crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.364 2011/08/02 23:15:03 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
 381                                 fatal("Invalid multiplex command.");
 382                         break;
 383                 case 'P':       /* deprecated */
 384                         options.use_privileged_port = 0;
 385                         break;
 386                 case 'a':
 387                         options.forward_agent = 0;
 388                         break;
 389                 case 'A':
 390                         options.forward_agent = 1;
 391                         break;
 392                 case 'k':
 393                         options.gss_deleg_creds = 0;
 394                         break;
 395                 case 'K':
 396                         options.gss_authentication = 1;
 397                         options.gss_deleg_creds = 1;
 398                         break;
 399                 case 'i':
 400                         if (stat(optarg, &st) < 0) {
 401                                 fprintf(stderr, "Warning: Identity file %s "
 402                                     "not accessible: %s.\n", optarg,
 403                                     strerror(errno));
 404                                 break;
 405                         }
 406                         if (options.num_identity_files >=
 407                             SSH_MAX_IDENTITY_FILES)
 408                                 fatal("Too many identity files specified "
 409                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 410                         options.identity_files[options.num_identity_files++] =
 411                             xstrdup(optarg);
 412                         break;
 413                 case 'I':
 414 #ifdef ENABLE_PKCS11
 415                         options.pkcs11_provider = xstrdup(optarg);
 416 #else
 417                         fprintf(stderr, "no support for PKCS#11.\n");
 418 #endif
 419                         break;
 420                 case 't':
 421                         if (options.request_tty == REQUEST_TTY_YES)
 422                                 options.request_tty = REQUEST_TTY_FORCE;
 423                         else
 424                                 options.request_tty = REQUEST_TTY_YES;
 425                         break;
 426                 case 'v':
 427                         if (debug_flag == 0) {
 428                                 debug_flag = 1;
 429                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 430                         } else {
 431                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 432                                         options.log_level++;
 433                                 break;
 434                         }
 435                         /* FALLTHROUGH */
 436                 case 'V':
 437                         fprintf(stderr, "%s, %s\n",
 438                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 439                         if (opt == 'V')
 440                                 exit(0);
 441                         break;
 442                 case 'w':
 443                         if (options.tun_open == -1)
 444                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 445                         options.tun_local = a2tun(optarg, &options.tun_remote);
 446                         if (options.tun_local == SSH_TUNID_ERR) {
 447                                 fprintf(stderr,
 448                                     "Bad tun device '%s'\n", optarg);
 449                                 exit(255);
 450                         }
 451                         break;
 452                 case 'W':
 453                         if (stdio_forward_host != NULL)
 454                                 fatal("stdio forward already specified");
 455                         if (muxclient_command != 0)
 456                                 fatal("Cannot specify stdio forward with -O");
 457                         if (parse_forward(&fwd, optarg, 1, 0)) {
 458                                 stdio_forward_host = fwd.listen_host;
 459                                 stdio_forward_port = fwd.listen_port;
 460                                 xfree(fwd.connect_host);
 461                         } else {
 462                                 fprintf(stderr,
 463                                     "Bad stdio forwarding specification '%s'\n",
 464                                     optarg);
 465                                 exit(255);
 466                         }
 467                         options.request_tty = REQUEST_TTY_NO;
 468                         no_shell_flag = 1;
 469                         options.clear_forwardings = 1;
 470                         options.exit_on_forward_failure = 1;
 471                         break;
 472                 case 'q':
 473                         options.log_level = SYSLOG_LEVEL_QUIET;
 474                         break;
 475                 case 'e':
 476                         if (optarg[0] == '^' && optarg[2] == 0 &&
 477                             (u_char) optarg[1] >= 64 &&
 478                             (u_char) optarg[1] < 128)
 479                                 options.escape_char = (u_char) optarg[1] & 31;
 480                         else if (strlen(optarg) == 1)
 481                                 options.escape_char = (u_char) optarg[0];
 482                         else if (strcmp(optarg, "none") == 0)
 483                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 484                         else {
 485                                 fprintf(stderr, "Bad escape character '%s'.\n",
 486                                     optarg);
 487                                 exit(255);
 488                         }
 489                         break;
 490                 case 'c':
 491                         if (ciphers_valid(optarg)) {
 492                                 /* SSH2 only */
 493                                 options.ciphers = xstrdup(optarg);
 494                                 options.cipher = SSH_CIPHER_INVALID;
 495                         } else {
 496                                 /* SSH1 only */
 497                                 options.cipher = cipher_number(optarg);
 498                                 if (options.cipher == -1) {
 499                                         fprintf(stderr,
 500                                             "Unknown cipher type '%s'\n",
 501                                             optarg);
 502                                         exit(255);
 503                                 }
 504                                 if (options.cipher == SSH_CIPHER_3DES)
 505                                         options.ciphers = "3des-cbc";
 506                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 507                                         options.ciphers = "blowfish-cbc";
 508                                 else
 509                                         options.ciphers = (char *)-1;
 510                         }
 511                         break;
 512                 case 'm':
 513                         if (mac_valid(optarg))
 514                                 options.macs = xstrdup(optarg);
 515                         else {
 516                                 fprintf(stderr, "Unknown mac type '%s'\n",
 517                                     optarg);
 518                                 exit(255);
 519                         }
 520                         break;
 521                 case 'M':
 522                         if (options.control_master == SSHCTL_MASTER_YES)
 523                                 options.control_master = SSHCTL_MASTER_ASK;
 524                         else
 525                                 options.control_master = SSHCTL_MASTER_YES;
 526                         break;
 527                 case 'p':
 528                         options.port = a2port(optarg);
 529                         if (options.port <= 0) {
 530                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 531                                 exit(255);
 532                         }
 533                         break;
 534                 case 'l':
 535                         options.user = optarg;
 536                         break;
 537
 538                 case 'L':
 539                         if (parse_forward(&fwd, optarg, 0, 0))
 540                                 add_local_forward(&options, &fwd);
 541                         else {
 542                                 fprintf(stderr,
 543                                     "Bad local forwarding specification '%s'\n",
 544                                     optarg);
 545                                 exit(255);
 546                         }
 547                         break;
 548
 549                 case 'R':
 550                         if (parse_forward(&fwd, optarg, 0, 1)) {
 551                                 add_remote_forward(&options, &fwd);
 552                         } else {
 553                                 fprintf(stderr,
 554                                     "Bad remote forwarding specification "
 555                                     "'%s'\n", optarg);
 556                                 exit(255);
 557                         }
 558                         break;
 559
 560                 case 'D':
 561                         if (parse_forward(&fwd, optarg, 1, 0)) {
 562                                 add_local_forward(&options, &fwd);
 563                         } else {
 564                                 fprintf(stderr,
 565                                     "Bad dynamic forwarding specification "
 566                                     "'%s'\n", optarg);
 567                                 exit(255);
 568                         }
 569                         break;
 570
 571                 case 'C':
 572                         options.compression = 1;
 573                         break;
 574                 case 'N':
 575                         no_shell_flag = 1;
 576                         options.request_tty = REQUEST_TTY_NO;
 577                         break;
 578                 case 'T':
 579                         options.request_tty = REQUEST_TTY_NO;
 580                         break;
 581                 case 'o':
 582                         dummy = 1;
 583                         line = xstrdup(optarg);
 584                         if (process_config_line(&options, host ? host : "",
 585                             line, "command-line", 0, &dummy) != 0)
 586                                 exit(255);
 587                         xfree(line);
 588                         break;
 589                 case 's':
 590                         subsystem_flag = 1;
 591                         break;
 592                 case 'S':
 593                         if (options.control_path != NULL)
 594                                 free(options.control_path);
 595                         options.control_path = xstrdup(optarg);
 596                         break;
 597                 case 'b':
 598                         options.bind_address = optarg;
 599                         break;
 600                 case 'F':
 601                         config = optarg;
 602                         break;
 603                 default:
 604                         usage();
 605                 }
 606         }
 607
 608         ac -= optind;
 609         av += optind;
 610
 611         if (ac > 0 && !host) {
 612                 if (strrchr(*av, '@')) {
 613                         p = xstrdup(*av);
 614                         cp = strrchr(p, '@');
 615                         if (cp == NULL || cp == p)
 616                                 usage();
 617                         options.user = p;
 618                         *cp = '\0';
 619                         host = ++cp;
 620                 } else
 621                         host = *av;
 622                 if (ac > 1) {
 623                         optind = optreset = 1;
 624                         goto again;
 625                 }
 626                 ac--, av++;
 627         }
 628
 629         /* Check that we got a host name. */
 630         if (!host)
 631                 usage();
 632
 633         OpenSSL_add_all_algorithms();
 634         ERR_load_crypto_strings();
 635
 636         /* Initialize the command to execute on remote host. */
 637         buffer_init(&command);
 638
 639         if (options.request_tty == REQUEST_TTY_YES ||
 640             options.request_tty == REQUEST_TTY_FORCE)
 641                 tty_flag = 1;
 642
 643         /*
 644          * Save the command to execute on the remote host in a buffer. There
 645          * is no limit on the length of the command, except by the maximum
 646          * packet size.  Also sets the tty flag if there is no command.
 647          */
 648         if (!ac) {
 649                 /* No command specified - execute shell on a tty. */
 650                 tty_flag = options.request_tty != REQUEST_TTY_NO;
 651                 if (subsystem_flag) {
 652                         fprintf(stderr,
 653                             "You must specify a subsystem to invoke.\n");
 654                         usage();
 655                 }
 656         } else {
 657                 /* A command has been specified.  Store it into the buffer. */
 658                 for (i = 0; i < ac; i++) {
 659                         if (i)
 660                                 buffer_append(&command, " ", 1);
 661                         buffer_append(&command, av[i], strlen(av[i]));
 662                 }
 663         }
 664
 665         /* Cannot fork to background if no command. */
 666         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 667             !no_shell_flag)
 668                 fatal("Cannot fork into background without a command "
 669                     "to execute.");
 670
 671         /* Allocate a tty by default if no command specified. */
 672         if (buffer_len(&command) == 0)
 673                 tty_flag = options.request_tty != REQUEST_TTY_NO;
 674
 675         /* Force no tty */
 676         if (options.request_tty == REQUEST_TTY_NO || muxclient_command != 0)
 677                 tty_flag = 0;
 678         /* Do not allocate a tty if stdin is not a tty. */
 679         if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
 680             options.request_tty != REQUEST_TTY_FORCE) {
 681                 if (tty_flag)
 682                         logit("Pseudo-terminal will not be allocated because "
 683                             "stdin is not a terminal.");
 684                 tty_flag = 0;
 685         }
 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         seed_rng();
 723
 724         if (options.user == NULL)
 725                 options.user = xstrdup(pw->pw_name);
 726
 727         /* Get default port if port has not been set. */
 728         if (options.port == 0) {
 729                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 730                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 731         }
 732
 733         /* preserve host name given on command line for %n expansion */
 734         host_arg = host;
 735         if (options.hostname != NULL) {
 736                 host = percent_expand(options.hostname,
 737                     "h", host, (char *)NULL);
 738         }
 739
 740         if (gethostname(thishost, sizeof(thishost)) == -1)
 741                 fatal("gethostname: %s", strerror(errno));
 742         strlcpy(shorthost, thishost, sizeof(shorthost));
 743         shorthost[strcspn(thishost, ".")] = '\0';
 744         snprintf(portstr, sizeof(portstr), "%d", options.port);
 745
 746         if (options.local_command != NULL) {
 747                 debug3("expanding LocalCommand: %s", options.local_command);
 748                 cp = options.local_command;
 749                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 750                     "h", host, "l", thishost, "n", host_arg, "r", options.user,
 751                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 752                     (char *)NULL);
 753                 debug3("expanded LocalCommand: %s", options.local_command);
 754                 xfree(cp);
 755         }
 756
 757         /* force lowercase for hostkey matching */
 758         if (options.host_key_alias != NULL) {
 759                 for (p = options.host_key_alias; *p; p++)
 760                         if (isupper(*p))
 761                                 *p = (char)tolower(*p);
 762         }
 763
 764         if (options.proxy_command != NULL &&
 765             strcmp(options.proxy_command, "none") == 0) {
 766                 xfree(options.proxy_command);
 767                 options.proxy_command = NULL;
 768         }
 769         if (options.control_path != NULL &&
 770             strcmp(options.control_path, "none") == 0) {
 771                 xfree(options.control_path);
 772                 options.control_path = NULL;
 773         }
 774
 775         if (options.control_path != NULL) {
 776                 cp = tilde_expand_filename(options.control_path,
 777                     original_real_uid);
 778                 xfree(options.control_path);
 779                 options.control_path = percent_expand(cp, "h", host,
 780                     "l", thishost, "n", host_arg, "r", options.user,
 781                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 782                     (char *)NULL);
 783                 xfree(cp);
 784         }
 785         if (muxclient_command != 0 && options.control_path == NULL)
 786                 fatal("No ControlPath specified for \"-O\" command");
 787         if (options.control_path != NULL)
 788                 muxclient(options.control_path);
 789
 790         timeout_ms = options.connection_timeout * 1000;
 791
 792         /* Open a connection to the remote host. */
 793         if (ssh_connect(host, &hostaddr, options.port,
 794             options.address_family, options.connection_attempts, &timeout_ms,
 795             options.tcp_keep_alive,
 796 #ifdef HAVE_CYGWIN
 797             options.use_privileged_port,
 798 #else
 799             original_effective_uid == 0 && options.use_privileged_port,
 800 #endif
 801             options.proxy_command) != 0)
 802                 exit(255);
 803
 804         if (timeout_ms > 0)
 805                 debug3("timeout: %d ms remain after connect", timeout_ms);
 806
 807         /*
 808          * If we successfully made the connection, load the host private key
 809          * in case we will need it later for combined rsa-rhosts
 810          * authentication. This must be done before releasing extra
 811          * privileges, because the file is only readable by root.
 812          * If we cannot access the private keys, load the public keys
 813          * instead and try to execute the ssh-keysign helper instead.
 814          */
 815         sensitive_data.nkeys = 0;
 816         sensitive_data.keys = NULL;
 817         sensitive_data.external_keysign = 0;
 818         if (options.rhosts_rsa_authentication ||
 819             options.hostbased_authentication) {
 820                 sensitive_data.nkeys = 7;
 821                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 822                     sizeof(Key));
 823                 for (i = 0; i < sensitive_data.nkeys; i++)
 824                         sensitive_data.keys[i] = NULL;
 825
 826                 PRIV_START;
 827                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 828                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 829                 sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
 830                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 831 #ifdef OPENSSL_HAS_ECC
 832                 sensitive_data.keys[2] = key_load_private_cert(KEY_ECDSA,
 833                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
 834 #endif
 835                 sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
 836                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 837                 sensitive_data.keys[4] = key_load_private_type(KEY_DSA,
 838                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 839 #ifdef OPENSSL_HAS_ECC
 840                 sensitive_data.keys[5] = key_load_private_type(KEY_ECDSA,
 841                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
 842 #endif
 843                 sensitive_data.keys[6] = key_load_private_type(KEY_RSA,
 844                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 845                 PRIV_END;
 846
 847                 if (options.hostbased_authentication == 1 &&
 848                     sensitive_data.keys[0] == NULL &&
 849                     sensitive_data.keys[4] == NULL &&
 850                     sensitive_data.keys[5] == NULL &&
 851                     sensitive_data.keys[6] == NULL) {
 852                         sensitive_data.keys[1] = key_load_cert(
 853                             _PATH_HOST_DSA_KEY_FILE);
 854 #ifdef OPENSSL_HAS_ECC
 855                         sensitive_data.keys[2] = key_load_cert(
 856                             _PATH_HOST_ECDSA_KEY_FILE);
 857 #endif
 858                         sensitive_data.keys[3] = key_load_cert(
 859                             _PATH_HOST_RSA_KEY_FILE);
 860                         sensitive_data.keys[4] = key_load_public(
 861                             _PATH_HOST_DSA_KEY_FILE, NULL);
 862 #ifdef OPENSSL_HAS_ECC
 863                         sensitive_data.keys[5] = key_load_public(
 864                             _PATH_HOST_ECDSA_KEY_FILE, NULL);
 865 #endif
 866                         sensitive_data.keys[6] = key_load_public(
 867                             _PATH_HOST_RSA_KEY_FILE, NULL);
 868                         sensitive_data.external_keysign = 1;
 869                 }
 870         }
 871         /*
 872          * Get rid of any extra privileges that we may have.  We will no
 873          * longer need them.  Also, extra privileges could make it very hard
 874          * to read identity files and other non-world-readable files from the
 875          * user's home directory if it happens to be on a NFS volume where
 876          * root is mapped to nobody.
 877          */
 878         if (original_effective_uid == 0) {
 879                 PRIV_START;
 880                 permanently_set_uid(pw);
 881         }
 882
 883         /*
 884          * Now that we are back to our own permissions, create ~/.ssh
 885          * directory if it doesn't already exist.
 886          */
 887         r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
 888             strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 889         if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
 890 #ifdef WITH_SELINUX
 891                 ssh_selinux_setfscreatecon(buf);
 892 #endif
 893                 if (mkdir(buf, 0700) < 0)
 894                         error("Could not create directory '%.200s'.", buf);
 895 #ifdef WITH_SELINUX
 896                 ssh_selinux_setfscreatecon(NULL);
 897 #endif
 898         }
 899         /* load options.identity_files */
 900         load_public_identity_files();
 901
 902         /* Expand ~ in known host file names. */
 903         tilde_expand_paths(options.system_hostfiles,
 904             options.num_system_hostfiles);
 905         tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
 906
 907         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 908         signal(SIGCHLD, main_sigchld_handler);
 909
 910         /* Log into the remote system.  Never returns if the login fails. */
 911         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 912             options.port, pw, timeout_ms);
 913
 914         if (packet_connection_is_on_socket()) {
 915                 verbose("Authenticated to %s ([%s]:%d).", host,
 916                     get_remote_ipaddr(), get_remote_port());
 917         } else {
 918                 verbose("Authenticated to %s (via proxy).", host);
 919         }
 920
 921         /* We no longer need the private host keys.  Clear them now. */
 922         if (sensitive_data.nkeys != 0) {
 923                 for (i = 0; i < sensitive_data.nkeys; i++) {
 924                         if (sensitive_data.keys[i] != NULL) {
 925                                 /* Destroys contents safely */
 926                                 debug3("clear hostkey %d", i);
 927                                 key_free(sensitive_data.keys[i]);
 928                                 sensitive_data.keys[i] = NULL;
 929                         }
 930                 }
 931                 xfree(sensitive_data.keys);
 932         }
 933         for (i = 0; i < options.num_identity_files; i++) {
 934                 if (options.identity_files[i]) {
 935                         xfree(options.identity_files[i]);
 936                         options.identity_files[i] = NULL;
 937                 }
 938                 if (options.identity_keys[i]) {
 939                         key_free(options.identity_keys[i]);
 940                         options.identity_keys[i] = NULL;
 941                 }
 942         }
 943
 944         exit_status = compat20 ? ssh_session2() : ssh_session();
 945         packet_close();
 946
 947         if (options.control_path != NULL && muxserver_sock != -1)
 948                 unlink(options.control_path);
 949
 950         /* Kill ProxyCommand if it is running. */
 951         ssh_kill_proxy_command();
 952
 953         return exit_status;
 954 }
 955
 956 static void
 957 control_persist_detach(void)
 958 {
 959         pid_t pid;
 960         int devnull;
 961
 962         debug("%s: backgrounding master process", __func__);
 963
 964         /*
 965          * master (current process) into the background, and make the
 966          * foreground process a client of the backgrounded master.
 967          */
 968         switch ((pid = fork())) {
 969         case -1:
 970                 fatal("%s: fork: %s", __func__, strerror(errno));
 971         case 0:
 972                 /* Child: master process continues mainloop */
 973                 break;
 974         default:
 975                 /* Parent: set up mux slave to connect to backgrounded master */
 976                 debug2("%s: background process is %ld", __func__, (long)pid);
 977                 stdin_null_flag = ostdin_null_flag;
 978                 options.request_tty = orequest_tty;
 979                 tty_flag = otty_flag;
 980                 close(muxserver_sock);
 981                 muxserver_sock = -1;
 982                 options.control_master = SSHCTL_MASTER_NO;
 983                 muxclient(options.control_path);
 984                 /* muxclient() doesn't return on success. */
 985                 fatal("Failed to connect to new control master");
 986         }
 987         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
 988                 error("%s: open(\"/dev/null\"): %s", __func__,
 989                     strerror(errno));
 990         } else {
 991                 if (dup2(devnull, STDIN_FILENO) == -1 ||
 992                     dup2(devnull, STDOUT_FILENO) == -1)
 993                         error("%s: dup2: %s", __func__, strerror(errno));
 994                 if (devnull > STDERR_FILENO)
 995                         close(devnull);
 996         }
 997         setproctitle("%s [mux]", options.control_path);
 998 }
 999
1000 /* Do fork() after authentication. Used by "ssh -f" */
1001 static void
1002 fork_postauth(void)
1003 {
1004         if (need_controlpersist_detach)
1005                 control_persist_detach();
1006         debug("forking to background");
1007         fork_after_authentication_flag = 0;
1008         if (daemon(1, 1) < 0)
1009                 fatal("daemon() failed: %.200s", strerror(errno));
1010 }
1011
1012 /* Callback for remote forward global requests */
1013 static void
1014 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
1015 {
1016         Forward *rfwd = (Forward *)ctxt;
1017
1018         /* XXX verbose() on failure? */
1019         debug("remote forward %s for: listen %d, connect %s:%d",
1020             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1021             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
1022         if (type == SSH2_MSG_REQUEST_SUCCESS && rfwd->listen_port == 0) {
1023                 rfwd->allocated_port = packet_get_int();
1024                 logit("Allocated port %u for remote forward to %s:%d",
1025                     rfwd->allocated_port,
1026                     rfwd->connect_host, rfwd->connect_port);
1027         }
1028
1029         if (type == SSH2_MSG_REQUEST_FAILURE) {
1030                 if (options.exit_on_forward_failure)
1031                         fatal("Error: remote port forwarding failed for "
1032                             "listen port %d", rfwd->listen_port);
1033                 else
1034                         logit("Warning: remote port forwarding failed for "
1035                             "listen port %d", rfwd->listen_port);
1036         }
1037         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1038                 debug("All remote forwarding requests processed");
1039                 if (fork_after_authentication_flag)
1040                         fork_postauth();
1041         }
1042 }
1043
1044 static void
1045 client_cleanup_stdio_fwd(int id, void *arg)
1046 {
1047         debug("stdio forwarding: done");
1048         cleanup_exit(0);
1049 }
1050
1051 static int
1052 client_setup_stdio_fwd(const char *host_to_connect, u_short port_to_connect)
1053 {
1054         Channel *c;
1055         int in, out;
1056
1057         debug3("client_setup_stdio_fwd %s:%d", host_to_connect,
1058             port_to_connect);
1059
1060         in = dup(STDIN_FILENO);
1061         out = dup(STDOUT_FILENO);
1062         if (in < 0 || out < 0)
1063                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1064
1065         if ((c = channel_connect_stdio_fwd(host_to_connect, port_to_connect,
1066             in, out)) == NULL)
1067                 return 0;
1068         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1069         return 1;
1070 }
1071
1072 static void
1073 ssh_init_forwarding(void)
1074 {
1075         int success = 0;
1076         int i;
1077
1078         if (stdio_forward_host != NULL) {
1079                 if (!compat20) {
1080                         fatal("stdio forwarding require Protocol 2");
1081                 }
1082                 if (!client_setup_stdio_fwd(stdio_forward_host,
1083                     stdio_forward_port))
1084                         fatal("Failed to connect in stdio forward mode.");
1085         }
1086
1087         /* Initiate local TCP/IP port forwardings. */
1088         for (i = 0; i < options.num_local_forwards; i++) {
1089                 debug("Local connections to %.200s:%d forwarded to remote "
1090                     "address %.200s:%d",
1091                     (options.local_forwards[i].listen_host == NULL) ?
1092                     (options.gateway_ports ? "*" : "LOCALHOST") :
1093                     options.local_forwards[i].listen_host,
1094                     options.local_forwards[i].listen_port,
1095                     options.local_forwards[i].connect_host,
1096                     options.local_forwards[i].connect_port);
1097                 success += channel_setup_local_fwd_listener(
1098                     options.local_forwards[i].listen_host,
1099                     options.local_forwards[i].listen_port,
1100                     options.local_forwards[i].connect_host,
1101                     options.local_forwards[i].connect_port,
1102                     options.gateway_ports);
1103         }
1104         if (i > 0 && success != i && options.exit_on_forward_failure)
1105                 fatal("Could not request local forwarding.");
1106         if (i > 0 && success == 0)
1107                 error("Could not request local forwarding.");
1108
1109         /* Initiate remote TCP/IP port forwardings. */
1110         for (i = 0; i < options.num_remote_forwards; i++) {
1111                 debug("Remote connections from %.200s:%d forwarded to "
1112                     "local address %.200s:%d",
1113                     (options.remote_forwards[i].listen_host == NULL) ?
1114                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1115                     options.remote_forwards[i].listen_port,
1116                     options.remote_forwards[i].connect_host,
1117                     options.remote_forwards[i].connect_port);
1118                 if (channel_request_remote_forwarding(
1119                     options.remote_forwards[i].listen_host,
1120                     options.remote_forwards[i].listen_port,
1121                     options.remote_forwards[i].connect_host,
1122                     options.remote_forwards[i].connect_port) < 0) {
1123                         if (options.exit_on_forward_failure)
1124                                 fatal("Could not request remote forwarding.");
1125                         else
1126                                 logit("Warning: Could not request remote "
1127                                     "forwarding.");
1128                 }
1129                 client_register_global_confirm(ssh_confirm_remote_forward,
1130                     &options.remote_forwards[i]);
1131         }
1132
1133         /* Initiate tunnel forwarding. */
1134         if (options.tun_open != SSH_TUNMODE_NO) {
1135                 if (client_request_tun_fwd(options.tun_open,
1136                     options.tun_local, options.tun_remote) == -1) {
1137                         if (options.exit_on_forward_failure)
1138                                 fatal("Could not request tunnel forwarding.");
1139                         else
1140                                 error("Could not request tunnel forwarding.");
1141                 }
1142         }
1143 }
1144
1145 static void
1146 check_agent_present(void)
1147 {
1148         if (options.forward_agent) {
1149                 /* Clear agent forwarding if we don't have an agent. */
1150                 if (!ssh_agent_present())
1151                         options.forward_agent = 0;
1152         }
1153 }
1154
1155 static int
1156 ssh_session(void)
1157 {
1158         int type;
1159         int interactive = 0;
1160         int have_tty = 0;
1161         struct winsize ws;
1162         char *cp;
1163         const char *display;
1164
1165         /* Enable compression if requested. */
1166         if (options.compression) {
1167                 debug("Requesting compression at level %d.",
1168                     options.compression_level);
1169
1170                 if (options.compression_level < 1 ||
1171                     options.compression_level > 9)
1172                         fatal("Compression level must be from 1 (fast) to "
1173                             "9 (slow, best).");
1174
1175                 /* Send the request. */
1176                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1177                 packet_put_int(options.compression_level);
1178                 packet_send();
1179                 packet_write_wait();
1180                 type = packet_read();
1181                 if (type == SSH_SMSG_SUCCESS)
1182                         packet_start_compression(options.compression_level);
1183                 else if (type == SSH_SMSG_FAILURE)
1184                         logit("Warning: Remote host refused compression.");
1185                 else
1186                         packet_disconnect("Protocol error waiting for "
1187                             "compression response.");
1188         }
1189         /* Allocate a pseudo tty if appropriate. */
1190         if (tty_flag) {
1191                 debug("Requesting pty.");
1192
1193                 /* Start the packet. */
1194                 packet_start(SSH_CMSG_REQUEST_PTY);
1195
1196                 /* Store TERM in the packet.  There is no limit on the
1197                    length of the string. */
1198                 cp = getenv("TERM");
1199                 if (!cp)
1200                         cp = "";
1201                 packet_put_cstring(cp);
1202
1203                 /* Store window size in the packet. */
1204                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1205                         memset(&ws, 0, sizeof(ws));
1206                 packet_put_int((u_int)ws.ws_row);
1207                 packet_put_int((u_int)ws.ws_col);
1208                 packet_put_int((u_int)ws.ws_xpixel);
1209                 packet_put_int((u_int)ws.ws_ypixel);
1210
1211                 /* Store tty modes in the packet. */
1212                 tty_make_modes(fileno(stdin), NULL);
1213
1214                 /* Send the packet, and wait for it to leave. */
1215                 packet_send();
1216                 packet_write_wait();
1217
1218                 /* Read response from the server. */
1219                 type = packet_read();
1220                 if (type == SSH_SMSG_SUCCESS) {
1221                         interactive = 1;
1222                         have_tty = 1;
1223                 } else if (type == SSH_SMSG_FAILURE)
1224                         logit("Warning: Remote host failed or refused to "
1225                             "allocate a pseudo tty.");
1226                 else
1227                         packet_disconnect("Protocol error waiting for pty "
1228                             "request response.");
1229         }
1230         /* Request X11 forwarding if enabled and DISPLAY is set. */
1231         display = getenv("DISPLAY");
1232         if (options.forward_x11 && display != NULL) {
1233                 char *proto, *data;
1234                 /* Get reasonable local authentication information. */
1235                 client_x11_get_proto(display, options.xauth_location,
1236                     options.forward_x11_trusted,
1237                     options.forward_x11_timeout,
1238                     &proto, &data);
1239                 /* Request forwarding with authentication spoofing. */
1240                 debug("Requesting X11 forwarding with authentication "
1241                     "spoofing.");
1242                 x11_request_forwarding_with_spoofing(0, display, proto,
1243                     data, 0);
1244                 /* Read response from the server. */
1245                 type = packet_read();
1246                 if (type == SSH_SMSG_SUCCESS) {
1247                         interactive = 1;
1248                 } else if (type == SSH_SMSG_FAILURE) {
1249                         logit("Warning: Remote host denied X11 forwarding.");
1250                 } else {
1251                         packet_disconnect("Protocol error waiting for X11 "
1252                             "forwarding");
1253                 }
1254         }
1255         /* Tell the packet module whether this is an interactive session. */
1256         packet_set_interactive(interactive,
1257             options.ip_qos_interactive, options.ip_qos_bulk);
1258
1259         /* Request authentication agent forwarding if appropriate. */
1260         check_agent_present();
1261
1262         if (options.forward_agent) {
1263                 debug("Requesting authentication agent forwarding.");
1264                 auth_request_forwarding();
1265
1266                 /* Read response from the server. */
1267                 type = packet_read();
1268                 packet_check_eom();
1269                 if (type != SSH_SMSG_SUCCESS)
1270                         logit("Warning: Remote host denied authentication agent forwarding.");
1271         }
1272
1273         /* Initiate port forwardings. */
1274         ssh_init_forwarding();
1275
1276         /* Execute a local command */
1277         if (options.local_command != NULL &&
1278             options.permit_local_command)
1279                 ssh_local_cmd(options.local_command);
1280
1281         /*
1282          * If requested and we are not interested in replies to remote
1283          * forwarding requests, then let ssh continue in the background.
1284          */
1285         if (fork_after_authentication_flag) {
1286                 if (options.exit_on_forward_failure &&
1287                     options.num_remote_forwards > 0) {
1288                         debug("deferring postauth fork until remote forward "
1289                             "confirmation received");
1290                 } else
1291                         fork_postauth();
1292         }
1293
1294         /*
1295          * If a command was specified on the command line, execute the
1296          * command now. Otherwise request the server to start a shell.
1297          */
1298         if (buffer_len(&command) > 0) {
1299                 int len = buffer_len(&command);
1300                 if (len > 900)
1301                         len = 900;
1302                 debug("Sending command: %.*s", len,
1303                     (u_char *)buffer_ptr(&command));
1304                 packet_start(SSH_CMSG_EXEC_CMD);
1305                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1306                 packet_send();
1307                 packet_write_wait();
1308         } else {
1309                 debug("Requesting shell.");
1310                 packet_start(SSH_CMSG_EXEC_SHELL);
1311                 packet_send();
1312                 packet_write_wait();
1313         }
1314
1315         /* Enter the interactive session. */
1316         return client_loop(have_tty, tty_flag ?
1317             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1318 }
1319
1320 /* request pty/x11/agent/tcpfwd/shell for channel */
1321 static void
1322 ssh_session2_setup(int id, int success, void *arg)
1323 {
1324         extern char **environ;
1325         const char *display;
1326         int interactive = tty_flag;
1327
1328         if (!success)
1329                 return; /* No need for error message, channels code sens one */
1330
1331         display = getenv("DISPLAY");
1332         if (options.forward_x11 && display != NULL) {
1333                 char *proto, *data;
1334                 /* Get reasonable local authentication information. */
1335                 client_x11_get_proto(display, options.xauth_location,
1336                     options.forward_x11_trusted,
1337                     options.forward_x11_timeout, &proto, &data);
1338                 /* Request forwarding with authentication spoofing. */
1339                 debug("Requesting X11 forwarding with authentication "
1340                     "spoofing.");
1341                 x11_request_forwarding_with_spoofing(id, display, proto,
1342                     data, 1);
1343                 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
1344                 /* XXX exit_on_forward_failure */
1345                 interactive = 1;
1346         }
1347
1348         check_agent_present();
1349         if (options.forward_agent) {
1350                 debug("Requesting authentication agent forwarding.");
1351                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1352                 packet_send();
1353         }
1354
1355         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1356             NULL, fileno(stdin), &command, environ);
1357 }
1358
1359 /* open new channel for a session */
1360 static int
1361 ssh_session2_open(void)
1362 {
1363         Channel *c;
1364         int window, packetmax, in, out, err;
1365
1366         if (stdin_null_flag) {
1367                 in = open(_PATH_DEVNULL, O_RDONLY);
1368         } else {
1369                 in = dup(STDIN_FILENO);
1370         }
1371         out = dup(STDOUT_FILENO);
1372         err = dup(STDERR_FILENO);
1373
1374         if (in < 0 || out < 0 || err < 0)
1375                 fatal("dup() in/out/err failed");
1376
1377         /* enable nonblocking unless tty */
1378         if (!isatty(in))
1379                 set_nonblock(in);
1380         if (!isatty(out))
1381                 set_nonblock(out);
1382         if (!isatty(err))
1383                 set_nonblock(err);
1384
1385         window = CHAN_SES_WINDOW_DEFAULT;
1386         packetmax = CHAN_SES_PACKET_DEFAULT;
1387         if (tty_flag) {
1388                 window >>= 1;
1389                 packetmax >>= 1;
1390         }
1391         c = channel_new(
1392             "session", SSH_CHANNEL_OPENING, in, out, err,
1393             window, packetmax, CHAN_EXTENDED_WRITE,
1394             "client-session", /*nonblock*/0);
1395
1396         debug3("ssh_session2_open: channel_new: %d", c->self);
1397
1398         channel_send_open(c->self);
1399         if (!no_shell_flag)
1400                 channel_register_open_confirm(c->self,
1401                     ssh_session2_setup, NULL);
1402
1403         return c->self;
1404 }
1405
1406 static int
1407 ssh_session2(void)
1408 {
1409         int id = -1;
1410
1411         /* XXX should be pre-session */
1412         ssh_init_forwarding();
1413
1414         /* Start listening for multiplex clients */
1415         muxserver_listen();
1416
1417         /*
1418          * If we are in control persist mode, then prepare to background
1419          * ourselves and have a foreground client attach as a control
1420          * slave. NB. we must save copies of the flags that we override for
1421          * the backgrounding, since we defer attachment of the slave until
1422          * after the connection is fully established (in particular,
1423          * async rfwd replies have been received for ExitOnForwardFailure).
1424          */
1425         if (options.control_persist && muxserver_sock != -1) {
1426                 ostdin_null_flag = stdin_null_flag;
1427                 ono_shell_flag = no_shell_flag;
1428                 orequest_tty = options.request_tty;
1429                 otty_flag = tty_flag;
1430                 stdin_null_flag = 1;
1431                 no_shell_flag = 1;
1432                 tty_flag = 0;
1433                 if (!fork_after_authentication_flag)
1434                         need_controlpersist_detach = 1;
1435                 fork_after_authentication_flag = 1;
1436         }
1437
1438         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1439                 id = ssh_session2_open();
1440
1441         /* If we don't expect to open a new session, then disallow it */
1442         if (options.control_master == SSHCTL_MASTER_NO &&
1443             (datafellows & SSH_NEW_OPENSSH)) {
1444                 debug("Requesting no-more-sessions@openssh.com");
1445                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1446                 packet_put_cstring("no-more-sessions@openssh.com");
1447                 packet_put_char(0);
1448                 packet_send();
1449         }
1450
1451         /* Execute a local command */
1452         if (options.local_command != NULL &&
1453             options.permit_local_command)
1454                 ssh_local_cmd(options.local_command);
1455
1456         /*
1457          * If requested and we are not interested in replies to remote
1458          * forwarding requests, then let ssh continue in the background.
1459          */
1460         if (fork_after_authentication_flag) {
1461                 if (options.exit_on_forward_failure &&
1462                     options.num_remote_forwards > 0) {
1463                         debug("deferring postauth fork until remote forward "
1464                             "confirmation received");
1465                 } else
1466                         fork_postauth();
1467         }
1468
1469         if (options.use_roaming)
1470                 request_roaming();
1471
1472         return client_loop(tty_flag, tty_flag ?
1473             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1474 }
1475
1476 static void
1477 load_public_identity_files(void)
1478 {
1479         char *filename, *cp, thishost[NI_MAXHOST];
1480         char *pwdir = NULL, *pwname = NULL;
1481         int i = 0;
1482         Key *public;
1483         struct passwd *pw;
1484         u_int n_ids;
1485         char *identity_files[SSH_MAX_IDENTITY_FILES];
1486         Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1487 #ifdef ENABLE_PKCS11
1488         Key **keys;
1489         int nkeys;
1490 #endif /* PKCS11 */
1491
1492         n_ids = 0;
1493         bzero(identity_files, sizeof(identity_files));
1494         bzero(identity_keys, sizeof(identity_keys));
1495
1496 #ifdef ENABLE_PKCS11
1497         if (options.pkcs11_provider != NULL &&
1498             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1499             (pkcs11_init(!options.batch_mode) == 0) &&
1500             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1501             &keys)) > 0) {
1502                 for (i = 0; i < nkeys; i++) {
1503                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1504                                 key_free(keys[i]);
1505                                 continue;
1506                         }
1507                         identity_keys[n_ids] = keys[i];
1508                         identity_files[n_ids] =
1509                             xstrdup(options.pkcs11_provider); /* XXX */
1510                         n_ids++;
1511                 }
1512                 xfree(keys);
1513         }
1514 #endif /* ENABLE_PKCS11 */
1515         if ((pw = getpwuid(original_real_uid)) == NULL)
1516                 fatal("load_public_identity_files: getpwuid failed");
1517         pwname = xstrdup(pw->pw_name);
1518         pwdir = xstrdup(pw->pw_dir);
1519         if (gethostname(thishost, sizeof(thishost)) == -1)
1520                 fatal("load_public_identity_files: gethostname: %s",
1521                     strerror(errno));
1522         for (i = 0; i < options.num_identity_files; i++) {
1523                 if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1524                         xfree(options.identity_files[i]);
1525                         continue;
1526                 }
1527                 cp = tilde_expand_filename(options.identity_files[i],
1528                     original_real_uid);
1529                 filename = percent_expand(cp, "d", pwdir,
1530                     "u", pwname, "l", thishost, "h", host,
1531                     "r", options.user, (char *)NULL);
1532                 xfree(cp);
1533                 public = key_load_public(filename, NULL);
1534                 debug("identity file %s type %d", filename,
1535                     public ? public->type : -1);
1536                 xfree(options.identity_files[i]);
1537                 identity_files[n_ids] = filename;
1538                 identity_keys[n_ids] = public;
1539
1540                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
1541                         continue;
1542
1543                 /* Try to add the certificate variant too */
1544                 xasprintf(&cp, "%s-cert", filename);
1545                 public = key_load_public(cp, NULL);
1546                 debug("identity file %s type %d", cp,
1547                     public ? public->type : -1);
1548                 if (public == NULL) {
1549                         xfree(cp);
1550                         continue;
1551                 }
1552                 if (!key_is_cert(public)) {
1553                         debug("%s: key %s type %s is not a certificate",
1554                             __func__, cp, key_type(public));
1555                         key_free(public);
1556                         xfree(cp);
1557                         continue;
1558                 }
1559                 identity_keys[n_ids] = public;
1560                 /* point to the original path, most likely the private key */
1561                 identity_files[n_ids] = xstrdup(filename);
1562                 n_ids++;
1563         }
1564         options.num_identity_files = n_ids;
1565         memcpy(options.identity_files, identity_files, sizeof(identity_files));
1566         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
1567
1568         bzero(pwname, strlen(pwname));
1569         xfree(pwname);
1570         bzero(pwdir, strlen(pwdir));
1571         xfree(pwdir);
1572 }
1573
1574 static void
1575 main_sigchld_handler(int sig)
1576 {
1577         int save_errno = errno;
1578         pid_t pid;
1579         int status;
1580
1581         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
1582             (pid < 0 && errno == EINTR))
1583                 ;
1584
1585         signal(sig, main_sigchld_handler);
1586         errno = save_errno;
1587 }
1588