ssh.c

   1 /* $OpenBSD: ssh.c,v 1.370 2012/07/06 01:47:38 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * Ssh client program.  This program can be used to log into a remote machine.
   7  * The software supports strong authentication, encryption, and forwarding
   8  * of X11, TCP/IP, and authentication connections.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  17  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  18  *
  19  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  20  * in Canada (German citizen).
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the above copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  *
  31  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  32  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  34  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  35  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  36  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  37  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  38  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  39  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  40  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  41  */
  42
  43 #include "includes.h"
  44
  45 #include <sys/types.h>
  46 #ifdef HAVE_SYS_STAT_H
  47 # include <sys/stat.h>
  48 #endif
  49 #include <sys/resource.h>
  50 #include <sys/ioctl.h>
  51 #include <sys/param.h>
  52 #include <sys/socket.h>
  53 #include <sys/wait.h>
  54
  55 #include <ctype.h>
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #include <netdb.h>
  59 #ifdef HAVE_PATHS_H
  60 #include <paths.h>
  61 #endif
  62 #include <pwd.h>
  63 #include <signal.h>
  64 #include <stdarg.h>
  65 #include <stddef.h>
  66 #include <stdio.h>
  67 #include <stdlib.h>
  68 #include <string.h>
  69 #include <unistd.h>
  70
  71 #include <netinet/in.h>
  72 #include <arpa/inet.h>
  73
  74 #include <openssl/evp.h>
  75 #include <openssl/err.h>
  76 #include "openbsd-compat/openssl-compat.h"
  77 #include "openbsd-compat/sys-queue.h"
  78
  79 #include "xmalloc.h"
  80 #include "ssh.h"
  81 #include "ssh1.h"
  82 #include "ssh2.h"
  83 #include "canohost.h"
  84 #include "compat.h"
  85 #include "cipher.h"
  86 #include "packet.h"
  87 #include "buffer.h"
  88 #include "channels.h"
  89 #include "key.h"
  90 #include "authfd.h"
  91 #include "authfile.h"
  92 #include "pathnames.h"
  93 #include "dispatch.h"
  94 #include "clientloop.h"
  95 #include "log.h"
  96 #include "readconf.h"
  97 #include "sshconnect.h"
  98 #include "misc.h"
  99 #include "kex.h"
 100 #include "mac.h"
 101 #include "sshpty.h"
 102 #include "match.h"
 103 #include "msg.h"
 104 #include "uidswap.h"
 105 #include "roaming.h"
 106 #include "version.h"
 107
 108 #ifdef ENABLE_PKCS11
 109 #include "ssh-pkcs11.h"
 110 #endif
 111
 112 extern char *__progname;
 113
 114 /* Saves a copy of argv for setproctitle emulation */
 115 #ifndef HAVE_SETPROCTITLE
 116 static char **saved_av;
 117 #endif
 118
 119 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 120 int debug_flag = 0;
 121
 122 /* Flag indicating whether a tty should be requested */
 123 int tty_flag = 0;
 124
 125 /* don't exec a shell */
 126 int no_shell_flag = 0;
 127
 128 /*
 129  * Flag indicating that nothing should be read from stdin.  This can be set
 130  * on the command line.
 131  */
 132 int stdin_null_flag = 0;
 133
 134 /*
 135  * Flag indicating that the current process should be backgrounded and
 136  * a new slave launched in the foreground for ControlPersist.
 137  */
 138 int need_controlpersist_detach = 0;
 139
 140 /* Copies of flags for ControlPersist foreground slave */
 141 int ostdin_null_flag, ono_shell_flag, otty_flag, orequest_tty;
 142
 143 /*
 144  * Flag indicating that ssh should fork after authentication.  This is useful
 145  * so that the passphrase can be entered manually, and then ssh goes to the
 146  * background.
 147  */
 148 int fork_after_authentication_flag = 0;
 149
 150 /* forward stdio to remote host and port */
 151 char *stdio_forward_host = NULL;
 152 int stdio_forward_port = 0;
 153
 154 /*
 155  * General data structure for command line options and options configurable
 156  * in configuration files.  See readconf.h.
 157  */
 158 Options options;
 159
 160 /* optional user configfile */
 161 char *config = NULL;
 162
 163 /*
 164  * Name of the host we are connecting to.  This is the name given on the
 165  * command line, or the HostName specified for the user-supplied name in a
 166  * configuration file.
 167  */
 168 char *host;
 169
 170 /* socket address the host resolves to */
 171 struct sockaddr_storage hostaddr;
 172
 173 /* Private host keys. */
 174 Sensitive sensitive_data;
 175
 176 /* Original real UID. */
 177 uid_t original_real_uid;
 178 uid_t original_effective_uid;
 179
 180 /* command to be executed */
 181 Buffer command;
 182
 183 /* Should we execute a command or invoke a subsystem? */
 184 int subsystem_flag = 0;
 185
 186 /* # of replies received for global requests */
 187 static int remote_forward_confirms_received = 0;
 188
 189 /* mux.c */
 190 extern int muxserver_sock;
 191 extern u_int muxclient_command;
 192
 193 /* Prints a help message to the user.  This function never returns. */
 194
 195 static void
 196 usage(void)
 197 {
 198         fprintf(stderr,
 199 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
 200 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 201 "           [-I pkcs11] [-i identity_file]\n"
 202 "           [-L [bind_address:]port:host:hostport]\n"
 203 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 204 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 205 "           [-W host:port] [-w local_tun[:remote_tun]]\n"
 206 "           [user@]hostname [command]\n"
 207         );
 208         exit(255);
 209 }
 210
 211 static int ssh_session(void);
 212 static int ssh_session2(void);
 213 static void load_public_identity_files(void);
 214 static void main_sigchld_handler(int);
 215
 216 /* from muxclient.c */
 217 void muxclient(const char *);
 218 void muxserver_listen(void);
 219
 220 /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
 221 static void
 222 tilde_expand_paths(char **paths, u_int num_paths)
 223 {
 224         u_int i;
 225         char *cp;
 226
 227         for (i = 0; i < num_paths; i++) {
 228                 cp = tilde_expand_filename(paths[i], original_real_uid);
 229                 xfree(paths[i]);
 230                 paths[i] = cp;
 231         }
 232 }
 233
 234 /*
 235  * Main program for the ssh client.
 236  */
 237 int
 238 main(int ac, char **av)
 239 {
 240         int i, r, opt, exit_status, use_syslog;
 241         char *p, *cp, *line, *argv0, buf[MAXPATHLEN], *host_arg;
 242         char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
 243         struct stat st;
 244         struct passwd *pw;
 245         int dummy, timeout_ms;
 246         extern int optind, optreset;
 247         extern char *optarg;
 248
 249         struct servent *sp;
 250         Forward fwd;
 251
 252         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 253         sanitise_stdfd();
 254
 255         __progname = ssh_get_progname(av[0]);
 256
 257 #ifndef HAVE_SETPROCTITLE
 258         /* Prepare for later setproctitle emulation */
 259         /* Save argv so it isn't clobbered by setproctitle() emulation */
 260         saved_av = xcalloc(ac + 1, sizeof(*saved_av));
 261         for (i = 0; i < ac; i++)
 262                 saved_av[i] = xstrdup(av[i]);
 263         saved_av[i] = NULL;
 264         compat_init_setproctitle(ac, av);
 265         av = saved_av;
 266 #endif
 267
 268         /*
 269          * Discard other fds that are hanging around. These can cause problem
 270          * with backgrounded ssh processes started by ControlPersist.
 271          */
 272         closefrom(STDERR_FILENO + 1);
 273
 274         /*
 275          * Save the original real uid.  It will be needed later (uid-swapping
 276          * may clobber the real uid).
 277          */
 278         original_real_uid = getuid();
 279         original_effective_uid = geteuid();
 280
 281         /*
 282          * Use uid-swapping to give up root privileges for the duration of
 283          * option processing.  We will re-instantiate the rights when we are
 284          * ready to create the privileged port, and will permanently drop
 285          * them when the port has been created (actually, when the connection
 286          * has been made, as we may need to create the port several times).
 287          */
 288         PRIV_END;
 289
 290 #ifdef HAVE_SETRLIMIT
 291         /* If we are installed setuid root be careful to not drop core. */
 292         if (original_real_uid != original_effective_uid) {
 293                 struct rlimit rlim;
 294                 rlim.rlim_cur = rlim.rlim_max = 0;
 295                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 296                         fatal("setrlimit failed: %.100s", strerror(errno));
 297         }
 298 #endif
 299         /* Get user data. */
 300         pw = getpwuid(original_real_uid);
 301         if (!pw) {
 302                 logit("You don't exist, go away!");
 303                 exit(255);
 304         }
 305         /* Take a copy of the returned structure. */
 306         pw = pwcopy(pw);
 307
 308         /*
 309          * Set our umask to something reasonable, as some files are created
 310          * with the default umask.  This will make them world-readable but
 311          * writable only by the owner, which is ok for all files for which we
 312          * don't set the modes explicitly.
 313          */
 314         umask(022);
 315
 316         /*
 317          * Initialize option structure to indicate that no values have been
 318          * set.
 319          */
 320         initialize_options(&options);
 321
 322         /* Parse command-line arguments. */
 323         host = NULL;
 324         use_syslog = 0;
 325         argv0 = av[0];
 326
 327  again:
 328         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 329             "ACD:F:I:KL:MNO:PR:S:TVw:W:XYy")) != -1) {
 330                 switch (opt) {
 331                 case '1':
 332                         options.protocol = SSH_PROTO_1;
 333                         break;
 334                 case '2':
 335                         options.protocol = SSH_PROTO_2;
 336                         break;
 337                 case '4':
 338                         options.address_family = AF_INET;
 339                         break;
 340                 case '6':
 341                         options.address_family = AF_INET6;
 342                         break;
 343                 case 'n':
 344                         stdin_null_flag = 1;
 345                         break;
 346                 case 'f':
 347                         fork_after_authentication_flag = 1;
 348                         stdin_null_flag = 1;
 349                         break;
 350                 case 'x':
 351                         options.forward_x11 = 0;
 352                         break;
 353                 case 'X':
 354                         options.forward_x11 = 1;
 355                         break;
 356                 case 'y':
 357                         use_syslog = 1;
 358                         break;
 359                 case 'Y':
 360                         options.forward_x11 = 1;
 361                         options.forward_x11_trusted = 1;
 362                         break;
 363                 case 'g':
 364                         options.gateway_ports = 1;
 365                         break;
 366                 case 'O':
 367                         if (stdio_forward_host != NULL)
 368                                 fatal("Cannot specify multiplexing "
 369                                     "command with -W");
 370                         else if (muxclient_command != 0)
 371                                 fatal("Multiplexing command already specified");
 372                         if (strcmp(optarg, "check") == 0)
 373                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 374                         else if (strcmp(optarg, "forward") == 0)
 375                                 muxclient_command = SSHMUX_COMMAND_FORWARD;
 376                         else if (strcmp(optarg, "exit") == 0)
 377                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 378                         else if (strcmp(optarg, "stop") == 0)
 379                                 muxclient_command = SSHMUX_COMMAND_STOP;
 380                         else if (strcmp(optarg, "cancel") == 0)
 381                                 muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
 382                         else
 383                                 fatal("Invalid multiplex command.");
 384                         break;
 385                 case 'P':       /* deprecated */
 386                         options.use_privileged_port = 0;
 387                         break;
 388                 case 'a':
 389                         options.forward_agent = 0;
 390                         break;
 391                 case 'A':
 392                         options.forward_agent = 1;
 393                         break;
 394                 case 'k':
 395                         options.gss_deleg_creds = 0;
 396                         break;
 397                 case 'K':
 398                         options.gss_authentication = 1;
 399                         options.gss_deleg_creds = 1;
 400                         break;
 401                 case 'i':
 402                         if (stat(optarg, &st) < 0) {
 403                                 fprintf(stderr, "Warning: Identity file %s "
 404                                     "not accessible: %s.\n", optarg,
 405                                     strerror(errno));
 406                                 break;
 407                         }
 408                         if (options.num_identity_files >=
 409                             SSH_MAX_IDENTITY_FILES)
 410                                 fatal("Too many identity files specified "
 411                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 412                         options.identity_files[options.num_identity_files++] =
 413                             xstrdup(optarg);
 414                         break;
 415                 case 'I':
 416 #ifdef ENABLE_PKCS11
 417                         options.pkcs11_provider = xstrdup(optarg);
 418 #else
 419                         fprintf(stderr, "no support for PKCS#11.\n");
 420 #endif
 421                         break;
 422                 case 't':
 423                         if (options.request_tty == REQUEST_TTY_YES)
 424                                 options.request_tty = REQUEST_TTY_FORCE;
 425                         else
 426                                 options.request_tty = REQUEST_TTY_YES;
 427                         break;
 428                 case 'v':
 429                         if (debug_flag == 0) {
 430                                 debug_flag = 1;
 431                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 432                         } else {
 433                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 434                                         options.log_level++;
 435                                 break;
 436                         }
 437                         /* FALLTHROUGH */
 438                 case 'V':
 439                         fprintf(stderr, "%s, %s\n",
 440                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 441                         if (opt == 'V')
 442                                 exit(0);
 443                         break;
 444                 case 'w':
 445                         if (options.tun_open == -1)
 446                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 447                         options.tun_local = a2tun(optarg, &options.tun_remote);
 448                         if (options.tun_local == SSH_TUNID_ERR) {
 449                                 fprintf(stderr,
 450                                     "Bad tun device '%s'\n", optarg);
 451                                 exit(255);
 452                         }
 453                         break;
 454                 case 'W':
 455                         if (stdio_forward_host != NULL)
 456                                 fatal("stdio forward already specified");
 457                         if (muxclient_command != 0)
 458                                 fatal("Cannot specify stdio forward with -O");
 459                         if (parse_forward(&fwd, optarg, 1, 0)) {
 460                                 stdio_forward_host = fwd.listen_host;
 461                                 stdio_forward_port = fwd.listen_port;
 462                                 xfree(fwd.connect_host);
 463                         } else {
 464                                 fprintf(stderr,
 465                                     "Bad stdio forwarding specification '%s'\n",
 466                                     optarg);
 467                                 exit(255);
 468                         }
 469                         options.request_tty = REQUEST_TTY_NO;
 470                         no_shell_flag = 1;
 471                         options.clear_forwardings = 1;
 472                         options.exit_on_forward_failure = 1;
 473                         break;
 474                 case 'q':
 475                         options.log_level = SYSLOG_LEVEL_QUIET;
 476                         break;
 477                 case 'e':
 478                         if (optarg[0] == '^' && optarg[2] == 0 &&
 479                             (u_char) optarg[1] >= 64 &&
 480                             (u_char) optarg[1] < 128)
 481                                 options.escape_char = (u_char) optarg[1] & 31;
 482                         else if (strlen(optarg) == 1)
 483                                 options.escape_char = (u_char) optarg[0];
 484                         else if (strcmp(optarg, "none") == 0)
 485                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 486                         else {
 487                                 fprintf(stderr, "Bad escape character '%s'.\n",
 488                                     optarg);
 489                                 exit(255);
 490                         }
 491                         break;
 492                 case 'c':
 493                         if (ciphers_valid(optarg)) {
 494                                 /* SSH2 only */
 495                                 options.ciphers = xstrdup(optarg);
 496                                 options.cipher = SSH_CIPHER_INVALID;
 497                         } else {
 498                                 /* SSH1 only */
 499                                 options.cipher = cipher_number(optarg);
 500                                 if (options.cipher == -1) {
 501                                         fprintf(stderr,
 502                                             "Unknown cipher type '%s'\n",
 503                                             optarg);
 504                                         exit(255);
 505                                 }
 506                                 if (options.cipher == SSH_CIPHER_3DES)
 507                                         options.ciphers = "3des-cbc";
 508                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 509                                         options.ciphers = "blowfish-cbc";
 510                                 else
 511                                         options.ciphers = (char *)-1;
 512                         }
 513                         break;
 514                 case 'm':
 515                         if (mac_valid(optarg))
 516                                 options.macs = xstrdup(optarg);
 517                         else {
 518                                 fprintf(stderr, "Unknown mac type '%s'\n",
 519                                     optarg);
 520                                 exit(255);
 521                         }
 522                         break;
 523                 case 'M':
 524                         if (options.control_master == SSHCTL_MASTER_YES)
 525                                 options.control_master = SSHCTL_MASTER_ASK;
 526                         else
 527                                 options.control_master = SSHCTL_MASTER_YES;
 528                         break;
 529                 case 'p':
 530                         options.port = a2port(optarg);
 531                         if (options.port <= 0) {
 532                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 533                                 exit(255);
 534                         }
 535                         break;
 536                 case 'l':
 537                         options.user = optarg;
 538                         break;
 539
 540                 case 'L':
 541                         if (parse_forward(&fwd, optarg, 0, 0))
 542                                 add_local_forward(&options, &fwd);
 543                         else {
 544                                 fprintf(stderr,
 545                                     "Bad local forwarding specification '%s'\n",
 546                                     optarg);
 547                                 exit(255);
 548                         }
 549                         break;
 550
 551                 case 'R':
 552                         if (parse_forward(&fwd, optarg, 0, 1)) {
 553                                 add_remote_forward(&options, &fwd);
 554                         } else {
 555                                 fprintf(stderr,
 556                                     "Bad remote forwarding specification "
 557                                     "'%s'\n", optarg);
 558                                 exit(255);
 559                         }
 560                         break;
 561
 562                 case 'D':
 563                         if (parse_forward(&fwd, optarg, 1, 0)) {
 564                                 add_local_forward(&options, &fwd);
 565                         } else {
 566                                 fprintf(stderr,
 567                                     "Bad dynamic forwarding specification "
 568                                     "'%s'\n", optarg);
 569                                 exit(255);
 570                         }
 571                         break;
 572
 573                 case 'C':
 574                         options.compression = 1;
 575                         break;
 576                 case 'N':
 577                         no_shell_flag = 1;
 578                         options.request_tty = REQUEST_TTY_NO;
 579                         break;
 580                 case 'T':
 581                         options.request_tty = REQUEST_TTY_NO;
 582                         break;
 583                 case 'o':
 584                         dummy = 1;
 585                         line = xstrdup(optarg);
 586                         if (process_config_line(&options, host ? host : "",
 587                             line, "command-line", 0, &dummy) != 0)
 588                                 exit(255);
 589                         xfree(line);
 590                         break;
 591                 case 's':
 592                         subsystem_flag = 1;
 593                         break;
 594                 case 'S':
 595                         if (options.control_path != NULL)
 596                                 free(options.control_path);
 597                         options.control_path = xstrdup(optarg);
 598                         break;
 599                 case 'b':
 600                         options.bind_address = optarg;
 601                         break;
 602                 case 'F':
 603                         config = optarg;
 604                         break;
 605                 default:
 606                         usage();
 607                 }
 608         }
 609
 610         ac -= optind;
 611         av += optind;
 612
 613         if (ac > 0 && !host) {
 614                 if (strrchr(*av, '@')) {
 615                         p = xstrdup(*av);
 616                         cp = strrchr(p, '@');
 617                         if (cp == NULL || cp == p)
 618                                 usage();
 619                         options.user = p;
 620                         *cp = '\0';
 621                         host = ++cp;
 622                 } else
 623                         host = *av;
 624                 if (ac > 1) {
 625                         optind = optreset = 1;
 626                         goto again;
 627                 }
 628                 ac--, av++;
 629         }
 630
 631         /* Check that we got a host name. */
 632         if (!host)
 633                 usage();
 634
 635         OpenSSL_add_all_algorithms();
 636         ERR_load_crypto_strings();
 637
 638         /* Initialize the command to execute on remote host. */
 639         buffer_init(&command);
 640
 641         /*
 642          * Save the command to execute on the remote host in a buffer. There
 643          * is no limit on the length of the command, except by the maximum
 644          * packet size.  Also sets the tty flag if there is no command.
 645          */
 646         if (!ac) {
 647                 /* No command specified - execute shell on a tty. */
 648                 if (subsystem_flag) {
 649                         fprintf(stderr,
 650                             "You must specify a subsystem to invoke.\n");
 651                         usage();
 652                 }
 653         } else {
 654                 /* A command has been specified.  Store it into the buffer. */
 655                 for (i = 0; i < ac; i++) {
 656                         if (i)
 657                                 buffer_append(&command, " ", 1);
 658                         buffer_append(&command, av[i], strlen(av[i]));
 659                 }
 660         }
 661
 662         /* Cannot fork to background if no command. */
 663         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 664             !no_shell_flag)
 665                 fatal("Cannot fork into background without a command "
 666                     "to execute.");
 667
 668         /*
 669          * Initialize "log" output.  Since we are the client all output
 670          * actually goes to stderr.
 671          */
 672         log_init(argv0,
 673             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 674             SYSLOG_FACILITY_USER, !use_syslog);
 675
 676         /*
 677          * Read per-user configuration file.  Ignore the system wide config
 678          * file if the user specifies a config file on the command line.
 679          */
 680         if (config != NULL) {
 681                 if (!read_config_file(config, host, &options, 0))
 682                         fatal("Can't open user config file %.100s: "
 683                             "%.100s", config, strerror(errno));
 684         } else {
 685                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 686                     _PATH_SSH_USER_CONFFILE);
 687                 if (r > 0 && (size_t)r < sizeof(buf))
 688                         (void)read_config_file(buf, host, &options, 1);
 689
 690                 /* Read systemwide configuration file after user config. */
 691                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 692                     &options, 0);
 693         }
 694
 695         /* Fill configuration defaults. */
 696         fill_default_options(&options);
 697
 698         channel_set_af(options.address_family);
 699
 700         /* reinit */
 701         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 702
 703         if (options.request_tty == REQUEST_TTY_YES ||
 704             options.request_tty == REQUEST_TTY_FORCE)
 705                 tty_flag = 1;
 706
 707         /* Allocate a tty by default if no command specified. */
 708         if (buffer_len(&command) == 0)
 709                 tty_flag = options.request_tty != REQUEST_TTY_NO;
 710
 711         /* Force no tty */
 712         if (options.request_tty == REQUEST_TTY_NO || muxclient_command != 0)
 713                 tty_flag = 0;
 714         /* Do not allocate a tty if stdin is not a tty. */
 715         if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
 716             options.request_tty != REQUEST_TTY_FORCE) {
 717                 if (tty_flag)
 718                         logit("Pseudo-terminal will not be allocated because "
 719                             "stdin is not a terminal.");
 720                 tty_flag = 0;
 721         }
 722
 723         seed_rng();
 724
 725         if (options.user == NULL)
 726                 options.user = xstrdup(pw->pw_name);
 727
 728         /* Get default port if port has not been set. */
 729         if (options.port == 0) {
 730                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 731                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 732         }
 733
 734         /* preserve host name given on command line for %n expansion */
 735         host_arg = host;
 736         if (options.hostname != NULL) {
 737                 host = percent_expand(options.hostname,
 738                     "h", host, (char *)NULL);
 739         }
 740
 741         if (gethostname(thishost, sizeof(thishost)) == -1)
 742                 fatal("gethostname: %s", strerror(errno));
 743         strlcpy(shorthost, thishost, sizeof(shorthost));
 744         shorthost[strcspn(thishost, ".")] = '\0';
 745         snprintf(portstr, sizeof(portstr), "%d", options.port);
 746
 747         if (options.local_command != NULL) {
 748                 debug3("expanding LocalCommand: %s", options.local_command);
 749                 cp = options.local_command;
 750                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 751                     "h", host, "l", thishost, "n", host_arg, "r", options.user,
 752                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 753                     (char *)NULL);
 754                 debug3("expanded LocalCommand: %s", options.local_command);
 755                 xfree(cp);
 756         }
 757
 758         /* force lowercase for hostkey matching */
 759         if (options.host_key_alias != NULL) {
 760                 for (p = options.host_key_alias; *p; p++)
 761                         if (isupper(*p))
 762                                 *p = (char)tolower(*p);
 763         }
 764
 765         if (options.proxy_command != NULL &&
 766             strcmp(options.proxy_command, "none") == 0) {
 767                 xfree(options.proxy_command);
 768                 options.proxy_command = NULL;
 769         }
 770         if (options.control_path != NULL &&
 771             strcmp(options.control_path, "none") == 0) {
 772                 xfree(options.control_path);
 773                 options.control_path = NULL;
 774         }
 775
 776         if (options.control_path != NULL) {
 777                 cp = tilde_expand_filename(options.control_path,
 778                     original_real_uid);
 779                 xfree(options.control_path);
 780                 options.control_path = percent_expand(cp, "h", host,
 781                     "l", thishost, "n", host_arg, "r", options.user,
 782                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 783                     (char *)NULL);
 784                 xfree(cp);
 785         }
 786         if (muxclient_command != 0 && options.control_path == NULL)
 787                 fatal("No ControlPath specified for \"-O\" command");
 788         if (options.control_path != NULL)
 789                 muxclient(options.control_path);
 790
 791         timeout_ms = options.connection_timeout * 1000;
 792
 793         /* Open a connection to the remote host. */
 794         if (ssh_connect(host, &hostaddr, options.port,
 795             options.address_family, options.connection_attempts, &timeout_ms,
 796             options.tcp_keep_alive,
 797 #ifdef HAVE_CYGWIN
 798             options.use_privileged_port,
 799 #else
 800             original_effective_uid == 0 && options.use_privileged_port,
 801 #endif
 802             options.proxy_command) != 0)
 803                 exit(255);
 804
 805         if (timeout_ms > 0)
 806                 debug3("timeout: %d ms remain after connect", timeout_ms);
 807
 808         /*
 809          * If we successfully made the connection, load the host private key
 810          * in case we will need it later for combined rsa-rhosts
 811          * authentication. This must be done before releasing extra
 812          * privileges, because the file is only readable by root.
 813          * If we cannot access the private keys, load the public keys
 814          * instead and try to execute the ssh-keysign helper instead.
 815          */
 816         sensitive_data.nkeys = 0;
 817         sensitive_data.keys = NULL;
 818         sensitive_data.external_keysign = 0;
 819         if (options.rhosts_rsa_authentication ||
 820             options.hostbased_authentication) {
 821                 sensitive_data.nkeys = 7;
 822                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 823                     sizeof(Key));
 824                 for (i = 0; i < sensitive_data.nkeys; i++)
 825                         sensitive_data.keys[i] = NULL;
 826
 827                 PRIV_START;
 828                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 829                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 830                 sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
 831                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 832 #ifdef OPENSSL_HAS_ECC
 833                 sensitive_data.keys[2] = key_load_private_cert(KEY_ECDSA,
 834                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
 835 #endif
 836                 sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
 837                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 838                 sensitive_data.keys[4] = key_load_private_type(KEY_DSA,
 839                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 840 #ifdef OPENSSL_HAS_ECC
 841                 sensitive_data.keys[5] = key_load_private_type(KEY_ECDSA,
 842                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
 843 #endif
 844                 sensitive_data.keys[6] = key_load_private_type(KEY_RSA,
 845                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 846                 PRIV_END;
 847
 848                 if (options.hostbased_authentication == 1 &&
 849                     sensitive_data.keys[0] == NULL &&
 850                     sensitive_data.keys[4] == NULL &&
 851                     sensitive_data.keys[5] == NULL &&
 852                     sensitive_data.keys[6] == NULL) {
 853                         sensitive_data.keys[1] = key_load_cert(
 854                             _PATH_HOST_DSA_KEY_FILE);
 855 #ifdef OPENSSL_HAS_ECC
 856                         sensitive_data.keys[2] = key_load_cert(
 857                             _PATH_HOST_ECDSA_KEY_FILE);
 858 #endif
 859                         sensitive_data.keys[3] = key_load_cert(
 860                             _PATH_HOST_RSA_KEY_FILE);
 861                         sensitive_data.keys[4] = key_load_public(
 862                             _PATH_HOST_DSA_KEY_FILE, NULL);
 863 #ifdef OPENSSL_HAS_ECC
 864                         sensitive_data.keys[5] = key_load_public(
 865                             _PATH_HOST_ECDSA_KEY_FILE, NULL);
 866 #endif
 867                         sensitive_data.keys[6] = key_load_public(
 868                             _PATH_HOST_RSA_KEY_FILE, NULL);
 869                         sensitive_data.external_keysign = 1;
 870                 }
 871         }
 872         /*
 873          * Get rid of any extra privileges that we may have.  We will no
 874          * longer need them.  Also, extra privileges could make it very hard
 875          * to read identity files and other non-world-readable files from the
 876          * user's home directory if it happens to be on a NFS volume where
 877          * root is mapped to nobody.
 878          */
 879         if (original_effective_uid == 0) {
 880                 PRIV_START;
 881                 permanently_set_uid(pw);
 882         }
 883
 884         /*
 885          * Now that we are back to our own permissions, create ~/.ssh
 886          * directory if it doesn't already exist.
 887          */
 888         if (config == NULL) {
 889                 r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
 890                     strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 891                 if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
 892 #ifdef WITH_SELINUX
 893                         ssh_selinux_setfscreatecon(buf);
 894 #endif
 895                         if (mkdir(buf, 0700) < 0)
 896                                 error("Could not create directory '%.200s'.",
 897                                     buf);
 898 #ifdef WITH_SELINUX
 899                         ssh_selinux_setfscreatecon(NULL);
 900 #endif
 901                 }
 902         }
 903         /* load options.identity_files */
 904         load_public_identity_files();
 905
 906         /* Expand ~ in known host file names. */
 907         tilde_expand_paths(options.system_hostfiles,
 908             options.num_system_hostfiles);
 909         tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
 910
 911         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 912         signal(SIGCHLD, main_sigchld_handler);
 913
 914         /* Log into the remote system.  Never returns if the login fails. */
 915         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 916             options.port, pw, timeout_ms);
 917
 918         if (packet_connection_is_on_socket()) {
 919                 verbose("Authenticated to %s ([%s]:%d).", host,
 920                     get_remote_ipaddr(), get_remote_port());
 921         } else {
 922                 verbose("Authenticated to %s (via proxy).", host);
 923         }
 924
 925         /* We no longer need the private host keys.  Clear them now. */
 926         if (sensitive_data.nkeys != 0) {
 927                 for (i = 0; i < sensitive_data.nkeys; i++) {
 928                         if (sensitive_data.keys[i] != NULL) {
 929                                 /* Destroys contents safely */
 930                                 debug3("clear hostkey %d", i);
 931                                 key_free(sensitive_data.keys[i]);
 932                                 sensitive_data.keys[i] = NULL;
 933                         }
 934                 }
 935                 xfree(sensitive_data.keys);
 936         }
 937         for (i = 0; i < options.num_identity_files; i++) {
 938                 if (options.identity_files[i]) {
 939                         xfree(options.identity_files[i]);
 940                         options.identity_files[i] = NULL;
 941                 }
 942                 if (options.identity_keys[i]) {
 943                         key_free(options.identity_keys[i]);
 944                         options.identity_keys[i] = NULL;
 945                 }
 946         }
 947
 948         exit_status = compat20 ? ssh_session2() : ssh_session();
 949         packet_close();
 950
 951         if (options.control_path != NULL && muxserver_sock != -1)
 952                 unlink(options.control_path);
 953
 954         /* Kill ProxyCommand if it is running. */
 955         ssh_kill_proxy_command();
 956
 957         return exit_status;
 958 }
 959
 960 static void
 961 control_persist_detach(void)
 962 {
 963         pid_t pid;
 964         int devnull;
 965
 966         debug("%s: backgrounding master process", __func__);
 967
 968         /*
 969          * master (current process) into the background, and make the
 970          * foreground process a client of the backgrounded master.
 971          */
 972         switch ((pid = fork())) {
 973         case -1:
 974                 fatal("%s: fork: %s", __func__, strerror(errno));
 975         case 0:
 976                 /* Child: master process continues mainloop */
 977                 break;
 978         default:
 979                 /* Parent: set up mux slave to connect to backgrounded master */
 980                 debug2("%s: background process is %ld", __func__, (long)pid);
 981                 stdin_null_flag = ostdin_null_flag;
 982                 options.request_tty = orequest_tty;
 983                 tty_flag = otty_flag;
 984                 close(muxserver_sock);
 985                 muxserver_sock = -1;
 986                 options.control_master = SSHCTL_MASTER_NO;
 987                 muxclient(options.control_path);
 988                 /* muxclient() doesn't return on success. */
 989                 fatal("Failed to connect to new control master");
 990         }
 991         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
 992                 error("%s: open(\"/dev/null\"): %s", __func__,
 993                     strerror(errno));
 994         } else {
 995                 if (dup2(devnull, STDIN_FILENO) == -1 ||
 996                     dup2(devnull, STDOUT_FILENO) == -1)
 997                         error("%s: dup2: %s", __func__, strerror(errno));
 998                 if (devnull > STDERR_FILENO)
 999                         close(devnull);
1000         }
1001         setproctitle("%s [mux]", options.control_path);
1002 }
1003
1004 /* Do fork() after authentication. Used by "ssh -f" */
1005 static void
1006 fork_postauth(void)
1007 {
1008         if (need_controlpersist_detach)
1009                 control_persist_detach();
1010         debug("forking to background");
1011         fork_after_authentication_flag = 0;
1012         if (daemon(1, 1) < 0)
1013                 fatal("daemon() failed: %.200s", strerror(errno));
1014 }
1015
1016 /* Callback for remote forward global requests */
1017 static void
1018 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
1019 {
1020         Forward *rfwd = (Forward *)ctxt;
1021
1022         /* XXX verbose() on failure? */
1023         debug("remote forward %s for: listen %d, connect %s:%d",
1024             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1025             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
1026         if (rfwd->listen_port == 0) {
1027                 if (type == SSH2_MSG_REQUEST_SUCCESS) {
1028                         rfwd->allocated_port = packet_get_int();
1029                         logit("Allocated port %u for remote forward to %s:%d",
1030                             rfwd->allocated_port,
1031                             rfwd->connect_host, rfwd->connect_port);
1032                         channel_update_permitted_opens(rfwd->handle,
1033                             rfwd->allocated_port);
1034                 } else {
1035                         channel_update_permitted_opens(rfwd->handle, -1);
1036                 }
1037         }
1038
1039         if (type == SSH2_MSG_REQUEST_FAILURE) {
1040                 if (options.exit_on_forward_failure)
1041                         fatal("Error: remote port forwarding failed for "
1042                             "listen port %d", rfwd->listen_port);
1043                 else
1044                         logit("Warning: remote port forwarding failed for "
1045                             "listen port %d", rfwd->listen_port);
1046         }
1047         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1048                 debug("All remote forwarding requests processed");
1049                 if (fork_after_authentication_flag)
1050                         fork_postauth();
1051         }
1052 }
1053
1054 static void
1055 client_cleanup_stdio_fwd(int id, void *arg)
1056 {
1057         debug("stdio forwarding: done");
1058         cleanup_exit(0);
1059 }
1060
1061 static void
1062 ssh_init_stdio_forwarding(void)
1063 {
1064         Channel *c;
1065         int in, out;
1066
1067         if (stdio_forward_host == NULL)
1068                 return;
1069         if (!compat20)
1070                 fatal("stdio forwarding require Protocol 2");
1071
1072         debug3("%s: %s:%d", __func__, stdio_forward_host, stdio_forward_port);
1073
1074         if ((in = dup(STDIN_FILENO)) < 0 ||
1075             (out = dup(STDOUT_FILENO)) < 0)
1076                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1077         if ((c = channel_connect_stdio_fwd(stdio_forward_host,
1078             stdio_forward_port, in, out)) == NULL)
1079                 fatal("%s: channel_connect_stdio_fwd failed", __func__);
1080         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1081 }
1082
1083 static void
1084 ssh_init_forwarding(void)
1085 {
1086         int success = 0;
1087         int i;
1088
1089         /* Initiate local TCP/IP port forwardings. */
1090         for (i = 0; i < options.num_local_forwards; i++) {
1091                 debug("Local connections to %.200s:%d forwarded to remote "
1092                     "address %.200s:%d",
1093                     (options.local_forwards[i].listen_host == NULL) ?
1094                     (options.gateway_ports ? "*" : "LOCALHOST") :
1095                     options.local_forwards[i].listen_host,
1096                     options.local_forwards[i].listen_port,
1097                     options.local_forwards[i].connect_host,
1098                     options.local_forwards[i].connect_port);
1099                 success += channel_setup_local_fwd_listener(
1100                     options.local_forwards[i].listen_host,
1101                     options.local_forwards[i].listen_port,
1102                     options.local_forwards[i].connect_host,
1103                     options.local_forwards[i].connect_port,
1104                     options.gateway_ports);
1105         }
1106         if (i > 0 && success != i && options.exit_on_forward_failure)
1107                 fatal("Could not request local forwarding.");
1108         if (i > 0 && success == 0)
1109                 error("Could not request local forwarding.");
1110
1111         /* Initiate remote TCP/IP port forwardings. */
1112         for (i = 0; i < options.num_remote_forwards; i++) {
1113                 debug("Remote connections from %.200s:%d forwarded to "
1114                     "local address %.200s:%d",
1115                     (options.remote_forwards[i].listen_host == NULL) ?
1116                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1117                     options.remote_forwards[i].listen_port,
1118                     options.remote_forwards[i].connect_host,
1119                     options.remote_forwards[i].connect_port);
1120                 options.remote_forwards[i].handle =
1121                     channel_request_remote_forwarding(
1122                     options.remote_forwards[i].listen_host,
1123                     options.remote_forwards[i].listen_port,
1124                     options.remote_forwards[i].connect_host,
1125                     options.remote_forwards[i].connect_port);
1126                 if (options.remote_forwards[i].handle < 0) {
1127                         if (options.exit_on_forward_failure)
1128                                 fatal("Could not request remote forwarding.");
1129                         else
1130                                 logit("Warning: Could not request remote "
1131                                     "forwarding.");
1132                 } else {
1133                         client_register_global_confirm(ssh_confirm_remote_forward,
1134                             &options.remote_forwards[i]);
1135                 }
1136         }
1137
1138         /* Initiate tunnel forwarding. */
1139         if (options.tun_open != SSH_TUNMODE_NO) {
1140                 if (client_request_tun_fwd(options.tun_open,
1141                     options.tun_local, options.tun_remote) == -1) {
1142                         if (options.exit_on_forward_failure)
1143                                 fatal("Could not request tunnel forwarding.");
1144                         else
1145                                 error("Could not request tunnel forwarding.");
1146                 }
1147         }
1148 }
1149
1150 static void
1151 check_agent_present(void)
1152 {
1153         if (options.forward_agent) {
1154                 /* Clear agent forwarding if we don't have an agent. */
1155                 if (!ssh_agent_present())
1156                         options.forward_agent = 0;
1157         }
1158 }
1159
1160 static int
1161 ssh_session(void)
1162 {
1163         int type;
1164         int interactive = 0;
1165         int have_tty = 0;
1166         struct winsize ws;
1167         char *cp;
1168         const char *display;
1169
1170         /* Enable compression if requested. */
1171         if (options.compression) {
1172                 debug("Requesting compression at level %d.",
1173                     options.compression_level);
1174
1175                 if (options.compression_level < 1 ||
1176                     options.compression_level > 9)
1177                         fatal("Compression level must be from 1 (fast) to "
1178                             "9 (slow, best).");
1179
1180                 /* Send the request. */
1181                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1182                 packet_put_int(options.compression_level);
1183                 packet_send();
1184                 packet_write_wait();
1185                 type = packet_read();
1186                 if (type == SSH_SMSG_SUCCESS)
1187                         packet_start_compression(options.compression_level);
1188                 else if (type == SSH_SMSG_FAILURE)
1189                         logit("Warning: Remote host refused compression.");
1190                 else
1191                         packet_disconnect("Protocol error waiting for "
1192                             "compression response.");
1193         }
1194         /* Allocate a pseudo tty if appropriate. */
1195         if (tty_flag) {
1196                 debug("Requesting pty.");
1197
1198                 /* Start the packet. */
1199                 packet_start(SSH_CMSG_REQUEST_PTY);
1200
1201                 /* Store TERM in the packet.  There is no limit on the
1202                    length of the string. */
1203                 cp = getenv("TERM");
1204                 if (!cp)
1205                         cp = "";
1206                 packet_put_cstring(cp);
1207
1208                 /* Store window size in the packet. */
1209                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1210                         memset(&ws, 0, sizeof(ws));
1211                 packet_put_int((u_int)ws.ws_row);
1212                 packet_put_int((u_int)ws.ws_col);
1213                 packet_put_int((u_int)ws.ws_xpixel);
1214                 packet_put_int((u_int)ws.ws_ypixel);
1215
1216                 /* Store tty modes in the packet. */
1217                 tty_make_modes(fileno(stdin), NULL);
1218
1219                 /* Send the packet, and wait for it to leave. */
1220                 packet_send();
1221                 packet_write_wait();
1222
1223                 /* Read response from the server. */
1224                 type = packet_read();
1225                 if (type == SSH_SMSG_SUCCESS) {
1226                         interactive = 1;
1227                         have_tty = 1;
1228                 } else if (type == SSH_SMSG_FAILURE)
1229                         logit("Warning: Remote host failed or refused to "
1230                             "allocate a pseudo tty.");
1231                 else
1232                         packet_disconnect("Protocol error waiting for pty "
1233                             "request response.");
1234         }
1235         /* Request X11 forwarding if enabled and DISPLAY is set. */
1236         display = getenv("DISPLAY");
1237         if (options.forward_x11 && display != NULL) {
1238                 char *proto, *data;
1239                 /* Get reasonable local authentication information. */
1240                 client_x11_get_proto(display, options.xauth_location,
1241                     options.forward_x11_trusted,
1242                     options.forward_x11_timeout,
1243                     &proto, &data);
1244                 /* Request forwarding with authentication spoofing. */
1245                 debug("Requesting X11 forwarding with authentication "
1246                     "spoofing.");
1247                 x11_request_forwarding_with_spoofing(0, display, proto,
1248                     data, 0);
1249                 /* Read response from the server. */
1250                 type = packet_read();
1251                 if (type == SSH_SMSG_SUCCESS) {
1252                         interactive = 1;
1253                 } else if (type == SSH_SMSG_FAILURE) {
1254                         logit("Warning: Remote host denied X11 forwarding.");
1255                 } else {
1256                         packet_disconnect("Protocol error waiting for X11 "
1257                             "forwarding");
1258                 }
1259         }
1260         /* Tell the packet module whether this is an interactive session. */
1261         packet_set_interactive(interactive,
1262             options.ip_qos_interactive, options.ip_qos_bulk);
1263
1264         /* Request authentication agent forwarding if appropriate. */
1265         check_agent_present();
1266
1267         if (options.forward_agent) {
1268                 debug("Requesting authentication agent forwarding.");
1269                 auth_request_forwarding();
1270
1271                 /* Read response from the server. */
1272                 type = packet_read();
1273                 packet_check_eom();
1274                 if (type != SSH_SMSG_SUCCESS)
1275                         logit("Warning: Remote host denied authentication agent forwarding.");
1276         }
1277
1278         /* Initiate port forwardings. */
1279         ssh_init_stdio_forwarding();
1280         ssh_init_forwarding();
1281
1282         /* Execute a local command */
1283         if (options.local_command != NULL &&
1284             options.permit_local_command)
1285                 ssh_local_cmd(options.local_command);
1286
1287         /*
1288          * If requested and we are not interested in replies to remote
1289          * forwarding requests, then let ssh continue in the background.
1290          */
1291         if (fork_after_authentication_flag) {
1292                 if (options.exit_on_forward_failure &&
1293                     options.num_remote_forwards > 0) {
1294                         debug("deferring postauth fork until remote forward "
1295                             "confirmation received");
1296                 } else
1297                         fork_postauth();
1298         }
1299
1300         /*
1301          * If a command was specified on the command line, execute the
1302          * command now. Otherwise request the server to start a shell.
1303          */
1304         if (buffer_len(&command) > 0) {
1305                 int len = buffer_len(&command);
1306                 if (len > 900)
1307                         len = 900;
1308                 debug("Sending command: %.*s", len,
1309                     (u_char *)buffer_ptr(&command));
1310                 packet_start(SSH_CMSG_EXEC_CMD);
1311                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1312                 packet_send();
1313                 packet_write_wait();
1314         } else {
1315                 debug("Requesting shell.");
1316                 packet_start(SSH_CMSG_EXEC_SHELL);
1317                 packet_send();
1318                 packet_write_wait();
1319         }
1320
1321         /* Enter the interactive session. */
1322         return client_loop(have_tty, tty_flag ?
1323             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1324 }
1325
1326 /* request pty/x11/agent/tcpfwd/shell for channel */
1327 static void
1328 ssh_session2_setup(int id, int success, void *arg)
1329 {
1330         extern char **environ;
1331         const char *display;
1332         int interactive = tty_flag;
1333
1334         if (!success)
1335                 return; /* No need for error message, channels code sens one */
1336
1337         display = getenv("DISPLAY");
1338         if (options.forward_x11 && display != NULL) {
1339                 char *proto, *data;
1340                 /* Get reasonable local authentication information. */
1341                 client_x11_get_proto(display, options.xauth_location,
1342                     options.forward_x11_trusted,
1343                     options.forward_x11_timeout, &proto, &data);
1344                 /* Request forwarding with authentication spoofing. */
1345                 debug("Requesting X11 forwarding with authentication "
1346                     "spoofing.");
1347                 x11_request_forwarding_with_spoofing(id, display, proto,
1348                     data, 1);
1349                 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
1350                 /* XXX exit_on_forward_failure */
1351                 interactive = 1;
1352         }
1353
1354         check_agent_present();
1355         if (options.forward_agent) {
1356                 debug("Requesting authentication agent forwarding.");
1357                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1358                 packet_send();
1359         }
1360
1361         /* Tell the packet module whether this is an interactive session. */
1362         packet_set_interactive(interactive,
1363             options.ip_qos_interactive, options.ip_qos_bulk);
1364
1365         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1366             NULL, fileno(stdin), &command, environ);
1367 }
1368
1369 /* open new channel for a session */
1370 static int
1371 ssh_session2_open(void)
1372 {
1373         Channel *c;
1374         int window, packetmax, in, out, err;
1375
1376         if (stdin_null_flag) {
1377                 in = open(_PATH_DEVNULL, O_RDONLY);
1378         } else {
1379                 in = dup(STDIN_FILENO);
1380         }
1381         out = dup(STDOUT_FILENO);
1382         err = dup(STDERR_FILENO);
1383
1384         if (in < 0 || out < 0 || err < 0)
1385                 fatal("dup() in/out/err failed");
1386
1387         /* enable nonblocking unless tty */
1388         if (!isatty(in))
1389                 set_nonblock(in);
1390         if (!isatty(out))
1391                 set_nonblock(out);
1392         if (!isatty(err))
1393                 set_nonblock(err);
1394
1395         window = CHAN_SES_WINDOW_DEFAULT;
1396         packetmax = CHAN_SES_PACKET_DEFAULT;
1397         if (tty_flag) {
1398                 window >>= 1;
1399                 packetmax >>= 1;
1400         }
1401         c = channel_new(
1402             "session", SSH_CHANNEL_OPENING, in, out, err,
1403             window, packetmax, CHAN_EXTENDED_WRITE,
1404             "client-session", /*nonblock*/0);
1405
1406         debug3("ssh_session2_open: channel_new: %d", c->self);
1407
1408         channel_send_open(c->self);
1409         if (!no_shell_flag)
1410                 channel_register_open_confirm(c->self,
1411                     ssh_session2_setup, NULL);
1412
1413         return c->self;
1414 }
1415
1416 static int
1417 ssh_session2(void)
1418 {
1419         int id = -1;
1420
1421         /* XXX should be pre-session */
1422         if (!options.control_persist)
1423                 ssh_init_stdio_forwarding();
1424         ssh_init_forwarding();
1425
1426         /* Start listening for multiplex clients */
1427         muxserver_listen();
1428
1429         /*
1430          * If we are in control persist mode and have a working mux listen
1431          * socket, then prepare to background ourselves and have a foreground
1432          * client attach as a control slave.
1433          * NB. we must save copies of the flags that we override for
1434          * the backgrounding, since we defer attachment of the slave until
1435          * after the connection is fully established (in particular,
1436          * async rfwd replies have been received for ExitOnForwardFailure).
1437          */
1438         if (options.control_persist && muxserver_sock != -1) {
1439                 ostdin_null_flag = stdin_null_flag;
1440                 ono_shell_flag = no_shell_flag;
1441                 orequest_tty = options.request_tty;
1442                 otty_flag = tty_flag;
1443                 stdin_null_flag = 1;
1444                 no_shell_flag = 1;
1445                 tty_flag = 0;
1446                 if (!fork_after_authentication_flag)
1447                         need_controlpersist_detach = 1;
1448                 fork_after_authentication_flag = 1;
1449         }
1450         /*
1451          * ControlPersist mux listen socket setup failed, attempt the
1452          * stdio forward setup that we skipped earlier.
1453          */
1454         if (options.control_persist && muxserver_sock == -1)
1455                 ssh_init_stdio_forwarding();
1456
1457         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1458                 id = ssh_session2_open();
1459
1460         /* If we don't expect to open a new session, then disallow it */
1461         if (options.control_master == SSHCTL_MASTER_NO &&
1462             (datafellows & SSH_NEW_OPENSSH)) {
1463                 debug("Requesting no-more-sessions@openssh.com");
1464                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1465                 packet_put_cstring("no-more-sessions@openssh.com");
1466                 packet_put_char(0);
1467                 packet_send();
1468         }
1469
1470         /* Execute a local command */
1471         if (options.local_command != NULL &&
1472             options.permit_local_command)
1473                 ssh_local_cmd(options.local_command);
1474
1475         /*
1476          * If requested and we are not interested in replies to remote
1477          * forwarding requests, then let ssh continue in the background.
1478          */
1479         if (fork_after_authentication_flag) {
1480                 if (options.exit_on_forward_failure &&
1481                     options.num_remote_forwards > 0) {
1482                         debug("deferring postauth fork until remote forward "
1483                             "confirmation received");
1484                 } else
1485                         fork_postauth();
1486         }
1487
1488         if (options.use_roaming)
1489                 request_roaming();
1490
1491         return client_loop(tty_flag, tty_flag ?
1492             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1493 }
1494
1495 static void
1496 load_public_identity_files(void)
1497 {
1498         char *filename, *cp, thishost[NI_MAXHOST];
1499         char *pwdir = NULL, *pwname = NULL;
1500         int i = 0;
1501         Key *public;
1502         struct passwd *pw;
1503         u_int n_ids;
1504         char *identity_files[SSH_MAX_IDENTITY_FILES];
1505         Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1506 #ifdef ENABLE_PKCS11
1507         Key **keys;
1508         int nkeys;
1509 #endif /* PKCS11 */
1510
1511         n_ids = 0;
1512         bzero(identity_files, sizeof(identity_files));
1513         bzero(identity_keys, sizeof(identity_keys));
1514
1515 #ifdef ENABLE_PKCS11
1516         if (options.pkcs11_provider != NULL &&
1517             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1518             (pkcs11_init(!options.batch_mode) == 0) &&
1519             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1520             &keys)) > 0) {
1521                 for (i = 0; i < nkeys; i++) {
1522                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1523                                 key_free(keys[i]);
1524                                 continue;
1525                         }
1526                         identity_keys[n_ids] = keys[i];
1527                         identity_files[n_ids] =
1528                             xstrdup(options.pkcs11_provider); /* XXX */
1529                         n_ids++;
1530                 }
1531                 xfree(keys);
1532         }
1533 #endif /* ENABLE_PKCS11 */
1534         if ((pw = getpwuid(original_real_uid)) == NULL)
1535                 fatal("load_public_identity_files: getpwuid failed");
1536         pwname = xstrdup(pw->pw_name);
1537         pwdir = xstrdup(pw->pw_dir);
1538         if (gethostname(thishost, sizeof(thishost)) == -1)
1539                 fatal("load_public_identity_files: gethostname: %s",
1540                     strerror(errno));
1541         for (i = 0; i < options.num_identity_files; i++) {
1542                 if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1543                         xfree(options.identity_files[i]);
1544                         continue;
1545                 }
1546                 cp = tilde_expand_filename(options.identity_files[i],
1547                     original_real_uid);
1548                 filename = percent_expand(cp, "d", pwdir,
1549                     "u", pwname, "l", thishost, "h", host,
1550                     "r", options.user, (char *)NULL);
1551                 xfree(cp);
1552                 public = key_load_public(filename, NULL);
1553                 debug("identity file %s type %d", filename,
1554                     public ? public->type : -1);
1555                 xfree(options.identity_files[i]);
1556                 identity_files[n_ids] = filename;
1557                 identity_keys[n_ids] = public;
1558
1559                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
1560                         continue;
1561
1562                 /* Try to add the certificate variant too */
1563                 xasprintf(&cp, "%s-cert", filename);
1564                 public = key_load_public(cp, NULL);
1565                 debug("identity file %s type %d", cp,
1566                     public ? public->type : -1);
1567                 if (public == NULL) {
1568                         xfree(cp);
1569                         continue;
1570                 }
1571                 if (!key_is_cert(public)) {
1572                         debug("%s: key %s type %s is not a certificate",
1573                             __func__, cp, key_type(public));
1574                         key_free(public);
1575                         xfree(cp);
1576                         continue;
1577                 }
1578                 identity_keys[n_ids] = public;
1579                 /* point to the original path, most likely the private key */
1580                 identity_files[n_ids] = xstrdup(filename);
1581                 n_ids++;
1582         }
1583         options.num_identity_files = n_ids;
1584         memcpy(options.identity_files, identity_files, sizeof(identity_files));
1585         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
1586
1587         bzero(pwname, strlen(pwname));
1588         xfree(pwname);
1589         bzero(pwdir, strlen(pwdir));
1590         xfree(pwdir);
1591 }
1592
1593 static void
1594 main_sigchld_handler(int sig)
1595 {
1596         int save_errno = errno;
1597         pid_t pid;
1598         int status;
1599
1600         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
1601             (pid < 0 && errno == EINTR))
1602                 ;
1603
1604         signal(sig, main_sigchld_handler);
1605         errno = save_errno;
1606 }
1607