crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.401 2014/02/26 20:18:37 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * Ssh client program.  This program can be used to log into a remote machine.
   7  * The software supports strong authentication, encryption, and forwarding
   8  * of X11, TCP/IP, and authentication connections.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  17  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  18  *
  19  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  20  * in Canada (German citizen).
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the above copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  *
  31  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  32  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  34  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  35  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  36  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  37  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  38  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  39  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  40  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  41  */
  42
  43 #include "includes.h"
  44 __RCSID("$FreeBSD$");
  45
  46 #include <sys/types.h>
  47 #ifdef HAVE_SYS_STAT_H
  48 # include <sys/stat.h>
  49 #endif
  50 #include <sys/resource.h>
  51 #include <sys/ioctl.h>
  52 #include <sys/param.h>
  53 #include <sys/socket.h>
  54 #include <sys/wait.h>
  55
  56 #include <ctype.h>
  57 #include <errno.h>
  58 #include <fcntl.h>
  59 #include <netdb.h>
  60 #ifdef HAVE_PATHS_H
  61 #include <paths.h>
  62 #endif
  63 #include <pwd.h>
  64 #include <signal.h>
  65 #include <stdarg.h>
  66 #include <stddef.h>
  67 #include <stdio.h>
  68 #include <stdlib.h>
  69 #include <string.h>
  70 #include <unistd.h>
  71
  72 #include <netinet/in.h>
  73 #include <arpa/inet.h>
  74
  75 #include <openssl/evp.h>
  76 #include <openssl/err.h>
  77 #include "openbsd-compat/openssl-compat.h"
  78 #include "openbsd-compat/sys-queue.h"
  79
  80 #include "xmalloc.h"
  81 #include "ssh.h"
  82 #include "ssh1.h"
  83 #include "ssh2.h"
  84 #include "canohost.h"
  85 #include "compat.h"
  86 #include "cipher.h"
  87 #include "packet.h"
  88 #include "buffer.h"
  89 #include "channels.h"
  90 #include "key.h"
  91 #include "authfd.h"
  92 #include "authfile.h"
  93 #include "pathnames.h"
  94 #include "dispatch.h"
  95 #include "clientloop.h"
  96 #include "log.h"
  97 #include "readconf.h"
  98 #include "sshconnect.h"
  99 #include "misc.h"
 100 #include "kex.h"
 101 #include "mac.h"
 102 #include "sshpty.h"
 103 #include "match.h"
 104 #include "msg.h"
 105 #include "uidswap.h"
 106 #include "roaming.h"
 107 #include "version.h"
 108
 109 #ifdef ENABLE_PKCS11
 110 #include "ssh-pkcs11.h"
 111 #endif
 112
 113 extern char *__progname;
 114
 115 /* Saves a copy of argv for setproctitle emulation */
 116 #ifndef HAVE_SETPROCTITLE
 117 static char **saved_av;
 118 #endif
 119
 120 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 121 int debug_flag = 0;
 122
 123 /* Flag indicating whether a tty should be requested */
 124 int tty_flag = 0;
 125
 126 /* don't exec a shell */
 127 int no_shell_flag = 0;
 128
 129 /*
 130  * Flag indicating that nothing should be read from stdin.  This can be set
 131  * on the command line.
 132  */
 133 int stdin_null_flag = 0;
 134
 135 /*
 136  * Flag indicating that the current process should be backgrounded and
 137  * a new slave launched in the foreground for ControlPersist.
 138  */
 139 int need_controlpersist_detach = 0;
 140
 141 /* Copies of flags for ControlPersist foreground slave */
 142 int ostdin_null_flag, ono_shell_flag, otty_flag, orequest_tty;
 143
 144 /*
 145  * Flag indicating that ssh should fork after authentication.  This is useful
 146  * so that the passphrase can be entered manually, and then ssh goes to the
 147  * background.
 148  */
 149 int fork_after_authentication_flag = 0;
 150
 151 /* forward stdio to remote host and port */
 152 char *stdio_forward_host = NULL;
 153 int stdio_forward_port = 0;
 154
 155 /*
 156  * General data structure for command line options and options configurable
 157  * in configuration files.  See readconf.h.
 158  */
 159 Options options;
 160
 161 /* optional user configfile */
 162 char *config = NULL;
 163
 164 /*
 165  * Name of the host we are connecting to.  This is the name given on the
 166  * command line, or the HostName specified for the user-supplied name in a
 167  * configuration file.
 168  */
 169 char *host;
 170
 171 /* socket address the host resolves to */
 172 struct sockaddr_storage hostaddr;
 173
 174 /* Private host keys. */
 175 Sensitive sensitive_data;
 176
 177 /* Original real UID. */
 178 uid_t original_real_uid;
 179 uid_t original_effective_uid;
 180
 181 /* command to be executed */
 182 Buffer command;
 183
 184 /* Should we execute a command or invoke a subsystem? */
 185 int subsystem_flag = 0;
 186
 187 /* # of replies received for global requests */
 188 static int remote_forward_confirms_received = 0;
 189
 190 /* mux.c */
 191 extern int muxserver_sock;
 192 extern u_int muxclient_command;
 193
 194 /* Prints a help message to the user.  This function never returns. */
 195
 196 static void
 197 usage(void)
 198 {
 199         fprintf(stderr,
 200 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
 201 "           [-D [bind_address:]port] [-E log_file] [-e escape_char]\n"
 202 "           [-F configfile] [-I pkcs11] [-i identity_file]\n"
 203 "           [-L [bind_address:]port:host:hostport] [-l login_name] [-m mac_spec]\n"
 204 "           [-O ctl_cmd] [-o option] [-p port]\n"
 205 "           [-Q cipher | cipher-auth | mac | kex | key]\n"
 206 "           [-R [bind_address:]port:host:hostport] [-S ctl_path] [-W host:port]\n"
 207 "           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
 208         );
 209         exit(255);
 210 }
 211
 212 static int ssh_session(void);
 213 static int ssh_session2(void);
 214 static void load_public_identity_files(void);
 215 static void main_sigchld_handler(int);
 216
 217 /* from muxclient.c */
 218 void muxclient(const char *);
 219 void muxserver_listen(void);
 220
 221 /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
 222 static void
 223 tilde_expand_paths(char **paths, u_int num_paths)
 224 {
 225         u_int i;
 226         char *cp;
 227
 228         for (i = 0; i < num_paths; i++) {
 229                 cp = tilde_expand_filename(paths[i], original_real_uid);
 230                 free(paths[i]);
 231                 paths[i] = cp;
 232         }
 233 }
 234
 235 /*
 236  * Attempt to resolve a host name / port to a set of addresses and
 237  * optionally return any CNAMEs encountered along the way.
 238  * Returns NULL on failure.
 239  * NB. this function must operate with a options having undefined members.
 240  */
 241 static struct addrinfo *
 242 resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
 243 {
 244         char strport[NI_MAXSERV];
 245         struct addrinfo hints, *res;
 246         int gaierr, loglevel = SYSLOG_LEVEL_DEBUG1;
 247
 248         if (port <= 0)
 249                 port = default_ssh_port();
 250
 251         snprintf(strport, sizeof strport, "%u", port);
 252         memset(&hints, 0, sizeof(hints));
 253         hints.ai_family = options.address_family == -1 ?
 254             AF_UNSPEC : options.address_family;
 255         hints.ai_socktype = SOCK_STREAM;
 256         if (cname != NULL)
 257                 hints.ai_flags = AI_CANONNAME;
 258         if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
 259                 if (logerr || (gaierr != EAI_NONAME && gaierr != EAI_NODATA))
 260                         loglevel = SYSLOG_LEVEL_ERROR;
 261                 do_log2(loglevel, "%s: Could not resolve hostname %.100s: %s",
 262                     __progname, name, ssh_gai_strerror(gaierr));
 263                 return NULL;
 264         }
 265         if (cname != NULL && res->ai_canonname != NULL) {
 266                 if (strlcpy(cname, res->ai_canonname, clen) >= clen) {
 267                         error("%s: host \"%s\" cname \"%s\" too long (max %lu)",
 268                             __func__, name,  res->ai_canonname, (u_long)clen);
 269                         if (clen > 0)
 270                                 *cname = '\0';
 271                 }
 272         }
 273         return res;
 274 }
 275
 276 /*
 277  * Check whether the cname is a permitted replacement for the hostname
 278  * and perform the replacement if it is.
 279  * NB. this function must operate with a options having undefined members.
 280  */
 281 static int
 282 check_follow_cname(char **namep, const char *cname)
 283 {
 284         int i;
 285         struct allowed_cname *rule;
 286
 287         if (*cname == '\0' || options.num_permitted_cnames == 0 ||
 288             strcmp(*namep, cname) == 0)
 289                 return 0;
 290         if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
 291                 return 0;
 292         /*
 293          * Don't attempt to canonicalize names that will be interpreted by
 294          * a proxy unless the user specifically requests so.
 295          */
 296         if (!option_clear_or_none(options.proxy_command) &&
 297             options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
 298                 return 0;
 299         debug3("%s: check \"%s\" CNAME \"%s\"", __func__, *namep, cname);
 300         for (i = 0; i < options.num_permitted_cnames; i++) {
 301                 rule = options.permitted_cnames + i;
 302                 if (match_pattern_list(*namep, rule->source_list,
 303                     strlen(rule->source_list), 1) != 1 ||
 304                     match_pattern_list(cname, rule->target_list,
 305                     strlen(rule->target_list), 1) != 1)
 306                         continue;
 307                 verbose("Canonicalized DNS aliased hostname "
 308                     "\"%s\" => \"%s\"", *namep, cname);
 309                 free(*namep);
 310                 *namep = xstrdup(cname);
 311                 return 1;
 312         }
 313         return 0;
 314 }
 315
 316 /*
 317  * Attempt to resolve the supplied hostname after applying the user's
 318  * canonicalization rules. Returns the address list for the host or NULL
 319  * if no name was found after canonicalization.
 320  * NB. this function must operate with a options having undefined members.
 321  */
 322 static struct addrinfo *
 323 resolve_canonicalize(char **hostp, int port)
 324 {
 325         int i, ndots;
 326         char *cp, *fullhost, cname_target[NI_MAXHOST];
 327         struct addrinfo *addrs;
 328
 329         if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
 330                 return NULL;
 331
 332         /*
 333          * Don't attempt to canonicalize names that will be interpreted by
 334          * a proxy unless the user specifically requests so.
 335          */
 336         if (!option_clear_or_none(options.proxy_command) &&
 337             options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
 338                 return NULL;
 339
 340         /* Don't apply canonicalization to sufficiently-qualified hostnames */
 341         ndots = 0;
 342         for (cp = *hostp; *cp != '\0'; cp++) {
 343                 if (*cp == '.')
 344                         ndots++;
 345         }
 346         if (ndots > options.canonicalize_max_dots) {
 347                 debug3("%s: not canonicalizing hostname \"%s\" (max dots %d)",
 348                     __func__, *hostp, options.canonicalize_max_dots);
 349                 return NULL;
 350         }
 351         /* Attempt each supplied suffix */
 352         for (i = 0; i < options.num_canonical_domains; i++) {
 353                 *cname_target = '\0';
 354                 xasprintf(&fullhost, "%s.%s.", *hostp,
 355                     options.canonical_domains[i]);
 356                 debug3("%s: attempting \"%s\" => \"%s\"", __func__,
 357                     *hostp, fullhost);
 358                 if ((addrs = resolve_host(fullhost, port, 0,
 359                     cname_target, sizeof(cname_target))) == NULL) {
 360                         free(fullhost);
 361                         continue;
 362                 }
 363                 /* Remove trailing '.' */
 364                 fullhost[strlen(fullhost) - 1] = '\0';
 365                 /* Follow CNAME if requested */
 366                 if (!check_follow_cname(&fullhost, cname_target)) {
 367                         debug("Canonicalized hostname \"%s\" => \"%s\"",
 368                             *hostp, fullhost);
 369                 }
 370                 free(*hostp);
 371                 *hostp = fullhost;
 372                 return addrs;
 373         }
 374         if (!options.canonicalize_fallback_local)
 375                 fatal("%s: Could not resolve host \"%s\"", __progname, *hostp);
 376         debug2("%s: host %s not found in any suffix", __func__, *hostp);
 377         return NULL;
 378 }
 379
 380 /*
 381  * Read per-user configuration file.  Ignore the system wide config
 382  * file if the user specifies a config file on the command line.
 383  */
 384 static void
 385 process_config_files(struct passwd *pw)
 386 {
 387         char buf[MAXPATHLEN];
 388         int r;
 389
 390         if (config != NULL) {
 391                 if (strcasecmp(config, "none") != 0 &&
 392                     !read_config_file(config, pw, host, &options,
 393                     SSHCONF_USERCONF))
 394                         fatal("Can't open user config file %.100s: "
 395                             "%.100s", config, strerror(errno));
 396         } else {
 397                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 398                     _PATH_SSH_USER_CONFFILE);
 399                 if (r > 0 && (size_t)r < sizeof(buf))
 400                         (void)read_config_file(buf, pw, host, &options,
 401                              SSHCONF_CHECKPERM|SSHCONF_USERCONF);
 402
 403                 /* Read systemwide configuration file after user config. */
 404                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, host,
 405                     &options, 0);
 406         }
 407 }
 408
 409 /*
 410  * Main program for the ssh client.
 411  */
 412 int
 413 main(int ac, char **av)
 414 {
 415         int i, r, opt, exit_status, use_syslog;
 416         char *p, *cp, *line, *argv0, buf[MAXPATHLEN], *host_arg, *logfile;
 417         char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
 418         char cname[NI_MAXHOST];
 419         struct stat st;
 420         struct passwd *pw;
 421         int timeout_ms;
 422         extern int optind, optreset;
 423         extern char *optarg;
 424         Forward fwd;
 425         struct addrinfo *addrs = NULL;
 426
 427         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 428         sanitise_stdfd();
 429
 430         __progname = ssh_get_progname(av[0]);
 431
 432 #ifndef HAVE_SETPROCTITLE
 433         /* Prepare for later setproctitle emulation */
 434         /* Save argv so it isn't clobbered by setproctitle() emulation */
 435         saved_av = xcalloc(ac + 1, sizeof(*saved_av));
 436         for (i = 0; i < ac; i++)
 437                 saved_av[i] = xstrdup(av[i]);
 438         saved_av[i] = NULL;
 439         compat_init_setproctitle(ac, av);
 440         av = saved_av;
 441 #endif
 442
 443         /*
 444          * Discard other fds that are hanging around. These can cause problem
 445          * with backgrounded ssh processes started by ControlPersist.
 446          */
 447         closefrom(STDERR_FILENO + 1);
 448
 449         /*
 450          * Save the original real uid.  It will be needed later (uid-swapping
 451          * may clobber the real uid).
 452          */
 453         original_real_uid = getuid();
 454         original_effective_uid = geteuid();
 455
 456         /*
 457          * Use uid-swapping to give up root privileges for the duration of
 458          * option processing.  We will re-instantiate the rights when we are
 459          * ready to create the privileged port, and will permanently drop
 460          * them when the port has been created (actually, when the connection
 461          * has been made, as we may need to create the port several times).
 462          */
 463         PRIV_END;
 464
 465 #ifdef HAVE_SETRLIMIT
 466         /* If we are installed setuid root be careful to not drop core. */
 467         if (original_real_uid != original_effective_uid) {
 468                 struct rlimit rlim;
 469                 rlim.rlim_cur = rlim.rlim_max = 0;
 470                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 471                         fatal("setrlimit failed: %.100s", strerror(errno));
 472         }
 473 #endif
 474         /* Get user data. */
 475         pw = getpwuid(original_real_uid);
 476         if (!pw) {
 477                 logit("No user exists for uid %lu", (u_long)original_real_uid);
 478                 exit(255);
 479         }
 480         /* Take a copy of the returned structure. */
 481         pw = pwcopy(pw);
 482
 483         /*
 484          * Set our umask to something reasonable, as some files are created
 485          * with the default umask.  This will make them world-readable but
 486          * writable only by the owner, which is ok for all files for which we
 487          * don't set the modes explicitly.
 488          */
 489         umask(022);
 490
 491         /*
 492          * Initialize option structure to indicate that no values have been
 493          * set.
 494          */
 495         initialize_options(&options);
 496
 497         /* Parse command-line arguments. */
 498         host = NULL;
 499         use_syslog = 0;
 500         logfile = NULL;
 501         argv0 = av[0];
 502
 503  again:
 504         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 505             "ACD:E:F:I:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) {
 506                 switch (opt) {
 507                 case '1':
 508                         options.protocol = SSH_PROTO_1;
 509                         break;
 510                 case '2':
 511                         options.protocol = SSH_PROTO_2;
 512                         break;
 513                 case '4':
 514                         options.address_family = AF_INET;
 515                         break;
 516                 case '6':
 517                         options.address_family = AF_INET6;
 518                         break;
 519                 case 'n':
 520                         stdin_null_flag = 1;
 521                         break;
 522                 case 'f':
 523                         fork_after_authentication_flag = 1;
 524                         stdin_null_flag = 1;
 525                         break;
 526                 case 'x':
 527                         options.forward_x11 = 0;
 528                         break;
 529                 case 'X':
 530                         options.forward_x11 = 1;
 531                         break;
 532                 case 'y':
 533                         use_syslog = 1;
 534                         break;
 535                 case 'E':
 536                         logfile = xstrdup(optarg);
 537                         break;
 538                 case 'Y':
 539                         options.forward_x11 = 1;
 540                         options.forward_x11_trusted = 1;
 541                         break;
 542                 case 'g':
 543                         options.gateway_ports = 1;
 544                         break;
 545                 case 'O':
 546                         if (stdio_forward_host != NULL)
 547                                 fatal("Cannot specify multiplexing "
 548                                     "command with -W");
 549                         else if (muxclient_command != 0)
 550                                 fatal("Multiplexing command already specified");
 551                         if (strcmp(optarg, "check") == 0)
 552                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 553                         else if (strcmp(optarg, "forward") == 0)
 554                                 muxclient_command = SSHMUX_COMMAND_FORWARD;
 555                         else if (strcmp(optarg, "exit") == 0)
 556                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 557                         else if (strcmp(optarg, "stop") == 0)
 558                                 muxclient_command = SSHMUX_COMMAND_STOP;
 559                         else if (strcmp(optarg, "cancel") == 0)
 560                                 muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
 561                         else
 562                                 fatal("Invalid multiplex command.");
 563                         break;
 564                 case 'P':       /* deprecated */
 565                         options.use_privileged_port = 0;
 566                         break;
 567                 case 'Q':
 568                         cp = NULL;
 569                         if (strcmp(optarg, "cipher") == 0)
 570                                 cp = cipher_alg_list('\n', 0);
 571                         else if (strcmp(optarg, "cipher-auth") == 0)
 572                                 cp = cipher_alg_list('\n', 1);
 573                         else if (strcmp(optarg, "mac") == 0)
 574                                 cp = mac_alg_list('\n');
 575                         else if (strcmp(optarg, "kex") == 0)
 576                                 cp = kex_alg_list('\n');
 577                         else if (strcmp(optarg, "key") == 0)
 578                                 cp = key_alg_list(0, 0);
 579                         else if (strcmp(optarg, "key-cert") == 0)
 580                                 cp = key_alg_list(1, 0);
 581                         else if (strcmp(optarg, "key-plain") == 0)
 582                                 cp = key_alg_list(0, 1);
 583                         if (cp == NULL)
 584                                 fatal("Unsupported query \"%s\"", optarg);
 585                         printf("%s\n", cp);
 586                         free(cp);
 587                         exit(0);
 588                         break;
 589                 case 'a':
 590                         options.forward_agent = 0;
 591                         break;
 592                 case 'A':
 593                         options.forward_agent = 1;
 594                         break;
 595                 case 'k':
 596                         options.gss_deleg_creds = 0;
 597                         break;
 598                 case 'K':
 599                         options.gss_authentication = 1;
 600                         options.gss_deleg_creds = 1;
 601                         break;
 602                 case 'i':
 603                         if (stat(optarg, &st) < 0) {
 604                                 fprintf(stderr, "Warning: Identity file %s "
 605                                     "not accessible: %s.\n", optarg,
 606                                     strerror(errno));
 607                                 break;
 608                         }
 609                         add_identity_file(&options, NULL, optarg, 1);
 610                         break;
 611                 case 'I':
 612 #ifdef ENABLE_PKCS11
 613                         options.pkcs11_provider = xstrdup(optarg);
 614 #else
 615                         fprintf(stderr, "no support for PKCS#11.\n");
 616 #endif
 617                         break;
 618                 case 't':
 619                         if (options.request_tty == REQUEST_TTY_YES)
 620                                 options.request_tty = REQUEST_TTY_FORCE;
 621                         else
 622                                 options.request_tty = REQUEST_TTY_YES;
 623                         break;
 624                 case 'v':
 625                         if (debug_flag == 0) {
 626                                 debug_flag = 1;
 627                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 628                         } else {
 629                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 630                                         options.log_level++;
 631                         }
 632                         break;
 633                 case 'V':
 634                         if (options.version_addendum &&
 635                             *options.version_addendum != '\0')
 636                                 fprintf(stderr, "%s %s, %s\n", SSH_RELEASE,
 637                                     options.version_addendum,
 638                                     SSLeay_version(SSLEAY_VERSION));
 639                         else
 640                                 fprintf(stderr, "%s, %s\n", SSH_RELEASE,
 641                                     SSLeay_version(SSLEAY_VERSION));
 642                         if (opt == 'V')
 643                                 exit(0);
 644                         break;
 645                 case 'w':
 646                         if (options.tun_open == -1)
 647                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 648                         options.tun_local = a2tun(optarg, &options.tun_remote);
 649                         if (options.tun_local == SSH_TUNID_ERR) {
 650                                 fprintf(stderr,
 651                                     "Bad tun device '%s'\n", optarg);
 652                                 exit(255);
 653                         }
 654                         break;
 655                 case 'W':
 656                         if (stdio_forward_host != NULL)
 657                                 fatal("stdio forward already specified");
 658                         if (muxclient_command != 0)
 659                                 fatal("Cannot specify stdio forward with -O");
 660                         if (parse_forward(&fwd, optarg, 1, 0)) {
 661                                 stdio_forward_host = fwd.listen_host;
 662                                 stdio_forward_port = fwd.listen_port;
 663                                 free(fwd.connect_host);
 664                         } else {
 665                                 fprintf(stderr,
 666                                     "Bad stdio forwarding specification '%s'\n",
 667                                     optarg);
 668                                 exit(255);
 669                         }
 670                         options.request_tty = REQUEST_TTY_NO;
 671                         no_shell_flag = 1;
 672                         options.clear_forwardings = 1;
 673                         options.exit_on_forward_failure = 1;
 674                         break;
 675                 case 'q':
 676                         options.log_level = SYSLOG_LEVEL_QUIET;
 677                         break;
 678                 case 'e':
 679                         if (optarg[0] == '^' && optarg[2] == 0 &&
 680                             (u_char) optarg[1] >= 64 &&
 681                             (u_char) optarg[1] < 128)
 682                                 options.escape_char = (u_char) optarg[1] & 31;
 683                         else if (strlen(optarg) == 1)
 684                                 options.escape_char = (u_char) optarg[0];
 685                         else if (strcmp(optarg, "none") == 0)
 686                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 687                         else {
 688                                 fprintf(stderr, "Bad escape character '%s'.\n",
 689                                     optarg);
 690                                 exit(255);
 691                         }
 692                         break;
 693                 case 'c':
 694                         if (ciphers_valid(optarg)) {
 695                                 /* SSH2 only */
 696                                 options.ciphers = xstrdup(optarg);
 697                                 options.cipher = SSH_CIPHER_INVALID;
 698                         } else {
 699                                 /* SSH1 only */
 700                                 options.cipher = cipher_number(optarg);
 701                                 if (options.cipher == -1) {
 702                                         fprintf(stderr,
 703                                             "Unknown cipher type '%s'\n",
 704                                             optarg);
 705                                         exit(255);
 706                                 }
 707                                 if (options.cipher == SSH_CIPHER_3DES)
 708                                         options.ciphers = "3des-cbc";
 709                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 710                                         options.ciphers = "blowfish-cbc";
 711                                 else
 712                                         options.ciphers = (char *)-1;
 713                         }
 714                         break;
 715                 case 'm':
 716                         if (mac_valid(optarg))
 717                                 options.macs = xstrdup(optarg);
 718                         else {
 719                                 fprintf(stderr, "Unknown mac type '%s'\n",
 720                                     optarg);
 721                                 exit(255);
 722                         }
 723                         break;
 724                 case 'M':
 725                         if (options.control_master == SSHCTL_MASTER_YES)
 726                                 options.control_master = SSHCTL_MASTER_ASK;
 727                         else
 728                                 options.control_master = SSHCTL_MASTER_YES;
 729                         break;
 730                 case 'p':
 731                         options.port = a2port(optarg);
 732                         if (options.port <= 0) {
 733                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 734                                 exit(255);
 735                         }
 736                         break;
 737                 case 'l':
 738                         options.user = optarg;
 739                         break;
 740
 741                 case 'L':
 742                         if (parse_forward(&fwd, optarg, 0, 0))
 743                                 add_local_forward(&options, &fwd);
 744                         else {
 745                                 fprintf(stderr,
 746                                     "Bad local forwarding specification '%s'\n",
 747                                     optarg);
 748                                 exit(255);
 749                         }
 750                         break;
 751
 752                 case 'R':
 753                         if (parse_forward(&fwd, optarg, 0, 1)) {
 754                                 add_remote_forward(&options, &fwd);
 755                         } else {
 756                                 fprintf(stderr,
 757                                     "Bad remote forwarding specification "
 758                                     "'%s'\n", optarg);
 759                                 exit(255);
 760                         }
 761                         break;
 762
 763                 case 'D':
 764                         if (parse_forward(&fwd, optarg, 1, 0)) {
 765                                 add_local_forward(&options, &fwd);
 766                         } else {
 767                                 fprintf(stderr,
 768                                     "Bad dynamic forwarding specification "
 769                                     "'%s'\n", optarg);
 770                                 exit(255);
 771                         }
 772                         break;
 773
 774                 case 'C':
 775                         options.compression = 1;
 776                         break;
 777                 case 'N':
 778                         no_shell_flag = 1;
 779                         options.request_tty = REQUEST_TTY_NO;
 780                         break;
 781                 case 'T':
 782                         options.request_tty = REQUEST_TTY_NO;
 783                         break;
 784                 case 'o':
 785                         line = xstrdup(optarg);
 786                         if (process_config_line(&options, pw, host ? host : "",
 787                             line, "command-line", 0, NULL, SSHCONF_USERCONF)
 788                             != 0)
 789                                 exit(255);
 790                         free(line);
 791                         break;
 792                 case 's':
 793                         subsystem_flag = 1;
 794                         break;
 795                 case 'S':
 796                         if (options.control_path != NULL)
 797                                 free(options.control_path);
 798                         options.control_path = xstrdup(optarg);
 799                         break;
 800                 case 'b':
 801                         options.bind_address = optarg;
 802                         break;
 803                 case 'F':
 804                         config = optarg;
 805                         break;
 806                 default:
 807                         usage();
 808                 }
 809         }
 810
 811         ac -= optind;
 812         av += optind;
 813
 814         if (ac > 0 && !host) {
 815                 if (strrchr(*av, '@')) {
 816                         p = xstrdup(*av);
 817                         cp = strrchr(p, '@');
 818                         if (cp == NULL || cp == p)
 819                                 usage();
 820                         options.user = p;
 821                         *cp = '\0';
 822                         host = xstrdup(++cp);
 823                 } else
 824                         host = xstrdup(*av);
 825                 if (ac > 1) {
 826                         optind = optreset = 1;
 827                         goto again;
 828                 }
 829                 ac--, av++;
 830         }
 831
 832         /* Check that we got a host name. */
 833         if (!host)
 834                 usage();
 835
 836         host_arg = xstrdup(host);
 837
 838         OpenSSL_add_all_algorithms();
 839         ERR_load_crypto_strings();
 840
 841         /* Initialize the command to execute on remote host. */
 842         buffer_init(&command);
 843
 844         /*
 845          * Save the command to execute on the remote host in a buffer. There
 846          * is no limit on the length of the command, except by the maximum
 847          * packet size.  Also sets the tty flag if there is no command.
 848          */
 849         if (!ac) {
 850                 /* No command specified - execute shell on a tty. */
 851                 if (subsystem_flag) {
 852                         fprintf(stderr,
 853                             "You must specify a subsystem to invoke.\n");
 854                         usage();
 855                 }
 856         } else {
 857                 /* A command has been specified.  Store it into the buffer. */
 858                 for (i = 0; i < ac; i++) {
 859                         if (i)
 860                                 buffer_append(&command, " ", 1);
 861                         buffer_append(&command, av[i], strlen(av[i]));
 862                 }
 863         }
 864
 865         /* Cannot fork to background if no command. */
 866         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 867             !no_shell_flag)
 868                 fatal("Cannot fork into background without a command "
 869                     "to execute.");
 870
 871         /*
 872          * Initialize "log" output.  Since we are the client all output
 873          * goes to stderr unless otherwise specified by -y or -E.
 874          */
 875         if (use_syslog && logfile != NULL)
 876                 fatal("Can't specify both -y and -E");
 877         if (logfile != NULL) {
 878                 log_redirect_stderr_to(logfile);
 879                 free(logfile);
 880         }
 881         log_init(argv0,
 882             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 883             SYSLOG_FACILITY_USER, !use_syslog);
 884
 885         if (debug_flag)
 886                 logit("%s, %s", SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 887
 888         /* Parse the configuration files */
 889         process_config_files(pw);
 890
 891         /* Hostname canonicalisation needs a few options filled. */
 892         fill_default_options_for_canonicalization(&options);
 893
 894         /* If the user has replaced the hostname then take it into use now */
 895         if (options.hostname != NULL) {
 896                 /* NB. Please keep in sync with readconf.c:match_cfg_line() */
 897                 cp = percent_expand(options.hostname,
 898                     "h", host, (char *)NULL);
 899                 free(host);
 900                 host = cp;
 901         }
 902
 903         /* If canonicalization requested then try to apply it */
 904         lowercase(host);
 905         if (options.canonicalize_hostname != SSH_CANONICALISE_NO)
 906                 addrs = resolve_canonicalize(&host, options.port);
 907
 908         /*
 909          * If CanonicalizePermittedCNAMEs have been specified but
 910          * other canonicalization did not happen (by not being requested
 911          * or by failing with fallback) then the hostname may still be changed
 912          * as a result of CNAME following.
 913          *
 914          * Try to resolve the bare hostname name using the system resolver's
 915          * usual search rules and then apply the CNAME follow rules.
 916          *
 917          * Skip the lookup if a ProxyCommand is being used unless the user
 918          * has specifically requested canonicalisation for this case via
 919          * CanonicalizeHostname=always
 920          */
 921         if (addrs == NULL && options.num_permitted_cnames != 0 &&
 922             (option_clear_or_none(options.proxy_command) ||
 923             options.canonicalize_hostname == SSH_CANONICALISE_ALWAYS)) {
 924                 if ((addrs = resolve_host(host, options.port, 1,
 925                     cname, sizeof(cname))) == NULL)
 926                         cleanup_exit(255); /* resolve_host logs the error */
 927                 check_follow_cname(&host, cname);
 928         }
 929
 930         /*
 931          * If the target hostname has changed as a result of canonicalisation
 932          * then re-parse the configuration files as new stanzas may match.
 933          */
 934         if (strcasecmp(host_arg, host) != 0) {
 935                 debug("Hostname has changed; re-reading configuration");
 936                 process_config_files(pw);
 937         }
 938
 939         /* Fill configuration defaults. */
 940         fill_default_options(&options);
 941
 942         if (options.port == 0)
 943                 options.port = default_ssh_port();
 944         channel_set_af(options.address_family);
 945
 946         /* Tidy and check options */
 947         if (options.host_key_alias != NULL)
 948                 lowercase(options.host_key_alias);
 949         if (options.proxy_command != NULL &&
 950             strcmp(options.proxy_command, "-") == 0 &&
 951             options.proxy_use_fdpass)
 952                 fatal("ProxyCommand=- and ProxyUseFDPass are incompatible");
 953 #ifndef HAVE_CYGWIN
 954         if (original_effective_uid != 0)
 955                 options.use_privileged_port = 0;
 956 #endif
 957
 958         /* reinit */
 959         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 960
 961         if (options.request_tty == REQUEST_TTY_YES ||
 962             options.request_tty == REQUEST_TTY_FORCE)
 963                 tty_flag = 1;
 964
 965         /* Allocate a tty by default if no command specified. */
 966         if (buffer_len(&command) == 0)
 967                 tty_flag = options.request_tty != REQUEST_TTY_NO;
 968
 969         /* Force no tty */
 970         if (options.request_tty == REQUEST_TTY_NO || muxclient_command != 0)
 971                 tty_flag = 0;
 972         /* Do not allocate a tty if stdin is not a tty. */
 973         if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
 974             options.request_tty != REQUEST_TTY_FORCE) {
 975                 if (tty_flag)
 976                         logit("Pseudo-terminal will not be allocated because "
 977                             "stdin is not a terminal.");
 978                 tty_flag = 0;
 979         }
 980
 981         seed_rng();
 982
 983         if (options.user == NULL)
 984                 options.user = xstrdup(pw->pw_name);
 985
 986         if (gethostname(thishost, sizeof(thishost)) == -1)
 987                 fatal("gethostname: %s", strerror(errno));
 988         strlcpy(shorthost, thishost, sizeof(shorthost));
 989         shorthost[strcspn(thishost, ".")] = '\0';
 990         snprintf(portstr, sizeof(portstr), "%d", options.port);
 991
 992         /* Find canonic host name. */
 993         if (strchr(host, '.') == 0) {
 994                 struct addrinfo hints;
 995                 struct addrinfo *ai = NULL;
 996                 int errgai;
 997                 memset(&hints, 0, sizeof(hints));
 998                 hints.ai_family = options.address_family;
 999                 hints.ai_flags = AI_CANONNAME;
1000                 hints.ai_socktype = SOCK_STREAM;
1001                 errgai = getaddrinfo(host, NULL, &hints, &ai);
1002                 if (errgai == 0) {
1003                         if (ai->ai_canonname != NULL)
1004                                 host = xstrdup(ai->ai_canonname);
1005                         freeaddrinfo(ai);
1006                 }
1007         }
1008
1009         if (options.local_command != NULL) {
1010                 debug3("expanding LocalCommand: %s", options.local_command);
1011                 cp = options.local_command;
1012                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
1013                     "h", host, "l", thishost, "n", host_arg, "r", options.user,
1014                     "p", portstr, "u", pw->pw_name, "L", shorthost,
1015                     (char *)NULL);
1016                 debug3("expanded LocalCommand: %s", options.local_command);
1017                 free(cp);
1018         }
1019
1020         if (options.control_path != NULL) {
1021                 cp = tilde_expand_filename(options.control_path,
1022                     original_real_uid);
1023                 free(options.control_path);
1024                 options.control_path = percent_expand(cp, "h", host,
1025                     "l", thishost, "n", host_arg, "r", options.user,
1026                     "p", portstr, "u", pw->pw_name, "L", shorthost,
1027                     (char *)NULL);
1028                 free(cp);
1029         }
1030         if (muxclient_command != 0 && options.control_path == NULL)
1031                 fatal("No ControlPath specified for \"-O\" command");
1032         if (options.control_path != NULL)
1033                 muxclient(options.control_path);
1034
1035         /*
1036          * If hostname canonicalisation was not enabled, then we may not
1037          * have yet resolved the hostname. Do so now.
1038          */
1039         if (addrs == NULL && options.proxy_command == NULL) {
1040                 if ((addrs = resolve_host(host, options.port, 1,
1041                     cname, sizeof(cname))) == NULL)
1042                         cleanup_exit(255); /* resolve_host logs the error */
1043         }
1044
1045         timeout_ms = options.connection_timeout * 1000;
1046
1047         /* Open a connection to the remote host. */
1048         if (ssh_connect(host, addrs, &hostaddr, options.port,
1049             options.address_family, options.connection_attempts,
1050             &timeout_ms, options.tcp_keep_alive,
1051             options.use_privileged_port) != 0)
1052                 exit(255);
1053
1054         if (addrs != NULL)
1055                 freeaddrinfo(addrs);
1056
1057         packet_set_timeout(options.server_alive_interval,
1058             options.server_alive_count_max);
1059
1060         if (timeout_ms > 0)
1061                 debug3("timeout: %d ms remain after connect", timeout_ms);
1062
1063         /*
1064          * If we successfully made the connection, load the host private key
1065          * in case we will need it later for combined rsa-rhosts
1066          * authentication. This must be done before releasing extra
1067          * privileges, because the file is only readable by root.
1068          * If we cannot access the private keys, load the public keys
1069          * instead and try to execute the ssh-keysign helper instead.
1070          */
1071         sensitive_data.nkeys = 0;
1072         sensitive_data.keys = NULL;
1073         sensitive_data.external_keysign = 0;
1074         if (options.rhosts_rsa_authentication ||
1075             options.hostbased_authentication) {
1076                 sensitive_data.nkeys = 9;
1077                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
1078                     sizeof(Key));
1079                 for (i = 0; i < sensitive_data.nkeys; i++)
1080                         sensitive_data.keys[i] = NULL;
1081
1082                 PRIV_START;
1083                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
1084                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
1085                 sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
1086                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
1087 #ifdef OPENSSL_HAS_ECC
1088                 sensitive_data.keys[2] = key_load_private_cert(KEY_ECDSA,
1089                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
1090 #endif
1091                 sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
1092                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
1093                 sensitive_data.keys[4] = key_load_private_cert(KEY_ED25519,
1094                     _PATH_HOST_ED25519_KEY_FILE, "", NULL);
1095                 sensitive_data.keys[5] = key_load_private_type(KEY_DSA,
1096                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
1097 #ifdef OPENSSL_HAS_ECC
1098                 sensitive_data.keys[6] = key_load_private_type(KEY_ECDSA,
1099                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
1100 #endif
1101                 sensitive_data.keys[7] = key_load_private_type(KEY_RSA,
1102                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
1103                 sensitive_data.keys[8] = key_load_private_type(KEY_ED25519,
1104                     _PATH_HOST_ED25519_KEY_FILE, "", NULL, NULL);
1105                 PRIV_END;
1106
1107                 if (options.hostbased_authentication == 1 &&
1108                     sensitive_data.keys[0] == NULL &&
1109                     sensitive_data.keys[5] == NULL &&
1110                     sensitive_data.keys[6] == NULL &&
1111                     sensitive_data.keys[7] == NULL &&
1112                     sensitive_data.keys[8] == NULL) {
1113                         sensitive_data.keys[1] = key_load_cert(
1114                             _PATH_HOST_DSA_KEY_FILE);
1115 #ifdef OPENSSL_HAS_ECC
1116                         sensitive_data.keys[2] = key_load_cert(
1117                             _PATH_HOST_ECDSA_KEY_FILE);
1118 #endif
1119                         sensitive_data.keys[3] = key_load_cert(
1120                             _PATH_HOST_RSA_KEY_FILE);
1121                         sensitive_data.keys[4] = key_load_cert(
1122                             _PATH_HOST_ED25519_KEY_FILE);
1123                         sensitive_data.keys[5] = key_load_public(
1124                             _PATH_HOST_DSA_KEY_FILE, NULL);
1125 #ifdef OPENSSL_HAS_ECC
1126                         sensitive_data.keys[6] = key_load_public(
1127                             _PATH_HOST_ECDSA_KEY_FILE, NULL);
1128 #endif
1129                         sensitive_data.keys[7] = key_load_public(
1130                             _PATH_HOST_RSA_KEY_FILE, NULL);
1131                         sensitive_data.keys[8] = key_load_public(
1132                             _PATH_HOST_ED25519_KEY_FILE, NULL);
1133                         sensitive_data.external_keysign = 1;
1134                 }
1135         }
1136         /*
1137          * Get rid of any extra privileges that we may have.  We will no
1138          * longer need them.  Also, extra privileges could make it very hard
1139          * to read identity files and other non-world-readable files from the
1140          * user's home directory if it happens to be on a NFS volume where
1141          * root is mapped to nobody.
1142          */
1143         if (original_effective_uid == 0) {
1144                 PRIV_START;
1145                 permanently_set_uid(pw);
1146         }
1147
1148         /*
1149          * Now that we are back to our own permissions, create ~/.ssh
1150          * directory if it doesn't already exist.
1151          */
1152         if (config == NULL) {
1153                 r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
1154                     strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
1155                 if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
1156 #ifdef WITH_SELINUX
1157                         ssh_selinux_setfscreatecon(buf);
1158 #endif
1159                         if (mkdir(buf, 0700) < 0)
1160                                 error("Could not create directory '%.200s'.",
1161                                     buf);
1162 #ifdef WITH_SELINUX
1163                         ssh_selinux_setfscreatecon(NULL);
1164 #endif
1165                 }
1166         }
1167         /* load options.identity_files */
1168         load_public_identity_files();
1169
1170         /* Expand ~ in known host file names. */
1171         tilde_expand_paths(options.system_hostfiles,
1172             options.num_system_hostfiles);
1173         tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
1174
1175         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
1176         signal(SIGCHLD, main_sigchld_handler);
1177
1178         /* Log into the remote system.  Never returns if the login fails. */
1179         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
1180             options.port, pw, timeout_ms);
1181
1182         if (packet_connection_is_on_socket()) {
1183                 verbose("Authenticated to %s ([%s]:%d).", host,
1184                     get_remote_ipaddr(), get_remote_port());
1185         } else {
1186                 verbose("Authenticated to %s (via proxy).", host);
1187         }
1188
1189         /* We no longer need the private host keys.  Clear them now. */
1190         if (sensitive_data.nkeys != 0) {
1191                 for (i = 0; i < sensitive_data.nkeys; i++) {
1192                         if (sensitive_data.keys[i] != NULL) {
1193                                 /* Destroys contents safely */
1194                                 debug3("clear hostkey %d", i);
1195                                 key_free(sensitive_data.keys[i]);
1196                                 sensitive_data.keys[i] = NULL;
1197                         }
1198                 }
1199                 free(sensitive_data.keys);
1200         }
1201         for (i = 0; i < options.num_identity_files; i++) {
1202                 free(options.identity_files[i]);
1203                 options.identity_files[i] = NULL;
1204                 if (options.identity_keys[i]) {
1205                         key_free(options.identity_keys[i]);
1206                         options.identity_keys[i] = NULL;
1207                 }
1208         }
1209
1210         exit_status = compat20 ? ssh_session2() : ssh_session();
1211         packet_close();
1212
1213         if (options.control_path != NULL && muxserver_sock != -1)
1214                 unlink(options.control_path);
1215
1216         /* Kill ProxyCommand if it is running. */
1217         ssh_kill_proxy_command();
1218
1219         return exit_status;
1220 }
1221
1222 static void
1223 control_persist_detach(void)
1224 {
1225         pid_t pid;
1226         int devnull;
1227
1228         debug("%s: backgrounding master process", __func__);
1229
1230         /*
1231          * master (current process) into the background, and make the
1232          * foreground process a client of the backgrounded master.
1233          */
1234         switch ((pid = fork())) {
1235         case -1:
1236                 fatal("%s: fork: %s", __func__, strerror(errno));
1237         case 0:
1238                 /* Child: master process continues mainloop */
1239                 break;
1240         default:
1241                 /* Parent: set up mux slave to connect to backgrounded master */
1242                 debug2("%s: background process is %ld", __func__, (long)pid);
1243                 stdin_null_flag = ostdin_null_flag;
1244                 options.request_tty = orequest_tty;
1245                 tty_flag = otty_flag;
1246                 close(muxserver_sock);
1247                 muxserver_sock = -1;
1248                 options.control_master = SSHCTL_MASTER_NO;
1249                 muxclient(options.control_path);
1250                 /* muxclient() doesn't return on success. */
1251                 fatal("Failed to connect to new control master");
1252         }
1253         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1254                 error("%s: open(\"/dev/null\"): %s", __func__,
1255                     strerror(errno));
1256         } else {
1257                 if (dup2(devnull, STDIN_FILENO) == -1 ||
1258                     dup2(devnull, STDOUT_FILENO) == -1)
1259                         error("%s: dup2: %s", __func__, strerror(errno));
1260                 if (devnull > STDERR_FILENO)
1261                         close(devnull);
1262         }
1263         daemon(1, 1);
1264         setproctitle("%s [mux]", options.control_path);
1265 }
1266
1267 /* Do fork() after authentication. Used by "ssh -f" */
1268 static void
1269 fork_postauth(void)
1270 {
1271         if (need_controlpersist_detach)
1272                 control_persist_detach();
1273         debug("forking to background");
1274         fork_after_authentication_flag = 0;
1275         if (daemon(1, 1) < 0)
1276                 fatal("daemon() failed: %.200s", strerror(errno));
1277 }
1278
1279 /* Callback for remote forward global requests */
1280 static void
1281 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
1282 {
1283         Forward *rfwd = (Forward *)ctxt;
1284
1285         /* XXX verbose() on failure? */
1286         debug("remote forward %s for: listen %d, connect %s:%d",
1287             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1288             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
1289         if (rfwd->listen_port == 0) {
1290                 if (type == SSH2_MSG_REQUEST_SUCCESS) {
1291                         rfwd->allocated_port = packet_get_int();
1292                         logit("Allocated port %u for remote forward to %s:%d",
1293                             rfwd->allocated_port,
1294                             rfwd->connect_host, rfwd->connect_port);
1295                         channel_update_permitted_opens(rfwd->handle,
1296                             rfwd->allocated_port);
1297                 } else {
1298                         channel_update_permitted_opens(rfwd->handle, -1);
1299                 }
1300         }
1301
1302         if (type == SSH2_MSG_REQUEST_FAILURE) {
1303                 if (options.exit_on_forward_failure)
1304                         fatal("Error: remote port forwarding failed for "
1305                             "listen port %d", rfwd->listen_port);
1306                 else
1307                         logit("Warning: remote port forwarding failed for "
1308                             "listen port %d", rfwd->listen_port);
1309         }
1310         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1311                 debug("All remote forwarding requests processed");
1312                 if (fork_after_authentication_flag)
1313                         fork_postauth();
1314         }
1315 }
1316
1317 static void
1318 client_cleanup_stdio_fwd(int id, void *arg)
1319 {
1320         debug("stdio forwarding: done");
1321         cleanup_exit(0);
1322 }
1323
1324 static void
1325 ssh_init_stdio_forwarding(void)
1326 {
1327         Channel *c;
1328         int in, out;
1329
1330         if (stdio_forward_host == NULL)
1331                 return;
1332         if (!compat20)
1333                 fatal("stdio forwarding require Protocol 2");
1334
1335         debug3("%s: %s:%d", __func__, stdio_forward_host, stdio_forward_port);
1336
1337         if ((in = dup(STDIN_FILENO)) < 0 ||
1338             (out = dup(STDOUT_FILENO)) < 0)
1339                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1340         if ((c = channel_connect_stdio_fwd(stdio_forward_host,
1341             stdio_forward_port, in, out)) == NULL)
1342                 fatal("%s: channel_connect_stdio_fwd failed", __func__);
1343         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1344 }
1345
1346 static void
1347 ssh_init_forwarding(void)
1348 {
1349         int success = 0;
1350         int i;
1351
1352         /* Initiate local TCP/IP port forwardings. */
1353         for (i = 0; i < options.num_local_forwards; i++) {
1354                 debug("Local connections to %.200s:%d forwarded to remote "
1355                     "address %.200s:%d",
1356                     (options.local_forwards[i].listen_host == NULL) ?
1357                     (options.gateway_ports ? "*" : "LOCALHOST") :
1358                     options.local_forwards[i].listen_host,
1359                     options.local_forwards[i].listen_port,
1360                     options.local_forwards[i].connect_host,
1361                     options.local_forwards[i].connect_port);
1362                 success += channel_setup_local_fwd_listener(
1363                     options.local_forwards[i].listen_host,
1364                     options.local_forwards[i].listen_port,
1365                     options.local_forwards[i].connect_host,
1366                     options.local_forwards[i].connect_port,
1367                     options.gateway_ports);
1368         }
1369         if (i > 0 && success != i && options.exit_on_forward_failure)
1370                 fatal("Could not request local forwarding.");
1371         if (i > 0 && success == 0)
1372                 error("Could not request local forwarding.");
1373
1374         /* Initiate remote TCP/IP port forwardings. */
1375         for (i = 0; i < options.num_remote_forwards; i++) {
1376                 debug("Remote connections from %.200s:%d forwarded to "
1377                     "local address %.200s:%d",
1378                     (options.remote_forwards[i].listen_host == NULL) ?
1379                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1380                     options.remote_forwards[i].listen_port,
1381                     options.remote_forwards[i].connect_host,
1382                     options.remote_forwards[i].connect_port);
1383                 options.remote_forwards[i].handle =
1384                     channel_request_remote_forwarding(
1385                     options.remote_forwards[i].listen_host,
1386                     options.remote_forwards[i].listen_port,
1387                     options.remote_forwards[i].connect_host,
1388                     options.remote_forwards[i].connect_port);
1389                 if (options.remote_forwards[i].handle < 0) {
1390                         if (options.exit_on_forward_failure)
1391                                 fatal("Could not request remote forwarding.");
1392                         else
1393                                 logit("Warning: Could not request remote "
1394                                     "forwarding.");
1395                 } else {
1396                         client_register_global_confirm(ssh_confirm_remote_forward,
1397                             &options.remote_forwards[i]);
1398                 }
1399         }
1400
1401         /* Initiate tunnel forwarding. */
1402         if (options.tun_open != SSH_TUNMODE_NO) {
1403                 if (client_request_tun_fwd(options.tun_open,
1404                     options.tun_local, options.tun_remote) == -1) {
1405                         if (options.exit_on_forward_failure)
1406                                 fatal("Could not request tunnel forwarding.");
1407                         else
1408                                 error("Could not request tunnel forwarding.");
1409                 }
1410         }
1411 }
1412
1413 static void
1414 check_agent_present(void)
1415 {
1416         if (options.forward_agent) {
1417                 /* Clear agent forwarding if we don't have an agent. */
1418                 if (!ssh_agent_present())
1419                         options.forward_agent = 0;
1420         }
1421 }
1422
1423 static int
1424 ssh_session(void)
1425 {
1426         int type;
1427         int interactive = 0;
1428         int have_tty = 0;
1429         struct winsize ws;
1430         char *cp;
1431         const char *display;
1432
1433         /* Enable compression if requested. */
1434         if (options.compression) {
1435                 debug("Requesting compression at level %d.",
1436                     options.compression_level);
1437
1438                 if (options.compression_level < 1 ||
1439                     options.compression_level > 9)
1440                         fatal("Compression level must be from 1 (fast) to "
1441                             "9 (slow, best).");
1442
1443                 /* Send the request. */
1444                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1445                 packet_put_int(options.compression_level);
1446                 packet_send();
1447                 packet_write_wait();
1448                 type = packet_read();
1449                 if (type == SSH_SMSG_SUCCESS)
1450                         packet_start_compression(options.compression_level);
1451                 else if (type == SSH_SMSG_FAILURE)
1452                         logit("Warning: Remote host refused compression.");
1453                 else
1454                         packet_disconnect("Protocol error waiting for "
1455                             "compression response.");
1456         }
1457         /* Allocate a pseudo tty if appropriate. */
1458         if (tty_flag) {
1459                 debug("Requesting pty.");
1460
1461                 /* Start the packet. */
1462                 packet_start(SSH_CMSG_REQUEST_PTY);
1463
1464                 /* Store TERM in the packet.  There is no limit on the
1465                    length of the string. */
1466                 cp = getenv("TERM");
1467                 if (!cp)
1468                         cp = "";
1469                 packet_put_cstring(cp);
1470
1471                 /* Store window size in the packet. */
1472                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1473                         memset(&ws, 0, sizeof(ws));
1474                 packet_put_int((u_int)ws.ws_row);
1475                 packet_put_int((u_int)ws.ws_col);
1476                 packet_put_int((u_int)ws.ws_xpixel);
1477                 packet_put_int((u_int)ws.ws_ypixel);
1478
1479                 /* Store tty modes in the packet. */
1480                 tty_make_modes(fileno(stdin), NULL);
1481
1482                 /* Send the packet, and wait for it to leave. */
1483                 packet_send();
1484                 packet_write_wait();
1485
1486                 /* Read response from the server. */
1487                 type = packet_read();
1488                 if (type == SSH_SMSG_SUCCESS) {
1489                         interactive = 1;
1490                         have_tty = 1;
1491                 } else if (type == SSH_SMSG_FAILURE)
1492                         logit("Warning: Remote host failed or refused to "
1493                             "allocate a pseudo tty.");
1494                 else
1495                         packet_disconnect("Protocol error waiting for pty "
1496                             "request response.");
1497         }
1498         /* Request X11 forwarding if enabled and DISPLAY is set. */
1499         display = getenv("DISPLAY");
1500         if (options.forward_x11 && display != NULL) {
1501                 char *proto, *data;
1502                 /* Get reasonable local authentication information. */
1503                 client_x11_get_proto(display, options.xauth_location,
1504                     options.forward_x11_trusted,
1505                     options.forward_x11_timeout,
1506                     &proto, &data);
1507                 /* Request forwarding with authentication spoofing. */
1508                 debug("Requesting X11 forwarding with authentication "
1509                     "spoofing.");
1510                 x11_request_forwarding_with_spoofing(0, display, proto,
1511                     data, 0);
1512                 /* Read response from the server. */
1513                 type = packet_read();
1514                 if (type == SSH_SMSG_SUCCESS) {
1515                         interactive = 1;
1516                 } else if (type == SSH_SMSG_FAILURE) {
1517                         logit("Warning: Remote host denied X11 forwarding.");
1518                 } else {
1519                         packet_disconnect("Protocol error waiting for X11 "
1520                             "forwarding");
1521                 }
1522         }
1523         /* Tell the packet module whether this is an interactive session. */
1524         packet_set_interactive(interactive,
1525             options.ip_qos_interactive, options.ip_qos_bulk);
1526
1527         /* Request authentication agent forwarding if appropriate. */
1528         check_agent_present();
1529
1530         if (options.forward_agent) {
1531                 debug("Requesting authentication agent forwarding.");
1532                 auth_request_forwarding();
1533
1534                 /* Read response from the server. */
1535                 type = packet_read();
1536                 packet_check_eom();
1537                 if (type != SSH_SMSG_SUCCESS)
1538                         logit("Warning: Remote host denied authentication agent forwarding.");
1539         }
1540
1541         /* Initiate port forwardings. */
1542         ssh_init_stdio_forwarding();
1543         ssh_init_forwarding();
1544
1545         /* Execute a local command */
1546         if (options.local_command != NULL &&
1547             options.permit_local_command)
1548                 ssh_local_cmd(options.local_command);
1549
1550         /*
1551          * If requested and we are not interested in replies to remote
1552          * forwarding requests, then let ssh continue in the background.
1553          */
1554         if (fork_after_authentication_flag) {
1555                 if (options.exit_on_forward_failure &&
1556                     options.num_remote_forwards > 0) {
1557                         debug("deferring postauth fork until remote forward "
1558                             "confirmation received");
1559                 } else
1560                         fork_postauth();
1561         }
1562
1563         /*
1564          * If a command was specified on the command line, execute the
1565          * command now. Otherwise request the server to start a shell.
1566          */
1567         if (buffer_len(&command) > 0) {
1568                 int len = buffer_len(&command);
1569                 if (len > 900)
1570                         len = 900;
1571                 debug("Sending command: %.*s", len,
1572                     (u_char *)buffer_ptr(&command));
1573                 packet_start(SSH_CMSG_EXEC_CMD);
1574                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1575                 packet_send();
1576                 packet_write_wait();
1577         } else {
1578                 debug("Requesting shell.");
1579                 packet_start(SSH_CMSG_EXEC_SHELL);
1580                 packet_send();
1581                 packet_write_wait();
1582         }
1583
1584         /* Enter the interactive session. */
1585         return client_loop(have_tty, tty_flag ?
1586             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1587 }
1588
1589 /* request pty/x11/agent/tcpfwd/shell for channel */
1590 static void
1591 ssh_session2_setup(int id, int success, void *arg)
1592 {
1593         extern char **environ;
1594         const char *display;
1595         int interactive = tty_flag;
1596
1597         if (!success)
1598                 return; /* No need for error message, channels code sens one */
1599
1600         display = getenv("DISPLAY");
1601         if (options.forward_x11 && display != NULL) {
1602                 char *proto, *data;
1603                 /* Get reasonable local authentication information. */
1604                 client_x11_get_proto(display, options.xauth_location,
1605                     options.forward_x11_trusted,
1606                     options.forward_x11_timeout, &proto, &data);
1607                 /* Request forwarding with authentication spoofing. */
1608                 debug("Requesting X11 forwarding with authentication "
1609                     "spoofing.");
1610                 x11_request_forwarding_with_spoofing(id, display, proto,
1611                     data, 1);
1612                 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
1613                 /* XXX exit_on_forward_failure */
1614                 interactive = 1;
1615         }
1616
1617         check_agent_present();
1618         if (options.forward_agent) {
1619                 debug("Requesting authentication agent forwarding.");
1620                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1621                 packet_send();
1622         }
1623
1624         /* Tell the packet module whether this is an interactive session. */
1625         packet_set_interactive(interactive,
1626             options.ip_qos_interactive, options.ip_qos_bulk);
1627
1628         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1629             NULL, fileno(stdin), &command, environ);
1630 }
1631
1632 /* open new channel for a session */
1633 static int
1634 ssh_session2_open(void)
1635 {
1636         Channel *c;
1637         int window, packetmax, in, out, err;
1638
1639         if (stdin_null_flag) {
1640                 in = open(_PATH_DEVNULL, O_RDONLY);
1641         } else {
1642                 in = dup(STDIN_FILENO);
1643         }
1644         out = dup(STDOUT_FILENO);
1645         err = dup(STDERR_FILENO);
1646
1647         if (in < 0 || out < 0 || err < 0)
1648                 fatal("dup() in/out/err failed");
1649
1650         /* enable nonblocking unless tty */
1651         if (!isatty(in))
1652                 set_nonblock(in);
1653         if (!isatty(out))
1654                 set_nonblock(out);
1655         if (!isatty(err))
1656                 set_nonblock(err);
1657
1658         window = CHAN_SES_WINDOW_DEFAULT;
1659         packetmax = CHAN_SES_PACKET_DEFAULT;
1660         if (tty_flag) {
1661                 window >>= 1;
1662                 packetmax >>= 1;
1663         }
1664         c = channel_new(
1665             "session", SSH_CHANNEL_OPENING, in, out, err,
1666             window, packetmax, CHAN_EXTENDED_WRITE,
1667             "client-session", /*nonblock*/0);
1668
1669         debug3("ssh_session2_open: channel_new: %d", c->self);
1670
1671         channel_send_open(c->self);
1672         if (!no_shell_flag)
1673                 channel_register_open_confirm(c->self,
1674                     ssh_session2_setup, NULL);
1675
1676         return c->self;
1677 }
1678
1679 static int
1680 ssh_session2(void)
1681 {
1682         int id = -1;
1683
1684         /* XXX should be pre-session */
1685         if (!options.control_persist)
1686                 ssh_init_stdio_forwarding();
1687         ssh_init_forwarding();
1688
1689         /* Start listening for multiplex clients */
1690         muxserver_listen();
1691
1692         /*
1693          * If we are in control persist mode and have a working mux listen
1694          * socket, then prepare to background ourselves and have a foreground
1695          * client attach as a control slave.
1696          * NB. we must save copies of the flags that we override for
1697          * the backgrounding, since we defer attachment of the slave until
1698          * after the connection is fully established (in particular,
1699          * async rfwd replies have been received for ExitOnForwardFailure).
1700          */
1701         if (options.control_persist && muxserver_sock != -1) {
1702                 ostdin_null_flag = stdin_null_flag;
1703                 ono_shell_flag = no_shell_flag;
1704                 orequest_tty = options.request_tty;
1705                 otty_flag = tty_flag;
1706                 stdin_null_flag = 1;
1707                 no_shell_flag = 1;
1708                 tty_flag = 0;
1709                 if (!fork_after_authentication_flag)
1710                         need_controlpersist_detach = 1;
1711                 fork_after_authentication_flag = 1;
1712         }
1713         /*
1714          * ControlPersist mux listen socket setup failed, attempt the
1715          * stdio forward setup that we skipped earlier.
1716          */
1717         if (options.control_persist && muxserver_sock == -1)
1718                 ssh_init_stdio_forwarding();
1719
1720         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1721                 id = ssh_session2_open();
1722         else {
1723                 packet_set_interactive(
1724                     options.control_master == SSHCTL_MASTER_NO,
1725                     options.ip_qos_interactive, options.ip_qos_bulk);
1726         }
1727
1728         /* If we don't expect to open a new session, then disallow it */
1729         if (options.control_master == SSHCTL_MASTER_NO &&
1730             (datafellows & SSH_NEW_OPENSSH)) {
1731                 debug("Requesting no-more-sessions@openssh.com");
1732                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1733                 packet_put_cstring("no-more-sessions@openssh.com");
1734                 packet_put_char(0);
1735                 packet_send();
1736         }
1737
1738         /* Execute a local command */
1739         if (options.local_command != NULL &&
1740             options.permit_local_command)
1741                 ssh_local_cmd(options.local_command);
1742
1743         /*
1744          * If requested and we are not interested in replies to remote
1745          * forwarding requests, then let ssh continue in the background.
1746          */
1747         if (fork_after_authentication_flag) {
1748                 if (options.exit_on_forward_failure &&
1749                     options.num_remote_forwards > 0) {
1750                         debug("deferring postauth fork until remote forward "
1751                             "confirmation received");
1752                 } else
1753                         fork_postauth();
1754         }
1755
1756         if (options.use_roaming)
1757                 request_roaming();
1758
1759         return client_loop(tty_flag, tty_flag ?
1760             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1761 }
1762
1763 static void
1764 load_public_identity_files(void)
1765 {
1766         char *filename, *cp, thishost[NI_MAXHOST];
1767         char *pwdir = NULL, *pwname = NULL;
1768         int i = 0;
1769         Key *public;
1770         struct passwd *pw;
1771         u_int n_ids;
1772         char *identity_files[SSH_MAX_IDENTITY_FILES];
1773         Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1774 #ifdef ENABLE_PKCS11
1775         Key **keys;
1776         int nkeys;
1777 #endif /* PKCS11 */
1778
1779         n_ids = 0;
1780         memset(identity_files, 0, sizeof(identity_files));
1781         memset(identity_keys, 0, sizeof(identity_keys));
1782
1783 #ifdef ENABLE_PKCS11
1784         if (options.pkcs11_provider != NULL &&
1785             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1786             (pkcs11_init(!options.batch_mode) == 0) &&
1787             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1788             &keys)) > 0) {
1789                 for (i = 0; i < nkeys; i++) {
1790                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1791                                 key_free(keys[i]);
1792                                 continue;
1793                         }
1794                         identity_keys[n_ids] = keys[i];
1795                         identity_files[n_ids] =
1796                             xstrdup(options.pkcs11_provider); /* XXX */
1797                         n_ids++;
1798                 }
1799                 free(keys);
1800         }
1801 #endif /* ENABLE_PKCS11 */
1802         if ((pw = getpwuid(original_real_uid)) == NULL)
1803                 fatal("load_public_identity_files: getpwuid failed");
1804         pwname = xstrdup(pw->pw_name);
1805         pwdir = xstrdup(pw->pw_dir);
1806         if (gethostname(thishost, sizeof(thishost)) == -1)
1807                 fatal("load_public_identity_files: gethostname: %s",
1808                     strerror(errno));
1809         for (i = 0; i < options.num_identity_files; i++) {
1810                 if (n_ids >= SSH_MAX_IDENTITY_FILES ||
1811                     strcasecmp(options.identity_files[i], "none") == 0) {
1812                         free(options.identity_files[i]);
1813                         continue;
1814                 }
1815                 cp = tilde_expand_filename(options.identity_files[i],
1816                     original_real_uid);
1817                 filename = percent_expand(cp, "d", pwdir,
1818                     "u", pwname, "l", thishost, "h", host,
1819                     "r", options.user, (char *)NULL);
1820                 free(cp);
1821                 public = key_load_public(filename, NULL);
1822                 debug("identity file %s type %d", filename,
1823                     public ? public->type : -1);
1824                 free(options.identity_files[i]);
1825                 identity_files[n_ids] = filename;
1826                 identity_keys[n_ids] = public;
1827
1828                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
1829                         continue;
1830
1831                 /* Try to add the certificate variant too */
1832                 xasprintf(&cp, "%s-cert", filename);
1833                 public = key_load_public(cp, NULL);
1834                 debug("identity file %s type %d", cp,
1835                     public ? public->type : -1);
1836                 if (public == NULL) {
1837                         free(cp);
1838                         continue;
1839                 }
1840                 if (!key_is_cert(public)) {
1841                         debug("%s: key %s type %s is not a certificate",
1842                             __func__, cp, key_type(public));
1843                         key_free(public);
1844                         free(cp);
1845                         continue;
1846                 }
1847                 identity_keys[n_ids] = public;
1848                 /* point to the original path, most likely the private key */
1849                 identity_files[n_ids] = xstrdup(filename);
1850                 n_ids++;
1851         }
1852         options.num_identity_files = n_ids;
1853         memcpy(options.identity_files, identity_files, sizeof(identity_files));
1854         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
1855
1856         explicit_bzero(pwname, strlen(pwname));
1857         free(pwname);
1858         explicit_bzero(pwdir, strlen(pwdir));
1859         free(pwdir);
1860 }
1861
1862 static void
1863 main_sigchld_handler(int sig)
1864 {
1865         int save_errno = errno;
1866         pid_t pid;
1867         int status;
1868
1869         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
1870             (pid < 0 && errno == EINTR))
1871                 ;
1872
1873         signal(sig, main_sigchld_handler);
1874         errno = save_errno;
1875 }