1069                     options.remote_forwards[i].listen_host,
1070                     options.remote_forwards[i].listen_port,
1071                     options.remote_forwards[i].connect_host,
1072                     options.remote_forwards[i].connect_port) < 0) {
1073                         if (options.exit_on_forward_failure)
1074                                 fatal("Could not request remote forwarding.");
1075                         else
1076                                 logit("Warning: Could not request remote "
1077                                     "forwarding.");
1078                 }
1079                 client_register_global_confirm(ssh_confirm_remote_forward,
1080                     &options.remote_forwards[i]);
1081         }
1082
1083         /* Initiate tunnel forwarding. */
1084         if (options.tun_open != SSH_TUNMODE_NO) {
1085                 if (client_request_tun_fwd(options.tun_open,
1086                     options.tun_local, options.tun_remote) == -1) {
1087                         if (options.exit_on_forward_failure)
1088                                 fatal("Could not request tunnel forwarding.");
1089                         else
1090                                 error("Could not request tunnel forwarding.");
1091                 }
1092         }
1093 }
1094
1095 static void
1096 check_agent_present(void)
1097 {
1098         if (options.forward_agent) {
1099                 /* Clear agent forwarding if we don't have an agent. */
1100                 if (!ssh_agent_present())
1101                         options.forward_agent = 0;
1102         }
1103 }
1104
1105 static int
1106 ssh_session(void)
1107 {
1108         int type;
1109         int interactive = 0;
1110         int have_tty = 0;
1111         struct winsize ws;
1112         char *cp;
1113         const char *display;
1114
1115         /* Enable compression if requested. */
1116         if (options.compression) {
1117                 debug("Requesting compression at level %d.",
1118                     options.compression_level);
1119
1120                 if (options.compression_level < 1 ||
1121                     options.compression_level > 9)
1122                         fatal("Compression level must be from 1 (fast) to "
1123                             "9 (slow, best).");
1124
1125                 /* Send the request. */
1126                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1127                 packet_put_int(options.compression_level);
1128                 packet_send();
1129                 packet_write_wait();
1130                 type = packet_read();
1131                 if (type == SSH_SMSG_SUCCESS)
1132                         packet_start_compression(options.compression_level);
1133                 else if (type == SSH_SMSG_FAILURE)
1134                         logit("Warning: Remote host refused compression.");
1135                 else
1136                         packet_disconnect("Protocol error waiting for "
1137                             "compression response.");
1138         }
1139         /* Allocate a pseudo tty if appropriate. */
1140         if (tty_flag) {
1141                 debug("Requesting pty.");
1142
1143                 /* Start the packet. */
1144                 packet_start(SSH_CMSG_REQUEST_PTY);
1145
1146                 /* Store TERM in the packet.  There is no limit on the
1147                    length of the string. */
1148                 cp = getenv("TERM");
1149                 if (!cp)
1150                         cp = "";
1151                 packet_put_cstring(cp);
1152
1153                 /* Store window size in the packet. */
1154                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1155                         memset(&ws, 0, sizeof(ws));
1156                 packet_put_int((u_int)ws.ws_row);
1157                 packet_put_int((u_int)ws.ws_col);
1158                 packet_put_int((u_int)ws.ws_xpixel);
1159                 packet_put_int((u_int)ws.ws_ypixel);
1160
1161                 /* Store tty modes in the packet. */
1162                 tty_make_modes(fileno(stdin), NULL);
1163
1164                 /* Send the packet, and wait for it to leave. */
1165                 packet_send();
1166                 packet_write_wait();
1167
1168                 /* Read response from the server. */
1169                 type = packet_read();
1170                 if (type == SSH_SMSG_SUCCESS) {
1171                         interactive = 1;
1172                         have_tty = 1;
1173                 } else if (type == SSH_SMSG_FAILURE)
1174                         logit("Warning: Remote host failed or refused to "
1175                             "allocate a pseudo tty.");
1176                 else
1177                         packet_disconnect("Protocol error waiting for pty "
1178                             "request response.");
1179         }
1180         /* Request X11 forwarding if enabled and DISPLAY is set. */
1181         display = getenv("DISPLAY");
1182         if (options.forward_x11 && display != NULL) {
1183                 char *proto, *data;
1184                 /* Get reasonable local authentication information. */
1185                 client_x11_get_proto(display, options.xauth_location,
1186                     options.forward_x11_trusted,
1187                     options.forward_x11_timeout,
1188                     &proto, &data);
1189                 /* Request forwarding with authentication spoofing. */
1190                 debug("Requesting X11 forwarding with authentication "
1191                     "spoofing.");
1192                 x11_request_forwarding_with_spoofing(0, display, proto, data);
1193
1194                 /* Read response from the server. */
1195                 type = packet_read();
1196                 if (type == SSH_SMSG_SUCCESS) {
1197                         interactive = 1;
1198                 } else if (type == SSH_SMSG_FAILURE) {
1199                         logit("Warning: Remote host denied X11 forwarding.");
1200                 } else {
1201                         packet_disconnect("Protocol error waiting for X11 "
1202                             "forwarding");
1203                 }
1204         }
1205         /* Tell the packet module whether this is an interactive session. */
1206         packet_set_interactive(interactive);
1207
1208         /* Request authentication agent forwarding if appropriate. */
1209         check_agent_present();
1210
1211         if (options.forward_agent) {
1212                 debug("Requesting authentication agent forwarding.");
1213                 auth_request_forwarding();
1214
1215                 /* Read response from the server. */
1216                 type = packet_read();
1217                 packet_check_eom();
1218                 if (type != SSH_SMSG_SUCCESS)
1219                         logit("Warning: Remote host denied authentication agent forwarding.");
1220         }
1221
1222         /* Initiate port forwardings. */
1223         ssh_init_forwarding();
1224
1225         /* Execute a local command */
1226         if (options.local_command != NULL &&
1227             options.permit_local_command)
1228                 ssh_local_cmd(options.local_command);
1229
1230         /*
1231          * If requested and we are not interested in replies to remote
1232          * forwarding requests, then let ssh continue in the background.
1233          */
1234         if (fork_after_authentication_flag) {
1235                 if (options.exit_on_forward_failure &&
1236                     options.num_remote_forwards > 0) {
1237                         debug("deferring postauth fork until remote forward "
1238                             "confirmation received");
1239                 } else
1240                         fork_postauth();
1241         }
1242
1243         /*
1244          * If a command was specified on the command line, execute the
1245          * command now. Otherwise request the server to start a shell.
1246          */
1247         if (buffer_len(&command) > 0) {
1248                 int len = buffer_len(&command);
1249                 if (len > 900)
1250                         len = 900;
1251                 debug("Sending command: %.*s", len,
1252                     (u_char *)buffer_ptr(&command));
1253                 packet_start(SSH_CMSG_EXEC_CMD);
1254                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1255                 packet_send();
1256                 packet_write_wait();
1257         } else {
1258                 debug("Requesting shell.");
1259                 packet_start(SSH_CMSG_EXEC_SHELL);
1260                 packet_send();
1261                 packet_write_wait();
1262         }
1263
1264         /* Enter the interactive session. */
1265         return client_loop(have_tty, tty_flag ?
1266             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1267 }
1268
1269 /* request pty/x11/agent/tcpfwd/shell for channel */
1270 static void
1271 ssh_session2_setup(int id, int success, void *arg)
1272 {
1273         extern char **environ;
1274         const char *display;
1275         int interactive = tty_flag;
1276
1277         if (!success)
1278                 return; /* No need for error message, channels code sens one */
1279
1280         display = getenv("DISPLAY");
1281         if (options.forward_x11 && display != NULL) {
1282                 char *proto, *data;
1283                 /* Get reasonable local authentication information. */
1284                 client_x11_get_proto(display, options.xauth_location,
1285                     options.forward_x11_trusted,
1286                     options.forward_x11_timeout, &proto, &data);
1287                 /* Request forwarding with authentication spoofing. */
1288                 debug("Requesting X11 forwarding with authentication "
1289                     "spoofing.");
1290                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1291                 interactive = 1;
1292                 /* XXX wait for reply */
1293         }
1294
1295         check_agent_present();
1296         if (options.forward_agent) {
1297                 debug("Requesting authentication agent forwarding.");
1298                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1299                 packet_send();
1300         }
1301
1302         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1303             NULL, fileno(stdin), &command, environ);
1304
1305         packet_set_interactive(interactive);
1306 }
1307
1308 /* open new channel for a session */
1309 static int
1310 ssh_session2_open(void)
1311 {
1312         Channel *c;
1313         int window, packetmax, in, out, err;
1314         int sock;
1315         int socksize;
1316         int socksizelen = sizeof(int);
1317
1318         if (stdin_null_flag) {
1319                 in = open(_PATH_DEVNULL, O_RDONLY);
1320         } else {
1321                 in = dup(STDIN_FILENO);
1322         }
1323         out = dup(STDOUT_FILENO);
1324         err = dup(STDERR_FILENO);
1325
1326         if (in < 0 || out < 0 || err < 0)
1327                 fatal("dup() in/out/err failed");
1328
1329         /* enable nonblocking unless tty */
1330         if (!isatty(in))
1331                 set_nonblock(in);
1332         if (!isatty(out))
1333                 set_nonblock(out);
1334         if (!isatty(err))
1335                 set_nonblock(err);
1336
1337         /* we need to check to see if what they want to do about buffer */
1338         /* sizes here. In a hpn to nonhpn connection we want to limit */
1339         /* the window size to something reasonable in case the far side */
1340         /* has the large window bug. In hpn to hpn connection we want to */
1341         /* use the max window size but allow the user to override it */
1342         /* lastly if they disabled hpn then use the ssh std window size */
1343
1344         /* so why don't we just do a getsockopt() here and set the */
1345         /* ssh window to that? In the case of a autotuning receive */
1346         /* window the window would get stuck at the initial buffer */
1347         /* size generally less than 96k. Therefore we need to set the */
1348         /* maximum ssh window size to the maximum hpn buffer size */
1349         /* unless the user has specifically set the tcprcvbufpoll */
1350         /* to no. In which case we *can* just set the window to the */
1351         /* minimum of the hpn buffer size and tcp receive buffer size */
1352
1353         if (tty_flag)
1354                 options.hpn_buffer_size = CHAN_SES_WINDOW_DEFAULT;
1355         else
1356                 options.hpn_buffer_size = 2*1024*1024;
1357
1358         if (datafellows & SSH_BUG_LARGEWINDOW)
1359         {
1360                 debug("HPN to Non-HPN Connection");
1361         }
1362         else
1363         {
1364                 if (options.tcp_rcv_buf_poll <= 0)
1365                 {
1366                         sock = socket(AF_INET, SOCK_STREAM, 0);
1367                         getsockopt(sock, SOL_SOCKET, SO_RCVBUF,
1368                                    &socksize, &socksizelen);
1369                         close(sock);
1370                         debug("socksize %d", socksize);
1371                         options.hpn_buffer_size = socksize;
1372                         debug ("HPNBufferSize set to TCP RWIN: %d", options.hpn_buffer_size);
1373                 }
1374                 else
1375                 {
1376                         if (options.tcp_rcv_buf > 0)
1377                         {
1378                                 /*create a socket but don't connect it */
1379                                 /* we use that the get the rcv socket size */
1380                                 sock = socket(AF_INET, SOCK_STREAM, 0);
1381                                 /* if they are using the tcp_rcv_buf option */
1382                                 /* attempt to set the buffer size to that */
1383                                 if (options.tcp_rcv_buf)
1384                                         setsockopt(sock, SOL_SOCKET, SO_RCVBUF, (void *)&options.tcp_rcv_buf,
1385                                                    sizeof(options.tcp_rcv_buf));
1386                                 getsockopt(sock, SOL_SOCKET, SO_RCVBUF,
1387                                            &socksize, &socksizelen);
1388                                 close(sock);
1389                                 debug("socksize %d", socksize);
1390                                 options.hpn_buffer_size = socksize;
1391                                 debug ("HPNBufferSize set to user TCPRcvBuf: %d", options.hpn_buffer_size);
1392                         }
1393                 }
1394
1395         }
1396
1397         debug("Final hpn_buffer_size = %d", options.hpn_buffer_size);
1398
1399         window = options.hpn_buffer_size;
1400
1401         channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1402
1403         packetmax = CHAN_SES_PACKET_DEFAULT;
1404         if (tty_flag) {
1405                 window = 4*CHAN_SES_PACKET_DEFAULT;
1406                 window >>= 1;
1407                 packetmax >>= 1;
1408         }
1409         c = channel_new(
1410             "session", SSH_CHANNEL_OPENING, in, out, err,
1411             window, packetmax, CHAN_EXTENDED_WRITE,
1412             "client-session", /*nonblock*/0);
1413         if ((options.tcp_rcv_buf_poll > 0) && (!options.hpn_disabled)) {
1414                 c->dynamic_window = 1;
1415                 debug ("Enabled Dynamic Window Scaling\n");
1416         }
1417         debug3("ssh_session2_open: channel_new: %d", c->self);
1418
1419         channel_send_open(c->self);
1420         if (!no_shell_flag)
1421                 channel_register_open_confirm(c->self,
1422                     ssh_session2_setup, NULL);
1423
1424         return c->self;
1425 }
1426
1427 static int
1428 ssh_session2(void)
1429 {
1430         int id = -1;
1431
1432         /* XXX should be pre-session */
1433         ssh_init_forwarding();
1434
1435         /* Start listening for multiplex clients */
1436         muxserver_listen();
1437
1438         /*
1439          * If we are in control persist mode, then prepare to background
1440          * ourselves and have a foreground client attach as a control
1441          * slave. NB. we must save copies of the flags that we override for
1442          * the backgrounding, since we defer attachment of the slave until
1443          * after the connection is fully established (in particular,
1444          * async rfwd replies have been received for ExitOnForwardFailure).
1445          */
1446         if (options.control_persist && muxserver_sock != -1) {
1447                 ostdin_null_flag = stdin_null_flag;
1448                 ono_shell_flag = no_shell_flag;
1449                 ono_tty_flag = no_tty_flag;
1450                 otty_flag = tty_flag;
1451                 stdin_null_flag = 1;
1452                 no_shell_flag = 1;
1453                 no_tty_flag = 1;
1454                 tty_flag = 0;
1455                 if (!fork_after_authentication_flag)
1456                         need_controlpersist_detach = 1;
1457                 fork_after_authentication_flag = 1;
1458         }
1459
1460         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1461                 id = ssh_session2_open();
1462
1463         /* If we don't expect to open a new session, then disallow it */
1464         if (options.control_master == SSHCTL_MASTER_NO &&
1465             (datafellows & SSH_NEW_OPENSSH)) {
1466                 debug("Requesting no-more-sessions@openssh.com");
1467                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1468                 packet_put_cstring("no-more-sessions@openssh.com");
1469                 packet_put_char(0);
1470                 packet_send();
1471         }
1472
1473         /* Execute a local command */
1474         if (options.local_command != NULL &&
1475             options.permit_local_command)
1476                 ssh_local_cmd(options.local_command);
1477
1478         /*
1479          * If requested and we are not interested in replies to remote
1480          * forwarding requests, then let ssh continue in the background.
1481          */
1482         if (fork_after_authentication_flag) {
1483                 if (options.exit_on_forward_failure &&
1484                     options.num_remote_forwards > 0) {
1485                         debug("deferring postauth fork until remote forward "
1486                             "confirmation received");
1487                 } else
1488                         fork_postauth();
1489         }
1490
1491         if (options.use_roaming)
1492                 request_roaming();
1493
1494         return client_loop(tty_flag, tty_flag ?
1495             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1496 }
1497
1498 static void
1499 load_public_identity_files(void)
1500 {
1501         char *filename, *cp, thishost[NI_MAXHOST];
1502         char *pwdir = NULL, *pwname = NULL;
1503         int i = 0;
1504         Key *public;
1505         struct passwd *pw;
1506         u_int n_ids;
1507         char *identity_files[SSH_MAX_IDENTITY_FILES];
1508         Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1509 #ifdef ENABLE_PKCS11
1510         Key **keys;
1511         int nkeys;
1512 #endif /* PKCS11 */
1513
1514         n_ids = 0;
1515         bzero(identity_files, sizeof(identity_files));
1516         bzero(identity_keys, sizeof(identity_keys));
1517
1518 #ifdef ENABLE_PKCS11
1519         if (options.pkcs11_provider != NULL &&
1520             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1521             (pkcs11_init(!options.batch_mode) == 0) &&
1522             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1523             &keys)) > 0) {
1524                 for (i = 0; i < nkeys; i++) {
1525                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1526                                 key_free(keys[i]);
1527                                 continue;
1528                         }
1529                         identity_keys[n_ids] = keys[i];
1530                         identity_files[n_ids] =
1531                             xstrdup(options.pkcs11_provider); /* XXX */
1532                         n_ids++;
1533                 }
1534                 xfree(keys);
1535         }
1536 #endif /* ENABLE_PKCS11 */
1537         if ((pw = getpwuid(original_real_uid)) == NULL)
1538                 fatal("load_public_identity_files: getpwuid failed");
1539         pwname = xstrdup(pw->pw_name);
1540         pwdir = xstrdup(pw->pw_dir);
1541         if (gethostname(thishost, sizeof(thishost)) == -1)
1542                 fatal("load_public_identity_files: gethostname: %s",
1543                     strerror(errno));
1544         for (i = 0; i < options.num_identity_files; i++) {
1545                 if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1546                         xfree(options.identity_files[i]);
1547                         continue;
1548                 }
1549                 cp = tilde_expand_filename(options.identity_files[i],
1550                     original_real_uid);
1551                 filename = percent_expand(cp, "d", pwdir,
1552                     "u", pwname, "l", thishost, "h", host,
1553                     "r", options.user, (char *)NULL);
1554                 xfree(cp);
1555                 public = key_load_public(filename, NULL);
1556                 debug("identity file %s type %d", filename,
1557                     public ? public->type : -1);
1558                 xfree(options.identity_files[i]);
1559                 identity_files[n_ids] = filename;
1560                 identity_keys[n_ids] = public;
1561
1562                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
1563                         continue;
1564
1565                 /* Try to add the certificate variant too */
1566                 xasprintf(&cp, "%s-cert", filename);
1567                 public = key_load_public(cp, NULL);
1568                 debug("identity file %s type %d", cp,
1569                     public ? public->type : -1);
1570                 if (public == NULL) {
1571                         xfree(cp);
1572                         continue;
1573                 }
1574                 if (!key_is_cert(public)) {
1575                         debug("%s: key %s type %s is not a certificate",
1576                             __func__, cp, key_type(public));
1577                         key_free(public);
1578                         xfree(cp);
1579                         continue;
1580                 }
1581                 identity_keys[n_ids] = public;
1582                 /* point to the original path, most likely the private key */
1583                 identity_files[n_ids] = xstrdup(filename);
1584                 n_ids++;
1585         }
1586         options.num_identity_files = n_ids;
1587         memcpy(options.identity_files, identity_files, sizeof(identity_files));
1588         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
1589
1590         bzero(pwname, strlen(pwname));
1591         xfree(pwname);
1592         bzero(pwdir, strlen(pwdir));
1593         xfree(pwdir);
1594 }