crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.370 2012/07/06 01:47:38 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                         if (options.num_identity_files >=
 411                             SSH_MAX_IDENTITY_FILES)
 412                                 fatal("Too many identity files specified "
 413                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 414                         options.identity_files[options.num_identity_files++] =
 415                             xstrdup(optarg);
 416                         break;
 417                 case 'I':
 418 #ifdef ENABLE_PKCS11
 419                         options.pkcs11_provider = xstrdup(optarg);
 420 #else
 421                         fprintf(stderr, "no support for PKCS#11.\n");
 422 #endif
 423                         break;
 424                 case 't':
 425                         if (options.request_tty == REQUEST_TTY_YES)
 426                                 options.request_tty = REQUEST_TTY_FORCE;
 427                         else
 428                                 options.request_tty = REQUEST_TTY_YES;
 429                         break;
 430                 case 'v':
 431                         if (debug_flag == 0) {
 432                                 debug_flag = 1;
 433                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 434                         } else {
 435                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 436                                         options.log_level++;
 437                                 break;
 438                         }
 439                         /* FALLTHROUGH */
 440                 case 'V':
 441                         if (options.version_addendum &&
 442                             *options.version_addendum != '\0')
 443                                 fprintf(stderr, "%s%s %s, %s\n", SSH_RELEASE,
 444                                     options.hpn_disabled ? "" : SSH_VERSION_HPN,
 445                                     options.version_addendum,
 446                                     SSLeay_version(SSLEAY_VERSION));
 447                         else
 448                                 fprintf(stderr, "%s%s, %s\n", SSH_RELEASE,
 449                                     options.hpn_disabled ? "" : SSH_VERSION_HPN,
 450                                     SSLeay_version(SSLEAY_VERSION));
 451                         if (opt == 'V')
 452                                 exit(0);
 453                         break;
 454                 case 'w':
 455                         if (options.tun_open == -1)
 456                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 457                         options.tun_local = a2tun(optarg, &options.tun_remote);
 458                         if (options.tun_local == SSH_TUNID_ERR) {
 459                                 fprintf(stderr,
 460                                     "Bad tun device '%s'\n", optarg);
 461                                 exit(255);
 462                         }
 463                         break;
 464                 case 'W':
 465                         if (stdio_forward_host != NULL)
 466                                 fatal("stdio forward already specified");
 467                         if (muxclient_command != 0)
 468                                 fatal("Cannot specify stdio forward with -O");
 469                         if (parse_forward(&fwd, optarg, 1, 0)) {
 470                                 stdio_forward_host = fwd.listen_host;
 471                                 stdio_forward_port = fwd.listen_port;
 472                                 xfree(fwd.connect_host);
 473                         } else {
 474                                 fprintf(stderr,
 475                                     "Bad stdio forwarding specification '%s'\n",
 476                                     optarg);
 477                                 exit(255);
 478                         }
 479                         options.request_tty = REQUEST_TTY_NO;
 480                         no_shell_flag = 1;
 481                         options.clear_forwardings = 1;
 482                         options.exit_on_forward_failure = 1;
 483                         break;
 484                 case 'q':
 485                         options.log_level = SYSLOG_LEVEL_QUIET;
 486                         break;
 487                 case 'e':
 488                         if (optarg[0] == '^' && optarg[2] == 0 &&
 489                             (u_char) optarg[1] >= 64 &&
 490                             (u_char) optarg[1] < 128)
 491                                 options.escape_char = (u_char) optarg[1] & 31;
 492                         else if (strlen(optarg) == 1)
 493                                 options.escape_char = (u_char) optarg[0];
 494                         else if (strcmp(optarg, "none") == 0)
 495                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 496                         else {
 497                                 fprintf(stderr, "Bad escape character '%s'.\n",
 498                                     optarg);
 499                                 exit(255);
 500                         }
 501                         break;
 502                 case 'c':
 503                         if (ciphers_valid(optarg)) {
 504                                 /* SSH2 only */
 505                                 options.ciphers = xstrdup(optarg);
 506                                 options.cipher = SSH_CIPHER_INVALID;
 507                         } else {
 508                                 /* SSH1 only */
 509                                 options.cipher = cipher_number(optarg);
 510                                 if (options.cipher == -1) {
 511                                         fprintf(stderr,
 512                                             "Unknown cipher type '%s'\n",
 513                                             optarg);
 514                                         exit(255);
 515                                 }
 516                                 if (options.cipher == SSH_CIPHER_3DES)
 517                                         options.ciphers = "3des-cbc";
 518                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 519                                         options.ciphers = "blowfish-cbc";
 520                                 else
 521                                         options.ciphers = (char *)-1;
 522                         }
 523                         break;
 524                 case 'm':
 525                         if (mac_valid(optarg))
 526                                 options.macs = xstrdup(optarg);
 527                         else {
 528                                 fprintf(stderr, "Unknown mac type '%s'\n",
 529                                     optarg);
 530                                 exit(255);
 531                         }
 532                         break;
 533                 case 'M':
 534                         if (options.control_master == SSHCTL_MASTER_YES)
 535                                 options.control_master = SSHCTL_MASTER_ASK;
 536                         else
 537                                 options.control_master = SSHCTL_MASTER_YES;
 538                         break;
 539                 case 'p':
 540                         options.port = a2port(optarg);
 541                         if (options.port <= 0) {
 542                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 543                                 exit(255);
 544                         }
 545                         break;
 546                 case 'l':
 547                         options.user = optarg;
 548                         break;
 549
 550                 case 'L':
 551                         if (parse_forward(&fwd, optarg, 0, 0))
 552                                 add_local_forward(&options, &fwd);
 553                         else {
 554                                 fprintf(stderr,
 555                                     "Bad local forwarding specification '%s'\n",
 556                                     optarg);
 557                                 exit(255);
 558                         }
 559                         break;
 560
 561                 case 'R':
 562                         if (parse_forward(&fwd, optarg, 0, 1)) {
 563                                 add_remote_forward(&options, &fwd);
 564                         } else {
 565                                 fprintf(stderr,
 566                                     "Bad remote forwarding specification "
 567                                     "'%s'\n", optarg);
 568                                 exit(255);
 569                         }
 570                         break;
 571
 572                 case 'D':
 573                         if (parse_forward(&fwd, optarg, 1, 0)) {
 574                                 add_local_forward(&options, &fwd);
 575                         } else {
 576                                 fprintf(stderr,
 577                                     "Bad dynamic forwarding specification "
 578                                     "'%s'\n", optarg);
 579                                 exit(255);
 580                         }
 581                         break;
 582
 583                 case 'C':
 584                         options.compression = 1;
 585                         break;
 586                 case 'N':
 587                         no_shell_flag = 1;
 588                         options.request_tty = REQUEST_TTY_NO;
 589                         break;
 590                 case 'T':
 591                         options.request_tty = REQUEST_TTY_NO;
 592 #ifdef  NONE_CIPHER_ENABLED
 593                         /*
 594                          * Ensure that the user does not try to backdoor a
 595                          * NONE cipher switch on an interactive session by
 596                          * explicitly disabling it if the user asks for a
 597                          * session without a tty.
 598                          */
 599                         options.none_switch = 0;
 600 #endif
 601                         break;
 602                 case 'o':
 603                         dummy = 1;
 604                         line = xstrdup(optarg);
 605                         if (process_config_line(&options, host ? host : "",
 606                             line, "command-line", 0, &dummy) != 0)
 607                                 exit(255);
 608                         xfree(line);
 609                         break;
 610                 case 's':
 611                         subsystem_flag = 1;
 612                         break;
 613                 case 'S':
 614                         if (options.control_path != NULL)
 615                                 free(options.control_path);
 616                         options.control_path = xstrdup(optarg);
 617                         break;
 618                 case 'b':
 619                         options.bind_address = optarg;
 620                         break;
 621                 case 'F':
 622                         config = optarg;
 623                         break;
 624                 default:
 625                         usage();
 626                 }
 627         }
 628
 629         ac -= optind;
 630         av += optind;
 631
 632         if (ac > 0 && !host) {
 633                 if (strrchr(*av, '@')) {
 634                         p = xstrdup(*av);
 635                         cp = strrchr(p, '@');
 636                         if (cp == NULL || cp == p)
 637                                 usage();
 638                         options.user = p;
 639                         *cp = '\0';
 640                         host = ++cp;
 641                 } else
 642                         host = *av;
 643                 if (ac > 1) {
 644                         optind = optreset = 1;
 645                         goto again;
 646                 }
 647                 ac--, av++;
 648         }
 649
 650         /* Check that we got a host name. */
 651         if (!host)
 652                 usage();
 653
 654         OpenSSL_add_all_algorithms();
 655         ERR_load_crypto_strings();
 656
 657         /* Initialize the command to execute on remote host. */
 658         buffer_init(&command);
 659
 660         /*
 661          * Save the command to execute on the remote host in a buffer. There
 662          * is no limit on the length of the command, except by the maximum
 663          * packet size.  Also sets the tty flag if there is no command.
 664          */
 665         if (!ac) {
 666                 /* No command specified - execute shell on a tty. */
 667                 if (subsystem_flag) {
 668                         fprintf(stderr,
 669                             "You must specify a subsystem to invoke.\n");
 670                         usage();
 671                 }
 672         } else {
 673                 /* A command has been specified.  Store it into the buffer. */
 674                 for (i = 0; i < ac; i++) {
 675                         if (i)
 676                                 buffer_append(&command, " ", 1);
 677                         buffer_append(&command, av[i], strlen(av[i]));
 678                 }
 679         }
 680
 681         /* Cannot fork to background if no command. */
 682         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 683             !no_shell_flag)
 684                 fatal("Cannot fork into background without a command "
 685                     "to execute.");
 686
 687         /*
 688          * Initialize "log" output.  Since we are the client all output
 689          * actually goes to stderr.
 690          */
 691         log_init(argv0,
 692             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 693             SYSLOG_FACILITY_USER, !use_syslog);
 694
 695         /*
 696          * Read per-user configuration file.  Ignore the system wide config
 697          * file if the user specifies a config file on the command line.
 698          */
 699         if (config != NULL) {
 700                 if (!read_config_file(config, host, &options, 0))
 701                         fatal("Can't open user config file %.100s: "
 702                             "%.100s", config, strerror(errno));
 703         } else {
 704                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 705                     _PATH_SSH_USER_CONFFILE);
 706                 if (r > 0 && (size_t)r < sizeof(buf))
 707                         (void)read_config_file(buf, host, &options, 1);
 708
 709                 /* Read systemwide configuration file after user config. */
 710                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 711                     &options, 0);
 712         }
 713
 714         /* Fill configuration defaults. */
 715         fill_default_options(&options);
 716
 717         channel_set_af(options.address_family);
 718
 719         /* reinit */
 720         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 721
 722         if (options.request_tty == REQUEST_TTY_YES ||
 723             options.request_tty == REQUEST_TTY_FORCE)
 724                 tty_flag = 1;
 725
 726         /* Allocate a tty by default if no command specified. */
 727         if (buffer_len(&command) == 0)
 728                 tty_flag = options.request_tty != REQUEST_TTY_NO;
 729
 730         /* Force no tty */
 731         if (options.request_tty == REQUEST_TTY_NO || muxclient_command != 0)
 732                 tty_flag = 0;
 733         /* Do not allocate a tty if stdin is not a tty. */
 734         if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
 735             options.request_tty != REQUEST_TTY_FORCE) {
 736                 if (tty_flag)
 737                         logit("Pseudo-terminal will not be allocated because "
 738                             "stdin is not a terminal.");
 739                 tty_flag = 0;
 740         }
 741
 742         seed_rng();
 743
 744         if (options.user == NULL)
 745                 options.user = xstrdup(pw->pw_name);
 746
 747         /* Get default port if port has not been set. */
 748         if (options.port == 0) {
 749                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 750                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 751         }
 752
 753         /* preserve host name given on command line for %n expansion */
 754         host_arg = host;
 755         if (options.hostname != NULL) {
 756                 host = percent_expand(options.hostname,
 757                     "h", host, (char *)NULL);
 758         }
 759
 760         if (gethostname(thishost, sizeof(thishost)) == -1)
 761                 fatal("gethostname: %s", strerror(errno));
 762         strlcpy(shorthost, thishost, sizeof(shorthost));
 763         shorthost[strcspn(thishost, ".")] = '\0';
 764         snprintf(portstr, sizeof(portstr), "%d", options.port);
 765
 766         if (options.local_command != NULL) {
 767                 debug3("expanding LocalCommand: %s", options.local_command);
 768                 cp = options.local_command;
 769                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 770                     "h", host, "l", thishost, "n", host_arg, "r", options.user,
 771                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 772                     (char *)NULL);
 773                 debug3("expanded LocalCommand: %s", options.local_command);
 774                 xfree(cp);
 775         }
 776
 777         /* Find canonic host name. */
 778         if (strchr(host, '.') == 0) {
 779                 struct addrinfo hints;
 780                 struct addrinfo *ai = NULL;
 781                 int errgai;
 782                 memset(&hints, 0, sizeof(hints));
 783                 hints.ai_family = options.address_family;
 784                 hints.ai_flags = AI_CANONNAME;
 785                 hints.ai_socktype = SOCK_STREAM;
 786                 errgai = getaddrinfo(host, NULL, &hints, &ai);
 787                 if (errgai == 0) {
 788                         if (ai->ai_canonname != NULL)
 789                                 host = xstrdup(ai->ai_canonname);
 790                         freeaddrinfo(ai);
 791                 }
 792         }
 793
 794         /* force lowercase for hostkey matching */
 795         if (options.host_key_alias != NULL) {
 796                 for (p = options.host_key_alias; *p; p++)
 797                         if (isupper(*p))
 798                                 *p = (char)tolower(*p);
 799         }
 800
 801         if (options.proxy_command != NULL &&
 802             strcmp(options.proxy_command, "none") == 0) {
 803                 xfree(options.proxy_command);
 804                 options.proxy_command = NULL;
 805         }
 806         if (options.control_path != NULL &&
 807             strcmp(options.control_path, "none") == 0) {
 808                 xfree(options.control_path);
 809                 options.control_path = NULL;
 810         }
 811
 812         if (options.control_path != NULL) {
 813                 cp = tilde_expand_filename(options.control_path,
 814                     original_real_uid);
 815                 xfree(options.control_path);
 816                 options.control_path = percent_expand(cp, "h", host,
 817                     "l", thishost, "n", host_arg, "r", options.user,
 818                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 819                     (char *)NULL);
 820                 xfree(cp);
 821         }
 822         if (muxclient_command != 0 && options.control_path == NULL)
 823                 fatal("No ControlPath specified for \"-O\" command");
 824         if (options.control_path != NULL)
 825                 muxclient(options.control_path);
 826
 827         timeout_ms = options.connection_timeout * 1000;
 828
 829         /* Open a connection to the remote host. */
 830         if (ssh_connect(host, &hostaddr, options.port,
 831             options.address_family, options.connection_attempts, &timeout_ms,
 832             options.tcp_keep_alive,
 833 #ifdef HAVE_CYGWIN
 834             options.use_privileged_port,
 835 #else
 836             original_effective_uid == 0 && options.use_privileged_port,
 837 #endif
 838             options.proxy_command) != 0)
 839                 exit(255);
 840
 841         if (timeout_ms > 0)
 842                 debug3("timeout: %d ms remain after connect", timeout_ms);
 843
 844         /*
 845          * If we successfully made the connection, load the host private key
 846          * in case we will need it later for combined rsa-rhosts
 847          * authentication. This must be done before releasing extra
 848          * privileges, because the file is only readable by root.
 849          * If we cannot access the private keys, load the public keys
 850          * instead and try to execute the ssh-keysign helper instead.
 851          */
 852         sensitive_data.nkeys = 0;
 853         sensitive_data.keys = NULL;
 854         sensitive_data.external_keysign = 0;
 855         if (options.rhosts_rsa_authentication ||
 856             options.hostbased_authentication) {
 857                 sensitive_data.nkeys = 7;
 858                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 859                     sizeof(Key));
 860                 for (i = 0; i < sensitive_data.nkeys; i++)
 861                         sensitive_data.keys[i] = NULL;
 862
 863                 PRIV_START;
 864                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 865                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 866                 sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
 867                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 868 #ifdef OPENSSL_HAS_ECC
 869                 sensitive_data.keys[2] = key_load_private_cert(KEY_ECDSA,
 870                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
 871 #endif
 872                 sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
 873                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 874                 sensitive_data.keys[4] = key_load_private_type(KEY_DSA,
 875                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 876 #ifdef OPENSSL_HAS_ECC
 877                 sensitive_data.keys[5] = key_load_private_type(KEY_ECDSA,
 878                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
 879 #endif
 880                 sensitive_data.keys[6] = key_load_private_type(KEY_RSA,
 881                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 882                 PRIV_END;
 883
 884                 if (options.hostbased_authentication == 1 &&
 885                     sensitive_data.keys[0] == NULL &&
 886                     sensitive_data.keys[4] == NULL &&
 887                     sensitive_data.keys[5] == NULL &&
 888                     sensitive_data.keys[6] == NULL) {
 889                         sensitive_data.keys[1] = key_load_cert(
 890                             _PATH_HOST_DSA_KEY_FILE);
 891 #ifdef OPENSSL_HAS_ECC
 892                         sensitive_data.keys[2] = key_load_cert(
 893                             _PATH_HOST_ECDSA_KEY_FILE);
 894 #endif
 895                         sensitive_data.keys[3] = key_load_cert(
 896                             _PATH_HOST_RSA_KEY_FILE);
 897                         sensitive_data.keys[4] = key_load_public(
 898                             _PATH_HOST_DSA_KEY_FILE, NULL);
 899 #ifdef OPENSSL_HAS_ECC
 900                         sensitive_data.keys[5] = key_load_public(
 901                             _PATH_HOST_ECDSA_KEY_FILE, NULL);
 902 #endif
 903                         sensitive_data.keys[6] = key_load_public(
 904                             _PATH_HOST_RSA_KEY_FILE, NULL);
 905                         sensitive_data.external_keysign = 1;
 906                 }
 907         }
 908         /*
 909          * Get rid of any extra privileges that we may have.  We will no
 910          * longer need them.  Also, extra privileges could make it very hard
 911          * to read identity files and other non-world-readable files from the
 912          * user's home directory if it happens to be on a NFS volume where
 913          * root is mapped to nobody.
 914          */
 915         if (original_effective_uid == 0) {
 916                 PRIV_START;
 917                 permanently_set_uid(pw);
 918         }
 919
 920         /*
 921          * Now that we are back to our own permissions, create ~/.ssh
 922          * directory if it doesn't already exist.
 923          */
 924         if (config == NULL) {
 925                 r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
 926                     strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 927                 if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
 928 #ifdef WITH_SELINUX
 929                         ssh_selinux_setfscreatecon(buf);
 930 #endif
 931                         if (mkdir(buf, 0700) < 0)
 932                                 error("Could not create directory '%.200s'.",
 933                                     buf);
 934 #ifdef WITH_SELINUX
 935                         ssh_selinux_setfscreatecon(NULL);
 936 #endif
 937                 }
 938         }
 939         /* load options.identity_files */
 940         load_public_identity_files();
 941
 942         /* Expand ~ in known host file names. */
 943         tilde_expand_paths(options.system_hostfiles,
 944             options.num_system_hostfiles);
 945         tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
 946
 947         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 948         signal(SIGCHLD, main_sigchld_handler);
 949
 950         /* Log into the remote system.  Never returns if the login fails. */
 951         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 952             options.port, pw, timeout_ms);
 953
 954         if (packet_connection_is_on_socket()) {
 955                 verbose("Authenticated to %s ([%s]:%d).", host,
 956                     get_remote_ipaddr(), get_remote_port());
 957         } else {
 958                 verbose("Authenticated to %s (via proxy).", host);
 959         }
 960
 961         /* We no longer need the private host keys.  Clear them now. */
 962         if (sensitive_data.nkeys != 0) {
 963                 for (i = 0; i < sensitive_data.nkeys; i++) {
 964                         if (sensitive_data.keys[i] != NULL) {
 965                                 /* Destroys contents safely */
 966                                 debug3("clear hostkey %d", i);
 967                                 key_free(sensitive_data.keys[i]);
 968                                 sensitive_data.keys[i] = NULL;
 969                         }
 970                 }
 971                 xfree(sensitive_data.keys);
 972         }
 973         for (i = 0; i < options.num_identity_files; i++) {
 974                 if (options.identity_files[i]) {
 975                         xfree(options.identity_files[i]);
 976                         options.identity_files[i] = NULL;
 977                 }
 978                 if (options.identity_keys[i]) {
 979                         key_free(options.identity_keys[i]);
 980                         options.identity_keys[i] = NULL;
 981                 }
 982         }
 983
 984         exit_status = compat20 ? ssh_session2() : ssh_session();
 985         packet_close();
 986
 987         if (options.control_path != NULL && muxserver_sock != -1)
 988                 unlink(options.control_path);
 989
 990         /* Kill ProxyCommand if it is running. */
 991         ssh_kill_proxy_command();
 992
 993         return exit_status;
 994 }
 995
 996 static void
 997 control_persist_detach(void)
 998 {
 999         pid_t pid;
1000         int devnull;
1001
1002         debug("%s: backgrounding master process", __func__);
1003
1004         /*
1005          * master (current process) into the background, and make the
1006          * foreground process a client of the backgrounded master.
1007          */
1008         switch ((pid = fork())) {
1009         case -1:
1010                 fatal("%s: fork: %s", __func__, strerror(errno));
1011         case 0:
1012                 /* Child: master process continues mainloop */
1013                 break;
1014         default:
1015                 /* Parent: set up mux slave to connect to backgrounded master */
1016                 debug2("%s: background process is %ld", __func__, (long)pid);
1017                 stdin_null_flag = ostdin_null_flag;
1018                 options.request_tty = orequest_tty;
1019                 tty_flag = otty_flag;
1020                 close(muxserver_sock);
1021                 muxserver_sock = -1;
1022                 options.control_master = SSHCTL_MASTER_NO;
1023                 muxclient(options.control_path);
1024                 /* muxclient() doesn't return on success. */
1025                 fatal("Failed to connect to new control master");
1026         }
1027         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1028                 error("%s: open(\"/dev/null\"): %s", __func__,
1029                     strerror(errno));
1030         } else {
1031                 if (dup2(devnull, STDIN_FILENO) == -1 ||
1032                     dup2(devnull, STDOUT_FILENO) == -1)
1033                         error("%s: dup2: %s", __func__, strerror(errno));
1034                 if (devnull > STDERR_FILENO)
1035                         close(devnull);
1036         }
1037         setproctitle("%s [mux]", options.control_path);
1038 }
1039
1040 /* Do fork() after authentication. Used by "ssh -f" */
1041 static void
1042 fork_postauth(void)
1043 {
1044         if (need_controlpersist_detach)
1045                 control_persist_detach();
1046         debug("forking to background");
1047         fork_after_authentication_flag = 0;
1048         if (daemon(1, 1) < 0)
1049                 fatal("daemon() failed: %.200s", strerror(errno));
1050 }
1051
1052 /* Callback for remote forward global requests */
1053 static void
1054 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
1055 {
1056         Forward *rfwd = (Forward *)ctxt;
1057
1058         /* XXX verbose() on failure? */
1059         debug("remote forward %s for: listen %d, connect %s:%d",
1060             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1061             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
1062         if (rfwd->listen_port == 0) {
1063                 if (type == SSH2_MSG_REQUEST_SUCCESS) {
1064                         rfwd->allocated_port = packet_get_int();
1065                         logit("Allocated port %u for remote forward to %s:%d",
1066                             rfwd->allocated_port,
1067                             rfwd->connect_host, rfwd->connect_port);
1068                         channel_update_permitted_opens(rfwd->handle,
1069                             rfwd->allocated_port);
1070                 } else {
1071                         channel_update_permitted_opens(rfwd->handle, -1);
1072                 }
1073         }
1074
1075         if (type == SSH2_MSG_REQUEST_FAILURE) {
1076                 if (options.exit_on_forward_failure)
1077                         fatal("Error: remote port forwarding failed for "
1078                             "listen port %d", rfwd->listen_port);
1079                 else
1080                         logit("Warning: remote port forwarding failed for "
1081                             "listen port %d", rfwd->listen_port);
1082         }
1083         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1084                 debug("All remote forwarding requests processed");
1085                 if (fork_after_authentication_flag)
1086                         fork_postauth();
1087         }
1088 }
1089
1090 static void
1091 client_cleanup_stdio_fwd(int id, void *arg)
1092 {
1093         debug("stdio forwarding: done");
1094         cleanup_exit(0);
1095 }
1096
1097 static void
1098 ssh_init_stdio_forwarding(void)
1099 {
1100         Channel *c;
1101         int in, out;
1102
1103         if (stdio_forward_host == NULL)
1104                 return;
1105         if (!compat20)
1106                 fatal("stdio forwarding require Protocol 2");
1107
1108         debug3("%s: %s:%d", __func__, stdio_forward_host, stdio_forward_port);
1109
1110         if ((in = dup(STDIN_FILENO)) < 0 ||
1111             (out = dup(STDOUT_FILENO)) < 0)
1112                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1113         if ((c = channel_connect_stdio_fwd(stdio_forward_host,
1114             stdio_forward_port, in, out)) == NULL)
1115                 fatal("%s: channel_connect_stdio_fwd failed", __func__);
1116         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1117 }
1118
1119 static void
1120 ssh_init_forwarding(void)
1121 {
1122         int success = 0;
1123         int i;
1124
1125         /* Initiate local TCP/IP port forwardings. */
1126         for (i = 0; i < options.num_local_forwards; i++) {
1127                 debug("Local connections to %.200s:%d forwarded to remote "
1128                     "address %.200s:%d",
1129                     (options.local_forwards[i].listen_host == NULL) ?
1130                     (options.gateway_ports ? "*" : "LOCALHOST") :
1131                     options.local_forwards[i].listen_host,
1132                     options.local_forwards[i].listen_port,
1133                     options.local_forwards[i].connect_host,
1134                     options.local_forwards[i].connect_port);
1135                 success += channel_setup_local_fwd_listener(
1136                     options.local_forwards[i].listen_host,
1137                     options.local_forwards[i].listen_port,
1138                     options.local_forwards[i].connect_host,
1139                     options.local_forwards[i].connect_port,
1140                     options.gateway_ports);
1141         }
1142         if (i > 0 && success != i && options.exit_on_forward_failure)
1143                 fatal("Could not request local forwarding.");
1144         if (i > 0 && success == 0)
1145                 error("Could not request local forwarding.");
1146
1147         /* Initiate remote TCP/IP port forwardings. */
1148         for (i = 0; i < options.num_remote_forwards; i++) {
1149                 debug("Remote connections from %.200s:%d forwarded to "
1150                     "local address %.200s:%d",
1151                     (options.remote_forwards[i].listen_host == NULL) ?
1152                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1153                     options.remote_forwards[i].listen_port,
1154                     options.remote_forwards[i].connect_host,
1155                     options.remote_forwards[i].connect_port);
1156                 options.remote_forwards[i].handle =
1157                     channel_request_remote_forwarding(
1158                     options.remote_forwards[i].listen_host,
1159                     options.remote_forwards[i].listen_port,
1160                     options.remote_forwards[i].connect_host,
1161                     options.remote_forwards[i].connect_port);
1162                 if (options.remote_forwards[i].handle < 0) {
1163                         if (options.exit_on_forward_failure)
1164                                 fatal("Could not request remote forwarding.");
1165                         else
1166                                 logit("Warning: Could not request remote "
1167                                     "forwarding.");
1168                 } else {
1169                         client_register_global_confirm(ssh_confirm_remote_forward,
1170                             &options.remote_forwards[i]);
1171                 }
1172         }
1173
1174         /* Initiate tunnel forwarding. */
1175         if (options.tun_open != SSH_TUNMODE_NO) {
1176                 if (client_request_tun_fwd(options.tun_open,
1177                     options.tun_local, options.tun_remote) == -1) {
1178                         if (options.exit_on_forward_failure)
1179                                 fatal("Could not request tunnel forwarding.");
1180                         else
1181                                 error("Could not request tunnel forwarding.");
1182                 }
1183         }
1184 }
1185
1186 static void
1187 check_agent_present(void)
1188 {
1189         if (options.forward_agent) {
1190                 /* Clear agent forwarding if we don't have an agent. */
1191                 if (!ssh_agent_present())
1192                         options.forward_agent = 0;
1193         }
1194 }
1195
1196 static int
1197 ssh_session(void)
1198 {
1199         int type;
1200         int interactive = 0;
1201         int have_tty = 0;
1202         struct winsize ws;
1203         char *cp;
1204         const char *display;
1205
1206         /* Enable compression if requested. */
1207         if (options.compression) {
1208                 debug("Requesting compression at level %d.",
1209                     options.compression_level);
1210
1211                 if (options.compression_level < 1 ||
1212                     options.compression_level > 9)
1213                         fatal("Compression level must be from 1 (fast) to "
1214                             "9 (slow, best).");
1215
1216                 /* Send the request. */
1217                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1218                 packet_put_int(options.compression_level);
1219                 packet_send();
1220                 packet_write_wait();
1221                 type = packet_read();
1222                 if (type == SSH_SMSG_SUCCESS)
1223                         packet_start_compression(options.compression_level);
1224                 else if (type == SSH_SMSG_FAILURE)
1225                         logit("Warning: Remote host refused compression.");
1226                 else
1227                         packet_disconnect("Protocol error waiting for "
1228                             "compression response.");
1229         }
1230         /* Allocate a pseudo tty if appropriate. */
1231         if (tty_flag) {
1232                 debug("Requesting pty.");
1233
1234                 /* Start the packet. */
1235                 packet_start(SSH_CMSG_REQUEST_PTY);
1236
1237                 /* Store TERM in the packet.  There is no limit on the
1238                    length of the string. */
1239                 cp = getenv("TERM");
1240                 if (!cp)
1241                         cp = "";
1242                 packet_put_cstring(cp);
1243
1244                 /* Store window size in the packet. */
1245                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1246                         memset(&ws, 0, sizeof(ws));
1247                 packet_put_int((u_int)ws.ws_row);
1248                 packet_put_int((u_int)ws.ws_col);
1249                 packet_put_int((u_int)ws.ws_xpixel);
1250                 packet_put_int((u_int)ws.ws_ypixel);
1251
1252                 /* Store tty modes in the packet. */
1253                 tty_make_modes(fileno(stdin), NULL);
1254
1255                 /* Send the packet, and wait for it to leave. */
1256                 packet_send();
1257                 packet_write_wait();
1258
1259                 /* Read response from the server. */
1260                 type = packet_read();
1261                 if (type == SSH_SMSG_SUCCESS) {
1262                         interactive = 1;
1263                         have_tty = 1;
1264                 } else if (type == SSH_SMSG_FAILURE)
1265                         logit("Warning: Remote host failed or refused to "
1266                             "allocate a pseudo tty.");
1267                 else
1268                         packet_disconnect("Protocol error waiting for pty "
1269                             "request response.");
1270         }
1271         /* Request X11 forwarding if enabled and DISPLAY is set. */
1272         display = getenv("DISPLAY");
1273         if (options.forward_x11 && display != NULL) {
1274                 char *proto, *data;
1275                 /* Get reasonable local authentication information. */
1276                 client_x11_get_proto(display, options.xauth_location,
1277                     options.forward_x11_trusted,
1278                     options.forward_x11_timeout,
1279                     &proto, &data);
1280                 /* Request forwarding with authentication spoofing. */
1281                 debug("Requesting X11 forwarding with authentication "
1282                     "spoofing.");
1283                 x11_request_forwarding_with_spoofing(0, display, proto,
1284                     data, 0);
1285                 /* Read response from the server. */
1286                 type = packet_read();
1287                 if (type == SSH_SMSG_SUCCESS) {
1288                         interactive = 1;
1289                 } else if (type == SSH_SMSG_FAILURE) {
1290                         logit("Warning: Remote host denied X11 forwarding.");
1291                 } else {
1292                         packet_disconnect("Protocol error waiting for X11 "
1293                             "forwarding");
1294                 }
1295         }
1296         /* Tell the packet module whether this is an interactive session. */
1297         packet_set_interactive(interactive,
1298             options.ip_qos_interactive, options.ip_qos_bulk);
1299
1300         /* Request authentication agent forwarding if appropriate. */
1301         check_agent_present();
1302
1303         if (options.forward_agent) {
1304                 debug("Requesting authentication agent forwarding.");
1305                 auth_request_forwarding();
1306
1307                 /* Read response from the server. */
1308                 type = packet_read();
1309                 packet_check_eom();
1310                 if (type != SSH_SMSG_SUCCESS)
1311                         logit("Warning: Remote host denied authentication agent forwarding.");
1312         }
1313
1314         /* Initiate port forwardings. */
1315         ssh_init_stdio_forwarding();
1316         ssh_init_forwarding();
1317
1318         /* Execute a local command */
1319         if (options.local_command != NULL &&
1320             options.permit_local_command)
1321                 ssh_local_cmd(options.local_command);
1322
1323         /*
1324          * If requested and we are not interested in replies to remote
1325          * forwarding requests, then let ssh continue in the background.
1326          */
1327         if (fork_after_authentication_flag) {
1328                 if (options.exit_on_forward_failure &&
1329                     options.num_remote_forwards > 0) {
1330                         debug("deferring postauth fork until remote forward "
1331                             "confirmation received");
1332                 } else
1333                         fork_postauth();
1334         }
1335
1336         /*
1337          * If a command was specified on the command line, execute the
1338          * command now. Otherwise request the server to start a shell.
1339          */
1340         if (buffer_len(&command) > 0) {
1341                 int len = buffer_len(&command);
1342                 if (len > 900)
1343                         len = 900;
1344                 debug("Sending command: %.*s", len,
1345                     (u_char *)buffer_ptr(&command));
1346                 packet_start(SSH_CMSG_EXEC_CMD);
1347                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1348                 packet_send();
1349                 packet_write_wait();
1350         } else {
1351                 debug("Requesting shell.");
1352                 packet_start(SSH_CMSG_EXEC_SHELL);
1353                 packet_send();
1354                 packet_write_wait();
1355         }
1356
1357         /* Enter the interactive session. */
1358         return client_loop(have_tty, tty_flag ?
1359             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1360 }
1361
1362 /* request pty/x11/agent/tcpfwd/shell for channel */
1363 static void
1364 ssh_session2_setup(int id, int success, void *arg)
1365 {
1366         extern char **environ;
1367         const char *display;
1368         int interactive = tty_flag;
1369
1370         if (!success)
1371                 return; /* No need for error message, channels code sens one */
1372
1373         display = getenv("DISPLAY");
1374         if (options.forward_x11 && display != NULL) {
1375                 char *proto, *data;
1376                 /* Get reasonable local authentication information. */
1377                 client_x11_get_proto(display, options.xauth_location,
1378                     options.forward_x11_trusted,
1379                     options.forward_x11_timeout, &proto, &data);
1380                 /* Request forwarding with authentication spoofing. */
1381                 debug("Requesting X11 forwarding with authentication "
1382                     "spoofing.");
1383                 x11_request_forwarding_with_spoofing(id, display, proto,
1384                     data, 1);
1385                 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
1386                 /* XXX exit_on_forward_failure */
1387                 interactive = 1;
1388         }
1389
1390         check_agent_present();
1391         if (options.forward_agent) {
1392                 debug("Requesting authentication agent forwarding.");
1393                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1394                 packet_send();
1395         }
1396
1397         /* Tell the packet module whether this is an interactive session. */
1398         packet_set_interactive(interactive,
1399             options.ip_qos_interactive, options.ip_qos_bulk);
1400
1401         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1402             NULL, fileno(stdin), &command, environ);
1403 }
1404
1405 /* open new channel for a session */
1406 static int
1407 ssh_session2_open(void)
1408 {
1409         Channel *c;
1410         int window, packetmax, in, out, err;
1411
1412         if (stdin_null_flag) {
1413                 in = open(_PATH_DEVNULL, O_RDONLY);
1414         } else {
1415                 in = dup(STDIN_FILENO);
1416         }
1417         out = dup(STDOUT_FILENO);
1418         err = dup(STDERR_FILENO);
1419
1420         if (in < 0 || out < 0 || err < 0)
1421                 fatal("dup() in/out/err failed");
1422
1423         /* enable nonblocking unless tty */
1424         if (!isatty(in))
1425                 set_nonblock(in);
1426         if (!isatty(out))
1427                 set_nonblock(out);
1428         if (!isatty(err))
1429                 set_nonblock(err);
1430
1431         /*
1432          * We need to check to see what to do about buffer sizes here.
1433          * - In an HPN to non-HPN connection we want to limit the window size to
1434          *   something reasonable in case the far side has the large window bug.
1435          * - In an HPN to HPN connection we want to use the max window size but
1436          *   allow the user to override it.
1437          * - Lastly if HPN is disabled then use the ssh standard window size.
1438          *
1439          * We cannot just do a getsockopt() here and set the ssh window to that
1440          * as in case of autotuning of socket buffers the window would get stuck
1441          * at the initial buffer size, generally less than 96k.  Therefore we
1442          * need to set the maximum ssh window size to the maximum HPN buffer
1443          * size unless the user has set TcpRcvBufPoll to no.  In that case we
1444          * can just set the window to the minimum of HPN buffer size and TCP
1445          * receive buffer size.
1446          */
1447         if (tty_flag)
1448                 options.hpn_buffer_size = CHAN_SES_WINDOW_DEFAULT;
1449         else
1450                 options.hpn_buffer_size = CHAN_HPN_MIN_WINDOW_DEFAULT;
1451
1452         if (datafellows & SSH_BUG_LARGEWINDOW) {
1453                 debug("HPN to Non-HPN Connection");
1454         } else if (options.tcp_rcv_buf_poll <= 0) {
1455                 sock_get_rcvbuf(&options.hpn_buffer_size, 0);
1456                 debug("HPNBufferSize set to TCP RWIN: %d",
1457                     options.hpn_buffer_size);
1458         } else if (options.tcp_rcv_buf > 0) {
1459                 sock_get_rcvbuf(&options.hpn_buffer_size,
1460                     options.tcp_rcv_buf);
1461                 debug("HPNBufferSize set to user TCPRcvBuf: %d",
1462                     options.hpn_buffer_size);
1463         }
1464         debug("Final hpn_buffer_size = %d", options.hpn_buffer_size);
1465         channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1466         window = options.hpn_buffer_size;
1467
1468         packetmax = CHAN_SES_PACKET_DEFAULT;
1469         if (tty_flag) {
1470                 window = CHAN_SES_WINDOW_DEFAULT;
1471                 window >>= 1;
1472                 packetmax >>= 1;
1473         }
1474         c = channel_new(
1475             "session", SSH_CHANNEL_OPENING, in, out, err,
1476             window, packetmax, CHAN_EXTENDED_WRITE,
1477             "client-session", /*nonblock*/0);
1478         if (!options.hpn_disabled && options.tcp_rcv_buf_poll > 0) {
1479                 c->dynamic_window = 1;
1480                 debug("Enabled Dynamic Window Scaling\n");
1481         }
1482
1483         debug3("ssh_session2_open: channel_new: %d", c->self);
1484
1485         channel_send_open(c->self);
1486         if (!no_shell_flag)
1487                 channel_register_open_confirm(c->self,
1488                     ssh_session2_setup, NULL);
1489
1490         return c->self;
1491 }
1492
1493 static int
1494 ssh_session2(void)
1495 {
1496         int id = -1;
1497
1498         /* XXX should be pre-session */
1499         if (!options.control_persist)
1500                 ssh_init_stdio_forwarding();
1501         ssh_init_forwarding();
1502
1503         /* Start listening for multiplex clients */
1504         muxserver_listen();
1505
1506         /*
1507          * If we are in control persist mode and have a working mux listen
1508          * socket, then prepare to background ourselves and have a foreground
1509          * client attach as a control slave.
1510          * NB. we must save copies of the flags that we override for
1511          * the backgrounding, since we defer attachment of the slave until
1512          * after the connection is fully established (in particular,
1513          * async rfwd replies have been received for ExitOnForwardFailure).
1514          */
1515         if (options.control_persist && muxserver_sock != -1) {
1516                 ostdin_null_flag = stdin_null_flag;
1517                 ono_shell_flag = no_shell_flag;
1518                 orequest_tty = options.request_tty;
1519                 otty_flag = tty_flag;
1520                 stdin_null_flag = 1;
1521                 no_shell_flag = 1;
1522                 tty_flag = 0;
1523                 if (!fork_after_authentication_flag)
1524                         need_controlpersist_detach = 1;
1525                 fork_after_authentication_flag = 1;
1526         }
1527         /*
1528          * ControlPersist mux listen socket setup failed, attempt the
1529          * stdio forward setup that we skipped earlier.
1530          */
1531         if (options.control_persist && muxserver_sock == -1)
1532                 ssh_init_stdio_forwarding();
1533
1534         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1535                 id = ssh_session2_open();
1536
1537         /* If we don't expect to open a new session, then disallow it */
1538         if (options.control_master == SSHCTL_MASTER_NO &&
1539             (datafellows & SSH_NEW_OPENSSH)) {
1540                 debug("Requesting no-more-sessions@openssh.com");
1541                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1542                 packet_put_cstring("no-more-sessions@openssh.com");
1543                 packet_put_char(0);
1544                 packet_send();
1545         }
1546
1547         /* Execute a local command */
1548         if (options.local_command != NULL &&
1549             options.permit_local_command)
1550                 ssh_local_cmd(options.local_command);
1551
1552         /*
1553          * If requested and we are not interested in replies to remote
1554          * forwarding requests, then let ssh continue in the background.
1555          */
1556         if (fork_after_authentication_flag) {
1557                 if (options.exit_on_forward_failure &&
1558                     options.num_remote_forwards > 0) {
1559                         debug("deferring postauth fork until remote forward "
1560                             "confirmation received");
1561                 } else
1562                         fork_postauth();
1563         }
1564
1565         if (options.use_roaming)
1566                 request_roaming();
1567
1568         return client_loop(tty_flag, tty_flag ?
1569             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1570 }
1571
1572 static void
1573 load_public_identity_files(void)
1574 {
1575         char *filename, *cp, thishost[NI_MAXHOST];
1576         char *pwdir = NULL, *pwname = NULL;
1577         int i = 0;
1578         Key *public;
1579         struct passwd *pw;
1580         u_int n_ids;
1581         char *identity_files[SSH_MAX_IDENTITY_FILES];
1582         Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1583 #ifdef ENABLE_PKCS11
1584         Key **keys;
1585         int nkeys;
1586 #endif /* PKCS11 */
1587
1588         n_ids = 0;
1589         bzero(identity_files, sizeof(identity_files));
1590         bzero(identity_keys, sizeof(identity_keys));
1591
1592 #ifdef ENABLE_PKCS11
1593         if (options.pkcs11_provider != NULL &&
1594             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1595             (pkcs11_init(!options.batch_mode) == 0) &&
1596             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1597             &keys)) > 0) {
1598                 for (i = 0; i < nkeys; i++) {
1599                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1600                                 key_free(keys[i]);
1601                                 continue;
1602                         }
1603                         identity_keys[n_ids] = keys[i];
1604                         identity_files[n_ids] =
1605                             xstrdup(options.pkcs11_provider); /* XXX */
1606                         n_ids++;
1607                 }
1608                 xfree(keys);
1609         }
1610 #endif /* ENABLE_PKCS11 */
1611         if ((pw = getpwuid(original_real_uid)) == NULL)
1612                 fatal("load_public_identity_files: getpwuid failed");
1613         pwname = xstrdup(pw->pw_name);
1614         pwdir = xstrdup(pw->pw_dir);
1615         if (gethostname(thishost, sizeof(thishost)) == -1)
1616                 fatal("load_public_identity_files: gethostname: %s",
1617                     strerror(errno));
1618         for (i = 0; i < options.num_identity_files; i++) {
1619                 if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1620                         xfree(options.identity_files[i]);
1621                         continue;
1622                 }
1623                 cp = tilde_expand_filename(options.identity_files[i],
1624                     original_real_uid);
1625                 filename = percent_expand(cp, "d", pwdir,
1626                     "u", pwname, "l", thishost, "h", host,
1627                     "r", options.user, (char *)NULL);
1628                 xfree(cp);
1629                 public = key_load_public(filename, NULL);
1630                 debug("identity file %s type %d", filename,
1631                     public ? public->type : -1);
1632                 xfree(options.identity_files[i]);
1633                 identity_files[n_ids] = filename;
1634                 identity_keys[n_ids] = public;
1635
1636                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
1637                         continue;
1638
1639                 /* Try to add the certificate variant too */
1640                 xasprintf(&cp, "%s-cert", filename);
1641                 public = key_load_public(cp, NULL);
1642                 debug("identity file %s type %d", cp,
1643                     public ? public->type : -1);
1644                 if (public == NULL) {
1645                         xfree(cp);
1646                         continue;
1647                 }
1648                 if (!key_is_cert(public)) {
1649                         debug("%s: key %s type %s is not a certificate",
1650                             __func__, cp, key_type(public));
1651                         key_free(public);
1652                         xfree(cp);
1653                         continue;
1654                 }
1655                 identity_keys[n_ids] = public;
1656                 /* point to the original path, most likely the private key */
1657                 identity_files[n_ids] = xstrdup(filename);
1658                 n_ids++;
1659         }
1660         options.num_identity_files = n_ids;
1661         memcpy(options.identity_files, identity_files, sizeof(identity_files));
1662         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
1663
1664         bzero(pwname, strlen(pwname));
1665         xfree(pwname);
1666         bzero(pwdir, strlen(pwdir));
1667         xfree(pwdir);
1668 }
1669
1670 static void
1671 main_sigchld_handler(int sig)
1672 {
1673         int save_errno = errno;
1674         pid_t pid;
1675         int status;
1676
1677         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
1678             (pid < 0 && errno == EINTR))
1679                 ;
1680
1681         signal(sig, main_sigchld_handler);
1682         errno = save_errno;
1683 }
1684