crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.381 2013/07/25 00:29:10 djm Exp $ */
   2 /* $FreeBSD$ */
   3 /*
   4  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   5  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   6  *                    All rights reserved
   7  * Ssh client program.  This program can be used to log into a remote machine.
   8  * The software supports strong authentication, encryption, and forwarding
   9  * of X11, TCP/IP, and authentication connections.
  10  *
  11  * As far as I am concerned, the code I have written for this software
  12  * can be used freely for any purpose.  Any derived versions of this
  13  * software must be clearly marked as such, and if the derived work is
  14  * incompatible with the protocol description in the RFC file, it must be
  15  * called by a name other than "ssh" or "Secure Shell".
  16  *
  17  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  18  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  19  *
  20  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  21  * in Canada (German citizen).
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the above copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  *
  32  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  33  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  34  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  35  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  36  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  37  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  38  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  39  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  40  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  41  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  42  */
  43
  44 #include "includes.h"
  45 __RCSID("$FreeBSD$");
  46
  47 #include <sys/types.h>
  48 #ifdef HAVE_SYS_STAT_H
  49 # include <sys/stat.h>
  50 #endif
  51 #include <sys/resource.h>
  52 #include <sys/ioctl.h>
  53 #include <sys/param.h>
  54 #include <sys/socket.h>
  55 #include <sys/wait.h>
  56
  57 #include <ctype.h>
  58 #include <errno.h>
  59 #include <fcntl.h>
  60 #include <netdb.h>
  61 #ifdef HAVE_PATHS_H
  62 #include <paths.h>
  63 #endif
  64 #include <pwd.h>
  65 #include <signal.h>
  66 #include <stdarg.h>
  67 #include <stddef.h>
  68 #include <stdio.h>
  69 #include <stdlib.h>
  70 #include <string.h>
  71 #include <unistd.h>
  72
  73 #include <netinet/in.h>
  74 #include <arpa/inet.h>
  75
  76 #include <openssl/evp.h>
  77 #include <openssl/err.h>
  78 #include "openbsd-compat/openssl-compat.h"
  79 #include "openbsd-compat/sys-queue.h"
  80
  81 #include "xmalloc.h"
  82 #include "ssh.h"
  83 #include "ssh1.h"
  84 #include "ssh2.h"
  85 #include "canohost.h"
  86 #include "compat.h"
  87 #include "cipher.h"
  88 #include "packet.h"
  89 #include "buffer.h"
  90 #include "channels.h"
  91 #include "key.h"
  92 #include "authfd.h"
  93 #include "authfile.h"
  94 #include "pathnames.h"
  95 #include "dispatch.h"
  96 #include "clientloop.h"
  97 #include "log.h"
  98 #include "readconf.h"
  99 #include "sshconnect.h"
 100 #include "misc.h"
 101 #include "kex.h"
 102 #include "mac.h"
 103 #include "sshpty.h"
 104 #include "match.h"
 105 #include "msg.h"
 106 #include "uidswap.h"
 107 #include "roaming.h"
 108 #include "version.h"
 109
 110 #ifdef ENABLE_PKCS11
 111 #include "ssh-pkcs11.h"
 112 #endif
 113
 114 extern char *__progname;
 115
 116 /* Saves a copy of argv for setproctitle emulation */
 117 #ifndef HAVE_SETPROCTITLE
 118 static char **saved_av;
 119 #endif
 120
 121 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 122 int debug_flag = 0;
 123
 124 /* Flag indicating whether a tty should be requested */
 125 int tty_flag = 0;
 126
 127 /* don't exec a shell */
 128 int no_shell_flag = 0;
 129
 130 /*
 131  * Flag indicating that nothing should be read from stdin.  This can be set
 132  * on the command line.
 133  */
 134 int stdin_null_flag = 0;
 135
 136 /*
 137  * Flag indicating that the current process should be backgrounded and
 138  * a new slave launched in the foreground for ControlPersist.
 139  */
 140 int need_controlpersist_detach = 0;
 141
 142 /* Copies of flags for ControlPersist foreground slave */
 143 int ostdin_null_flag, ono_shell_flag, otty_flag, orequest_tty;
 144
 145 /*
 146  * Flag indicating that ssh should fork after authentication.  This is useful
 147  * so that the passphrase can be entered manually, and then ssh goes to the
 148  * background.
 149  */
 150 int fork_after_authentication_flag = 0;
 151
 152 /* forward stdio to remote host and port */
 153 char *stdio_forward_host = NULL;
 154 int stdio_forward_port = 0;
 155
 156 /*
 157  * General data structure for command line options and options configurable
 158  * in configuration files.  See readconf.h.
 159  */
 160 Options options;
 161
 162 /* optional user configfile */
 163 char *config = NULL;
 164
 165 /*
 166  * Name of the host we are connecting to.  This is the name given on the
 167  * command line, or the HostName specified for the user-supplied name in a
 168  * configuration file.
 169  */
 170 char *host;
 171
 172 /* socket address the host resolves to */
 173 struct sockaddr_storage hostaddr;
 174
 175 /* Private host keys. */
 176 Sensitive sensitive_data;
 177
 178 /* Original real UID. */
 179 uid_t original_real_uid;
 180 uid_t original_effective_uid;
 181
 182 /* command to be executed */
 183 Buffer command;
 184
 185 /* Should we execute a command or invoke a subsystem? */
 186 int subsystem_flag = 0;
 187
 188 /* # of replies received for global requests */
 189 static int remote_forward_confirms_received = 0;
 190
 191 /* mux.c */
 192 extern int muxserver_sock;
 193 extern u_int muxclient_command;
 194
 195 /* Prints a help message to the user.  This function never returns. */
 196
 197 static void
 198 usage(void)
 199 {
 200         fprintf(stderr,
 201 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
 202 "           [-D [bind_address:]port] [-E log_file] [-e escape_char]\n"
 203 "           [-F configfile] [-I pkcs11] [-i identity_file]\n"
 204 "           [-L [bind_address:]port:host:hostport] [-Q protocol_feature]\n"
 205 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 206 "           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
 207 "           [-W host:port] [-w local_tun[:remote_tun]]\n"
 208 "           [user@]hostname [command]\n"
 209         );
 210         exit(255);
 211 }
 212
 213 static int ssh_session(void);
 214 static int ssh_session2(void);
 215 static void load_public_identity_files(void);
 216 static void main_sigchld_handler(int);
 217
 218 /* from muxclient.c */
 219 void muxclient(const char *);
 220 void muxserver_listen(void);
 221
 222 /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
 223 static void
 224 tilde_expand_paths(char **paths, u_int num_paths)
 225 {
 226         u_int i;
 227         char *cp;
 228
 229         for (i = 0; i < num_paths; i++) {
 230                 cp = tilde_expand_filename(paths[i], original_real_uid);
 231                 free(paths[i]);
 232                 paths[i] = cp;
 233         }
 234 }
 235
 236 /*
 237  * Main program for the ssh client.
 238  */
 239 int
 240 main(int ac, char **av)
 241 {
 242         int i, r, opt, exit_status, use_syslog;
 243         char *p, *cp, *line, *argv0, buf[MAXPATHLEN], *host_arg, *logfile;
 244         char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
 245         struct stat st;
 246         struct passwd *pw;
 247         int dummy, timeout_ms;
 248         extern int optind, optreset;
 249         extern char *optarg;
 250
 251         struct servent *sp;
 252         Forward fwd;
 253
 254         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 255         sanitise_stdfd();
 256
 257         __progname = ssh_get_progname(av[0]);
 258
 259 #ifndef HAVE_SETPROCTITLE
 260         /* Prepare for later setproctitle emulation */
 261         /* Save argv so it isn't clobbered by setproctitle() emulation */
 262         saved_av = xcalloc(ac + 1, sizeof(*saved_av));
 263         for (i = 0; i < ac; i++)
 264                 saved_av[i] = xstrdup(av[i]);
 265         saved_av[i] = NULL;
 266         compat_init_setproctitle(ac, av);
 267         av = saved_av;
 268 #endif
 269
 270         /*
 271          * Discard other fds that are hanging around. These can cause problem
 272          * with backgrounded ssh processes started by ControlPersist.
 273          */
 274         closefrom(STDERR_FILENO + 1);
 275
 276         /*
 277          * Save the original real uid.  It will be needed later (uid-swapping
 278          * may clobber the real uid).
 279          */
 280         original_real_uid = getuid();
 281         original_effective_uid = geteuid();
 282
 283         /*
 284          * Use uid-swapping to give up root privileges for the duration of
 285          * option processing.  We will re-instantiate the rights when we are
 286          * ready to create the privileged port, and will permanently drop
 287          * them when the port has been created (actually, when the connection
 288          * has been made, as we may need to create the port several times).
 289          */
 290         PRIV_END;
 291
 292 #ifdef HAVE_SETRLIMIT
 293         /* If we are installed setuid root be careful to not drop core. */
 294         if (original_real_uid != original_effective_uid) {
 295                 struct rlimit rlim;
 296                 rlim.rlim_cur = rlim.rlim_max = 0;
 297                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 298                         fatal("setrlimit failed: %.100s", strerror(errno));
 299         }
 300 #endif
 301         /* Get user data. */
 302         pw = getpwuid(original_real_uid);
 303         if (!pw) {
 304                 logit("No user exists for uid %lu", (u_long)original_real_uid);
 305                 exit(255);
 306         }
 307         /* Take a copy of the returned structure. */
 308         pw = pwcopy(pw);
 309
 310         /*
 311          * Set our umask to something reasonable, as some files are created
 312          * with the default umask.  This will make them world-readable but
 313          * writable only by the owner, which is ok for all files for which we
 314          * don't set the modes explicitly.
 315          */
 316         umask(022);
 317
 318         /*
 319          * Initialize option structure to indicate that no values have been
 320          * set.
 321          */
 322         initialize_options(&options);
 323
 324         /* Parse command-line arguments. */
 325         host = NULL;
 326         use_syslog = 0;
 327         logfile = NULL;
 328         argv0 = av[0];
 329
 330  again:
 331         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 332             "ACD:E:F:I:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) {
 333                 switch (opt) {
 334                 case '1':
 335                         options.protocol = SSH_PROTO_1;
 336                         break;
 337                 case '2':
 338                         options.protocol = SSH_PROTO_2;
 339                         break;
 340                 case '4':
 341                         options.address_family = AF_INET;
 342                         break;
 343                 case '6':
 344                         options.address_family = AF_INET6;
 345                         break;
 346                 case 'n':
 347                         stdin_null_flag = 1;
 348                         break;
 349                 case 'f':
 350                         fork_after_authentication_flag = 1;
 351                         stdin_null_flag = 1;
 352                         break;
 353                 case 'x':
 354                         options.forward_x11 = 0;
 355                         break;
 356                 case 'X':
 357                         options.forward_x11 = 1;
 358                         break;
 359                 case 'y':
 360                         use_syslog = 1;
 361                         break;
 362                 case 'E':
 363                         logfile = xstrdup(optarg);
 364                         break;
 365                 case 'Y':
 366                         options.forward_x11 = 1;
 367                         options.forward_x11_trusted = 1;
 368                         break;
 369                 case 'g':
 370                         options.gateway_ports = 1;
 371                         break;
 372                 case 'O':
 373                         if (stdio_forward_host != NULL)
 374                                 fatal("Cannot specify multiplexing "
 375                                     "command with -W");
 376                         else if (muxclient_command != 0)
 377                                 fatal("Multiplexing command already specified");
 378                         if (strcmp(optarg, "check") == 0)
 379                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 380                         else if (strcmp(optarg, "forward") == 0)
 381                                 muxclient_command = SSHMUX_COMMAND_FORWARD;
 382                         else if (strcmp(optarg, "exit") == 0)
 383                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 384                         else if (strcmp(optarg, "stop") == 0)
 385                                 muxclient_command = SSHMUX_COMMAND_STOP;
 386                         else if (strcmp(optarg, "cancel") == 0)
 387                                 muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
 388                         else
 389                                 fatal("Invalid multiplex command.");
 390                         break;
 391                 case 'P':       /* deprecated */
 392                         options.use_privileged_port = 0;
 393                         break;
 394                 case 'Q':       /* deprecated */
 395                         cp = NULL;
 396                         if (strcasecmp(optarg, "cipher") == 0)
 397                                 cp = cipher_alg_list();
 398                         else if (strcasecmp(optarg, "mac") == 0)
 399                                 cp = mac_alg_list();
 400                         else if (strcasecmp(optarg, "kex") == 0)
 401                                 cp = kex_alg_list();
 402                         else if (strcasecmp(optarg, "key") == 0)
 403                                 cp = key_alg_list();
 404                         if (cp == NULL)
 405                                 fatal("Unsupported query \"%s\"", optarg);
 406                         printf("%s\n", cp);
 407                         free(cp);
 408                         exit(0);
 409                         break;
 410                 case 'a':
 411                         options.forward_agent = 0;
 412                         break;
 413                 case 'A':
 414                         options.forward_agent = 1;
 415                         break;
 416                 case 'k':
 417                         options.gss_deleg_creds = 0;
 418                         break;
 419                 case 'K':
 420                         options.gss_authentication = 1;
 421                         options.gss_deleg_creds = 1;
 422                         break;
 423                 case 'i':
 424                         if (stat(optarg, &st) < 0) {
 425                                 fprintf(stderr, "Warning: Identity file %s "
 426                                     "not accessible: %s.\n", optarg,
 427                                     strerror(errno));
 428                                 break;
 429                         }
 430                         add_identity_file(&options, NULL, optarg, 1);
 431                         break;
 432                 case 'I':
 433 #ifdef ENABLE_PKCS11
 434                         options.pkcs11_provider = xstrdup(optarg);
 435 #else
 436                         fprintf(stderr, "no support for PKCS#11.\n");
 437 #endif
 438                         break;
 439                 case 't':
 440                         if (options.request_tty == REQUEST_TTY_YES)
 441                                 options.request_tty = REQUEST_TTY_FORCE;
 442                         else
 443                                 options.request_tty = REQUEST_TTY_YES;
 444                         break;
 445                 case 'v':
 446                         if (debug_flag == 0) {
 447                                 debug_flag = 1;
 448                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 449                         } else {
 450                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 451                                         options.log_level++;
 452                         }
 453                         break;
 454                 case 'V':
 455                         if (options.version_addendum &&
 456                             *options.version_addendum != '\0')
 457                                 fprintf(stderr, "%s%s %s, %s\n", SSH_RELEASE,
 458                                     options.hpn_disabled ? "" : SSH_VERSION_HPN,
 459                                     options.version_addendum,
 460                                     SSLeay_version(SSLEAY_VERSION));
 461                         else
 462                                 fprintf(stderr, "%s%s, %s\n", SSH_RELEASE,
 463                                     options.hpn_disabled ? "" : SSH_VERSION_HPN,
 464                                     SSLeay_version(SSLEAY_VERSION));
 465                         if (opt == 'V')
 466                                 exit(0);
 467                         break;
 468                 case 'w':
 469                         if (options.tun_open == -1)
 470                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 471                         options.tun_local = a2tun(optarg, &options.tun_remote);
 472                         if (options.tun_local == SSH_TUNID_ERR) {
 473                                 fprintf(stderr,
 474                                     "Bad tun device '%s'\n", optarg);
 475                                 exit(255);
 476                         }
 477                         break;
 478                 case 'W':
 479                         if (stdio_forward_host != NULL)
 480                                 fatal("stdio forward already specified");
 481                         if (muxclient_command != 0)
 482                                 fatal("Cannot specify stdio forward with -O");
 483                         if (parse_forward(&fwd, optarg, 1, 0)) {
 484                                 stdio_forward_host = fwd.listen_host;
 485                                 stdio_forward_port = fwd.listen_port;
 486                                 free(fwd.connect_host);
 487                         } else {
 488                                 fprintf(stderr,
 489                                     "Bad stdio forwarding specification '%s'\n",
 490                                     optarg);
 491                                 exit(255);
 492                         }
 493                         options.request_tty = REQUEST_TTY_NO;
 494                         no_shell_flag = 1;
 495                         options.clear_forwardings = 1;
 496                         options.exit_on_forward_failure = 1;
 497                         break;
 498                 case 'q':
 499                         options.log_level = SYSLOG_LEVEL_QUIET;
 500                         break;
 501                 case 'e':
 502                         if (optarg[0] == '^' && optarg[2] == 0 &&
 503                             (u_char) optarg[1] >= 64 &&
 504                             (u_char) optarg[1] < 128)
 505                                 options.escape_char = (u_char) optarg[1] & 31;
 506                         else if (strlen(optarg) == 1)
 507                                 options.escape_char = (u_char) optarg[0];
 508                         else if (strcmp(optarg, "none") == 0)
 509                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 510                         else {
 511                                 fprintf(stderr, "Bad escape character '%s'.\n",
 512                                     optarg);
 513                                 exit(255);
 514                         }
 515                         break;
 516                 case 'c':
 517                         if (ciphers_valid(optarg)) {
 518                                 /* SSH2 only */
 519                                 options.ciphers = xstrdup(optarg);
 520                                 options.cipher = SSH_CIPHER_INVALID;
 521                         } else {
 522                                 /* SSH1 only */
 523                                 options.cipher = cipher_number(optarg);
 524                                 if (options.cipher == -1) {
 525                                         fprintf(stderr,
 526                                             "Unknown cipher type '%s'\n",
 527                                             optarg);
 528                                         exit(255);
 529                                 }
 530                                 if (options.cipher == SSH_CIPHER_3DES)
 531                                         options.ciphers = "3des-cbc";
 532                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 533                                         options.ciphers = "blowfish-cbc";
 534                                 else
 535                                         options.ciphers = (char *)-1;
 536                         }
 537                         break;
 538                 case 'm':
 539                         if (mac_valid(optarg))
 540                                 options.macs = xstrdup(optarg);
 541                         else {
 542                                 fprintf(stderr, "Unknown mac type '%s'\n",
 543                                     optarg);
 544                                 exit(255);
 545                         }
 546                         break;
 547                 case 'M':
 548                         if (options.control_master == SSHCTL_MASTER_YES)
 549                                 options.control_master = SSHCTL_MASTER_ASK;
 550                         else
 551                                 options.control_master = SSHCTL_MASTER_YES;
 552                         break;
 553                 case 'p':
 554                         options.port = a2port(optarg);
 555                         if (options.port <= 0) {
 556                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 557                                 exit(255);
 558                         }
 559                         break;
 560                 case 'l':
 561                         options.user = optarg;
 562                         break;
 563
 564                 case 'L':
 565                         if (parse_forward(&fwd, optarg, 0, 0))
 566                                 add_local_forward(&options, &fwd);
 567                         else {
 568                                 fprintf(stderr,
 569                                     "Bad local forwarding specification '%s'\n",
 570                                     optarg);
 571                                 exit(255);
 572                         }
 573                         break;
 574
 575                 case 'R':
 576                         if (parse_forward(&fwd, optarg, 0, 1)) {
 577                                 add_remote_forward(&options, &fwd);
 578                         } else {
 579                                 fprintf(stderr,
 580                                     "Bad remote forwarding specification "
 581                                     "'%s'\n", optarg);
 582                                 exit(255);
 583                         }
 584                         break;
 585
 586                 case 'D':
 587                         if (parse_forward(&fwd, optarg, 1, 0)) {
 588                                 add_local_forward(&options, &fwd);
 589                         } else {
 590                                 fprintf(stderr,
 591                                     "Bad dynamic forwarding specification "
 592                                     "'%s'\n", optarg);
 593                                 exit(255);
 594                         }
 595                         break;
 596
 597                 case 'C':
 598                         options.compression = 1;
 599                         break;
 600                 case 'N':
 601                         no_shell_flag = 1;
 602                         options.request_tty = REQUEST_TTY_NO;
 603                         break;
 604                 case 'T':
 605                         options.request_tty = REQUEST_TTY_NO;
 606 #ifdef  NONE_CIPHER_ENABLED
 607                         /*
 608                          * Ensure that the user does not try to backdoor a
 609                          * NONE cipher switch on an interactive session by
 610                          * explicitly disabling it if the user asks for a
 611                          * session without a tty.
 612                          */
 613                         options.none_switch = 0;
 614 #endif
 615                         break;
 616                 case 'o':
 617                         dummy = 1;
 618                         line = xstrdup(optarg);
 619                         if (process_config_line(&options, host ? host : "",
 620                             line, "command-line", 0, &dummy, SSHCONF_USERCONF)
 621                             != 0)
 622                                 exit(255);
 623                         free(line);
 624                         break;
 625                 case 's':
 626                         subsystem_flag = 1;
 627                         break;
 628                 case 'S':
 629                         if (options.control_path != NULL)
 630                                 free(options.control_path);
 631                         options.control_path = xstrdup(optarg);
 632                         break;
 633                 case 'b':
 634                         options.bind_address = optarg;
 635                         break;
 636                 case 'F':
 637                         config = optarg;
 638                         break;
 639                 default:
 640                         usage();
 641                 }
 642         }
 643
 644         ac -= optind;
 645         av += optind;
 646
 647         if (ac > 0 && !host) {
 648                 if (strrchr(*av, '@')) {
 649                         p = xstrdup(*av);
 650                         cp = strrchr(p, '@');
 651                         if (cp == NULL || cp == p)
 652                                 usage();
 653                         options.user = p;
 654                         *cp = '\0';
 655                         host = ++cp;
 656                 } else
 657                         host = *av;
 658                 if (ac > 1) {
 659                         optind = optreset = 1;
 660                         goto again;
 661                 }
 662                 ac--, av++;
 663         }
 664
 665         /* Check that we got a host name. */
 666         if (!host)
 667                 usage();
 668
 669         OpenSSL_add_all_algorithms();
 670         ERR_load_crypto_strings();
 671
 672         /* Initialize the command to execute on remote host. */
 673         buffer_init(&command);
 674
 675         /*
 676          * Save the command to execute on the remote host in a buffer. There
 677          * is no limit on the length of the command, except by the maximum
 678          * packet size.  Also sets the tty flag if there is no command.
 679          */
 680         if (!ac) {
 681                 /* No command specified - execute shell on a tty. */
 682                 if (subsystem_flag) {
 683                         fprintf(stderr,
 684                             "You must specify a subsystem to invoke.\n");
 685                         usage();
 686                 }
 687         } else {
 688                 /* A command has been specified.  Store it into the buffer. */
 689                 for (i = 0; i < ac; i++) {
 690                         if (i)
 691                                 buffer_append(&command, " ", 1);
 692                         buffer_append(&command, av[i], strlen(av[i]));
 693                 }
 694         }
 695
 696         /* Cannot fork to background if no command. */
 697         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 698             !no_shell_flag)
 699                 fatal("Cannot fork into background without a command "
 700                     "to execute.");
 701
 702         /*
 703          * Initialize "log" output.  Since we are the client all output
 704          * goes to stderr unless otherwise specified by -y or -E.
 705          */
 706         if (use_syslog && logfile != NULL)
 707                 fatal("Can't specify both -y and -E");
 708         if (logfile != NULL) {
 709                 log_redirect_stderr_to(logfile);
 710                 free(logfile);
 711         }
 712         log_init(argv0,
 713             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 714             SYSLOG_FACILITY_USER, !use_syslog);
 715
 716         if (debug_flag)
 717                 logit("%s, %s", SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
 718
 719         /*
 720          * Read per-user configuration file.  Ignore the system wide config
 721          * file if the user specifies a config file on the command line.
 722          */
 723         if (config != NULL) {
 724                 if (strcasecmp(config, "none") != 0 &&
 725                     !read_config_file(config, host, &options, SSHCONF_USERCONF))
 726                         fatal("Can't open user config file %.100s: "
 727                             "%.100s", config, strerror(errno));
 728         } else {
 729                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 730                     _PATH_SSH_USER_CONFFILE);
 731                 if (r > 0 && (size_t)r < sizeof(buf))
 732                         (void)read_config_file(buf, host, &options,
 733                              SSHCONF_CHECKPERM|SSHCONF_USERCONF);
 734
 735                 /* Read systemwide configuration file after user config. */
 736                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
 737                     &options, 0);
 738         }
 739
 740         /* Fill configuration defaults. */
 741         fill_default_options(&options);
 742
 743         channel_set_af(options.address_family);
 744
 745         /* reinit */
 746         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 747
 748         if (options.request_tty == REQUEST_TTY_YES ||
 749             options.request_tty == REQUEST_TTY_FORCE)
 750                 tty_flag = 1;
 751
 752         /* Allocate a tty by default if no command specified. */
 753         if (buffer_len(&command) == 0)
 754                 tty_flag = options.request_tty != REQUEST_TTY_NO;
 755
 756         /* Force no tty */
 757         if (options.request_tty == REQUEST_TTY_NO || muxclient_command != 0)
 758                 tty_flag = 0;
 759         /* Do not allocate a tty if stdin is not a tty. */
 760         if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
 761             options.request_tty != REQUEST_TTY_FORCE) {
 762                 if (tty_flag)
 763                         logit("Pseudo-terminal will not be allocated because "
 764                             "stdin is not a terminal.");
 765                 tty_flag = 0;
 766         }
 767
 768         seed_rng();
 769
 770         if (options.user == NULL)
 771                 options.user = xstrdup(pw->pw_name);
 772
 773         /* Get default port if port has not been set. */
 774         if (options.port == 0) {
 775                 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
 776                 options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
 777         }
 778
 779         /* preserve host name given on command line for %n expansion */
 780         host_arg = host;
 781         if (options.hostname != NULL) {
 782                 host = percent_expand(options.hostname,
 783                     "h", host, (char *)NULL);
 784         }
 785
 786         if (gethostname(thishost, sizeof(thishost)) == -1)
 787                 fatal("gethostname: %s", strerror(errno));
 788         strlcpy(shorthost, thishost, sizeof(shorthost));
 789         shorthost[strcspn(thishost, ".")] = '\0';
 790         snprintf(portstr, sizeof(portstr), "%d", options.port);
 791
 792         if (options.local_command != NULL) {
 793                 debug3("expanding LocalCommand: %s", options.local_command);
 794                 cp = options.local_command;
 795                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
 796                     "h", host, "l", thishost, "n", host_arg, "r", options.user,
 797                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 798                     (char *)NULL);
 799                 debug3("expanded LocalCommand: %s", options.local_command);
 800                 free(cp);
 801         }
 802
 803         /* Find canonic host name. */
 804         if (strchr(host, '.') == 0) {
 805                 struct addrinfo hints;
 806                 struct addrinfo *ai = NULL;
 807                 int errgai;
 808                 memset(&hints, 0, sizeof(hints));
 809                 hints.ai_family = options.address_family;
 810                 hints.ai_flags = AI_CANONNAME;
 811                 hints.ai_socktype = SOCK_STREAM;
 812                 errgai = getaddrinfo(host, NULL, &hints, &ai);
 813                 if (errgai == 0) {
 814                         if (ai->ai_canonname != NULL)
 815                                 host = xstrdup(ai->ai_canonname);
 816                         freeaddrinfo(ai);
 817                 }
 818         }
 819
 820         /* force lowercase for hostkey matching */
 821         if (options.host_key_alias != NULL) {
 822                 for (p = options.host_key_alias; *p; p++)
 823                         if (isupper(*p))
 824                                 *p = (char)tolower(*p);
 825         }
 826
 827         if (options.proxy_command != NULL &&
 828             strcmp(options.proxy_command, "none") == 0) {
 829                 free(options.proxy_command);
 830                 options.proxy_command = NULL;
 831         }
 832         if (options.control_path != NULL &&
 833             strcmp(options.control_path, "none") == 0) {
 834                 free(options.control_path);
 835                 options.control_path = NULL;
 836         }
 837
 838         if (options.control_path != NULL) {
 839                 cp = tilde_expand_filename(options.control_path,
 840                     original_real_uid);
 841                 free(options.control_path);
 842                 options.control_path = percent_expand(cp, "h", host,
 843                     "l", thishost, "n", host_arg, "r", options.user,
 844                     "p", portstr, "u", pw->pw_name, "L", shorthost,
 845                     (char *)NULL);
 846                 free(cp);
 847         }
 848         if (muxclient_command != 0 && options.control_path == NULL)
 849                 fatal("No ControlPath specified for \"-O\" command");
 850         if (options.control_path != NULL)
 851                 muxclient(options.control_path);
 852
 853         timeout_ms = options.connection_timeout * 1000;
 854
 855         /* Open a connection to the remote host. */
 856         if (ssh_connect(host, &hostaddr, options.port,
 857             options.address_family, options.connection_attempts, &timeout_ms,
 858             options.tcp_keep_alive,
 859 #ifdef HAVE_CYGWIN
 860             options.use_privileged_port,
 861 #else
 862             original_effective_uid == 0 && options.use_privileged_port,
 863 #endif
 864             options.proxy_command) != 0)
 865                 exit(255);
 866
 867         if (timeout_ms > 0)
 868                 debug3("timeout: %d ms remain after connect", timeout_ms);
 869
 870         /*
 871          * If we successfully made the connection, load the host private key
 872          * in case we will need it later for combined rsa-rhosts
 873          * authentication. This must be done before releasing extra
 874          * privileges, because the file is only readable by root.
 875          * If we cannot access the private keys, load the public keys
 876          * instead and try to execute the ssh-keysign helper instead.
 877          */
 878         sensitive_data.nkeys = 0;
 879         sensitive_data.keys = NULL;
 880         sensitive_data.external_keysign = 0;
 881         if (options.rhosts_rsa_authentication ||
 882             options.hostbased_authentication) {
 883                 sensitive_data.nkeys = 7;
 884                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 885                     sizeof(Key));
 886                 for (i = 0; i < sensitive_data.nkeys; i++)
 887                         sensitive_data.keys[i] = NULL;
 888
 889                 PRIV_START;
 890                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 891                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
 892                 sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
 893                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 894 #ifdef OPENSSL_HAS_ECC
 895                 sensitive_data.keys[2] = key_load_private_cert(KEY_ECDSA,
 896                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
 897 #endif
 898                 sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
 899                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 900                 sensitive_data.keys[4] = key_load_private_type(KEY_DSA,
 901                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
 902 #ifdef OPENSSL_HAS_ECC
 903                 sensitive_data.keys[5] = key_load_private_type(KEY_ECDSA,
 904                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
 905 #endif
 906                 sensitive_data.keys[6] = key_load_private_type(KEY_RSA,
 907                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 908                 PRIV_END;
 909
 910                 if (options.hostbased_authentication == 1 &&
 911                     sensitive_data.keys[0] == NULL &&
 912                     sensitive_data.keys[4] == NULL &&
 913                     sensitive_data.keys[5] == NULL &&
 914                     sensitive_data.keys[6] == NULL) {
 915                         sensitive_data.keys[1] = key_load_cert(
 916                             _PATH_HOST_DSA_KEY_FILE);
 917 #ifdef OPENSSL_HAS_ECC
 918                         sensitive_data.keys[2] = key_load_cert(
 919                             _PATH_HOST_ECDSA_KEY_FILE);
 920 #endif
 921                         sensitive_data.keys[3] = key_load_cert(
 922                             _PATH_HOST_RSA_KEY_FILE);
 923                         sensitive_data.keys[4] = key_load_public(
 924                             _PATH_HOST_DSA_KEY_FILE, NULL);
 925 #ifdef OPENSSL_HAS_ECC
 926                         sensitive_data.keys[5] = key_load_public(
 927                             _PATH_HOST_ECDSA_KEY_FILE, NULL);
 928 #endif
 929                         sensitive_data.keys[6] = key_load_public(
 930                             _PATH_HOST_RSA_KEY_FILE, NULL);
 931                         sensitive_data.external_keysign = 1;
 932                 }
 933         }
 934         /*
 935          * Get rid of any extra privileges that we may have.  We will no
 936          * longer need them.  Also, extra privileges could make it very hard
 937          * to read identity files and other non-world-readable files from the
 938          * user's home directory if it happens to be on a NFS volume where
 939          * root is mapped to nobody.
 940          */
 941         if (original_effective_uid == 0) {
 942                 PRIV_START;
 943                 permanently_set_uid(pw);
 944         }
 945
 946         /*
 947          * Now that we are back to our own permissions, create ~/.ssh
 948          * directory if it doesn't already exist.
 949          */
 950         if (config == NULL) {
 951                 r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
 952                     strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 953                 if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
 954 #ifdef WITH_SELINUX
 955                         ssh_selinux_setfscreatecon(buf);
 956 #endif
 957                         if (mkdir(buf, 0700) < 0)
 958                                 error("Could not create directory '%.200s'.",
 959                                     buf);
 960 #ifdef WITH_SELINUX
 961                         ssh_selinux_setfscreatecon(NULL);
 962 #endif
 963                 }
 964         }
 965         /* load options.identity_files */
 966         load_public_identity_files();
 967
 968         /* Expand ~ in known host file names. */
 969         tilde_expand_paths(options.system_hostfiles,
 970             options.num_system_hostfiles);
 971         tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
 972
 973         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 974         signal(SIGCHLD, main_sigchld_handler);
 975
 976         /* Log into the remote system.  Never returns if the login fails. */
 977         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
 978             options.port, pw, timeout_ms);
 979
 980         if (packet_connection_is_on_socket()) {
 981                 verbose("Authenticated to %s ([%s]:%d).", host,
 982                     get_remote_ipaddr(), get_remote_port());
 983         } else {
 984                 verbose("Authenticated to %s (via proxy).", host);
 985         }
 986
 987         /* We no longer need the private host keys.  Clear them now. */
 988         if (sensitive_data.nkeys != 0) {
 989                 for (i = 0; i < sensitive_data.nkeys; i++) {
 990                         if (sensitive_data.keys[i] != NULL) {
 991                                 /* Destroys contents safely */
 992                                 debug3("clear hostkey %d", i);
 993                                 key_free(sensitive_data.keys[i]);
 994                                 sensitive_data.keys[i] = NULL;
 995                         }
 996                 }
 997                 free(sensitive_data.keys);
 998         }
 999         for (i = 0; i < options.num_identity_files; i++) {
1000                 free(options.identity_files[i]);
1001                 options.identity_files[i] = NULL;
1002                 if (options.identity_keys[i]) {
1003                         key_free(options.identity_keys[i]);
1004                         options.identity_keys[i] = NULL;
1005                 }
1006         }
1007
1008         exit_status = compat20 ? ssh_session2() : ssh_session();
1009         packet_close();
1010
1011         if (options.control_path != NULL && muxserver_sock != -1)
1012                 unlink(options.control_path);
1013
1014         /* Kill ProxyCommand if it is running. */
1015         ssh_kill_proxy_command();
1016
1017         return exit_status;
1018 }
1019
1020 static void
1021 control_persist_detach(void)
1022 {
1023         pid_t pid;
1024         int devnull;
1025
1026         debug("%s: backgrounding master process", __func__);
1027
1028         /*
1029          * master (current process) into the background, and make the
1030          * foreground process a client of the backgrounded master.
1031          */
1032         switch ((pid = fork())) {
1033         case -1:
1034                 fatal("%s: fork: %s", __func__, strerror(errno));
1035         case 0:
1036                 /* Child: master process continues mainloop */
1037                 break;
1038         default:
1039                 /* Parent: set up mux slave to connect to backgrounded master */
1040                 debug2("%s: background process is %ld", __func__, (long)pid);
1041                 stdin_null_flag = ostdin_null_flag;
1042                 options.request_tty = orequest_tty;
1043                 tty_flag = otty_flag;
1044                 close(muxserver_sock);
1045                 muxserver_sock = -1;
1046                 options.control_master = SSHCTL_MASTER_NO;
1047                 muxclient(options.control_path);
1048                 /* muxclient() doesn't return on success. */
1049                 fatal("Failed to connect to new control master");
1050         }
1051         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1052                 error("%s: open(\"/dev/null\"): %s", __func__,
1053                     strerror(errno));
1054         } else {
1055                 if (dup2(devnull, STDIN_FILENO) == -1 ||
1056                     dup2(devnull, STDOUT_FILENO) == -1)
1057                         error("%s: dup2: %s", __func__, strerror(errno));
1058                 if (devnull > STDERR_FILENO)
1059                         close(devnull);
1060         }
1061         daemon(1, 1);
1062         setproctitle("%s [mux]", options.control_path);
1063 }
1064
1065 /* Do fork() after authentication. Used by "ssh -f" */
1066 static void
1067 fork_postauth(void)
1068 {
1069         if (need_controlpersist_detach)
1070                 control_persist_detach();
1071         debug("forking to background");
1072         fork_after_authentication_flag = 0;
1073         if (daemon(1, 1) < 0)
1074                 fatal("daemon() failed: %.200s", strerror(errno));
1075 }
1076
1077 /* Callback for remote forward global requests */
1078 static void
1079 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
1080 {
1081         Forward *rfwd = (Forward *)ctxt;
1082
1083         /* XXX verbose() on failure? */
1084         debug("remote forward %s for: listen %d, connect %s:%d",
1085             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1086             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
1087         if (rfwd->listen_port == 0) {
1088                 if (type == SSH2_MSG_REQUEST_SUCCESS) {
1089                         rfwd->allocated_port = packet_get_int();
1090                         logit("Allocated port %u for remote forward to %s:%d",
1091                             rfwd->allocated_port,
1092                             rfwd->connect_host, rfwd->connect_port);
1093                         channel_update_permitted_opens(rfwd->handle,
1094                             rfwd->allocated_port);
1095                 } else {
1096                         channel_update_permitted_opens(rfwd->handle, -1);
1097                 }
1098         }
1099
1100         if (type == SSH2_MSG_REQUEST_FAILURE) {
1101                 if (options.exit_on_forward_failure)
1102                         fatal("Error: remote port forwarding failed for "
1103                             "listen port %d", rfwd->listen_port);
1104                 else
1105                         logit("Warning: remote port forwarding failed for "
1106                             "listen port %d", rfwd->listen_port);
1107         }
1108         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1109                 debug("All remote forwarding requests processed");
1110                 if (fork_after_authentication_flag)
1111                         fork_postauth();
1112         }
1113 }
1114
1115 static void
1116 client_cleanup_stdio_fwd(int id, void *arg)
1117 {
1118         debug("stdio forwarding: done");
1119         cleanup_exit(0);
1120 }
1121
1122 static void
1123 ssh_init_stdio_forwarding(void)
1124 {
1125         Channel *c;
1126         int in, out;
1127
1128         if (stdio_forward_host == NULL)
1129                 return;
1130         if (!compat20)
1131                 fatal("stdio forwarding require Protocol 2");
1132
1133         debug3("%s: %s:%d", __func__, stdio_forward_host, stdio_forward_port);
1134
1135         if ((in = dup(STDIN_FILENO)) < 0 ||
1136             (out = dup(STDOUT_FILENO)) < 0)
1137                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1138         if ((c = channel_connect_stdio_fwd(stdio_forward_host,
1139             stdio_forward_port, in, out)) == NULL)
1140                 fatal("%s: channel_connect_stdio_fwd failed", __func__);
1141         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1142 }
1143
1144 static void
1145 ssh_init_forwarding(void)
1146 {
1147         int success = 0;
1148         int i;
1149
1150         /* Initiate local TCP/IP port forwardings. */
1151         for (i = 0; i < options.num_local_forwards; i++) {
1152                 debug("Local connections to %.200s:%d forwarded to remote "
1153                     "address %.200s:%d",
1154                     (options.local_forwards[i].listen_host == NULL) ?
1155                     (options.gateway_ports ? "*" : "LOCALHOST") :
1156                     options.local_forwards[i].listen_host,
1157                     options.local_forwards[i].listen_port,
1158                     options.local_forwards[i].connect_host,
1159                     options.local_forwards[i].connect_port);
1160                 success += channel_setup_local_fwd_listener(
1161                     options.local_forwards[i].listen_host,
1162                     options.local_forwards[i].listen_port,
1163                     options.local_forwards[i].connect_host,
1164                     options.local_forwards[i].connect_port,
1165                     options.gateway_ports);
1166         }
1167         if (i > 0 && success != i && options.exit_on_forward_failure)
1168                 fatal("Could not request local forwarding.");
1169         if (i > 0 && success == 0)
1170                 error("Could not request local forwarding.");
1171
1172         /* Initiate remote TCP/IP port forwardings. */
1173         for (i = 0; i < options.num_remote_forwards; i++) {
1174                 debug("Remote connections from %.200s:%d forwarded to "
1175                     "local address %.200s:%d",
1176                     (options.remote_forwards[i].listen_host == NULL) ?
1177                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1178                     options.remote_forwards[i].listen_port,
1179                     options.remote_forwards[i].connect_host,
1180                     options.remote_forwards[i].connect_port);
1181                 options.remote_forwards[i].handle =
1182                     channel_request_remote_forwarding(
1183                     options.remote_forwards[i].listen_host,
1184                     options.remote_forwards[i].listen_port,
1185                     options.remote_forwards[i].connect_host,
1186                     options.remote_forwards[i].connect_port);
1187                 if (options.remote_forwards[i].handle < 0) {
1188                         if (options.exit_on_forward_failure)
1189                                 fatal("Could not request remote forwarding.");
1190                         else
1191                                 logit("Warning: Could not request remote "
1192                                     "forwarding.");
1193                 } else {
1194                         client_register_global_confirm(ssh_confirm_remote_forward,
1195                             &options.remote_forwards[i]);
1196                 }
1197         }
1198
1199         /* Initiate tunnel forwarding. */
1200         if (options.tun_open != SSH_TUNMODE_NO) {
1201                 if (client_request_tun_fwd(options.tun_open,
1202                     options.tun_local, options.tun_remote) == -1) {
1203                         if (options.exit_on_forward_failure)
1204                                 fatal("Could not request tunnel forwarding.");
1205                         else
1206                                 error("Could not request tunnel forwarding.");
1207                 }
1208         }
1209 }
1210
1211 static void
1212 check_agent_present(void)
1213 {
1214         if (options.forward_agent) {
1215                 /* Clear agent forwarding if we don't have an agent. */
1216                 if (!ssh_agent_present())
1217                         options.forward_agent = 0;
1218         }
1219 }
1220
1221 static int
1222 ssh_session(void)
1223 {
1224         int type;
1225         int interactive = 0;
1226         int have_tty = 0;
1227         struct winsize ws;
1228         char *cp;
1229         const char *display;
1230
1231         /* Enable compression if requested. */
1232         if (options.compression) {
1233                 debug("Requesting compression at level %d.",
1234                     options.compression_level);
1235
1236                 if (options.compression_level < 1 ||
1237                     options.compression_level > 9)
1238                         fatal("Compression level must be from 1 (fast) to "
1239                             "9 (slow, best).");
1240
1241                 /* Send the request. */
1242                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1243                 packet_put_int(options.compression_level);
1244                 packet_send();
1245                 packet_write_wait();
1246                 type = packet_read();
1247                 if (type == SSH_SMSG_SUCCESS)
1248                         packet_start_compression(options.compression_level);
1249                 else if (type == SSH_SMSG_FAILURE)
1250                         logit("Warning: Remote host refused compression.");
1251                 else
1252                         packet_disconnect("Protocol error waiting for "
1253                             "compression response.");
1254         }
1255         /* Allocate a pseudo tty if appropriate. */
1256         if (tty_flag) {
1257                 debug("Requesting pty.");
1258
1259                 /* Start the packet. */
1260                 packet_start(SSH_CMSG_REQUEST_PTY);
1261
1262                 /* Store TERM in the packet.  There is no limit on the
1263                    length of the string. */
1264                 cp = getenv("TERM");
1265                 if (!cp)
1266                         cp = "";
1267                 packet_put_cstring(cp);
1268
1269                 /* Store window size in the packet. */
1270                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1271                         memset(&ws, 0, sizeof(ws));
1272                 packet_put_int((u_int)ws.ws_row);
1273                 packet_put_int((u_int)ws.ws_col);
1274                 packet_put_int((u_int)ws.ws_xpixel);
1275                 packet_put_int((u_int)ws.ws_ypixel);
1276
1277                 /* Store tty modes in the packet. */
1278                 tty_make_modes(fileno(stdin), NULL);
1279
1280                 /* Send the packet, and wait for it to leave. */
1281                 packet_send();
1282                 packet_write_wait();
1283
1284                 /* Read response from the server. */
1285                 type = packet_read();
1286                 if (type == SSH_SMSG_SUCCESS) {
1287                         interactive = 1;
1288                         have_tty = 1;
1289                 } else if (type == SSH_SMSG_FAILURE)
1290                         logit("Warning: Remote host failed or refused to "
1291                             "allocate a pseudo tty.");
1292                 else
1293                         packet_disconnect("Protocol error waiting for pty "
1294                             "request response.");
1295         }
1296         /* Request X11 forwarding if enabled and DISPLAY is set. */
1297         display = getenv("DISPLAY");
1298         if (options.forward_x11 && display != NULL) {
1299                 char *proto, *data;
1300                 /* Get reasonable local authentication information. */
1301                 client_x11_get_proto(display, options.xauth_location,
1302                     options.forward_x11_trusted,
1303                     options.forward_x11_timeout,
1304                     &proto, &data);
1305                 /* Request forwarding with authentication spoofing. */
1306                 debug("Requesting X11 forwarding with authentication "
1307                     "spoofing.");
1308                 x11_request_forwarding_with_spoofing(0, display, proto,
1309                     data, 0);
1310                 /* Read response from the server. */
1311                 type = packet_read();
1312                 if (type == SSH_SMSG_SUCCESS) {
1313                         interactive = 1;
1314                 } else if (type == SSH_SMSG_FAILURE) {
1315                         logit("Warning: Remote host denied X11 forwarding.");
1316                 } else {
1317                         packet_disconnect("Protocol error waiting for X11 "
1318                             "forwarding");
1319                 }
1320         }
1321         /* Tell the packet module whether this is an interactive session. */
1322         packet_set_interactive(interactive,
1323             options.ip_qos_interactive, options.ip_qos_bulk);
1324
1325         /* Request authentication agent forwarding if appropriate. */
1326         check_agent_present();
1327
1328         if (options.forward_agent) {
1329                 debug("Requesting authentication agent forwarding.");
1330                 auth_request_forwarding();
1331
1332                 /* Read response from the server. */
1333                 type = packet_read();
1334                 packet_check_eom();
1335                 if (type != SSH_SMSG_SUCCESS)
1336                         logit("Warning: Remote host denied authentication agent forwarding.");
1337         }
1338
1339         /* Initiate port forwardings. */
1340         ssh_init_stdio_forwarding();
1341         ssh_init_forwarding();
1342
1343         /* Execute a local command */
1344         if (options.local_command != NULL &&
1345             options.permit_local_command)
1346                 ssh_local_cmd(options.local_command);
1347
1348         /*
1349          * If requested and we are not interested in replies to remote
1350          * forwarding requests, then let ssh continue in the background.
1351          */
1352         if (fork_after_authentication_flag) {
1353                 if (options.exit_on_forward_failure &&
1354                     options.num_remote_forwards > 0) {
1355                         debug("deferring postauth fork until remote forward "
1356                             "confirmation received");
1357                 } else
1358                         fork_postauth();
1359         }
1360
1361         /*
1362          * If a command was specified on the command line, execute the
1363          * command now. Otherwise request the server to start a shell.
1364          */
1365         if (buffer_len(&command) > 0) {
1366                 int len = buffer_len(&command);
1367                 if (len > 900)
1368                         len = 900;
1369                 debug("Sending command: %.*s", len,
1370                     (u_char *)buffer_ptr(&command));
1371                 packet_start(SSH_CMSG_EXEC_CMD);
1372                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1373                 packet_send();
1374                 packet_write_wait();
1375         } else {
1376                 debug("Requesting shell.");
1377                 packet_start(SSH_CMSG_EXEC_SHELL);
1378                 packet_send();
1379                 packet_write_wait();
1380         }
1381
1382         /* Enter the interactive session. */
1383         return client_loop(have_tty, tty_flag ?
1384             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1385 }
1386
1387 /* request pty/x11/agent/tcpfwd/shell for channel */
1388 static void
1389 ssh_session2_setup(int id, int success, void *arg)
1390 {
1391         extern char **environ;
1392         const char *display;
1393         int interactive = tty_flag;
1394
1395         if (!success)
1396                 return; /* No need for error message, channels code sens one */
1397
1398         display = getenv("DISPLAY");
1399         if (options.forward_x11 && display != NULL) {
1400                 char *proto, *data;
1401                 /* Get reasonable local authentication information. */
1402                 client_x11_get_proto(display, options.xauth_location,
1403                     options.forward_x11_trusted,
1404                     options.forward_x11_timeout, &proto, &data);
1405                 /* Request forwarding with authentication spoofing. */
1406                 debug("Requesting X11 forwarding with authentication "
1407                     "spoofing.");
1408                 x11_request_forwarding_with_spoofing(id, display, proto,
1409                     data, 1);
1410                 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
1411                 /* XXX exit_on_forward_failure */
1412                 interactive = 1;
1413         }
1414
1415         check_agent_present();
1416         if (options.forward_agent) {
1417                 debug("Requesting authentication agent forwarding.");
1418                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1419                 packet_send();
1420         }
1421
1422         /* Tell the packet module whether this is an interactive session. */
1423         packet_set_interactive(interactive,
1424             options.ip_qos_interactive, options.ip_qos_bulk);
1425
1426         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1427             NULL, fileno(stdin), &command, environ);
1428 }
1429
1430 /* open new channel for a session */
1431 static int
1432 ssh_session2_open(void)
1433 {
1434         Channel *c;
1435         int window, packetmax, in, out, err;
1436
1437         if (stdin_null_flag) {
1438                 in = open(_PATH_DEVNULL, O_RDONLY);
1439         } else {
1440                 in = dup(STDIN_FILENO);
1441         }
1442         out = dup(STDOUT_FILENO);
1443         err = dup(STDERR_FILENO);
1444
1445         if (in < 0 || out < 0 || err < 0)
1446                 fatal("dup() in/out/err failed");
1447
1448         /* enable nonblocking unless tty */
1449         if (!isatty(in))
1450                 set_nonblock(in);
1451         if (!isatty(out))
1452                 set_nonblock(out);
1453         if (!isatty(err))
1454                 set_nonblock(err);
1455
1456         /*
1457          * We need to check to see what to do about buffer sizes here.
1458          * - In an HPN to non-HPN connection we want to limit the window size to
1459          *   something reasonable in case the far side has the large window bug.
1460          * - In an HPN to HPN connection we want to use the max window size but
1461          *   allow the user to override it.
1462          * - Lastly if HPN is disabled then use the ssh standard window size.
1463          *
1464          * We cannot just do a getsockopt() here and set the ssh window to that
1465          * as in case of autotuning of socket buffers the window would get stuck
1466          * at the initial buffer size, generally less than 96k.  Therefore we
1467          * need to set the maximum ssh window size to the maximum HPN buffer
1468          * size unless the user has set TcpRcvBufPoll to no.  In that case we
1469          * can just set the window to the minimum of HPN buffer size and TCP
1470          * receive buffer size.
1471          */
1472         if (tty_flag)
1473                 options.hpn_buffer_size = CHAN_SES_WINDOW_DEFAULT;
1474         else
1475                 options.hpn_buffer_size = CHAN_HPN_MIN_WINDOW_DEFAULT;
1476
1477         if (datafellows & SSH_BUG_LARGEWINDOW) {
1478                 debug("HPN to Non-HPN Connection");
1479         } else if (options.tcp_rcv_buf_poll <= 0) {
1480                 sock_get_rcvbuf(&options.hpn_buffer_size, 0);
1481                 debug("HPNBufferSize set to TCP RWIN: %d",
1482                     options.hpn_buffer_size);
1483         } else if (options.tcp_rcv_buf > 0) {
1484                 sock_get_rcvbuf(&options.hpn_buffer_size,
1485                     options.tcp_rcv_buf);
1486                 debug("HPNBufferSize set to user TCPRcvBuf: %d",
1487                     options.hpn_buffer_size);
1488         }
1489         debug("Final hpn_buffer_size = %d", options.hpn_buffer_size);
1490         channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1491         window = options.hpn_buffer_size;
1492
1493         packetmax = CHAN_SES_PACKET_DEFAULT;
1494         if (tty_flag) {
1495                 window = CHAN_SES_WINDOW_DEFAULT;
1496                 window >>= 1;
1497                 packetmax >>= 1;
1498         }
1499         c = channel_new(
1500             "session", SSH_CHANNEL_OPENING, in, out, err,
1501             window, packetmax, CHAN_EXTENDED_WRITE,
1502             "client-session", /*nonblock*/0);
1503         if (!options.hpn_disabled && options.tcp_rcv_buf_poll > 0) {
1504                 c->dynamic_window = 1;
1505                 debug("Enabled Dynamic Window Scaling\n");
1506         }
1507
1508         debug3("ssh_session2_open: channel_new: %d", c->self);
1509
1510         channel_send_open(c->self);
1511         if (!no_shell_flag)
1512                 channel_register_open_confirm(c->self,
1513                     ssh_session2_setup, NULL);
1514
1515         return c->self;
1516 }
1517
1518 static int
1519 ssh_session2(void)
1520 {
1521         int id = -1;
1522
1523         /* XXX should be pre-session */
1524         if (!options.control_persist)
1525                 ssh_init_stdio_forwarding();
1526         ssh_init_forwarding();
1527
1528         /* Start listening for multiplex clients */
1529         muxserver_listen();
1530
1531         /*
1532          * If we are in control persist mode and have a working mux listen
1533          * socket, then prepare to background ourselves and have a foreground
1534          * client attach as a control slave.
1535          * NB. we must save copies of the flags that we override for
1536          * the backgrounding, since we defer attachment of the slave until
1537          * after the connection is fully established (in particular,
1538          * async rfwd replies have been received for ExitOnForwardFailure).
1539          */
1540         if (options.control_persist && muxserver_sock != -1) {
1541                 ostdin_null_flag = stdin_null_flag;
1542                 ono_shell_flag = no_shell_flag;
1543                 orequest_tty = options.request_tty;
1544                 otty_flag = tty_flag;
1545                 stdin_null_flag = 1;
1546                 no_shell_flag = 1;
1547                 tty_flag = 0;
1548                 if (!fork_after_authentication_flag)
1549                         need_controlpersist_detach = 1;
1550                 fork_after_authentication_flag = 1;
1551         }
1552         /*
1553          * ControlPersist mux listen socket setup failed, attempt the
1554          * stdio forward setup that we skipped earlier.
1555          */
1556         if (options.control_persist && muxserver_sock == -1)
1557                 ssh_init_stdio_forwarding();
1558
1559         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1560                 id = ssh_session2_open();
1561         else {
1562                 packet_set_interactive(
1563                     options.control_master == SSHCTL_MASTER_NO,
1564                     options.ip_qos_interactive, options.ip_qos_bulk);
1565         }
1566
1567         /* If we don't expect to open a new session, then disallow it */
1568         if (options.control_master == SSHCTL_MASTER_NO &&
1569             (datafellows & SSH_NEW_OPENSSH)) {
1570                 debug("Requesting no-more-sessions@openssh.com");
1571                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1572                 packet_put_cstring("no-more-sessions@openssh.com");
1573                 packet_put_char(0);
1574                 packet_send();
1575         }
1576
1577         /* Execute a local command */
1578         if (options.local_command != NULL &&
1579             options.permit_local_command)
1580                 ssh_local_cmd(options.local_command);
1581
1582         /*
1583          * If requested and we are not interested in replies to remote
1584          * forwarding requests, then let ssh continue in the background.
1585          */
1586         if (fork_after_authentication_flag) {
1587                 if (options.exit_on_forward_failure &&
1588                     options.num_remote_forwards > 0) {
1589                         debug("deferring postauth fork until remote forward "
1590                             "confirmation received");
1591                 } else
1592                         fork_postauth();
1593         }
1594
1595         if (options.use_roaming)
1596                 request_roaming();
1597
1598         return client_loop(tty_flag, tty_flag ?
1599             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1600 }
1601
1602 static void
1603 load_public_identity_files(void)
1604 {
1605         char *filename, *cp, thishost[NI_MAXHOST];
1606         char *pwdir = NULL, *pwname = NULL;
1607         int i = 0;
1608         Key *public;
1609         struct passwd *pw;
1610         u_int n_ids;
1611         char *identity_files[SSH_MAX_IDENTITY_FILES];
1612         Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1613 #ifdef ENABLE_PKCS11
1614         Key **keys;
1615         int nkeys;
1616 #endif /* PKCS11 */
1617
1618         n_ids = 0;
1619         bzero(identity_files, sizeof(identity_files));
1620         bzero(identity_keys, sizeof(identity_keys));
1621
1622 #ifdef ENABLE_PKCS11
1623         if (options.pkcs11_provider != NULL &&
1624             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1625             (pkcs11_init(!options.batch_mode) == 0) &&
1626             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1627             &keys)) > 0) {
1628                 for (i = 0; i < nkeys; i++) {
1629                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1630                                 key_free(keys[i]);
1631                                 continue;
1632                         }
1633                         identity_keys[n_ids] = keys[i];
1634                         identity_files[n_ids] =
1635                             xstrdup(options.pkcs11_provider); /* XXX */
1636                         n_ids++;
1637                 }
1638                 free(keys);
1639         }
1640 #endif /* ENABLE_PKCS11 */
1641         if ((pw = getpwuid(original_real_uid)) == NULL)
1642                 fatal("load_public_identity_files: getpwuid failed");
1643         pwname = xstrdup(pw->pw_name);
1644         pwdir = xstrdup(pw->pw_dir);
1645         if (gethostname(thishost, sizeof(thishost)) == -1)
1646                 fatal("load_public_identity_files: gethostname: %s",
1647                     strerror(errno));
1648         for (i = 0; i < options.num_identity_files; i++) {
1649                 if (n_ids >= SSH_MAX_IDENTITY_FILES ||
1650                     strcasecmp(options.identity_files[i], "none") == 0) {
1651                         free(options.identity_files[i]);
1652                         continue;
1653                 }
1654                 cp = tilde_expand_filename(options.identity_files[i],
1655                     original_real_uid);
1656                 filename = percent_expand(cp, "d", pwdir,
1657                     "u", pwname, "l", thishost, "h", host,
1658                     "r", options.user, (char *)NULL);
1659                 free(cp);
1660                 public = key_load_public(filename, NULL);
1661                 debug("identity file %s type %d", filename,
1662                     public ? public->type : -1);
1663                 free(options.identity_files[i]);
1664                 identity_files[n_ids] = filename;
1665                 identity_keys[n_ids] = public;
1666
1667                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
1668                         continue;
1669
1670                 /* Try to add the certificate variant too */
1671                 xasprintf(&cp, "%s-cert", filename);
1672                 public = key_load_public(cp, NULL);
1673                 debug("identity file %s type %d", cp,
1674                     public ? public->type : -1);
1675                 if (public == NULL) {
1676                         free(cp);
1677                         continue;
1678                 }
1679                 if (!key_is_cert(public)) {
1680                         debug("%s: key %s type %s is not a certificate",
1681                             __func__, cp, key_type(public));
1682                         key_free(public);
1683                         free(cp);
1684                         continue;
1685                 }
1686                 identity_keys[n_ids] = public;
1687                 /* point to the original path, most likely the private key */
1688                 identity_files[n_ids] = xstrdup(filename);
1689                 n_ids++;
1690         }
1691         options.num_identity_files = n_ids;
1692         memcpy(options.identity_files, identity_files, sizeof(identity_files));
1693         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
1694
1695         bzero(pwname, strlen(pwname));
1696         free(pwname);
1697         bzero(pwdir, strlen(pwdir));
1698         free(pwdir);
1699 }
1700
1701 static void
1702 main_sigchld_handler(int sig)
1703 {
1704         int save_errno = errno;
1705         pid_t pid;
1706         int status;
1707
1708         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
1709             (pid < 0 && errno == EINTR))
1710                 ;
1711
1712         signal(sig, main_sigchld_handler);
1713         errno = save_errno;
1714 }
1715