crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.356 2011/01/06 22:23:53 djm Exp $ */
   2 /* $FreeBSD$ */
   3 /*
   4  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   5  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   6  *                    All rights reserved
   7  * Ssh client program.  This program can be used to log into a remote machine.
   8  * The software supports strong authentication, encryption, and forwarding
   9  * of X11, TCP/IP, and authentication connections.
  10  *
  11  * As far as I am concerned, the code I have written for this software
  12  * can be used freely for any purpose.  Any derived versions of this
  13  * software must be clearly marked as such, and if the derived work is
  14  * incompatible with the protocol description in the RFC file, it must be
  15  * called by a name other than "ssh" or "Secure Shell".
  16  *
  17  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  18  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  19  *
  20  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  21  * in Canada (German citizen).
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the above copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  *
  32  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  33  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  34  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  35  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  36  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  37  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  38  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  39  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  40  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  41  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  42  */
  43
  44 #include "includes.h"
  45 __RCSID("$FreeBSD$");
  46
  47 #include <sys/types.h>
  48 #ifdef HAVE_SYS_STAT_H
  49 # include <sys/stat.h>
  50 #endif
  51 #include <sys/resource.h>
  52 #include <sys/ioctl.h>
  53 #include <sys/param.h>
  54 #include <sys/socket.h>
  55 #include <sys/wait.h>
  56
  57 #include <ctype.h>
  58 #include <errno.h>
  59 #include <fcntl.h>
  60 #include <netdb.h>
  61 #ifdef HAVE_PATHS_H
  62 #include <paths.h>
  63 #endif
  64 #include <pwd.h>
  65 #include <signal.h>
  66 #include <stdarg.h>
  67 #include <stddef.h>
  68 #include <stdio.h>
  69 #include <stdlib.h>
  70 #include <string.h>
  71 #include <unistd.h>
  72
  73 #include <netinet/in.h>
  74 #include <arpa/inet.h>
  75
  76 #include <openssl/evp.h>
  77 #include <openssl/err.h>
  78 #include "openbsd-compat/openssl-compat.h"
  79 #include "openbsd-compat/sys-queue.h"
  80
  81 #include "xmalloc.h"
  82 #include "ssh.h"
  83 #include "ssh1.h"
  84 #include "ssh2.h"
  85 #include "canohost.h"
  86 #include "compat.h"
  87 #include "cipher.h"
  88 #include "packet.h"
  89 #include "buffer.h"
  90 #include "channels.h"
  91 #include "key.h"
  92 #include "authfd.h"
  93 #include "authfile.h"
  94 #include "pathnames.h"
  95 #include "dispatch.h"
  96 #include "clientloop.h"
  97 #include "log.h"
  98 #include "readconf.h"
  99 #include "sshconnect.h"
 100 #include "misc.h"
 101 #include "kex.h"
 102 #include "mac.h"
 103 #include "sshpty.h"
 104 #include "match.h"
 105 #include "msg.h"
 106 #include "uidswap.h"
 107 #include "roaming.h"
 108 #include "version.h"
 109
 110 #ifdef ENABLE_PKCS11
 111 #include "ssh-pkcs11.h"
 112 #endif
 113
 114 extern char *__progname;
 115
 116 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 117 int debug_flag = 0;
 118
 119 /* Flag indicating whether a tty should be allocated */
 120 int tty_flag = 0;
 121 int no_tty_flag = 0;
 122 int force_tty_flag = 0;
 123
 124 /* don't exec a shell */
 125 int no_shell_flag = 0;
 126
 127 /*
 128  * Flag indicating that nothing should be read from stdin.  This can be set
 129  * on the command line.
 130  */
 131 int stdin_null_flag = 0;
 132
 133 /*
 134  * Flag indicating that the current process should be backgrounded and
 135  * a new slave launched in the foreground for ControlPersist.
 136  */
 137 int need_controlpersist_detach = 0;
 138
 139 /* Copies of flags for ControlPersist foreground slave */
 140 int ostdin_null_flag, ono_shell_flag, ono_tty_flag, otty_flag;
 141
 142 /*
 143  * Flag indicating that ssh should fork after authentication.  This is useful
 144  * so that the passphrase can be entered manually, and then ssh goes to the
 145  * background.
 146  */
 147 int fork_after_authentication_flag = 0;
 148
 149 /* forward stdio to remote host and port */
 150 char *stdio_forward_host = NULL;
 151 int stdio_forward_port = 0;
 152
 153 /*
 154  * General data structure for command line options and options configurable
 155  * in configuration files.  See readconf.h.
 156  */
 157 Options options;
 158
 159 /* optional user configfile */
 160 char *config = NULL;
 161
 162 /*
 163  * Name of the host we are connecting to.  This is the name given on the
 164  * command line, or the HostName specified for the user-supplied name in a
 165  * configuration file.
 166  */
 167 char *host;
 168
 169 /* socket address the host resolves to */
 170 struct sockaddr_storage hostaddr;
 171
 172 /* Private host keys. */
 173 Sensitive sensitive_data;
 174
 175 /* Original real UID. */
 176 uid_t original_real_uid;
 177 uid_t original_effective_uid;
 178
 179 /* command to be executed */
 180 Buffer command;
 181
 182 /* Should we execute a command or invoke a subsystem? */
 183 int subsystem_flag = 0;
 184
 185 /* # of replies received for global requests */
 186 static int remote_forward_confirms_received = 0;
 187
 188 /* mux.c */
 189 extern int muxserver_sock;
 190 extern u_int muxclient_command;
 191
 192 /* Prints a help message to the user.  This function never returns. */
 193
 194 static void
 195 usage(void)
 196 {
 197         fprintf(stderr,
 198 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
 199 "           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
 200 "           [-I pkcs11] [-i identity_file]\n"
 201 "           [-L [bind_address:]port:host:hostport]\n"
 202 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 203 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 204 "           [-W host:port] [-w local_tun[:remote_tun]]\n"
 205 "           [user@]hostname [command]\n"
 206         );
 207         exit(255);
 208 }
 209
 210 static int ssh_session(void);
 211 static int ssh_session2(void);
 212 static void load_public_identity_files(void);
 213 static void main_sigchld_handler(int);
 214
 215 /* from muxclient.c */
 216 void muxclient(const char *);
 217 void muxserver_listen(void);
 218
 219 /*
 220  * Main program for the ssh client.
 221  */
 222 int
 223 main(int ac, char **av)
 224 {
 225         int i, r, opt, exit_status, use_syslog;
 226         char *p, *cp, *line, *argv0, buf[MAXPATHLEN], *host_arg;
 227         struct stat st;
 228         struct passwd *pw;
 229         int dummy, timeout_ms;
 230         extern int optind, optreset;
 231         extern char *optarg;
 232         struct servent *sp;
 233         Forward fwd;
 234
 235         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 236         sanitise_stdfd();
 237
 238         __progname = ssh_get_progname(av[0]);
 239         init_rng();
 240
 241         /*
 242          * Discard other fds that are hanging around. These can cause problem
 243          * with backgrounded ssh processes started by ControlPersist.
 244          */
 245         closefrom(STDERR_FILENO + 1);
 246
 247         /*
 248          * Save the original real uid.  It will be needed later (uid-swapping
 249          * may clobber the real uid).
 250          */
 251         original_real_uid = getuid();
 252         original_effective_uid = geteuid();
 253
 254         /*
 255          * Use uid-swapping to give up root privileges for the duration of
 256          * option processing.  We will re-instantiate the rights when we are
 257          * ready to create the privileged port, and will permanently drop
 258          * them when the port has been created (actually, when the connection
 259          * has been made, as we may need to create the port several times).
 260          */
 261         PRIV_END;
 262
 263 #ifdef HAVE_SETRLIMIT
 264         /* If we are installed setuid root be careful to not drop core. */
 265         if (original_real_uid != original_effective_uid) {
 266                 struct rlimit rlim;
 267                 rlim.rlim_cur = rlim.rlim_max = 0;
 268                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 269                         fatal("setrlimit failed: %.100s", strerror(errno));
 270         }
 271 #endif
 272         /* Get user data. */
 273         pw = getpwuid(original_real_uid);
 274         if (!pw) {
 275                 logit("You don't exist, go away!");
 276                 exit(255);
 277         }
 278         /* Take a copy of the returned structure. */
 279         pw = pwcopy(pw);
 280
 281         /*
 282          * Set our umask to something reasonable, as some files are created
 283          * with the default umask.  This will make them world-readable but
 284          * writable only by the owner, which is ok for all files for which we
 285          * don't set the modes explicitly.
 286          */
 287         umask(022);
 288
 289         /*
 290          * Initialize option structure to indicate that no values have been
 291          * set.
 292          */
 293         initialize_options(&options);
 294
 295         /* Parse command-line arguments. */
 296         host = NULL;
 297         use_syslog = 0;
 298         argv0 = av[0];
 299
 300  again:
 301         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 302             "ACD:F:I:KL:MNO:PR:S:TVw:W:XYy")) != -1) {
 303                 switch (opt) {
 304                 case '1':
 305                         options.protocol = SSH_PROTO_1;
 306                         break;
 307                 case '2':
 308                         options.protocol = SSH_PROTO_2;
 309                         break;
 310                 case '4':
 311                         options.address_family = AF_INET;
 312                         break;
 313                 case '6':
 314                         options.address_family = AF_INET6;
 315                         break;
 316                 case 'n':
 317                         stdin_null_flag = 1;
 318                         break;
 319                 case 'f':
 320                         fork_after_authentication_flag = 1;
 321                         stdin_null_flag = 1;
 322                         break;
 323                 case 'x':
 324                         options.forward_x11 = 0;
 325                         break;
 326                 case 'X':
 327                         options.forward_x11 = 1;
 328                         break;
 329                 case 'y':
 330                         use_syslog = 1;
 331                         break;
 332                 case 'Y':
 333                         options.forward_x11 = 1;
 334                         options.forward_x11_trusted = 1;
 335                         break;
 336                 case 'g':
 337                         options.gateway_ports = 1;
 338                         break;
 339                 case 'O':
 340                         if (stdio_forward_host != NULL)
 341                                 fatal("Cannot specify multiplexing "
 342                                     "command with -W");
 343                         else if (muxclient_command != 0)
 344                                 fatal("Multiplexing command already specified");
 345                         if (strcmp(optarg, "check") == 0)
 346                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 347                         else if (strcmp(optarg, "forward") == 0)
 348                                 muxclient_command = SSHMUX_COMMAND_FORWARD;
 349                         else if (strcmp(optarg, "exit") == 0)
 350                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 351                         else
 352                                 fatal("Invalid multiplex command.");
 353                         break;
 354                 case 'P':       /* deprecated */
 355                         options.use_privileged_port = 0;
 356                         break;
 357                 case 'a':
 358                         options.forward_agent = 0;
 359                         break;
 360                 case 'A':
 361                         options.forward_agent = 1;
 362                         break;
 363                 case 'k':
 364                         options.gss_deleg_creds = 0;
 365                         break;
 366                 case 'K':
 367                         options.gss_authentication = 1;
 368                         options.gss_deleg_creds = 1;
 369                         break;
 370                 case 'i':
 371                         if (stat(optarg, &st) < 0) {
 372                                 fprintf(stderr, "Warning: Identity file %s "
 373                                     "not accessible: %s.\n", optarg,
 374                                     strerror(errno));
 375                                 break;
 376                         }
 377                         if (options.num_identity_files >=
 378                             SSH_MAX_IDENTITY_FILES)
 379                                 fatal("Too many identity files specified "
 380                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 381                         options.identity_files[options.num_identity_files++] =
 382                             xstrdup(optarg);
 383                         break;
 384                 case 'I':
 385 #ifdef ENABLE_PKCS11
 386                         options.pkcs11_provider = xstrdup(optarg);
 387 #else
 388                         fprintf(stderr, "no support for PKCS#11.\n");
 389 #endif
 390                         break;
 391                 case 't':
 392                         if (tty_flag)
 393                                 force_tty_flag = 1;
 394                         tty_flag = 1;
 395                         break;
 396                 case 'v':
 397                         if (debug_flag == 0) {
 398                                 debug_flag = 1;
 399                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 400                         } else {
 401                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 402                                         options.log_level++;
 403                                 break;
 404                         }
 405                         /* FALLTHROUGH */
 406                 case 'V':
 407                         fprintf(stderr, "%s, %s\n",
 408                             SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 409                         if (opt == 'V')
 410                                 exit(0);
 411                         break;
 412                 case 'w':
 413                         if (options.tun_open == -1)
 414                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 415                         options.tun_local = a2tun(optarg, &options.tun_remote);
 416                         if (options.tun_local == SSH_TUNID_ERR) {
 417                                 fprintf(stderr,
 418                                     "Bad tun device '%s'\n", optarg);
 419                                 exit(255);
 420                         }
 421                         break;
 422                 case 'W':
 423                         if (stdio_forward_host != NULL)
 424                                 fatal("stdio forward already specified");
 425                         if (muxclient_command != 0)
 426                                 fatal("Cannot specify stdio forward with -O");
 427                         if (parse_forward(&fwd, optarg, 1, 0)) {
 428                                 stdio_forward_host = fwd.listen_host;
 429                                 stdio_forward_port = fwd.listen_port;
 430                                 xfree(fwd.connect_host);
 431                         } else {
 432                                 fprintf(stderr,
 433                                     "Bad stdio forwarding specification '%s'\n",
 434                                     optarg);
 435                                 exit(255);
 436                         }
 437                         no_tty_flag = 1;
 438                         no_shell_flag = 1;
 439                         options.clear_forwardings = 1;
 440                         options.exit_on_forward_failure = 1;
 441                         break;
 442                 case 'q':
 443                         options.log_level = SYSLOG_LEVEL_QUIET;
 444                         break;
 445                 case 'e':
 446                         if (optarg[0] == '^' && optarg[2] == 0 &&
 447                             (u_char) optarg[1] >= 64 &&
 448                             (u_char) optarg[1] < 128)
 449                                 options.escape_char = (u_char) optarg[1] & 31;
 450                         else if (strlen(optarg) == 1)
 451                                 options.escape_char = (u_char) optarg[0];
 452                         else if (strcmp(optarg, "none") == 0)
 453                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 454                         else {
 455                                 fprintf(stderr, "Bad escape character '%s'.\n",
 456                                     optarg);
 457                                 exit(255);
 458                         }
 459                         break;
 460                 case 'c':
 461                         if (ciphers_valid(optarg)) {
 462                                 /* SSH2 only */
 463                                 options.ciphers = xstrdup(optarg);
 464                                 options.cipher = SSH_CIPHER_INVALID;
 465                         } else {
 466                                 /* SSH1 only */
 467                                 options.cipher = cipher_number(optarg);
 468                                 if (options.cipher == -1) {
 469                                         fprintf(stderr,
 470                                             "Unknown cipher type '%s'\n",
 471                                             optarg);
 472                                         exit(255);
 473                                 }
 474                                 if (options.cipher == SSH_CIPHER_3DES)
 475                                         options.ciphers = "3des-cbc";
 476                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 477                                         options.ciphers = "blowfish-cbc";
 478                                 else
 479                                         options.ciphers = (char *)-1;
 480                         }
 481                         break;
 482                 case 'm':
 483                         if (mac_valid(optarg))
 484                                 options.macs = xstrdup(optarg);
 485                         else {
 486                                 fprintf(stderr, "Unknown mac type '%s'\n",
 487                                     optarg);
 488                                 exit(255);
 489                         }
 490                         break;
 491                 case 'M':
 492                         if (options.control_master == SSHCTL_MASTER_YES)
 493                                 options.control_master = SSHCTL_MASTER_ASK;
 494                         else
 495                                 options.control_master = SSHCTL_MASTER_YES;
 496                         break;
 497                 case 'p':
 498                         options.port = a2port(optarg);
 499                         if (options.port <= 0) {
 500                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 501                                 exit(255);
 502                         }
 503                         break;
 504                 case 'l':
 505                         options.user = optarg;
 506                         break;
 507
 508                 case 'L':
 509                         if (parse_forward(&fwd, optarg, 0, 0))
 510                                 add_local_forward(&options, &fwd);
 511                         else {
 512                                 fprintf(stderr,
 513                                     "Bad local forwarding specification '%s'\n",
 514                                     optarg);
 515                                 exit(255);
 516                         }
 517                         break;
 518
 519                 case 'R':
 520                         if (parse_forward(&fwd, optarg, 0, 1)) {
 521                                 add_remote_forward(&options, &fwd);
 522                         } else {
 523                                 fprintf(stderr,
 524                                     "Bad remote forwarding specification "
 525                                     "'%s'\n", optarg);
 526                                 exit(255);
 527                         }
 528                         break;
 529
 530                 case 'D':
 531                         if (parse_forward(&fwd, optarg, 1, 0)) {
 532                                 add_local_forward(&options, &fwd);
 533                         } else {
 534                                 fprintf(stderr,
 535                                     "Bad dynamic forwarding specification "
 536                                     "'%s'\n", optarg);
 537                                 exit(255);
 538                         }
 539                         break;
 540
 541                 case 'C':
 542                         options.compression = 1;
 543                         break;
 544                 case 'N':
 545                         no_shell_flag = 1;
 546                         no_tty_flag = 1;
 547                         break;
 548                 case 'T':
 549                         no_tty_flag = 1;
 550 #ifdef  NONE_CIPHER_ENABLED
 551                         /*
 552                          * Ensure that the user does not try to backdoor a
 553                          * NONE cipher switch on an interactive session by
 554                          * explicitly disabling it if the user asks for a
 555                          * session without a tty.
 556                          */
 557                         options.none_switch = 0;
 558 #endif
 559                         break;
 560                 case 'o':
 561                         dummy = 1;
 562                         line = xstrdup(optarg);
 563                         if (process_config_line(&options, host ? host : "",
 564                             line, "command-line", 0, &dummy) != 0)
 565                                 exit(255);
 566                         xfree(line);
 567                         break;
 568                 case 's':
 569                         subsystem_flag = 1;
 570                         break;
 571                 case 'S':
 572                         if (options.control_path != NULL)
 573                                 free(options.control_path);
 574                         options.control_path = xstrdup(optarg);
 575                         break;
 576                 case 'b':
 577                         options.bind_address = optarg;
 578                         break;
 579                 case 'F':
 580                         config = optarg;
 581                         break;
 582                 default:
 583                         usage();
 584                 }
 585         }
 586
 587         ac -= optind;
 588         av += optind;
 589
 590         if (ac > 0 && !host) {
 591                 if (strrchr(*av, '@')) {
 592                         p = xstrdup(*av);
 593                         cp = strrchr(p, '@');
 594                         if (cp == NULL || cp == p)
 595                                 usage();
 596                         options.user = p;
 597                         *cp = '\0';
 598                         host = ++cp;
 599                 } else
 600                         host = *av;
 601                 if (ac > 1) {
 602                         optind = optreset = 1;
 603                         goto again;
 604                 }
 605                 ac--, av++;
 606         }
 607
 608         /* Check that we got a host name. */
 609         if (!host)
 610                 usage();
 611
 612         OpenSSL_add_all_algorithms();
 613         ERR_load_crypto_strings();
 614
 615         /* Initialize the command to execute on remote host. */
 616         buffer_init(&command);
 617
 618         /*
 619          * Save the command to execute on the remote host in a buffer. There
 620          * is no limit on the length of the command, except by the maximum
 621          * packet size.  Also sets the tty flag if there is no command.
 622          */
 623         if (!ac) {
 624                 /* No command specified - execute shell on a tty. */
 625                 tty_flag = 1;
 626                 if (subsystem_flag) {
 627                         fprintf(stderr,
 628                             "You must specify a subsystem to invoke.\n");
 629                         usage();
 630                 }
 631         } else {
 632                 /* A command has been specified.  Store it into the buffer. */
 633                 for (i = 0; i < ac; i++) {
 634                         if (i)
 635                                 buffer_append(&command, " ", 1);
 636                         buffer_append(&command, av[i], strlen(av[i]));
 637                 }
 638         }
 639
 640         /* Cannot fork to background if no command. */
 641         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 642             !no_shell_flag)
 643                 fatal("Cannot fork into background without a command "
 644                     "to execute.");
 645
 646         /* Allocate a tty by default if no command specified. */
 647         if (buffer_len(&command) == 0)
 648                 tty_flag = 1;
 649
 650         /* Force no tty */
 651         if (no_tty_flag || muxclient_command != 0)
 652                 tty_flag = 0;
 653         /* Do not allocate a tty if stdin is not a tty. */
 654         if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
 655                 if (tty_flag)
 656                         logit("Pseudo-terminal will not be allocated because "
 657                             "stdin is not a terminal.");
 658                 tty_flag = 0;
 659         }
 660
 661         /*
 662          * Initialize "log" output.  Since we are the client all output
 663          * actually goes to stderr.
 664          */
 665         log_init(argv0,
 666             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 667             SYSLOG_FACILITY_USER, !use_syslog);
 668
 669         /*
 670          * Read per-user configuration file.  Ignore the system wide config
 671          * file if the user specifies a config file on the command line.
 672          */
 673         if (config != NULL) {
 674                 if (!read_config_file(config, host, &options, 0))
 675                         fatal("Can't open user config file %.100s: "
 676                             "%.100s", config, strerror(errno));
 677         } else {
 678                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 679                     _PATH_SSH_USER_CONFFILE);
 680                 if (r > 0 && (size_t)r < sizeof(buf))
 681                         (void)read_config_file(buf, host, &options, 1);
 682
 683                 /* Read systemwide configuration file after use config. */
 684                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 685                     &options, 0);
 686         }
 687
 688         /* Fill configuration defaults. */
 689         fill_default_options(&options);
 690
 691         channel_set_af(options.address_family);
 692
 693         /* reinit */
 694         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 695
 696         seed_rng();
 697
 698         if (options.user == NULL)
 699                 options.user = xstrdup(pw->pw_name);
 700
 701         /* Get default port if port has not been set. */
 702         if (options.port == 0) {
 703                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 704                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 705         }
 706
 707         /* preserve host name given on command line for %n expansion */
 708         host_arg = host;
 709         if (options.hostname != NULL) {
 710                 host = percent_expand(options.hostname,
 711                     "h", host, (char *)NULL);
 712         }
 713
 714         if (options.local_command != NULL) {
 715                 char thishost[NI_MAXHOST];
 716
 717                 if (gethostname(thishost, sizeof(thishost)) == -1)
 718                         fatal("gethostname: %s", strerror(errno));
 719                 snprintf(buf, sizeof(buf), "%d", options.port);
 720                 debug3("expanding LocalCommand: %s", options.local_command);
 721                 cp = options.local_command;
 722                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 723                     "h", host, "l", thishost, "n", host_arg, "r", options.user,
 724                     "p", buf, "u", pw->pw_name, (char *)NULL);
 725                 debug3("expanded LocalCommand: %s", options.local_command);
 726                 xfree(cp);
 727         }
 728
 729         /* Find canonic host name. */
 730         if (strchr(host, '.') == 0) {
 731                 struct addrinfo hints;
 732                 struct addrinfo *ai = NULL;
 733                 int errgai;
 734                 memset(&hints, 0, sizeof(hints));
 735                 hints.ai_family = options.address_family;
 736                 hints.ai_flags = AI_CANONNAME;
 737                 hints.ai_socktype = SOCK_STREAM;
 738                 errgai = getaddrinfo(host, NULL, &hints, &ai);
 739                 if (errgai == 0) {
 740                         if (ai->ai_canonname != NULL)
 741                                 host = xstrdup(ai->ai_canonname);
 742                         freeaddrinfo(ai);
 743                 }
 744         }
 745
 746         /* force lowercase for hostkey matching */
 747         if (options.host_key_alias != NULL) {
 748                 for (p = options.host_key_alias; *p; p++)
 749                         if (isupper(*p))
 750                                 *p = (char)tolower(*p);
 751         }
 752
 753         if (options.proxy_command != NULL &&
 754             strcmp(options.proxy_command, "none") == 0) {
 755                 xfree(options.proxy_command);
 756                 options.proxy_command = NULL;
 757         }
 758         if (options.control_path != NULL &&
 759             strcmp(options.control_path, "none") == 0) {
 760                 xfree(options.control_path);
 761                 options.control_path = NULL;
 762         }
 763
 764         if (options.control_path != NULL) {
 765                 char thishost[NI_MAXHOST];
 766
 767                 if (gethostname(thishost, sizeof(thishost)) == -1)
 768                         fatal("gethostname: %s", strerror(errno));
 769                 snprintf(buf, sizeof(buf), "%d", options.port);
 770                 cp = tilde_expand_filename(options.control_path,
 771                     original_real_uid);
 772                 xfree(options.control_path);
 773                 options.control_path = percent_expand(cp, "p", buf, "h", host,
 774                     "r", options.user, "l", thishost, (char *)NULL);
 775                 xfree(cp);
 776         }
 777         if (muxclient_command != 0 && options.control_path == NULL)
 778                 fatal("No ControlPath specified for \"-O\" command");
 779         if (options.control_path != NULL)
 780                 muxclient(options.control_path);
 781
 782         timeout_ms = options.connection_timeout * 1000;
 783
 784         /* Open a connection to the remote host. */
 785         if (ssh_connect(host, &hostaddr, options.port,
 786             options.address_family, options.connection_attempts, &timeout_ms,
 787             options.tcp_keep_alive,
 788 #ifdef HAVE_CYGWIN
 789             options.use_privileged_port,
 790 #else
 791             original_effective_uid == 0 && options.use_privileged_port,
 792 #endif
 793             options.proxy_command) != 0)
 794                 exit(255);
 795
 796         if (timeout_ms > 0)
 797                 debug3("timeout: %d ms remain after connect", timeout_ms);
 798
 799         /*
 800          * If we successfully made the connection, load the host private key
 801          * in case we will need it later for combined rsa-rhosts
 802          * authentication. This must be done before releasing extra
 803          * privileges, because the file is only readable by root.
 804          * If we cannot access the private keys, load the public keys
 805          * instead and try to execute the ssh-keysign helper instead.
 806          */
 807         sensitive_data.nkeys = 0;
 808         sensitive_data.keys = NULL;
 809         sensitive_data.external_keysign = 0;
 810         if (options.rhosts_rsa_authentication ||
 811             options.hostbased_authentication) {
 812                 sensitive_data.nkeys = 7;
 813                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 814                     sizeof(Key));
 815                 for (i = 0; i < sensitive_data.nkeys; i++)
 816                         sensitive_data.keys[i] = NULL;
 817
 818                 PRIV_START;
 819                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 820                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 821                 sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
 822                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 823 #ifdef OPENSSL_HAS_ECC
 824                 sensitive_data.keys[2] = key_load_private_cert(KEY_ECDSA,
 825                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
 826 #endif
 827                 sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
 828                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 829                 sensitive_data.keys[4] = key_load_private_type(KEY_DSA,
 830                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 831 #ifdef OPENSSL_HAS_ECC
 832                 sensitive_data.keys[5] = key_load_private_type(KEY_ECDSA,
 833                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
 834 #endif
 835                 sensitive_data.keys[6] = key_load_private_type(KEY_RSA,
 836                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 837                 PRIV_END;
 838
 839                 if (options.hostbased_authentication == 1 &&
 840                     sensitive_data.keys[0] == NULL &&
 841                     sensitive_data.keys[4] == NULL &&
 842                     sensitive_data.keys[5] == NULL &&
 843                     sensitive_data.keys[6] == NULL) {
 844                         sensitive_data.keys[1] = key_load_cert(
 845                             _PATH_HOST_DSA_KEY_FILE);
 846 #ifdef OPENSSL_HAS_ECC
 847                         sensitive_data.keys[2] = key_load_cert(
 848                             _PATH_HOST_ECDSA_KEY_FILE);
 849 #endif
 850                         sensitive_data.keys[3] = key_load_cert(
 851                             _PATH_HOST_RSA_KEY_FILE);
 852                         sensitive_data.keys[4] = key_load_public(
 853                             _PATH_HOST_DSA_KEY_FILE, NULL);
 854 #ifdef OPENSSL_HAS_ECC
 855                         sensitive_data.keys[5] = key_load_public(
 856                             _PATH_HOST_ECDSA_KEY_FILE, NULL);
 857 #endif
 858                         sensitive_data.keys[6] = key_load_public(
 859                             _PATH_HOST_RSA_KEY_FILE, NULL);
 860                         sensitive_data.external_keysign = 1;
 861                 }
 862         }
 863         /*
 864          * Get rid of any extra privileges that we may have.  We will no
 865          * longer need them.  Also, extra privileges could make it very hard
 866          * to read identity files and other non-world-readable files from the
 867          * user's home directory if it happens to be on a NFS volume where
 868          * root is mapped to nobody.
 869          */
 870         if (original_effective_uid == 0) {
 871                 PRIV_START;
 872                 permanently_set_uid(pw);
 873         }
 874
 875         /*
 876          * Now that we are back to our own permissions, create ~/.ssh
 877          * directory if it doesn't already exist.
 878          */
 879         r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
 880             strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 881         if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
 882 #ifdef WITH_SELINUX
 883                 ssh_selinux_setfscreatecon(buf);
 884 #endif
 885                 if (mkdir(buf, 0700) < 0)
 886                         error("Could not create directory '%.200s'.", buf);
 887 #ifdef WITH_SELINUX
 888                 ssh_selinux_setfscreatecon(NULL);
 889 #endif
 890         }
 891         /* load options.identity_files */
 892         load_public_identity_files();
 893
 894         /* Expand ~ in known host file names. */
 895         /* XXX mem-leaks: */
 896         options.system_hostfile =
 897             tilde_expand_filename(options.system_hostfile, original_real_uid);
 898         options.user_hostfile =
 899             tilde_expand_filename(options.user_hostfile, original_real_uid);
 900         options.system_hostfile2 =
 901             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 902         options.user_hostfile2 =
 903             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 904
 905         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 906         signal(SIGCHLD, main_sigchld_handler);
 907
 908         /* Log into the remote system.  Never returns if the login fails. */
 909         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 910             options.port, pw, timeout_ms);
 911
 912         if (packet_connection_is_on_socket()) {
 913                 verbose("Authenticated to %s ([%s]:%d).", host,
 914                     get_remote_ipaddr(), get_remote_port());
 915         } else {
 916                 verbose("Authenticated to %s (via proxy).", host);
 917         }
 918
 919         /* We no longer need the private host keys.  Clear them now. */
 920         if (sensitive_data.nkeys != 0) {
 921                 for (i = 0; i < sensitive_data.nkeys; i++) {
 922                         if (sensitive_data.keys[i] != NULL) {
 923                                 /* Destroys contents safely */
 924                                 debug3("clear hostkey %d", i);
 925                                 key_free(sensitive_data.keys[i]);
 926                                 sensitive_data.keys[i] = NULL;
 927                         }
 928                 }
 929                 xfree(sensitive_data.keys);
 930         }
 931         for (i = 0; i < options.num_identity_files; i++) {
 932                 if (options.identity_files[i]) {
 933                         xfree(options.identity_files[i]);
 934                         options.identity_files[i] = NULL;
 935                 }
 936                 if (options.identity_keys[i]) {
 937                         key_free(options.identity_keys[i]);
 938                         options.identity_keys[i] = NULL;
 939                 }
 940         }
 941
 942         exit_status = compat20 ? ssh_session2() : ssh_session();
 943         packet_close();
 944
 945         if (options.control_path != NULL && muxserver_sock != -1)
 946                 unlink(options.control_path);
 947
 948         /* Kill ProxyCommand if it is running. */
 949         ssh_kill_proxy_command();
 950
 951         return exit_status;
 952 }
 953
 954 static void
 955 control_persist_detach(void)
 956 {
 957         pid_t pid;
 958         int devnull;
 959
 960         debug("%s: backgrounding master process", __func__);
 961
 962         /*
 963          * master (current process) into the background, and make the
 964          * foreground process a client of the backgrounded master.
 965          */
 966         switch ((pid = fork())) {
 967         case -1:
 968                 fatal("%s: fork: %s", __func__, strerror(errno));
 969         case 0:
 970                 /* Child: master process continues mainloop */
 971                 break;
 972         default:
 973                 /* Parent: set up mux slave to connect to backgrounded master */
 974                 debug2("%s: background process is %ld", __func__, (long)pid);
 975                 stdin_null_flag = ostdin_null_flag;
 976                 no_shell_flag = ono_shell_flag;
 977                 no_tty_flag = ono_tty_flag;
 978                 tty_flag = otty_flag;
 979                 close(muxserver_sock);
 980                 muxserver_sock = -1;
 981                 options.control_master = SSHCTL_MASTER_NO;
 982                 muxclient(options.control_path);
 983                 /* muxclient() doesn't return on success. */
 984                 fatal("Failed to connect to new control master");
 985         }
 986         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
 987                 error("%s: open(\"/dev/null\"): %s", __func__,
 988                     strerror(errno));
 989         } else {
 990                 if (dup2(devnull, STDIN_FILENO) == -1 ||
 991                     dup2(devnull, STDOUT_FILENO) == -1)
 992                         error("%s: dup2: %s", __func__, strerror(errno));
 993                 if (devnull > STDERR_FILENO)
 994                         close(devnull);
 995         }
 996 }
 997
 998 /* Do fork() after authentication. Used by "ssh -f" */
 999 static void
1000 fork_postauth(void)
1001 {
1002         if (need_controlpersist_detach)
1003                 control_persist_detach();
1004         debug("forking to background");
1005         fork_after_authentication_flag = 0;
1006         if (daemon(1, 1) < 0)
1007                 fatal("daemon() failed: %.200s", strerror(errno));
1008 }
1009
1010 /* Callback for remote forward global requests */
1011 static void
1012 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
1013 {
1014         Forward *rfwd = (Forward *)ctxt;
1015
1016         /* XXX verbose() on failure? */
1017         debug("remote forward %s for: listen %d, connect %s:%d",
1018             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1019             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
1020         if (type == SSH2_MSG_REQUEST_SUCCESS && rfwd->listen_port == 0) {
1021                 rfwd->allocated_port = packet_get_int();
1022                 logit("Allocated port %u for remote forward to %s:%d",
1023                     rfwd->allocated_port,
1024                     rfwd->connect_host, rfwd->connect_port);
1025         }
1026
1027         if (type == SSH2_MSG_REQUEST_FAILURE) {
1028                 if (options.exit_on_forward_failure)
1029                         fatal("Error: remote port forwarding failed for "
1030                             "listen port %d", rfwd->listen_port);
1031                 else
1032                         logit("Warning: remote port forwarding failed for "
1033                             "listen port %d", rfwd->listen_port);
1034         }
1035         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1036                 debug("All remote forwarding requests processed");
1037                 if (fork_after_authentication_flag)
1038                         fork_postauth();
1039         }
1040 }
1041
1042 static void
1043 client_cleanup_stdio_fwd(int id, void *arg)
1044 {
1045         debug("stdio forwarding: done");
1046         cleanup_exit(0);
1047 }
1048
1049 static int
1050 client_setup_stdio_fwd(const char *host_to_connect, u_short port_to_connect)
1051 {
1052         Channel *c;
1053         int in, out;
1054
1055         debug3("client_setup_stdio_fwd %s:%d", host_to_connect,
1056             port_to_connect);
1057
1058         in = dup(STDIN_FILENO);
1059         out = dup(STDOUT_FILENO);
1060         if (in < 0 || out < 0)
1061                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1062
1063         if ((c = channel_connect_stdio_fwd(host_to_connect, port_to_connect,
1064             in, out)) == NULL)
1065                 return 0;
1066         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1067         return 1;
1068 }
1069
1070 static void
1071 ssh_init_forwarding(void)
1072 {
1073         int success = 0;
1074         int i;
1075
1076         if (stdio_forward_host != NULL) {
1077                 if (!compat20) {
1078                         fatal("stdio forwarding require Protocol 2");
1079                 }
1080                 if (!client_setup_stdio_fwd(stdio_forward_host,
1081                     stdio_forward_port))
1082                         fatal("Failed to connect in stdio forward mode.");
1083         }
1084
1085         /* Initiate local TCP/IP port forwardings. */
1086         for (i = 0; i < options.num_local_forwards; i++) {
1087                 debug("Local connections to %.200s:%d forwarded to remote "
1088                     "address %.200s:%d",
1089                     (options.local_forwards[i].listen_host == NULL) ?
1090                     (options.gateway_ports ? "*" : "LOCALHOST") :
1091                     options.local_forwards[i].listen_host,
1092                     options.local_forwards[i].listen_port,
1093                     options.local_forwards[i].connect_host,
1094                     options.local_forwards[i].connect_port);
1095                 success += channel_setup_local_fwd_listener(
1096                     options.local_forwards[i].listen_host,
1097                     options.local_forwards[i].listen_port,
1098                     options.local_forwards[i].connect_host,
1099                     options.local_forwards[i].connect_port,
1100                     options.gateway_ports);
1101         }
1102         if (i > 0 && success != i && options.exit_on_forward_failure)
1103                 fatal("Could not request local forwarding.");
1104         if (i > 0 && success == 0)
1105                 error("Could not request local forwarding.");
1106
1107         /* Initiate remote TCP/IP port forwardings. */
1108         for (i = 0; i < options.num_remote_forwards; i++) {
1109                 debug("Remote connections from %.200s:%d forwarded to "
1110                     "local address %.200s:%d",
1111                     (options.remote_forwards[i].listen_host == NULL) ?
1112                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1113                     options.remote_forwards[i].listen_port,
1114                     options.remote_forwards[i].connect_host,
1115                     options.remote_forwards[i].connect_port);
1116                 if (channel_request_remote_forwarding(
1117                     options.remote_forwards[i].listen_host,
1118                     options.remote_forwards[i].listen_port,
1119                     options.remote_forwards[i].connect_host,
1120                     options.remote_forwards[i].connect_port) < 0) {
1121                         if (options.exit_on_forward_failure)
1122                                 fatal("Could not request remote forwarding.");
1123                         else
1124                                 logit("Warning: Could not request remote "
1125                                     "forwarding.");
1126                 }
1127                 client_register_global_confirm(ssh_confirm_remote_forward,
1128                     &options.remote_forwards[i]);
1129         }
1130
1131         /* Initiate tunnel forwarding. */
1132         if (options.tun_open != SSH_TUNMODE_NO) {
1133                 if (client_request_tun_fwd(options.tun_open,
1134                     options.tun_local, options.tun_remote) == -1) {
1135                         if (options.exit_on_forward_failure)
1136                                 fatal("Could not request tunnel forwarding.");
1137                         else
1138                                 error("Could not request tunnel forwarding.");
1139                 }
1140         }
1141 }
1142
1143 static void
1144 check_agent_present(void)
1145 {
1146         if (options.forward_agent) {
1147                 /* Clear agent forwarding if we don't have an agent. */
1148                 if (!ssh_agent_present())
1149                         options.forward_agent = 0;
1150         }
1151 }
1152
1153 static int
1154 ssh_session(void)
1155 {
1156         int type;
1157         int interactive = 0;
1158         int have_tty = 0;
1159         struct winsize ws;
1160         char *cp;
1161         const char *display;
1162
1163         /* Enable compression if requested. */
1164         if (options.compression) {
1165                 debug("Requesting compression at level %d.",
1166                     options.compression_level);
1167
1168                 if (options.compression_level < 1 ||
1169                     options.compression_level > 9)
1170                         fatal("Compression level must be from 1 (fast) to "
1171                             "9 (slow, best).");
1172
1173                 /* Send the request. */
1174                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1175                 packet_put_int(options.compression_level);
1176                 packet_send();
1177                 packet_write_wait();
1178                 type = packet_read();
1179                 if (type == SSH_SMSG_SUCCESS)
1180                         packet_start_compression(options.compression_level);
1181                 else if (type == SSH_SMSG_FAILURE)
1182                         logit("Warning: Remote host refused compression.");
1183                 else
1184                         packet_disconnect("Protocol error waiting for "
1185                             "compression response.");
1186         }
1187         /* Allocate a pseudo tty if appropriate. */
1188         if (tty_flag) {
1189                 debug("Requesting pty.");
1190
1191                 /* Start the packet. */
1192                 packet_start(SSH_CMSG_REQUEST_PTY);
1193
1194                 /* Store TERM in the packet.  There is no limit on the
1195                    length of the string. */
1196                 cp = getenv("TERM");
1197                 if (!cp)
1198                         cp = "";
1199                 packet_put_cstring(cp);
1200
1201                 /* Store window size in the packet. */
1202                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1203                         memset(&ws, 0, sizeof(ws));
1204                 packet_put_int((u_int)ws.ws_row);
1205                 packet_put_int((u_int)ws.ws_col);
1206                 packet_put_int((u_int)ws.ws_xpixel);
1207                 packet_put_int((u_int)ws.ws_ypixel);
1208
1209                 /* Store tty modes in the packet. */
1210                 tty_make_modes(fileno(stdin), NULL);
1211
1212                 /* Send the packet, and wait for it to leave. */
1213                 packet_send();
1214                 packet_write_wait();
1215
1216                 /* Read response from the server. */
1217                 type = packet_read();
1218                 if (type == SSH_SMSG_SUCCESS) {
1219                         interactive = 1;
1220                         have_tty = 1;
1221                 } else if (type == SSH_SMSG_FAILURE)
1222                         logit("Warning: Remote host failed or refused to "
1223                             "allocate a pseudo tty.");
1224                 else
1225                         packet_disconnect("Protocol error waiting for pty "
1226                             "request response.");
1227         }
1228         /* Request X11 forwarding if enabled and DISPLAY is set. */
1229         display = getenv("DISPLAY");
1230         if (options.forward_x11 && display != NULL) {
1231                 char *proto, *data;
1232                 /* Get reasonable local authentication information. */
1233                 client_x11_get_proto(display, options.xauth_location,
1234                     options.forward_x11_trusted,
1235                     options.forward_x11_timeout,
1236                     &proto, &data);
1237                 /* Request forwarding with authentication spoofing. */
1238                 debug("Requesting X11 forwarding with authentication "
1239                     "spoofing.");
1240                 x11_request_forwarding_with_spoofing(0, display, proto, data);
1241
1242                 /* Read response from the server. */
1243                 type = packet_read();
1244                 if (type == SSH_SMSG_SUCCESS) {
1245                         interactive = 1;
1246                 } else if (type == SSH_SMSG_FAILURE) {
1247                         logit("Warning: Remote host denied X11 forwarding.");
1248                 } else {
1249                         packet_disconnect("Protocol error waiting for X11 "
1250                             "forwarding");
1251                 }
1252         }
1253         /* Tell the packet module whether this is an interactive session. */
1254         packet_set_interactive(interactive,
1255             options.ip_qos_interactive, options.ip_qos_bulk);
1256
1257         /* Request authentication agent forwarding if appropriate. */
1258         check_agent_present();
1259
1260         if (options.forward_agent) {
1261                 debug("Requesting authentication agent forwarding.");
1262                 auth_request_forwarding();
1263
1264                 /* Read response from the server. */
1265                 type = packet_read();
1266                 packet_check_eom();
1267                 if (type != SSH_SMSG_SUCCESS)
1268                         logit("Warning: Remote host denied authentication agent forwarding.");
1269         }
1270
1271         /* Initiate port forwardings. */
1272         ssh_init_forwarding();
1273
1274         /* Execute a local command */
1275         if (options.local_command != NULL &&
1276             options.permit_local_command)
1277                 ssh_local_cmd(options.local_command);
1278
1279         /*
1280          * If requested and we are not interested in replies to remote
1281          * forwarding requests, then let ssh continue in the background.
1282          */
1283         if (fork_after_authentication_flag) {
1284                 if (options.exit_on_forward_failure &&
1285                     options.num_remote_forwards > 0) {
1286                         debug("deferring postauth fork until remote forward "
1287                             "confirmation received");
1288                 } else
1289                         fork_postauth();
1290         }
1291
1292         /*
1293          * If a command was specified on the command line, execute the
1294          * command now. Otherwise request the server to start a shell.
1295          */
1296         if (buffer_len(&command) > 0) {
1297                 int len = buffer_len(&command);
1298                 if (len > 900)
1299                         len = 900;
1300                 debug("Sending command: %.*s", len,
1301                     (u_char *)buffer_ptr(&command));
1302                 packet_start(SSH_CMSG_EXEC_CMD);
1303                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1304                 packet_send();
1305                 packet_write_wait();
1306         } else {
1307                 debug("Requesting shell.");
1308                 packet_start(SSH_CMSG_EXEC_SHELL);
1309                 packet_send();
1310                 packet_write_wait();
1311         }
1312
1313         /* Enter the interactive session. */
1314         return client_loop(have_tty, tty_flag ?
1315             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1316 }
1317
1318 /* request pty/x11/agent/tcpfwd/shell for channel */
1319 static void
1320 ssh_session2_setup(int id, int success, void *arg)
1321 {
1322         extern char **environ;
1323         const char *display;
1324         int interactive = tty_flag;
1325
1326         if (!success)
1327                 return; /* No need for error message, channels code sens one */
1328
1329         display = getenv("DISPLAY");
1330         if (options.forward_x11 && display != NULL) {
1331                 char *proto, *data;
1332                 /* Get reasonable local authentication information. */
1333                 client_x11_get_proto(display, options.xauth_location,
1334                     options.forward_x11_trusted,
1335                     options.forward_x11_timeout, &proto, &data);
1336                 /* Request forwarding with authentication spoofing. */
1337                 debug("Requesting X11 forwarding with authentication "
1338                     "spoofing.");
1339                 x11_request_forwarding_with_spoofing(id, display, proto, data);
1340                 interactive = 1;
1341                 /* XXX wait for reply */
1342         }
1343
1344         check_agent_present();
1345         if (options.forward_agent) {
1346                 debug("Requesting authentication agent forwarding.");
1347                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1348                 packet_send();
1349         }
1350
1351         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1352             NULL, fileno(stdin), &command, environ);
1353 }
1354
1355 /* open new channel for a session */
1356 static int
1357 ssh_session2_open(void)
1358 {
1359         Channel *c;
1360         int window, packetmax, in, out, err;
1361
1362         if (stdin_null_flag) {
1363                 in = open(_PATH_DEVNULL, O_RDONLY);
1364         } else {
1365                 in = dup(STDIN_FILENO);
1366         }
1367         out = dup(STDOUT_FILENO);
1368         err = dup(STDERR_FILENO);
1369
1370         if (in < 0 || out < 0 || err < 0)
1371                 fatal("dup() in/out/err failed");
1372
1373         /* enable nonblocking unless tty */
1374         if (!isatty(in))
1375                 set_nonblock(in);
1376         if (!isatty(out))
1377                 set_nonblock(out);
1378         if (!isatty(err))
1379                 set_nonblock(err);
1380
1381         /*
1382          * We need to check to see what to do about buffer sizes here.
1383          * - In an HPN to non-HPN connection we want to limit the window size to
1384          *   something reasonable in case the far side has the large window bug.
1385          * - In an HPN to HPN connection we want to use the max window size but
1386          *   allow the user to override it.
1387          * - Lastly if HPN is disabled then use the ssh standard window size.
1388          *
1389          * We cannot just do a getsockopt() here and set the ssh window to that
1390          * as in case of autotuning of socket buffers the window would get stuck
1391          * at the initial buffer size, generally less than 96k.  Therefore we
1392          * need to set the maximum ssh window size to the maximum HPN buffer
1393          * size unless the user has set TcpRcvBufPoll to no.  In that case we
1394          * can just set the window to the minimum of HPN buffer size and TCP
1395          * receive buffer size.
1396          */
1397         if (tty_flag)
1398                 options.hpn_buffer_size = CHAN_SES_WINDOW_DEFAULT;
1399         else
1400                 options.hpn_buffer_size = CHAN_HPN_MIN_WINDOW_DEFAULT;
1401
1402         if (datafellows & SSH_BUG_LARGEWINDOW) {
1403                 debug("HPN to Non-HPN Connection");
1404         } else if (options.tcp_rcv_buf_poll <= 0) {
1405                 sock_get_rcvbuf(&options.hpn_buffer_size, 0);
1406                 debug("HPNBufferSize set to TCP RWIN: %d",
1407                     options.hpn_buffer_size);
1408         } else if (options.tcp_rcv_buf > 0) {
1409                 sock_get_rcvbuf(&options.hpn_buffer_size,
1410                     options.tcp_rcv_buf);
1411                 debug("HPNBufferSize set to user TCPRcvBuf: %d",
1412                     options.hpn_buffer_size);
1413         }
1414         debug("Final hpn_buffer_size = %d", options.hpn_buffer_size);
1415         channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1416         window = options.hpn_buffer_size;
1417
1418         packetmax = CHAN_SES_PACKET_DEFAULT;
1419         if (tty_flag) {
1420                 window = CHAN_SES_WINDOW_DEFAULT;
1421                 window >>= 1;
1422                 packetmax >>= 1;
1423         }
1424         c = channel_new(
1425             "session", SSH_CHANNEL_OPENING, in, out, err,
1426             window, packetmax, CHAN_EXTENDED_WRITE,
1427             "client-session", /*nonblock*/0);
1428         if (!options.hpn_disabled && options.tcp_rcv_buf_poll > 0) {
1429                 c->dynamic_window = 1;
1430                 debug("Enabled Dynamic Window Scaling\n");
1431         }
1432         debug3("ssh_session2_open: channel_new: %d", c->self);
1433
1434         channel_send_open(c->self);
1435         if (!no_shell_flag)
1436                 channel_register_open_confirm(c->self,
1437                     ssh_session2_setup, NULL);
1438
1439         return c->self;
1440 }
1441
1442 static int
1443 ssh_session2(void)
1444 {
1445         int id = -1;
1446
1447         /* XXX should be pre-session */
1448         ssh_init_forwarding();
1449
1450         /* Start listening for multiplex clients */
1451         muxserver_listen();
1452
1453         /*
1454          * If we are in control persist mode, then prepare to background
1455          * ourselves and have a foreground client attach as a control
1456          * slave. NB. we must save copies of the flags that we override for
1457          * the backgrounding, since we defer attachment of the slave until
1458          * after the connection is fully established (in particular,
1459          * async rfwd replies have been received for ExitOnForwardFailure).
1460          */
1461         if (options.control_persist && muxserver_sock != -1) {
1462                 ostdin_null_flag = stdin_null_flag;
1463                 ono_shell_flag = no_shell_flag;
1464                 ono_tty_flag = no_tty_flag;
1465                 otty_flag = tty_flag;
1466                 stdin_null_flag = 1;
1467                 no_shell_flag = 1;
1468                 no_tty_flag = 1;
1469                 tty_flag = 0;
1470                 if (!fork_after_authentication_flag)
1471                         need_controlpersist_detach = 1;
1472                 fork_after_authentication_flag = 1;
1473         }
1474
1475         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1476                 id = ssh_session2_open();
1477
1478         /* If we don't expect to open a new session, then disallow it */
1479         if (options.control_master == SSHCTL_MASTER_NO &&
1480             (datafellows & SSH_NEW_OPENSSH)) {
1481                 debug("Requesting no-more-sessions@openssh.com");
1482                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1483                 packet_put_cstring("no-more-sessions@openssh.com");
1484                 packet_put_char(0);
1485                 packet_send();
1486         }
1487
1488         /* Execute a local command */
1489         if (options.local_command != NULL &&
1490             options.permit_local_command)
1491                 ssh_local_cmd(options.local_command);
1492
1493         /*
1494          * If requested and we are not interested in replies to remote
1495          * forwarding requests, then let ssh continue in the background.
1496          */
1497         if (fork_after_authentication_flag) {
1498                 if (options.exit_on_forward_failure &&
1499                     options.num_remote_forwards > 0) {
1500                         debug("deferring postauth fork until remote forward "
1501                             "confirmation received");
1502                 } else
1503                         fork_postauth();
1504         }
1505
1506         if (options.use_roaming)
1507                 request_roaming();
1508
1509         return client_loop(tty_flag, tty_flag ?
1510             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1511 }
1512
1513 static void
1514 load_public_identity_files(void)
1515 {
1516         char *filename, *cp, thishost[NI_MAXHOST];
1517         char *pwdir = NULL, *pwname = NULL;
1518         int i = 0;
1519         Key *public;
1520         struct passwd *pw;
1521         u_int n_ids;
1522         char *identity_files[SSH_MAX_IDENTITY_FILES];
1523         Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1524 #ifdef ENABLE_PKCS11
1525         Key **keys;
1526         int nkeys;
1527 #endif /* PKCS11 */
1528
1529         n_ids = 0;
1530         bzero(identity_files, sizeof(identity_files));
1531         bzero(identity_keys, sizeof(identity_keys));
1532
1533 #ifdef ENABLE_PKCS11
1534         if (options.pkcs11_provider != NULL &&
1535             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1536             (pkcs11_init(!options.batch_mode) == 0) &&
1537             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1538             &keys)) > 0) {
1539                 for (i = 0; i < nkeys; i++) {
1540                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1541                                 key_free(keys[i]);
1542                                 continue;
1543                         }
1544                         identity_keys[n_ids] = keys[i];
1545                         identity_files[n_ids] =
1546                             xstrdup(options.pkcs11_provider); /* XXX */
1547                         n_ids++;
1548                 }
1549                 xfree(keys);
1550         }
1551 #endif /* ENABLE_PKCS11 */
1552         if ((pw = getpwuid(original_real_uid)) == NULL)
1553                 fatal("load_public_identity_files: getpwuid failed");
1554         pwname = xstrdup(pw->pw_name);
1555         pwdir = xstrdup(pw->pw_dir);
1556         if (gethostname(thishost, sizeof(thishost)) == -1)
1557                 fatal("load_public_identity_files: gethostname: %s",
1558                     strerror(errno));
1559         for (i = 0; i < options.num_identity_files; i++) {
1560                 if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1561                         xfree(options.identity_files[i]);
1562                         continue;
1563                 }
1564                 cp = tilde_expand_filename(options.identity_files[i],
1565                     original_real_uid);
1566                 filename = percent_expand(cp, "d", pwdir,
1567                     "u", pwname, "l", thishost, "h", host,
1568                     "r", options.user, (char *)NULL);
1569                 xfree(cp);
1570                 public = key_load_public(filename, NULL);
1571                 debug("identity file %s type %d", filename,
1572                     public ? public->type : -1);
1573                 xfree(options.identity_files[i]);
1574                 identity_files[n_ids] = filename;
1575                 identity_keys[n_ids] = public;
1576
1577                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
1578                         continue;
1579
1580                 /* Try to add the certificate variant too */
1581                 xasprintf(&cp, "%s-cert", filename);
1582                 public = key_load_public(cp, NULL);
1583                 debug("identity file %s type %d", cp,
1584                     public ? public->type : -1);
1585                 if (public == NULL) {
1586                         xfree(cp);
1587                         continue;
1588                 }
1589                 if (!key_is_cert(public)) {
1590                         debug("%s: key %s type %s is not a certificate",
1591                             __func__, cp, key_type(public));
1592                         key_free(public);
1593                         xfree(cp);
1594                         continue;
1595                 }
1596                 identity_keys[n_ids] = public;
1597                 /* point to the original path, most likely the private key */
1598                 identity_files[n_ids] = xstrdup(filename);
1599                 n_ids++;
1600         }
1601         options.num_identity_files = n_ids;
1602         memcpy(options.identity_files, identity_files, sizeof(identity_files));
1603         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
1604
1605         bzero(pwname, strlen(pwname));
1606         xfree(pwname);
1607         bzero(pwdir, strlen(pwdir));
1608         xfree(pwdir);
1609 }
1610
1611 static void
1612 main_sigchld_handler(int sig)
1613 {
1614         int save_errno = errno;
1615         pid_t pid;
1616         int status;
1617
1618         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
1619             (pid < 0 && errno == EINTR))
1620                 ;
1621
1622         signal(sig, main_sigchld_handler);
1623         errno = save_errno;
1624 }
1625